.

I doubt very much whether there would be an appreciable difference in temps wiht that gap closed off. As it is the engine runs very cool and at with apparently surplus cooling air pressure. I also think it would be hard to duplicate exact conditons for each flight, but then again maybe not considering the emax data logging of all the parameters.

One thing is for sure, that escaping colling air is doing nothing productive and is disturbing the exterior airflow somewhat. It was designed to be closed in flight so I would hope it would be.

In reply to:


I doubt very much whether there would be an appreciable difference in temps with that gap closed off. As it is the engine runs very cool and at with apparently surplus cooling air pressure. I also think it would be hard to duplicate exact conditons for each flight, but then again maybe not considering the emax data logging of all the parameters.

One thing is for sure, that escaping cooling air is doing nothing productive and is disturbing the exterior airflow somewhat. It was designed to be closed in flight so I would hope it would be.


I did try this, sort of. My IA skillfully fitted my oil door with adhesive gasketing, with a double layer on the edge that lifts away. He warned me that if the pressure difference was sufficient, the new material might be blown away… which is exactly what happened, two hours into the first decent flight after the work was done, although the gasket did its job until then. The whole sad story is told below in pictures.

Did it change temps? I was mostly interested in my cylinder 2 CHT, which runs hotter than the rest of my cylinders (seems to be that way on most SR22s). I wanted to prove or refute the theory that the difference was attributable to the air escaping through that gap, but everything looked the same.

Ten seconds after the last photo was taken, the gasket departed the airplane completely - some farmer is probably puzzled right now - so I was able to compare ‘Before’ and ‘After’ temps during the same flight. I noted no difference at all.

OTOH, I didn’t notice any change in TAS or handling either, so the escaping air has negligible effect on the aerodynamics of the airplane in a practical sense, which is what one would expect.

Mike
I had the same problem when I installed the “gasket”. My solution was to use the ever useful Duct Tape to hold the gasket in place. Works like a charm. Not visible when closed and no farmer has to worry that the sky is falling. Of course, when the hatch is open its not as pretty as yours!
Richard

#2 Cylinder would not likely see a measurable effect either way. The idea behind a pressure cowl is to create an even homogenous pressure deck above the engine. There is ample turbulence so an individual cylinder would not see much difference. That is unless it is, say, close to the oil cooler where the air is being stolen from the backside.

The solution to the bowing door is not stuffing the anticiapated gap with gasketing. Over-gasketing puts excess strain on the hinge and latches and may lead to cracking.

One good solution would be to install an extra latch to hold it in place. However, the shape of the core of the panel precludes that being a simple modification.

In reply to:


Works like a charm.


Richard,

Did it make a difference to your temps?

  • Mike.

To be honest, I don’t know. I do know that my temps have been good since it was installed but am not sure if that is due to technique or the seal. Sorry, not a very good answer.
Richard

Why not simply create a ‘flap’ of rubber around the perimeter of the inside of the oil door opening, attached to the cowl not the door, using the same stuff used to seal the baffles around the cowl? The high pressure on the inside should keep it tightly sealed around the door. (I wonder how much of the deformation around the oil door (the gap at the leading edge) is created by internal pressure and how much by ram forces from the slipstream getting into the gap…I don’t know if such an ‘air dam’ would affect the deformation, if at all.)

Tim

It is almost certainly from internal pressure working on pushing the whole door up a and out. The tiny little lip at the front is streamlined when not in motion. When in motion it is still within the boundary layer (not taking into consideration the propwash).

The seal may stop the air from escaping but it will do nothing to stop the flexing of the door.