Retract question - problem SOLVED !
 

I've got my main gear "T"ed together from a Robart variable rate valve. The Right gear always goes up (and down) before the left one....there is probably a 5 -6 second delay between the two. They both work reliably every time, but I'd like them to go up and down more or less together. I thought maybe the left was was a bit tighter, but I have cycled them probably 50 times now, and no change in that behavior.

Any suggestions?

RE: Retract question
 

Are the airlines of equal lengths?

RE: Retract question
 

Take the lines from the "T" to the retracts and switch them. See if the other side moves slower. This way you will know if it is the retracts or another problem.

I had a problem with my jet with the brakes not working, bought a new brake valve, and still no brakes, here it was the metal "T" in the brake lines that failed.

Mark

RE: Retract question
 

Thanks guys...the airlines are equal length. I'll go and switch them and see if that makes a difference..

RE: Retract question
 

Probably one retract is a little tighter (piston & seal to cylinder wall) than the other. One operates with less pressure & volume of air, once it has stopped moving the air has nowhere else to go but to the other retract which then operates when it recieves enough pressure/volume. I have a set, not Robart although I do use the Robart valve, which does the same but only on the down stroke. I think this one may be a little tighter machanically. Perhaps if you open up the valve a bit you can minimise the problem. I would not worry about it, some scale flyers spend a lot of time & money getting one leg to follow the other!. - John.

RE: Retract question
 

Nony,
If that is the 16, I had a similar problem. Turned out to be the retract units themselves. The three screws per side that sandwiches the trunion into place I found on one to be too tight. A little less pressure solved the problem. I just backed the screws out slightly and then loctited so they don't move. This relieved the pressure on the trunion making it move more freely.
Mark

RE: Retract question
 

The static friction is higher in one. You may try adding a drop of silcone oil into the slower cylinder. This may help.

RE: Retract question
 

Thanks for all the suggestions guys... BC, yes it is the F-16, and you may have something there.

Boomerang you described what is happening exactly. I tried running it up to 110 psi but it did not make much difference...

RE: Retract question
 

Most full scale aircraft gear don't go up or down at the same time. And most scale guys try to emulate this. If your gear are going up and down OK.............50 cycles you said? Leave them alone.

RE: Retract question
 

On full scale jets the main gear always go up at the same time. The older wargird type aircraft had these issues because of smaller hydraulic pumps not being able to keep up.

If one main hangs down during retraction on a full scale F-16, the pilot will have a fit keeping the nose straight during departure.

RE: Retract question
 

Yeah I can see it being a desireable trait on say, a B-17.....but not on the electric jet!!

RE: Retract question
 

Thanks for all the suggestions guys. I tried most of them, with some changes noted. However Blackcloud hit the nail on the head. The one retract was a bit too tight. When I loosened off the cross bracing screws, it freed right up.

RE: Retract question
 

that is what this forum should be, A bunch of jet guys helping each other out.

Nony, glad you got the problem fixed


Mark

RE: Retract question
 

Exactly !!! :)

RE: Retract question
 

What? you mean with my luck I actually gave you correct information? LOL:D
Glad you got it working, and the Robart variable valve makes it much nicer than the slamming of the plain on/off valve.
BC

RE: Retract question
 

heh heh...luck of the draw, I guess :D:D