New Britain herald., 1927-11-02

fThis Is the seventh Tn the Herald's series of articles dealing with aviation and its various phases in this country)
 (By Frank J. Carmody)
 In considering all the factors that go into the building Of safe, reliable airplanes. power must be rated first. An au,oM obile that develops engine troupl. simply stops and usually no damage Is done beyond discommod- ing and disconcerting the motorist. If. however, an airplane engine de- velops < malady that saps it of its strength and speed. the pilot and other occupants may find themselves Tn a predicament from which ex- trication either Is difficult or impos- sihle. The motorist may stop any where, but the avator must be more discriminating.
 Thanks to the progress Of airplane engine design, however, the aircraft today have wide margin of safety in the matter of power. The story of the development of plane motor ist is one of the most interesting in connection with aviation progress.
 The Air Cool Motor
 The current summer has seen the nation paying tribute to the heroes of an astonishing array of aerial accomplishments And while the public sang their praises, Lindbergh, Chamberlain, Byrd, Maitland and other stalwarts of the air rendered homage to the motors that made their achievements possible. The admirable modesty with which these pilots insisted upon proper credit being given to their planes, served to create degree Of interest, in en- zines 2 curiosity however, that has been concentrated upon one type. The engine in question, the air-cool- ed radial, certainly is deserving of attention because of its service re- cord, but 1t does not stand altogeth- CT alone in the field of aircraft power.
 Water Cooled Type
 Despite the on-rush of air cooled plants, the water-cooled type which played so conspicuous role in aviation before and since the war, while not so much in the limelight of late, is being developed to even higher standards of performance and reliability. Each type seems to be finding particular sphere where it's characteristics are best adapted to the needs of the field.
 The division naturally, is made air-cooled radial seems established under the 500 horsepower standard. Over this size the l2-cyliuder water cooled horizontal holds the reins. Motors built on each principle are proving popular between 500 and 100 horsepower, however.
 Pratt & Whitney "Hornet'
 Design is the factor most respon- siblc for this division. Because of the higher head resistance of the radial plant, a limit seems placed upon the size to which it may be built That this limitation will be over come is confidently predicted fin many quarters. The Pratt and Whit ney Hornet" nine-cylinder radial used by the Navy, is about the largest plant of it's kind. It is cap able of developing 525 horsepower. Water cooled motors, with less frontal resistance, run as high hs 800 horsepower.
 The ordinary horizontal 1e-cylin- der motor has another advantage ill that a much higher compression ratio may be used. Ratios of 10 1 have been employed in engines of this kind while 5.5 to 1 is as high as most of the radials go. Higher compression mean. a greater amount of heat to be dissipated, and Tn the case of the radial, longer fins with their excessive resistance would be necessary.
 Advantages and Disadvantages
 The higher speed and greater power developed by the water-cooled engines are advantages, however, that are offset by certain virtues which the air-cooled radial possess