Suggestions for trim systems

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A lot of designers are installing linear actuators for their trim systems. Any suggestions on these and other solutions? What is the estimation of force needed to remove stick pressures felt by the pilot in a "typical" tandem two place machine?
 

Sv.grainne

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I have some info on the Tango, will post tomorrow, unless I can find photo without moving! Found the file but have to edit size tomorrow, to large for forum.
 

thomasant

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The amount of force required is usually anywhere from 40 to 60 lbs.

We have two Tangos in our club. According to the specs on their linear actuators, the force exerted in pull is 1200 N or 270 lbs. This is quite excessive to manually override if something happens to the actuator. We actually witnessed this happen during a take off when a pilot accidentally used max force and was unable to override and push cyclic forward; ended up destroying his blades when his nose wheel whipped up during the take off run.

Try this from Amazon for $63.00:

SOViK 4 inch Stroke Micro Linear Actuator, 12V DC Built in Limit Switch, 55lbs Maximum Lift Includes Mounting Brackets
 

Sv.grainne

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I would not use the Sovik actuator, travels at 1" per second. For trim I would want something in the order of .25" per second. Leaving now but have researched some info on lower pull actuators. Will try to post again this evening.
 

thomasant

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The Sovik was recommended to me by Vance, and I would rather rely on the judgement of someone who uses it.
 

Vance

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The amount of force required is usually anywhere from 40 to 60 lbs.

We have two Tangos in our club. According to the specs on their linear actuators, the force exerted in pull is 1200 N or 270 lbs. This is quite excessive to manually override if something happens to the actuator. We actually witnessed this happen during a take off when a pilot accidentally used max force and was unable to override and push cyclic forward; ended up destroying his blades when his nose wheel whipped up during the take off run.

Try this from Amazon for $63.00:

SOViK 4 inch Stroke Micro Linear Actuator, 12V DC Built in Limit Switch, 55lbs Maximum Lift Includes Mounting Brackets
Most gyroplane trim systems with a linear actuator that I am familiar with have a spring in the system.

Part of the allure of pneumatic systems is pneumatic cylinders are a progressive spring at appropriate pressures.

I have not flown a gyroplane with a trim system that I could not overcome with pressure on the cyclic. I have not flown a Tango.

I have had two different linear actuator trim systems in The Predator fail and it was a nonevent both times.
 

Vance

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I would not use the Sovik actuator, travels at 1" per second. For trim I would want something in the order of .25" per second. Leaving now but have researched some info on lower pull actuators. Will try to post again this evening.
I have found a trim system with a slow linear actuator annoying to use and difficult for my clients to learn on.

The leverage has a lot to do with speed and force required.

I am not a trim enthusiast and feel that consistent cyclic pressures is easier to learn particularly on takeoff.

I train in a two place tandem and the trim is very different between a hundred thirty pound client in the front seat and a two hundred fifty pound client in the front seat.
 

thomasant

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I had a failure once in my old tandem Air Command, and I too was able to manually override it. In the AR1, I seldom had to use the trim unless I was flying with someone over 200 lbs. I do not use trim on take off, only in cruise. Moreover, I have not had any issues with a fast trim and prefer the quick response. I am now setting my trim with the one I posted. It's speed seems adequate to me.

If Sv.grainne can find some other actuators, that will be great.
 
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Hueychief

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I would not use the Sovik actuator, travels at 1" per second. For trim I would want something in the order of .25" per second. Leaving now but have researched some info on lower pull actuators. Will try to post again this evening.
The 1"/sec actuator is the SOVIK 22lb. actuator.
I am using the SOVIK 4" 55lb. actuator on my build which is 8/25"/sec travel IAW manufacturer specs.
 
Joined
Jun 7, 2019
Messages
24
Location
Bryan, Texas
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Cessna 140, Stinson 108-1, Culver V, Parsons Trainer
Total Flight Time
1000 hours
The amount of force required is usually anywhere from 40 to 60 lbs.

We have two Tangos in our club. According to the specs on their linear actuators, the force exerted in pull is 1200 N or 270 lbs. This is quite excessive to manually override if something happens to the actuator. We actually witnessed this happen during a take off when a pilot accidentally used max force and was unable to override and push cyclic forward; ended up destroying his blades when his nose wheel whipped up during the take off run.

Try this from Amazon for $63.00:

SOViK 4 inch Stroke Micro Linear Actuator, 12V DC Built in Limit Switch, 55lbs Maximum Lift Includes Mounting Brackets
Thank you all for the input. I am wondering with the faster actuator, that being able to 'bump' the trim with a momentary switch is how the user is able to control the trim with some finesse. I expect the coolie hat type switch on the control stick would be mandatory. Perhaps one on the throttle quadrant would be acceptable as well. What are your thoughts?
 

thomasant

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Thank you all for the input. I am wondering with the faster actuator, that being able to 'bump' the trim with a momentary switch is how the user is able to control the trim with some finesse. I expect the coolie hat type switch on the control stick would be mandatory. Perhaps one on the throttle quadrant would be acceptable as well. What are your thoughts?
Welcome. Yes, there is a HAT switch on the cyclic in the AR1. Works well. The speed of the actuator is not the issue, it is the force required to override if there is a powerful actuator. The issue with a very slow actuator is that the response time for the effect is longer. But it is not critical.

I flew the Lama helicopters for many years. Turbine engine with hydraulic servo assist for the controls. We never had a trim system in it.
 

Sv.grainne

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I am looking at Firgelli actuators.

Flew in training yesterday and once airborne used trim control at cruise speed in straight and level flight. With the spring setup between the actuator and rotor head no issue overcoming actuator in a failure situation, IMO.

Bobby
 
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