The P51 "Miss Stephanie"

The Manager
The Owner
The sound of the MERLIN (.waw, 63 Kb) Listen to the sound of a fly pass
Jack and Willy, 26Oct06 (mov, 11.6 Mb) Starting engine
Jack and Willy, 26Oct06 (mov, 3.61 Mb) Preparing to Taxy
Jack and Willy, 26Oct06 (mov, 9.67 Mb) Taking off
Willy at Stallion51, 21Feb13 (102.4 Mb) takeoff and roll
Willy at Stallion51, 21Feb13 (120.3 Mb) loops and landing
Willy at Stallion51, 21Feb13 ( 19.9 Mb) taxi back

The P51

In 1940, the British Purchasing Commission approached J.H. "Dutch Kindelberger, President of North American Aviation with a proposal to produce Curtis P-40 War Hawks, under license, for Great Britain. North American's designers, Raymond Rice and Edgar Schmued, responded with a counter proposal that they produce instead a brand new airframe that used the same Allison engine employed by the P-40.

The British agreed, under the condition that the new prototype be ready in an unheard of 120 days. North American, who had never even produced a fighter before, designed, manufactured and flew the NA-73x (P-51) prototype in a truly amazing 102 days.

Despite revolutionary features like a laminar flow wing, an under the fuselage radiator that provided additional "thrust" and a slick, aerodynamic shape, the early P-51A models were hampered by the poor high altitude performance and the mediocre top speed of the original Allison engine. Although good low level attack planes, they did not attract much interest on either side of the Atlantic.

All that changed when the British decided to test a Rolls Royce Merlin engine (used in the Spitfire) in a Mustang airframe. The rest, as they say, is history. Top speed leaped past 400 mph and high altitude performance was a revelation. The result was the P-51B, followed by re P-51C, both of which featured a Packard built Merlin and the flush patterned cage style canopy featured in our film.

The definitive wartime Mustang was the P-51 D, which introduced a new clear "bubble top" canopy (inspired by the British "Malcom Bubble") that offered an outstanding field of vision and a new 85 gallon fuel tank located behind the pilot's seat. The latter innovation was critical to the Mustang's success as a long range bomber escort fighter because it could now fly all the way from England to Berlin and back, something no other fighter could do at the time. It also meant that P-51's could roam far into enemy territory as a fighter/bomber to attack roads, airfields, rail lines, depots and communications to cripple the opposition's ability to respond

It was the Mustang's ability to place at or near the top in so many categories that made it an outstanding aircraft and a leading candidate for Best All Around Fighter of World War II: It was among the fastest piston engine planes of the war; it had an outstandingly high Mach number and strong construction so it could out dive opponents; it had a very good roll rate and could use it's "combat flaps" to turn inside many opponents; the P-51's great range meant it could fly farther and loiter longer in the battle zone than it's opponents, it's six 50 caliber machine guns packed plenty of punch and the mustang's rugged frame could absorb an unusual amount of damage. Though not "easy' to fly and requiring that the pilot pay attention, the Mustang was predictable, with good stall characteristics and was without any really nasty habits. About the only shortcoming of the P-51D was it's relatively heavy weight, which made it only a mediocre climber up to 20,000'. That deficiency would have been more of a draw back in an "Interceptor" than in the roles the Mustang was designed for, and that fault was corrected in the lightweight P-51H, which was produced too late in the War to see action. Ironically, it was the World War II workhorse, the P-51D, not the newer "H" model that saw heavy action in Korea because of an abundance of spare parts.

North American P-51D "Mustang" Vital Statistics
Single seat fighter Power plant one 1,695-hp (1186-kW) Packard V-1650-7 Merlin liquid-cooled 12 cylinder vee piston engine, four blade Hamilton Standard propeller
Maximum Speed: 437 mph (clean) 395 mph at 5000 ft (525m) Initial Climb: 3,745 ft (1059m) per minute Service Ceiling: 41,900 ft (13410m) Range: 2,600 miles (4184 km) with max fuel
Span: 37 ft 1 in ft (11.29m) Length: 32 ft 3 in (9.83m) Height: 13ft 8 in (4.17m) Wing Area: 235 sq ft (21.83m2) Weights: Empty: 7,125 lb (3232 kg) Max. Take-off: 11,600 lb (5262 kg)

6 X 0.5 (12.7mm) Browning machine guns Bomb Load 2 X 500 lb (1818 kg) bombs, H149 8 X 5-in (127mm) HVAR rockets

TP-51 D:
two-seat trainer version of P-51D, Four 0.5-in wing guns Production: 10 built in Dallas, also several conversions of existing aircraft

Redesignated TF-51D in 1948

The Rolls-Royce and Packard built Merlin engine is universally acknowledged as one of the finest piston engines that has ever been manufactured. Remarkably, over 50 years have elapsed since the last Merlin engine rolled off the production line, yet it is still in widespread daily use in warbird aircraft, not least of all the P-51 Mustang, Just as North American Aviation would never have envisioned their Mustangs would still be flying, Rolls-Royce probably never considered that their beautiful Merlin powerplant would still be in "front line service" in the 21st Century.

The overall success of this famous engine is built on one simple fact. By employing technology many years ahead of its time, fueled by the urgency of war, Rolls-Royce produced a powerplant that still has no equal as a piston fighter powerplant.

Ironically, but not untypical of British industrial practice in the 20th Century, the British government, through the Air Ministry, declined to fund a new engine despite the Schneider Trophy success of the early 1930's. In December 1932 the Rolls-Royce board, in the true spirit of British entrepreneurship, elected to finance the engine themselves as a private venture. Thus, early development of the engine were designated P.V.12 No one could have envisioned that this step would contribute so significantly to the allied victory in the air.

Few would dispute the Battle of Britain was won as a result of the Merlin II and III. Another significant development was the brilliant discovery, by a scientist at the Royal Aeronautical Establishment, Miss Shilling, who designed a most simple system - a small metal diaphragm in the float chamber of the carburetor - that enabled the engine to continue running in negative G situations in combat.

1938 saw Stanley Hooker join Rolls-Royce. It was Hooker who concentrated on the development of the Merlin's supercharger. Even modern day Merlin rebuilders will tell you the engine's supercharger is the finest of its type ever produced. Why? It improves the power envelope from 12,000 to 40,000 feet. This unit is at the heart of the engines remarkable performance over a significant altitude range.

At the beginning of World War II and the beginning of the Battle of Britain, every front line fighter aircraft was fitted with the Merlin. One of the main Luftwaffe tactics was low flying and the sea level power of the Merlin had to be enhanced as a result. Rolls-Royce achieved a 40% increase in power at sea level due to the supercharger development and this forced the Luftwaffe to fly higher to combat air superiority at low level. With the success of supercharger development the Merlin XX and Merlin 45 were introduced into the Spitfire and Hurricane and this enabled the Royal Air Force to maintain fighter superiority.

During the war years over 150,000 Merlin engines were manufactured in the U.K. and U.S.A. The Packard Motor Car Company undertook the latter and it was this version that was to power the legendary North American Mustang. However, unrecognized by many are the huge differences in the Packard built version. Packard manufactured some 57,000 Merlin engines, over a third of all Merlin production. From its earliest version the Merlin was clearly a precision, hand built work of engineering art constructed by some of the best British engineers. Even in its infancy the powerplant was built in small lots and had a string of design changes incorporated in an effort to squeeze performance and increase reliability in combat situations. The setback was this was not an engine designed for mass production, so in 1940, when the British Government turned to Packard for help with production of the Merlin some provisions had to be made.

In June 1940, Packard was requested to undertake the production of some 9000 Merlin XX engines. It took just three days for the company to respond positively but on that proviso that some modifications would be made to the powerplant to enable American accessories such as carburetors, fuel and vacuum pumps to be utilized. Packard then began the monumental task of organizing an engineering group to handle drawings and redesign for American production. In parallel Packard organized U.S. sources for carburetors, magnetos, spark plugs, and other accessories. Packard assigned some 200 personnel to the project and this included the draughtsmen who would undertake complete revisions of production drawings. At the outset the Packard engineers ran into problems, generally due to the fact that the engine was not designed for mass production. That the project was completed at all is testament to the determination and skill of those assigned the task.

After the end of hostilities in World War II, the Merlin saw extensive commercial service, particularly in Great Britain and Canada, extending well into the late 1950's. The Merlin 600 and 700 series were the subject of most testing and modification until as late as the 1960's. Since the Merlin emerged there have been three categories of operator in aviation. The use of the engine in battle tanks and boats is beyond the scope of this chapter. Broadly, these can be categorized as the originally Military operators, commercial (such as airlines) and right up to the present day, civilian warbird operators.

When commercial operators began using the Merlin cost became an important consideration. Most airline operators know the profit is in the last 20%. Civilian operators logged more TBO (time between overhaul) on their Merlin engines than military operators by a significant amount and consequently experienced associated problems military engineering teams never witnessed. Importantly, it was not cost effective to replace every component when it was worn past military service limits, so Rolls-Royce developed countless repair schemes and legal modifications to salvage otherwise unserviceable parts. Hence this extended the running life of parts in the engine. The repair schemes and modifications were the result of hours of re-engineering, development, and testing in the field. As these schemes became available for release, they had to have approval from Great Britain's Air Ministry. Many of these repair schemes are still in (legal) use today.

In the late 1950's the Mustang was released for sale to the general public. Most airframes sold had low times and consequently warbird owners enjoyed a period of three decades where engine overhaul posed little problem, and very often a spare engine (or two) had been acquired with the airframe anyway. Overhauls undertaken during this time were similar to military schedules where the engines were disassembled, cleaned, and reassembled. Though new seals and rings were sometimes installed major rework was just not necessary.

At the time of writing we calculate there are in the region of 500 Merlin engines (not counting museum static aeroplanes) in circulation amongst warbird operators and either installed in aircraft of held as spares. Some parts are becoming critical and there are a number of programs being undertaken to manufacture critical items to enable the Merlin to run for another 50 year, adding yet more achievements to what is already history.


Shortly after the war ended in 1945, the RCAF received 100 P-51D Mustangs from the USA. These were placed in service with the regular squadrons (until being replaced by Vampires and Sabres during 1949 and 1950) and also with auxiliary squadrons. The Mustangs served with the auxiliary units until 1956, when they had all been replaced by Vampires, and then by T-33s and Sabres. Some were also flown by the Central Experimental and Proving Establishment at Rockcliffe and some as fighter-bombers at the Canadian Joint Air Training Centre at Rivers, Manitoba.



  • 400 (Auxiliary) "City of Toronto" Toronto, Ont.
  • 401 (Auxiliary) "City of Montreal" St. Hubert, PQ
  • 402 (Auxiliary) "City of Winnipeg" Winnipeg, Man.
  • 403 (Auxiliary) "City of Calgary" Calgary, Alta.
  • 411 (Auxiliary) "County of York" Toronto, Ont.
  • 416 (Regular) "Lynx" Uplands, Ont.
  • 420 (Auxiliary) "City of London" London, Ont.
  • 421 (Regular) "Red Indian" Bagotville, PQ
  • 424 (Auxiliary) "City of Hamilton" Hamilton, Ont.
  • 438 (Auxiliary) "City of Weatmount" St. Hubert, PQ
  • 442 (Auxiliary) "City of Vancouver" Vancouver, B.C.
  • 443 (Auxiliary) "City of New Westminster" Vancouver, B.C
This Aircraft
Tail number: N 7098V s/n: 44-73871 Date Complete: 5-15-45
  Born as a single-seater P-51 D
US Air Force

73871 to RCAF as 9245.To civilian registry as N7098V.

RCAF December 6, 1950 to May 2, 1956, stationed with 416 Squadron in Trenton for the duration of its life with the RCAF.
UK?? Date unknown so far. Could have been left in a crate all the time.
Re-work as a TF-5 D 1989 to 1992 ????
Actual owner: 19xx to present
Stallion51 The P51 specialists.
Swiss Mustangs Interesting stories and pictures
Zenos Warbird Video Warbird site
US Air Force Warbirds by serial number
Royal Canadian Air Force RCAF Mustangs in Canada