Guys
After battling with cooling issues on a plane I am working on I decided to
measure the pressure differential in the cowling. Being very difficuilt to hold
a manometer perfectly vertical it was decided to use either an electronic
measuring device or make up something ourselves.
One of my friends remembered an article in an old issue of Sport Aviation where
an ASI was used. We copied this method and it works great.
Simply run your pitot line into the cooling plenum/chamber (high pressure) and
run the static to the underside of the motor (low pressure) and go fly.
30MPH/26.1K = .44"WG
40MPH/34.8K = .79"WG
50MPH/43.5K = 1.23"WG
60MPH/52.2K = 1.77"WG
70MPH/60.9K = 2.41"WG
80MPH/69.6K = 3.15"WG
90MPH/78.3K = 3.99"WG
100MPH/87K = 4.92"WG
110MPH/95.7K = 5.95"WG
120MPH/104.3K = 7.09"WG
You are looking for a reading of around 100mph (4.92"wg) or better to cool
efficiently.
I hope this information will benefit somebody.
Regards
Dene Collett
Avlec Projects cc
Port Elizabeth
South Africa
