Dick Rutan has been doing a
lot of cooling related testing on the Voyager and during his test for optimum oil cooling,
he discovered an interesting method to improve cooling air flow through an oil cooler.
Using the Voyager water manometer, Dick found that with an oil cooler mounted on the
inside of a cowling, such as a Long-EZ does, where the cooler is in the high pressure
plenum of the cowl, and vented to the free stream, the following delta 'P' measurements
were true.
With NO reverse scoop over the oil cooler (you can see the cooler
from outside) the pressure differential was 1.8" of water. He installed a reverse
scoop per plans, still 1.8" of water delta 'P'. He moved the reverse scoop forward,
exposing half of the oil cooler – 3" H20
delta ‘P'! A dramatic improvement to say the least. Next he moved it forward enouqh
to expose the whole of the oil cooler - 3.8" H20
Delta 'P', and much cooler oil temperatures. If you are having oil temperature problems in
your EZ, try this neat trick:
Click to enlarge
We would like to thank Dick and the Voyager program for this very
helpful hint and also for his help and use of his instrumentation for the previous article
on engine cooling.
