flyrotary@lancaironline.net Mailing List Archive

No, don't think you've lost your sanity - question is were you ever sane {:>) Kidding of course.

I think your plan would cool at your cruise, however, I would be concerned that with the thicker set up you would need higher airspeed to get to the thermal breakeven point after take off. But, drip cooling absorbs a tremendous amount of BTUs as the water evaporates - so long as you can carry enough "cooling drip juice" I would think it would be manageable. What you might consider doing is checking with a radiator shop that builds radiators for the NASCAR shops. For the long high speed tracks, I've read that the cores are as much as 7" thick - the normal tracks use cores approx 3" thick.

----- Original Message -----

From: Monty Roberts

To: Rotary motors in aircraft

Sent: Tuesday, December 20, 2005 12:27 PM

Subject: [FlyRotary] Heat Exchangers/Cooling

Ed A.,

Another question if you will suffer it.

The stock 2nd gen oil cooler has a volume somewhere around 200 in^3.

1/3 heat load to the oil

2/3 to the water

Using a core that is 9in long X 4in thick yields a cooler stack height of around 5.6 200/(9X4)=5.5555 to equal the stock cooler in volume (granted it may not be as efficient at 4 in thick, but it is also moving at 200+ mph something the stock cooler was not designed to do)

There is a really nice SINGLE PASS 4in thick evap core that has a core area of 9X6.375 with tension straps and heavier end plates.

This is a volume of 229.5 which is around 15% greater than the stock oil cooler.

If I use 3 of these, one for oil, and 2 for water do you think I am pushing my luck a little too far?

Seems like it should work if the duct work does it's job. I have a little more freedom in shaping my diffuser and exit than you guys because I am not working around the engine and an existing cowl.

At first they seem a little small, but when you stick them together it is a cooling block that is 19.125X12X4 with the tanks (19.125X9X4 without tanks) which doesn't intuitively seem so small for something going 200 mph.

Trying to save having to drill the baffles out, plus money, plumbing, and weight.

I think there is another 2 pass cooler somewhere between the 8in thick and 6.375 thick model that may be a bit more conservative.

What do you think, have I lost my mind on this one?

Monty