manual hydraulic system for aircraft

[telecom]

Hi,
I want to be able to turn hydraulic motor CW or CCW to drive ailerons of a small airplane by the means of hydraulic cylinders.
How do i make a small oil tank to compensate for oil expansion/contraction?
Do you know any similar application?
I looked at the boat helm steering but it is too expensive and optimized for boats.
I would like to use standard hydraulic components.
Alex

[Doug Hanson]

Your on the right track with helm controls. The only thing I can suggest is that you look at a schematic of a helm control and and then locate off the shelf components that will accomplish the same thing. I'm a little nervous to make suggestions for aviation applications.

[telecom]

Thank you for your reply, but I wasn't able to find any schematics.
To me it looks very much like a hydraulic motor where steering wheel is attached to the shaft.
I'm thinking of putting in the curcuit something like spring loaded DIY acumulator to compensate for termal
expansion/contraction.
The whole subject is purely hypotetical and not going to be used in actual aircraft.
Alex

[Doug Hanson]

Give this link a try: http://forums.hydraulicspneumatics.com/ ... #360105535

[telecom]

Thank you!
I red it.
What I'm thinking of, rather then to put a relief valve, to install a DIY spring-loaded accumulator,
aka a cyliner with several compression springs, to create some pressure in a system.
This will work as an oil tank as well.
Drawback is, that working pressure will be limited to the pressure created within this DIY device,
probably around 200 psi.
Is this something new or its already in use?
Thank you very much for your kind help.
Alex

[Doug Hanson]

Spring loaded accumulators do exist, there not super common. You still need a pump to charge up your accumulator, and now have to have a uni directional pump, as opposed to the helm control which is a biderectional pump. So in using a uni-directional pump, you now need to add a control valve.

You could stay with the bi-directional helm control system and use a sealed reservoir that has an expansion chamber (kind of like a rubber belows.) There is a company that build expansion chambers for reservoirs but I can't remember who.

[telecom]

Doug,
I could create pressure in a system manually, when I tighten up compression springs of the accumulator,
that was my idea anyway.
"You could stay with the bi-directional helm control system and use a sealed reservoir that has an expansion chamber (kind of like a rubber belows.) There is a company that build expansion chambers for reservoirs but I can't remember who."
This is exactly what is needed.
Thank you again.
Alex

[Doug Hanson]

I might not be understanding what your trying to do here. You can store an amount of initial energy in the accumulator, but as this potential energy is consumed, what is restoring more energy. You only have a given amount of fluid available (differential volume of the accumulator) and the force available to the actuator will decrease as the oil is consumed in the system. Where is your return oil going?