jetjohn

Question for all out there,

Can you use one door cylinder for two gear doors?

Or do you have to use one for each door?

I am asking this question because I have come up with a novel solution for doors which are in line with each other,see photo attached.
My question is , Are there any reasons why this should not be used. Or can you suggest an easy method of operation.

The idea is a simple rod between the two hinges on each door and a single cylinder or two cylinders one at each end,fixed to the rods but allowed to pivot on the rods. The photo makes the idea clear. Single cylinder shown.
I thought this would help by excerting an equal pull on each hinge.
In fact an equal pull on all four hinges at the same time. Which should stop distorted door closing?
Opinions please.

Thank you,
John C

mr_matt

My Feedback: (10)

Check the geometry to make sure there is clearance for the cylinder and the ball link in the "doors down" position. Looks like you are going to need to shorten the ball link substantially, nothing wrong with that. I would use a snap on ball link, it is just easier to set up.

Also, the doors will likely open and close at different rates, in as much as the friction on the hinges will vary. I would suspect that one door will activate before the other, so you need to make sure the "door open" position has a positive stop and will not be damaged when the full force of the cylinder is trying to open the other one up, vice versa with closing.

EDIT and make sure the "door open" hose will clear the starboard wheel when it is in the well.

ByLoudDesign

I let the LG retracts lift the doors, the spring makes sure it deployes when the retracts atart down. The nuts at the top control how far they drop. In the case of this P-3 they don't go all the way to 90° open, If I remember is 70°.

Gordon Mc

My Feedback: (11)

John - that's an interesting question, and I like to see people thinking 'outside the box' like this.

Aside from Matt's concern about clearance, I would just say that I think you may get some noticeably asymmetric behaviour. The way that the airlines connect would seem to suggest that there will be more 'drag' (can't think of a better term right now) on one side than the other ; as a result you may see one door opening differently than the other.

Airforce7

My Feedback: (31)

John,

Couple of comments, the idea and design looks great. How do you plan to secure the rods? Maybe a bead of glue on either side of the hinges could work. Also, the hinges suck and I'm sure you know that. So with that said, you might want to make it easier to replace the left side door hinges in case of fatigue or a mishap.

Ken

lov2flyrc

My Feedback: (24)

I tried this method several years ago on a Skymaster F15 and was not pleased with the results but, it has been too long for me to remember why I abandoned the method. Think it had something to do with the doors tending to sway (you could push the doors left right) in the down position which created other issues.
Curious to see if you can work it out on this airframe....
Todd

Vincent

My Feedback: (61)

I would question if the one cylinder will have enough power to open and close both doors under wind loading??
V..

jetnuno

Hi

This is a good idea. most of all, to stop the jamming on doors during opening and closing. Even if you use only one cilinder for each door, if you link it in the middle of the piano wire, the force is better distributed along the door. This might work very well for big doors linked with a cilinder only in one end.

Besides the possible inconvinience of the closing speed and travel end point might be diferent, as stated above, you will also need a double stroke cilinder to get the same travel in both doors.

Another possible downside is that the opening/closing force is cut in half (1 clinder for 2 doors), so more pressure might be needed. Of course, this ratio is valid if the cilinders are to be linked in the same hole in the hinge and with the same attack angle.

Nuno

jetjohn

Thank you all for the replies so far.

The reason for this idea was to stop doors twisting due to cylinder pull on one end only.
When I tried to fit the cylinders their full stroke closed to open worked perfectly when fitted on the bar between the two sets of hinges.
Photos attached showing closed & open positions.
The ball link was drilled through as per photo just to achieve the right length for movement. It was the only thing I could find to try out the idea quickly.
If it seems to be O.K. I was going to thread the one end & put a washer & nut on it & a simple 90 deg bend on the other end.
If using a single cylinder it was going to be mounted centrally and retained by a couple of wheel collets.
If two cylinders required, one at each end.

Tested with cylcle pump & all seems O.K. will pressurise system & try later.

All the best,
John C