hello all,
several kits give you the option of open or closed cowl flaps. my question is when are the flaps open or closed? open when the engine is running,closed when not?vise versa?
thanks in advance
tom
I think it’s usually when taxiing to keep the radial cool, I can’t redall ever seeing them open during flight.
The cowl flaps are there to manage the cylinder head temperatures. Depending on the aircraft, they might be closed or open for engine start, almost always open for runup, takeoff and climb, and closed for cruise and descent. They’re usually opened after landing but might be closed again after engine shutdown. So as in most things, it all depends…
Tom,
Tailspinturtle is right, but there’s also local climactic conditions that have to be taken into account. Is it a cold climate? Is it raining, hot, foggy, winter, summer, snow?
All of these factors determine the engine operating regime the pilot must use to protect the engines and get the most out of them.
For example, one particular DC-3 now owned and operated locally was an ex USAF aircraft, later sold to and operated by Trans Australia Airlines - it has no operating cowl flaps at all - it was fitted with permanently open cowl rings as the aircraft was delivered to the south Pacific - New Guinea in fact - too hot a climate to operate with closed cowl flaps.
In short - there’s no easy answer.
hey guys,
thanks for the info, i guess the answer to my question is,open or closed it dosent really matter.
If you’r posing it parked on the ground, gear down, then you can flip a coin, or build it whichever way you like. Parked, it was just as likely to have them closed as open, flaps down or up, etc.