oil door pressure

[godspeed]

I have made the hidden hinge oil door with a cessna type latch, but I am concerned about the amount of pressure that will try to force the door open, is one latch enough ? its behind the baffle so I don't know how much pressure is created in this area ? any one that is flying have an idea ?


Danny..

 

[Ironflight]

Danny,

I have two Hartwell latches holding the oil door closed on my -8, and I can see it bowing up in flight at high speeds. Of course, I have no idea how much force is on it, but enough to make it stand about a door-thickness proud of the cowl. My guess is that one latch should be enough - they've got to be pretty strong!

Paul

 

[godspeed]

thanks

when you built it could you push it open with some force without breaking the area where the latch hooks? mine will push open if I push really hard..

I suppose I will add one more, I don't want that
think flying off , I was hoping the area behind the
baffle was lower pressure and pulling a vac from
the bottom its a shame because it turned out
really nice, hidden push button only the circle
with a button under it.. maybe I will test it like
that and see..


Danny..

 

[yarddart]

One latch hidden door , no problemo.

 

[Kyle Boatright]

I have two cam-locks in mine and don't have any problems. Once upon a time I launched for SnF (about 400 NM) and saw that one of the cam-locks wasn't closed on takeoff. The other one held just fine until I landed at SnF.

I don't think this is a high stress area.

 

[gmcjetpilot]

door bulge

I have made the hidden hinge oil door with a cessna type latch, but I am concerned about the amount of pressure that will try to force the door open, is one latch enough ? its behind the baffle so I don't know how much pressure is created in this area ? any one that is flying have an idea ? Danny..

The latch is not the weak link. The doors tend to bulge out between latch and hinge from I guess internal air pressure in the cowl. So stiffen your door between the latch and hinge.

 

[mlw450802]

I have made the hidden hinge oil door with a cessna type latch, but I am concerned about the amount of pressure that will try to force the door open, is one latch enough ? its behind the baffle so I don't know how much pressure is created in this area ? any one that is flying have an idea ?


Danny..

Danny,
You might estimate the max possible load on the door by assuming that the cowl could achieve full dynamic pressure gain and design to those conditions.

For 200 kts at sea level that would be about 0.9psi (~ 6500 pascals depending on your flavor choice).

If your door is say 36 square inches, you would have ~32 pounds force on the door. Applying that midway between the latch and the hingeline will give ~16 pounds on the latch.

This is an unrealistically large but max possible load (for the door in my example. If yours is larger or smaller loads will vary), so designing to that amount should be safe.

-mike

 

[jim]

different with a plenum?

Hi guys,

Just out of curiosity, do the people with plenums still have the bulge of the oil door? I would assume there is still some pressure outside the plenum (from below), but not sure if it's enough to bulge the door.

Thanks in advance for any comments,

 

[kentb]

Not critical...

Hi guys,

Just out of curiosity, do the people with plenums still have the bulge of the oil door? I would assume there is still some pressure outside the plenum (from below), but not sure if it's enough to bulge the door.

Thanks in advance for any comments,

The oil door is not inside the high pressure area of the cowl so the differance between baffle seal and plenum would have no effect.
By the way I have taken off with the two camlocs not locked and the door just lifts up and flaps around in the breeze. I did a loop around in the pattern and landed to lock it down.

Kent

 

[jim]

plenum

Hi Kent,

I realize the oil fill tube is outside the plenum or baffle seals. If you consider what makes the oil door bulge on the standard set up it is incoming air, not confined to a plenum. In the setup with a plenum, at least some builders are also changing the inlet to the round with ducting to the plenum. Hence my question, has anyone noted a difference in the oil door bulging if a plenum is used? If you look at what Bob Axom is doing, trying to totally isolate the high to low pressure areas with the lower baffles and side baffles, I think one should consider the possibility that some of the oil door bulge may possibly be from lower compartment air (low pressure air) going up the sides as well as air from the standard inlet. I personally would think that with a plenum and ducting there is less chance of oil door bulging, and the low pressure air coming up the sides (if that does happen) would not contribute much too the oil door bulge. A plenum and ducting should minimize oil door bulge due to the very fact that it is outside the high pressure area. Just curious to see if there is a difference.

Thanks,

 

[N523RV]

I have the SJ cowl and plenum and can't say that I've ever noticed the oil door bulging at all. I have two hidden hinges and a single flush latch holding it closed. I'll ask the wife if she's ever seen it bulge since she can probably see it better.

 

[kentb]

just to clearify

My door does not bulge. I reinforced it as then do on the RV10, by adding a
layer of fiberglass over a small layer of light styrofoam. My engine is an IO320 with baffles.

Kent