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Any Innodyn news?
- Thread starter cjensen
- Start date
gmcjetpilot
Well Known Member
The dream of a small jet or turboprop?
I don't think the panache or aura of turbine whine and smell of kerosene will ever fade, especially a cheap turbine? May be it is like owning a P-51, may be attainable but never practical or cheap. Innodyn or not I don't think small turbines are practical in general and in a RV airframe a particular an even poorer match. Where do you see single engine turboprops, Cessna Caravan, Pilatus PC-12, SOCATA TBM-700 and Piper Meridian. There are some notable conversions of Dehavilland Otters and Beavers. So it seems the aerospace industry has sized the practical use to cabin class singles and utilitarian haulers.
I looked all the successful turbo prop experimentals an some factory planes, well successful is a relative term. I flew a Swearingen Metroliner SA227, so I know a little about turboprops. The Lancair Turbine program (projet) I think uses a Walter de-rated / flat rated 750 shaft HP engine. Not sure what the engine cost is but I thing engine and prop will be the better part of $150,000.
As far as other prop jets there was a Luscombe (yes a high wing taildragger) that was for sale as part of bankruptcy on the NET just a few weeks ago. It uses a small Solor APU engine rated up to about 160 HP. Its fuel burn is 1.3 lb/shp-hr. If you do the math it is quite a fuel flow and still makes less than a Lycoming O360. Innodyne claims some crazy 0.7 lb/shp-he efficiency? I remember seeing this Solor Propjet Luscombe at a few airshows in the late 90's. It was not practical as a power plant in general and much less for that airframe in particular.
Besides the 750shp Walter, the only other turbo props in contention I can think of are the Pratt & Whitney of Canada PT6's and The Garrett TPE 331's. They all come in at 600+ HP and typically 700+ HP (up to 1000shp). If less HP is needed or allowed on take off they flat rate it, which means the fuel controller reduce fuel to lower sea level HP. Since the engine is de-rated it can maintain that sea level power to a higher altitude, and which point power falls off with altitude. This kind of power will OVER POWERS most experimental aircraft. Obviously the RV with a 220mph Vne (that is TRUE AIRSPEED BY THE WAY NOT INDICATED) is not going to handle that kind power.
My choice if I could dream of a personal turbine engine would be a Pratt & Whitney PT6, but the cost and size would not make it suitable for a RV or even a Lanciair. The Walter (made in Eastern Europe) is of a similar design to the PT6 but cost less, so that is probably the reason Lancair supports the Walter as their turbine candidate. Either way you are looking at 500+ de-rated shp at least. A RV-x can not use that much power (Vne).
The nice thing about a PT6 (and Walter) is its a free turbine where the turbine the drives the gear box, that drives the prop, is separate and not mechanically connected to the "Gas Section" of the turbine. It is connected by hot gas only and the power turbine is FREE to spin independent of the GAS turbine. This allows the turbine to "spool up" with out immediately turning the prop. Direct drive turbines where the prop is mechanically connected to the gas section are harder to start and need big batteries (banks of batteries), since you have to turn the prop while starting as well as the "gas section". The Metro IV (Garrett TPE331) is like this and why you always see JUMP Cart's on airplanes using these engines. The jump cart provides extra battery power. You can start on internal battery only but it is hard on the batteries and the engine starts much hotter. The "battery" jump cart allows the engine to turn faster during start. Failure to turn a turbine fast enough during start, before adding fuel, can cause a HOT START and destroy the engine.
As far as pure jets, Greg Richter of Blue Mountain Avionics converted a GE T58 turbine normally used for Helicopters by removing the accessory case and using it for it's jet thrust alone, about 800lbs thrust. The article of Greg's Jet powered Cozy is in the EAA Sport Aviation Magazine this month or last month. The bottom line it works and works well, but Greg's last statement is it is NOT practical. The RV is not suitable for jet thrust obviously but the advantage of just chucking all the gear box and prop control is pretty obvious. Although not practical as Greg said the performance is of his JetCozy is impressive. However economy is not the hallmark of jet travel, especially in a two seat plane with little cargo/baggage.
That leads me to the Innodyn. First they have not done themselves any favor with some of the semi-data they have out there, which seems to defy normal efficiency by a factor of 2. Also the history of the company and promises others can speak to make me wary of purchasing one.
My conclusion is there is no chance a suitable small turbo prop engine in the 180-250 HP range is really possible (practical). THERE is an economy of scale. If you are going to make a true aircraft capable turbine designed for the purpose of being a power plant for an airplane, it is going to come in at least in 400 hp and more, like the 600 hp range. They will also cost well over $100,000. Also the RV is not big enough or have a high enough Vne to take advantage of turbine power. If you want a jet the Lancair/Walter seems to be one of the the best things on the market.
Can a RV use a de-rated 700HP engine? I doubt it, a Pressurized airframe like the Lancair is a better match. RV's are just NOT jet aircraft. The Jet Powered Cozy Greg Richter, although not really practical is a better match, in my opinion, than any turbine in a RV.
Now can Innodyn really make a 180-220HP turbine that is cheap, practical and safe. Well from what I know they have made some simplifications is design and systems to make it work at the "SCALE" or size they are at. Every turboprop is usually saddled with a heavy complicated gear box, hydraulic prop, torque measuring device (usually strain gages) and fuel controllers. All this stuff is complicated and expensive. Is it worth it to have all these items only for 200 HP? Innodyn has simplified the prop (no hydraulic prop), gear box (no torque measurement) and the fuel controller are all no doubt simplified.
You can put a turbine on anything:
http://www.aardvark.co.nz/pjet/turbinenuts.shtml
But that does not mean you should. If you want a Turbine Jet aircraft plan on at least 1/4 million dollars, not $80 grand. The RV will never be a great match for a turbine and practical turbo prop powerplant/props are at least +600HP. At this time I don't see Innodyn being practical. More important is safety. Is it safe?
Here is my idea for a cheap turbo prop engine prop set up. I would buy an wrecked TurboProp Aero Commander with two good Garrett TPE331's with a partner. We would part the plane out and use the two engines for two single engine projects. The airframe could be any high speed aircraft (Lancair), Thunder Mustang or may be a big heavy hauler bush plane designed for a IO540 and super size the plane. (If you can't go fast go heavy to take advantage of the HP.) You would get all the engine instruments, controllers, prop (you hope not damaged) and bits and pieces to make them run. PT6's are better but just too popular and you will pay a fortune. The TPE331 have been around and have got to the point of high reliability. The Dash 10 models are very good. These engines or variations are in Cessna Conquest, Aero Commanders, BAe Jet stream and Fairchild/Swearingen Metro. The latter commuter planes have higher HP versions up to 1200SHP with AWI (A-we). AWI is alcohol water injection.
I would never discourage anyone's JET DREAMS, but I think there is better ways to go and would go with a REAL aircraft turboprop and not this experimental set up.
George
I don't think the panache or aura of turbine whine and smell of kerosene will ever fade, especially a cheap turbine? May be it is like owning a P-51, may be attainable but never practical or cheap. Innodyn or not I don't think small turbines are practical in general and in a RV airframe a particular an even poorer match. Where do you see single engine turboprops, Cessna Caravan, Pilatus PC-12, SOCATA TBM-700 and Piper Meridian. There are some notable conversions of Dehavilland Otters and Beavers. So it seems the aerospace industry has sized the practical use to cabin class singles and utilitarian haulers.
I looked all the successful turbo prop experimentals an some factory planes, well successful is a relative term. I flew a Swearingen Metroliner SA227, so I know a little about turboprops. The Lancair Turbine program (projet) I think uses a Walter de-rated / flat rated 750 shaft HP engine. Not sure what the engine cost is but I thing engine and prop will be the better part of $150,000.
As far as other prop jets there was a Luscombe (yes a high wing taildragger) that was for sale as part of bankruptcy on the NET just a few weeks ago. It uses a small Solor APU engine rated up to about 160 HP. Its fuel burn is 1.3 lb/shp-hr. If you do the math it is quite a fuel flow and still makes less than a Lycoming O360. Innodyne claims some crazy 0.7 lb/shp-he efficiency? I remember seeing this Solor Propjet Luscombe at a few airshows in the late 90's. It was not practical as a power plant in general and much less for that airframe in particular.
Besides the 750shp Walter, the only other turbo props in contention I can think of are the Pratt & Whitney of Canada PT6's and The Garrett TPE 331's. They all come in at 600+ HP and typically 700+ HP (up to 1000shp). If less HP is needed or allowed on take off they flat rate it, which means the fuel controller reduce fuel to lower sea level HP. Since the engine is de-rated it can maintain that sea level power to a higher altitude, and which point power falls off with altitude. This kind of power will OVER POWERS most experimental aircraft. Obviously the RV with a 220mph Vne (that is TRUE AIRSPEED BY THE WAY NOT INDICATED) is not going to handle that kind power.
My choice if I could dream of a personal turbine engine would be a Pratt & Whitney PT6, but the cost and size would not make it suitable for a RV or even a Lanciair. The Walter (made in Eastern Europe) is of a similar design to the PT6 but cost less, so that is probably the reason Lancair supports the Walter as their turbine candidate. Either way you are looking at 500+ de-rated shp at least. A RV-x can not use that much power (Vne).
The nice thing about a PT6 (and Walter) is its a free turbine where the turbine the drives the gear box, that drives the prop, is separate and not mechanically connected to the "Gas Section" of the turbine. It is connected by hot gas only and the power turbine is FREE to spin independent of the GAS turbine. This allows the turbine to "spool up" with out immediately turning the prop. Direct drive turbines where the prop is mechanically connected to the gas section are harder to start and need big batteries (banks of batteries), since you have to turn the prop while starting as well as the "gas section". The Metro IV (Garrett TPE331) is like this and why you always see JUMP Cart's on airplanes using these engines. The jump cart provides extra battery power. You can start on internal battery only but it is hard on the batteries and the engine starts much hotter. The "battery" jump cart allows the engine to turn faster during start. Failure to turn a turbine fast enough during start, before adding fuel, can cause a HOT START and destroy the engine.
As far as pure jets, Greg Richter of Blue Mountain Avionics converted a GE T58 turbine normally used for Helicopters by removing the accessory case and using it for it's jet thrust alone, about 800lbs thrust. The article of Greg's Jet powered Cozy is in the EAA Sport Aviation Magazine this month or last month. The bottom line it works and works well, but Greg's last statement is it is NOT practical. The RV is not suitable for jet thrust obviously but the advantage of just chucking all the gear box and prop control is pretty obvious. Although not practical as Greg said the performance is of his JetCozy is impressive. However economy is not the hallmark of jet travel, especially in a two seat plane with little cargo/baggage.
That leads me to the Innodyn. First they have not done themselves any favor with some of the semi-data they have out there, which seems to defy normal efficiency by a factor of 2. Also the history of the company and promises others can speak to make me wary of purchasing one.
My conclusion is there is no chance a suitable small turbo prop engine in the 180-250 HP range is really possible (practical). THERE is an economy of scale. If you are going to make a true aircraft capable turbine designed for the purpose of being a power plant for an airplane, it is going to come in at least in 400 hp and more, like the 600 hp range. They will also cost well over $100,000. Also the RV is not big enough or have a high enough Vne to take advantage of turbine power. If you want a jet the Lancair/Walter seems to be one of the the best things on the market.
Can a RV use a de-rated 700HP engine? I doubt it, a Pressurized airframe like the Lancair is a better match. RV's are just NOT jet aircraft. The Jet Powered Cozy Greg Richter, although not really practical is a better match, in my opinion, than any turbine in a RV.
Now can Innodyn really make a 180-220HP turbine that is cheap, practical and safe. Well from what I know they have made some simplifications is design and systems to make it work at the "SCALE" or size they are at. Every turboprop is usually saddled with a heavy complicated gear box, hydraulic prop, torque measuring device (usually strain gages) and fuel controllers. All this stuff is complicated and expensive. Is it worth it to have all these items only for 200 HP? Innodyn has simplified the prop (no hydraulic prop), gear box (no torque measurement) and the fuel controller are all no doubt simplified.
You can put a turbine on anything:
http://www.aardvark.co.nz/pjet/turbinenuts.shtml
But that does not mean you should. If you want a Turbine Jet aircraft plan on at least 1/4 million dollars, not $80 grand. The RV will never be a great match for a turbine and practical turbo prop powerplant/props are at least +600HP. At this time I don't see Innodyn being practical. More important is safety. Is it safe?
Here is my idea for a cheap turbo prop engine prop set up. I would buy an wrecked TurboProp Aero Commander with two good Garrett TPE331's with a partner. We would part the plane out and use the two engines for two single engine projects. The airframe could be any high speed aircraft (Lancair), Thunder Mustang or may be a big heavy hauler bush plane designed for a IO540 and super size the plane. (If you can't go fast go heavy to take advantage of the HP.) You would get all the engine instruments, controllers, prop (you hope not damaged) and bits and pieces to make them run. PT6's are better but just too popular and you will pay a fortune. The TPE331 have been around and have got to the point of high reliability. The Dash 10 models are very good. These engines or variations are in Cessna Conquest, Aero Commanders, BAe Jet stream and Fairchild/Swearingen Metro. The latter commuter planes have higher HP versions up to 1200SHP with AWI (A-we). AWI is alcohol water injection.
I would never discourage anyone's JET DREAMS, but I think there is better ways to go and would go with a REAL aircraft turboprop and not this experimental set up.
George
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Innodyne has been putting back delivery dates for some time so hard to trust what they say. I agree with George, the published FF numbers are highly unlikely with this design of turbine and pressure ratios involved.
I friend has been installing a 425hp Allison turbine in a Glassair now for almost 4 years with professional help. Still not done, lots of heachaches and lots of $$$. He said he would NEVER do it again.
Another friend has a shop building composite turbine aircraft up here. Doing the Glassair, 2 Lancairs and a Legend (was Walter now installing 1000 shp Garrett!). These people all have big $$$$ and they'll need even more to buy the fuel for them operating at low altitudes.
There are some 150-250 hp turbines available but need suitable gearboxes designed to be usable. If you really must do this try Shane at Innovative Wings http://www.innovativewings.com/ up here in Canada. They have a lot of experience with turbine homebuilts.
Turbines are very cool but cheap they aren't. You'll need some really big tanks to make it usuable on an RV and watch that ASI if you install something over 200hp.
I friend has been installing a 425hp Allison turbine in a Glassair now for almost 4 years with professional help. Still not done, lots of heachaches and lots of $$$. He said he would NEVER do it again.
Another friend has a shop building composite turbine aircraft up here. Doing the Glassair, 2 Lancairs and a Legend (was Walter now installing 1000 shp Garrett!). These people all have big $$$$ and they'll need even more to buy the fuel for them operating at low altitudes.
There are some 150-250 hp turbines available but need suitable gearboxes designed to be usable. If you really must do this try Shane at Innovative Wings http://www.innovativewings.com/ up here in Canada. They have a lot of experience with turbine homebuilts.
Turbines are very cool but cheap they aren't. You'll need some really big tanks to make it usuable on an RV and watch that ASI if you install something over 200hp.
gmcjetpilot
Well Known Member
I agree, but watch that TAS
One thing I would point out is Flutter speed or Vne is not IAS. Flutter or Vne is based on TAS. Since for every Knot/MPH IAS, TAS increases roughly 2% for every thousand feet, e.g., at 10,000 feet, 100 mph indicated is really 120 mph (10 x 2% = 20% difference). If sea level Vne is 220 indicated, Vne is ONLY a 169 mph IAS at FL180 (18,000 feet), or 220 mph TAS. With Turbine power you may be able to maintain sea level power well into high altitudes and easily exceed the Vne of the airframe.
For most RV'ers Vne in level flight at any altitude is not an issue since piston engine HP goes down with altitude, so we tend not to push Vne in level flight. However if you are descending fast from higher altitudes you can exceed Vne easily if you are not conscious of the relationship of Vne and IAS with altitude.
I think Doug posted the RVator article. Jets you don't use Vne or IAS above 20,000 / 25,000 feet. All limits are base on MACH number. Since MACH one (speed of sound) decreases with altitude your MACH limit or Vmo (Max Mach is like Vne but in MACH# not knots or MPH) remains constant. Unlike IAS, Vne in IAS is a function of altitude and always changing with altitude. So with a turbo prop you will not be able to take advantage of that excess high altitude power reserve and higher associated speed, unless the airframe has a high Vne/Vmo. This is one of the problems with the Beach Bonanza turboprop conversion, which does use the Allison which I forgot about as a popular small turbine that rv6ejguy mentioned. What do one of those factory fast single engine Turboprops from Piper, Pilatus or SOCATA cost?
I guess I am just going to keep my RV-7 and put some turbine sounds on my Ipod and pipe it thru the intercom. I guess I can put a little injector in the exhaust pipe and spray a little tiny amount of kerosene in for the smell?
G
Everything you said rv6ejguy, and that's want I wanted to say but you did it in 1/10th the words.rv6ejguy said:
One thing I would point out is Flutter speed or Vne is not IAS. Flutter or Vne is based on TAS. Since for every Knot/MPH IAS, TAS increases roughly 2% for every thousand feet, e.g., at 10,000 feet, 100 mph indicated is really 120 mph (10 x 2% = 20% difference). If sea level Vne is 220 indicated, Vne is ONLY a 169 mph IAS at FL180 (18,000 feet), or 220 mph TAS. With Turbine power you may be able to maintain sea level power well into high altitudes and easily exceed the Vne of the airframe.
For most RV'ers Vne in level flight at any altitude is not an issue since piston engine HP goes down with altitude, so we tend not to push Vne in level flight. However if you are descending fast from higher altitudes you can exceed Vne easily if you are not conscious of the relationship of Vne and IAS with altitude.
I think Doug posted the RVator article. Jets you don't use Vne or IAS above 20,000 / 25,000 feet. All limits are base on MACH number. Since MACH one (speed of sound) decreases with altitude your MACH limit or Vmo (Max Mach is like Vne but in MACH# not knots or MPH) remains constant. Unlike IAS, Vne in IAS is a function of altitude and always changing with altitude. So with a turbo prop you will not be able to take advantage of that excess high altitude power reserve and higher associated speed, unless the airframe has a high Vne/Vmo. This is one of the problems with the Beach Bonanza turboprop conversion, which does use the Allison which I forgot about as a popular small turbine that rv6ejguy mentioned. What do one of those factory fast single engine Turboprops from Piper, Pilatus or SOCATA cost?
I guess I am just going to keep my RV-7 and put some turbine sounds on my Ipod and pipe it thru the intercom. I guess I can put a little injector in the exhaust pipe and spray a little tiny amount of kerosene in for the smell?
G
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cjensen
Well Known Member
whoa...wait a minute here, i was just wondering if there was anything new in development from innodyn that wasn't yet published on the website.
i think this is an interesting idea, but who knows where it will really lead. i do know a little about a little about turbo props since i crew a king air for my fbo (no biggie, you didn't know that), so a lesson is not necessary here. however, i do appreciate the opinions on the little innodyn. i don't have anywhere near the amount of money that would be required to even think about a pt-6 or 331 (maybe even an innodyn), but i do believe that the small turbine has plenty of promise to be a viable option in the 180-200hp range someday. it may not be this company that pulls it off, but we have the resources to make this work someday.
you gotta believe!!
i think this is an interesting idea, but who knows where it will really lead. i do know a little about a little about turbo props since i crew a king air for my fbo (no biggie, you didn't know that), so a lesson is not necessary here. however, i do appreciate the opinions on the little innodyn. i don't have anywhere near the amount of money that would be required to even think about a pt-6 or 331 (maybe even an innodyn), but i do believe that the small turbine has plenty of promise to be a viable option in the 180-200hp range someday. it may not be this company that pulls it off, but we have the resources to make this work someday.
you gotta believe!!
gmcjetpilot
Well Known Member
Just Hanger flying, no biggie
).
I think the real future myself is in small jet turbines. Turbo Props are just too complicated. They do have their niche in business aviation and short haul freight. Turboprops are gone or fading from commuter aviation in most markets. I have done the commuter turboprop pilot thing, corporate Jet captain on Citation's (when there where just 2 basic models the 500/550 and 650, now there are several more models) and now fly larger jets. To me props are great and love piston engines (want a radial someday, may be a Stearman), but the new small jet engines made by Williams and P&W seem like the future. If I am burning Jet-A, I personally don't want a prop at all. Cost of Jet engines are coming down and efficiency going up. Of course it depends on what you want to do. Fly high and fast? Go-Jet. Fly low, haul stuff or STOL? Prop. However even the military C-17 jet transport is a STOL plane. Beating the air to death with a prop, whether powered by piston or turbine makes no difference to me, I just want to fly, while not having to sell a kidney. You can by one of those old military jet trainers for less than $100K, but I could not afford the gas bill.
The thing where Greg Richter took an old military Helicopter engine, removing the gear box and turning it into a pure turbojet seems interesting. He talked of fuel burn, range, speed in the article but did not say anything about the cost of engine and installation. It is all in fun CJ; just hanger talk; sorry I don't know anymore about Innodyn, but Innodyn's communication has always been their weak point and their progress does not seem to match their predictions. However they are willing to take your money. George
What King air do you fly? Cool. Yea it is a general discussion for anyone to read not only someone with your experience. We do differ in the thought or opinion that 180-200 hp is practical for a turboprop as I mentioned, but I could be wrong; I hope I am wrong, and if Innodyn does it, great. I have doubts with Innodyn but more power to them (pun intendedcjensen said:whoa...wait a minute here, i was just wondering if there was anything new in development from innodyn that wasn't yet published on the website.
i don't have anywhere near the amount of money that would be required to even think about a pt-6 or 331 (maybe even an innodyn), but i do believe that the small turbine has plenty of promise to be a viable option in the 180-200hp range someday. it may not be this company that pulls it off, but we have the resources to make this work someday. you gotta believe!!
). I think the real future myself is in small jet turbines. Turbo Props are just too complicated. They do have their niche in business aviation and short haul freight. Turboprops are gone or fading from commuter aviation in most markets. I have done the commuter turboprop pilot thing, corporate Jet captain on Citation's (when there where just 2 basic models the 500/550 and 650, now there are several more models) and now fly larger jets. To me props are great and love piston engines (want a radial someday, may be a Stearman), but the new small jet engines made by Williams and P&W seem like the future. If I am burning Jet-A, I personally don't want a prop at all. Cost of Jet engines are coming down and efficiency going up. Of course it depends on what you want to do. Fly high and fast? Go-Jet. Fly low, haul stuff or STOL? Prop. However even the military C-17 jet transport is a STOL plane. Beating the air to death with a prop, whether powered by piston or turbine makes no difference to me, I just want to fly, while not having to sell a kidney. You can by one of those old military jet trainers for less than $100K, but I could not afford the gas bill.
The thing where Greg Richter took an old military Helicopter engine, removing the gear box and turning it into a pure turbojet seems interesting. He talked of fuel burn, range, speed in the article but did not say anything about the cost of engine and installation. It is all in fun CJ; just hanger talk; sorry I don't know anymore about Innodyn, but Innodyn's communication has always been their weak point and their progress does not seem to match their predictions. However they are willing to take your money. George
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cjensen
Well Known Member
i know what you mean about the communication thing from innodyn. i have several emails in to them over the last few months, and only had one returned, and it contained little in response.
i did read that article on richter's cozy. that is a really neat conversion to a jet. 'course he's got the dough...
i'm just an optimistic person (not saying you aren't by any means! ), so i love to think of the promise of turbine (prop or jet) powered machines being within monetary reach someday. may never happen, but i can hope! the small jet engines from williams and p&w are great, but they'll still be too pricey for the experimental market and those wanting insurance (for most anyway).
i just started flying a king air 200 on charter, crew of two. early model, serial number 10! she's a beauty though! new p & i, really nice looking. we've one more trip this week, then she's down for an engine o/h.
btw, innodyn will get no money from me unless they are proven and already shipping, and then only if i can justify it to my boss (wife).
i did read that article on richter's cozy. that is a really neat conversion to a jet. 'course he's got the dough...
i'm just an optimistic person (not saying you aren't by any means!
), so i love to think of the promise of turbine (prop or jet) powered machines being within monetary reach someday. may never happen, but i can hope! the small jet engines from williams and p&w are great, but they'll still be too pricey for the experimental market and those wanting insurance (for most anyway).i just started flying a king air 200 on charter, crew of two. early model, serial number 10! she's a beauty though! new p & i, really nice looking. we've one more trip this week, then she's down for an engine o/h.
btw, innodyn will get no money from me unless they are proven and already shipping, and then only if i can justify it to my boss (wife).
gmcjetpilot
Well Known Member
Turbines for GA?
The promise of reliability of turbine engines is very attractive even for GA. The issue is when a guy flys 100 hours a year its a little spendy having a turbine "asset" just sitting around. I fly large jets internationally. It amazes me how long and we run these planes; We might do a 12-14 hour flight and layover while the plane goes on (around the world) with another crew, taking it right away for another leg. After that crew gets off their +8 hour flight, another crew brings the same plane back for my next leg. Some times the plane is in the air +18 hours a day for several days, 1/2 way round the world and back. This is all done with only short daily "checks" or ETOPS checks (over water flights). This is where the expense of turbine power is justified. The average GA guy in a personal plane is not really going to take advantage of this kind of reliability. Since engine "failure", true honest to goodness crank shaft, rod poking out the side of the case failures, are rare. A GA guy with a turbine may not be any-less likely NOT to run out of fuel or fly in weather over their head. So the promise of (safety/reliability) of turbines is not really justified by the realities of much higher costs, which I don't think will ever be low. The metals and manufacturing are expensive. As I first said the aura and panache of the whining call of turbines is a strong one, but I think a radial or Merlin sounds better. Georgerv72004 said:
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Some interesting comments made.
Why are turboprops desirable? A few things come to mind- excellent reliability, High HP/low weight, and smooth operation.
The downsides: extremely high cost, high fuel burn rate, complexity issues (maintenance, installation, licensing...) , not sized well for our GA application. Possible problems with heat generation and noise.
As a comparison, it seems to me that the Mazda wankel/rotary design has all the advantages of the turbine with none of the problems. The Lycs do almost as well, except for smooth running and a few reliability issues.
Why are turboprops desirable? A few things come to mind- excellent reliability, High HP/low weight, and smooth operation.
The downsides: extremely high cost, high fuel burn rate, complexity issues (maintenance, installation, licensing...) , not sized well for our GA application. Possible problems with heat generation and noise.
As a comparison, it seems to me that the Mazda wankel/rotary design has all the advantages of the turbine with none of the problems. The Lycs do almost as well, except for smooth running and a few reliability issues.
gmcjetpilot
Well Known Member
Wankel is not a Turbine
EAA Sport Aviation, November 2005, "Speed Jacket"... what happens when you really change engines in a Cozy?, by Amy Laboda.
(Greg Richter, founder of Blue Mountain Avionics, discusses the engines changes he made before installing his latest power plant, a GE turbine.)
"I'd flown the Cozy with a O-235....I tried the O320.... (than) I thought I could get a Mazda...."
In the end, Richter says, his Mazda engine just wasn't practical.
"For every hour I flew, I'd have to spend an hour on the ground wrenching on it. One day I realized it's sat on the ground for nearly a year. I wasn't flying it because the engine was just too much work."
Turbines are maintenance free, a Wankel is not. Look Calling a Wankel a turbine is like calling an apple a banana. They both are in the produce section but an Apple will never be a Banana.
Any honest alternative engine advocate will readily admit that they spend lots of time on there engine, both in installation, operation and endless modification, but they will also tell you that this is the attraction of these engines, a tinker's play land. If you want to fly get a Lycoming. You want to experiment and tinker get an alternative.
With all do respect Cobra the physics and everything about a rotary engine has NOTHING to do with a turbine. If you want to think that this is a valid analogy, OK, but respectfully disagree as it is inaccurate from any standpoint you can think of. Imagine a Mazda engine scaled up to produce 50,000 lbs of thrust of a large jet engine. What would that look like? Apples and Apples.
Turbines are continuous cycle machines. A Wankel in the end is still a Suck-Squeeze-Bang-Blow engine. If you think the "rotor" in the Mazda is like an axial or centrifugal turbine I could not even start to tell you how inaccurate that analogy is. Yes the Mazda rotor "goes around", but it does not go around concentrically, it is eccentric and thus actually "translates" as well as rotates, very un-turbine like.
http://www.keveney.com/Wankel.html
Rotary with its long thin combustion chamber will always suffer efficiency issues, however I have the highest respect for late Dr. Wankel.
Merry Christmas "Big Cobra"
George
(Any one see the 2003 movie "The In-Laws", with Michael Douglas and Albert Brooks, where Douglas is a spy and involves his future in-law (played by Albert Brooks) in a spy scheme. As a cover Douglas tells a covert underworld contact that Albert is the "Big Cobra", a famous but never seen figure in the underworld as a cover. The underworld boss is "attracted" to The "Big Cobra" (the unwitting in-law), hilarious. You will have to see the move to find out where the Big Cobra gets his name from. There is few brief but good flying scenes. Sorry but sometimes I hear Cobra and think of this movie, but it is worth seeing on DVD.)
Ohoooo Boy, here we go.cobra said:
EAA Sport Aviation, November 2005, "Speed Jacket"... what happens when you really change engines in a Cozy?, by Amy Laboda.
(Greg Richter, founder of Blue Mountain Avionics, discusses the engines changes he made before installing his latest power plant, a GE turbine.)
"I'd flown the Cozy with a O-235....I tried the O320.... (than) I thought I could get a Mazda...."
In the end, Richter says, his Mazda engine just wasn't practical.
"For every hour I flew, I'd have to spend an hour on the ground wrenching on it. One day I realized it's sat on the ground for nearly a year. I wasn't flying it because the engine was just too much work."
Turbines are maintenance free, a Wankel is not. Look Calling a Wankel a turbine is like calling an apple a banana. They both are in the produce section but an Apple will never be a Banana.
Any honest alternative engine advocate will readily admit that they spend lots of time on there engine, both in installation, operation and endless modification, but they will also tell you that this is the attraction of these engines, a tinker's play land. If you want to fly get a Lycoming. You want to experiment and tinker get an alternative.
With all do respect Cobra the physics and everything about a rotary engine has NOTHING to do with a turbine. If you want to think that this is a valid analogy, OK, but respectfully disagree as it is inaccurate from any standpoint you can think of. Imagine a Mazda engine scaled up to produce 50,000 lbs of thrust of a large jet engine. What would that look like? Apples and Apples.
Turbines are continuous cycle machines. A Wankel in the end is still a Suck-Squeeze-Bang-Blow engine. If you think the "rotor" in the Mazda is like an axial or centrifugal turbine I could not even start to tell you how inaccurate that analogy is. Yes the Mazda rotor "goes around", but it does not go around concentrically, it is eccentric and thus actually "translates" as well as rotates, very un-turbine like.
http://www.keveney.com/Wankel.html
Rotary with its long thin combustion chamber will always suffer efficiency issues, however I have the highest respect for late Dr. Wankel.
Merry Christmas "Big Cobra"
George
(Any one see the 2003 movie "The In-Laws", with Michael Douglas and Albert Brooks, where Douglas is a spy and involves his future in-law (played by Albert Brooks) in a spy scheme. As a cover Douglas tells a covert underworld contact that Albert is the "Big Cobra", a famous but never seen figure in the underworld as a cover. The underworld boss is "attracted" to The "Big Cobra" (the unwitting in-law), hilarious. You will have to see the move to find out where the Big Cobra gets his name from. There is few brief but good flying scenes. Sorry but sometimes I hear Cobra and think of this movie, but it is worth seeing on DVD.)
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Jconard
Well Known Member
Quote: "As a comparison, it seems to me that the Mazda wankel/rotary design has all the advantages of the turbine with none of the problems. The Lycs do almost as well, except for smooth running and a few reliability issues."
.....bubbling noise ( sounds like a gas being drawn through water)....sudden inhaling noise.....cough, cough, wheeze, goofy laughter.
Please, Please, Please put down the pipe. Remember kids, even marijuana is a drug, and even occaisional use can seriously impair judgement and abstract reasoning. Long term use can lead to meglomania and cognitive decay.
.....bubbling noise ( sounds like a gas being drawn through water)....sudden inhaling noise.....cough, cough, wheeze, goofy laughter.
Please, Please, Please put down the pipe. Remember kids, even marijuana is a drug, and even occaisional use can seriously impair judgement and abstract reasoning. Long term use can lead to meglomania and cognitive decay.
rvatornate
Active Member
Tinkering on engines
Gmcjetpilot writes:
"Any honest alternative engine advocate will readily admit that they spend lots of time on there engine, both in installation, operation and endless modification, but they will also tell you that this is the attraction of these engines, a tinker's play land."
It always amazes me when someone who doesn't currently own one of these engines makes broad statements concerning the maintainence and workload of said engines. In the 400 plus hours I have flown behind my Egg/Sube, my work has consisted of oil changes every 25-40 hours, One set of new spark plugs, replacing the timing belt at the most recent annual, and reattaching a loose starter cable that I had improperly installed. All this from a package that took me 2.5 hours to take from crate to firewall, and a couple more hours the next day to have it run for the first time.
Yes, Jan has made a number of improvements during the 2+ years I have had my engine, and if I'd like to, I could upgrade. But I have never found myself in tinker's play land and easily fly many more hours than I do work on the engine.
Nathan Larson
N217JT RV9E
408 hours of flying....many less tinkering
Gmcjetpilot writes:
"Any honest alternative engine advocate will readily admit that they spend lots of time on there engine, both in installation, operation and endless modification, but they will also tell you that this is the attraction of these engines, a tinker's play land."
It always amazes me when someone who doesn't currently own one of these engines makes broad statements concerning the maintainence and workload of said engines. In the 400 plus hours I have flown behind my Egg/Sube, my work has consisted of oil changes every 25-40 hours, One set of new spark plugs, replacing the timing belt at the most recent annual, and reattaching a loose starter cable that I had improperly installed. All this from a package that took me 2.5 hours to take from crate to firewall, and a couple more hours the next day to have it run for the first time.
Yes, Jan has made a number of improvements during the 2+ years I have had my engine, and if I'd like to, I could upgrade. But I have never found myself in tinker's play land and easily fly many more hours than I do work on the engine.
Nathan Larson
N217JT RV9E
408 hours of flying....many less tinkering
gmcjetpilot
Well Known Member
Stick to the facts
Second this is NOT just a wild guess on my part or the first time you have heard this no doubt. I am glad your experience is positive, but most folks attracted to the alternative engines enjoy working and tinkering, may be needlessly but for fun. I am not putting down any engine, just expressing my opinion. In the context of the discussion of Turbine reliability or smoothness, only a Turbine can achieve that level of reliability.
I grant you I have never owned an "alternative engine", but from my first hand experience, thru several friends and several airport acquittance's, who have or are doing conversions, both Subaru, Mazda and V6's, I have formed my opinion. I have read every article and builder web site I could get a hold of on "alternative engines" over the last 20 years in coming to my conclusion. The latest article in Sport Aviation and Greg Richter's quote confirms everything I have known to be correct. If you disagree, OK. May be the Egg Subaru is the least tinker intensive of the alternatives. That is cool, but my opinion is most alternative engine installations do take more work to keep airborne.
My Lycoming gets unbuttoned for oil change every 25-35 hours, so you got me beat. However I have 1000's of hours with the Lycoming. I guess I could go synthetic oil and extend the oil change interval. However I am a bit of a tinker my self, so I do know the joy of tinkering.
No matter how mad you get at me it still does not change the facts. The Subaru which you propose is more complex: Belt drive cam's, gear reduction drive, electric props, radiators and extra dependency on electricity (electronic fuel injection and ignition). More systems, more parts equals more (potential) maintenance. At least the Mazda reduces parts count.
Look stop being amazed and have a Merry Christmas and Happy Holidays.
George
First of all you don't know me or my background. I am sorry if I offended you. That was not my intent.rvatornate said:
Second this is NOT just a wild guess on my part or the first time you have heard this no doubt. I am glad your experience is positive, but most folks attracted to the alternative engines enjoy working and tinkering, may be needlessly but for fun. I am not putting down any engine, just expressing my opinion. In the context of the discussion of Turbine reliability or smoothness, only a Turbine can achieve that level of reliability.
I grant you I have never owned an "alternative engine", but from my first hand experience, thru several friends and several airport acquittance's, who have or are doing conversions, both Subaru, Mazda and V6's, I have formed my opinion. I have read every article and builder web site I could get a hold of on "alternative engines" over the last 20 years in coming to my conclusion. The latest article in Sport Aviation and Greg Richter's quote confirms everything I have known to be correct. If you disagree, OK. May be the Egg Subaru is the least tinker intensive of the alternatives. That is cool, but my opinion is most alternative engine installations do take more work to keep airborne.
My Lycoming gets unbuttoned for oil change every 25-35 hours, so you got me beat. However I have 1000's of hours with the Lycoming. I guess I could go synthetic oil and extend the oil change interval. However I am a bit of a tinker my self, so I do know the joy of tinkering.
No matter how mad you get at me it still does not change the facts. The Subaru which you propose is more complex: Belt drive cam's, gear reduction drive, electric props, radiators and extra dependency on electricity (electronic fuel injection and ignition). More systems, more parts equals more (potential) maintenance. At least the Mazda reduces parts count.
Look stop being amazed and have a Merry Christmas and Happy Holidays.
George
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fodrv7
Well Known Member
Misread!
I have re-read this statement by Cobra five times:
As a comparison, it seems to me that the Mazda wankel/rotary design has all the advantages of the turbine with none of the problems.
I can't see where he says anything about it's design type or that it is a turbine or that it is a contiuous combustion engine; His ONLY comment is about it's advantages v. problems.
Really George, no wonder he jumped back. All he asked for was info on Innodyn progress and he got a theory lecture, including VNE is TAS.
Now my Beechcraft Bonanza manual here quotes VNE in both CAS & IAS. Can't see TAS anywhere.
TRIM-UP-WATER-OFF-METO-SET.
I have re-read this statement by Cobra five times:
As a comparison, it seems to me that the Mazda wankel/rotary design has all the advantages of the turbine with none of the problems.
I can't see where he says anything about it's design type or that it is a turbine or that it is a contiuous combustion engine; His ONLY comment is about it's advantages v. problems.
Really George, no wonder he jumped back. All he asked for was info on Innodyn progress and he got a theory lecture, including VNE is TAS.
Now my Beechcraft Bonanza manual here quotes VNE in both CAS & IAS. Can't see TAS anywhere.
TRIM-UP-WATER-OFF-METO-SET.
gmcjetpilot
Well Known Member
What the Whisky Tango Foxtrot
If you don't like my insight or technical analysis and comments I guess its too bad. What can I do I am not going to apologize to you. Several people told me they liked my input. I guess you are not one of them. I will survive.
Also I find you comments hypocritical. Cobra made this Innodyn thread into an "auto engine issue", not intended by the original post. WHERE where you to point out Cobra's error in changing the topic of the thread? I don't really care who high jacks a thread. Who are you the Thread Police?
When rvatornate made his comments, about how maintenance free his Egg Subaru is, where were you to point out that I never said ALL alternative engines are maintenance intensive?
Let me say it again a rotary engines do NOT have any of the characteristics of a turbine, EVER. I read what Cobra wrote. Reliability-no, power to weight-no, smoothness-no, Axial rotor-no. Advantages? What ones are those? high fuel consumption, high noise. Yes a rotary is cheaper than a turbine but so is a Briggs & Stratton. Cobra is entitled to his opinion. That is cool, and it is cool I disagree with his analogy; a Wankel is not a Turbine. There I said it agian.
Last "rvatornate" made his point about his experience with the Egg Subaru, which does not require him to tinker, but I never mentioned anything about Egg Subaru. However again let me say it, alternative engine installations take more tinkering in general. If you don't like that or agree that's OK with me, but please back your comments with facts and stop picking on me. At least "rvatornate" had anecdotal comments that where relevant to his point. Greg Richter says his Mazda power plant was TOO MUCH work to maintain. Kill the messenger. That is what he said not me. Ignore his comment, Ignore me please.
I am sorry your Beachcraft only mentions Vne in IAS, that is fine. If you don't believe me read the RVator article that was posted here on Vansairforce.net.
Here is the article posted and written Richard Vangrunsven, may you will believe him:http://www.vansaircraft.com/pdf/hp_limts.pdf
It is OK to disagree but for heck sakes have something to back it up with. It is true TAS is a function of Vne or flutter. Many low performance aircraft only give one Vne in IAS/CAS (for sea level). For airplanes that fly low TAS and Vne is not an issue. That is fine and no doubt the Vne has a "margin of safety" or buffer. However if you fly higher performance aircraft or sailplanes they have a Vne (IAS) vs altitude card. The higher you go the lower Vne is (IAS). The Boeing Jets I fly have an indicated airspeed indicator where Vne/Vmo is a needle ( or vertical speed tape on the PFD) that moves DOWN with altitude. I don't know what else to tell you, I guess Boeing, Van and my university professors at the school of engineering I graduated from are all wrong, and we all need to go to your Bonanza manual.
In your effort to criticize me and my post or make some unrelated comments out of context, really has shown where you are coming from. If you have something intelligent to say, than say it. Vne and jet engines are VERY relevant. If I offend you, I can't see what I said to do that, except I have an opinion and facts. May be it clashes with your perception. I am entitled to my opinion and back it up with facts or at least experience. My comments are well thought out and not intended just for you. When people do disagree and bring something to the table I learn, but your comments are a waste of time. If they are too technical just ignore them. Many people read these, who may have no experience with turbine engines or alternative engines, find the detailed info useful. You already have your mind made up.
Look what is your point? You don't like my post? OK. I get it. I am not thrilled with your's either.
Merry Christmas and Happy New Years George
Well first the original poster asked the question about Innodyn. I opened it up to:fodrv7 said:
Is the RV even the right airframe for a turbine?
Will economy of scale ever allow small turbines to be economically feasible?
Will economy of scale ever allow small turbines to be economically feasible?
If you don't like my insight or technical analysis and comments I guess its too bad. What can I do I am not going to apologize to you. Several people told me they liked my input. I guess you are not one of them. I will survive.
Also I find you comments hypocritical. Cobra made this Innodyn thread into an "auto engine issue", not intended by the original post. WHERE where you to point out Cobra's error in changing the topic of the thread? I don't really care who high jacks a thread. Who are you the Thread Police?
When rvatornate made his comments, about how maintenance free his Egg Subaru is, where were you to point out that I never said ALL alternative engines are maintenance intensive?
Let me say it again a rotary engines do NOT have any of the characteristics of a turbine, EVER. I read what Cobra wrote. Reliability-no, power to weight-no, smoothness-no, Axial rotor-no. Advantages? What ones are those? high fuel consumption, high noise. Yes a rotary is cheaper than a turbine but so is a Briggs & Stratton. Cobra is entitled to his opinion. That is cool, and it is cool I disagree with his analogy; a Wankel is not a Turbine. There I said it agian.
Last "rvatornate" made his point about his experience with the Egg Subaru, which does not require him to tinker, but I never mentioned anything about Egg Subaru. However again let me say it, alternative engine installations take more tinkering in general. If you don't like that or agree that's OK with me, but please back your comments with facts and stop picking on me. At least "rvatornate" had anecdotal comments that where relevant to his point. Greg Richter says his Mazda power plant was TOO MUCH work to maintain. Kill the messenger. That is what he said not me. Ignore his comment, Ignore me please.
I am sorry your Beachcraft only mentions Vne in IAS, that is fine. If you don't believe me read the RVator article that was posted here on Vansairforce.net.
Here is the article posted and written Richard Vangrunsven, may you will believe him:http://www.vansaircraft.com/pdf/hp_limts.pdf
It is OK to disagree but for heck sakes have something to back it up with. It is true TAS is a function of Vne or flutter. Many low performance aircraft only give one Vne in IAS/CAS (for sea level). For airplanes that fly low TAS and Vne is not an issue. That is fine and no doubt the Vne has a "margin of safety" or buffer. However if you fly higher performance aircraft or sailplanes they have a Vne (IAS) vs altitude card. The higher you go the lower Vne is (IAS). The Boeing Jets I fly have an indicated airspeed indicator where Vne/Vmo is a needle ( or vertical speed tape on the PFD) that moves DOWN with altitude. I don't know what else to tell you, I guess Boeing, Van and my university professors at the school of engineering I graduated from are all wrong, and we all need to go to your Bonanza manual.
In your effort to criticize me and my post or make some unrelated comments out of context, really has shown where you are coming from. If you have something intelligent to say, than say it. Vne and jet engines are VERY relevant. If I offend you, I can't see what I said to do that, except I have an opinion and facts. May be it clashes with your perception. I am entitled to my opinion and back it up with facts or at least experience. My comments are well thought out and not intended just for you. When people do disagree and bring something to the table I learn, but your comments are a waste of time. If they are too technical just ignore them. Many people read these, who may have no experience with turbine engines or alternative engines, find the detailed info useful. You already have your mind made up.
Look what is your point? You don't like my post? OK. I get it. I am not thrilled with your's either.
Merry Christmas and Happy New Years George
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fodrv7
Well Known Member
Take Five!
George,
Quite the opposite, I like your posts.
I search for them because they make me think and I end up getting out Kermode AC. Mechanics of Flight, and D. P. Davies Handling the Big Jets and searching the Net to refresh my memory of the topics you are discussing.
You really had me thinking on the Prop forum last month.
But if we are going to have an opinion on the forum then we must expect it to be challenged.
I wrote an early reply to the Innodyn post regarding your assertion that VNE was TAS, but ended up not posting it as I suspected you would get all wound up.
Surely we are trying to learn something here and if we intend to pass on ?wisdom? we need to be careful not to miss inform our fellow aviators, who might not have been around as long as you and I. So we ought to be sure our data is right??? and expect to be challenged from time to time.
I really love your bit regarding your posts, ?If they are too technical, just ignore them?.
OK Lets Get technical. I will try and avoid giving MY opinion but rather offer that of people better informed than me. And there is plenty of them.
So I rang a real old timer mate, Pat Larcey, Aeronautical Engineer and the bloke who was the Flight Test Engineer on the Handley Page Victor (what an amazing aircraft) and asked him for a refresher on VNE.
Here is what he said.
VNE is a Fixed IAS.
It is determined by a number of possible limitations; usually;
Engine overspeed
Buffet
Vibration
VNE is acceptable in most Light Aircraft until above 10,000?, due, as you point out, by encroaching on the onset of flutter at altitudes above 10,000?. But not necessarily determined by flutter.
He directed me o the CAR airworthiness regs (Australian) which state.
SUBPART G OPERATING LIMITATIONS AND INFORMATION
A26.1505 AIR-SPEED LIMITATIONS
(a) All flight speeds must be stated in terms of indicated air speed readings (IAS) in knots.
(b) The never exceed speed VNE must not exceed 0.9 VD .
NOTE: See also A26.629 (b).
(c) If VNE or VNO vary with altitude, there must be means to indicate to the pilot the appropriate limitations throughout the operating altitude range.
After a bit of Surfing I found that FAA Part 23.1545 Airspeed indicator. also makes it clear that VNE is a fixed IAS.
Regarding Ken Kreugers article, I re-read it as soon as I saw your post last week. Nowhere in the article does he say VNE is variable. Quite the opposite. The whole point of his article is that the RV VNEs work if you use the recommended power, as even if you cruise at high altitudes there isn?t enough power to cruise at speeds where flutter is an issue. He even states the flutter margin! But, and this is why he wrote the article, if you start over powering an RV the higher cruise speeds possible in your Super RV flutter might cause you some embarrassment. The table for the PIPISTREL SINUS isn?t his and is someone?s personal way to ensure he doesn?t risk flutter by ?Artificially? reducing the VNE. Which we all now know, if we accept the FAA and CASA definition is a fixed IAS.
I do fly high performance sailplanes, by the way, and specifically joined a particular club because they have wave over the field enabling flights to FL270. My last aircraft was the B777 (they took it away as they said I was too old to fly it anymore.) but despite what they said I do still remember that the VMO was a fixed 330KT IAS until limited by MMO. I seem to recall that the B747-400 did have two different VMOs I think depending on AUW. However, everything else I flew DC-9, A320/A330/A340 and B737 200 and 300 all had fixed IAS VMOs. And yes I do remember the Barber pole coming down and obscuring the ASI on the DC-9, but it?s all a bit vague as I spent the last 25 years flying ?Glass?.
George, I do apologise for offending you in taking you to task on VNE. My intent is not to offend but rather ensure that information on this forum is accurate and provides information that will assist in the safe operation of our fellow Rvs flyers.
If I didn?t live 8000nm away I would come over with a couple of beers for a Christmas drink.
Have a great Christmas and a great New Years Eve too .
Pete.
George,
Quite the opposite, I like your posts.
I search for them because they make me think and I end up getting out Kermode AC. Mechanics of Flight, and D. P. Davies Handling the Big Jets and searching the Net to refresh my memory of the topics you are discussing.
You really had me thinking on the Prop forum last month.
But if we are going to have an opinion on the forum then we must expect it to be challenged.
I wrote an early reply to the Innodyn post regarding your assertion that VNE was TAS, but ended up not posting it as I suspected you would get all wound up.
Surely we are trying to learn something here and if we intend to pass on ?wisdom? we need to be careful not to miss inform our fellow aviators, who might not have been around as long as you and I. So we ought to be sure our data is right??? and expect to be challenged from time to time.
I really love your bit regarding your posts, ?If they are too technical, just ignore them?.
OK Lets Get technical. I will try and avoid giving MY opinion but rather offer that of people better informed than me. And there is plenty of them.
So I rang a real old timer mate, Pat Larcey, Aeronautical Engineer and the bloke who was the Flight Test Engineer on the Handley Page Victor (what an amazing aircraft) and asked him for a refresher on VNE.
Here is what he said.
VNE is a Fixed IAS.
It is determined by a number of possible limitations; usually;
Engine overspeed
Buffet
Vibration
VNE is acceptable in most Light Aircraft until above 10,000?, due, as you point out, by encroaching on the onset of flutter at altitudes above 10,000?. But not necessarily determined by flutter.
He directed me o the CAR airworthiness regs (Australian) which state.
SUBPART G OPERATING LIMITATIONS AND INFORMATION
A26.1505 AIR-SPEED LIMITATIONS
(a) All flight speeds must be stated in terms of indicated air speed readings (IAS) in knots.
(b) The never exceed speed VNE must not exceed 0.9 VD .
NOTE: See also A26.629 (b).
(c) If VNE or VNO vary with altitude, there must be means to indicate to the pilot the appropriate limitations throughout the operating altitude range.
After a bit of Surfing I found that FAA Part 23.1545 Airspeed indicator. also makes it clear that VNE is a fixed IAS.
Regarding Ken Kreugers article, I re-read it as soon as I saw your post last week. Nowhere in the article does he say VNE is variable. Quite the opposite. The whole point of his article is that the RV VNEs work if you use the recommended power, as even if you cruise at high altitudes there isn?t enough power to cruise at speeds where flutter is an issue. He even states the flutter margin! But, and this is why he wrote the article, if you start over powering an RV the higher cruise speeds possible in your Super RV flutter might cause you some embarrassment. The table for the PIPISTREL SINUS isn?t his and is someone?s personal way to ensure he doesn?t risk flutter by ?Artificially? reducing the VNE. Which we all now know, if we accept the FAA and CASA definition is a fixed IAS.
I do fly high performance sailplanes, by the way, and specifically joined a particular club because they have wave over the field enabling flights to FL270. My last aircraft was the B777 (they took it away as they said I was too old to fly it anymore.) but despite what they said I do still remember that the VMO was a fixed 330KT IAS until limited by MMO. I seem to recall that the B747-400 did have two different VMOs I think depending on AUW. However, everything else I flew DC-9, A320/A330/A340 and B737 200 and 300 all had fixed IAS VMOs. And yes I do remember the Barber pole coming down and obscuring the ASI on the DC-9, but it?s all a bit vague as I spent the last 25 years flying ?Glass?.
George, I do apologise for offending you in taking you to task on VNE. My intent is not to offend but rather ensure that information on this forum is accurate and provides information that will assist in the safe operation of our fellow Rvs flyers.
If I didn?t live 8000nm away I would come over with a couple of beers for a Christmas drink.
Have a great Christmas and a great New Years Eve too .
Pete.
Barry
Well Known Member
Wow this is getting too technical. Poor Chad who had the misfortune to start this thread was only inquiring whether or not Innodyne were shipping their proposed turbine engine.
I am just a "little" pilot and am now baffled by all this technical information. What is a VMO and an MMO? I don't know if my RV6A has them and if so what do I do with them. Also I always thought that VD was some sort of disease it was best to avoid catching.
Poor old GMCPILOT seems to have got a real handbagging on all this. I hope it will not spoil his Christmas.
Barry
RV6A B&C Alternator, B&C Voltage Regulator, B&C Starter.
PS I try and avoid flying on the dark, windy and rainy nights!!
I am just a "little" pilot and am now baffled by all this technical information. What is a VMO and an MMO? I don't know if my RV6A has them and if so what do I do with them. Also I always thought that VD was some sort of disease it was best to avoid catching.
Poor old GMCPILOT seems to have got a real handbagging on all this. I hope it will not spoil his Christmas.
Barry
RV6A B&C Alternator, B&C Voltage Regulator, B&C Starter.
PS I try and avoid flying on the dark, windy and rainy nights!!
N395V
Well Known Member
I am not a techno geek and do not play one on TV but...........
The attraction of a small turbine and it's attendent whine and smell is really strong. I have been watching the innodyn turbine for many years. It is a rebirth of another company tht went under. Contrary to rumor they did make good on the deposits from their customers.
Spent a lot of time talking to one of their techs and Greg Richter (Blue Mountain) who was one of their original investors/customers.
Two things I gleaned from them. In order to get their fuel flows down to reasonable levels ($) they are pulsing the fuel. Given the small size and tolerances the added heat from low fuel flow is giving them expansion problems with resultant contact of the turbine to the case (not good).
Also to generate the HP and Torque the turbine needs to spin at 60,000 RPM
and is geared down to 2700-3000RPM at the outpuut shaft. The noise level of a 2700 RPM prop in cruise has to be horrendous not to mention the bearing and gear stresses of 60'000 to 3000 RPM.
I think it will be many years before they are ready for daily use from the standpoint of TBO, economy, and noise.
The attraction of a small turbine and it's attendent whine and smell is really strong. I have been watching the innodyn turbine for many years. It is a rebirth of another company tht went under. Contrary to rumor they did make good on the deposits from their customers.
Spent a lot of time talking to one of their techs and Greg Richter (Blue Mountain) who was one of their original investors/customers.
Two things I gleaned from them. In order to get their fuel flows down to reasonable levels ($) they are pulsing the fuel. Given the small size and tolerances the added heat from low fuel flow is giving them expansion problems with resultant contact of the turbine to the case (not good).
Also to generate the HP and Torque the turbine needs to spin at 60,000 RPM
and is geared down to 2700-3000RPM at the outpuut shaft. The noise level of a 2700 RPM prop in cruise has to be horrendous not to mention the bearing and gear stresses of 60'000 to 3000 RPM.
I think it will be many years before they are ready for daily use from the standpoint of TBO, economy, and noise.
cjensen
Well Known Member
N395V said:
didn't know that...good info...
N395V said:
yeah, 2700 rpm in cruise is unfriendly to everyone. we turn the props on the king air at 1850-1900 rpm in cruise...that's comfortable!
N395V said:
no worries on the hijacked thread...it happens.
back on topic anyone??
On topic. Innodyne never responded to the two E-mails I sent last year and the previous year. People who never respond to my querries never will get my money.
Off topic
George you might want to join the Eggenfellner Yahoo group. You will see dozens or hundreds of satisfied people flying his conversions with hundereds of hours on them with little or no maintenance performed during that time. While you might agrue that the Sube is more complicated, it has also proven to be as or more reliable than a Lycoming.
I agree that many one off auto conversions are a tinkerers dream but this has not been the case with Eggenfellners conversions.
Off topic
George you might want to join the Eggenfellner Yahoo group. You will see dozens or hundreds of satisfied people flying his conversions with hundereds of hours on them with little or no maintenance performed during that time. While you might agrue that the Sube is more complicated, it has also proven to be as or more reliable than a Lycoming.
I agree that many one off auto conversions are a tinkerers dream but this has not been the case with Eggenfellners conversions.
gmcjetpilot
Well Known Member
Thanks for the info
PS I think this discussion is great and is weeding out some misconceptions, including a few of my own. That is what a debate/discourses is all about.
No apologies necessary, especially if you have facts and data to back them up. I appreciate your references and examples. I always enjoy learning. Going off memory gets you in trouble sometimes. I have not digested your whole post yet. As far as I know (knew) flutter is a function of true air speed not indicated. Therefore if using IAS as your limit or Never Exceed, you have to make adjustment for high altitude flight. Also knowing some Hi-perf gliders have a Vne correction cards I made some assumptions as to why, may be incorrectly. I'll get back to you if I have any questions. Cheers Georgefodrv7 said:
PS I think this discussion is great and is weeding out some misconceptions, including a few of my own. That is what a debate/discourses is all about.
Again thanks, may be my opinion needs updating. I never addressed the Egg Subaru conversion, but must admit I did assume from early info and experiences of a few that it was a little more tinker intensive. As it matures it appears service history is proving the engine and installation, which takes time. Thanks for the update. However (you knew it was coming) my goal is good performance, light, simple, reliable and cost effective. The Subaru meets some of these critiera but not all (for me personally). Cost of the Egg FWF kit seems out of line (higher) to the cost of a new Lycoming. Weight is still an issue. As far as reliability I could not be any happier to hear folks are finding their Egg Subaru is reliable. In the end we are all out there, and we want everyone to be safe, never wanting anything bad to happen to a fellow aviator regardless of the engine. Thanks for the update, I will check it out. Merry Christmas Georgerv6ejguy said:
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George,
Just a quick comment on your "attack". I enjoy your insights (dont always agree), but you do have a tendency to get off on a tangent from time to time. Regarding the Mazda, I never said, or implied, that the wankel was a turbine. My comment was simply an observation about the applicablity of turbines to our RVs. You misinterpreted my comment, then went on a multipage rage arguing with yourself. That said, I think your observations about Vne and reasonable power choice are extemely important.
FWIW, all internal combustion engines have a similar cycle that includes intake, compression, power, and exhaust (including the turbines). The biggest difference is that most use reciprocating action (w/ pistons) that create a lot of vibration and mechanical stress, and tend to be sensitive to high rpm operation. Because turbines and rotaries rotate continuously in the same direction, there are some similiar operational characteristics that include high-rpm operation with low vibration, simplicity, and favorable durability and power-to-weight advantages. I'll leave the value judgements to you and others.
I recently attended an EAA presentation by Williams International regarding their work with small turboshaft and jet engines. They pretty much agree that a small turbine is certainly possible, but not really economical for small GA planes like ours (they make engines for cruise missiles, Adamair, etc).
Just a quick comment on your "attack"
. I enjoy your insights (dont always agree), but you do have a tendency to get off on a tangent from time to time. Regarding the Mazda, I never said, or implied, that the wankel was a turbine. My comment was simply an observation about the applicablity of turbines to our RVs. You misinterpreted my comment, then went on a multipage rage arguing with yourself. That said, I think your observations about Vne and reasonable power choice are extemely important. FWIW, all internal combustion engines have a similar cycle that includes intake, compression, power, and exhaust (including the turbines). The biggest difference is that most use reciprocating action (w/ pistons) that create a lot of vibration and mechanical stress, and tend to be sensitive to high rpm operation. Because turbines and rotaries rotate continuously in the same direction, there are some similiar operational characteristics that include high-rpm operation with low vibration, simplicity, and favorable durability and power-to-weight advantages. I'll leave the value judgements to you and others.
I recently attended an EAA presentation by Williams International regarding their work with small turboshaft and jet engines. They pretty much agree that a small turbine is certainly possible, but not really economical for small GA planes like ours (they make engines for cruise missiles, Adamair, etc).
Jconard
Well Known Member
The rotor does not simply spin as a turbine fan does. They follow and eliptical pattern, and an orbit involves the rotor accelerating against housing, an in terms of a vector, it stopps and goes in another direction. They place tremendous stress on the housings. Ever see one blow?
Unlike a spinning turbine. Rotary engines, when tuned to similar specific outputs, HAVE NOT been more reliable than similar piston engines in any application I am aware of, including road racing.
They have a differetn vibration, but certainly not less vibration.
Unlike a spinning turbine. Rotary engines, when tuned to similar specific outputs, HAVE NOT been more reliable than similar piston engines in any application I am aware of, including road racing.
They have a differetn vibration, but certainly not less vibration.
fodrv7
Well Known Member
VMO, MMO. I don't know
VMO (Velocity Max Operating) is the equivalent of VNE.
MMO (Max Mach Operating) is maximum speed in relation to MACH 1.
So Barry that answers your question. But I can?t help myself.
VMO is usually around 330KT IAS for a Heavy Jet.
MMO is usually around Mach 0.85 for a Heavy Jet. ie 85% of the Speed of Sound.
The Speed of Sound = 661KT at ISA Sea Level and so Mach 0.85 (85%) is around 560KT
(The Speed of Sound is actually temperature dependant, but lets keep this simple.)
So if you are in an aircraft with a VMO of 330KT and an MMO equivalent to 560KT then the VMO is the limiting speed at Sea Level.
On the climb at around 30000' the TAS for VMO (330KT IAS) becomes higher than MMO and so MMO becomes the limiting speed.
The Barber pole George mentioned is a red striped speed limit at the top of the airspeed indicator and when MMO is limiting the Barber Pole slides down to obscure all IAS which will be higher than the MMO, which is now the limiting speed.
All of which is irrelevant to Rvs. But as my RV-7 has been at the paint shop for three weeks and they haven't yet picked up the sand paper, I am sitting here with no more rivets to drive or GRP to sand (thank God) and am easily distracted.
My apologies.
But I won't be able to avoid flying the aircraft I built much longer.
January?
Pete.
VMO (Velocity Max Operating) is the equivalent of VNE.
MMO (Max Mach Operating) is maximum speed in relation to MACH 1.
So Barry that answers your question. But I can?t help myself.
VMO is usually around 330KT IAS for a Heavy Jet.
MMO is usually around Mach 0.85 for a Heavy Jet. ie 85% of the Speed of Sound.
The Speed of Sound = 661KT at ISA Sea Level and so Mach 0.85 (85%) is around 560KT
(The Speed of Sound is actually temperature dependant, but lets keep this simple.)
So if you are in an aircraft with a VMO of 330KT and an MMO equivalent to 560KT then the VMO is the limiting speed at Sea Level.
On the climb at around 30000' the TAS for VMO (330KT IAS) becomes higher than MMO and so MMO becomes the limiting speed.
The Barber pole George mentioned is a red striped speed limit at the top of the airspeed indicator and when MMO is limiting the Barber Pole slides down to obscure all IAS which will be higher than the MMO, which is now the limiting speed.
All of which is irrelevant to Rvs. But as my RV-7 has been at the paint shop for three weeks and they haven't yet picked up the sand paper, I am sitting here with no more rivets to drive or GRP to sand (thank God) and am easily distracted.
My apologies.
But I won't be able to avoid flying the aircraft I built much longer.
January?
Pete.
Mike S
Senior Curmudgeon
Mazda vs. turbine
The Mazda rotary engine uses rotors to do the same job as pistons in a "traditional" recip ingine. The rotors run on an eccentric shaft, which does the same job as crankshaft in our "traditional" engine-----it moves the rotor side to side in relation to the crand centerline, and up and down, and all points of the compass-------------and to add to that, the rotor has a gear that is meshed with a fixed gear in the side housing------------which causes the rotor to spin on the eccentric shaft as it is being displaced away from and then back toward the crank centerline.
What this all adds up to is wierd vibrations, and strange harmonics.This caused things to fatigue and brake, and then when you add the dics loads (vastly different than the loads imposed in an auto drivetrain) of a propeller, things get REALLY mixed up.
Dont get me wrong, I have owned and loved a rx-7, changed out the 12a for a 13b, and hot rodded that----------they make a lot of power, and run really smooth--------as percived by our butt in the seat----------but they do create vibration and harmonic problems that any self respecting turbine would self destruct at.
Good thread though----------------
Mike
The Mazda rotary engine uses rotors to do the same job as pistons in a "traditional" recip ingine. The rotors run on an eccentric shaft, which does the same job as crankshaft in our "traditional" engine-----it moves the rotor side to side in relation to the crand centerline, and up and down, and all points of the compass-------------and to add to that, the rotor has a gear that is meshed with a fixed gear in the side housing------------which causes the rotor to spin on the eccentric shaft as it is being displaced away from and then back toward the crank centerline.
What this all adds up to is wierd vibrations, and strange harmonics.This caused things to fatigue and brake, and then when you add the dics loads (vastly different than the loads imposed in an auto drivetrain) of a propeller, things get REALLY mixed up.
Dont get me wrong, I have owned and loved a rx-7, changed out the 12a for a 13b, and hot rodded that----------they make a lot of power, and run really smooth--------as percived by our butt in the seat----------but they do create vibration and harmonic problems that any self respecting turbine would self destruct at.
Good thread though----------------
Mike
gmcjetpilot
Well Known Member
Don't pull the wings off, it will ruin you day
Wrapping it up
Bygones to all and glad we sorted this all out, great info everyone. I love a good beat down, it feels so good when it stops.
To make the debate about a single Vne limit vs. a Vne range (of lower IAS for higher altitude) relevant to RV's, be careful. I am left with the write up from the F-16/RV-4 pilot who dove too fast from altitude. http://www.vansaircraft.com/pdf/hp_limts.pdf (last page)
VNE and Safety
It gets to a point of regulation, aerodynamics and what is really going on specifically to our RV's. Yes I do think you should be aware of a the lower IAS vs. Vne at altitude. Regardless of how a factory (light) planes or transport jets are certified we need to be aware that the relation to flutter and TAS.
Reading your Australian regulations, and the equivalent US regs for normal, utility and transport aircraft that there is a process to make sure that Vne/Vmo/Mmo is not exceeded for all normal flight maneuvers throughout out the envelope. No need to get into it, but needless to say that whether a Jet has a moving barbber pole or Beachcraft has a single Vne (IAS) is not as important to understanding our RV's. They (RV's) are experimental and not really tested. So unless you run your RV up to 220mph IAS at a high altitude, you don't know what will happen. The conservative thing to do is fly at lower IAS at altitude so TAS does not exceed Vne. As we all agree that is not an issue in level flight with an ATMO piston engine, but watch the high dive.
Cobra thanks for the info, now get your turbine, I mean Rotary flying. When you get her flying post lots of pictures. Yes I get on a rant and rave, but I am back on my meds and feeling much better now.
I LIVE IN THE LAND DOWN UNDER
Thanks for the custom picture fodrv7, I thought you where smart, but seeing you standing out there on the wing (I assume its you) with out a net, makes me wounder. I checked my B757/767 manual for airspeed limits and it just says: "Observe IAS/Mach speed indicator limits" That is what is says and the only limit airspeeds are in non-normal procedures.
Boeing and most US airlines have got away from memorizing speeds, placards that are displayed and other useless data (stuff you can't do anything about or really matters to actual flying). It was OLD SCHOOL to be able to memorize the diameter of the fuel line. Some airlines still insist you regurgitate every number in the manual. Boeing's solution was to take the numbers out of the manuals, for better or worse. SO during an oral you don't need to regurgitate numbers (you know the ones you will forget later anyway). The implication to not having a single Vmo/Mmo to memorize is that your flight instrument or FMC displays them.
Cheers All George
Wrapping it up
Bygones to all and glad we sorted this all out, great info everyone. I love a good beat down, it feels so good when it stops.
To make the debate about a single Vne limit vs. a Vne range (of lower IAS for higher altitude) relevant to RV's, be careful. I am left with the write up from the F-16/RV-4 pilot who dove too fast from altitude. http://www.vansaircraft.com/pdf/hp_limts.pdf (last page)
VNE and Safety
It gets to a point of regulation, aerodynamics and what is really going on specifically to our RV's. Yes I do think you should be aware of a the lower IAS vs. Vne at altitude. Regardless of how a factory (light) planes or transport jets are certified we need to be aware that the relation to flutter and TAS.
Reading your Australian regulations, and the equivalent US regs for normal, utility and transport aircraft that there is a process to make sure that Vne/Vmo/Mmo is not exceeded for all normal flight maneuvers throughout out the envelope. No need to get into it, but needless to say that whether a Jet has a moving barbber pole or Beachcraft has a single Vne (IAS) is not as important to understanding our RV's. They (RV's) are experimental and not really tested. So unless you run your RV up to 220mph IAS at a high altitude, you don't know what will happen. The conservative thing to do is fly at lower IAS at altitude so TAS does not exceed Vne. As we all agree that is not an issue in level flight with an ATMO piston engine, but watch the high dive.
Cobra thanks for the info, now get your turbine, I mean Rotary flying.
When you get her flying post lots of pictures. Yes I get on a rant and rave, but I am back on my meds and feeling much better now.I LIVE IN THE LAND DOWN UNDER
Thanks for the custom picture fodrv7, I thought you where smart, but seeing you standing out there on the wing (I assume its you) with out a net, makes me wounder.
I checked my B757/767 manual for airspeed limits and it just says: "Observe IAS/Mach speed indicator limits" That is what is says and the only limit airspeeds are in non-normal procedures. Boeing and most US airlines have got away from memorizing speeds, placards that are displayed and other useless data (stuff you can't do anything about or really matters to actual flying). It was OLD SCHOOL to be able to memorize the diameter of the fuel line. Some airlines still insist you regurgitate every number in the manual. Boeing's solution was to take the numbers out of the manuals, for better or worse. SO during an oral you don't need to regurgitate numbers (you know the ones you will forget later anyway). The implication to not having a single Vmo/Mmo to memorize is that your flight instrument or FMC displays them.
Cheers All George
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gmcjetpilot
Well Known Member
No different engine I think
http://www.mistral-engines.com/
I noticed they do a lot of airshows and no engines flying. I am going to predict this never makes it to market. The cost, weight, installation and fuel burn are all going to conspire to put Mistral efforts under. (Please send the flames, Nomex suit on), but it has been two years since they flew and the (actual) flight test data is.......where? Its a bad sign. Trust me if it was faster, lighter and more efficient we would know. It is really a Mazda 13B engine, nothing new. All Mazda fans please calm down, I think Mazda rocks, I just think Lycoming rocks more.
G
I think you are mistaken with the Minstrel, a rotary based engine reduction drive from a German company. No news from them either in years.alanrv8 said:
http://www.mistral-engines.com/
I noticed they do a lot of airshows and no engines flying. I am going to predict this never makes it to market. The cost, weight, installation and fuel burn are all going to conspire to put Mistral efforts under. (Please send the flames, Nomex suit on), but it has been two years since they flew and the (actual) flight test data is.......where? Its a bad sign. Trust me if it was faster, lighter and more efficient we would know. It is really a Mazda 13B engine, nothing new. All Mazda fans please calm down, I think Mazda rocks, I just think Lycoming rocks more.
G
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cjensen
Well Known Member
i would agree with george. what you are probably thinking of is mistral has a turbo arrow they converted to their rotary in daytona beach. as far as i know (which isn't much) no one has ever put a turbine on an arrow.
i'm a player in the rotary power game, but i do tend to agree with george on mistral. i hope they make it, but their product is really expensive, and they're having a hard time getting people to catch on.
however, if you check their website here, you'll see pics from a guy named steve thomas. he is building a glasair rg II with the mistral, and seems very pleased. the pics are from oct '05, and i have no other updates. we shall see!
i'm a player in the rotary power game, but i do tend to agree with george on mistral. i hope they make it, but their product is really expensive, and they're having a hard time getting people to catch on.
however, if you check their website here, you'll see pics from a guy named steve thomas. he is building a glasair rg II with the mistral, and seems very pleased. the pics are from oct '05, and i have no other updates. we shall see!
Rotary10-RV
Well Known Member
gmcjetpilot said:I think you are mistaken with the Minstrel, a rotary based engine reduction drive from a German company. No news from them either in years.
http://www.mistral-engines.com/
I noticed they do a lot of airshows and no engines flying. I am going to predict this never makes it to market. The cost, weight, installation and fuel burn are all going to conspire to put Mistral efforts under. (Please send the flames, Nomex suit on), but it has been two years since they flew and the (actual) flight test data is.......where? Its a bad sign. Trust me if it was faster, lighter and more efficient we would know. It is really a Mazda 13B engine, nothing new. All Mazda fans please calm down, I think Mazda rocks, I just think Lycoming rocks more.
G
George,
Mistral is flying now WITH competitive fuel burn and getting better all the time. The rotary will operate with much leaner mixtures than anybody originally expected and Mistral is using this to program the EFI. They are Swiss company, not German though that hardly matters. Their engine is in the certification process and looks very competitive compared new-to-new. Hp is higher than Lycs for the same weight now or HP to weight is better using very conservitive numbers. Their price is competitive with other certified engines of the same output. I believe they will succeed. I don't conside this a flame, so take off your nomex underware. Mistral has also agreed to sell portions of the certified package to rotary homebuilders. I think this will help offset cost of development and help the certified package along.
Don't really care if Lycoming is your choice, others are looking for something different. I be glad to show you the layout for My 20B RV-10 when finished in Solidworks. I believe I can finish the package for considerably less than I can get a new or even a used IO-540 in the air. Time will tell, and I'll report the totals honestly when I'm finished.
Rotary10-RV
Bill Jepson
gmcjetpilot
Well Known Member
Thanks for the info
However I have a open mind and hard flight test numbers by an independent party (like yourself) will prove this one way or the other. As far as weight the power sport rotary kits weigh about 50-75 lbs more I recall than a similar powered Lycon RV. (I don't recall but it was lighter than the Subaru engines). How Mistral gets the weight down I don't know, but that is easy to verify when there are some finished examples.
As you said "Time will tell, and I'll report the totals honestly when I'm finished." That RV-10 project sounds like FUN. It must be a challenge and very satisfying doing something cool and different. My hat is off to you. Thanks again for the info. George
PS Dynacam: I had seen it at airshows (80's early 90's?) and it was interesting. Like a Lycoming with horizontal cylinder in paris left to right, tied together, running a rod back and forth that drove a groove or cam on the crank shaft. What happened to them? BUT they are again totally differnt than a turbine or rotary.
Thanks for the info. I hope they have great success, and look forward to seeing them add another competitive choice in the market. The fuel economy and rotary thing I don't get, but we shall see. Due to the shape of the combustion chamber and physical limitation of rotaries they are historically notorious for not being supper fuel efficient. Since they are based on the 13B Mazda block I guess their claim to fuel efficiency, greater than every one else, power sport, real world solutions, is lean mixture using their EFI. Interesting.Rotary10-RV said:
However I have a open mind and hard flight test numbers by an independent party (like yourself) will prove this one way or the other. As far as weight the power sport rotary kits weigh about 50-75 lbs more I recall than a similar powered Lycon RV. (I don't recall but it was lighter than the Subaru engines). How Mistral gets the weight down I don't know, but that is easy to verify when there are some finished examples.
As you said "Time will tell, and I'll report the totals honestly when I'm finished." That RV-10 project sounds like FUN. It must be a challenge and very satisfying doing something cool and different. My hat is off to you. Thanks again for the info. George
PS Dynacam: I had seen it at airshows (80's early 90's?) and it was interesting. Like a Lycoming with horizontal cylinder in paris left to right, tied together, running a rod back and forth that drove a groove or cam on the crank shaft. What happened to them? BUT they are again totally differnt than a turbine or rotary.
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Source for PT6 Engines
I know that these are way to big for RVs, but in case anyone is interested...
My company has over 200 PT6-20 engines in sealed containers. See the link below for more info:
Dynamic Aviation
I know that these are way to big for RVs, but in case anyone is interested...
My company has over 200 PT6-20 engines in sealed containers. See the link below for more info:
Dynamic Aviation
Mike S
Senior Curmudgeon
Dynacam
George, I thinkyou are getting your engines confused.
What you seem to be describing is known as a Scotch yoke engine. They are Horozontantly opposed like a Lyc or Cont or VW etc. Cylinders run at right angle to crank, use a one piece rod that attaches to both pistons, and the crank pin rides in a slot in the rod.
The Dynacam uses a cylinder arrangement like someone posted above--------bullet chambers in a revolver. two sets of them, an a common shaft that is the engines "crankshaft". Pistons are long double ended things with a slot in it that drives the "wavy disc" looking cam (to impart the linier motion of the pistons and change it to rotational motion of the output shaft), as the pistons oscillate back and forth between the two combustion chambers at the ends of each cylinder.
Odd thingie, looks like a turbine at first glance.
Mike
George, I thinkyou are getting your engines confused.
What you seem to be describing is known as a Scotch yoke engine. They are Horozontantly opposed like a Lyc or Cont or VW etc. Cylinders run at right angle to crank, use a one piece rod that attaches to both pistons, and the crank pin rides in a slot in the rod.
The Dynacam uses a cylinder arrangement like someone posted above--------bullet chambers in a revolver. two sets of them, an a common shaft that is the engines "crankshaft". Pistons are long double ended things with a slot in it that drives the "wavy disc" looking cam (to impart the linier motion of the pistons and change it to rotational motion of the output shaft), as the pistons oscillate back and forth between the two combustion chambers at the ends of each cylinder.
Odd thingie, looks like a turbine at first glance.
Mike
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N395V
Well Known Member
gmcjetpilot
Well Known Member
Yep Confuused again
, but in my minds eye, as I was thinking about it, I was thinking of what Milt posted above, I just discribed it poorly. Anyway I think they flew the thing, what happend to it? G
Yep you are right I was confused (again)Mike S said:
, but in my minds eye, as I was thinking about it, I was thinking of what Milt posted above, I just discribed it poorly. Anyway I think they flew the thing, what happend to it? G
