RV9 200HP Yamaha Sidewinder
 

Hello everyone,
I removed a Lycoming 0-235 from my RV9 and installed a Yamaha Sidewinder snowmobile engine. I know, I know I'm crazy what did you do that for....etc. The engine currently in stock tune on the fully programable ECU is set a little over 200hp from sea level to about 10kft. Currently at 15kft I can still make about 165hp according to the engine display.
It will climb out of my 1000MSL airport at over 2500FPM and at 15kft it will still climb at about 2000FPM.
Currently I can not maintain full throttle with OAT's above about 75f but I am installing a new radiator soon that should cure that.
I currently have only 7 hours of testing but the numbers are really great so far. The weight is 31lbs lighter with this engine over the 0-235 but I added the constant speed propeller. I also used the OEM cat iron exhaust manifold since I needed the weight. I pushed the engine away from firewall and used the stock turbo location which is between engine and firewall. Pushed the battery out on the engine mount and the CG ended up within .2" of the previous CG.
Biggest challenge currently is keeping the engine from overheating during Taxi but I will be adding radiator fans shortly for that.
I do not have real good fuel flow numbers yet at the lower Hp's. I know that it will burn 19GPH at wot anything under about 12kft. but that will yield a true airspeed of about 205MPH.
I am currently unhappy with the propeller blade selection for high altitude performance. It seems that there is not enough blade surface area to absorb the HP in the thinner air. Currently shopping for other options.
here is a few pictures of the install and the aircraft.
http://https://www.dropbox.com/s/ocl...r /> .jpg?dl=0
https://www.dropbox.com/s/ptfvkkhmwu...82354.jpg?dl=0
https://www.dropbox.com/s/jruwz1yu24...35945.jpg?dl=0
https://www.dropbox.com/s/qi04xaqg8c...mount.png?dl=0

That’s pretty cool! Please keep the info coming. I’m holding out for an affordable turbine. 😳

Pics posted from Dropbox link:

Attachment 27218

Attachment 27212

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Welcome to VAF
 

Teal, welcome aboard the good ship VAF :D:D

Congrats on the successful conversion to the Yamaha.

Did you consider the factory VNE numbers??? Methinks you are very capable of blowing well past them.

Good luck with the continued test, and please keep up with the reports.

Bravo
 

Bravo, bravo, well done.

Please keep it safe.

Keep up the reports! I have flown other aircraft with the Yamaha engines, and have wondered when someone would try one on an RV….so it will be great to hear your experiences. As has been pointed out, watch those TAS Vne numbers….and have a blast!

Reduction Drive?
 

Is the reduction drive from Yamaha? Is it designed for the thrust load?

Very cool! :cool: Keep us updated as you build more time on it.

Your latest gearbox Teal?

https://www.skytraxusa.com/

https://www.skytraxusa.com/new-page-1

That looks very well done. It would be great if you keep us updated.

The reduction drive is SkyTrax specifically desgned for this engine. Yes, designed for much more thrust than this.

The VNE numbers published by VANS are in indicated airspeeds. I am surprised that I am getting so many comments from current RV aircraft owners that are saying watch the TAS VNE numbers. I do appreciate the concern for my safety and helping me look out but I am aware of the 210 MPH indicated air speed VNE of the aircraft. The goal is to utilize high altitude thin air to achieve 210 plus MPH true airspeed but indicated airspeed will be less than than 180MPH. I conservatively drew a red line on my airspeed indicator at 180MPH. My last flight at 15kft I was indicating 161MPH but true air speed was a bit over 200.

Yes, "Nytro" gearbox

At current HP levels (205hp) at 2000MSL. I can achieve 194mph IAS at wot straight and level flight.

The Vne numbers provided by Vans are IAS or TAS, whichever is the most limiting

Please educate me.
Where is that published by VANS?
True airspeed can greatly differ from indicated airspeeds at higher altitudes where turbo aircraft air capable.

Page 3 directly mentioned Vne being TAS, but this entire PDF is applicable.
Sorry to be the one to give the bad news.

https://www.vansaircraft.com/wp-cont...1/hp_limts.pdf

You can also learn more in this thread: Vne: Indicated -v- True Airspeed

And that is exactly why Vne is TAS based.

I would love to see a low pass video of this engine. I bet she sounds wicked when wound up. Keep up the good work.

Thank You for all the information. I will study it closely and carefully consider The TAS numbers in my VNE calculation.

It is the truth. VNE for these planes are TAS.
Ignore this at your own peril.

Nobody joking here Teal. The RV-7 and the RV-9 share the same vertical stabilizer and rudder. Our community has already suffered some fatalities due to apparent flutter during known overspeed events. So far, I think they have all been 7's, but please note the 7 is standard with 180HP, some have as much as 215, and acro is allowed. As you know, a -9 is typically 160, no acro . No prize for being the first pilot to rip a -9 rudder.

I do appreciate every ones concerns for my safety. I think conservatively maintain the TAS numbers under 210MPH for this application is prudent anyways and I will do so. Again thinks for sharing the information.
To use TAS instead IAS as VNE is conservative and a way to keep from having to do calculations to see how much fludder margin there is at a given altitude and speed. I am fine with that. But to point blank say VNE for these planes, TAS and IAS are the same is a fallacy.

WOW Teal,
Great work! Please keep us updated.

IAS and TAS
 

After all these years, I’m amazed that we are still discussing the IAS and TAS limitations on the RV. Last week I had this same discussion with a know-it-all airline pilot who simply did not agree that these planes are TAS limited.

I love my RV-9 but descending out of 17,000 ft is a TAS exercise that I never had to worry about in my Aerostar or Comanche. I love the high flying efficient -9 but it’s a different animal that requires fitness. The margins are tight on that rudder.

Good job taking the advise of the folks here about TAS. Nobody here wants to lose yet another RV driver due to willful ignorance. We love the design, especially the -9.

Ok, I am going to add to this conversation as a fellow RV9A flyer who is running a higher HP engine than the recommended max 160 HP recommended by VANS.

PLEASE NOTE! VNE is NOT the only restrictive speed to pay attention to when flying an RV9(A). The point others have made concerning TAS vs IAS is valid not only for VNE but also for MAX cruise speed. And, you are familiar with the maneuvering speed right (118mph)?

If you thoroughly study the article written many years ago and sent out by VANS about speed limitations of the RV9(A) there is a substantial amount of print devoted to the MAX cruise speed for the 9 (which is also based upon TAS). There are “margins” to pay attention to in cruise also and NOT just at the max VNE speed.

Your experimentation is very interesting. I wish you the best and look forward to your findings. More than anything else though, I look forward to talking to you in person someday at OSH, Petit Jean or some other fly-in. If you pay attention to these things being posted here, I am confident you will have a lot to show and tell us at those gatherings.

[quote=RVbySDI;1614914]Ok, I am going to add to this conversation as a fellow RV9A flyer who is running a higher HP engine than the recommended max 160 HP recommended by VANS.

PLEASE NOTE! VNE is NOT the only restrictive speed to pay attention to when flying an RV9(A). The point others have made concerning TAS vs IAS is valid not only for VNE but also for MAX cruise speed. And, you are familiar with the maneuvering speed right (118mph)? [quote]

If you thoroughly study the article written many years ago and sent out by VANS about speed limitations of the RV9(A) there is a substantial amount of print devoted to the MAX cruise speed for the 9 (which is also based upon TAS). There are “margins” to pay attention to in cruise also and NOT just at the max VNE speed.

—————————————————————————————————————-

OK, now I’m confused. I thought that the redline Vne was based on TAS for meeting designed flutter margins. Isn’t maneuvering speed and max structural cruising speed based airframe structural load limits? If so, doesn’t that depend on IAS (calibrated)?

Let's limit the fear mongering and get the facts straight. What is it that you are calling max cruise speed, as that is not a std aviation term? If you are referring to Vno, which is NOT a max cruise speed, that is related to the speed below which a 50 fps vertical gust will send the wing into a stall before reaching the structural load limit of the wing. Those dynamics are always measured in IAS, as stall speed is always related IAS not TAS, and Van's has no guidance suggesting TAS should be used instead of IAS for Vno. Generally speaking, Vno is recommended as a max speed in conditions OTHER than clear, non-turbulent air. The challenge with Vne is flutter and flutter is based upon velocity and not wing lift dynamics, therefore TAS and not IAS. Many other planes get away with IAS limit, as they just don't go fast enough at ANY altitude to warrent a TAS limit.

Larry

I am referring to the article written by Ken Krueger and the graph on page 3 that can be found in this article:
https://www.vansaircraft.com/wp-cont...1/hp_limts.pdf

To be clear, my post is not motivated by “fear mongering”! I am making statements about maneuvering and “MAX cruise speeds” (call it what you will but it is addressed by Mr Krueger as Vc) to make note of these speeds that are important to structural integrity not risks of stall. Both of those speed concepts exist so that pilots can be aware of structural limits of the airframe. That structural integrity is why VANS wrote the above referenced article! The speeds listed that fall outside the margins of the “cruise envelope “ referenced in that graph are not labeled “stall”. They are labeled “STRUCTURAL DAMAGE”. The graph refers to the upper limit of cruise speed as Vc. That is what I am referring to as “MAX Cruise Speed”. Anything above that up to Vne is putting the airframe outside the “safe” envelope the airframe was designed to operate in.

I too have had questions about IAS and TAS, since VANS does address Vne as TAS speed but labeled the graph as IAS. For my flying I use TAS for every speed except stall. It is my opinion that TAS is a more accurate measurement of the airplane’s actual speed moving through the air and therefore is a more realistic representation of what impact that atmosphere will have on the plane as it travels through that air. It is that atmospheric environment that will ultimately impact the airframe.

Live Long and Prosper!

IAS, or more accurately, calibrated airspeed (CAS), includes the effects of air density, and thus is the appropriate speed to use for everything except flutter. CAS is what the structure is designed for.

Dave

Vno IS related to structural integrity. The concept is that a vertical gust can create G loading beyond the capacity of the plane. Vno is a limit whereby below it, a 50 FPS vertical gust (FAA guideline for determining Vno) will cause a wing stall, thereby reducing the G loading BEFORE it reaches the limit (the upper line on the envelope chart). Above Vno, the limit is breached before the stall happens. I am guessing his article is related to that. Will need to read it again, but the last time I read it, he even showed the loading envelope and explained in detail what I summarized above as his rationale for limiting speed. His main point related to the 9, because of it's structural limit differences relative to the other RV's.

Larry

You understand that, by definition, Va depends on stall speed. So using TAS for Va is some sort of circular logic.

Larry, I think you’re mixing concepts. Va (maneuvering speed) is where the wing stalls before exceeding design limits. At and below Vno, a 50’ per minute vertical gust is insufficient for the wing to exceed design limits. But the wing won’t come close to stalling.

Correct, that's the distinction between Va and Vno - but it's 50 feet per second, not minute.

At Vno, if you encounter a vertical gust IN EXCESS of the FAA standard 50 fps, then you can cause structural damage without stalling the wing.

The question I've always had is, how common is 50 fps vertically in weather? Thats 3000 feet per minute - 34 miles per hour. Seems to me that some decent building thunderstorms can easily reach that, even before they would be considered "mature". Stay out of convection, always and forever.

But back to the soup du jour - yes, Vne is in TAS, Vno and Va are IAS. Respect the limits, enjoy the horsepower.

Yes, I inadvertantly combined the concepts. Still relative though. Vno is just the speed at which the 50 FPS vertical gust can create structural damage by exceeding the wings G load rating. Va is about G loading due to pilot induced full control action vs vertical gusts, though I am sure it a applies to vertical gusting well beyond 50 FPS.

Larry

Time out....

Let's return to Teal's Yamaha conversion.

Ok, so I brought up maneuvering speed, and more specifically, the upper cruise speed of VANS graph to reference other limiting speeds to be aware of in addition to Vne. I was not trying to say that TAS was the correct speed measurement to use for measuring Va. Whether any speeds be measured using IAS or TAS based was NOT my relevant point.

I was specifically attempting to address the upper cruise speed that is labeled Vc on the graph in the referrenced article to point out that; beginning at that speed, there can be structural damage, given certain atmospheric conditions, before one reaches Vne.

As DanH has requested, I am interested in hearing more on the performance of this Yamaha engine setup. So, I will end my posts and look forward to reading more about it.

Live Long and Prosper!

What is the displacement of the Yamaha?

The speed reduction gears at the links that DanH posted seem to have large reduction ratios, suggesting the engine is turning at very high RPM.
What is the expected lifespan/TBO of this engine?

The light weight, and especially the performance at altitude are very appealing, but it must be a screaming mimi in there!

Electric C/S prop I presume? How do you like it?

Looks great Teal, looking forward to seeing how this goes. I was lucky enough to fly with Steve Henry behind his Yamaha Highlander and it's truly a monster for power. They've been working hard to make the gear reduction unit reliable. Thanks for sharing!