RE: Airplane rudder gyro  
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All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> RE: Airplane rudder gyro
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RE: Airplane rudder gyro - 8/28/2007 12:39:39 AM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline
quote:

ORIGINAL: hlhamner

Big Bird,

If you don't move the rudder left and then right to let the gyro re-center in HH mode for some reason it cuts the gain way down - almost to the point of being worthless.

Try it on the ground and you'll see that when you go back to HH mode without moving the rudder the gyro response to movement is dampened significantly. At least that's the way my GY401 works.

Hank

Hank, I just made some careful observations and you are correct. The rudder movement is about half unless you move the rudder stick back and forth a couple of times. I will be wiggling the rudder. Thanks

_____________________________

Ken
WACO Brotherhood #70

(in reply to hlhamner)
       Post #: 76

RE: Airplane rudder gyro - 8/28/2007 2:44:51 AM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline 		I have the GY401 mounted in the Jungie. I put it in the clear near the CG. The pilot will be able to keep an eye on it and let me know if he sees it doing anything wrong. I'll probably test it this weekend.

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Ken
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       Post #: 77

RE: Airplane rudder gyro - 8/28/2007 12:44:14 PM   
Howard


 

Posts: 210
Joined: 9/12/2002
From: Viera, FL, USA
Status: offline 		Gentlemen:

First - this is the best discussion I have read about using airplane gyros for take off, thanks for sharing your experiences. Now that I know that using HH is very helpful I trying to decide on which gyro to purchase. I use five cell (6 volt) airborne batteries and prefer not to have to add additional stuff, such as regulators, (Keep It Simple axiom) and the 401 data on Tower says you have to use 4.8 volts or if it is greater than six volts to use a regulator. When the five cell (NIMH/NICD) comes off the charger it is greater then six volts. Is this something I have to be concerned about. Everyone seems to be having real success with the Futaba GY401 but I really don't want to add a regulator or to go back to four cell flight packs.

If the 401 will not work then I was looking at the Ikarus Profi gyro (item 720613) that seems to be very similar to the Futaba but is more forgiving over a wider range of volts. When I checked yesterday the cost, including shipping, was going to be $87. I should add that my only plan for the gyro is for takeoff and maybe to try HH during loops - I am not into 3D and such.

Once again, thanks for providing some very helpful information about using gyros for take off - any help on my voltage question would be appreciated.

Howard


(in reply to Big_Bird)
       Post #: 78

RE: Airplane rudder gyro - 8/28/2007 1:17:42 PM   
hlhamner


 

Posts: 31
Joined: 7/18/2006
From: Flower Mound, TX, USA
Status: offline 		Howard,

I tried a 5 cell NiMh pack without a 6 v regulator and it messes up the gyro until the pack settles. I suggest using a $29 regulator, a 4 cell pack or discharge your 5 cell pack to 6 volts before using. Normally when you switch between HH and normal mode the LED on the GYRO goes from on to off. When over 6 volts it flickers in both modes. I didn't wait to see how it would work because I was afraid I'd ruin the gyro so I unplugged the 5 cell. I now us a regulator that probably weighs 1/4 oz.

Hank

(in reply to Howard)
       Post #: 79

RE: Airplane rudder gyro - 8/28/2007 3:10:47 PM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline 		Howard, if you want to use a GY401 on a 6 volt system then this might be your simple solution. You can install two diodes in series with the positive lead going to the gyro. These diodes are rated at 1 amp and reduce the voltage by approximately 1.4 volts total. Otherwise use a 5 volt regulator or another brand of gyro.

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Ken
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       Post #: 80

RE: Airplane rudder gyro - 8/28/2007 3:32:49 PM   
hlhamner


 

Posts: 31
Joined: 7/18/2006
From: Flower Mound, TX, USA
Status: offline 		If you used diodes or a regulator make sure the diodes or regulator is connected from the switch to the receiver and not from the battery to the switch if you use an external charge cord.

The biggest difference, other than cost, between using a regulator and diodes to drop the voltage is that when the 5 cell pack gets to 6 volts the receiver only gets 6 - 1.4 or 4.6 volts. The regulator would pass through 6 volts if a 6 volt regulator or 5 volts if a 5 volt regulator. The regulator will always pass through the lower of battery or regulator voltage.


Hank

(in reply to Big_Bird)
       Post #: 81

RE: Airplane rudder gyro - 8/28/2007 4:32:49 PM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline 		Hank,

You may have misunderstood what I was talking about. I intended for the diodes to only be between the receiver and the gyro/rudder servo. There is no reason to take the receiver off of the 6 volt battery system. The diodes can be soldered into the red wire of a short extension lead between the receiver and the gyro. That way there is no modification to the lead that is on the gyro. Of course when you do this you reduce the voltage to the rudder servo as well. Actually one diode might work giving a 0.7 volt drop.

If one is to put a 5 volt regulator between the battery switch and the receiver then this is defeating the use of a 6 volt NiMH battery pack. In that case just use a 4 cell pack.

My best recommendation is to use a GY401 with a 4 cell pack or select another gyro which will accept a 5 cell pack. My fleet consists of all gassers and I use 4 cell packs exclusively even in the 300S with the Brison 6.4 twin.

_____________________________

Ken
WACO Brotherhood #70

(in reply to hlhamner)
       Post #: 82

RE: Airplane rudder gyro - 8/28/2007 4:45:29 PM   
hlhamner


 

Posts: 31
Joined: 7/18/2006
From: Flower Mound, TX, USA
Status: offline 		Ken,

You get more torque from 6 volts if the servos will handle it. I use regulators because I don't want the jitters when I stick a fully charged 5 cell pack in that tops at 7.5 volts and regulate it to 6 volts. I use 5 cells for the redundancy along with a regulator. If a cell fails in a 4 pack you have about 3.6 volts and with a 5 cell 4.8. It does add a little weight. Every month or so I cycle my packs just to make sure my capacity is not degrading - if so I replace the pack.

In my lighter planes I use a 7.4 volt Li Poly 1,500 mAh pack regulated to 6 volts just to save weight.

If you don't need to torque use a 4 cell pack and that solves the problem.

Thanks for the information.

Hank

(in reply to Big_Bird)
       Post #: 83

RE: Airplane rudder gyro - 8/28/2007 5:23:04 PM   
Flyfast1


 

Posts: 367
Joined: 9/25/2005
From: Livermore, CA, USA
Status: online 		Hi Howard,

Welcome to the discussion. Is the Ikarus Profi gyro controllable remotely from the transmitter? I think that several of us have found it helpful to be able to change the gyro mode (or turn it off) from the transmitter, so this might be a good feature to have.

-Ed B.



quote:

ORIGINAL: Howard

Gentlemen:

First - this is the best discussion I have read about using airplane gyros for take off, thanks for sharing your experiences. Now that I know that using HH is very helpful I trying to decide on which gyro to purchase. I use five cell (6 volt) airborne batteries and prefer not to have to add additional stuff, such as regulators, (Keep It Simple axiom) and the 401 data on Tower says you have to use 4.8 volts or if it is greater than six volts to use a regulator. When the five cell (NIMH/NICD) comes off the charger it is greater then six volts. Is this something I have to be concerned about. Everyone seems to be having real success with the Futaba GY401 but I really don't want to add a regulator or to go back to four cell flight packs.

If the 401 will not work then I was looking at the Ikarus Profi gyro (item 720613) that seems to be very similar to the Futaba but is more forgiving over a wider range of volts. When I checked yesterday the cost, including shipping, was going to be $87. I should add that my only plan for the gyro is for takeoff and maybe to try HH during loops - I am not into 3D and such.

Once again, thanks for providing some very helpful information about using gyros for take off - any help on my voltage question would be appreciated.

Howard




(in reply to Howard)
       Post #: 84

RE: Airplane rudder gyro - 8/28/2007 6:02:47 PM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline 		Ed here is a link where you can find a description of the Ikarus gyro.

http://www.hobby-lobby.com/gyros.htm


Here you can see how the 401 and Ikarus look inside.

http://www.mh.ttu.ee/risto/rc/electronics/radio/gyro.htm


_____________________________

Ken
WACO Brotherhood #70

(in reply to Flyfast1)
       Post #: 85

RE: Airplane rudder gyro - 8/28/2007 7:12:02 PM   
BarracudaHockey



Posts: 10590
Joined: 7/13/2003
From: Orange Park, FL, USA
Status: online 		The gyro will take 6v, the tail rotor servos wont, not at high frame rate in any case. We use .7v step downs to the servos with 6 volt systems all the time in helis, though the majority of us with higher end helis run 8 volt lithum packs with regulators.

As for dual rates its important to understand the concept that the end points on the rudder channel have no effect on total servo throw, thats set by the limit on the gyro. In helicopters that end point sets the rate at which the nose will turn. So if you reduce the end point the gyro will command a yaw (piroette) at a given rate, if the winds blowing this will allow the gyro more throw to maintain that piro rate.

I suspect but dont know for sure without testing, that low rate on the rudder would have the same effect on an airplane, less rudder throw for less turn rate but it may not be immediately obvious on the bench I would experement with say 10 percent changes at a time.

As for the gain, 100 percent end point is 100 percent gain, going farther does nothing.

If you have the 9C super LMK and I'll tell you how to use the GYRO SENS screen to your best advantage and that way theres no question what gain you are running as its WYSIWYG when properly setup.

< Message edited by BarracudaHockey -- 8/28/2007 7:13:01 PM >

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       Post #: 86

RE: Airplane rudder gyro - 8/29/2007 10:25:25 AM   
Howard


 

Posts: 210
Joined: 9/12/2002
From: Viera, FL, USA
Status: offline 		BarracudaHockey, Big Bird, Flyfast 1 and hlhammer,

Thanks for the feedback - based on the information you provided I believe I have several options open which include, installating a four cell flight battery, voltage regulator, diodes between the receiver and gyro, or use the Ikarus Profi gyro. The Ikarus gyro does have remote sensitivity/switching and after reading the mfg instructions that you provided it seems to be me that it should work.

IMHO using a five cell flight pack was the best and least expensive servo response improvement I have made - almost like buying all new upgraded servos for no additional cost. That is why I hate to go back to a four cell flight pack. The plan is for the gyro experiment to go into a Great Planes RV 4 and just for general experiment. One of my flying compadres has a CG cub that he struggles with on the take off track and I believe a HH gyro would resolve his problem.

Any additional comments or thoughts would be helpful and appreciated.

Howard


(in reply to BarracudaHockey)
       Post #: 87

<
RE: Airplane rudder gyro - 8/29/2007 2:44:59 PM   
Big_Bird



Posts: 3183
Joined: 12/18/2001
From: Arlington, TX, USA
Status: offline 		Howard,

Glad you dropped in here. I think almost any Golden Age or WWI plane which can be squirrelly on takeoff would benefit from using a rudder gyro. The specs on the Ikarus gyro look pretty good. Let us know which way you decide to go.

_____________________________

Ken
WACO Brotherhood #70

(in reply to Howard)