Boo2

Hi,

I am building a plane and it is the first I have built with operating gear doors. I want to use air cylinders to operate the doors but I am unsure how to pick the stroke size ?

To look realistic in operation the open gear doors must open to a fixed position. I can obviously mount the cylinders so the when fully extended the gear doors are correct. But if I do this then when the cylinders are closed, unless I manage to find some with the right length to sub-millimeter accuracy, the entire force of the cylinders will be stressing the doors and their hinges. Is this the normal way of going about it ? I have no idea how much force one of these cylinders is capable of providing and I'm interested to hear other peoples opinions about how to do gear doors with air cylinders.

Many thanks,

Boo

BirdofpraY

My Feedback: (31)

Boo, All you have to do is use a piece of copper tubing and cut it to proper length and size, solder it on or glue it over the exesting rod of the cylinder so that when you retract the doors it stops at the copper tubing. This will stop the rod from adding any pressure on your doors and hinges. You can paint the copper tubing to make it look scale.

Modelman

My Feedback: (7)

You can also slip a standard wheel-collar (1/16"?, 3/32"?) onto the shaft of a slightly longer-than-required air cylinder. Set the cylinder, with the shaft fully extended, to the correct door-open angle - and with a little trial-and-error, you can tighten the wheel-collar in the "Just-right" spot against the top of the cylinder body - preventing the shaft from retracting any further. I've done this numerous times with great success!

HTH,

C.

MaJ. Woody

My Feedback: (28)

Tam told me a trick for this.........slide some small fuel tubing (nitro stuff) over the shaft on the air cylinder. Then when the doors close, there is no pressure on them. The wheel collar idea is great but you run the risk of putting a burr on the shaft and that can cause the cylinder to leak if you change the location of the wheel collar.
Dom

causeitflies

And the fuel line gives a shock obsorber effect.

Boo2

Thanks to all for the ideas. I think I will try the fuel tubing first because the shock-absorbtion sounds useful. I have a lathe so I can make stops up if there are problems with fuel tube but I admit that the idea of a stop on the shaft just never occurred to me, simple as it is [sm=red_smile.gif]

Thanks again,

Boo