Help researching T6 - SNJ - Harvard engine cowling designs

[Mark_Pilkington]

Hello folks,

I am trying to explore possible variations in the design and production of T6 / SNJ / Harvard engine cowlings and in particular the internal radius from the outside face of the prop shaft to the inside edge of the cowl nose.

Could I ask those of you with an NAA aircraft in the hangar to take two simple measurements for me and post them, and the aircrafts ID and model in this thread?

I am after two measurements (1 each side of the prop shaft to allow for a cowl that is sitting offset), and to measure in inches down to 1/8" or better the distance from the face of the prop shaft to the inside radius lip of the cowl nose, ideally horizontally from the prop and in both directions.

ie I am trying to measure the size of the "hole" smiles

The two measurements, allowing for a standard diameter of the prop shaft, will then give me the diameter of the internal opening of the cowl, and I am keen to see if this is standardised across the NAA family or if it varies from factory or model?

I am expecting it to be uniform between the T6 and SNJ but I am not so sure about a Canadian Harvard etc

Any assistance would be greatly appreciated.

Regards

Mark Pilkington

[bdk]

36-7/8 inside diameter of the cowling lip per NAA drawing number 78-31002 and 88-31002. This is common to the BC-1A, T-6 and SNJ according to the drawing.

Never seen a Harvard 4 drawing, but the Harvard II was built by NAA and I don't see why the Harvard 4 cowling would be different. The Harvard 4 basic part numbers and many of the detail parts within are the same. Some of the cowling details are different between versions primarily because of the exhaust but I don't think the loft changed.

[Stoney]

Canadian built Harvards are AT-6As with Canadian mods.