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HelicopterBeginners Corner › Gyro heading hold vs rate. and servos.
09-12-2007 02:18 PM  10 years agoPost 1
CUJO

rrApprentice

San Angelo, TX

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I know what a regular heading hold gyro does but what does a "rate" gyro do? (as per RcHeli magazine, they only talked about the heading hold).

And why the big difference between the Futaba 69 jobbers to the 300 dollar ones with digital servos?

Being a beginner though RcHeli recommends getting the most expensive ones you can get, but for a guy that wants to just do scale and perform nothing more than maybe a hammerhead stall is going allout on servos really going to make that much of a difference?

On radios too, I want one that will do my heli and my glider and was just thinking of getting one of the 2.4 Futaba 6channels as I've never had the need for more than 4 except the glider will have an eletric engine on it spoilers, and flaps.

And what exactly does a govenor do for heli flights? I know what a governor does in principal but how is it applied to heli?

Ok, enough questions for now. Thanks in advance.

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09-12-2007 02:53 PM  10 years agoPost 2
pH7

rrKey Veteran

Sterling Heights, MI - USA

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With HH, if there is wind coming from the side of the heli, with no rudder input it will still maintain the same heading. In rate mode, with no rudder input, the heli will pivot until it faces into the wind. There are a lot of implications to flying style, but this describes the essential difference.

I have no idea what a "Futaba 69 jobber" is, but the Futaba 401 gyro with a 9254 servo is great bang for the buck and more than sufficient for a beginner.

Six channels is bare minimum for a heli: throttle, rudder, elevator, aileron, gyro sensitivity, main rotor pitch. If you use a governor, most will need another channel, meaning a 7th channel is needed.

A governor monitors the head speed (main rotor RPM) and tweaks the throttle to maintain a constant speed. If you have someone to help set up your throttle and pitch curves, you can get along without a governor.

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09-12-2007 03:18 PM  10 years agoPost 3
BarracudaHockey

rrMaster

Jacksonville FL

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It depends on where you aspire to in the hobby. If a Trex450 is the best you are going to do then you can get by fine with a 6 channel radio.

If you want to fly nitro with a good gyro and governor then your MINIMUM purchase should be a 7 channel like the 7C or DX7

If you want nitro AND scale then you should be looking at a 9 channel because eventually you will want all the basics plus retracts or lights or whatever.

Buy the best radio system you can afford for your current and projected needs or you will just end up haveing to sell what you bought for 50 percent of what you paid for it and buying another radio.

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

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09-12-2007 07:12 PM  10 years agoPost 4
CUJO

rrApprentice

San Angelo, TX

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The 69jobber was just a reference to Futabas 69dollar gyro, I 'm not sure of the name or model but just that that was the cheapest. When I flew my Mini-Boy eons ago gyros weren't the needed item they are now I guess.

Do alot of people use govenors or is it just easier to get better performance out of your heli that way? Or is it like in a real heli where you put your rotor rpm up to a level then just use the collective to work the blades? Still kinda confused about it all.

Scale wise I was thinking about a H500 so I wouldn't need retracts but the lights seem cool, but really not needed. Couldn't those be toggled somehow anyways?

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09-12-2007 07:16 PM  10 years agoPost 5
BarracudaHockey

rrMaster

Jacksonville FL

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People didnt fly backwards at 100 mph back then, we were lucky to get them off the ground.

Yes it makes it just like a full scale. Its not "needed" unless you are doing 3d and loading and unloading the blades, then it helps from over speeding and to some extent bogging the motor.

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

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09-12-2007 08:25 PM  10 years agoPost 6
CUJO

rrApprentice

San Angelo, TX

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So with a govenor switch you can set the rpms, build the rpms for takeoff, then just switch over to pure collective while the engine stays a constant rpm?

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09-12-2007 08:39 PM  10 years agoPost 7
DS 8717

rrProfessor

Here wishing i was somewhere else

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Governors are the next best thing ever invented after heading hold gyro's...........

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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09-13-2007 01:28 AM  10 years agoPost 8
crofty

rrApprentice

Phoenix, AZ - USA

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Related Question

For Auto's with the throttle hold engaged should the gyro be set up to switch from HH to rate mode? I believe it is a good idea to weather vane and use the wind. Am I right?

(This is not how I am configured now but since I have a Trex 450 that has all the flight capabilities of a house brick without it's motor it has yet to be an issue.)

I have nerves of steel but thumbs of jelly!

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09-13-2007 01:39 AM  10 years agoPost 9
DS 8717

rrProfessor

Here wishing i was somewhere else

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I have mine in heading hold with more gain for throttle hold,the gyro can hold the tail better than you can.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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09-13-2007 02:55 AM  10 years agoPost 10
mikeflyz

rrApprentice

Westlake Village, CA

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For Auto's with the throttle hold engaged should the gyro be set up to switch from HH to rate mode?
That used to be the procedure with non-driven tails. With driven tails, keep the heading hold on. However, I see some validity with that in the little T-Rex, but haven't tried it.
Do alot of people use govenors or is it just easier to get better performance out of your heli that way? Or is it like in a real heli where you put your rotor rpm up to a level then just use the collective to work the blades?
The GV-1 still takes the throttle input. The governor acts as a trimming device. Other governors are more accurately "overspeed" governors, that only reduce the throttle when the RPM is over the set amount. They speed up the setup by not having to fine-tune the throttle curves and also act to help maintain RPM with high cyclic deflections. You can build cyclic-to-throttle mixes in the radio for that purpose, but risk overdriving the throttle servo beyond the full-power position and risk the link coming off and ruining your day. Also, it won't do anything about bogging the head if you're out of power and have too much pitch.

A real helicopter's collective also increases/decreases engine power along with blade pitch. For turbines, it uses a droop compensator, and for pistons, it uses a throttle correlator. Governors act on top of them to keep the RPMs constant.

Yes you can use the governor to switch to multiple RPMs. You need an additional channel on your radio to do this (CH 7 or 8 usually).

Mike
MA Fury Extreme, JetCopter SX

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09-13-2007 04:19 AM  10 years agoPost 11
oldboldpilot

rrKey Veteran

Southern California

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CUJO,

A rate gyro tries to keep the yaw rate zero. The error in this kind of control loop is yaw angle - and every time the main rotor changes speed or pitch, there will be another yaw angle error.

Tough work load taking off and landing, as changes in main rotor torque will result in fairly large rates and rate changes. If you want the nose kept still, you will have to do that yourself in rate mode.

One good thing is turns tend to be "coordinated." Bank and pull for a left turn, and the nose comes around, too.

Heading hold tries to keep the nose pointed where you last commanded it. That is, you apply rudder command until you see what you like for a heading, then you release the rudder input, and the gyro tries to keep the nose pointed there.

The expensive HH gyros do this very well, indeed. They provide a consistent/repeatable yaw rate for a given control input, which starts NOW, and when you zero the control input, the tail stops NOW. They do this in any flight attitude/airspeed. You fly a coordinated turn by inputting the rudder needed to keep the nose into the turn. An example of a spectacular high-end gyro/servo combo is the JR7000/JR8900. The Futaba high-ender is the 611 gyro and that comes with a recommended Futaba servo as well.

As to governors, for the kind of flying you describe, you don't need one. You will set up your pitch and throttle curves to suit your model, and that's all you need.

As to radios, if you want no more than 6 channels, and you also want 2.4 Ghz, you have a choice between a Futaba 6-channel or a Spectrum 7-channel. But you might catch a used higher-end 72 Mhz set for the same $$$ - something to think about.

Helis are Man's Defiance of the Laws of Nature - OCHC

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