The dissymmetry of lift on a conventional helicopter in KSP.

[dok_377]

I created a feedback report explaining the situation in detail. 

https://bugs.kerbalspaceprogram.com/issues/24853

[Shadowmage]

That is actually a normal effect on a helicopter. 

In a 'hover' the forces of the rotors are roughly balanced out; neither side is generating more lift than the other.

But when you start moving forward... think about it... the blades are spinning, and the helicopter is moving forward.  The blade that is advancing into the airstream (direction of travel) generates more lift than the one that is retreating.  Thus you get more lift on one side (the advancing blade), and a roll is induced about the longitudinal axis towards the side of the retreating blade.  The pilot must correct for this by including additional cyclic controls to counter the roll.

[OHara]

The question is: should KSP's Breaking Ground have a feature to help us with the mix of pitch- and roll-cyclic needed to give level forward flight ?

In physical helicopters, that asymmetric lift tilts the angular momentum of the rotor so as to lift the forward side of the disk, so the tilted disk slows the forward motion. You use mostly forward-stick to keep moving. On a physical helicopter there is an advance angle so the forward cyclic pitches the blades to give left-right asymmetry, compensating the effect in the OP..

KSP's rotor disks have strangely small angular momentum, needing rather less phase advance than the 90° in simple descriptions of helicopters (KSP-BG implemented 0°) so there a mix of significant pitch and significant roll is required for level forward flight.   

Maybe KSP-BG could add a slider to the blades to let us set the advance angle (currently 0°) but maybe that is not worth the complication.

[EnderKid2]

I'm running into a similar issue in Stormworks, where my high-speed helicopter with a pusher prop uncontrollably rolls beyond around 80 m/s due to retreating blade stall.

[Rpatto92]

On 2/28/2020 at 9:54 PM, EnderKid2 said:

I'm running into a similar issue in Stormworks, where my high-speed helicopter with a pusher prop uncontrollably rolls beyond around 80 m/s due to retreating blade stall.

 

On 2/14/2020 at 12:21 AM, dok_377 said:

I created a feedback report explaining the situation in detail. 

https://bugs.kerbalspaceprogram.com/issues/24853

You both need to look into articulated rotor systems, specifically the terms; feathering, flapping and hunting. I've just posted a comprehensive guide for exactly this reason. 

Here's a link: 

 

On 2/28/2020 at 6:13 PM, OHara said:

KSP's rotor disks have strangely small angular momentum, needing rather less phase advance than the 90° in simple descriptions of helicopters (KSP-BG implemented 0°) so there a mix of significant pitch and significant roll is required for level forward flight.   

Sounds like you have some insight into this topic worth exploring. That may be something that could be tweaked in a config, that might be a useful mod. Perhaps, check out my demo single rotor helicopter: https://kerbalx.com/Rpatto92/Huron-Hunter-M-11 and tell me how you think I should tweak things... (craft, configs, etc.

Also, check out my guide:  

It makes single rotors' viable but perhaps there's some ways it could be improved. 

[dok_377]

22 hours ago, Rpatto92 said:

You both need to look into articulated rotor systems

Why are you necroposting in a post that was created more than 3 years ago? Even back in the day I knew how helicopters worked, the post wasn't about that at all. 

[Rpatto92]

2 hours ago, dok_377 said:

Why are you necroposting in a post that was created more than 3 years ago? Even back in the day I knew how helicopters worked, the post wasn't about that at all. 

The issue you left feedback about is addressable in-game; once you've worked around the buggy robotics. That's why I replied to you.

You may well know how helicopters work but actually implementing that in-game took some figuring out. I'm just attempting to revive interest in helicopters by reaching out to some people that have posted in past. There really hasn't been a lot of recent activity, so as you can imagine I looked back as far as 2020 because that's about how long the issue of dissymmetry has stayed unresolved in-game.

Sorry, if you found this annoying. 

 

 

[dok_377]

6 minutes ago, Rpatto92 said:

Sorry, if you found this annoying. 

No, not at all. I was just wondering why I received a notification about this old post that I long have forgotten about. All good.