Help with single rotor structures/craft?

[archnem]

I am loving the new robotics parts, but am having some trouble.  I've tried making spinning hab rings on craft, and single-prop planes and am having a real problem figuring out how to counteract the torque.  I just cant seem to make anything stable without doing things in twos for counter-rotation.  Those of you that are better at physics, math, or engineering than me care to give me some pointers?

[Vanamonde]

This *is* how physics works.  Any real spaceships would have the same problem. You're not doing anything wrong. 

[archnem]

But single-prop planes fly all the time? And I've seen screenshots of people with single-prop craft in KSP....I just want to know how they did it.  I am aware that this is how physics works, but I cant make my engine off-balance to counter the torque like a WW2 fighter would.  But sure, snark helps alot.

[Bartybum]

Relax, he's not being snarky.

Single prop aircraft have to deal with the unbalanced torque too. In KSP people just counter the torque with reaction wheels.

[bonyetty]

A joystick also helps a lot as it becomes quite natural and quick to put a lean on the stick to cancel out the torque. 

[Vanamonde]

Real pilots apply some trim and control surfaces as needed, since the amount of torque is proportional to how hard the engine is working. 

[IkranMakto]

That's why classic helicopters need tail rotor.

[KerikBalm]

On 7/17/2019 at 12:20 AM, archnem said:

But single-prop planes fly all the time? And I've seen screenshots of people with single-prop craft in KSP....I just want to know how they did it.  I am aware that this is how physics works, but I cant make my engine off-balance to counter the torque like a WW2 fighter would.  But sure, snark helps alot.

1) I think he was trying to be sympathetic, with his "you're not doing anything wrong"

2) I think its partly a consequence of low RPM engines. The lower the RPM, the lower the velocity of the blade, the higher the pitch needs to be. The higher the pitch is, then the more the lfit vector is pointed sideways instead of forward, and the more torque there is from lift in addition to just drag.

Higher RPM, lower torque should make the problem not as bad.

One Italian design in WW2 lengthened one wing to counteract the roll. Many designs just use contra-rotating props/rotors in real life, and that's what I do in KSP

[Daniel Prates]

I have to agree here, torque seems to be "too damn high", to quote the famous meme. I simply cannot make a workable single-prop, torque seems to be too excessive regardles of how I configure the rotor engine. 

When an airplene gains speed, the torque effect tends to yaw you to the side, more  than it tries to corkscrew you that hard, because of the airflow on the wings countering the torque force. My guess is that ksp physics do not account for the resistance wings put against the torque's angular momentum.

EDIT: I can make single props work fine, but with lots of blades and very, very low rpm, resulting bad performance. It doesn't feel right. 

Edited July 23, 2019 by Daniel Prates

[AHHans]

I don't think that the torque from the props onto the plane is too high.

I just made a single engine, single prop plane. It doesn't fly as well as its counter-rotating prop twin, but it does fly O.K. One major issue is that SAS "direction hold" doesn't correct for the constant torque, so it actually flies better using the manual trim without SAS. The biggest torque-related effect that I had was during landing, when I hit the brakes, at that moment the angular momentum in the prop turned the plane over. So I had to brake using the prop, by setting the blade pitch (authority limiter) to zero or slightly negative. (Which also helps against the planes tendency to faceplant when using the wheel-brakes.)

Here is a screenshot of the plane trimmed for stable flight: [Screenshot on Google Drive]

P.S. Yes, when you change speeds you need to change the trim. But that's not different on a real single engine plane.

P.P.S. I'll stick to counter-rotating propellers for most of my craft anyhow. They are more fun.