Van's Air Force
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Why is aviation so slow in technology?
- Thread starter bret
- Start date
Bob, you are absolutely right, I just didn't want to go into the details since we were talking about engines performance... But thanks to put it all out for the others!
A lot of pilots don't know those information and sometimes thinks that they are getting more performance by pushing their prop speed to the limit by "tweeking" their governor but in fact they are only thinking they are going faster because of the added noise and are in fact creating more stress on the prop and the engine!
You are absolutely right with the information you provided regarding the Rotax 912... For having worked on them in the past, they are nice and powerful small engine, but to compare the weight of the 912 to a io 233 lycoming, you would need to take into consideration also the added weight of the coolant cooler, the coolant tank and the gearbox... I would be curious to know the final weight of an installed 912 vs a io233!?
Problem with the rotax is their size for now, they need to build a Rotax powerful enough for a RV9...
If I would be building a RV12, I think personally I would go toward a Rotax 912!
Change our mind set; yep you are right, problem is, it takes time and money to develop new technologies and get them FAA approved... General Aviation does not generate enough money for this to happen!
In the big guns thought it's different, just take a look at the new P&W that will power the new Bombardier C Series, it is a geared turbofan!
http://en.wikipedia.org/wiki/Pratt_&_Whitney_PW1000G
http://www.purepowerengine.com/
Sure looks interesting!
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You are absolutely right with the information you provided regarding the Rotax 912... For having worked on them in the past, they are nice and powerful small engine, but to compare the weight of the 912 to a io 233 lycoming, you would need to take into consideration also the added weight of the coolant cooler, the coolant tank and the gearbox... I would be curious to know the final weight of an installed 912 vs a io233!?.
* That is a really good point. So I crunched the numbers. The Rotax with EVERYTHING including water (less 3.5 qts of oil) comes in at 150.5 lbs. The Lyco (less 5 qts of oil) comes in at 213 lbs. Rotax less oil is 62.5 lbs lighter.
Problem with the rotax is their size for now, they need to build a Rotax powerful enough for a RV9...
If I would be building a RV12, I think personally I would go toward a Rotax 912!
* Yeah, I wish Rotax would have continued with the 150hp V6 project.
Change our mind set; yep you are right, problem is, it takes time and money to develop new technologies and get them FAA approved... General Aviation does not generate enough money for this to happen!
* True and it is a real shame.
In the big guns thought it's different, just take a look at the new P&W that will power the new Bombardier C Series, it is a geared turbofan!
http://en.wikipedia.org/wiki/Pratt_&_Whitney_PW1000G
http://www.purepowerengine.com/
Sure looks interesting![/QUOTE]
* That is a really good point. So I crunched the numbers. The Rotax with EVERYTHING including water (less 3.5 qts of oil) comes in at 150.5 lbs. The Lyco (less 5 qts of oil) comes in at 213 lbs. Rotax less oil is 62.5 lbs lighter.
Problem with the rotax is their size for now, they need to build a Rotax powerful enough for a RV9...
If I would be building a RV12, I think personally I would go toward a Rotax 912!
* Yeah, I wish Rotax would have continued with the 150hp V6 project.
Change our mind set; yep you are right, problem is, it takes time and money to develop new technologies and get them FAA approved... General Aviation does not generate enough money for this to happen!
* True and it is a real shame.
In the big guns thought it's different, just take a look at the new P&W that will power the new Bombardier C Series, it is a geared turbofan!
http://en.wikipedia.org/wiki/Pratt_&_Whitney_PW1000G
http://www.purepowerengine.com/
Sure looks interesting![/QUOTE]
frankh
Well Known Member
An interesting experiment would be to measure the the flowrate and temperature of the discharge air temperature from the cowl. Two identical airplanes flying at the same speed, one with water cooling the other with air. The basic question is,,How efficient is each style of engine at heating the cooling air.
The increased surface area of the radiator would in theory provide presumably provide an advantage, the question would be if the if this is enough to compensate for the higher cyl head temps of the air cooled motor.
Actually it would be easier to do the fly off between the Eggenfelner airplane and an identical LYC with an accurate fuel flow meter.
Funny I think we been here before.
I think this comes down to the sense that Van was right..I.e we think there should be something better than the old clunker, but so far we've never seen it.
Anedotally a Lyc running LOP, autofuel with electronic ignition is a pretty darned fuel efficient motor.
Frank
We're getting closer.....
Myself and 20 or so Wilksch WAM 120 diesel owners might beg to differ.
I now have 320 hours on mine, and there is at least one '9A in the UK with well over 500 hours. I'm not sure what the rest have, but, as far as I know, we're all pretty happy with these engines.
I paid no more for mine than I would have paid for a Lyc O-235, and my '9 performs on par with the O-235-powered '9, while weighing less, and using less fuel. And I can burn diesel or Jet A.
I have had no trouble at all with my engine so far. I fly it regularly, and it requires no "babying" - just get in, heat the glow plugs, start it, and go. No priming, no carb heat, no mixture, no mags, no electricity required to run, hyd CS prop. So far, there has been no downside (unless a little smoke on takeoff bothers you!).
Ross, you are right, there are improvements to be made (namely a higher HP engine), but the WAM is pretty good. I would much rather be flying behind it than any other avgas/mogas engine I've flown behind. As so many have stated, developing a new aircraft engine is a VERY costly and time-consuming effort, with not many rewards, thanks to a small market, liability, and so on.
Kurt Goodfellow
RV9 / WAM 120 diesel, 320 hours.
Myself and 20 or so Wilksch WAM 120 diesel owners might beg to differ.
I now have 320 hours on mine, and there is at least one '9A in the UK with well over 500 hours. I'm not sure what the rest have, but, as far as I know, we're all pretty happy with these engines.
I paid no more for mine than I would have paid for a Lyc O-235, and my '9 performs on par with the O-235-powered '9, while weighing less, and using less fuel. And I can burn diesel or Jet A.
I have had no trouble at all with my engine so far. I fly it regularly, and it requires no "babying" - just get in, heat the glow plugs, start it, and go. No priming, no carb heat, no mixture, no mags, no electricity required to run, hyd CS prop. So far, there has been no downside (unless a little smoke on takeoff bothers you!).
Ross, you are right, there are improvements to be made (namely a higher HP engine), but the WAM is pretty good. I would much rather be flying behind it than any other avgas/mogas engine I've flown behind. As so many have stated, developing a new aircraft engine is a VERY costly and time-consuming effort, with not many rewards, thanks to a small market, liability, and so on.
Kurt Goodfellow
RV9 / WAM 120 diesel, 320 hours.
Actually just measuring the cowling exit air temps wouldn't tell us what we really need to know here which is the overall efficiency of the system and to do that we really need two close to identical RVs, same prop and the different engine designs, fly them side by side, switch tanks and fly for 1.5 hours, switch tanks, land and see who burned less fuel on top up.
From all the feedback from customers with atmo Egg conversions, it is clear that fuel flows are higher than a comparable Lycoming at the same TAS. The two modified turbo STIs are noticeably more efficient and repeated tests with calibrated FF meters and the switch tanks/ time/ top up method both show very comparable data to a Lycoming setup. These invariably do not use the same prop though as both STIs use electric MTs and the Lycoming ones don't so this is not totally apples to apples.
As far as the WAM engines go, while I'm VERY impressed with what they have done with a small team, I still reserve judgement until those 20 engines in service all go 2000-2400 hours without major trouble like an O-235 might and I don't see any better performance or fuel flow with the WAM. O-235 RV9s seem to do about the same speeds and fuel flows LOP. The published SFCs for the 2 engines are very similar as well. I've said it before, a few hundred hours on a few engines does not tell us how good an engine design might be long term and for overall operating costs. At the moment, it is encouraging at least and that is a very good start.
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WAM
Point taken. We've got to start somewhere.
With regard to the O-235 being as efficient as the WAM, you may be close once you're in cruise, LOP. But, if you recall when Van's tested the factory RV9A against the WAM, we did a one hour flight, side by side "same day, same way". Actually we (Marc Cook and I), were about 70 lb heavier than Ken K and his brother. Ken and I followed the exact same flight profile, and I burned almost 2 gallons less than he did. The whole purpose of the flight was to compare fuel burn. Ken encouraged me to do everything I could to optimize fuel efficiency, and that he would do the same with the Lyc. It wasn't apples to apples, because the factory '9A had an O-320, but I don't know how many times I've read in this forum (including Ross's posts) that any Lycoming run LOP, throttled back to the lower speeds of the WAM or O-235, would achieve the same efficiency.
I only had 85 hours on the plane at that time, but since then, I've discovered that my efficiency gets better with altitude, thanks to the turbo. If I had that flight to do over again, I think I could have done even better if I flew higher, and made the Lyc burn more fuel in the climb.
As I've said before: when you consider the whole flight profile, the diesel comes out on top, even the less-efficient ones like the WAM.
I agree with what many have said about liquid cooling. If done correctly, it should be more efficient than air cooled. Mine is nowhere near correct yet. It works well, but I know it could be much better. I'm working on it, little by little. But I just can't stop flying long enough to tear it down and make some of the changes that need to be made!
Kurt
As far as the WAM engines go, while I'm VERY impressed with what they have done with a small team, I still reserve judgement until those 20 engines in service all go 2000-2400 hours without major trouble like an O-235 might and I don't see any better performance or fuel flow with the WAM. O-235 RV9s seem to do about the same speeds and fuel flows LOP. The published SFCs for the 2 engines are very similar as well. I've said it before, a few hundred hours on a few engines does not tell us how good an engine design might be long term and for overall operating costs. At the moment, it is encouraging at least and that is a very good start.
Point taken. We've got to start somewhere.
With regard to the O-235 being as efficient as the WAM, you may be close once you're in cruise, LOP. But, if you recall when Van's tested the factory RV9A against the WAM, we did a one hour flight, side by side "same day, same way". Actually we (Marc Cook and I), were about 70 lb heavier than Ken K and his brother. Ken and I followed the exact same flight profile, and I burned almost 2 gallons less than he did. The whole purpose of the flight was to compare fuel burn. Ken encouraged me to do everything I could to optimize fuel efficiency, and that he would do the same with the Lyc. It wasn't apples to apples, because the factory '9A had an O-320, but I don't know how many times I've read in this forum (including Ross's posts) that any Lycoming run LOP, throttled back to the lower speeds of the WAM or O-235, would achieve the same efficiency.
I only had 85 hours on the plane at that time, but since then, I've discovered that my efficiency gets better with altitude, thanks to the turbo. If I had that flight to do over again, I think I could have done even better if I flew higher, and made the Lyc burn more fuel in the climb.
As I've said before: when you consider the whole flight profile, the diesel comes out on top, even the less-efficient ones like the WAM.
I agree with what many have said about liquid cooling. If done correctly, it should be more efficient than air cooled. Mine is nowhere near correct yet. It works well, but I know it could be much better. I'm working on it, little by little. But I just can't stop flying long enough to tear it down and make some of the changes that need to be made!
Kurt
Ron Lee
Well Known Member
This comment has been applied to avgas versus avgas engines.....not avgas to diesel.
A friend has a Golf TDI diesel that gets 50 MPG. Am I to conclude that diesel engines are in general more fuel efficient than gasoline?
If you are using a WAM 120, my gut view is why install a 120 HP powerplant in an aircraft that accepts 160 HP? The Tim Allen principle is solid. Enjoy what you have but that powerplant is not likely to be other than a ultra-minor engine of choice. Plus you will have to accept that an RV so equipped will have close to zero resale value...or only among a rare (very small) number of potential buyers.
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NDrv8r
Well Known Member
Avgas vs diesel
Actually, the way I read it, Ross was comparing the economy of the WAM diesel to the avgas O-235, and I just wanted to set the record straight. Diesels are more fuel efficient than gasoline engines. I know of no exceptions, although there may be a few that I'm not aware of. Does that mean that diesels are better than gas engines in airplanes? Ross is right, more development is required to find the answer. But in my case, so far the diesel has been better.
And, yes, your "gut view" is probably right. Why indeed install a 120 hp where a 160 is acceptable? For me, it was because there wasn't a 160 hp diesel available - and the RV9 airframe also accepts a 118 hp engine. Since I understood (and still do) the benefits and inevitability of aerodiesels, I was willing to accept some risks (and this includes financial risk) in order to experiment. There are some of us still out here who are willing to experiment in order to help develop better technologies.
Close to zero resale value? I'm not so sure. I have been amazed at the interest this engine/airframe combination has generated. Most aviators I've spoken with know that avgas as we know it is eventually going to be phased out. They also know Jet A is the most available and preferred aviation fuel worldwide. It's no stretch for most people to understand that diesels will a big part of aviation in the future. In the presentations I have given at forums and EAA chapter meetings, people have been very interested to see what lies ahead. Many are familiar with the amazing progress in automotive diesel technology; they know that it's just a matter of time until this technology is harnessed for GA.
If I offered it for sale today, would it bring what a traditional-powered RV would? Maybe not. Probably not. But I didn't built it to sell. I got what I wanted - and then some.
If you're concerned about resale value, check the "traditional engine" forum, and stick with the tried and proven, same 'ol, same ol. Nothing wrong with that.
Kurt
Actually, the way I read it, Ross was comparing the economy of the WAM diesel to the avgas O-235, and I just wanted to set the record straight. Diesels are more fuel efficient than gasoline engines. I know of no exceptions, although there may be a few that I'm not aware of. Does that mean that diesels are better than gas engines in airplanes? Ross is right, more development is required to find the answer. But in my case, so far the diesel has been better.
And, yes, your "gut view" is probably right. Why indeed install a 120 hp where a 160 is acceptable? For me, it was because there wasn't a 160 hp diesel available - and the RV9 airframe also accepts a 118 hp engine. Since I understood (and still do) the benefits and inevitability of aerodiesels, I was willing to accept some risks (and this includes financial risk) in order to experiment. There are some of us still out here who are willing to experiment in order to help develop better technologies.
Close to zero resale value? I'm not so sure. I have been amazed at the interest this engine/airframe combination has generated. Most aviators I've spoken with know that avgas as we know it is eventually going to be phased out. They also know Jet A is the most available and preferred aviation fuel worldwide. It's no stretch for most people to understand that diesels will a big part of aviation in the future. In the presentations I have given at forums and EAA chapter meetings, people have been very interested to see what lies ahead. Many are familiar with the amazing progress in automotive diesel technology; they know that it's just a matter of time until this technology is harnessed for GA.
If I offered it for sale today, would it bring what a traditional-powered RV would? Maybe not. Probably not. But I didn't built it to sell. I got what I wanted - and then some.
If you're concerned about resale value, check the "traditional engine" forum, and stick with the tried and proven, same 'ol, same ol. Nothing wrong with that.
Kurt
Great thread. I'd like to answer a few unasked questions...
First off, piston ring swept area is still the number one friction related issue facing piston engines. Simple geometry dictates that larger bore/stroke (fewer cylinder) engines have less piston ring swept area, when compared by displacement. Friction is a very large factor in overall BSFC. The lowly injected Lycoming still achieves world class BSFC numbers. Big bore, low RPM and air cooling are all factors in good efficiency.
Second, Modern 4 valve cylinder heads use tumble to create turbulence, allowing a high compression ratio. The port angle, port velocity, engine RPM and valve included angles are critical in regards to detonation resistance. This unfortunately increases the size, weight and complexity of the engines.
Third, Exhaust Gas Recirculation, as used on most modern automotive engines, dilutes the fuel/air mixture considerably, and therefore lowers combustion temperatures. With significant reduction in detonation and octane requirements.
Fourth, As mentioned above, small bore, high RPM engines are far less prone to detonation. A 250cc 4 stroke motocrosser runs 12.5 to 1 compression ratio without need for high octane fuel. At a peak of 13,500RPM, detonation is much less of a concern. 87 octane will perform just fine.
Diesels are thermally more efficient, mostly due to the very high compression ratio. BUT, diesel/jet fuel is more dense. When you look at BSFC by wt, the diesel is less superior. In fact, experimental modern gasoline and yes, even Ethanol engines can exceed a typical diesels thermal efficiency! Consider that the fuel we consume has not just volume, but weight. When it comes down to it, (other than cost) the weight is what really matters. How far can you fly with 250 pounds of fuel? Jet A is 12% heavier per gallon.
In a highly loaded, hard working engine, piston heat must go somewhere. The piston rings play a large role in heat transfer. This dictates the piston ring dimensions. It's a major reason why automotive style, 1mm compression rings are not possible on a Lycoming. The piston would rapidly overheat. Regardless of external cooling.
Therein lies the genius of a modern air cooled Lycoming, Continental, or even Pratt radial. They are lightweight, simple, thermally efficient engines with superb BSFC numbers, capable of operating on lightweight fuel, with low cooling drag requirements, while achieving acceptable reliability and lifespan.
The bottom line is that the engineers in the '30's understood what was necessary to achieve the necessary performance, payload capability, speed, range and reliability balance. Your Chevy Small block will make the HP, but it won't have the low cooling drag, or the low BSFC and light weight necessary for long range with significant payload.
First off, piston ring swept area is still the number one friction related issue facing piston engines. Simple geometry dictates that larger bore/stroke (fewer cylinder) engines have less piston ring swept area, when compared by displacement. Friction is a very large factor in overall BSFC. The lowly injected Lycoming still achieves world class BSFC numbers. Big bore, low RPM and air cooling are all factors in good efficiency.
Second, Modern 4 valve cylinder heads use tumble to create turbulence, allowing a high compression ratio. The port angle, port velocity, engine RPM and valve included angles are critical in regards to detonation resistance. This unfortunately increases the size, weight and complexity of the engines.
Third, Exhaust Gas Recirculation, as used on most modern automotive engines, dilutes the fuel/air mixture considerably, and therefore lowers combustion temperatures. With significant reduction in detonation and octane requirements.
Fourth, As mentioned above, small bore, high RPM engines are far less prone to detonation. A 250cc 4 stroke motocrosser runs 12.5 to 1 compression ratio without need for high octane fuel. At a peak of 13,500RPM, detonation is much less of a concern. 87 octane will perform just fine.
Diesels are thermally more efficient, mostly due to the very high compression ratio. BUT, diesel/jet fuel is more dense. When you look at BSFC by wt, the diesel is less superior. In fact, experimental modern gasoline and yes, even Ethanol engines can exceed a typical diesels thermal efficiency! Consider that the fuel we consume has not just volume, but weight. When it comes down to it, (other than cost) the weight is what really matters. How far can you fly with 250 pounds of fuel? Jet A is 12% heavier per gallon.
In a highly loaded, hard working engine, piston heat must go somewhere. The piston rings play a large role in heat transfer. This dictates the piston ring dimensions. It's a major reason why automotive style, 1mm compression rings are not possible on a Lycoming. The piston would rapidly overheat. Regardless of external cooling.
Therein lies the genius of a modern air cooled Lycoming, Continental, or even Pratt radial. They are lightweight, simple, thermally efficient engines with superb BSFC numbers, capable of operating on lightweight fuel, with low cooling drag requirements, while achieving acceptable reliability and lifespan.
The bottom line is that the engineers in the '30's understood what was necessary to achieve the necessary performance, payload capability, speed, range and reliability balance. Your Chevy Small block will make the HP, but it won't have the low cooling drag, or the low BSFC and light weight necessary for long range with significant payload.
Bob Kuykendall
Well Known Member
Interesting!
Just for grins, I put together a quickie spreadsheet to compare the piston ring swept area of three engines with displacements around 360 in^3:
_______________________________Lyc O-360__Conti O-360__Chevy 350
Bore___________________________5.125______4.438________4
Stroke_________________________4.375______3.875________3.48
Number of cylinders____________4__________6____________8
Displacement (in^3)____________361.01_____359.66_______349.85
Piston ring swept area (in^2)__281.76_____324.16_______349.85
Ratio of swept area
to displacement________________0.78_______0.90_________1.00
(Sorry about the weird formatting, that is the cleanest I could do with the tools at hand).
Swept area is actually not so high on the list and is only one factor. Modern auto engines use thin, low tension moly rings for the most part and much thinner multi weight oils, resulting in lower friction than the clunky stuff on a Lycoming. If you were to motor over a modern 3.5-3.8 auto V6 and a 360 Lycoming over with an electric motor at 2700 and the V6 at 3800-4000 rpm to match hp, I'm willing to bet the V6 has less friction. Comparing a Chevy V8 is hardly fair since it is a much more powerful engine than the Lycoming. You could compare some 2.5L 4 cylinders these days as far as hp and for sure these have less friction than a Lycoming with the same hp.
Automotive engines of the same hp have smaller volumes than an equivalent Lycoming, even with a gearbox. They may have more parts inside but this does not affect reliability. The power density on liquid cooled engines is significantly higher than air cooled engines.
Not sure what octane requirement has to do with anything here. Many high output auto engines run on 87 octane and will certainly run fine on 100LL. The reverse might not be true with a Lycoming unless the CR is 8 to 1 or below. The small, efficient and extensively engineered chambers on auto engines are far superior in this respect. High CRs give higher TE, better BSFCs, lower EGTs and more hp. Liquid cooling allows the higher CRs.
I would not say a Lycoming is hard working. The specific power output is a pitiful 30hp/L. Many stock auto engines are in the 80 to 100hp/L today so about 3 times the specific output. Auto engines use thin rings because they offer better life and control at high rpms along with less friction. They can do this even with triple the specific power output because they are liquid cooled and use very tight clearances on the piston to cylinder which gives much higher heat transfer rates from skirt to bore. They don't overheat because the piston and bore are much cooler than on an air cooled engine.
Finally, we see the turbocharged Subaru engines offering similar speeds and fuel burns as a 360 Lycoming so cooling drag can't be much worse and neither can the BSFCs. The Subaru is not even renown for great fuel economy in the automotive world. I submit than any of the latest DI 11-13 to 1 CR atmo, lightweight auto engines would be lighter and have lower fuel burns than a Lycoming even with a gearbox.
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Piston ring swept area, to the best of my knowledge, (feel free to correct me, engineering classes were years ago) remains the number one issue with regards to internal engine friction. That's clearly why so much effort is put into thin, low tension piston rings. Which are perfect under moderate loads with modest heat transfer requirements. They have been proven to have very short lives under continuous duty heavy load conditions (often resulting in annealed rings and loss of tension). Honda and Subaru conversions are successful as is the Rotax 912. However, at a best of 285g/Kwh SFC, they fall far short of the best injected, air cooled, big bore engines. Don't forget, the application of modern technology to a Lyc, operating lean of peak, results in real world cruise SFC numbers of 225g/Kwh. Exactly the same as the best numbers a Prius engine achieves.
Please understand, I'd love to see an aviation specific, efficient, lightweight, simple, inexpensive modern engine making 200-300HP. I'm certain with modern materials and design, TBO could far exceed legend aircraft engines. So far, nobody has pulled it off.
Of course, I've completely ignored the fact that the lowly Lyc needs foul amounts of cooling fuel on T/O and climb. Good thing your RV climbs to the FL's in mere minutes.
Please understand, I'd love to see an aviation specific, efficient, lightweight, simple, inexpensive modern engine making 200-300HP. I'm certain with modern materials and design, TBO could far exceed legend aircraft engines. So far, nobody has pulled it off.
Of course, I've completely ignored the fact that the lowly Lyc needs foul amounts of cooling fuel on T/O and climb. Good thing your RV climbs to the FL's in mere minutes.
Using your argument then, the swept area of 190hp, 2.5L 4 cylinder automotive engine is a lot lower than a 360 Lycoming- so lower friction.
There is no issue with ring life in modern auto engines which are tested at 100% power for 600 hours + by the factories during validation (some run 1200 hours WOT). We have seen Subarus go 3800+ hours in Gyros in the training environment and many have reached 700-1000 hours now with perfect compression in fixed wing aircraft. Glider towing aircraft with Ford and GM V type engines have demonstrated longer life and much lower overall fuel consumption than the Lycoming engines they replaced.
I submit that the published BSFC figures for Lycoming may be inaccurate as LOP operation results in a noticeable power loss at a given rpm and MAP over best power mixtures. Too many people accept the figures shown on glass as far as % power goes as gospel. Only a true dyno test would give us the real numbers. We have seen several examples now of auto engines matching fuel flow vs. TAS numbers of Lycoming powered examples so something does not add up here.
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The piston ring swept area is not just the matter of simple geometry, it also includes RPM. Your 2.5L 190HP example is a very good one, as the 200HP angle valve Lyc generally produces between 185 and 193HP at 2700RPM in unmodified form. The new GM 2.5L is 190HP at 6200RPM. They are both, effectively moving the same volume of air. One is working much harder to do so. Having just rented a 2012 Malibu for a week, while in recurrent training, I can say, without a doubt, that is one doggy engine, very shy of low end torque and I certainly would not like flying behind one at 6200RPM.
If you think back 20 years, there were hombuilders modifying and yes, even flying Oldsmobile Quad 4 engines. Any guess as to how well and how efficiently they produced the rated 190HP?
Remember, I am not interested in published Lyc numbers. I am interested in what experimental versions of a well built and set up Lyc/Cont engine can achieve. Talk with Klaus for a bit, and the fuel economy/performance ratio he achieves. It's an eye opener, that's for sure.
CAFE Foundation took a Mooney, with a 200HP Lyc, modified the airframe, tuned the engine and achieved some truly stunning improvements.
Lean of peak operations are, in many situations, not only possible, but significant efficiency boosters. Something not readily achieved with automotive based electronic fuel injection.
Maybe the crux of this discussion is simply this: I don't have the answer as to which modern design would be a significant improvement over a well prepped experimental Lyc.
There are many examples of 180-200hp class 2.5L auto engines these days. The new Subaru 4 cylinder produces 197hp from only 2L, naturally aspirated with DI. It is horizontally opposed just like the Lycoming.
You have to remember an O-360 at 75% power cruise is only putting out 135hp so it is pretty easy for a modern 2.5L four to put that out at 4000-4500 rpm- no different than cruising on the Autobahn at 160-180 kmh. Something which millions of cars do every day without problems or reduced life.
Valvetrain friction is a more major concern at high rpms which is why auto engines generally use OHC layouts.
Of course, we have had this discussion here many times before that torque is not an important factor for motivating vehicles- hp is. With the proper gearbox ratio, smaller auto engines easily match the performance of 6L Lycoming engines- again already flight proven in the case the the two 200+ knot STI Subaru RVs. Lower prop rpms seem to easily offset the 2-4% loss through the typical single or twin mesh PSRUs used in most cases.
It's no problem using EFI to run aircraft engines LOP, we've been doing it for over 15 years. EFI can do anything carbs or mechanical injection can do.
Would all this technology offer noticeably better speeds vs. fuel flows in cruise? Probably not to any significant degree in my opinion but we are actually flying stuff today that shows very similar performance so it is no worse. If you roll your own conversion and do it right, it is considerably cheaper than the Lycoming option. Do it wrong and you are certainly in for plenty of headaches. Both ways have been experienced by many people.
As far as the new technology filtering down into clean sheet aviation engine designs, it is unlikely to happen due to financial and liability issues and you are right, there is simply no really compelling reason since there would be minimal gains- simply put, why would anyone bother to spend all that time and money with little return.
You have to remember an O-360 at 75% power cruise is only putting out 135hp so it is pretty easy for a modern 2.5L four to put that out at 4000-4500 rpm- no different than cruising on the Autobahn at 160-180 kmh. Something which millions of cars do every day without problems or reduced life.
Valvetrain friction is a more major concern at high rpms which is why auto engines generally use OHC layouts.
Of course, we have had this discussion here many times before that torque is not an important factor for motivating vehicles- hp is. With the proper gearbox ratio, smaller auto engines easily match the performance of 6L Lycoming engines- again already flight proven in the case the the two 200+ knot STI Subaru RVs. Lower prop rpms seem to easily offset the 2-4% loss through the typical single or twin mesh PSRUs used in most cases.
It's no problem using EFI to run aircraft engines LOP, we've been doing it for over 15 years. EFI can do anything carbs or mechanical injection can do.
Would all this technology offer noticeably better speeds vs. fuel flows in cruise? Probably not to any significant degree in my opinion but we are actually flying stuff today that shows very similar performance so it is no worse. If you roll your own conversion and do it right, it is considerably cheaper than the Lycoming option. Do it wrong and you are certainly in for plenty of headaches. Both ways have been experienced by many people.
As far as the new technology filtering down into clean sheet aviation engine designs, it is unlikely to happen due to financial and liability issues and you are right, there is simply no really compelling reason since there would be minimal gains- simply put, why would anyone bother to spend all that time and money with little return.
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Just to add more fuel to the fire, you can make 450HP from an LS Chevy V8, or 5.0 OHC Ford very easily. Very modern engines with the latest technology with totally different executions (pushrods vs. ohc).
In contrast, however, large over the road trucks that are looking for high HP production for long periods of time, economically, reliable, and for many hours, are running at low rpm (around 1400) and are big displacement (like 900 cubinc inches), but are still producing right at 450HP.
Different operating conditions (or missions) require different solutions, even if the power levels are the same.
Auto engines make the power, but they do it differently than airplane engines. And differently than heavy truck engines. And differently than train engines. There are reasons for that.
Tim
In contrast, however, large over the road trucks that are looking for high HP production for long periods of time, economically, reliable, and for many hours, are running at low rpm (around 1400) and are big displacement (like 900 cubinc inches), but are still producing right at 450HP.
Different operating conditions (or missions) require different solutions, even if the power levels are the same.
Auto engines make the power, but they do it differently than airplane engines. And differently than heavy truck engines. And differently than train engines. There are reasons for that.
Tim
One idea that I've never seen implemented is a diesel conversion of a 6 cylinder Lyc/Cont. The idea would be to install considerably smaller bore diesel cylinders (possibly cast as a 3cyl liquid cooled unit). That way, crankshaft, bearing and rod loading would be equiv.
The 6 cyl firing order and config is ideal for 2 turbo's, one under each bank and intercoolers located above the cylinders in the baffling.
The pushrods would remain, however, they would actuate 4 small valves via forked rockers. Direct injection would be achieved via an accy driven injector pump.
HP to weight could be managed and many existing parts could be used.
It has the promise of increased efficiency, with acceptable power and weight.
The 6 cyl firing order and config is ideal for 2 turbo's, one under each bank and intercoolers located above the cylinders in the baffling.
The pushrods would remain, however, they would actuate 4 small valves via forked rockers. Direct injection would be achieved via an accy driven injector pump.
HP to weight could be managed and many existing parts could be used.
It has the promise of increased efficiency, with acceptable power and weight.
Absolutely right.
As a counter though, the Rotax 912S is lighter and burns about the same fuel as an O-233. Also proven reliable and with long life. Shows that you don't always need to bake the same recipe. A geared, high revving, small engine can do the same job if it is done right. There is a good reason why Van chose this engine for the RV12.
Bob Kuykendall
Well Known Member
So far, I've had two head gasket failures in Subaru cars with EJ25s. Because of their cooling system design, once there is a bubble of exhaust gas in the coolant the circulation stops, and you can't pull ten horsepower out if it without overheating. That's the big reason why the idea of flying behind a Soob motor gives me the willies.
Thanks, Bob K.
Yeah, there are different ways to go to address a common mission, but they are flavors of a recipe, not entirely different recipes. And the important ingredients are not always understood by those outside of the development process (I am not claiming to be an insider).
My vision of the perfect small airplane engine (with all of my personal biases thrown in) would be an aircooled flat 4,direct drive, electronic ignition, direct fuel injected engine with variable air ducts controlled by engine temp and operating condition. It would also have a flat 6 version for the higher power applications and would be targeted at the 160-210HP range for the 4 and 240-320HP range for the 6. I would stay away from force feeding it, just for simplicities' sake.
That's my story and I'm sticking to it.
Tim
I think I agree, in fact, I've been thinking about DI for some time now. Direct injection may improve efficiency on a number of fronts. Including higher CR, better combustion, and reduce the risk of deto to near nil. Plus, 4 small valves could be used, to keep chamber heat losses down. Which, by the way is another positive factor in aircraft engine design. That is, less surface area to reject heat.
And the age old problem of heated fuel causing flooding or vapor lock would be fully eliminated.
The EJ25s are renown for HG problems which is actually due to to the factory not getting the block decks straight. When they are properly resurfaced along with the heads, they never have a problem again but almost every original EJ25 with more than 100,000 miles on it probably has had a bad HG. Interestingly we haven't seen almost any of these in aircraft, possibly due to lower numbers of thermal cycles.
Fortunately EJ22Ts, STIs, EG33s and EZ engines don't seem to have these problems.
Flying behind AD inflicted Lycomings/ ECIs does not give me a warm feeling either.
The original post asked why some of the new automotive technology was so slow to filter down into aviation engines not whether you prefer to fly behind auto or traditional engines. That one has been beaten to death. I think we have established that there would be minimal gains and substantial legal and monetary reasons not to bother.
Let me say, I am again sorry to be drawn into the same old battle again...
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the_other_dougreeves
Well Known Member
Why? Small market and lack of competition. The automotive market is HUGE, which creates competition and real R&D investment. Direct injection turbo gas engines and common rail turbodiesels are all a result of many, many years of R&D and even racing experience.
TODR
TODR
I keep thinking about the Porsche powered Mooney. It was more than 200 pounds heavier, made 17 more HP, required a very expensive composite/kevlar prop (for weight savings) , had a slower top speed and worse cruise fuel economy. It also used none of the promised "cheaper" automotive based internals (they would not hold up) and it only cost $100,000 more than the 201 it compared with.
Orenda is another one. The automotive engine they started with ended up being completely and totally redesigned (many times) to achieve certification.
Orenda is another one. The automotive engine they started with ended up being completely and totally redesigned (many times) to achieve certification.
wolfpack21643
Member
I fly for a Sheriff?s Office and we fly a Zenith 701 with a Rotax 912 aboard. I came from Lycs and Conts., and wanted nothing to do with the Rotax when I was told that?s what I would be flying for a living during my job interview. I told them about my issues with ?that foreign? motor and almost turned the job down. They had me talk to the local ?light sport guru? and he was pretty persuasive about how reliable the Rotax is.
I took the job and demanded to attend a quality tear down school to learn the workings of the engine. I attended a Rotax 912 full tear down maint. School in Mississippi (Ron Smith?s). We spent four days tearing the engines down to the crank and rebuilding them. The class was taught by Ron Smith who has been rebuilding these engines since they came out and the head of engineering for the Rotax Corporation (what a treat). The class was full of full time A&P?s trying to learn the engine and they really took the rare opportunity to jump on an instructor such as the caliber as the head Rotax guy.
One student asked him ?why are these engines so expensive??
His reply went something like this.
?It only cost us about $5000 to actually make the engine (I think he was including labor in that figure also). The rest goes to insurance and legal fees both to fight the FAA and crash incidents?.
He made the comment that they are sued for gross negligence at least 25 times a year world wide. He stated that they had never been found guilty of ?gross negligence? in a court anywhere world wide. He stated that they buy their insurance by the engine sold not a blanket policy. He stated that the insurance company charges $9000 per sold engine on avg.
He was asked about the 6 cylinder engine and his reply was ?you couldn?t afford it. The insurance per engine would be $15,000 on our end?.? Then the legal fees for the FAA and such would add another $10,000 per engine, so you?re looking at 15g for ins., 10g for lawyers, 7g for materials, and 5g for profit. That makes $37,000 for a 160 hp engine. Our market research shows that people wont pay that for a new in design motor that does what is already out there and proven?.
I think that sums it up. It?s a combination of the FAA regulations (lawyers to fight the FAA), Insurance companies (more lawyers) and frivolous law suits (lawyers again). I know that there are some lawyers on here that will take offense to my comments but I got my info from one of the top of the food chain engine company types and a lawyer who confirmed my assumptions (and by the way I?m married to her).
Until the government?s over regulation is slowed up a lot and some sort of tort reform is put into place to keep the crazy law suites at bay, then I think you got what you got.
Example:
If an insurance company knows what their max payout will be and they can average the amount of claims per year then they can knock the rates down a lot. But when they have to build there rainy day fund up for the rare instance where a person fly?s their (your engine name here) into a school because
he forgot to put the oil cap back on the engine during pre-flight and kills several kids and the parents line up and take their $100 million a piece jury issued settlements from the insurance company (because the pilot / owner isn?t worth much) your never going to see cheap engines or other cheap aviation related goods.
I took the job and demanded to attend a quality tear down school to learn the workings of the engine. I attended a Rotax 912 full tear down maint. School in Mississippi (Ron Smith?s). We spent four days tearing the engines down to the crank and rebuilding them. The class was taught by Ron Smith who has been rebuilding these engines since they came out and the head of engineering for the Rotax Corporation (what a treat). The class was full of full time A&P?s trying to learn the engine and they really took the rare opportunity to jump on an instructor such as the caliber as the head Rotax guy.
One student asked him ?why are these engines so expensive??
His reply went something like this.
?It only cost us about $5000 to actually make the engine (I think he was including labor in that figure also). The rest goes to insurance and legal fees both to fight the FAA and crash incidents?.
He made the comment that they are sued for gross negligence at least 25 times a year world wide. He stated that they had never been found guilty of ?gross negligence? in a court anywhere world wide. He stated that they buy their insurance by the engine sold not a blanket policy. He stated that the insurance company charges $9000 per sold engine on avg.
He was asked about the 6 cylinder engine and his reply was ?you couldn?t afford it. The insurance per engine would be $15,000 on our end?.? Then the legal fees for the FAA and such would add another $10,000 per engine, so you?re looking at 15g for ins., 10g for lawyers, 7g for materials, and 5g for profit. That makes $37,000 for a 160 hp engine. Our market research shows that people wont pay that for a new in design motor that does what is already out there and proven?.
I think that sums it up. It?s a combination of the FAA regulations (lawyers to fight the FAA), Insurance companies (more lawyers) and frivolous law suits (lawyers again). I know that there are some lawyers on here that will take offense to my comments but I got my info from one of the top of the food chain engine company types and a lawyer who confirmed my assumptions (and by the way I?m married to her).
Until the government?s over regulation is slowed up a lot and some sort of tort reform is put into place to keep the crazy law suites at bay, then I think you got what you got.
Example:
If an insurance company knows what their max payout will be and they can average the amount of claims per year then they can knock the rates down a lot. But when they have to build there rainy day fund up for the rare instance where a person fly?s their (your engine name here) into a school because
he forgot to put the oil cap back on the engine during pre-flight and kills several kids and the parents line up and take their $100 million a piece jury issued settlements from the insurance company (because the pilot / owner isn?t worth much) your never going to see cheap engines or other cheap aviation related goods.
This fits with my estiates as well. You should be able to profitably build and sell a 4cyl aviation engine for about $5K retail. This would cut over $30K out of the price of a typical factory plane, and almost $20K out of a $70K RV. Interesting isn't it? I'll bet the same is true of props and avionics, and I bet it is likely that the real retail retail price of an RV-like airplane built in an efficient factory should be around $35K to $40K sitting on the showroom floor ready to go. Now THAT would drive serious powertrain and avionics development.
Tim
No way could you build an aircraft or any other 100-180 hp engine for $5,000.00. You are not considering the cost of start up design, manufacturing, labor, testing, etc. Tort law doesn't have anything to do with that. The cost of a start up would be large and have to be included in the cost per engine. It costs more than $5000.00 to simply rebuild a 0-320 Lycoming for a kit built plane, an engine already paid for. Rotax has their costs down because they have paid off their loans, and aren't designing new engines, but starting up a new manufacturing site would be high.
I don't disagree with what you are saying. But what I am saying is, whatever happened in about 1978 through 1983 that caused the GA piston market to go from 17,000 per year to less than 2,000 per year is what caused the problem. Volume changed, then prices changed. It did not happen the other way around.
How many parts are in a 4cyl Lycoming? We are talking here about an engine with:
- Aluminum case - 2 machined castings
- Forged steel crank
- 4 cylinder castings
- 4 head castings, with 8 valves and associated rocker arms, sprins, etc.
- cam and pushrods
- 4 forged alminum pistons and rods
- Then a dead simple carb or fuel injection system and a couple of magnetos
Yes I know there are more parts, but these are the majors and there is not more than about $3,500 worth of parts, retail. I know they actually cost more, but that is what their value is. Max.
The cost drivers are not technical or manufacturing related, it is elsewhere, as others have said. If these roadblocks were removed, a company could profitably sell a Lycoming-like engine (if not clone) for way less than $10k. Period.
At that point GA would be thriving, not dying, and technology would be advancing faster than it is now. This would apply to avionics and props as well.
The greatest side benefit issafety. This would cause overall flying to be cheaper, which means more flight hours for pilots, which means more experience and practice and currency, and higher levels of safety.
Tim
Bob Kuykendall
Well Known Member
Somehow I am not communicating well, which is not unusual. I am not saying that you can do that in today's regulated, litigous environment. I am not even saying that know exactly what the (refulatory or litigous) problem is. I am not a lawyer or a polititian. What I am saying is, if you are of the "you get what you pay" for camp, then you like payng for frivilous lawsuits and over-regulation. I AM saying that IFthese things were fixed, THEN the engines could be built for one forth of what we are currently paying. There is no technical barrier to doing so. Until these things are fixed, though, that is what we will be paying for. I am NOT saying that the opportunity exists for me or anyone else currently.
Tim
Tim and Wolfpack you have found the missing link.
How do we fix this problem?
Is it tort law reform? regulation reform?
but just imagine what would happen to the aviation economic industry if we could sell an engine ~ $5K. Should be worth a million new jobs. Why not sell it with a liability waiver that can't be sued?
ajay
How do we fix this problem?
Is it tort law reform? regulation reform?
but just imagine what would happen to the aviation economic industry if we could sell an engine ~ $5K. Should be worth a million new jobs. Why not sell it with a liability waiver that can't be sued?
ajay
automotive aviation revolution or hoax?
I still like this guy's claims;
LP1
http://www.woodward-aerospace.com/lp1.html
$200K build cost (similar to rv-10)
334 ktas on 14.5 gph
designed around the corvette v8 engine block
which makes it faster than a lot of these multi-million $$ turbine/jets at a fraction the cost and fuel burn:
Diamond D-Jet 315 ktas 70 gph
Epic LT 350 ktas 70 gph
Evolution Turbine 320 ktas 40 gph
Cessna Mustang 340 ktas 120 gph
Piper Meridian 260 ktas 45 gph
Propjet DLX 250 ktas 35 gph
TBM 850 320 ktas 65 gph
Can anyone explain how this is possible if even believable?
I still like this guy's claims;
LP1
http://www.woodward-aerospace.com/lp1.html
$200K build cost (similar to rv-10)
334 ktas on 14.5 gph
designed around the corvette v8 engine block
which makes it faster than a lot of these multi-million $$ turbine/jets at a fraction the cost and fuel burn:
Diamond D-Jet 315 ktas 70 gph
Epic LT 350 ktas 70 gph
Evolution Turbine 320 ktas 40 gph
Cessna Mustang 340 ktas 120 gph
Piper Meridian 260 ktas 45 gph
Propjet DLX 250 ktas 35 gph
TBM 850 320 ktas 65 gph
Can anyone explain how this is possible if even believable?
Such a thing does not exist, at least not in America.
Kyle Boatright
Well Known Member
This is a single point design - it is designed to do one thing well. Carry 4 people very fast. It is a composite, retractable gear airplane with about 75% of the wing area of an RV-6. It should have very low drag. The offset is that the stall speed will be extremely high, and an engine out situation would be ugly.
The RV series don't make huge compromises in any one area. They are all relatively fast, relatively roomy, relatively docile, etc.
dicel87
Well Known Member
The guys at UL Power sure seem to have "stepped up to the plate". They stayed with a largely traditional air-cooled aircraft engine layout but incorporated lots of modern features. I've been seeing more and more coverage of them in the last year or so and most of it seems positive.
I saw on their FB page that they are working a FWF installation of their 6 cylinder 200hp engine for an RV-8. Strictly fixed pitch right now though as they haven't worked through a CS solution.
But...as is the case with the Rotax, this is not an inexpensive proposition. I'm betting that the R&D costs, lawyer retainers, and insurance is what drives the UL price up just as it does for all the other major players.
Bob Kuykendall
Well Known Member
The thing that interests me is that all of the alternatives to Lycoming engines, be they automotive conversions, or purpose-built aircraft engines, come in at about the same price as a comparable Lycoming. These are new designs with significant startup, R&D, and tooling costs, and they're able to sell them for the same ballpark price as an existing Lycoming.
A Lycoming that now has next to zero startup, R&D, or tooling costs. That makes me wonder what the long term, ongoing cost would be to produce these alternative engines. I agree with someone earlier who said that it shouldn't be much more than $5K. I recall a few years ago someone saying that a crated Renesis engine from Mazda was on the order of $8K... But they were having a hard time buying one as Mazda had been tipped off that the buyer wanted it for an aircraft... No work done to adapt for aircraft use, of course, but there's a 200HP engine for under $10K right there.
A Lycoming that now has next to zero startup, R&D, or tooling costs. That makes me wonder what the long term, ongoing cost would be to produce these alternative engines. I agree with someone earlier who said that it shouldn't be much more than $5K. I recall a few years ago someone saying that a crated Renesis engine from Mazda was on the order of $8K... But they were having a hard time buying one as Mazda had been tipped off that the buyer wanted it for an aircraft... No work done to adapt for aircraft use, of course, but there's a 200HP engine for under $10K right there.
This is an interesting discussion. I still believe it would cost more than $5000.00 without tort reform or regulation. As someone stated earlier, look at a used price and it will tell you what something is worth. My RV4 used is worth maybe $50,000? Is that what the materials in it cost?
The 0-320 is have is more than the sum of its internal parts, crankshaft, pistons, etc. It also has a carb which isn't cheap, a PMag and Slick magneto, the exhaust system costs quite a bit, and the intake. The engines are not too complicated but start adding up the parts cost. Maybe it is because of the limited manufacturing, but have you ever tried to rebuild a Porshe flat six? Talk about expensive. Building a performance 350 Chevy with aftermarket heads would cost more than $5000.00 and that's starting with a used motor. My friend who has an ultralight rebuilds his Rotax two stroke every five hundred hours or so and that costs close to 5 thousand. (It's also blown up in the air 3 times).
I will take some regulation and AD's to keep me safe. But with experimentals you can put an outboard motor in it if you can find a way to make it work but no one has an engine for $5000.00 or less. Heck, a 10 hp outboard costs almost $3000.00.
The 0-320 is have is more than the sum of its internal parts, crankshaft, pistons, etc. It also has a carb which isn't cheap, a PMag and Slick magneto, the exhaust system costs quite a bit, and the intake. The engines are not too complicated but start adding up the parts cost. Maybe it is because of the limited manufacturing, but have you ever tried to rebuild a Porshe flat six? Talk about expensive. Building a performance 350 Chevy with aftermarket heads would cost more than $5000.00 and that's starting with a used motor. My friend who has an ultralight rebuilds his Rotax two stroke every five hundred hours or so and that costs close to 5 thousand. (It's also blown up in the air 3 times).
I will take some regulation and AD's to keep me safe. But with experimentals you can put an outboard motor in it if you can find a way to make it work but no one has an engine for $5000.00 or less. Heck, a 10 hp outboard costs almost $3000.00.
johngoodman
Well Known Member
I'll admit that a performance engine would cost more, but you can certainly start with a new one...
http://www.summitracing.com/parts/NAL-89017548/
John
wolfpack21643
Member
I wouldnt call a 100hp (Rotax 912) or 160 hp Lycoming high performance as far as horse power and torque goes. When you talk about $10,000 car engines your talking about alot more HP then what is used in the avg RV world.
I have a friend who built a Factory Five kit car with a 500 HP Chevy crete motor. I think he paid around $14,000 for it ready to run with fuel injection and all. He has 40,000 miles on his car and it hasnt missed a beat yet. I can only guess what a fuel injected 500 HP Lycoming would cost
I think it all boils down to a combo of 4 things:
1) Number produced (R&D / Tooling cost)
2) Lawyers
3) Higher labor cost(I was into skateboarding in the 80's and a high end skateboard was $100 complete in 1987. I just bought my daughter a high end one last week that was $80 complete. That means that your getting better / newer technology at a negitive inflation rate which is amazing) But then again skateboards are made in China along with most other stuff and if airplane engines are built in the US or Europe then the labor cost have to be alot higher.
4) Govt. Regulation (sometimes good, but when was the last time the Govt turned anything into an easier / cheaper thing)
I think that pretty much sums up the why part.
I have a friend who built a Factory Five kit car with a 500 HP Chevy crete motor. I think he paid around $14,000 for it ready to run with fuel injection and all. He has 40,000 miles on his car and it hasnt missed a beat yet. I can only guess what a fuel injected 500 HP Lycoming would cost
I think it all boils down to a combo of 4 things:
1) Number produced (R&D / Tooling cost)
2) Lawyers
3) Higher labor cost(I was into skateboarding in the 80's and a high end skateboard was $100 complete in 1987. I just bought my daughter a high end one last week that was $80 complete. That means that your getting better / newer technology at a negitive inflation rate which is amazing
) But then again skateboards are made in China along with most other stuff and if airplane engines are built in the US or Europe then the labor cost have to be alot higher.4) Govt. Regulation (sometimes good, but when was the last time the Govt turned anything into an easier / cheaper thing)
I think that pretty much sums up the why part.
True, but try to fit that in your RV, and ask why so few are put in RV10's or any other aircraft. Remember, we are talking about providing an aircraft engine for $5000.00. If you read the entire thread there is plenty of discussion of why it can't be done from a startup for so little.
