This is a neat trick to land but isn't it dangerous since you only have 1 chance to land? If you land without the TH on, you can always apply positive pitch if you're in trouble or correcting any errors right? I'm still new to CP and gotta ask questions.

Dangerous? Probably, but it is to my knowledge that all full size helis sold/made in the US have to be able to perform successful autorotations, and I believe pilots need to learn to do this also. I've read this in various places online, but if you think doing it on an rc heli is dangerous and sketch, picture it scaled up! Eeeeek!

Originally Posted by vincent713

This is a neat trick to land but isn't it dangerous since you only have 1 chance to land? If you land without the TH on, you can always apply positive pitch if you're in trouble or correcting any errors right? I'm still new to CP and gotta ask questions.

Not really dangerous, but you *do* need to get it right every time, cause, as you say, you only get one chance. Having flown hang gliders in the real world for the last 34 years, I've had lots of practice doing dead-stick landings. Sailplanes do this every time too.

With planks, the secret is keeping lots of airspeed all the way to the ground - same with helis and headspeed - (as long as you've got reserve headspeed you can always use positive pitch and the remaining rotational inertia to do a good landing). In fact, having low headspeed at the point of touchdown minimizes the potential damage from a blade strike (and this is why many (model) pilots use an auto for every landing - but they typically cut the power when pretty close to the ground then simply hover and bleed off the headspeed before touch down).

I do highly recommend everyone get a sim if they can afford it - practicing autos is really fun!

This is a weird coincident as I was reading the V931 thread, someone post a video of a heli who had an engine failure and had to do an auto rotation landing. Check it out.

AS350 Autorotation - with a twist (9 min 54 sec)

I won't lie. That video had my heart racing just a little. Cannot imagine what was going through his mind. So calm and collective.

"collective"- LOL, exactly

Originally Posted by pdooley

"collective"- LOL, exactly

Made a little pseudo pun there lol. I actually had to look it up, and found the correct phrase is collected LOL. I guess I've just never looked into it and have been saying the phrase that way forever.

In other news. I haven't flown my v911 in a few days :/. Been spending a lot of time on my mcpx. I need to fix this on the next calmish day!

For the experienced flyers out there.
Why when I turn left, does the heli lose altitude but if a turn right, it keeps altitude or even climbs ever so slightly? Throttle remains the same from what I can tell and feel.

Originally Posted by Saffa_V913

For the experienced flyers out there.
Why when I turn left, does the heli lose altitude but if a turn right, it keeps altitude or even climbs ever so slightly? Throttle remains the same from what I can tell and feel.

When you input a yaw command, it ever-so-slightly changes the load on the main rotor. You'll learn to compensate with the throttle.

Originally Posted by Saffa_V913

For the experienced flyers out there.
Why when I turn left, does the heli lose altitude but if a turn right, it keeps altitude or even climbs ever so slightly? Throttle remains the same from what I can tell and feel.

Are you talking about shifting left/right or rotating left/right? Either way, the answer is the tail rotor. Remember that the tail rotor doesn't just cancel the torque of the main rotor, it also pushes the heli sideways. That is why in level flight the heli leans into the trust of the tail rotor. If you look at the skids you will see small bumps that lean the helicopter while it's on the ground.

OK, so lets talk about sliding left or right. Remember that in hover the tail is pushing the heli to the left so the rotor is leaning to the right. When you move left the rotor becomes more upright thus 100% of the rotor lift (vs say 98%) is straight up and down. Assuming the controller doesn't slow the rotor slightly that extra 2% of the trust that was acting against the tail rotor is not lifting the heli (I don't know how much it actually but with some trig we could figure it out). Conversely, when you slide right you have to lean the main rotors even further so some of the thrust that used to support you is now pulling the bird to the right. That results in a small decrease in the vertical component of thrust. Hence the bird drops unless you speed up the rotor.

When rotating you have something similar. If you turn with the rotor reaction torque (rotate left, the tail rotor slows down) then the effective speed of the main rotor is slower. That results in the bird loosing lift. If you rotate the other way the effective speed of the main rotor increases as the total speed of the rotor through the air is rotor vs fuselage RPM+yaw RPM. Higher total RPM means more total lift.

Originally Posted by Saffa_V913

Why when I turn left, does the heli lose altitude but if a turn right, it keeps altitude or even climbs ever so slightly? Throttle remains the same from what I can tell and feel.

V911 is a fixed pitch helicopter. The overall lift remains constant.

But if you are moving forward, then the advancing blade (left side) has more lift than the trailing blade (right side).

If you bank left to turn left, then the advancing blade has to lose lift and actually loses more lift than the trailing blade can gain (it is fixed pitch).

Fast forward and turn right (bank right) and the advancing blade gains lift, actually more lift than the trailing blade loses.

Originally Posted by Ribble

V911 is a fixed pitch helicopter. The overall lift remains constant.

But if you are moving forward, then the advancing blade (left side) has more lift than the trailing blade (right side).

If you bank left to turn left, then the advancing blade has to lose lift and actually loses more lift than the trailing blade can gain (it is fixed pitch).

Fast forward and turn right (bank right) and the advancing blade gains lift, actually more lift than the trailing blade loses.

To be a bit pickier, the overall thrust remains constant. If we say lift is only in the vertical direction then it drops as we tilt the aircraft. This is obvious when we nose the aircraft forward to move forward.

actually thrust and lift are variable depending on RPM. The only thing that stays constant is the pitch.

Originally Posted by pdooley

actually thrust and lift are variable depending on RPM. The only thing that stays constant is the pitch.

True. I should have specified an assumption of constant RPM (at least until the pilot adds power). But the important point was that lift is the vertical component of the rotor (and tail rotor) thrust. When you tilt the aircraft in any way that angles the rotor with respect to the ground then your rotor trust isn't vertical and your lift is reduced given the same rotor RPM.

Originally Posted by meanscreen

To be a bit pickier, the overall thrust remains constant. If we say lift is only in the vertical direction then it drops as we tilt the aircraft. This is obvious when we nose the aircraft forward to move forward.

Interesting. "The overall thrust remains constant". To carry that to an extreme, if the rotor plain is tilted to the vertical, then lift is zero, and correct, lift is not constant.

So, we try this...
"V911 is a fixed pitch helicopter. The overall lift remains constant in the rotor plain."

OK, now I violate that by saying "bank left" or "bank right" (loses lift), or "fast forward" (gains lift).

My thoughts were that if you increase forward speed to the point where there is no wind over the retreating blade, then the pitch of the retreating blade does not matter, but on the other side the opposite pitch of the advancing blade will change overall lift among other things.