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Oil door in cowl bowing in flight

JackinMichigan

Well Known Member
The access door on top of the cowl has a significant bow to it while in flight. I've made the habit of taping it down with military grade duct tape, but that won't be an option once I get it painted. I feel as though I need to stiffen this door somehow. It's contoured to the cowl, so a simple fat bar stiffener won't work here. Anybody got any ideas?
 
I epoxied two plies of carbon fiber to the under side of my oil door and that seemed to work for me.
 
I used

I used Soric fabric. Interesting stuff, goes on like fiberglass cloth but doesn?t absorb the epoxy except in the hexagon cells. Makes the fiberglass sheet 8 times more rigid, according to the literature...
 
Jack,

Get some aquarium tubing from your local pet or hardware store. It doesn't have to be very large diameter.

Fiberglass it under your filler door. Three layers of the BID most of use should work. Your call if it you want to make it an X, a box, or both. Leave the tube long enough you can just pull it out, after the fiberglass hardens. Tape your door shut with the tape to it holds the correct position.

Be CAREFUL not to fiberglass your filler door shut. You can always remove your top cowling while you do this.

That will stiffen the door significantly and keep it from flexing in flight.

BTW, are you flying out of 1D2? I learned to fly there many years ago! Say "Hi" to Doug S., when you see him next. We were roommates at Western.
 
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Mine bowed also. I installed two ribs - fluted to make the curve - on my first RV8 with the fiberglass door. On my current RV8, I made the door out of .063 aluminum and it doesn?t bow at all, and lays down nice and flat.
 
Mine started popping open in flight, so I had a buddy lay up a carbon fiber rib on the back of mine about 1/2" wide running from top to bottom. We preloaded the door slightly flatter than perfect fit, and everything looks great after the last two hundred hours. Carbon fiber is really stiff, and I think that it is generally easier to work into organic shapes than fiberglass.

I don't have any photos handy... sorry.
 
BTW, are you flying out of 1D2? I learned to fly there many years ago! Say "Hi" to Doug S., when you see him next. We were roommates at Western.

I got my license at Kitze Aviation out of 1D2 and I live maybe 1-1/2 miles from that airport. Unfortunately there's a multi-year waiting list for a hangar out there, so currently I'm at Willow Run (KYIP).
 
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I got my license at Kite Aviation out of 1D2 and I live maybe 1-1/2 miles from that airport. Unfortunately there's a multi-year waiting list for a hangar out there, so currently I'm at Willow Run (KYIP).

Small world. Back when I got my license there, it was a Cessna Flight school, we flew brand-new 152's and I lived in the apartments off the north end of the runway.

Talk to Doug, the other day he mentioned he was thinking of selling the 120. That will free up a hangar but I'm not sure if your -10 will fit in it or not.
 
I used Soric fabric. Interesting stuff, goes on like fiberglass cloth but doesn?t absorb the epoxy except in the hexagon cells. Makes the fiberglass sheet 8 times more rigid, according to the literature...

It needs a layer of glass over it. I tested the stiffness, and it was more than 8 times stiffer for a 2-core-2 vs 4 layer. 3mm Soric
 
No flight test yet, but I'm following the recommendation from elsewhere on the site to save the cut out piece of the cowling and bond it to the bottom of the oil door. This extra piece of glass should significantly stiffen the structure (stiffness goes up with the cube of the thickness; should be at least 8 times stiffer!)
 
I'm pretty sure the RV-10 plans specify that a piece of 1/8" thick foam core material (supplied in the kit) with the edges scarfed, be bonded to the inside surface of the door and then a layer of glass cloth epoxied over it.

Makes the door as stiff as an .063 aluminum one.
 
I'm pretty sure the RV-10 plans specify that a piece of 1/8" thick foam core material (supplied in the kit) with the edges scarfed, be bonded to the inside surface of the door and then a layer of glass cloth epoxied over it.

Makes the door as stiff as an .063 aluminum one.

Yep. It is extremely stiff when built to plans. I can't imagine it bowing in flight.
 
The access door on top of the cowl has a significant bow to it while in flight. I've made the habit of taping it down with military grade duct tape, but that won't be an option once I get it painted. I feel as though I need to stiffen this door somehow. It's contoured to the cowl, so a simple fat bar stiffener won't work here. Anybody got any ideas?

Being a builder I assume you have some epoxy. Email your address and I will send a patch of 3mm Soric - it is expensive to buy a small portion and I have scrap that big. Trust me - if the door is flimsy and the hinge is not part of the problem, this will stiffen the part and it is light too. Easy to do, really easy. One layer of glass and use peel ply or preload the glass so it is minimal thickness.

Do have some glass left over too?

Bill
 
I'm pretty sure the RV-10 plans specify that a piece of 1/8" thick foam core material (supplied in the kit) with the edges scarfed, be bonded to the inside surface of the door and then a layer of glass cloth epoxied over it.

Makes the door as stiff as an .063 aluminum one.

Please provide the part number.
Thanks,
Carl
 
Door

I ended up trying the foam core on a test piece and compared it to a test piece using SORIC.

The SORIC piece was MUCH more rigid than the piece using the foam core...

Just a data point...
 
Is the bowing along one of the edges or truly in the center of the door? I have a very stiff door, but I experience a slight bowing at the rear corner on the same side as my latch. Since my latch is in the center of the door edge, the aft end is bowing on my due to the high pressure in the upper cowl. If I had it to do again, I would have installed two latches, each near the corner to mitigate this issue.
 
No flight test yet, but I'm following the recommendation from elsewhere on the site to save the cut out piece of the cowling and bond it to the bottom of the oil door. This extra piece of glass should significantly stiffen the structure (stiffness goes up with the cube of the thickness; should be at least 8 times stiffer!)

+1

I did this on the 6 and it makes a very stiff door that won't bow.

Larry
 
I ended up trying the foam core on a test piece and compared it to a test piece using SORIC.

The SORIC piece was MUCH more rigid than the piece using the foam core...

Just a data point...

I guess there is nothing wrong with much more rigid, but in the context of RV kit engineering, just rigid enough is best :D (especially when it means using an inexpensive piece of foam that takes no additional effort to obtain.

The RV-10 prototype has 2000+ hrs now and its oil door was made exactly as shown in the plans. It does not bow up in flight from plenum pressure.
 
Is the bowing along one of the edges or truly in the center of the door? I have a very stiff door, but I experience a slight bowing at the rear corner on the same side as my latch. Since my latch is in the center of the door edge, the aft end is bowing on my due to the high pressure in the upper cowl. If I had it to do again, I would have installed two latches, each near the corner to mitigate this issue.

That is why the kit specifys a cam lock in each corner.
 
What I've seen in a couple RV-10s that installed the hidden hinge, is that the air pressure on the door will cause the hinge side to come up about 1/16" - 1/8" in flight. due to play in the hinge.

Unfortunately, I learned the hard way. My first door came of on an approach in IMC.

My second door has much more secure Hartwell latches on the forward and aft side of the door. I just used the plans foam as a stiffner. I made some minor adjustments to the hinge. The door is rock solid and doesn't move anymore.
 
I agree with Scott if you like the two camlocks. Then the supplied piece of foam glassed over works well, but it is hard to get a good looking oil door.
What worked the best for me was to glue/attach a piece of 032 alclad to the bottom with prc. I have used the hidden hinge that was sold by Avery. Then used two latches. Latches and hidden hinge riveted through the door and alclad. Minimum effort, no bulging and nice finish.
 
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