Prony Brake

The break horsepower of comparatively small engine is determined by means of a Prony Break.
The break consist of a flexible band or strap carrying a number of wooden blocks, which encircle the engine flywheel or a break pulley mounted upon the engine shaft. The wooden blocks are in contact with the surface of the wheel and the strap or band may be tightened or loosened upon the break wheel by means of a hand adjustment.

The horizontal distance from C to the center of the engine shaft is the length (r) of the break arm. The Prony device is a friction device and the power developed at the rim of the break wheel is dissipated as heat.



Case:
Determine the length of a Prony Break arm so that bhp= 0.001 Nw.

bhp = 2 (phi) r Nw / 33,000

r = (0.001 x 33,000) / 2 (phi)

r = 5.25 ft

Electric Generator Engine

From Ella Yuan

Boom

Boom is a prototype for a new supersonic passenger aero-plane that will be able to fly New York to London in 3.5 hours, slightly quicker than Concorde used to. But that's not the clever bit.

The smart thing about Boom is that it uses existing technologies to keep costs low, and the business model is based on flights being about the same price as Business Class is today.

Apparently Boom is already in development and test flights are planned for late 2017



©Richard Oldham