The First Airplane Diesel Engine: Packard Model DR-980 of 1928 Part 7

[26] Letter, Richard Totten to National Air Museum, January 28, 1964.

[27] Letter, Richard Totten to National Air Museum, January 28, 1961.

[28] _Aero Digest_ (February 1931), vol. 18, no. 2, p. 58.

[29] "50-Hour Test of Packard Diesel Aircraft Engine," Packard Motor Car Company, Detroit, Michigan, serial no. 426, test no. 234-73, February 19, 1930.

[30] Blower in this sense refers to a low-pressure air pump (supercharger) designed to increase cylinder scavenging efficiency by blowing out exhaust ga.s.ses. In doing this it also increases somewhat the amount of fresh air introduced into the cylinders. Woolson invented a 2-stroke cycle blown engine; the patent was issued in 1932 (patent 1853714) with rights a.s.signed to the Packard Motor Car Company. (Woolson himself died in 1930.)

[31] A 2-stroke cycle engine completes 360 of crankshaft rotation in what it takes a 4-stroke cycle engine 720 to accomplish. A 3-cylinder two-stroke cycle engine therefore has the same capacity to do work as a 6-cylinder four-stroke cycle engine. For this reason the former type of engine is both more compact and lighter than the latter type.

The above advantages, plus the increased efficiency of the blown 2-cycle diesel, are discussed in _Flight--The Aeronautical Engineer Supplement_ (December 26, 1940), vol. 19, no. 11, pp. 545 and 552.

[32] Packard advertis.e.m.e.nt--_Aero Digest_ (June 1930), vol. 16, no. 6, p. 23.

[33] _Aviation_ (March 15, 1930), vol. 28, no. 11, p. 531.

[34] _The National Aeronautic Magazine_ (April 1932), vol. 10, no. 4., p. 18.

[35] Appendix, p. 47.

[36] See Woolson's patent 1794047, issued in 1931 and a.s.signed to the Packard Motor Car Company. "An object of my invention is to automatically regulate the compression ratio in an engine inversely to the speed...." See also his patent 1891321, issued in 1932 and a.s.signed to the Packard Motor Car Company. It describes a similar but nonautomatic system. Woolson therefore fully realized the disadvantages of the high cylinder pressures his engine developed at high rpm's.

[37] Letter, Clarence H. Wiegman to National Air Museum, November 1, 1961.

[38] Ibid.

[39] Major George E. A. Hallet, U.S. Air Service, former director of engineering division, McCook Field, Dayton, Ohio.

[40] "Test of Packard-Diesel radial air-cooled engine," Navy Department, Bureau of Aeronautics, Report AEL-335, July 13, 1931, BuAer Proj. 2265.

[41] _Aviation Week and s.p.a.ce Technology_ (February 19, 1962), vol. 76, no. 8, p. 101.

[42] _Aeronautics_ (October 1929), vol. 5, no. 4, p. 31.

[43] Letter, Richard Totten to National Air Museum, January 28, 1964.

[44] According to Frederic E. Hatch of the National Air Museum, it is possible that the engine failed because the fuel injectors became clogged. He notes that the airplane refueled at several fis.h.i.+ng ports, and therefore must have used diesel oil set aside for fis.h.i.+ng boats.

This oil was generally quite dirty. As a result it was routine for the fishermen to have to clean engine oil filters frequently enroute. The oil filters of the Packard diesel could not be cleaned in flight.