From: Joseph F Baugher <jfb@ihlpl.att.com>
Subject: Number Forty in the Series--the Curtiss P-40
Keywords: P-40N, last in the line
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Thu, 7 Jan 1993 17:40:22 GMT


From Joseph F Baugher <jfb@ihlpl.att.com>

By the summer of 1943, the performance of the P-40 Warhawk was leaving 
much to be desired, especially in comparison to the later types such 
as the P-38, P-47, and P-51 which were beginning to come into service.  
The P-40N version (company designation Model 87V, 87W) was introduced 
at this time in an effort to improve the capabilities of the basic 
design and thus avoid interrupting Curtiss production lines by having 
the company introduce an entirely new type.  A new lightweight 
structure was introduced, two of the six wing-mounted guns were 
removed, smaller and lighter undercarriage wheels were installed, head 
armor was reintroduced, and aluminum radiators and oil coolers were 
installed.  

The first 1500 examples of this new Warhawk line were to have been 
delivered as P-40Ps powered by Merlin engines, but shortages of the 
Packard-built Merlin caused this order to be cancelled and the P-40N 
with the 1200 hp Allison V-1710-81 engine to be substituted in its 
place.  

Even though in 1943 the Warhawk was rapidly becoming obsolescent, the 
P-40N became the version that was most widely built--5220 examples 
rolling of the production lines.  

There were several production blocks of the P-40N, which differed from 
each other as follows: 

The first production block was the P-40N-1-CU.  It appeared in March 
of 1943, still powered by the Allison V-1710-81 engine, but with 122 
gallons of internal fuel and a generally lighter structure than its 
predecessors.  With weight reduced to 6000 pounds empty, 7400 pounds 
gross, and 8850 pounds maximum, the N-1 was the fastest P-40 service 
variant and was intended for high altitude combat.  Maximum speed was 
378 mph at 10,500 feet and service ceiling was 38,000 feet.  An 
altitude of 15,000 feet could be attained in 6.7 minutes.  Four 
hundred P-40N-1-CUs were built.  

The P-40N-5-CU variant introduced a modified cockpit canopy with a 
frameless sliding hood and a deeper, rectangular aft transparent 
section to improve the rearward view.  This cockpit canopy was 
retained for all the rest of the production blocks of the N version.  
The N-5 version restored the full six-gun wing armament, since pilots 
had complained that four guns were insufficient.  Underwing racks were 
fitted for bombs or drop tanks, increasing external stores capacity to 
1500 pounds.  The new heavier gross weight of 8350 pounds limited top 
speed to 350 mph at 16,400 feet and service ceiling to 31,000 feet.  
An altitude of 14,000 feet could be attained in 7.3 minutes.  Range 
was 340 miles with a 500-pound bomb underneath the fuselage.  Three 
drop tanks promised a ferry range of up to 3100 miles at 198 mph.  The 
P-40N-6-CU was the designation given to N-5s modified in the field and 
fitted with reconnaissance cameras in the fuselage.  

The P-40N-10-CU production block aircraft were winterized.  

The P-40N-15-CU production block aircraft differed in having the 
battery located forward of the firewall and new landing lights.  

The P-40N-20-CU introduced the V-1710-99 engine, which was simply an 
-81 powerplant with an automatic engine control unit.  

The P-40N-25-CU differed only in having a revised instrument panel.  
The P-40N-26-CU was the designation given to N-5s fitted with 
reconnaissance cameras in the fuselage.  Three P-40N-25-CUs were 
converted as two-seat trainers under the designation RP-40N-26-CU.  

On February 14, 1944, another thousand Warhawks were ordered, broken 
down into a batch of 500 N-30s and 500 N-35s.  They were similar to 
the N-25 except for valve and electrical system changes.  The N-30 had 
modifications to the lubrication system.  Twenty-two N-30s were 
converted to two-seat trainers as P-40N-31-CU.  Seventy were converted 
to P-40R-1 trainers in 1944.  

The P-40N-35-CU featured changes in the carburetor, the instruments, 
and the lighting.  

As late as June 30, 1944, when the front-line equipment of all major 
air forces had far outpaced the potential of the P-40 series, an order 
for yet ANOTHER 1000 Warhawks was placed.  This was the P-40N-40-CU 
production block.  However, this order was later cut back to 220 
aircraft.  The N-40 was powered by the V-1710-115 engine of 1360 hp 
and featured metal-covered ailerons.  The N-40 variant dispensed with 
the camouflage finish starting with 44-47860.  It included improved 
non-metallic self-sealing fuel tanks, new radio and oxygen equipment, 
and flame-damping exhausts.  

The last production Warhawk was a P-40N-40-CU which left the assembly 
line on November 30, 1944, being the 13,738th P-40 built.  

One P-40N was experimentally fitted with a bubble canopy and was 
unofficially designated XP-40N.  

The following spec refers to the P-40N-15-CU: 

One 1200 hp Allison V-1710-81 twelve-cylinder liquid-cooled engine.  
Maximum speed 208 mph at 5000 feet, 325 mph at 10,000 feet, 343 mph at 
15,000 feet.  Maximum climb rate was 2120 feet per minute at 5000 
feet, 2230 feet per minute at 10,000 feet.  An altitude of 10,00 feet 
could be attained in 4.7 minutes, 20,000 feet in 8.8 minutes.  Service 
ceiling was 31,000 feet.  Range was 750 miles at 10,000 feet (clean).  
With one 62.4 Imp gal drop tank, range was 1080 miles.  Weights were 
6200 pounds empty, 8350 pounds loaded, 11,400 pounds maximum.  
Dimensions were wingspan 37 feet 4 inches, length 33 feet 4 inches, 
height 10 feet 7 inches, wing area 236 square feet.  

Many of the P-40Ns were shipped to Allied air forces under Lend-Lease, 
and comprised the majority of the 1097 P-40s sent to the USSR.  Most 
of their operational flying took place in the Pacific in 
fighter-bomber or escort roles, most of them flown by RAF, RAAF, and 
RNZAF pilots.  In USAAF service, the P-40N was relegated largely to 
training roles, as later types such as the P-51 Mustang or the P-47 
Thunderbolt became increasingly available in quantity.  

586 P-4ONs were to be Kittyhawk IVs for Britain, but the first 130 
were diverted to the USSR.  The RAF Kittyhawk IV serials were as 
follows: 

FS270/399 (all diverted to the USSR) FT849/954 FX498/847 

Although the RAF evaluated the P-40Ns in the United Kingdom, they were 
employed solely abroad.  Most of the RAF Kittyhawk IVs were phased out 
of service early in 1945, but one RAF squadron continued to operate 
the Kittyhawk IV until the end of hostilities.  RAF squadrons equipped 
with the P-40N included Nos 112, 250, and 450.  

468 P-40Ns were sent to Australia.  There serials were as follows: 

P-40N-1-CU 	A29-415/419 
		A29-435/442 
		A29-461/472 
		A29-503/541 
		A29-559/563 
		A29-577/587 

P-40N-5-CU 	A29-542/558 
		A29-564/576 

P-40N-20-CU 	A29-600/704 

P-40N-25-CU 	A29-800/811 
		A29-819/828 

P-40N-30-CU 	A29-900/928 

P-40N-35-CU 	A29-1000/1079 

P-40N-40-CU 	A29-1100/1221 

These Kittyhawk IVs were primarily operated in the South-West Pacific 
campaigns as low-altitude fighter and ground attack aircraft.  Thew 
were progressively replaced by Mustangs and Spitfires during the last 
year of the war, but the Kittyhawks continued to serve with RAAF 
Squadrons 75, 78, and 80 until the end of hostilities.  

172 P-40Ns were supplied to New Zealand.  Their serials were as 
follows: 

NZ3120/3179 
NZ3182/3270 
NZ3272/3293 

35 P-40Ns were supplied to Canada.  Their serials were 846/880.  

41 P-40Ns were supplied to Brazil, where some served until 1958.  They 
were serialled in 1945 in the range 4020/4100.  One of them still 
survives there as a monument (USAAF serial 44-7700, Brazilian serial 
4064).  

An unspecified number were delivered to the Royal Netherlands East 
Indies Air Corps.  They flew them against the Japanese in the latter 
stages of the war, then against the nationalist rebels in Indonesia 
until February of 1949.  

A large proportion of the 2097 P-40s supplied to the Soviet Union were 
of the P-40N variety, but they were not very popular with the 
Russians, who considered them incapable of absorbing as much battle 
damage as the P-39 Airacobra.  

The USAAF serials of the P-40N production blocks were as follows: 

42-104429/104828 	Curtiss P-40N-1-CU Warhawk 
42-104829/105928 	Curtiss P-40N-5-CU Warhawk 
42-105929/106028 	Curtiss P-40N-10-CU Warhawk 
42-106029/106405 	Curtiss P-40N-15-CU Warhawk 
42-106406/106428 	Curtiss P-40N-20-CU Warhawk 
43-22752/24251 		Curtiss P-40N-20-CU Warhawk 
43-24252/24751 		Curtiss P-40N-25-CU Warhawk 
44-7001/7500 		Curtiss P-40N-30-CU Warhawk 
44-7501/8000 		Curtiss P-40N-35-CU Warhawk 
44-47749/47968 		Curtiss P-40N-40-CU Warhawk 
44-47969/48748 		Curtiss P-40N-40-CU Warhawk - contract cancelled.  

Those few P-40Ns still in service in 1948 with the USAAF were 
redesignated ZF-40N.  

There is a P-40N on display in the Champlin Fighter Museum at Mesa, 
Arizona.  I am unaware of its serial number.  It is painted in Chinese 
Flying Tiger colors.  

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 Kittyhawk I-IV, Ray Wagner, Aircraft in Profile, 
  Volume 6, Doubleday, 1969.

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


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