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Sportbike Engines?

Madredr1

Member
PLEASE PLEASE PLEASE forgive the ignorance of this post, but I'm just curious if this have ever been brought up.

Over the years I have been a Yamaha fanatic, and I know some of the R1 engines push out 200 horse at the crank. With reduction drives out there, is it possible to mate these high powered sportbike engines to a reduction drive for flying? I know the transmission is probably an issue, but I think snowmobiles use the same engines without the gearbox of a sportbike.

Is this silly to even consider?

Sorry, had to ask. I've just been thinking about various engines out there, and this one popped into my head.
 
Many have tried

And many have failed. Auto and motorcycle conversions ultimately take massive amounts of development time and rarely pan out for the long run. Some missteps in such development have cost people their lives.

A quote which has been attributed to Van holds that, "The best engine conversion you can accomplish is to take about $25,000 and convert it into a new Lycoming."

Word
 
Couldn't agree more

Having run auto conversions in airplanes in the past I can absolutely attest that the best way to constant tinkering and re-engineering (even on an established conversion) is to put a non airplane engine in it.

I struggled for years with valve guide falling out of my cylinder heads.. turns out the "converter" had no clue what he was doing and the issue eventually caught up with him. He was using cylinder heads "rebuilt" by a local shop that quite honestly were only fit for scrap.

Of course lots of finger pointing, guy even claimed that because I was running two ignitions at the same time it was causing the valve guides to fall out.. Nice one!

I re-egineered the problem and the guy eventually stopped doing engine conversions... about $1500 total to fix and some very scary moments as the engie repeatedly ate valve guides.

Frank
 
A quote which has been attributed to Van holds that, "The best engine conversion you can accomplish is to take about $25,000 and convert it into a new Lycoming."

Word

I saw that quote on their website, and it makes perfect sense - stick with what works. But I guess the alternative engine thing has caught my attention because of the GA pilots around here discuss the increasing cost of 100LL, and some even speak of it eventually going away forever.

The deltahawk definitely had my attention, until I saw the price tag...

Oh well, was just curious....
 
...The deltahawk definitely had my attention, until I saw the price tag...

I would suggest not expecting to pay much less, when all is said and done, for an equivalent auto or motorcycle conversion powerplant. I guess it depends on how you value your time and energy. It also depends on how you value the opportunity cost of beautiful flying days spent tinkering, developing, troubleshooting, removing, and reinstalling.

Thanks, Bob K.
 
From the stand point of technical understanding you have a legitimate question. While the full answer would be volumes, it will be shorter.

!. engines are designed to fit a specific purpose. Cost, Life, weight, fuel consumption, load factor, and reliability. What is being driven and the output rpm and working range, response, are 2nd level but still extremely influential issues to the design.

2. For an aircraft the load factor is quite high. Need for average mission weight, (engine+fuel) is quite important. Life, TBO, relates to total cost of operation.

Even an F1 race car only has a load factor of about 50-80% (monza=83%) WOT for a course and wot time is limited to a 23.5 second burst (Spa straight). An airplane is typically wot from takeoff to descent. Short hops at partial throttle not withstanding.

OK, so what happens? Well, the engine is designed to balance the parameters and the plane has a high emphasis on that mission weight thing. Fuel consumption is big. Initial weight is big.

So, the aero engine is designed around the rpm (Primarily), with prop tip speeds being an issue. Then the bore stroke is limited for piston speeds. This keeps overall friction low and SFC up. Size and temps of components are such to keep operating temps in line, factoring that WOT thing.

Contrast, the motorcycle engine is:

light weight- check
powerful - check
durable - well, maybe 20 hours? (ok, maybe 200)
efficient - not likely, so fuel burn would be an issue.
reliable - maybe, for the 20 hrs and lots of PM.
will need reduction for prop speed.

Auto engines are made to be cheap, and the load factor for a 300 hp street car is probably, hmmm - 7-10%? WOT for, 15-20 seconds, (shifting not counted) and weight, and reliability for flight, . . . . well, it would take a lot of work to get it to work, then, you become developer of and engine designed for a different purpose.

For a fun little, low performance, plane to kick around short distances, and 500 hrs TBO, the auto engines can be just fine. Or high performance for a shorter time.

Reduction drives are a whole, other story, adds weight, must be highly engineered to handle complex loadings. The highly engineered and developed part usually bites low capital investment approach hard. They can work, Rotax shows that. P-51 too. Also affects the engine design , like RPM range.

Better ? too much?
 
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A future you from a parallel universe in which you decided to go down that path is screaming DONT DO IT!
 
The bike engine conversions such as the Harley and BMW are pretty much limited to around 65hp for longevity. Quite a number are flying the BMW ones in Europe successfully.

As far as auto conversions go, there are some which have worked out acceptably well or even very well but the majority have not over the longer term (say over 5 years+). This is generally not so much to do with the engines themselves which are usually very robust and extremely well tested by the OEMs but rather have been let down by things like poor cooling system design and more (most) frequently poorly designed and tested PSRUs. Duty cycle has not proven to be much of an issue in most cases at the typically derated power levels auto conversions are run at although lay people love to speculate about this. We see almost no serious failures on modern auto engine which are completely stock internally and run within reasonable temperature, ignition timing and AFR limits. The OEMs test most designs a minimum of 200 hours at full power, some OEMs up to 1600 hours at WOT torque peak to power peak rpm which is far in excess of what is required for aviation certification actually.

Overall better reliability has been achieved mainly through a lot of hard/ painful lessons by running and breaking things but we do know a lot more now than even a few years ago. Lots of bad experiences were simply due to ignorance of things mechanical by many people. Since this is a pretty complex field, it has not been well served by a lack of basic engineering- many conversions are little more than thrown together and if you get something basic but important wrong, things can go very badly.

Today we have a pretty good idea how to efficiently cool the engines and provide fuel and spark reliably. We also have a bit more information on torsional vibration issues as related to PSRUs which until recently was mostly dismissed or ignored by most people. TV is a big deal potentially, especially with 4 and 6 cylinder conversions.

Most successful conversions have been done by engineers and gearheads. There have been a few which were done by relatively lay people that have worked out well, but only by luck really. With this being said, worldwide, there are thousands of auto conversions flying and working very well, conversely, thousands more have not worked out well and have been abandoned. The slow learning curve is primarily from the usual, one off nature of conversions. Lessons learned were often not communicated to others who would simply make the same mistakes over and over. Internet conversion forums have helped reverse that trend somewhat more recently though a sharing of experiences.

Done properly, auto conversions can come out a lot less expensive to acquire and operate over time. Done improperly, they will simply be a sponge on your time and finances.

I've been flying an auto engine for 10 years now and helping others for almost 20. I've heard of most of the successes and failures over that time. After all this time, I can't think of a single complete FF auto conversion which has been professionally engineered and validated in the conventional sense, which is available commercially today. There are some however which have simply stood the test of time over many years and have proven reliable despite a lack of applied engineering and reliable flight time in the end is really the most important measuring stick of all.

Today, we can put together a reliable and fairly weight comparable 60-200hp auto conversion using components from commercial sources but this is still a lot of work and for most people, especially those without a deep engineering and /or mechanical background, is simply ill-advised and not worth it. For the majority of builders, Van's advice is still the best- fit the Lycoming that your budget can afford.
 
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Oh, I'm not deciding to go down that path, I was just curious - I see the subaru conversion, corvette powered RV10s, and just thought "why not a Sportbike Engine?"

I am pretty nervous about the future of 100LL, which is why the alternative engine route caught my attention....
 
Keep in mind that most of the piston aircraft engine fleet runs just fine on auto fuel. Yes, there are some system level issues to overcome due to the trash they add to the fuel, but that hurdle is a whole lot easier than design and integration of a new engine.
 
Oh, I'm not deciding to go down that path, I was just curious - I see the subaru conversion, corvette powered RV10s, and just thought "why not a Sportbike Engine?"

I am pretty nervous about the future of 100LL, which is why the alternative engine route caught my attention....

They won't orphan tens of thousands of aircraft with no alternate unleaded aviation fuel. At least 3 companies are working towards solutions. The first one who takes the plunge to get production and distribution rolling with the blessings of the FAA and the major existing avgas suppliers will probably be the winners. The production and distribution are pretty big things to handle for a startup in my view. Most of the Lycoming engines in RVs can operate just fine on 91 unleaded mogas already.
 
Fact...there's a guy here in Alabama with a CBR Honda on a Drifter-class two place. Has a bunch of hours on it, like maybe 1000. Drives the airframe-mounted propshaft with the standard bike chain, using the standard transmission. And yes, he can shift in flight.

Gotta be careful about what you claim won't work ;)
 
Fact...there's a guy here in Alabama with a CBR Honda on a Drifter-class two place. Has a bunch of hours on it, like maybe 1000. Drives the airframe-mounted propshaft with the standard bike chain, using the standard transmission. And yes, he can shift in flight.

Gotta be careful about what you claim won't work ;)

Cool!

Well we engine and bike guys know that a Japanese sport bike engine is not going to blow up or wear out in 20 hours running at 2/3rds redline...

As you say, many people simply speculate without facts or knowledge. I've seen some pretty simple conversions work and work well for a long time and others which never worked well, even after years of development. It's all in the details but the basic modern bike or auto engine is usually very well engineered and very reliable, even under severe use.
 
Bike engines are an interesting idea, but probably not workable due to the high duty cycle already mentioned. I'd love to see the inline-6 out of my (ok, not MY, but another) K1600GT in an airplane. 160Hp and > 100 ft-lb, very compact and oh so smooth... but you'd need a PSRU and go look at how long it took Rotax to make those reliable and lightweight...
Even an F1 race car only has a load factor of about 50-60% WOT for a course and wot time is limited to a 15-20 second burst. An airplane is typically wot from takeoff to descent. Short hops at partial throttle not withstanding.
So, Spa is the next race on the calendar, and IIRC, its >70% WOT there and if you don't lift through Eau Rouge, its about 40 sec WOT up the Kemmel (its "easier" to stay WOT through eau rouge in the V8 era as opposed to the 1000Hp V10s, as if anything about that corner was easy). Back before the detuned engines, when the V10s hit 20,000 RPM, Spa was always good for some on-track engine destruction. Ka-Blammo!

TODR
 
Do it!

Who wouldn't want to witness an R-1 powered, gear driven RV launch turning 13,000 rpm's?
 
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The sound of the engine with the new cross plane crank is amazing. It doesn't sound like any inline 4 ever made. It actually sounds more like a v-twin engine. I would love to hear one flying overhead!

799px-Crossplane.png


http://youtu.be/z5Qdg_QRAIA?t=1m50s
 
Who wouldn't want to witness an R-1 powered, gear driven RV launch turning 13,000 rpm's.

I guess that kind of interested me as well. In my younger years I bought a 2002 r1 brand new, love the sound of the engine and deep tone of the 998cc engine at high rpms. Used to give me goose bumps.

Oh well, thanks for all the discussion guys, it was interesting to hear thoughts on the matter. I know the engines can take a beating on land, but didnt think about the different experience the engine would have in the air.

I'm no engineer, I have just worked on quite a few R1s over the years and just wondered why I hadn't seen more cycle engines in experimentals - now I know!
 
weak link

It's not the engine - it's the PSRU. Start there, and then look for an engine that will provide the power/torque required.

Seems that Geared Drives had broken the code in terms of vibration by simply adding the clutch springs back into the drive system. The accident stopped all that R&D....as far as I know, the engine/drive system was not at fault?

Carry on!
Mark
 
It's not the engine - it's the PSRU...

Sort of... When stuff "breaks", it’s often the TV issue. And TV is an issue for the entire system from one end of the crank to spinner. Change the mass of one part in the system and you alter the TV signature of the whole thing. So finding a robust gearbox or a coupler that "fixes" the issue on one combination may be a disaster on another. Without instrumentation on each combination, it's little more than blind luck when something works.

TV is a very complex issue for aircraft because we don't have the luxury of a heavy drivetrain rolling along rubber tires to dampen the whole mess out. We often have a large metal tuning fork (the prop) singing away undampened along with the crankshaft constantly winding up and springing back – find the right condition where those two elements line up and you get a rapid force amplification that can snap a crank like a dry twig. Throw a reduction gearbox in there and you have just compounded your problem exponentially.

There is a very good dissertation about TV and how it plagued the early BD-5 development. Also, the now ubiquitous P&W R2800 engine almost didn't make it out of development because of seemingly insurmountable TV issues.
 
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Remember the "Hog Air"???

Yeah, but I really liked the one that went the other way. :eek:

radial_mc_zps11c3a875.jpg
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I wonder how far it goes between oil stops?

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
It's not the engine - it's the PSRU. Start there, and then look for an engine that will provide the power/torque required.

Seems that Geared Drives had broken the code in terms of vibration by simply adding the clutch springs back into the drive system. The accident stopped all that R&D....as far as I know, the engine/drive system was not at fault?

Carry on!
Mark

The Geared Drives design is under new ownership and they are working on some fixes to retain oil seals properly and beef up the clutch mechanism having had failures on both with rather serious results. The basic gearbox design seems pretty sound to date on V8 applications but once again, change one thing and the track record goes out the window. The 200Z box as applied to a six cylinder Subaru had a possible TV failure in very short order for one early customer. The clutch springs actually do very little in this system.

Four and 8 cylinder TV signatures and problems are vastly different. The V8 is quite benign by comparison because there are no torque reversals and generally, the common gearbox designs have F1 well below typical idle speeds. The well regarded Geschwender chain drives usually had the death rattle (probable F1) around 300-400 rpm so they would hit this only on startup and shutdown. On the V8 apps, the Geared Drive clutch effectively gets rid of F1 problems by decoupling the engine and prop, on 4 and 6 cylinder engines it may do nothing. No engineering, testing or calculation was used in this design to my knowledge so only a few thousand collective flight hours on a certain combination will validate the design

Changing propeller and flywheel inertias can result in pretty major TV changes. While the gearbox manufacturer can probably supply the recommended flywheel, it is harder to confine users to a certain range of propeller inertias because of different airframe requirements but this is really what should be done as Rotax does. Ideally, the PSRU maker should perform a complete TV and prop vibration study for each approved combination. These days, the cost of the equipment to perform these tests would only add maybe 5-10% to the gearbox price on a run of say 50-100 gearboxes. It would give everyone a lot more peace of mind.
 
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I remember at least one of the Dawn Patrol guys having a Biplane with a Yamaha Virago Vtwin engine on it. You might google that for some information.
 
It's not the engine - it's the PSRU. Start there, and then look for an engine that will provide the power/torque required.

Seems that Geared Drives had broken the code in terms of vibration by simply adding the clutch springs back into the drive system. The accident stopped all that R&D....as far as I know, the engine/drive system was not at fault?

Carry on!
Mark

And I hear from a friend in Minnesota with a Geared Drive psru, the company is alive and well.

Here's the link with more info.

http://www.eaa.org/news/2012/2012-12-20_geared-drives-part-of-auto-PSRU.asp
 
Steve Wittman

The August 2013 issue of "Sport Aviation" has a great article by Lane Wallace called "Travels in Space-Time." I think it is probably her best one ever.

At one point Lane describes flying with Steve Wittman in Steve's Oldsmobile powered Tailwind when Steve was about 90 years old. I don't know the details of that particular conversion but thanks to Lane I now know how excited Steve was about it and the airplane.

In general I would say I don't want to fly in a home designed, home made airplane with an automobile engine flown by a decrepit 90 year old pilot. In this case, if I had had the opportunity, I would have been nuts to pass it up.
 
There are quite a few Yamaha 3 and 4 cylinder powered gyros and Kolbs flying. The engines seem to work fine for this type of flying.

Rotax C gearboxes appear to be popular on them so they must be easy to adapt. I follow along occasionally on the Rotary Wing Forum as these guys are pretty creative and always looking for economical powerplants.

While loosely on the subject of PSRUs, I saw last month that Tracy Crook of RWS will no longer be producing aviation products including his drives of which many were fitted to Wankel powered aircraft for over 10 years. One less choice in the gearbox market.
 
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Fact...there's a guy here in Alabama with a CBR Honda on a Drifter-class two place. Has a bunch of hours on it, like maybe 1000. Drives the airframe-mounted propshaft with the standard bike chain, using the standard transmission. And yes, he can shift in flight.

Gotta be careful about what you claim won't work ;)

Did not say it would not FLY, just why it is not a competitive option.

This must have been an Auburn guy, they can make ANYTHING WORK, that thing must have been great fun to get flying.
 
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My attempt!!!!!

Fact...there's a guy here in Alabama with a CBR Honda on a Drifter-class two place. Has a bunch of hours on it, like maybe 1000. Drives the airframe-mounted propshaft with the standard bike chain, using the standard transmission. And yes, he can shift in flight.

Gotta be careful about what you claim won't work ;)

...More years ago than I can believe or want to, I built a Taylorcraft BC 12-D conversion using a Kawasaki KZ-1000 complete engine assembly. We also had the transmission in tact and could shift in the air or on takeoff. In the air we only used the top three gears and this mimicked a constant speed as for as the engine was concerned. We used a Gilmer belt for the reduction drive to reduce the noise output. The engine package produced well over 120 HP and virtually made this 65 HP T-Craft into an animal. The package was very fuel efficient. absolutely vibration free, self contained charging and starting system, was practically indestructible with its fully rollerized crankshaft. And ooh the sound of that 4 into 1 exhaust! It was like flying a Ferrari. I put over 100 HR. on it, all trouble free before selling it to a guy in Brazil. The last I remember he said it was approaching 900 or so hours and still going strong. I loved this package and would fly it anywhere with confidence. I wish I had it back! Thanks, Allan...:D
 
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