IN the following article, Mr. Hall says:
There are two ways to develop more power from less engine - by improving current engines, and by a new start toward a more promising type.
For lowest powerplant drag, use the barrel engine with cylinders parallel to the shaft. “You wouldn't shoot a bullet sideways.”
Six barrel - engine mechanisms are appraised critically in this paper in order to find the best, which is also better mechanically than the crank mechanism. In a cross-head mechanism in which, pistons cannot cock, top speed may be 15% faster than with the crank for same combustion time, and there is almost no useless loading on bearings.
Of all combustion systems, the choice narrows to four-stroke Otto cycle or two-stroke diesel. Specifications are given of a four-stroke gasoline engine using current poppet-valve practice, capable of delivering 3000 hp at 3000 rpm, weighing 2700 lb with 6 sq ft frontal area.
Limitations on cylinder size are all limitations of four-cycle or of crank and poppet-valve mechanisms; larger cylinders are practicable with the two-stroke diesel.
The opposed-piston type is only second-best. Best, is the normal type with double-ended piston members, essentially double-acting with piston inertia serving the flywheel function of offsetting peak cylinder loads to smooth the torque. Possible breathing systems are discussed and specifications are given for a two-stroke diesel capable of development to deliver 5000 hp from 3000 lb with 7 sq ft frontal area.