Re: REFLECTOR: Oil Cooler Question

[john daniel cowan <jdcowan@mail.telis.org>]

Positech.com  builds a larger one, (I bought model #4219mn), they claim is
more efficient than the stewart-warner, for one third less ($207). and they
will put in any size inlet you want, so running bigger oil lines is easy.
They are advertising in Kitplanes and sport aviation now I think. 170 N.
17th St.,
Wheeling, WV 26003    (304) 277-4050.


At 08:29 AM 4/1/99 EST, you wrote:
>On the question; "Do we need two oil coolers using an IO540", the simple
>answer is no, -- however ......
>
> Both Jean Prudhomme and (I think) also Don White are flying their XLs (IO540,
>300 hp) with one somewhat larger oil cooler than what the factory sells and
>uses (two of) in its XL (260hp). They also have a pilot operable flap at the
>naca inlet to increase the surface area and provide a ram effect to the scoop.
>
>I also want to avoid using two oil coolers but have committed (space, purchase
>and building status) to use the smaller oil cooler with modifications as
>follows:
>
>a. I have (somewhat radically from what the builder's manual proposes) changed
>the geometry of the exhaust from my oil cooler and expect a much larger
>pressure drop (thus a larger volume of air through it per time unit). This is
>all empirical, but with a background in the design of steam ejectors some 35
>years ago.
>(Don't know about induced drag, but it looks pretty streamlined).
>
>b. Encouraged by the findings from Scott and Martin's testing of heat transfer
>between the oil lines in the pilot duct, I have:
> - Installed the two lines in the pilot duct without the use of shrink tubing
>(aside from about six inches at each end of the duct). 
> - Separated the two lines with 4 pairs of Adel clamps to avoid heat transfer
>by conduction.
>- Opened the forward end of the duct to the outside (about 6 inches aft of the
>canard bulkhead), and the aft end of the duct (about 2 inches forward of the
>gear bulkhead). The forward opening is "scoop"-shaped with an area of ca. 4
>sq. in.
>The exhaust opening is somewhat larger, ca. 5 - 6 sq. in.
>Both openings have insertable/removable "plugs".
>
>I will install thermocouples at each end of both lines to measure the effect
>of the duct cooling. My rough calculatins of an ideal situation indicates that
>the duct cooling should give me a temperature drop of 30 - 35 degrees (not
>counting the oil cooler).
>
>I am about 2 months away from first flight. Will keep you posted.
>
>Best regards,
>Odd Jorgensen
>N190J  (XL/RG - IO540, 260hp)
>
>