Subject: Number Fifty-One in the Series--North American P-51 Mustang (5 of 10)

From: [email-masked]
Date: 12 Feb 93 17:56:45 GMT

>From [email-masked]

On April 30, 1942, Ronald W. Harker, a test pilot for the British 
Rolls-Royce engine manufacturer, took a brief hop in a RAF Mustang at 
the airbase at Duxford.  Like lots of other pilots, he was highly 
impressed with the Mustang.  It was 30 mph faster than the Spitfire VB 
at similar power settings and had nearly twice the range.  Upon 
landing, he is reported to have said that the airplane would be a 
natural for the new Merlin 60 series of engines that Rolls Royce was 
just beginning to produce.  

Rolls Royce management immediately jumped into action.  They requested 
that three Mustangs be loaned to them so that they could fit them with 
Merlins.  Rolls Royce studied various Merlins, including the 
single-stage Mk XX and the two-stage Mk 61.  The two-stage Merlin was 
the better choice because of its far superior high-altitude 
performance.  The Merlin Mk 61 engine crankshaft was geared to two 
supercharger blowers stacked in series.  Because of the rapid 
compression of air, the temperature of the air after it passed through 
both stages of the supercharger increased by 200 centigrade degrees.  
In order to lower this temperature and thus increase the mass flow of 
the air entering the engine, an intercooler was added, requiring an 
extra radiator.  After much thought, it was decided to mount the extra 
radiator under the nose, in the same duct as the ram inlet for the 
updraft carburetor.  

This conversion was authorized on August 12, 1942.  Four Mustang Is 
were allocated to the program (AM208, AL975, AM203, and AL963).  They 
were assigned the designation Mustang X.  The first Mustang X took to 
the air on October 12, 1942.  No two of these Mustang Xs were exactly 
alike, but they all featured small chin-type radiators underneath the 
engine and four-bladed propellers to absorb the extra power.  These 
Mustang Xs were to be kept busy throughout the rest of the war, 
testing various later marks of the Merlin engine.  

One of the more bizarre proposals considered by Rolls-Royce was the 
possible installation of a 2400 hp Rolls-Royce Griffon 63 engine 
mounted amidships in a Mustang airframe a la P-39 Airacobra, driving a 
contrarotating propeller via an extension shaft.  The cockpit was to 
be moved forward to a position well ahead of the wing.  It was 
anticipated that this modification would make it possible to achieve 
speeds as high as 500 mph.  A mockup of this configuration was 
carefully prepared, but the concept was abandoned before work could 
proceed any farther.  

Meanwhile, in May of 1942, Rolls-Royce had informed Major Thomas 
Hitchcock, US military attache in London, that they planned to convert 
Mustang airframes to the Merlin engine.  It just so happened that 
Major Hitchcock had been thinking of just this idea himself.  He 
passed the word along to Wright Field and to North American Aviation.  
At this time, negotiations were taking place with the Packard Motor 
Car Company of Detroit for license manufacture in the United States of 
the new Merlin engine with the two-stage supercharger.  On July 25, 
1942, North American was authorized to convert two Mustangs to Merlin 
65 engines imported from England.  These aircraft were considered 
sufficiently different from the existing Mustang that they were given 
a new designation--XP-78.  

NAA selected two P-51s from the batch of Mustang IAs that had been 
repossessed from the RAF by the USAAF.  Their serial numbers were 
41-37350 and 41-37421.  NAA gave the project the company designation 
NA-101.  The designation of these two aircraft was changed to XP-51B 
while the work was progressing.  Although the early work by 
Rolls-Royce in conversion of Mustangs to the Merlin engine provided 
valuable insight to North American engineers, the British engine 
manufacturer did not directly participate any further in the project.  

The North American engineers moved the carburetor air intake from 
above to below the nose in order to accommodate the Merlin's updraft 
induction system.  The intercooler radiator was added to the radiator 
group already located inside the scoop underneath the rear fuselage, 
and the ventral radiator group was made noticeably deeper than before 
and had a sharp-angled inlet standing more than two inches away from 
the underside of the fuselage.  The matrix and door arrangement of the 
ventral radiator system were modified.  Instead of the oil cooler 
being situated in the center of a circular coolant radiator, it was 
relocated to the front of the duct and provided with its own ventral 
exit door.  Further downstream, in a greatly enlarged duct, was the 
huge rectangular coolant matrix, with a much bigger exit door at the 
rear.  The airframes were strengthened in order to make full use of 
the increased power available.  New ailerons were fitted and the 
underwing racks were increased in capacity to take two 1000-lb bombs 
or their equivalent weight in drop tanks.  A new four-bladed Hamilton 
Standard hydromatic paddle-bladed propeller was fitted.  Provisions 
for fuselage- mounted guns were totally eliminated, plans being made 
for four 0.50-in machine guns mounted exclusively in the wings.  

The first XP-51B was flown by Bob Chilton on November 30, 1942.  It 
was initially flown without armament.  The performance improvement was 
nothing short of astounding.  The XP-51B achieved a level speed of 441 
mph at 29,800 feet, over 100 mph faster than the Allison-engined P-51 
at that altitude.  At all heights, the rate of climb was approximately 
doubled.  

The USAAF now finally had an aircraft which could compete on equal 
terms with the Fw 190 and the later models of the Bf 109.  The USAAF 
was finally fully sold on the Mustang, and a letter contract for 2200 
P-51Bs was issued.  The engine was to be the Packard V-1650-3, based 
on the Merlin 68.  All airframes were to be manufactured by North 
American at their factory in Inglewood, California and at a completely 
new plant built in great haste at Dallas, Texas.  Inglewood-built 
Mustangs were designated P-51B, Dallas-built Mustangs were designated 
P-51C.  These aircraft were almost identical, and can generally be 
distinguished only by serial number.  

The first P-51B flew on May 5, 1943, and the first P-51C flew on 
August 5 of that year.  Inglewood built 1988 P-51Bs and Dallas built 
1750 P-51Cs.  The P-51Cs on the 1942 and 1943 budgets were given the 
company designation NA-103.  1350 NA-103s were built.  Texas-built 
aircraft in the 1944 budget were designated NA-111.  

Initially, the P-51B and C had the Packard V-1560-3 engine rated at 
1400 hp for takeoff and 1450 hp at 19,800 feet and carried four 
0.50-inch machine guns with a total of 1260 rounds.  There were four 
hundred P-51B-1-NAs and 250 P-51C-1-NTs built.  

800 P-51B-5-NAs were built, all of them powered by the V-1650-3.  In 
the pursuit of still more range, a P-51B was experimentally fitted 
with an extra 85 US gallon self-sealing fuel tank behind the pilot's 
seat, bringing the total fuel to 419 US gallons (including 2 drop 
tanks).  This extra fuel made the directional stability of the Mustang 
quite poor, so that the pilot would have to spend the first hour or so 
concentrating on keeping his airplane pointed in the right direction 
until this new tank was finally empty.  The last 550 P-51B-5-NAs were 
fitted with this extra tank, becoming P-51B-7-NAs.  Some earlier 
P-51Bs and Cs were modified in the field to accommodate this tank.  In 
service, however, the directional instability caused by the presence 
of a full fuel tank behind the pilot's seat was a hazard for new or 
inexperienced pilots, and the tank was usually restricted to 65 US 
gallons.  This extra tank, nevertheless, still made a crucial 
difference in combat radius, and it was standard equipment in all 
future production versions.  

With the introduction of the P-51C-5-NT onto the Dallas production 
line, the Packard V-1560-7 engine was adopted as standard.  It offered 
1450 hp for take off and a war emergency rating of 1695 hp at 10,300 
feet.  Maximum speed at 20,000 feet was reduced from 440 to 435 mph, 
but increased from 430 to 439 mph at 25,000 feet.  398 P-51B-10-NAs, 
390 P-51B-15-NAs, and 1350 P-51C-10-NTs were built, all powered by the 
V-1650-7 engine.  

A total of 91 aircraft from the Block-10 production lot (71 
P-51B-10-NAs and 20 P-51C-10-NTs) were fitted with two oblique K24 
cameras, or a K17 and a K22, to become F-6C photo aircraft.  Most of 
these aircraft retained their guns.  

The first combat unit equipped with Merlin-powered Mustangs was the 
354th Fighter Group, which reached England in October of 1943.  The 
354th flew their first cross-Channel sweep mission on December 1, 
1943, and scored their first victory on a mission to Bremen on 
December 16.  However, inexperienced pilots and ground crews and 
numerous technical problems limited operations with the P-51B/C until 
about eight weeks into 1944.  From the early spring of 1944, the 
Merlin-powered Mustang became an important fighter in the ETO.  

In March of 1944, Merlin-powered Mustangs accompanied B-17 Fortress 
and B-24 Liberator bombers all the way on a 1100-mile round trip to 
Berlin.  The ability of escort fighters to accompany bomber formations 
all the way to their targets and still effectively counter 
intercepting Luftwaffe fighters after jettisoning their nearly empty 
drop tanks caused the German defenses no end of problems, and added 
considerable impetus to the American daylight bombing offensive.  

Most of the P-51B/Cs were assigned to the 8th and 9th Air Forces in 
England, with a lesser number with the 12th and 15th USAAF in Italy.  
The P-51B/C remained the prime Mustang variant in service from 
December 1943 until March of 1944, when the bubble-topped P-51D began 
to arrive.  However, P-51B/C fighters remained predominant until the 
middle of 1944, and remained in combat until the end of the war in 
Europe even after the arrival of large numbers of P-51Ds.  Even as 
late as the last month of the war, 1000 out of the 2500 Mustangs 
serving in the ETO were of the P-51B/C variety.  

P-51Bs and Cs were assigned to the following fighter groups in the 
European Theatre: 

	4th Fighter Group, 8th Air Force 
	20th Fighter Group, 8th Air Force 
	335th Fighter Group, 8th Air Force 
	339th Fighter Group, 8th Air Force 
	352nd Fighter Group, 8th Air Force 
	357th Fighter Group, 8th Air Force 
	359th Fighter Group, 8th Air Force 
	361st Fighter Group, 8th Air Force 
	479th Fighter Group, 8th Air Force 
	354th Fighter Group, 9th Air Force 
	363rd Fighter Group, 9th Air Force 
	52nd Fighter Group, 12th Air Force 
	325th Fighter Group, 15th Air Force 
	31st Fighter Group, 15th Air Force 
	332nd Fighter Group, 15th Air Force 

Perhaps the best known P-51B aircraft is "Shangri La", a P-51B-5-NA 
(Ser No 44-6913) flown by the Fourth Fighter Group ace Don Gentile.  

The Merlin-powered Mustang entered service in the China-Burma-India 
(CBI) theatre in September 1943.  These aircraft were assigned to the 
23rd and 51st Fighter Groups of the 5th Air Force.  Early in 1944, the 
311th Fighter Group of the 10th Air Force saw action in Burma with its 
Mustangs, flying in support of airborne troops attacking Japanese 
lines of communication.  The top Mustang ace of the CBI theatre was 
Major John C. "Pappy" Herbst, with 18 kills.  

In late 1942, a deal was worked out between Britain and the USA in 
which Spitfire VBs would be transferred to the 8th Air Force in 
England, mainly for use as fighter-trainers.  This cleared the way for 
Lend-Lease supplies to continue of the new Mustang model to the RAF.  
The RAF equivalent to the USAAF P-51B/C was the Mustang III.  The RAF 
ultimately received 274 P-51Bs and 626 P-51Cs.  RAF serials were 
FB100/FB124, FB135/FB399, FR411, FX848/FX999, FZ100/FZ197, 
HB821/HB962, HK944/HK947, HK955, HK956, KH421/KH640, SR406/SR438, and 
SR440.  Serial numbers FX848, 849, 907, 909, 910, 911, 913, 914, 915, 
916, 918, 927, 928, 932, 948 were handed back to the USAAF upon 
arrival in Britain.  HK944/947, 955, 956 were ex-Twelfth USAAF 
aircraft.  KH490 crashed in the USA before delivery.  Serial numbers 
SR406/438 and SR440 were a mixed bag of P-51Bs and Cs delivered to the 
RAF from the USAAF--US serial numbers were respectively 43-12162, 
43-12407, 43-12412, 43-12473, 43-12484, 43-12427, 43-70114(?), 
43-12189, 43-12177, 43-7039, 43-6831, 43-12155, 43-12188, 43-12456, 
43-12480, 43-12399, 42-10663(?), 42-106683, 42-106630, 42-106687, 
43-7071, 43-7144, 43-5595, 43-7171, 43-6829, 43-12420, 43-7152, 
43-7135, 42-103209, 42-106478, 42-106431, 43-7007, 43-12420, 43-7159.  
(Question marks denote serial numbers which are probably erroneous). 

A total of 59 Mustang IIIs were diverted to the Royal Australian Air 
Force and to other Allied air arms.  

After these Mustang III aircraft had been delivered to England, the 
RAF decided that the hinged cockpit canopy offered too poor a view for 
European operations.  A fairly major modification was made in which 
the original framed hinged hood was replaced by a bulged Perspex 
frameless canopy that slid to the rear on rails.  This canopy gave the 
pilot much more room and the huge goldfish bowl afforded a good view 
almost straight down or directly to the rear.  This hood was 
manufactured and fitted by the British corporation R. Malcolm & Co., 
and came to be known as the "Malcolm Hood".  This hood was fitted to 
most RAF Mustang IIIs, and many USAAF P-51 received this modification 
as well.  

The first RAF base to receive Mustang IIIs was at Gravesend in Kent.  
The Mustang III initially equipped No. 65 Squadron in late December 
of 1943, followed by No. 19 Squadron in March of 1944.  Later the Mk.  
III also equipped Nos 64, 65, 66, 93, 94, 112, 118, 122, 126, 129, 
165, 234, 237, 241 249, 250, 260, 268, 306, 309, 315, 316, 345, 430, 
441, 442, and 516 Squadrons and No.  541 Squadron of RAF Coastal 
Command.  These units included four Polish squadrons (306, 309, 315, 
316), three RCAF, and one Free French.  

The new RAF Mustang IIIs began operations late in February 1944, 
escorting US heavy bombers as well as both US and RAF medium bombers.  

Numerous RAF Mustang IIIs were diverted to the interception of V-1 
"buzz-bombs".  Some of them were "souped up" by using a special 
high-octane fuel and internal engine adjustments in order to increase 
the intake manifold pressure and made it possible to achieve a speed 
of 420 mph at 2000 feet.  Since the typical V-1 flew at 370 mph, this 
made the "souped-up" Mustang very useful against these weapons.  

About 100 P-51Bs and Cs were supplied to the Chinese Air Force in 
1943-44.  

During late 1944, French units acquired some F-6Cs and began to 
operate them over Germany in January of 1945 on photo-mapping 
missions.  

The last P-51B passed out of service in 1949, having been 
re-designated F-51B in 1948.  

Specs of P-51B-1-NA: 

One 1620 hp Packard Merlin V-1650-3 twelve cylinder Vee liquid-cooled 
engine.  Maximum speed was 388 mph at 5000 feet, 406 mph at 10,000 
feet, 427 mph at 20,000 feet, 430 mph at 25,000 feet, 440 mph at 
30,000 feet.  Range on internal fuel was 550 miles at 343 mph at 
25,000 feet, 810 miles at 253 mph at 10,000 feet.  With maximum 
external fuel, maximum range was 2200 miles at 244 mph.  An altitude 
of 5000 feet could be attained in 1.8 minutes, 10,000 feet in 3.6 
minutes, 20,000 feet in 7 minutes.  Service ceiling was 42,000 feet.  
Weights were 6840 lbs empty, 9200 lbs normal loaded, 11,200 lbs 
maximum loaded.  Wingspan was 37 feet 0 1/4 inches, length was 32 feet 
3 inches, height 8 feet 8 inches, and wing area was 233 square feet.  

Specs of P-51C-10-NT: 

One 1695 hp Packard Merlin V-1650-7 twelve cylinder Vee liquid-cooled 
engine.  Maximum speed was 395 mph at 5000 feet, 417 mph at 10,000 
feet, 426 mph at 20,000 feet, 439 mph at 25,000 feet, 435 mph at 
30,000 feet.  Range on internal fuel was 955 miles at 397 mph at 
25,000 feet, 1300 miles at 260 mph at 10,000 feet.  With maximum 
external fuel, maximum range was 2440 miles at 249 mph.  An altitude 
of 5000 feet could be attained in 1.6 minutes, 10,000 feet in 3.1 
minutes, 20,000 feet in 6.9 minutes.  Service ceiling was 41,900 feet.  
Weights were 6985 lbs empty, 9800 lbs normal loaded, 11,800 lbs 
maximum loaded.  Wingspan was 37 feet 0 1/4 inches, length was 32 feet 
3 inches, height 8 feet 8 inches, and wing area was 233 square feet.  

Serial numbers of P-51Bs: 

43-12093/12492 		North American P-51B-1-NA Mustang 
43-6313/7112 		North American P-51B-5-NA Mustang 
43-7113/7202 		North American P-51B-10-NA Mustang 
42-106429/106540 	North American P-51B-10-NA Mustang 
42-106541/106738 	North American P-51B-10-NA Mustang 
42-106739/106978 	North American P-51B-15-NA Mustang 
43-24752/24901 		North American P-51B-15-NA Mustang 

Serial numbers of P-51Cs: 

42-102979/103328 	North American P-51C-1-NT Mustang 
42-102979/103328 	North American P-51C-1-NT Mustang 
42-103329/103778 	North American P-51C-5-NT Mustang 
42-103779/103978 	North American P-51C-5-NT Mustang 
44-10753/10782 		North American P-51C-10-NT Mustang 
44-10783/10817 		North American P-51C-11-NT Mustang 
44-10818/10852 		North American P-51C-10-NT Mustang 
44-10853/10858 		North American P-51C-11-NT Mustang 
44-10859/11036 		North American P-51C-10-NT Mustang 
44-11037/11122 	 	North American P-51C-11-NT Mustang 
44-11123/11152 		North American P-51C-10-NT Mustang 
43-24902/25251 		North American P-51C-10-NT Mustang 

Although literally hundreds of P-51Ds are still in existence today 
(many of them still flying), very few P-51B/C fighters have survived 
to the present, even in museums.  Ed Maloney's Air Museum in Ontario, 
California, the National Air Museum, and the Movieland Museum of the 
Air are reported to have P-51B/C aircraft on display.  No others are 
known to exist.  Anyone have further details? 

Sources:

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

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

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

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

  Fighting Mustang: The Chronicle of the P-51, William N. Hess, 
  Doubleday, 1970.  

  Classic Warplanes: North American P-51 Mustang, Bill Gunston, Gallery 
  Books, 1990.  

  Famous Fighters of the Second World War, Volume I, William Green, 
  1967.  

  The North American P-51B and C Mustang, Richard Atkins, Aircraft in 
  Profile, Doubleday, 1969.  

  British Military Aircraft Serials, 1912-1969, Bruce Robertson, Ian 
  Allen, 1969.  

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