Oshkosh ’18 LSA Grand Champion powered by YAMAHA YG4i


Unobtainium Member
Steve Henry was my first customer in 2013. Then, in 2017 he wanted one of my latest Mohawk Aero Corps (MAC) Yamaha YG4i gearbox adapters for the 150 HP Apex snowmobile engines which, unlike the earlier RX1 motors, has EFI - something that high-altitude pilots love for obvious reasons.

He had just started work on his sixth "Just" aircraft, and fifth "Just Highlander", the "Yee-Haw 6". He had it flying in time for the '17 season, and flew it to Oshkosh this year from his home on the western border of Idaho. Since my adapter was on it, I decided to make my first pilgrimage to Oshkosh and meet Steve there.

As I drove up on Thursday, Steve called and told me he had won every STOL competition event at AirVenture so far, and gave me the time and location of the final contest to be held Friday evening.

When it came time for Steve to compete, the announcer told the excited crowd that earlier in the week he had landed in 67 feet and wondered if he could best that now. His engine was noticably quieter than any other engine in the event, even as he revved up for take-off. When he released the brakes and hit the NOS bottle for another 40 HP (190 total calculated HP), it was wheels up in an incredible 57 feet!!!
I have never seen any FW take off in 57 feet in this weight class or any other. Have you? Is this some kind of record for the books? No big surprise, Steve won Friday night’s STOL competition too, making it a clean sweep for the week not just in class, but overall.
As I sipped my campgrounds store coffee and ate my toasted plain cake donuts (I stick ‘em in the bagel toaster to crisp the outside an warm up the inside) on a picnic table in the warm, Wisconsin morning sunshine, with a gentle breeze licking at my 3-day-old neglected shave, reading my EAA AirVenture daily free newspaper “Today”, I came across the announcements for all of the event winners.
It said you can only win in any category once, and never win in that category for a lower or equal place again. And I read on through the list of winners until I came to the following:
Steve Henry
Nampa, Idaho

I just heard someone ask, “Why is this of interest here, to the gyrocopter community?” Because it was the gyro guys who made this happen: first with Todd Reick’s Yamaha Vector YG3 Rotax C kit in 2007, followed by Ernie Boyette’s Apex YG4i AutoFlight kit in 2011, and then with Greg Mills’ RX1 YG4 universal kit in 2012 and again with the Apex YG4i universal adapter in 2017.

By now there are about 100 flying Yamaha’s, the vast majority being gyrocopters and gyroplanes. We now even have a gyroplane manufacturer who is selling Yamaha-specific Eurotub air frames, known as TangoGyro.

With the announcement of a Yamaha-powered EAA Grand Champion which also won every STOL event at AirVenture 2018, it is safe to say that Yamaha aircraft power has most definitely arrived, and is apparently here to stay.


Active Member
some good news for the various Rotorcraft winners too

Helicopter - Gold Lindy
Russell Kunz
Neosho, Wisconsin
Safari 400, N615RK

Helicopter - Silver Lindy
Geno Mancini
Mountain Iron, Minnesota
RotorWay Turbine, N420SX

Gyroplane - Gold Lindy
Chris Toeppen
Atherton, California
Auto-Gyro Cavalon, N40CT

Gyroplane - Silver Lindy
Andy LeBoeuf
Gheens, Louisiana
Auto-Gyro MTO Sport, N217LL

Gyroplane - Bronze Lindy
Gregory Spicola
Brooksville, Florida
American Ranger 1, N205AR

Gyroplane - Bronze Lindy
Dayton Dabbs
Taylor, Texas
Magni M-24, N678HJ


Does that engine have one of those built in cassette gearboxes? Does one just get it to a certain gear and leave it there?


Unobtainium Member
Sounds like you thinking about motorcycles. This is a snowmobile engine, the APEX model. The external gearbox is attached to the engine by means of an aluminum adapter which is fastened to the crankcase on the PTO end of the motor. The gearbox is not a transmission, it is a transfer case that is a propeller speed reduction unit (PSRU).


Unobtainium Member
No Title

OK, so, like the wife, I am the last to know. These New Jersey guys have a company they call GyroDyne, bought out Ernie Boyette's RFD, like...last year??? wow. Flying under the hood, that's me. I just found this out while I talked to these folks as they were dismantling the c1960 Porsche-powered (certificated ? aircraft engine) contra-rotating helo (I don't recall the name of this machine, tho I've seen many photos of it on RF in the past.) that they plan to re-introduce in the future. As Stephen King's gunslinger would say in the Dark Tower series books: "The world has moved on."



Unobtainium Member
No Title

Rotorvox. This guy was asking if I could help him get his gyro company listed on the Rotaryforum mfg list. Please take a number...

This gyroplane was overheard whispering in my ear, "Yamaha me, pulleeeeeze!"



Unobtainium Member
Well, that's about it. The Red Bull helicopter was fascinating to watch roll over, and over, and over, and flip and even do a backward roll. Backward roll??? Wasn't expecting that one, no sireee. But there it was, in all her splendor and glory. That alone was worth the trip from Columbia, SC to Oshkosh WI.


Sling-Wing Pilot
Hey just for FYI Steve Henry Flew from Idaho to Oshkosh, looks like the Yamaha is proving itself very well! Congrats Greg, and Steve!!


Unobtainium Member
My first Oshkosh was a BLAST! It was my son's 30th birthday on Friday, July 27, and he only lives 60 miles from the event, in Madison so I got to do both. While I was browsing around on Saturday I heard someone say, kinda overly loudly behind me, "Hey, is that Greg Mills? Is that GREG MILLS?" I turned around, and there was Barry Kroplin and the Barnstormers gang! The people you run into when you don't have a gun, LOL. Jez kiddin.