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HomeAircraftHelicopterMain Discussion › Autorotation- what is most efficient negative pitch angle?
03-09-2012 07:26 PM  6 years agoPost 1
S Crutchfield

rrNovice

Arkadelphia,Ar. usa

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I have been experimenting with auto's on the sim, trying to compare the amount of headspeed deteriation in relation to different pitch setting.It seems like there is a point were too much pitch will slow the blades, even when done gradually. Let me say I am new to auto's and would like to know as much as possible before I try it for real.
I just built my first 800 gasser. It's the first really nice heli I've owned so I'm not ready to botch my first attempt.
Also what about throttle hold pitch curve? Do you guys keep It linear or limit the throw on the bottom?
Is it possible to overspeed the rotors with too much negative pitch?
I know the sim is not the replacement for the real thing.
I would appreciate some expert knowledge on settings and procedures,Thanks Steve

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03-09-2012 07:47 PM  6 years agoPost 2
Gyronut

rrProfessor

Martinsville In.

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I'm sure other will chime in but I have been successful using neg 5 to 6 deg pitch.

Rick

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03-09-2012 07:48 PM  6 years agoPost 3
Heli 770

rrProfessor

USA.

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03-09-2012 07:50 PM  6 years agoPost 4
chris6414

rrApprentice

Sneads Ferry, NC USA

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Well, I certainly am no expert but have just began doing autos with my Hawk Sport. 550 MM mains. I use about -5-6 at the bottom in TH Hold. As I am coming down the head speed realy picks up and I find I have about 4-5 seconds worth at the the bottom. I don't have a driven tail either and it autos nice. My Ergo was leaps and bounds better due to the 700's I was swinging. The gasser will have additional weight but I imagine it would auto nicely. Even in my Hawk I don't imagine I am much over 1800 HS with the OS .32 in it. Autos stick better in the grass when your new at it. My first blacktop ones were bouncy. I was scared to death the first time I did it for real as i was testing a friends Raptor and ran it dry while climbing out of a comfined space. Wacked the rudder and brought her back and flared early and dropped rotors level. That was my first ever real auto. With someone elses bird.

Century Hawk Sport, OS .32, Futaba 7C, GY-601 9251
Predator Gasser SE G-23, Fut 3010 servos, JR gyro/servo

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03-09-2012 08:20 PM  6 years agoPost 5
S Crutchfield

rrNovice

Arkadelphia,Ar. usa

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I,m flying a Vario Acrobatic. It does not have a driven tail. Im guessing if you turn you can only use ailerons and let the tail weathervane.I've been told the tail will follow the nose.
Hmmmmm, backing up might get interesting!

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03-09-2012 08:52 PM  6 years agoPost 6
Pistol Pete

rrProfessor

Seffner, FL

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Here's a good read for all levels.

https://rc.runryder.com/t636100p1/

~~Enjoying the hobby one flight at a time~~

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03-09-2012 09:07 PM  6 years agoPost 7
Richardmid1

rrProfessor

Leeds, England

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Best thing to do is simply raise your throttle hold quite high, almost enough to hover and try an auto like that then just keep reducing the throttle hold rpm as you feel more comfortable. Just remember not to start the heli in throttle hold after you have set it high, start in normal mode using caution not to accidently hit the throttle stick.

60% of the time, it works every time!

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03-10-2012 12:01 AM  6 years agoPost 8
junkpilot

rrVeteran

Alamogordo N.M.

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Pitch setting
I fly an X-cell with a 90 size engine, Weighs around ten pounds. I have SAB full symetrical 720 blades. I set the negative at -5 degrees with the stick all the way down and +12 degrees with the stick the way up. Set your idle for a reliable idle (no need for fast idle).
Your very first auto will be perfect as will all that follow. The hang time is incredible. No need to wish you luck because it's the perfect setup!
Junkpilot

When you fly JUNK it's hard to tell when you've crashed!

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03-10-2012 12:22 AM  6 years agoPost 9
helibeli

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wales.uk

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As a matter of interest do full size helis go negative,or would that be too terrifying for the passengers?

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03-10-2012 12:30 AM  6 years agoPost 10
Twrecks600

rrKey Veteran

Round Rock, Texas

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I must be the oddball because I run the exact same pitch on throttle hold as I do in all flight modes. Linear with approxomately 12.5 degrees + and -.

I fly that way because when I'm doing inverted and tumbling autos, I want the full pitch range. Also, if I want to bring the machine down quickly, I have the full pitch range to do so. If you are running only 4 or 5 degrees, you don't have any more if you need it. If you run full linear, you have a whole lot more to play with!!

Team me

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03-10-2012 12:37 AM  6 years agoPost 11
KC36330

rrNovice

Enterprise, AL

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i too run the same pitch curve in all flight modes, anything more then -5 only increases the rate of decent. full scale helis do NOT have negative pitch, you keep the head speed by maintaining forward air speed, you don't shoot a strait down auto like you can with the models.

Morgan Fuel / JetCat / KingTech Turbines

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03-10-2012 12:45 AM  6 years agoPost 12
Thatlumox

rrApprentice

NY

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I must be the oddball because I run the exact same pitch on throttle hold as I do in all flight modes. Linear with approxomately 12.5 degrees + and -.
Same here.

"I'm a dirt torpedo!"

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03-10-2012 03:22 AM  6 years agoPost 13
MANCHA

rrVeteran

Cabo San Lucas, Baja- Mexico

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If you are not doing inverted autos, -5 is more than enough,
Specially if you are learning to !

MANCHA

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03-10-2012 01:22 PM  6 years agoPost 14
BarracudaHockey

rrMaster

Jacksonville FL

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Most full scale go to flat pitch but they have some washout built in which gives a touch of negative at the tips and a the blades have a LOT more inertia than ours.

The answer is anywhere from -2 to -5 or so depending on...
The weight of the heli
The design of the blades

There is a window between not enough and you decay head speed to fast, and where giving more just makes it drop like a home sick lawn dart without any benefit of more rotor rpm.

There's a sound they make when the blades are happy in an auto, learn what yours sounds like and thats the most efficent descent rate.

I still run a linear curve in TH so I dont have to worry about switch flipping, my helis behave the same in all flight modes. This also gives you flexability to deal with changing your landing spot, dealing with wind etc.

Andy
AMA 77227
http://www.jaxrc.com

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03-10-2012 06:54 PM  6 years agoPost 15
S Crutchfield

rrNovice

Arkadelphia,Ar. usa

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Thanks guys for the good info!

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03-11-2012 12:21 AM  6 years agoPost 16
KC36330

rrNovice

Enterprise, AL

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Most full scale go to flat pitch but they have some washout built in which gives a touch of negative at the tips
not any of the full scale we fly here at Rucker. Most won't even go as low as 5° with the collective stick in the floor, rotor speed is kept up by airspeed.

Morgan Fuel / JetCat / KingTech Turbines

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03-11-2012 12:58 AM  6 years agoPost 17
John Krebs

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Pittsburgh, PA

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I must be the oddball because I run the exact same pitch on throttle hold as I do in all flight modes. Linear with approxomately 12.5 degrees + and -.
Me too. I just give whatever negative pitch I need for the conditions and rate that I want to drop. I can understand having one or two degrees more pitch on top but I don't see why you would want to have the pitch vastly different in throttle hold.

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03-11-2012 03:44 AM  6 years agoPost 18
Twrecks600

rrKey Veteran

Round Rock, Texas

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Me too. I just give whatever negative pitch I need for the conditions and rate that I want to drop
Totally agree!! If it's windy and I want the machine to come down quickly or something, I want to know that I have the ability to do so. Also, when I'm doing inverted blade stops, you gotta have plenty of negative to stop the blades. -5 might do it but not quick enough!!

Team me

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03-11-2012 05:32 AM  6 years agoPost 19
heli-cuzz

rrElite Veteran

Pittston, Pa. USA

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I must be the oddball because I run the exact same pitch on throttle hold as I do in all flight modes. Linear with approxomately 12.5 degrees + and -.

I fly that way because when I'm doing inverted and tumbling autos, I want the full pitch range. Also, if I want to bring the machine down quickly, I have the full pitch range to do so. If you are running only 4 or 5 degrees, you don't have any more if you need it. If you run full linear, you have a whole lot more to play with!!
+1

Fury 55 NIB Furion6 CGY750 fbl helicopter-Frenzy CGY750 fbl nitro-Frenzy fbl NOBAR90

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03-11-2012 06:05 AM  6 years agoPost 20
MXRACERX43

rrApprentice

Hazleton,PA USA

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[quote]I must be the oddball because I run the exact same pitch on throttle hold as I do in all flight modes. Linear with approxomately 12.5 degrees + and -.

I fly that way because when I'm doing inverted and tumbling autos, I want the full pitch range. Also, if I want to bring the machine down quickly, I have the full pitch range to do so. If you are running only 4 or 5 degrees, you don't have any more if you need it. If you run full linear, you have a whole lot more to play with!!
+1

Thats fine once you have autos down and you need a linear curve when doing aerobatic autos. But keep in mind the OP is looking at doing auto's for the first time. Inthis situation I would definately limit hi -pitch value so he cant bury the stick and add too much -.

Team Miniature Aircraft~Team GensAce

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HomeAircraftHelicopterMain Discussion › Autorotation- what is most efficient negative pitch angle?
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