NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/military/12137

Text File | 1992-12-22 | 13.7 KB | 252 lines

Newsgroups: sci.military
Path: sparky!uunet!gatech!hubcap!ncrcae!ncrhub2!ciss!law7!military
From: Joseph F Baugher <[e-mail]>
Subject: Number Forty in the Series--Curtiss P-40 (1 of 11)
Message-ID: <[e-mail]>
Keywords: XP-40, P-40A,B,C
Sender: [e-mail] (Sci.Military Login)
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Tue, 22 Dec 1992 17:28:15 GMT
Approved: [e-mail]
Lines: 239


From Joseph F Baugher <[e-mail]>


The P-40 was the best known Curtiss-Wright airplane of World War II.
It was also one of the most controversial fighters of the war.  It was
vilified by many as being too slow, lacking in maneuverability, having
too low a climbing rate, and being largely obsolescent by contemporary
world standards even before it was placed in production .  The
inadequacies of the P-40 were even the subject of a Congressional
investigation.  It gets regularly included on lists of the worst
combat aircraft of World War 2.

All of these criticisms certainly had some degree of validity, but it
is also true that the P-40 served its country well during the first
year of the war in the Pacific when very little else was available.
Along with the P-39 Airacobra, the P-40 was the only American fighter
available in quantity to confront the Japanese advance during the
first year of the Pacific War.  It helped stem the speed of the
Japanese advance until more modern types could be made available in
quantity.  The P-40 had no serious vices and was a pleasant aircraft
to fly, and, when flown by an experienced pilot who was fully aware of
its strengths and weaknesses, was able to give a good account of
itself in aerial combat.  The P-40 continued in production long after
later types were readily available, the numbers manufactured reaching
the third highest total of American World War II fighters, after the
Republic P-47 and the North American P-51.

The P-40 was obsolete by European standards even before the first
prototype flew, and it never did catch up.  Its Initial inadequacies
in the form of low firepower and lack of self-sealing fuel tanks or
armor were a reflection of mid-'thirties USAAC requirements which were
outmoded.  The P-40 had been developed as basically a low-altitude
close-support fighter under mid-1930s US tactical concepts which
envisaged more need for low-level ground support operations than for
high-altitude interceptions.  The military doctrine of the "ascendancy
of bombardment over pursuit" was dominant in 1937 when the P-40 first
appeared.  This doctrine assumed that the prospect of high-altitude
enemy air attack on the USA was extremely remote, with coastal defense
and ground attack in the defense of US territory being seen as the the
main tasks for any future fighter aircraft.  Low-altitude performance
and rugged construction received priority over high-altitude
capabilities.

During the war, the Senate Special Committee to Investigate the
National Defense Program (usually known as the "Truman Committee",
after its chairman, Senator Harry Truman of Missouri) criticized the
P-40 on several accounts, particularly on the original volume purchase
of an inadequate design and its continued production long after later
designs were readily available.  However, they finally concluded that
this was not brought about by any undue favoritism to Curtiss.

Some indication of the enormous P-40 production program undertaken by
Curtiss can be assessed by its claim on factory floor space and
manpower.  During 1941, the Curtiss Airplane Division expanded its
manufacturing area by 400 percent.  The total work force was 45,000.
This expansion included two new plants, one at Buffalo, New York and
the other at Columbus, Ohio, to supplement the original Curtiss plant
in St.Louis, Missouri.  At the peak of wartime production, the entire
Curtiss Airplane Division complex of factories was producing sixty
aircraft A DAY!

The origin of the P-40 can be traced back to the Curtiss P-36 (Model
75) fighter, which was powered by a radial, air-cooled engine.  A step
in the direction toward what was eventually to emerge as the P-40 was
the XP-37, which was described in an earlier post.  The P-36 design
was reworked to incorporate the Allison V-1710 liquid-cooled V-type
engine, resulting in the XP-37.  The XP-37 was equipped with a General
Electrc turbosupercharger, and featured a cockpit pushed very far to
the rear.  Thirteen YP-37 service-test aircraft were built, but
problems with the turbosupercharger caused the development of the P-37
to be abandoned in favor of a less complex and more straightforward
conversion of the P-36 for the Allison V-1710 engine.

Realizing that the radial-engined P-36A was at the limit of its
development, Curtiss designer Donovan Berlin got USAAC permission in
July 1937 to install a 1150 hp Allison V-1710-19 liquid-cooled engine
with integral supercharging in the 10th P-36A (Serial No 38-10).  This
project was given the company designation of Model 75P, and the USAAC
gave the project a new fighter designation, XP-40.

The XP-40 flew for the first time on October 14, 1938, with Edward
Elliot at the controls.  Armament was two 0.50-inch machine guns
located in the upper fuselage deck and synchronized to fire through
the propeller arc, standard armament for US pursuit aircraft at the
time.  Wing racks could be fitted for six 20-pound bombs.  A small oil
cooler was located beneath the pointed nose.  The air intake for the
single-stage supercharger was mounted on top of the engine cowling
between the two machine guns, but during tests it was replaced by a
long cowled intake duct which became characteristic of all the early
P-40 production models.  Initially, the coolant radiator was placed
under the fuselage aft of the wing, but it was gradually moved forward
until it finally ended up located underneath the extreme nose.  The
radiator intake was redesigned to include an oil cooler and two
coolers for the ethylene/glycol engine coolant.  The initial XP-40 had
a single exhaust port on each side of the fuselage, but in its final
form it had six separate exhaust ports on each side.  The initial
XP-40 had inherited from the P-36 a set of mainwheel fairing plates
which covered the mainwheels when they retracted into their wing
wells, but these were eventually deleted and replaced by two small
doors which closed over the wheel struts upon retraction.

The maximum speed of the XP-40 was 342 mph at 12,200 feet at a gross
weight of 6260 pounds.  This was faster than the Hawker Hurricane, but
slower than the Spitfire or the Bf 109E.  Empty weight was 5417
pounds, and fully-loaded weight was 6870 pounds.  Range was 460 miles
at 299 mph with 100 gallons of fuel.  With 159 gallons of fuel at 200
mph, a range of 1180 miles was claimed, almost twice that of the
contemporary Hurricane, Spitfire, and Bf 109E.  Wingspan was 37 feet 4
inches, wing area was 236 square feet, length was 31 feet 1 inch, and
height was 12 feet 4 inches.  The wingspan and wing area were to
remain the same throughout the entire history of the P-40 production
run.

In the late 1930s, the USAAC was planning to expand its force, and on
January 25, 1939.  manufacturers were invited to submit proposals for
pursuit aircraft.  The Army was still thinking in terms of
low-altitude, short-range fighters.  Among the contenders were the
Lockheed XP-38, the Bell XP-39, the Seversky/Republic XP-41 (AP-2) and
XP-43 (AP-4), and no less than three planes from Curtiss, the H75R,
XP-37, and XP-42.  Although the XP-40 could not match the performance
(especially at altitude) of the turbosupercharged types, it was less
expensive and could reach quantity production fully a year ahead of
the other machines.  In addition, the XP-40 was based on a
already-proven airframe that had been been in production for some
years.  Consequently, on April 26, 1939, the Army adopted a
conservative approach and ordered 524 production versions under the
designation P-40 (Curtiss Model 81).  At that time, it was the
largest-ever production order for a US fighter, and dwarfed the
service test orders placed that same day for YP-38 and YP-39 fighters.
A couple of weeks later, 13 YP-43s were also ordered.

The P-40 was similar to the final XP-40 configuration except for 1040
hp V-1710-33 (C15) engines and provisions for the mounting of one
0.30-inch machine gun in each wing.  Flush riveting was used to reduce
drag.  Armor, bulletproof windshields, and leakproof fuel tanks were
added in service.  The P-40 was a relatively clean design, and was
unusual for the time in having a fully retractable tailwheel.

The first flight of a P-40 (Ser No 39-156) was on April 4, 1940.
Maximum speed was 357 mph at 15,000 feet, service ceiling was 32,750
feet, and initial climb rate was 3080 feet per minute.  An altitude of
15,000 feet could reached in 5.2 minutes.  The length of the P-40 was
31 feet 8 3/4 inches, which became standard for all early models.
Weights were 5376 pounds empty, 6787 pounds gross, and 7215 pounds
maximum.

Deliveries of the P-40 to Army units began in June of 1940.  Three of
the P-40s were used for service testing, the USAAC contract making no
provisions for the standard practice of supplying YP models.

Foreign air forces were beginning to take notice of the P-40, and in
May of 1940, the Armee de l'Air of France placed an order for 140
H-81A (export model of the P-40).

Only 200 of the initial P-40 order were actually completed as P-40s.
Serials were 39-156/280 and 40-292/357.  The remaining 324 aircraft of
the order had their delivery deferred to enable Curtiss to expedite
the delivery of the 140 H-81As to France.  However, none of these
actually reached France before the Armistice in June 1940, and the
contract was taken over by the Royal Air Force as Tomahawk I.

16 P-40s were sent to the Soviet Union after the German invasion.

The P-40 lacked such things as armor for the pilot, self-sealing fuel
tanks, and a bulletproof windshield, so it was not considered as being
suitable for combat.  On October 22, 1942, the P-40s still in USAAF
service were ordered restricted from combat duty and were redesignated
RP-40.

The P-40A designation was skipped in the initial designation
assignments.  However, it was applied retroactively to P-40 Ser No
40-326 when it was converted to a camera-carrying photographic
reconnaissance model at Bolling Field in March of 1942.

The P-40B (Model H81B) differed from the P-40 in having an extra
0.30-inch machine gun in each wing.  The engine was still the
V-1710-33.  In September 1940, 131 P-40Bs were procured by the Army to
replace the deferred P-40s.  Serials were 41-5205/5304 and
41-13297/13327.  The first P-40B flew on March 13, 1941.  The P-40B
retained the same dimensions of the P-40, but weight was increased to
5590 pounds empty, 7326 pounds gross, and 7600 pounds maximum loaded.
Because of the additional weight, the P-40B had an inferior
performance to the P-40, maximum speed being 352 mph, service ceiling
being 32,400 feet, and initial climb rate being 2860 feet per minute.
Normal range was 730 miles, but a maximum range of 1230 miles could be
attained at the minimum cruise settings.

The export equivalent of the P-40B was the Tomahawk IIA (Model
H81-A2).  They differed from the American version by having the wing
guns replaced by 0.303-inch Brownings.  110 were produced for the RAF.
RAF serials were AH881/990.  23 of these planes were transferred to
the USSR, and one (AH938) went to Canada as an instructional airframe.

The initial P-40 order was finally completed with 193 P-40Cs (company
designation H81-B).  Serials were 41-13328/13520.  The first flight of
a P-40C was made on April 10, 1941.  The P-40C retained the 1150 hp
Allison V-1710-33 engine, but was fitted with a new fuel system with
134 gallons in new tanks with improved self sealing.  In addition,
provisions were made for a 52-gallon drop tank below the fuselage.
The P-40C had a SCR-247N radio instead of the SCR-283.  These
additions produced yet another upward crawl in the weight--the weights
for the P-40C were 5812 pounds empty, 7459 pounds gross, and 8058
pounds maximum loaded.  Consequently, the performance continued to
degrade.  Maximum speed was 345 mph at 15,000 feet.  Normal and
maximum ranges were 730 and 945 miles respectively.  Service ceiling
was 29,500 feet, and initial climb rate was 2650 feet per minute.
Dimensions were wingspan 27 feet 3 1/2 inches, length 31 feet 8 1/2
inches, height 10 feet 7 inches, wing area 236 square feet.

The export equivalent of the P-40C was the Tomahawk IIB (Model
H81-A2).  A total of 930 were built.  RAF serials were AH991/999 (all
to USSR), AK100/570 (36 to China), AM370/519 (64 to China), and
AN218/517.

100 of these planes, unofficially designated H81-A3, were transferred
to China where they were used by the American Volunteer Group--the
famous "Flying Tigers".  23 went to the USSR, and unspecified numbers
went to Turkey and Egypt.  The rest were used extensively by the RAF
and South African Air Force in the North African theatre.

Sources:

  War Planes of the Second World War, Fighters, Volume Four, William Green,
  Doubleday, 1964.

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

  United States Military Aircraft since 1909, Gordon Swanborough and Peter
  M. Bowers, Smithsonian Institution Press, 1989.

  Curtiss Aircraft, 1907-1947, Peter M. Bowers, Naval Institute Press, 1979.

  The Curtiss P-40 Tomahawk, Ray Wagner, Aircraft in Profile, Volume 2,
  Doubleday, 1965.

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road
          Naperville, Illinois 60566-7033.   [phone]