| P-1 Hawk | |
|---|---|
 Curtiss P-1B Hawk | |
| General information | |
| Type | Fighter plane |
| Manufacturer | Curtiss Aeroplane and Motor Company |
| Primary user | United States Army Air Corps |
| Number built | 202 built as PW-8, P-1, P-2, P-3, P-5, AT-4 and AT-5 |
| History | |
| Manufactured | 1925–1929 |
| Introduction date | 27 April 1923 |
| First flight | January 1923 |
| Variants | Curtiss F6C Hawk Curtiss P-6 Hawk |
TheP-1 Hawk (Curtiss Model 34) is a 1920s open-cockpitbiplanefighter aircraft of theUnited States Army Air Corps. An earlier variant of the same aircraft had been designatedPW-8 prior to 1925.[1]
TheCurtiss P-1 Hawk was the firstUS Army Air Service aircraft to be assigned the "P" (Pursuit) designation which replaced seven designations for pursuit aircraft, including "PW" (for "Pursuit, Water-cooled engine"). The P-1 was the production version of the CurtissXPW-8B, an improved variant of thePW-8, 25 of which were operational with the Air Service's17th Pursuit Squadron[2]
In September 1923, the Army ordered production of thePW-8.[3] The PW-8 (Curtiss Model 33) had been developed from theR-6 racer and was acquired by the Air Service after a competition with theBoeing Model 15, designated the PW-9, to replace the existing Army fighter, theBoeing MB-3A. Although the PW-8 was faster than the PW-9 (both having top speeds in excess of 165 mph), it was otherwise outperformed by the Boeing plane, and its surface radiator cooling system, mounted on the upper and lower surfaces of the top wing for streamlining, was more difficult to maintain and vulnerable in combat. However, the Assistant Chief of the Air Service, Brigadier GeneralBilly Mitchell, agreed to purchase 25 PW-8s in return for assistance by Curtiss in making theDawn-to-dusk transcontinental flight across the United States.
The prototype of the P-1, theXPW-8B, came about when the Air Service, which had selected the BoeingPW-9 over the PW-8 as its main production fighter, asked Curtiss to modify the last of its three originalXPW-8 prototypes with wings resembling those of the PW-9. Curtiss designated the modified aircraft itsModel 34A and returned it to the Air Service for evaluation, from which the service ordered it into production as theP-1. The first production P-1, serial number 25-410, was delivered on August 17, 1925, and was followed in successive years by theP-1B andP-1C variants with improved engines. The newest P-1 variants remained in operational service until 1930.
The March 7, 1925 order for the P-1 also requested five aircraft with the more powerful 500 hp (373 kW) Curtiss V-1400engine installed. These were completed in January 1926. The first (SN 25-420) was then modified with aturbocharger mounted on the right side of thefuselage nose, and whose turbine was driven by engine exhaust; the craft was designatedXP-2.[4]
However, the Curtiss V-1400 engine did not perform up to expectations, with or without the supercharger, and so after a year in service, three of the standardP-2 Hawks had their engines replaced with theCurtiss D-12 and were consequently redesignated as P-1s. The fifth machine (25-243) received a Curtiss V-1570 Conqueror engine and became theXP-6.[4]
93 production P-1s were brought into service in the P-1, P-1A, P-1B, and P-1C variants. 52 other P-1s, variants P-1D, P-1E, and P-1F, were made by conversion of other Hawk variants, primarily AT-4 and AT-5 trainers.
TheP-3 Hawk was similar to the P-1 Hawk but with a radialR-1340-3 Waspradial engine. The first of the type, designatedXP-3A, was the last P-1A (serial 26-300). Originally intended to be powered by a 390 hp (291 kW) Curtiss R-1454, the engine was deemed unsatisfactory and the 410 hp (306 kW) Pratt & Whitney R-1340 engine substituted. A second XP-3A (serial 28-189) included acowling andspinner to reduce the drag due to the radial engine; entered in theNational Air Races of 1929, its speed of 186.84 mph (300.69 km/h) gave it second place in theThompson Trophy race.[4]
The remaining four aircraft were productionP-3As, but primarily used to service test thePratt & Whitney Wasp engine. In addition to the significant increase in drag, the radial engine also interfered with the pilot's view. Addition of aTownend ring cowling worsened the visibility problem, and had only a limited effect on speed.[4] It was also tested with various types of deep-chord NACA cowls.[5]
Two of the XP-3A aircraft were re-engined in 1929 and 1930 with thePratt & Whitney R-985-1 Wasp Junior engine. This aircraft was redesignated theXP-21. Tests were run with this aircraft, but it was never developed into a production aircraft, despite the designation.[6]
FiveP-5 Superhawks, similar to the P-1C but with a turbochargedCurtiss D-12F engine, were delivered in 1928. They had a top speed of 166 mph (267 km/h) at 25,000 ft (7,620 m), considerably higher than the maximum ceiling of the P-1A, but their low-level performance was inferior[7]
Two single-seat advanced trainer variants were placed into production, theAT-4 andAT-5A, usingWright-Hisso E /Wright-Hisso V-720 V-8 engines. The resulting performance degradation from these lower powered engines resulted in them being deemed dangerous to fly, even for experienced pilots. All were re-engined with Curtiss D-12D engines and returned to use as fighters, designatedP-1D andP-1F respectively. Five AT-4/XAT-5 test variants were re-classified asP-1E.[2]
A total of 202 PW-8, P-1, P-2, P-3, P-4, P-5, AT-4, and AT-5 airplanes were delivered.[8]
On June 23, 1924, taking off at 3:58 A.M., Armytest pilotFirst LieutenantRussell Maughan leftMitchel Field, New York, in PW-8 24-204, modified with additional fuel and oil tanks, made a dawn-to-dusk transcontinental flight across the US.[9] Refueling five times, he landed atCrissy Field, San Francisco, California, at 9:46 p.m., one minute before dusk, covering 2,670 mi (4,297 km) in 20 hours and 48 minutes. His flight time included four planned 30-minute stops atMcCook Field,Ohio;Saint Joseph, Missouri;Cheyenne, Wyoming; andSalduro Siding, Utah; and an unplanned stop inNorth Platte, Nebraska for additional fuel when a muddy field in Missouri did not permit him to take on a full load.[10] He also lost an hour at McCook to repair a broken fuel valve after an over-eager mechanic had over-torqued the valve, damaging it.
The original fifteenP-1s served in the 27th and 94th Pursuit Squadrons,1st Pursuit Group,Selfridge Field,Michigan. The first Hawk to serve with the Air Corps in quantity was theP-1A (17th, 27th, and 94th Pursuit Squadrons) beginning in 1925. In October 1928 the largest order of 33P-1s was made. These were delivered by April 1929 asP-1Cs.[5]
TheAT-4 andAT-5 trainer variants served with the 43rd Pursuit Squadron (School) atKelly Field, Texas.[5]
After concluding by the end of September 1928 thatwind tunnel tests of its "Cowling No. 10" not only cooled an engine more efficiently than leaving an engine'scylinders open to the air, but also that it reducedaerodynamic drag by a factor of 2.6 compared to any other cowling, the U.S.National Advisory Committee on Aeronautics (NACA) tested the cowling on an AT-5A borrowed from the Army Air Corps. The tests demonstrated that the cowling also significantly increased an aircraft's maximum speed, in the case of the AT-5A from 118 miles per hour (103 kn; 190 km/h) to 137 or 138 miles per hour (119 or 120 kn; 220 or 222 km/h). The cowling became known as theNACA cowling.[11]
While a total of 202 Hawks were built in the basic variants PW-8, P-1, P-2, P-3, P-5, AT-4 and AT-5, conversions resulted in 148 having a P-1 designation.
All variants increased in weight with each succeeding model, resulting in slight reductions in performance with each.
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A rebuilt Curtiss P-1 (manufacturer serial number 60) is on display at theNational Naval Aviation Museum. The aircraft is painted to represent F6C-1BuNo A6969, which crashed in 1929.[12]
Data from Curtiss Aircraft 1907–1947,[13] The Complete Encyclopedia of World Aircraft[2]
General characteristics
Performance
Armament
Related lists
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