General Heli gains alt. ... why?

[bigone5500]

When flying into the wind it seems that my 120s wants to gain altitude. I have tried to figure this out but don't understand it. The only thing that makes sense to me is it basically is acting like an airplane taking off into the wind. It's just easier to climb when into the wind than with a tail wind.

 

[Tony]

This is what is known as Translational Lift. This is when clean straight air hits the rotor blades providing more lift than still stagnant air or air that has already been put through the blades once or more which is known as dirty air.

 

[bigone5500]

So the clean air is pushing against the bottom of the blades? This makes an increased force upward on the airframe I guess. So if I understand it correctly, the rotor is creating lift while turning and the straight ahead air is adding to it, right?

 

[Tony]

Not against the bottom of the blades, it's just cleaner, more efficient air all around providing more lift given the same amount of blade pitch.

 

[bigone5500]

Not against the bottom of the blades, it's just cleaner, more efficient air all around providing more lift given the same amount of blade pitch.

Tin foe!!! Thanks Tony.

 

[Tony]

My pleasure. I don't get to talk about translational lift near enough lol. That is also why your helicopter will go up and down in variable speed winds.

 

[bigone5500]

My pleasure. I don't get to talk about translational lift near enough lol. That is also why your helicopter will go up and down in variable speed winds.

And that bugs the crap out of me. Wind will pick up and as light as the 120 is, it will still climb. Where I live that is not a good thing. These trees out here got arms man I'm serious. With the rotors at a slow speed, the heli can't go forward fast enough to get away from the tree tops. Very hairy situation it can be.

 

[Tony]

Oh trust me, I know all about it lmao. The trees too. The best thing you can do in that instance is push forward on the elevator to try to nose the helicopter back down to earth.

 

[Smoggie]

Transitional lift happens whenever the heli has any forward speed through the air. It can happen just the same flying 'downwind' or 'crosswind'. It's the speed of the heli moving through the air that counts.

It's easier to control the up and down 'ballooning' with a collective pitch heli.