Subject: Number Twenty-Nine in the Series--the Boeing YP-29

From: [email-masked] (Joseph F Baugher)
Date: 15 Oct 92 16:35:56 GMT

>From Joseph F Baugher <[email-masked]>

The Boeing YP-29 was an attempt to produce a modernized version of the 
highly successful P-26 pursuit aircraft.  

The YP-29 originated as the Boeing company's Model 264 project.  The 
Model 264 was a new and more advanced fighter design developed at 
company expense in the interval between the appearance of the XP-936 
(P-26 prototype, company designation of Model 248) and the delivery of 
the first P-26A (Model 266) to the Army.  The new model was initiated 
as a private venture by Boeing in collaboration with the Army, in 
which the company agreed to construct three prototypes under a 
bailment contract.  

Basically, the Model 264 was an updated and modernized P-26.  It 
differed from the P-26 in having fully-cantilever wings and a 
retractable undercarriage.  The undercarriage was similar to that 
which appeared on the Monomail, in which the main landing gear wheels 
retracted backwards about halfway into the wings.  The fuselage and 
the tail unit were basically the same as those of the P-26.  The 
engine was the tried and true Pratt & Whitney R-1340 Wasp air-cooled 
radial, basically the same type of engine which powered the P-26.  The 
aircraft had the same armament as did the P-26A, namely one 0.30-cal 
and one 0.50 cal machine guns mounted in the fuselage sides and firing 
between the cylinder heads of the radial engine.  

The first Model 264 to leave the Boeing factory featured a a narrow 
sliding cockpit enclosure that was essentially a transparent 
continuation of the pilot's oversize protective headrest all the way 
to the windshield frame.  The engine was the Pratt & Whitney R-1340-31 
Wasp of 550 hp, essentially identical to the engine which powered the 
engine.  However, the radial engine was enclosed in a full NACA 
cowling rather than being surrounded by the narrow Townend ring that 
was used on the P-26.  

The airplane made its maiden flight on January 20, 1934 and was flown 
to Wright Field for Army testing 5 days later.  The plane was 
originally tested by the Army on a bailment contract under the 
experimental military designation of XP-940.  During testing, the 
XP-940 achieved a maximum speed was 220 mph at 10,000 feet.  The gross 
weight was 3814 pounds.  

Upon testing of the XP-940, the Army decided on June 29, 1934 to buy 
it and its two sister ships.  The pursuit designation of P-29 was 
assigned.  In the meantime, the XP-940 had been returned to the 
factory in March for modifications.  The Army did not like the narrow 
cockpit enclosure, feeling that it restricted pilot vision too much.  
Consequently, Boeing replaced the narrow sliding cockpit enclosure by 
a standard open cockpit installation, but the distinctive long 
headrest that extended all the way to the tail was retained.  The 
engine was replaced by a 600 hp Pratt & Whitney R-1340-35.  The full 
NACA engine cowling that had been originally used was replaced by a 
drag ring similar to that which appeared on the P-26A.  

The modified XP-940 was returned to the Army in April of 1934.  The 
newly-configured plane flew for the first time on June 4, 1934.  Later 
that June, when the Army purchased the airplane outright, it was 
assigned the designation YP-29A and given a serial number of 34-24.  
It eventually became just plain P-29A after an engine change to a 600 
hp Pratt & Whitney R-1340-27 in place of the R-1340-35.  

The cleaner design of the YP-29A resulted in a plane which was 16 mph 
faster than the P-26A, but the greater weight cut down on the ceiling 
and the maneuverability, and the Army cancelled an intended P-29A 
order.  The three prototypes were subsequently used strictly for 
experimental purposes.  

As mentioned earlier, the military was displeased with the narrow 
cockpit enclosure of the XP-940.  The second Model 264 ordered by the 
Army was completed with a large and roomy glasshouse enclosure around 
the cockpit.  In addition, the tailwheel was housed in a different 
fairing.  The engine was the 600 hp Pratt and Whitney R-1340-35, 
enclosed in an antidrag ring.  The plane was delivered to the Army on 
September 4, 1934 under the designation YP-29 with a serial number of 
34-23.  Despite its earlier Army designation and serial number, it was 
actually the second Model 264 to fly.  Weights were 2509 lbs. empty, 
3518 lbs. gross.  Maximum speed was 250 mph at 10,000 feet.  Initial 
climb was 1600 feet per minute.  Service ceiling was 26,000 feet, and 
absolute ceiling was 26,700 feet.  Range was 800 miles.  This new 
cockpit enclosure satisfied the requirement for pilot protection at 
250 mph operating speeds.  Nevertheless, the landing speed of the 
YP-29 was considered too high for Army operational use.  

Because of the increased landing speed of the new monoplane design, 
the YP-29 was returned to the factory for the installation of wing 
flaps.  Following service testing by the Army and Boeing, which 
included trials with controllable pitch propellers, the service test 
designation was dropped and changed to plain P-29 after the engine was 
changed to a Pratt & Whitney R-1340-39.  

The third Model 264 was completed as YP-29B with an open cockpit 
configuration similar to that of the YP-29A.  The serial number was 
34-25.  It was delivered to the USAAC on October 11, 1934.  The only 
outward differences between it and the YP-29A were the addition of a 
one-piece wing flap similar to that of the YP-29, an additional one 
degree of dihedral in the wing, and an oleo tail wheel assembly 
similar to that of the YP-29.  The YP-29B was sent to Chanute Field in 
Illinois for service testing.  It was eventually redesignated just 
plain P-29B.  

Sources: 

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

  The American Fighter, Enzo Angellucci and Peter Bowers, Orion Books, 
  1987.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548