View Full Version : Trim System Linear Servos
03-19-2004, 12:03 PM
Can anyone point me towards an online source for linear servo motors being used to control trim systems on gyros?
Ideally I'd like something reasonably priced (I'm thinking $50 or less each), compact, lightweight, and water resistant. Am I asking too much? I need two of them... one for pitch and one for roll.
I see A/C-Spruce sells Ray Allen servos, but they cost around $120 each, and they sure don't look water resistant (they don't say). See http://www.aircraftspruce.com/catalog/elpages/ractrimservos.php for more information.
What kind of motion range would you think would be needed to adjust the trim on a lightweight gyro (my GyroBee)? One inch?
Can anyone who designed and added an electric trim system to their gyro give me any pointers?
03-19-2004, 12:36 PM
Check with Air Command they have one on their Geen Machine two place trainer.
03-19-2004, 12:40 PM
John, would you plae let me know what you find out. I am in the need for a supply of these for Firebird. Thanks.
With the Raf "wind the thread" trim adjustment, there is available approx 2 1/4" adjustment. This is not quite enough sometimes with the variety of weight scenerios available with the Raf. This is acting in two springs with the Raf, so with one spring it would require double that.
Rotor blade design can influence the amount of trim spring pressure required. Also the strength of the spring itself. Ken L, remember great old Ken? upgraded the Raf springs to ones that were a little stronger. Ken said that then gave him the range he needed.
Go to this web page for a list of linear actuator manufacturers:
I don't know which ones are used on gyroplanes, but some of them "look" a lot like the one I have on my Air Command:
My actuator has a range of about 4", but I don't know how much of that is actually needed.
Let us know what you find.
03-19-2004, 01:07 PM
I believe that the ones Air Command has was made for a hospital bed? I bought one for over $200.00 from them for my tandem.
I use a throttle venier off of a semi tracter truck for the GADGET, it works great but is manuel.
03-19-2004, 08:36 PM
Take a look at ebay. A search for Linear Actuator brought back 43 results. While it may take awhile to find the perfect fit, you'll probably pay alot less.
I'm using Air Command's trim kit on my single place AC, which is centerline thrust. I'm flying a 503 with auxiliary fuel tanks, and I use every bit of the 4" of travel going from full load to less than half load.
It's a nice system, but extremely pricey nowadays( I've had mine for three years). Have done a search on the Internet for this brand, and keep coming up with nothing.
Once you have a system like this, you'll never go back to a manual setup. It's so nice to just flip a switch to set my trim for whatever speed I want to fly at, and never deal with any stick pressure.
Good luck in your search.
03-21-2004, 04:19 PM
Can anyone post some pics on these linear trim systems on a gyo??
This is a picture of my linear servo on my Air Command. I control it with a momentary-on--off--momentary-on switch. You have to play with different spring setups to get the proper range of control for your machine. Took me about three tries to get the right springs.
03-28-2004, 03:31 AM
These actuators are mostly Linaks, see www.linak.com
03-28-2004, 04:04 AM
Thanks for the pic John I understand how they are being used now.
03-28-2004, 04:06 AM
Thanks Mark for your pic too, Glad that we have people i here that can help so much with understanding the systems
03-28-2004, 04:08 AM
Next question, does this trim accuator also trim the yaw on the rotor??
03-30-2004, 05:40 PM
I am pretty sure RFD (Dominator) sells these.
Give Ernie a call he can get just about any part for a gyro.
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