First Coaxial Helicopter Flight

[okikuma]

An interesting home built coaxial helicopter in either Indonesia or in China. Hard to tell since there are ethnic Chinese living in Indonesia. Note the Han characters on the building in the background.

Wayne

First Coaxial Helicopter Flight, STOL Aircraft Suyanto

 

[wolfy]

Appears to fly well. The collective swapped hands half way through?

wolfy

 

[timdrnec]

Appears to fly well. The collective swapped hands half way through?

wolfy

Looks like the video must be mirrored during part of the clip, the exhaust switches sides too

 

[Mayfield]

Impressive flying!

Sorry, have to put on my IP hat for those just learning to fly anything:

Note the erect but relaxed posture, and the smooth, miniscule movements of the collective and cyclic. Notice how he is looking pretty much straight ahead in hovering flight, picking up attitude cues with his peripheral vision.

I could quibble with his not looking in the direction of turn enough, but before every change in direction his head does turn slightly to clear the turn.

I have never flown an aircraft like this one, but it looks strange to me not having any kind of deflecting surfaces to assist yaw stability. I think I understand the basics of a coaxial rotor, but I'm puzzled. It would appear to me that the aircraft would at least need some side plate area behind the CG to assist yaw stability in forward flight.

All in all, very nice. I wish he would post here.

Jim

 

[okikuma]

Appears to fly well. The collective swapped hands half way through?

wolfy

I noticed that too Jamie, however I wasn't going to squabble over that bit of video editing.

Impressive flying!

Sorry, have to put on my IP hat for those just learning to fly anything:

Note the erect but relaxed posture, and the smooth, miniscule movements of the collective and cyclic. Notice how he is looking pretty much straight ahead in hovering flight, picking up attitude cues with his peripheral vision.

I could quibble with his not looking in the direction of turn enough, but before every change in direction his head does turn slightly to clear the turn.

I have never flown an aircraft like this one, but it looks strange to me not having any kind of deflecting surfaces to assist yaw stability. I think I understand the basics of a coaxial rotor, but I'm puzzled. It would appear to me that the aircraft would at least need some side plate area behind the CG to assist yaw stability in forward flight.

All in all, very nice. I wish he would post here.

Jim

Jim,

The pilot's relaxed posture and flying skill is definitely apparent. He obviously has flown helicopters previously. The lack of turning his head to clear his turn. I'm not at all surprised. Here in SoCal, I've witnessed daily and have almost been hit by many a driver in a vehicle that were born outside of the USA on our freeways and roads that did not turn their head to look before changing lanes or turning a corner. The same with walking across an intersection within a crosswalk or "jaywalking" across the middle of the road, looking only straight ahead.

Wayne

 

[Georgi]

Impressive flying!

Sorry, have to put on my IP hat for those just learning to fly anything:

Note the erect but relaxed posture, and the smooth, miniscule movements of the collective and cyclic. Notice how he is looking pretty much straight ahead in hovering flight, picking up attitude cues with his peripheral vision.

I could quibble with his not looking in the direction of turn enough, but before every change in direction his head does turn slightly to clear the turn.

I have never flown an aircraft like this one, but it looks strange to me not having any kind of deflecting surfaces to assist yaw stability. I think I understand the basics of a coaxial rotor, but I'm puzzled. It would appear to me that the aircraft would at least need some side plate area behind the CG to assist yaw stability in forward flight.

All in all, very nice. I wish he would post here.

Jim

"I could quibble with his not looking in the direction of turn enough" - The pilot could be just "crossed-eyed"?

 

[okikuma]

"I could quibble with his not looking in the direction of turn enough" - The pilot could be just "crossed-eyed"?

Esotropia?

or Exotropia like the famous actor Marty Feldman?

Wayne

 

[Oskar]

No tail feathers means yaw control is most likely done by differential pitch control. Which makes it's either a very complex or very clever yaw control system.

 

[Mayfield]

As I noted in Wayne's other coaxial thread, the lack of shake/visible vibration is surprising to me. Is there something special about coaxial helicopters?

I had never noticed this before.

Jim

 

[okikuma]

No tail feathers means yaw control is most likely done by differential pitch control. Which makes it's either a very complex or very clever yaw control system.

Oskar,

The simplest method is the vertical stabilizers deflecting rotor wash in a horizontal plane.

The next method is Rotor Tip Brakes to create drag on one set of rotors.

Rotor Tip Brake

The last method is to increase the collective pitch (increasing drag) on one rotor while simultaneously decrease the pitch (decreasing drag) upon the second rotor.

Wayne

As I noted in Wayne's other coaxial thread, the lack of shake/visible vibration is surprising to me. Is there something special about coaxial helicopters?

I had never noticed this before.

Jim

Jim,

Both coaxial and syncropters are inherently stable as compared to conventional helos. Think about twice the lift capability with two rotors under the same horsepower as with one rotor and a tail rotor. The UH-1 can sling load 3,000 lb whereas the Kaman K-MAX can sling load 6,000 lb with the same engine as a UH-1.

As for the cyclic shake and rotor balancing, all these small coaxial aircraft seem to get the rotors balanced quite well.

All the old films I've seen of Hiller's XR-44, there is some shaking in the airframe due to unbalanced rotors. Note the increased distance between the rotors from the first film as compared to the second film. Perhaps there was a rotor strike that necessitated the increase.

Wayne

 

[btd1982]

Oskar,

The simplest method is the vertical stabilizers deflecting rotor wash in a horizontal plane.

The next method is Rotor Tip Brakes to create drag on one set of rotors.

View attachment 1159328
Rotor Tip Brake

The last method is to increase the collective pitch (increasing drag) on one rotor while simultaneously decrease the pitch (decreasing drag) upon the second rotor.

Wayne


Jim,

Both coaxial and syncropters are inherently stable as compared to conventional helos. Think about twice the lift capability with two rotors under the same horsepower as with one rotor and a tail rotor. The UH-1 can sling load 3,000 lb whereas the Kaman K-MAX can sling load 6,000 lb with the same engine as a UH-1.

As for the cyclic shake and rotor balancing, all these small coaxial aircraft seem to get the rotors balanced quite well.

All the old films I've seen of Hiller's XR-44, there is some shaking in the airframe due to unbalanced rotors. Note the increased distance between the rotors from the first film as compared to the second film. Perhaps there was a rotor strike that necessitated the increase.

Wayne

Hi Wayne,

Personally I wouldn't agree that coaxial's are inherently stable unless the rotors are beneath you like the flying platform. Didn't seem any more stable than an R22 in my limited experience. Talking just about the cyclic of course and they are easier to fly in other respects. No torque balancing to manage for example.

Ben

 

[500e]

https://www.youtube.com/@stolaircraftsuyanto9728

 

[HobbyCAD]

Look closely, he has a Bell/Hiller style stabiliser bar connected to the top rotor. Probably makes it rock solid stable.

Nice machine though.