Re: Yaw control in a tandem rotor helo?

[Chris W]

Richard Riley wrote:
> I've been working with a conventionally configured helicopter for a
> few months and this suddenly started eating my brain.
>
> In a 2 rotor helicopter you are countering the torque of one rotor
> with the other rotor. But how do you do a pedal turn? In a coaxial
> I'd think you'd increase the pitch of once set of blades and decrease
> the other. But what do you do in a tandem, like a CH-46? Increase
> the pitch, you get more torque, but you also get more lift, so the
> aircraft would move forward or backward -
>
> Any helo pilots out there that can set me straight?

I have no clue if I am right but I always thought that stepping on the
pedals would be similar to a situation where you had a stick for each
rotor and moved them in equal and opposite directions. How that is done
mechanically I don't even want to think about.

--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
One stop wish list for any gift,
from anywhere, for any occasion!
http://thewishzone.com

[Morgans[_2_]]

"Chris W" > wrote

> I have no clue if I am right but I always thought that stepping on the
> pedals would be similar to a situation where you had a stick for each
> rotor and moved them in equal and opposite directions. How that is done
> mechanically I don't even want to think about.

I don't think so.

Banking a chopper with a stick tilts the mast because of the offset of
thrust on the one side. That causes the turn. To do so in opposite
directions with a tandem rotor would only try to twist the fuselage, and not
end up with any bank to cause a turn, assuming the you don't twist the
fuselage in two. <g>
--
Jim in NC

[Robert M. Gary]

Morgans wrote:
> "Chris W" > wrote
>
> > I have no clue if I am right but I always thought that stepping on the
> > pedals would be similar to a situation where you had a stick for each
> > rotor and moved them in equal and opposite directions. How that is done
> > mechanically I don't even want to think about.
>
> I don't think so.
>
> Banking a chopper with a stick tilts the mast because of the offset of
> thrust on the one side. That causes the turn. To do so in opposite
> directions with a tandem rotor would only try to twist the fuselage, and not
> end up with any bank to cause a turn, assuming the you don't twist the
> fuselage in two. <g>

It also causes the vehicle to yaw into the turn. I still remember my
instructor yelling at me to press the outside peddle (quiet odd for a
fixed wing pilot to do in a turn).

-robert

[Morgans[_2_]]

"Robert M. Gary" > wrote

> It also causes the vehicle to yaw into the turn. I still remember my
> instructor yelling at me to press the outside peddle (quiet odd for a
> fixed wing pilot to do in a turn).

I thought we were talking about tandem rotor choppers, and how they managed
to do things like rotate (change direction they are pointed) in a hover.
No?
--
Jim in NC