Please, I didn't intend to reignite the air vs. liquid cooled engine debate nor intend to diss certain engineers. I admit I'm not schooled in the math, but the concepts behind heat transfer are simple. The devil is in the details.
I made a forest vs. trees type of observation. I'd love to have any excuse to by an engine that offers the advantages of a 2-stroke turbo diesel. It's just that I'm not willing to stick my leg out the side of the fuselage to do so.
My challenge to the engineers is to find a way to shed the necessary heat without penalizing the airframe. Since the rate of transfer is reduced, and since mass (or drag anyway) is limited, then I guess the transfer of heat must be given more time to work. This must be old hash somewhere.
I hadn't seen the liquid-cooled-air-power website before today. The pictures of their radiator are quite revealing. Its doubled over which probably serves to increase the amount of time that heat is transferred. I would guess that air exiting this radiator is hotter than a single plane radiator all else being equal.
Since the location of the propeller flange and the slice-o-wonderbread shape of the RV-9 firewall are pretty much a given, then the cowling is going to be cavernous compared to the size of the Wilksch engine. This may be sufficient space to design effective diffusers and nozzles (rather than mere passages) that work with appropriately shaped/sized radiators.
I like the idea of the Wilksch engine. I don't like the idea of handicapping the airframe. I sure wish I had the funds to p-o-c it myself.
Other potential heat sinks:
Hammer a cowling out of 1/2" aluminum then carefully rout miles of groves/fins on it. Bond standard flat radiator tubing on the inside. Your spinning propeller will ensure that you'll never again fear having enough cooling while being 24th in line for takeoff at Oshkosh.
Bond a length or two of radiator tubing to the skin between each wing rib then hook em up. P.S. if you do the right combination of series and parallel connections and fly full-throtle long enough, you'll be able to generate enough electricity for a wig-wag flasher.
Bond surplus Carrier/York a/c tubing to the bottom of the fuselage. Don't forget to make a U-turn at the tail.
Bond radiator tubing to the underside of the wing. A handful of parallel loops oughta to the trick.
Bond radiator tubing to the top of the wing at the appropriate depth of chord. Then bond PC heat sinks to the tubing at alternating angles and call them vortex generators.
And if, for crying out loud, you just gotta have that massive radiator up front, at least put it on a tray that can pivot up and down. Use a cowl flap like cable and knob so the pilot can control the amount of droop. Drop it down for high power/low speed regimes and tuck it up for less demanding regimes and show times. In your spare time develop an automatic temperture sensing system to control the droop with Lego servo motors.