From Wikipedia, the free encyclopedia

Pratt & Whitney R-2800The Pratt & Whitney R-2800 Double Wasp was an
aircraft engine, and part of the long-lived Wasp family. It was a two-
row, 18-cylinder, air-cooled radial design. Displacement was 2,804
cubic inches (46 liters); bore and stroke were 5.75" and 6".

Specifications Pratt & Whitney (R-4360-51) Wasp Major
General characteristics
Type: 28-cylinder supercharged air-cooled four-row radial engine
Bo 5.75 in. (146 mm)
Stroke: 6.00 in. (152 mm)
Displacement: 4,360 in³ (71.4 L)
Length: 96.5 in. (2 451 mm)
Diameter: 55 in (1397 mm)
Dry weight: 3,870 lb (1,755 kg)

Specifications Wright R3350
18 cylinder, air-cooled, two-row radial
displacement: 3,342 cubic inches (54.8 liters)
bore x stroke: 6.125 x 6.3125 inches


I grabbed these specs from a quick Google search. At least in terms of
the larger later-model radials, the stroke is a little greater than
the bore. But as a percentage, its not a huge difference like in some
car engines where the bore exceeds the stroke by 25% or more. I don't
know if radials qualify as "strokers" by those numbers.

Harry "we'll think about and engine next year" Frey



On Apr 19, 9:30 am, wrote:
Looking over the available illustrations on the net it appears
that the typical radial aircraft engine had a stroke longer
than the bore (undersquare). Is that right?

It would make sense for high torque at lower RPMs.

--

FF