AERONAUTICS: Wanted: Dirigible Engines

In the U. S. Naval Institute’s Proceedings published last fortnight, Lieut. Thomas G. W. Settle wrote what many an airman already knew: “There is only one bona fide airship engine in the world today— [Germany’s] Maybach.” Last week in his syndicated newspaper colyum, Calvin Coolidge blunderingly deplored: “A naval office reports that the best engine is made abroad,” missing the lighter-than-air distinction. Navy officials protested. Had not the Navy been largely responsible for the development of the air-cooled motor for planes?

None, however, denied Lieut. Settle’s statement that Maybach alone is proven for dirigibles,* that the power-plant requirements of airplane and airship differ as do those of racing car and motorbus. Dirigible engines must: run thousands of hours between overhauls, have low weight and low fuel consumption, be reversible in operation (for maneuvering), cool properly while maneuvering at small air speed, be safe from fire, be capable of repair in flight. In view of the requisites, particularly those of reliability, low fuel consumption and reduced fire hazard, Lieut. Settle predicts the airship engine of the future will be similar to the Diesel (compression-ignition, heavy oil fuel). No U. S. manufacturer has tried to develop an engine for dirigibles because of the tremendous cost of experiment, and limited salability.

*Maybach motors are in the Graf Zeppelin, the Los Angeles; will be in the Navy’s great ZR-4; will doubtless be in the ZR5 unless the Navy first perfects a heavy-oil type now in experimental stage. R-100 has Rolls-Royce condors. R-102 has Beardmore Diesels, an experiment.