Johnson Creek, June 10

[TrueAirSpeed]

[Utah-Jay]

A Bearhawk in it’s home environment, beautiful

[Nev]

Nice! Could you tell us about your cowl flap arrangement?

[Mark Dickens]

I'm more interested in how many hours per week you spend polishing those wings!

[TrueAirSpeed]

Nev, the cowl flaps are an after market product sold by https://antisplataero.com/products that deals mostly in the Vans RV world. They are electrically operated and when both are opened provide about 27 square inches of additional heat extraction. They are either fully opened or fully closed, no in between. There’s a toggle switch and indicator light associated with them. In flight closed, they increase the airspeed by approximately one knot. Opened they reduce CHTs between 2 and 5 degrees, depending on OATs.

Mark, I have to say I polished them three years ago in the build and haven’t touched them since. At condition inspection time, I’ll probably use some Mother’s Mag and Aluminum Polish and a non-orbital buffer to touch them up. The plane is hangared most of the time when not in use.

Terry

[Nev]

Thanks Terry, I was on the Aerosplat website just yesterday, so good timing. I really like the Aerosplat concept, and having a simple Open/Closed switch. It'd work well on the oil cooler butterfly valve too.

Is that an air scoop on the top cowl - and if it is, I was curious if you found it helped with cooling ? I couldn't tell from the photo where it sat in relation to the high/low pressure compartment.

[TrueAirSpeed]

Nev, the scoop is a Vetterman product that directs cool air to a 4 inch NACA duct that in turn is connected to 4 inch scat tubing that goes to a 17 row oil cooler, placed near the center of the firewall. So far this year my highest oil temp has been 184 degrees F.

Terry

[whee]

I’m surprised the cowl flaps do so little. Mine are very similar and cool my CHTs by approximately 20F.

[TrueAirSpeed]

Whee, that’s good to hear. The above figures are my best estimate from yesterday’s flight.