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Radial powered RV-8R V2.0

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OK Dan, I'll bite :D. It's not either of Liston's books "Aircraft Engine Design" or "Powerplants for Aircraft". So what's the title and the author?

Terry, I don't know. It was a long time ago. As you probably know, the Air University Library is on Maxwell AFB, and civilian access requires an active duty sponsor. I wasn't sure if I could borrow any books, so I was was simply copying relevant pages with the library copying machine.
 
What's F1?

Fundamental frequency, first natural frequency, lowest vibratory mode. Different users may notate it otherwise, but here's the picture.

Aircraft propeller mass moment of inertia is almost always much higher than powerplant mass moment of inertia, so imagine a simple two element system as a large flywheel connected to a smaller flywheel with a shaft, hanging free in space....two intertias connected by a stiffness.

Using your giant magical hands, hold the big wheel stationary and turn the small wheel a few degrees, in a manner which twists the shaft, now a torsional spring. Release both wheels at the same time. The wheels will begin to oscillate in opposition. The angular displacement of the large inertia will be less than the angular displacement of the small inertia, but the period (rate, cycles per second, hertz) will be identical. The period at which they oscillate is the natural frequency (F1) of the simple two element system, a function of the inertias and the connecting spring rate. Change an inertia or the spring rate to change the frequency.

A real system can (and does) have multiple inertias and connecting stiffnesses. The number of available natural frequencies (F1, F2, Fx, etc) and vibratory modes is always total inertias less one. I've attached some examples below. Note the "mode shapes", a name which seems to stem from the 2D drawings depicting them in old texts (example below). At F2 and higher, the various inertias take up different rotation directions in relation to other inertias.

Note that natural frequencies are passive. They are the frequency at which the mode oscillates if excited, which is the key concept in application. When excited at a forcing frequency other than the system natural frequency, nothing much happens. When excited at the same frequency, the system resonates; the amplitude of the oscillation grows, and without damping, can theoretically reach infinity. It's theoretical because (1) there is always some damping, and (2) no connecting stiffness is infinitely strong...
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Bit 'o thread drift here, and I'm guilty as any. Torsional vibration is a subject more homebuilders should contemplate, in particular those who want to fly alternative engines. However, it is a big, complicated subject, and this thread is about Brian's RV-8...so let's just follow his progress with the new engine.

Hopefully Verner understands the torsional stuff!
 
Bit 'o thread drift here, and I'm guilty as any. Torsional vibration is a subject more homebuilders should contemplate, in particular those who want to fly alternative engines. However, it is a big, complicated subject, and this thread is about Brian's RV-8...so let's just follow his progress with the new engine.

Hopefully Verner understands the torsional stuff!

LOL, I figured that I would just sit back and let you guys hash this one out. Anyways......I posted some more pictures on the FB page yesterday. Progress is coming along smoothly. To those of you who don't have a FB account. Sorry, but I don't use any third party pages to store photos just for VAF. I might be wrong, but you might not need an a FB account in order to see the page.
 
Fundamental frequency, first natural frequency, lowest vibratory mode. Different users may notate it otherwise, but here's the picture...
OK, OK, back to the thread but, Dan, this is really interesting. Thanks for posting.
 
Brian, it's a new day...photo hosting right here on the VAF servers. Just click the little bitty paperclip icon above the "Reply To Thread" screen and post photos, easy as pie.
 
latest update

The Verner 9S is proving to be a strong engine. The one thing that I am changing about it is the fuel delivery system (carb). I am adapting an Airflow Performance FM-150 to the engine. In order to do this I designed an adaptor that fits the unit to the engine and also houses the flow divider and fuel injectors. Along with an SDS duel fuel pumps setup I think this will really make the engine a winner.
 
Here are some pictures of the adaptor used to mate the FM-150 to the Verner that I designed and had machined.

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I'm really glad to hear you are doing this!

I have been thinking about building a Hatz, so I have looked into both motors. Special attention to service history and customer service. The only knock I have on the Verner is that it is an all-electric system. Lots are nowadays, and with proper attention and integration, it can be done 'safely'.

Still, with something like a Hatz, I would really prefer the simplicity of a magneto and a mechanical fuel pump. switching to the FM-150 seems like a good step. Are there any issues of physical orientation of the flow divider and/or length of the injector lines?
 
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Today I put the GT prop back on and did a test fit with the cowling to verify prop clearance. I also started installing the ignition packs with their cooling boxes.

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I'm really glad to hear you are doing this!

I have been thinking about building a Hatz, so I have looked into both motors. Special attention to service history and customer service. The only knock I have on the Verner is that it is an all-electric system. Lots are nowadays, and with proper attention and integration, it can be done 'safely'.

Still, with something like a Hatz, I would really prefer the simplicity of a magneto and a mechanical fuel pump. switching to the FM-150 seems like a good step. Are there any issues of physical orientation of the flow divider and/or length of the injector lines?

I hear ya with the all electric systems. Just have to bake that into the cake when designing the electrical system. The Adaptor to the FM-150 houses the injectors, lines, and distribution block (see earlier post). This allows the FM-150 to be oriented in any direction except for down.
 
I hear ya with the all electric systems. Just have to bake that into the cake when designing the electrical system. The Adaptor to the FM-150 houses the injectors, lines, and distribution block (see earlier post). This allows the FM-150 to be oriented in any direction except for down.

I hadn't caught the detail that you are using the adapter to do throttle body injection with the FM-150. I guess that is a lot simpler than trying to add port injection.

And with carbon-fiber induction tubes, you can't exactly weld on injector bosses into the induction tubes. I was wondering about even fuel delivery to port injectors with 3' of head difference between the top and bottom also.
 
We have a customer fitting our EFI to the same engine for a Corsair replica. He's done a nice job mating injector bosses into the induction tubes but a ton of work.
 
We have a customer fitting our EFI to the same engine for a Corsair replica. He's done a nice job mating injector bosses into the induction tubes but a ton of work.
That will be really cool - EFI in a radial - there can't be too many of those!
 
We have a customer fitting our EFI to the same engine for a Corsair replica. He's done a nice job mating injector bosses into the induction tubes but a ton of work.

I bet that is a ton of work, and I think it will make for a great engine. for this installation I took a page out of Elon Musk's book. The best part is no part. Keep it simple.
 
Twin row radials/ Devil Dog B25

I get to fly behind 2 ea Wright R-2600’s regularly. Magnificent noise from those babies!! Cruise sounds like cannons beside your head; descending into the pattern is more like .50cal going off beside your window... My thanks to Zulu Lightspeed headsets. Figure 65-70GPH in cruise on each side.:eek:

Wright Engines figured out the twin row problem with their R2600 before Pratt got into their problems.

Yes - the the R2600 still has a zone the operator needs to stay out of (continuous RPM). 44”/2600RPM on takeoff (1700HP); 30”/2000RPM in climb; 27”/1800 in cruise. Our B25, The Devil Dog, shows ~190MPH in cruise - but ours does not have a FWD turret gun, so The Dog is a bit faster than other more exterior equipped B25’s. VNE is 340MPH, but we never get close to that - maybe 240 in some of the airshow antics - maybe 3.5G in some of the turns with a healthy dive helping to get to that speed. Let’s call her about 22000lbs of fun - 19000lbs empty empty weight.

I can’t recall which paper mentioned it, but Wright sold (or transferred) their twin row setup (counter weights/front-rear clocking/crankshaft design etc) to Pratt & Whitney for “the duration”. I can tell you the R2600 has spherical weight inside the base of each prop blade - reading this tells me why! I can say that Pratt techs blew up a lot of engines before Wright stepped in - probably with some Government prodding (think $$$). The R2800 was heralded as the best engine in WW2.

I’d like to hear how Wright set up the R-3350 - now there was great gobs of HP coming out of that shaft!!
 
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Here are some pictures of the adaptor used to mate the FM-150 to the Verner that I designed and had machined.

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Brian, you've probably considered this, and if so, just a footnote...an EFI or carb has little or no fuel flow prior to engine rotation. However, constant flow injection does deliver without rotation, and if allowed in excess, has the potential for liquid lock in this horizontal configuration. For the same reason, an airbox drain may be a good idea, much like a sniffle drain on a Lycoming.
 
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Brian ( flyboykelly ) so glad to see some pictures of your project here on VAF . Yours was the inspiration for mine . Sorry to hear that the Rotec didn’t live up to your expectations, hopefully it will be adequate for mine

Following in your footsteps
 

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Brian, you've probably considered this, and if so, just a footnote...an EFI or carb has little or no fuel flow prior to engine rotation. However, constant flow injection does deliver without rotation, and if allowed in excess, has the potential for liquid lock in this horizontal configuration. For the same reason, an airbox drain may be a good idea, much like a sniffle drain on a Lycoming.

Dan,

Yes, I've already considered this and it will have to be addressed in the starting procedures. The injectors spray directly into a fan housing which leads directly to the intake pipes. So there is no place for a sniffle valve. Radial engines are started with the ignition off and after so many rotations (in order to verify no hydraulic lock) the ignition is added. during this time I'll most likely start in idle cut off and then introduce fuel with the mixture control while the engine is rotating, then hit the ignition and we are off to the races.
 
Brian ( flyboykelly ) so glad to see some pictures of your project here on VAF . Yours was the inspiration for mine . Sorry to hear that the Rotec didn’t live up to your expectations, hopefully it will be adequate for mine

Following in your footsteps

Great to see your progress as well! I didn't have any issues with my Rotec. I was mainly looking for some more HP and direct drive. Looking good!
 
Dan,

Yes, I've already considered this and it will have to be addressed in the starting procedures. The injectors spray directly into a fan housing which leads directly to the intake pipes. So there is no place for a sniffle valve.

I was thinking about the airbox, unless of course it is a downdraft feed to the throttle body. Even then, you'll need to seal the junction between duct and throttle. When tail down, on the ground, don't want fuel dripping in the engine compartment.
 
I was thinking about the airbox, unless of course it is a downdraft feed to the throttle body. Even then, you'll need to seal the junction between duct and throttle. When tail down, on the ground, don't want fuel dripping in the engine compartment.

Yes, this installation is a downdraft feed.
 
HP / Torque Debate: Watch Out! :)

Technically, no. Again, torque is only a force. Force x distance ("how far you'll move it") = work. Common terms would be Joules or ft-lbsf.

Let's not get too far afield here. Subject is a lovely radial RV-8. I was merely noting more torque at lower RPM is not in itself significant. Potentially, in some applications the lower RPM could allow a larger prop disk at the same tip speed (72"@2700 is the same as 81"@2400), and some advantage might be found. However, that route is limited by the RV-8's leg length.

Dan: Your expert comments reminded me of a P&W Aero Engineer friend (multiple patents for work on F-100 development) who got in trouble (at work) by simply lending his expertise in a similar way, to an article that appeared in a flying magazine in the 80's. You might remember a guy back then who was putting Olds/Buick small block V'8's in a/c, and he had some crazy ideas about torque vs. hp; so a writer of an article debating that point asked my friend to check out his "math", AND also used his name and assoc. as a P&W aero engineer in the article. Well the article printed and the nut case V-8 engine developer was so mad he wrote multiple letters to the President of P&W asking "how could you ever hire such a stupid engineer...", etc., etc.! The President then called up friend and asked him to please not enter into any more debates, out of fear it might hurt business, etc. :)

Doug
 
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I recall reading about the Radial RV8. It is a little slower than a Lyc powered RV8. Rotec has a checkered reputation. Research it. Support might be less than stellar. These engines share nothing in common with P&W, Wright, Jacob, Warner. Don't assume it's round it will have legendary reliability these great legacy engines had.
 
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I recall reading about the Radial RV8. It is a little slower than a Lyc powered RV8. Rotec has a checkered reputation. Research it. Support might be less than stellar. These engines share nothing in common with P&W, Wright, Jacob, Warner. Don't assume it's round it will have legendary reliability these great legacy engines had.

Hence one of the reasons for the change over to the Verner. I went into this eyes wide open, as do most people who dive into the alternative engine world. This is experimenting, which for people like me is half the fun.
 
Hence one of the reasons for the change over to the Verner. I went into this eyes wide open, as do most people who dive into the alternative engine world. This is experimenting, which for people like me is half the fun.
I have to strongly disagree following alternative engines (more automotive) for over 30 years, with an open mind. What I saw was many people jumping in naively, uninformed and with unrealistic explications. After expending more effort, time and money ended up disappointed. I am NOT talking about you, but I could write a long list of examples. I'm sure you know. Up to you.

Verner is interesting. Czech Republic built engine, Scarlett 9S at 158HP is their largest motor and weighs 240 lbs dry. Fixed pitch prop only? "Looks good" on paper. The only thing I know about them is in a few YouTube Videos. I'm sure you saw this one. https://www.youtube.com/watch?v=s-BOd4QxDCQ

I hope it works out for you. All the best and have fun. Please do chronical your radial engine journey and share it.

My idea of an engine conversion is to convert $28,000 into a Lycoming and have fun flying. Actually my 180HP O360 cost me $12K. Low time engine core $4K and $8K on DIY rebuild, including sending out crank, rods, case, heads, Carb. Does not include EI.
 
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I have to strongly disagree following alternative engines (more automotive) for over 30 years, with an open mind. And what I saw was many people jumping in naively, uninformed and with unrealistic explications. I won't write a book on the examples, but I am sure you know what I am talking about.

Verner is interesting. Czech Republic built engine, Scarlett 9S at 158HP is their largest motor and weighs 240 lbs dry. Fixed pitch prop only? "Looks good" on paper. The only thing I know about them is in a few YouTube Videos. I am sure you saw this one. https://www.youtube.com/watch?v=s-BOd4QxDCQ

I hope it works out for you. All the best and have fun. (PS please do chronical your radial engine journey and share it.)

I'm not going to get in to a semantic argument with you on who knows what about alternative engines. The only thing that I will add with the Verner is that it is only fixed pitched when paired with their previously used EFI. With their carb or with my FM-150 mod, you can use an electric constant speed prop. I am keeping everyone posted on my progress with my radial conversions Facebook page. As to the edit to your post with regards to the cost of a standard flat engine. You are missing the entire point of the radial engine conversion. It has nothing to do with cost, performance, reliability, and everything to do with just doing something different and being unique.
 
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I'm not going to get in to a semantic argument with you on who knows what about alternative engines. The only thing that I will add with the Verner is that it is only fixed pitched when paired with their previously used EFI. With their carb or with my FM-150 mod, you can use an electric constant speed prop. I am keeping everyone posted on my progress with my radial conversions Facebook page. As to the edit to your post with regards to the cost of a standard flat engine. You are missing the entire point of the radial engine conversion. It has nothing to do with cost, performance, reliability, and everything to do with just doing something different and being unique.

https://www.youtube.com/watch?v=lj60OAh7O5U

Ha ha. I get it. Don't be defensive. I am on your side. I love me some round engines. I believe you are well researched and in no way am I questioning your motives or goals. I get it. I wish you all the best. However when I saw Rotec red flags went up. Personally it's not my cup of tea, I am a bolt on a Lyc go fly guy. I experiment with my choice of Scotch and Cigars. Ha ha.

My comment was not directed at you or Verner S9 radial specifically. However you made a broad statement that alternative engine users are all very aware and realistic. I can't tell you how many times over 35 years people selling alternative engines promising the world and builders who buy into the dream end up disappointed. There are exceptions, but they are the minority.

Honest alternative engine sellers, buyers, users often say hard to beat a Lycoming O320, bang for the bucks. However I get it people want to experiment and try new things. From that sometimes there are good results. However it takes special drive, determination, skill, effort to make it work. On the other hand I have seen way more people with unreasonable expectations.

I have an open mind about Verner Motor Czech aircraft engines. My blanket advice to others about new kit planes or new alternative engines is find THREE PEOPLE who are actually flying that KIT or ENGINE and talk directly to them. I would find out how many are flying and how many hours each has and est total fleet hours. How much testing did factory do? These engines are only about 4 yrs old. It is reasonable to expect there may be some growing pains. Lycoming's have been flying in some form since the O145 in the late 1930's. The Lyc started as a solid design but not perfect and has benefited from continuous improvements over 80 years.

I truly look forward to seeing your project progress and hope you share it. :)
 
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Any way I can swing by and take a look? I am 2 blocks away awaiting my -9 fuse. We have spoken before during parades but life gets in the way and I don't get out much. Feel free to private message...
 
Haha

“…The Lyc started as a solid design but not perfect and has benefited from continuous improvements over 80 years…”

That is hilarious!

Of course the price has definitely seen continuous increase over the last 80 years…
 
“…The Lyc started as a solid design but not perfect and has benefited from continuous improvements over 80 years…”

That is hilarious!

Of course the price has definitely seen contiguous increase over the last 80 years…
Are you kidding... You are Hilarious!!! :D The price of LYC has GONE DOWN (vs inflation). Why? Lycoming (Textron), Superior, ECI, Titan.... We are so lucky dripping with Lycs and Lyc clones using PMA parts. Competition = lower prices. These are Lyc (Textron) prices TODAY (just after the recent price increase due to inflation affecting everything). From Van's web store:

Experimental O-320 160HP EA XO-320-D2G RT $28700.00
Experimental O-360 180HP EA XO-360-A1A RT $29400.00

Go pre "panorama" prices (sp intentional :D ) prices were $3K less. At Oshkosh I talked to the Superior guy. He had a brand new bright shinny O-360 (180HP) engine for $28,000 today. Prices have gone up for EVERYTHING, not just flying. Price a Gal 100LL of late? Manufactures are having a hard time getting materials etc.

Now what do you think that 159HP Vernier S9 cyl piston engine cost? The price I found for a Verner S9 (2018 price) was $31,000. I am sure it is more 2021. Let's not forget shipping from East Europe. Lyc has 2000 hrs recommended TBO the Verner is 1000 hr TBO. I recall the Verner S9 crank is solid crank, no hydraulic CS prop.

BTW ever price a Rotax? A new 915Si (140hp) costs $40,350. :eek: That is way more than a Lycoming. Yet you are going to whine about Lyc prices? $29K for a Lycoming is a bargain.

RESALE... A nice RV with a low time Lyc and well stuffed glass panel are now selling for $120K routinely. If you buy a Lyc you will get your money out of it. Alternative engine powered planes tend to sell for less. I don't know about a Verner S9 since it is so new. But Lycs are desirable.

My RV4 had a O320 150HP with Hartzell CS prop and at 8,000 ft cruised 190MPH and SL top speed 208 MPH. I could go 22 square and scoot along at 6 GPH... Really a great engine. So a O320 (150-160hp) is less money and will still make any 2-Plc RV scoot along. You have to pay to fly. You know aerodynamics? How to planes fly, right. Lift? NO... Money. Ha ha.

What is your POINT?
https://www.youtube.com/watch?v=lj60OAh7O5U

TALE OF CHEAP LYC
I have $12,000 in my fresh OH Lyc O-360-A1A *(180HP). How? bought used 0-360 with 600hrs on first overhaul from new. Paid less than $3,000. I tore it down with AI friends help. Shipped case, crank, rods and carbonator off for OH. The heads, pistons, rings, valves, seats were great and did an inspection. Put it back together. Have less than $8000 in parts and labor, plus $3000 for electronic ignition and small ND alternator. Grand total about $14K. You can't touch that value.

You are hilarious. :D
 
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The current price for the Verner is almost $26,000. Includes everything except for the oil tank. Also you can run an electric constant speed prop. The GT one that I used on the Rotec paired with a flybox governor works great.
 
Confused

I try not to speak up in these types of post wars but it is confusing.

Don't recall the OP stating his approach was best/cheapest to install/cheapest to maintain/most efficient/whatever.

The owner wants his 8 to be a radial. He has the means and skills. Beauty is a relative thing, of course. I think the pix are darn near airplane p0rn. Would love to have something that original. Let the man build what he wants in peace.

@flyboykelly. I'm building down the road in Orlando. Would love to get a real look next time we're grabbing lunch at the Creek.
 
I try not to speak up in these types of post wars but it is confusing.

Don't recall the OP stating his approach was best/cheapest to install/cheapest to maintain/most efficient/whatever.

The owner wants his 8 to be a radial. He has the means and skills. Beauty is a relative thing, of course. I think the pix are darn near airplane p0rn. Would love to have something that original. Let the man build what he wants in peace.

@flyboykelly. I'm building down the road in Orlando. Would love to get a real look next time we're grabbing lunch at the Creek.
There is no war? We established long ago this is not about "best/cheapest to install/cheapest to maintain/most efficient/whatever." We got it.
 
I try not to speak up in these types of post wars but it is confusing.

Don't recall the OP stating his approach was best/cheapest to install/cheapest to maintain/most efficient/whatever.

The owner wants his 8 to be a radial. He has the means and skills. Beauty is a relative thing, of course. I think the pix are darn near airplane p0rn. Would love to have something that original. Let the man build what he wants in peace.

@flyboykelly. I'm building down the road in Orlando. Would love to get a real look next time we're grabbing lunch at the Creek.

Sounds good to me! PM me the next time you're in town. As to the thread, These things are the reason that I stopped posting on the internet. The original points gets lost in other peoples desire to be heard for a variety of reasons. Again I put up pictures on my FB page when I make progress. If anyone wants to follow then please go here:

www.facebook.com/radialconversions

This thread is now closed.
 
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