Hangar 9 retract problem

Hi,

In another post, it was pointed out the H9 ( Hangar-9 ) retract bellcrank has a problem coming loose, and perhaps even failing. When I started working with the retracts when building my new P-40 Warhawk, I saw what was happenig.

The bellcrank pivots on a screw that is held in place by a piece of plywood at the bottom. The screw goes into a blind nut that can move when the retracts operate. It is a very flimsy mount since it is only anchored at one end and the bellcrank screw wobbles when the retracts are deployed, giving a erratic and sometimes limited movement.

To fix the problem, I added a longer screw, with a additional plywood support, just under the head of the screw. The screw is now supported at the top and bottom. This gives a very positive, secure pivot point for ther bellcrank and makes a very reliable retract movement on the P40 retractable gear.

I did not show a picture of the original parts in place, they turned out blurry, but you will be able to see how the original is done by looking at your own aircraft.

The next few posts will show the pictures of the original parts out of the plane (first picture), the modification parts (second picture) and finally the modification mounted in the plane.

===================

The first picture ahows the parts that were removed from the wing.

===================

The second picture shows a picture of the parts that you need to install - there is a longer screw, and a plywood brace.

You will notice I removed the original phillips screw and then added the longer allen screw with the plywood support just under the head of the allen screw. I do not have the dimensions of the plywood, I just it cut out by LAR (Looks About Right) and marked the location for the allen screw hole, and made sure the plywood was wide enough so it can be glued to the rib.

The parts are (in order from top down looking from the underside of the wing):
18 X 3mm Allen Screw
Washer
Plywood support
Washer
Bellcrank
Washer
and they are screwed into place with the allen screw into the existing blind nut already in the wing

Note: if the existing blind nut is loose, make sure you remove it, give it a light coating of epoxy, and put back in place so it will be secure.

==================

The third picture shows the parts installed in the wing.

With the assembly together, place it in the wing and tighten down the allen screw. Tighten the allen screw so it JUST touches the bellcrank, and the bellcrank can still pivot freely.

Then swing the plywood support so it rests against the rib.

With the plywood support up against the rib, put epoxy on the plywood support and epoxy it to the rib.

Finally, put a drop of epoxy in the allen screw head to stop it from backing out when the retracts are working.

Let me know how it works for you:

I’m retired, so the next step is to start saving my pennies for the Saito 100! I can’t wait to get this thing in the air.

Fly4Fun,


Wayne Miller

Picture 1

Picture 2

Picture 3

Wayne,

I have a hanger 9 P-51 that is all set up, but that I have not flown it yet. I have been reading about all of the problems with the stock gear. I am half tempted to put Robart pneumatic gear it right off the bat. Your post had got me wondering if I shouldn't do the mod you did, and then replace the stock strut with 3/16" music wire that guys have been doing on the Mustang threads.

What are your thoughts? Do you think the two modifications combined would make for stable and reliable landing gear? I would hate to belly land this plane with what I have into it.

Adam

Hi Adam,

The modification is quite easy to do and really made a difference and makes a more solid retract movement. Since some people are running on the stock gear with no complaints, I think it will be OK, it really beefs it up.

I used a 3mm X 18mm allen screw, but a little longer, such as 20mm or 25mm would allow you to put in a thicker upper plywood support.

It will cost very little for the modification, one allen screw, a bit of plywood and some epoxy - but it would cost a whole bunch for new retracts - I'd make the modification, its simple to do, then evaluate the before and after - I think you will be pleasantly surprised.

I won't have mine in the air for a while, I need to get an engine, so I don't know about replacing the landing gear wire.

Let me know your thoughts after doing the mod - we may be able to help a lot of people here.

Fly4Fun,

Wayne Miller

Wayne,

I am going to fly her for the first time this weekend. I will wait to do the modification until after I have given it a try completely stock. I will then do your modification and install the 3/16" music wire at the same time. If there is room for a longer allen head bolt I will give that a try and use a little thicker plywood. I am with you, I don't want to take any chances, but I would love to get the stock gear to work securely.

I will let you know how it works. If there are any other guys out there who beat me to it, please post your results.

Adam

Hi Adam,

The longer allen screw should be no problem, there is lots of room for the 20 or 25mm.

If you use the 18mm as I did, you have to keep the washers thin so the screw has lots of thread going into the blind nut.

Doing a before and after test should give a good test. Thanks for taking the time to help, I look forward to your results.

Fly4Fun,

Wayne Miller

I think the bell crank setup you're describeing here is only on Hangar 9 retracts that are rotateting like in their P-40 Warhawk, and F4U Corsair and not in the Mustangs since it doesn't have a rotateing retract setup.

Ahh, that may be the case. I will tear into and see.

Adam

Thanks guys,
I have a H9 Corsair and although I have strenghtened the retract it self I have done nothing to the bell crank. I have a fly in this weekend and will try that to see if it helps with the movement. I love the plane, but am not ready for 250 more in air retracts.

Hi,

I'm not sure if this is the same with all the Hangar 9 Warbirds, I only have the P40 Warhawk and it has the rotaing retracts.

If any knows of the other Hagar 9 warbirds have the same retracts, would you let us know? Thanks.

P.S. I can't seem to post to the thread some days, so I may not be answering promptly.

Fly4Fun,

Wayne Miller

Wayne, I'm pretty sure that, as mentioned in an earlier post, only the rotating retracts have the bell crank system. I have, along with two other fliers have been flying the Hangar 9 Corsair for about two years and the only problems encountered were weak struts, which was remedied by replacing with a heavier wire, and the original ball links were too small and would pop off, this was fixed with heavier links. I have not heard of any way to, or need to try to counterbalance gear, a good retract servo whould be able to handle the load with no problem. Cliff

Thanks for the information Drone Pilot.

Fly4Fun,

Wayne Miller