New Russian contraption

[twistair]

Probably another good example for stability issues discussion and some other topics as well: this thing was built in Moscow using a trike fuselage including landing gear and lower mast. Single controls, back seat is also a tank for AG-spraying (note orange filler cap). T-tail has standard tandem Dominator dimensions. There are some, say, strange things in the design itself but looking at this gyro I was mostly aware about it's longitudal stability and would like to see your opinions.
It has 28' DW rotor, weighs (stated by builder) ca. 250 kg empty.
The gyro was already flown for ca. one hour but I didn't see this myself.

Cheers,

[Friendly]

Alex , what engine is it using??

[twistair]

It's BMW Take-Off, 100 hp German motoconversion based on R1100 motorcycle engine with reduction gearbox.

Engine website (http://www.takeoff-ul.de/Motoren/motoren.html)

[scottessex]

That is really cool!

[Timchick]

I like the use of the trike fuselage and landing gear.

[scottessex]

It looks like when your sails wear out, step up to a gyro! :D

[WindRyder06]

Very cool Engine!! Crap it is pricy at $7200 US plus the price the gear box :eek:

Fly Safe,
Chris

[twistair]

Just don't be caught with engine weight - complete engine with gearbox, oilcooler etc weighs close to 90 kg.
Same guys who built this rotored cradle built also a couple of tandem gyros powered with these BMW:

[twistair]

I like the use of the trike fuselage and landing gear.

I bet this idea itself is very old (I'm asked about this regularly by local newbees) and it has certain disadvantages since proper trike fuselage isn't designed for rotary loads and peculiar properties.

[WindRyder06]

Wow almost 200 lbs. I really thought the weight would have been less.

Chris

[Doug Riley]

I would investigate the CG location. The Dominator HS is rather small and is not very far back from the CG. It is not capable of offsetting a prop thrustline that is more than slightly above the CG (nor was it designed to do so).

Furthermore, the designer should investigate whether the shape of the pod and tanks will pull the nose over in a dive. That is, determine whether the aerodynamic center of the fuselage is below the CG. The HS is not adequate to compensate for that, either.

A similar problem may exist in the yaw axis when the throttle is reduced. Tandem gyros sometimes have yaw-stability problems once the power is off.

Careful testing required!

[twistair]

Thanks, Doug,

This is exactly what I'm aware of. I suspect designers didn't pay enough attention to these issues. I told them about these concerns but didn't see they count them serious. Since I know exactly they do read this forum, I hope that they will be more careful after hearing this from skilled persons.
BTW, yesterday I saw this bird flying with one 85 kg person on board.
It was very calm day and the bird looked pretty nice at take-off and landing. It has composite main landing gear which seems to do it's job very good both on concrete and rough grass.
I told the pilot (he is not the designer of this gyro) that flying it too fast may be way dangerous and he didn't. Max level speeds were ca. 100-110 kmh. Looking at his flights I believe I noted some signs of pitch instability in level flight and yaw instability at approach. Pilot told that he felt generous increasing of forward pressure on stick when he slightly increased speed.

[Doug Riley]

Alex, in my opinion these issues should be investigated with SAFE tests, not flight tests at first! It would be far safer to use models, test trailers and so on. They cannot kill you the way an unstable gyro can.

[twistair]

Ah, Doug, it's the big problem here: most of our builders are too fast in their quest to astonish the world that they lose any prudence...
You'd be sirprise if you only know how many guys here state they are "skilled in manufacturing" gyros ;) Most of them even never soloed in gyro.

[Hognose]

The trike to gyro conversion, I believe, is popular in Australia. The OZ guys call them "gykes."

cheers

-=K=-

[jdalexa]

Actually, if it's 250 kg, it would be over 500lbs. empty weight.

[scott heger]

The one thing that concerns me is the strengh of the mast. If you blow up the second picture, you can see that the mast is not a square tube, but two flat metal pieces linked with either plates , or solid spacers and bolts. Does not look like it would be strong to a twisting force. What do you guys think?

Scott Heger, Laguna Niguel, Ca N86SH

[Alan Coats]

Same guys who built this rotored cradle built also a couple of tandem gyros powered with these BMW:


"Rotored cradle" - I like that.

Alan