enginehistory.org

[rinkol]

In 1929 P&W increased the bore and stroke of the original Hornet A (1690 cubic inches) to produce the Hornet B (1860 cubic inches). Apparently there were some problems with the Hornet B since P&W reverted to the 1690 cubic inch displacement for all later versions of the Hornet.

Information on the Hornet B seems a bit scarce - can anyone add to this and expand on the reason for the abandonment of the 1860 cubic inch versions?

Robert

[gwhite]

It's my understanding that it suffered from detonation due its larger, over 6", bore. However this begs the question; how did Wright get away with it?

[tmartin]

Dear rinkol:
Here's what Herschel Smith and Jack Connors have written in re the Hornet B problems:

Smith, Herschel. Aircraft Piston Engines. New York: McGraw-Hill, 1981, p. 107: "...“…careless throttle handling could cause piston dishing and other problems…”
Connors, Jack. The Engines of Pratt and Whitney: A Technical History.
Reston: American Institute of Aeronautics and Astronautics, 2010, pp. 79-80: “…too close to the upper limits of bore size and the challenge of cooling a cylinder with a minimum of surface area to volume...”

Yours,
Todd Martin

[rinkol]

Todd

Thanks. I have the question of what the definition of "piston dishing" is. One sees the use of the word "dish" in the context of pistons having concave tops. In this case is it referring to erosion from detonation?

Thanks
Robert