Yamaha Apex Skytrax Adapters

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Posted

I couldnt answer that question. Maybe jim hensel knows this. But until someone really figures out the 2011-2017 wire harness I think I would use the 2006-2010. The wiring and accesories are completely different between these group of years. Part of why the hp increase maybe because of power valves in the exaust which I cant imagine us using. I dont think anyone has even started looking at the later model harness. The good news with redrive options is the cases are the same so if someone ever tackles it we should have a drive

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Posted

Ok, I didn't realize they were that different. Thanks again for the info!

Clark

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Posted

Any idea what the installed weight difference will be to a 912 or 914? This is really exciting and I'll be making an engine choice for my SuperSTOL in the not too distant future...

Clark

Looks like Teal answered your question, but I wanted to add that with Steve Henry on your side you have a totally unfair advantage over the rest of us if you end up going Yamaha! 

If his headers, motor mount, and other fabricated parts would have bolted up and fit my KF like they would on a Just firewall I woulda bought them in a second!

Yes, it is great that Steve is really figuring all this out. It is nice to have the FF option from him. I look forward to more flight reports by him.

Clark

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Posted (edited)

The EXUP exhaust valves have the same advantage in a snowmobile as do the RAVE variants in Ski doo sleds.  They eliminate the comprimise between giving up low and midrange torque response for high rpm power. With the valves you can have the best of both worlds.  

If you dig deep in that article link it explains that better than I have but for an aircraft application the valves probably would not be necessary or easily feasible to work into a custom exhaust.  That may leave someone with a slightly less responsive midrange but that is less of a neccesity for an aircraft application and the peak HP should still be achievable (with a proper intake and exhaust build) since the valves are in the wide open position at peak HP/RPM.  Again the article explains how better breathing and a change in cam timing help account for the 150 - 162 difference.

I also for sure want to clarify here that wheras the RX-1 adaptation has been out in numbers and proven through some time (the reason I chose it over the Apex), the Apex is just in it's infancy.  Teal will be the first to tell you his prototype must be considered an unknown until it undergoes and passes extensive R&D.  The wire harness on V1 motors has only been modified by a few and the V2 harness is more complex and on the "to do list" as Teal mentioned. 

Reality is that there are only a handful of Apexs out flying so far (most well known being Steve Henry in his "Yee-Haw 6" Highlander) but with guys as smart and capable as Teal, Steve, and Ian I for one have no doubt that any growing pains will be overcome and we will look back on 2018 as the big year for this great engine option becoming available as a well supported and "doable" conversion.

And although this topic is specific to the Skytrax Apex adapter, it is only fair to recognize that this adapter is not the only way to connect a prop to the Apex.  I believe Tango Gyro also makes an adapter and Steve Henry is flying his Apex with a Mohawk Areo (Greg Mills) adapter, Rotax C gearbox, and centrifugal clutch.

 

Edited by Yamma-Fox

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Posted

This is the front face of the back half after the gearbox coming out of the mill

2018040895185029.jpg

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Posted

Engine mounting side

2018040895225947.jpg

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Posted

Shiny!

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Posted

Beautiful!

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Posted

New Skytrax gearbox fit up.

20180411_190316.jpg

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Posted

20180411_194344.jpg

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Posted

20180411_190654.jpg

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Posted

I'd feel pretty good about buying and owning something that nice.

Can't imagine how satisfying it would be to have actaully MADE it!!

Congrats Buddy!

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Posted

Thank you, I cant take all the credit I havent done much of the programming my buddy helped me out with the cnc programming based on my input. 

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Posted

That is awesome Teal! I'm sure it will perform as good as it looks. Can't wait to hear some flight reports...

Clark

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Posted

Congratulations! One should really place this piece of fine art on pedestal in the Smithsonian for the many to see. But even better will be the enjoyment of the few lofting them to cool places even though it is hidden under an aircraft cowling. Having had a chance to fly Willis' Fat Avid with the 1.O RX conversion I can't wait to see what 2.0 brings. Looks like it's about time to bring an end to my Subie days here and start thinking heart transplant for Nellie!  

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Posted

Initial engine runs are a success!!

20180414_123201.jpg

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Posted

Congrats - looks really good

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Posted (edited)

Update on teals progress here.  He incorporated an "in gear" sprag clutch prototype that looks really good:

Simple and space efficient, big huge diameter used in high power applications, well lubed in the oil bath of the gearbox, easily available at auto parts stores, inexpensive to inspect/replace.

A good HD sprag will really save some wear and tear on the gearbox and engine gear reduction components and also make starts much smoother.

Nicely done Teal!

FB_IMG_1527217886741.jpg

Edited by Yamma-Fox
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Posted

A sprag is just a one-way clutch.  

How does this help starting?

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Posted (edited)

Mostly smoother start transitions, not easier.

The starter is strong enough to spin up the prop.  The clutch allows the prop to override the motor momentarily as it fires off from starter speed and accels up to idle speed, helping keep the engine from getting into the sub-idle "shakes" where the prop and motor can get into a wrestling match.

Sounds like that helps especially with the bigger props used on this motor.

Edited by Yamma-Fox

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Posted

In flight with this system, on a long decent for example, the motor could slow from the point of engagement causing the prop to windmill.  Correct?

Has this system been flown yet?  What is that behavior like?

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Posted (edited)

Yeah it should work like my old NSI soob with a sprag..  in the descent like your example, anytime you pull power fast, and also during shutdown the prop will override and "freewheel".  That freewheel  (sprag override) will also happen for very short moments between engine pulses when starting and idling.

So a downside, like with a centrifugal clutch, is in an engine failure scenario where you cannot get the prop to stop windmilling / freewheeling. 

Also you need to tie down the prop on the ramp / trailer to keep the prop from spinning and the sprag from running dry  (since in those scenarios there is no oil being splashed up from gears spinning).

Edited by Yamma-Fox

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Posted

Oh and I forgot another reason to have the sprag, especially with big (high MMOI) props.  The Yamaha shuts down really fast and abrupt, with virtually none of the "coast down" that a 2 stroke has.

So without the sprag, when you shut down, the prop momentum is forced to stop abruptly as well, which also causes some shake and stresses with each fluctuation of deceleration from compression pulses.

With the sprag the motor shuts down how it likes and the prop just overrides and spins down like a free turbine turboprop.

Maybe teal can post up his vid of test run and shutdown with the sprag.

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Posted

This is not a new concept NSI and a couple other gearbox companies did this. As far as windmilling in flight, it will be the same as running a centrifigal clutch.

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