I've tweaked my cooling system to provide just what I want for High DA, High GW, Vy climb to altitude by sealing every possible gap in baffles, between cyl, and inlets, I've added louvers to the lower exit area for increased mass flow, have the Oil cooler blocked 60% and can consistently climb at Vy to any altitude without any cyl exceeding 400 deg and most of the time never above 390. At Vmax (2700rpm limited FP) of 191 MTAS (68% power) 8K DA, CHTs range from 296 - 308. The low cruise CHTs provide plenty of margin to start throttling the exit for decreased cooling drag while leaving the modifications in place for climb. The only way to do this is to have an inflight variable exit area or cowl flap. My max exit area is fixed and set for the climb conditions discussed. My cowl flaps primary purpose is to allow a reduction in exit area while closed with perhaps some marginal benefit while open in reducing the pressure at the exit to further aid in climb cooling.
in the closed position very little increase in frontal area exposed to freestream while taking advantage of the sloping exit ramp to decrease the area. ratio of exit areas from open/ closed is approx. 1/.65 - remember when open the exit area remains 1/1 with the mods I've already made.
In the down position no net change in exit area but may have some benefit of pressure reduction to help the flow - not counting on this and don't really care as the system is set-up for this exit area already.
Probably need a bit more clearance with the exhaust. I will probably cut an inch or so off the exhaust pipe.
The cowl flap is not hinged to the cowling yet it is just resting in place.
Now the hard part: how do I actuate the flaps? I have some ideas but would be interested in the collective brain trust.
Whatever the method it has to be able to hold the flap both open or closed (and in between) AND be easy to disconnect for cowl removal.
What say you?
in the closed position very little increase in frontal area exposed to freestream while taking advantage of the sloping exit ramp to decrease the area. ratio of exit areas from open/ closed is approx. 1/.65 - remember when open the exit area remains 1/1 with the mods I've already made.
In the down position no net change in exit area but may have some benefit of pressure reduction to help the flow - not counting on this and don't really care as the system is set-up for this exit area already.
Probably need a bit more clearance with the exhaust. I will probably cut an inch or so off the exhaust pipe.
The cowl flap is not hinged to the cowling yet it is just resting in place.
Now the hard part: how do I actuate the flaps? I have some ideas but would be interested in the collective brain trust.
Whatever the method it has to be able to hold the flap both open or closed (and in between) AND be easy to disconnect for cowl removal.
What say you?