Subject: Bomber Series--Boeing B-17 Fortress (3 of 27)

From: [email-masked]
Date: 28 Jul 94 00:40:06 GMT

>From [email-masked]

A single Y1B-17 airframe (without military serial number) had been 
ordered as a non-flying article for use in static testing.  It was to 
be delivered without installations and tested to destruction to see 
how much punishment the airframe could take before it disintegrated.  

However, the fact that Y1B-17 36-151 had survived an inadvertent spin 
led the Air Corps to conclude that the basic aircraft structure was 
exceptionally robust, so much so, in fact, that the static test was 
deemed unnecessary.  On May 12, 1937, the Army decided to convert the 
static test Y1B-17 into a special flight test aircraft under the 
designation Y1B-17A.  The plane was to be fitted with Moss/General 
Electric turbosuperchargers for its Wright GR-1820-51 (G5) Cyclone 
engines.  

The Y1B-17A was designated Model 299F by the company, and the USAAC 
serial number 37-369 was assigned to the aircraft.  The Y1B-17A flew 
for the first time on April 29, 1938.  The turbosuperchargers were fed 
by a set of intercooler air intakes installed in the wing leading 
edges.  Initially, the turbosuperchargers were mounted flat on top of 
the nacelles, but this arrangement proved to be unworkable.  They were 
moved to the bottom of the nacelles, and the reworked aircraft flew 
again on November 20, 1938.  This time, everything worked well.  The 
turbosupercharged engines delivered 800 hp at 25,000 feet, whereas the 
R-1820-39s of the Y1B-17 could only deliver 775 hp at 14,000 feet.  
The increased high altitude power raised the operational ceiling of 
the aircraft to well above 30,000 feet and the maximum speed to 311 
mph (as compared to 256 mph for the Y1B-17).  The turbosuperchargers 
worked so well that they became standard equipment on the B-17B and on 
all future B-17 models.  

The Y1B-17A was delivered to the Army on January 31, 1939.  After 
completion of the service test period, the aircraft was redesignated 
B-17A.  

37-369 		Boeing Y1B-17A Fortress -- later redesignated B-17A

Specification of Boeing Y1B-17A 

Four supercharged Wright R-1820-51 radial engines rated at 800 hp at 
25,000 feet, and 1000 hp for takeoff.  Maximum speed 271 mph at sea 
level, 295 mph at 25,000 feet.  Cruising speed 230 mph.  Service 
ceiling 38,000 feet.  Dimensions: Wingspan 103 feet 9 3/8 inches, 
length 68 feet 9 inches, height 14 feet 11 15/16 inches, wing area 
1420 square feet.  Weights: 26,520 pounds empty, 37,000 pounds gross, 
45,650 pounds maximum.  Range 2400 miles with 4000 pounds of bombs, 
3600 miles maximum.  Armed with five 0.30-inch machine guns, with one 
gun in each of nose, dorsal, ventral, and two waist positions.  A 
maximum of eight 600 pound bombs could be carried in an internal bomb 
bay.  

Sources:

  Flying Fortress, Edward Jablonski, Doubleday, 1965.

  Famous Bombers of the Second World War, Volume One, William
  Green, Doubleday, 1959.

  Boeing Aircraft Since 1916, Peter M. Bowers, Naval Institute
  Press, 1989.

  United States Military Aircraft Since 1909, Gordon Swanborough
  and Peter M. Bowers, Smithsonian, 1989.

  American Combat Planes, Ray Wagner, Third Edition, Doubleday, 1982.

  Jane's Fighting Aircraft of World War II, Military Press, 1989.

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