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BroomstickPilot
16th Feb 2008, 06:09
Hi Guys,

As we all know, the NACA pattern air intake has become ubiquitous on the external surfaces of aircraft of all types and sizes.

Logic tells me that these ought to be less efficient than the old fashioned air scoop that used to stand proud of the surface on which it was situated.

Yet there must be some definite advantage in the NACA pattern because every manufacturer uses it.

Does anybody please know the rationale on which the design of the NACA intake has been based?

Broomstick.

stevef
16th Feb 2008, 07:49
NACA and NASA carried out extensive drag intake studies and tests in the 40s & 50s and the submerged duct was the result. After the required inlet area was calculated, the duct followed the optimum shape, being a width to height ratio of 3 to 5 and a 7 degree ramp angle.

411A
16th Feb 2008, 09:22
In addition to the above, it has been found that the NACA duct, if properly designed, is inherently non-icing.

BroomstickPilot
16th Feb 2008, 11:53
Thanks Guys.

Broomstick.