auto rotation

[wang_uk]

Today me and Jamie managed to get out and put some stick time in. Now i have just purchased phoenix R/C Sim and i can land auto's on there so i thought il have a play. Well in a hover about 3feet i flicked the the Th hold and the chopper drop like a sack of Sh*t with nearly no lift with full pitch.
Changed the pitch to 0,5,10 and tried again and it was a little better.

Now Jamie did the same but his could lift with no power and could land with no power and he is running 0,5,9 pitch and we both got head speeds of 17rpm. Any idea's as i want to do this from a hight?

[Stuart]

I assume you have differing blades ? but the same heli's
The inertia of blades differ, slightly heavier blades will hold the speed longer.

To start to learn full auto's, you will need to re-dial your head to give -4 to +8
Take your heli up high and facing into the wind and drop your TH to the bottom, now the engine goes to idle and the pitch to -4. If you have a nice breeze then you can do this near vertical, if your in a light breeze give your self a small amount of forward speed before dropping the TH.

Try to keep the nose slightly up to keep the wind flowing through the blades and the headspeed up, as you get to 6ft spool up and go for it again and again. Once you get confident then you can move to a full Throttle hold auto. I used to have some half decent auto's movies of my Fury, I think I have them at work on CD.

[jamiem]

same blades afaik. if they are not, then mine are century 550mm wooden blades, and his are original TT raptor 550mm wooden blades, so surely that would not explain the huge difference in behaviour?

[Stuart]

heli weight, drag in bearings, belt tension, paddle weight, clutch rubbing so many things will effect your headspeed when you flick on hold. I remember putting a set of SAB Carbon 71cm blades on the Fury and what a difference it made to the autos, yet the same blades on the Milli Pro didn't stand a chance with the weight of the heli.

[wang_uk]

Cheers all for the replay. well i have a 550m wood thunder tiger blades on at the moment.

[wang_uk]

So what should i do?

[Ade_Law]

wait until you break them then try a different brand.

Ade

[Disc]

Wouldnt the headspeed make a diffrence if his mate was running a faster headspeed that would make it auto better?

but when I had wooden blades they didnt carry the speed when it was slowing down on the ground. Carbon certianly carrys speed better.

[Smoothound]

Wouldnt the headspeed make a diffrence if his mate was running a faster headspeed that would make it auto better?

but when I had wooden blades they didnt carry the speed when it was slowing down on the ground. Carbon certianly carrys speed better.

Once you hit hold headspeed makes no difference at all, it's all about the blades ability to store energy combined with pilot stick inputs

[jamiem]

our headspeeds are the same, both running 1700rpm as checked, and both have the same (or nigh on the same) pitch curves. its very odd that we are both running near enough the same setup's bar the blades (which are both wooden but different brands) and the fact that stefs is a v1 mine is v2.

stef, have you checked that your transmitter doesn't switch to a different pitch curve when you flick throttle hold?

Jamie

[wang_uk]

Thanks to Jamie for pointing out my different pitch curve when flicked in th. Hold and Ade for pointing me to phoenix Sim my engine stopped today about 30ft. I manged to do a Auto with a little bump at the end. Just bent the legs back. I spend hours practicing on the Sim and today i had no choice to do one.

Oh the reason why the engine died was the fuel line spit near the top of the main tank. (bugger)

[jamiem]

good work mate was it inside the tank that it split?

[wang_uk]

yes. right next the the tank bung

[Steve]

I'm glad I read this thread last night.

I went up the field this evening and tried the first step of high altitude autos with my Sceadu. I flew the model in 'start-up' flight mode (i.e. tickover engine speed and -4 deg pitch at low stick) went up high down wind and dropped the throttle to zero and tried to get the model directly over the middle of the strip using only the cyclic & rudder until the last minute before bringing the pitch and engine back up.

Did it several times and the heli still lives! Wahey! Maybe next time I'll actually go for the throttle hold switch.

I much prefer flying it in idle-up, but this is a necessary learning curve I feel.

[Ade_Law]

i have found the best way (safest and fastest) to learn to do autos is to start with just good old fasioned 45deg descents with the power on. use a full linear pitch curve centred around zero either in normal mode or with a governor to give a nice constant headspeed on the way down. Start off coming down slowly (zero degs) and slowly increase the speed until you get to about -5.

aim for a spot 30ft out from you, directly infront of you. do this lots of times into wind until you can get it on the spot every time.

this teaches you how to control the position of the model and control the rate of the descent.

once you have the hang of that setup throttle hold with a raised idle speed so that if you do a baby auto in the hover you can slowly raise the pitch and just about hold it in the hover at full pitch once the headspeed decays.

now go and do your descents again this time using throttle hold. as you get used to it lower the hold value 5% and do some more, get accustomed to the amount of energy you have at the bottom.

over time drop the hold value down slowly until you get to idle.

A common mistake is in the flare at the bottom of the auto. A lot of people tend to overshoot then try to come down vertically from about 20ft up. This means you can run out of headspeed at the bottom.

Your 45 deg approach wants to end up about 20ft short when the model is at about 6ft from the ground. So the last bit of the approach is much flatter than the rest.

When you get to about 10ft up you need to start raising the nose a little, this presents the disk to the airflow better, will raise the headspeed and slow the descent. This raised headspeed will continue at around the same level until you get it into the hover which is then where it will decay.

what this means is that you dont need to be using positive pitch right up until the last min giving you more headspeed and time to get it stopped and ready for landing.

Ade