rotccapt

i am working on a midwest super stearman and i chose to power it with a zenoah g26 my question is regarding the dummy radial that comes with the kit. since i am using a gas engine i will have several holes in the cowl for different parts. the dummy radial will have holes between the cilenders where air can pass through and with the position of the holes for the cylinder head the air will be routed out the bottom of the cowl. so my question is if i have about 3times the inlet area for the outlet does it matter how large the inlet is?

here is a few picks what do you think?

Campy

My Feedback: (1)

The more inlet area you have (within reason), the better.

The KEY THING is the inlet/outlet ratio. The IDEAL ratio is 1:3 (1sq inch of inlet to 3 sq inch of outlet ). Depending on the total area of inlet, engine size and average temperature you fly in, you MAY be able to get away with a 1:2 ratio.

The 2 heat generators are the head and the muffler. With the head of the engine exposed (as per the photo) and the other openings, you should have no problem with a 1:2 ratio.

The other thing you want to check is HOW the air is flowing from the inlets to the outlets. You may want to put some baffles inside the cowl to direct the airflow over the muffler and towards an outlet if it doesn't look like you will have adequate airflow.

pahtreek

My Feedback: (1)

The rule of thumb is you want 3 times the OUTLET area as the inlet area. This way the air is pulled out quickly. If all that air is forced in with no where to go, it will just sit there. It looks like you have plenty of outlet assuming the muffler does not block up all the outlet area. I dont think you even need to cut the upper pieces between the radial engines, just the 4 bottom ones so that air is forced over the engine head and not up into the upper cowl where is does nothing for you. I hope this helps.

-Patrick

** sorry to reiterate what was just said, but we posted responses at the same time....lol