Hi, I've been wondering this for awhile and after an incident today while flying, I thought I'd ask.

I understand how a gas heli can auto because once the engine dies, the clutch will disengage and the rotorhead will be free to spin. What about on an electric? I have an MX400 and the motor is geared to the main shaft. When the motor quits, the rotor slows down VERY quickly because it is still engaged to the motor which provides a lot of resistance. Is it possible to auto an electric?

Incidentally, today while I was flying at about 10 feet up in the air, the motor suddenly quit. The heli dropped (I immediately increased collective for whatever good that did). Luckily there was no damage. I still don't know why the motor quit. On the ground I check all the connections, they were good. Then when I put the throttle at minimum, I heard the "churp-churp" of the ESC like it does when it initializes. Then took off and flew the remainder of the pack. Totally inexplicable power loss....

Yes, you can auto an electric. There's an autorotation clutch in the main gear...at least on the T-Rex and I would assume on the MX400. When the motor is not exerting torque on the gear, it free-spins. If your heli is not doing that, you may have a bad clutch.

Hi, thanks for the info. You are right, if my motor is not spinning, I can turn the rotorhead as you say. But it doesn't spin too easily, probably because of the driven tail. The thing is, once I land the heli and put throttle to minimum (engine off) the rotor will spool down to a complete stop in about 3-4 seconds. Is this normal? Doesn't seem like much time to do an auto!

After you can auto a trex, anything else is a piece of cake.

Mike

Loosen up the tailboom a bit, no need to pull the belt too tight. Spool down time varies according to pitch and blade inertia. For a good pair of blades at good rpm and zero degree pitch, I think a complete stop in 4 second is not good enough.

Clement

You have to be extremely good to auto a 400. There is absolutely no room for error and your timing has to be spot on.

I've auto'd my HB Cool once or twice and while some will say it's impossible to auto a micro, but it just takes perfection to pull it off. I did one auto from about a hundred feet once when I thought the motor started to cut. Dropped the collective and headed for the ground maintaining rotor speed until at about 6-8 feet up I started to cushion the descent with cyclic and light coll pitch. That was all it took to bleed off the rotor and drop out of the sky. I would have done better waiting until one foot up to pull collective and cushion the fall. Not pretty but workable.

A too tight belt will rob rotor inertia and so will pulling in collective to arrest a descent. You want to keep wind going through the blades and that means dropping, not maintaining altitude when doing an auto with these little birds.

to do a auto dont you need speed, so if your only a few feet off the ground your not going to have much speed but if your way up 200 feet then you have all that room to built up speed, then you can auto

if you're only a few feet up just maintain 0~3 degrees pitch or so and let it ooz itself in. A high speed descent is required when you're high up because it's the only way of coming down to a few feet high without loosing head speed, or when you have a low rpm to start with. Many larger helis can come straight down (level), and not very fast, at -2 degrees pitch or so and actually speed up the blades you can hear the whooshing sound of it and be comfortable knowing there's plenty to expend. I must admit I haven't experimented this with these little e-birds tho the blades are less audible and a blur dot high up there, so it would be safest to give it 0~-1 degrees pitch and dive right in as fast as possible to preserve rpm plus you can also pull cyclic at the foot in addition to relying on collective alone.

Clement

Rays DVD E series he mods the trex to take away the driven tail. It appears to auto much like a 30 after that. I was fairly shocked, my Trex auto'd like a homesick lawn dart.

Check [link=http://www.hjnet2000.com/faqs/index.php?View=glossary]this Glossary[/link]

This is a good article on auto-rotation: http://www.rchelimag.com/pages/howto...owto=13&page=1

I have a question: How do you practice an Auto-Rotation on an electric heli?

How do you kill power to the motor while flying without losing control of the cyclic? [sm=72_72.gif]

Tx, Onad

Throttle hold shuts power down to the motor, its the same as it being on the ground before you spin it up, the servos work and the motor is off, throttle hold allows you to use the collective with the throttle still at off (idle for nitro ships)

I should have specified that I have a CP Pro with stock transmitter. There is no Throttle Hold switch....

you'll need to upgrade your Tx is basically the answer in short =)

If you go with futaba or hitec you can use the stock receiver. You might also check ebay for a used Tx, they go for really cheap there.

You won't be auto'ing a CP Pro anyway so don't worry about it. If a CP hits the ground in less than 5 pieces, consider it a successful auto.

Yah, that is what I thought. Tx, Onad
True! Very True!! [sm=spinnyeyes.gif]