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HelicopterMain Discussion › How much negative for AUTOS?
10-22-2004 01:59 PM  13 years agoPost 1
captainburgers

rrNovice

Derbyshire, Great​Britain

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Hi all
Whilst I realise that if an engine failure occurs and an unplanned auto is attempted you are stuck with whatever pitch-range you have set for that particular flightmode (eg. idle up 1).
I am however interested in your thoughts on how much negative to set on the bottom end of the throttle-hold curve (for practise autos).
I have already read much and talked to a few people and the general opinion is split into two camps!;
1. set a high negative pitch (eg. minus 10 degrees)so as to really increase the Rotor RPM.
2. set a lower value (eg. minus 2-3 degrees) the theory being any more pitch (albeit negative) will just create extra drag and in reality for the ammount of blade loading of a model heli will not really increase Rotor RPM without a massive loss of height (usually not available)
Any thoughts I am trying to limit the repair costs for this exercise!!
Regards
ADAM

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10-22-2004 02:11 PM  13 years agoPost 2
Drunk Monk

rrProfessor

Preston, UK

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If you use too much negative pitch you slow the blades down. -4 is supposed to be about right. When I do an auto I have -10 available but have the stick about 1/4 which would be around -4/-5 degrees


Stephen

I only open my mouth to change feet.....

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10-22-2004 02:26 PM  13 years agoPost 3
greenboot

rrVeteran

Marblehead, OH

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If you make the hold curve exactly the same as idle up and normal curves, switching modes will be easier. This might be important if you make a low altitude bail out.

I have found sucessful auto's are possible with a wide range of pitch. It's really not difficult to manually control pitch while you "fly" down the glidepath.

Tom

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10-22-2004 02:39 PM  13 years agoPost 4
bobj

rrVeteran

United Kingdom

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Hi Adam

I would say go with option 2 until you have practised a lot of auto's, with experience you can "fly the pitch" on the way down and so constantly change the amount of negative you are using depending on the required decent rate but to start with just set about -3 as you won't yet be capable of the fine control of the pitch you need to use if you have a lot more negative.

Cheers
Bob J

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10-22-2004 02:48 PM  13 years agoPost 5
z11355

rrMaster

New England

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Whilst I realise that if an engine failure occurs and an unplanned auto is attempted you are stuck with whatever pitch-range you have set for that particular flightmode (eg. idle up 1).
No, you're really not. In the vast majority
of the cases, you simply flip into throttle hold
mode.

The problem is that as an inexperienced pilot,
it's hard to remember to do that reflexively
when you have an unplanned auto.

And just to expand on what the others have
said, remember, learning these things is
an iterative process. You start w/ not alot
of pitch range or cyclic and as you get
experience, you expand the range.

-3 or -4 will keep you out of trouble and you
can simply bang the collective all the way
down. After a while, you can/will learn to
modulate how much negative you want
to fly down a specific glideslope.

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HelicopterMain Discussion › How much negative for AUTOS?
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