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F-51H

by Tom Cleaver

The true mark of greatness in an airplane is its capacity for further development far beyond its original concept. 

The Bf-109K-4 bore little more than a superficial resemblance to the Bf-109B; similarly, the Spitfire 24 bore virtually no resemblance to the Spitfire I; and the F-51H bore even less relation to a P-51A than the others did to their predecessors, who at least shared similar rear fuselage structures. The F-51H was a completely new development, bearing only a passing visual similarity to its predecessors.

The P-51B is the high-water mark for the original Mustang design; the P-51D was heavier without a commensurate gain in performance past an increase in armament and pilot visibility, and its handling was decidedly different than its lighter Merlin-powered predecessor, which was far more manoeuvrable.

In 1943, North American and the USAAF. both recognized that the original Mustang had passed its peak of development. The P-51D, at 11,000 pounds, was some 35 percent heavier than the original Mustang, with only a 25 percent increase in power. The desire was for increased speed, increased altitude, increased range and increased manoeuvrability. The solution was to go back to the drawing board, which Edgar Schmued and his team did under the overall direction of Lee Atwood.

The result was an airplane with a different wing that lost its characteristic "crank" due to the use of smaller wheels, a different, finer fuselage, and a structure that included plastics wherever possible. The first airplane to emerge from this was the XP-51F: to reduce drag compared to the P-51D, its most notable difference was a longer bubble canopy, as well as the low-drag wing. Armament was reduced to four .50 cal. machine guns, while overall fuel capacity was increased with two 105-gallon wing tanks. The net result was an airplane that weighed just over 9,000 pounds, capable of a 466 mph maximum speed with the same V-1650-7 Merlin of the P-51D, as compared to 425 mph for the earlier airplane. Three were built. Two more lightweights called the XP-51G emerged, powered by a 1,500 hp Merlin 145 and weighing only 8,879 pounds; top speed went up to 472 mph at 20,000 feet.

The final production result of this development process was the "H" model, powered by the Packard-Merlin V-1650-9, which delivered a maximum 2,218 hp at war emergency power (a 35 percent increase over the Packard-Merlin in the P-51D). With a 50-gallon fuselage tank that provided a total internal fuel capacity of 255 gallons, the maximum range on internal fuel was 1,000 miles, which could be extended to 1,500 miles with two 75-gallon drop tanks. With 6 .50 calibre machine guns and full provision for underwing stores, the maximum overload weight of the "lightweight" was 10,500 pounds, scarcely less than the "D." However, the airplane had a top speed of 487 mph at 25,000 feet, best of the entire series. Coupled with increased range, increased altitude capability, and better maneuverability, it was the airplane North American had set out to achieve.

The first P-51H flew on January 3, 1945, and by V-J Day that August, 330 had been produced at the North American plant in Los Angeles, with plans for increased production at the Dallas plant, where the airplane would have been known as the P-51M. Three fighter groups had completed conversion to the new Mustang, and had the invasion of Japan proceeded that fall, the type would have seen extensive combat, replacing the P-51D as the USAAF air superiority fighter in the Pacific. As it was, production ceased in late 1945, with only 550 rolling off the line.

In the late 1940s and early 1950s, the P-51H provided the former WW2 pilots who formed the Air National Guard with a weekend diversion that could truly take a man's thoughts off his weekday concerns. The last Mustang equipped several units of the ANG through the early/mid 1950s, when they were progressively replaced by the F-80 and F-84. When they were taken off operations, there were no secondary air forces for them to serve with as was the case with the P-51D, and they were rapidly turned into scrap. Today, only two are known to be in flyable condition.

Classic Airframes' F-51H comes on two trees of light-grey plastic, with petitely-engraved panel lines. A bag of resin pieces provides the parts for the cockpit, main gear well, and the drop tank pylons. There are two vacuformed canopies, which can be cut open or left closed. The Micro-Scale decal sheet provides markings for the prototype P-51H, an airplane sent to England in 1945 for evaluation, an aircraft of the 56th Fighter Group at Selfridge Field in 1947, and an aircraft of the Wisconsin Air National Guard flown by Captain Paul Poberezny (later famous in aeronautical circles as the founder and long-time President of the Experimental Airplane Association).

As with any limited-run kit, the first thing to do is clean off the flash and cut the parts away from the large sprues. I always use a razor saw for this, to keep from breaking the parts, which is easy to do.

My first step was to build the wing, so it could be set aside while I went on to other things. I assembled the main gear doors closed at the outset. On the Mustang in all versions, the gear doors are designed to stay up, out of the way of the air intake for the radiator, except when the gear is being retracted or extended, unless the hydraulic system is opened upon engine shut-down, in which case both the gear doors and the flaps will be lowered. The kit does not have separate flaps and I was not interested in cutting them away and scratchbuilding what was necessary, especially because I have never yet seen a photograph of an "H" model Mustang with these down.

I then went on to paint the resin cockpit, first interior green, then black for various bits. The kit provides a resin instrument panel for the P-51D. I know the H model panel is different, but I did not have further research to correct it. Besides, once it is under the coaming, if the modeler is going to keep that good-looking canopy closed, most of the Accuracy Police aren't going to be able to see that much anyway. I "Futured" the canopy and set it aside to dry while I went on to assemble the cockpit, and fit it to the fuselage.

With test-fitting and a bit of sanding things down, the cockpit fit inside the fuselage, and I proceeded to assemble that. Then came the wing and horizontal stabilizers. Once everything had set up, it was a case of slathering on the Bondo over most all the joints - de rigeur with a limited-run kit - and set it aside for the putty to dry thoroughly. Most of the fit of parts was as good as one can expect from a kit of this type.

Next came sanding down all the putty, and re-scribing panel lines where necessary. Since the surface detail on this model is very petite, this was very easy. I then fitted the canopy in place, glued it down and puttied around the join line. when that was dry, I sanded it out, being careful not to make too many sandpaper nicks in the canopy; fortunately, with a vacuformed canopy, such nicks as will occur can be sanded out with fine grit, and then the canopy can be repainted with Future - when it dries the nicks are gone and that big bubble is clear.

I use SnJ metal paint exclusively as the basis of my natural metal finishes. I put down a good coat of SnJ Aluminum. Once it is dry to the touch, one could (if they were uninformed) put high-tack masking tape over the paint with no difficulty - something which cannot be done with any other metal paint. However, I always use low-tack drafting tape, which never pulls up the paint beneath it. I masked off various areas of the wing and fuselage structure, and shot various Model Master Metallizer colors for different panel areas, sealing each with Metalizer Sealer. 

Once the tape came off, I then used some of the SnJ aluminum powder on other panel areas. The breaks up the monochromatic look that is often seen on models finished in a natural metal look. As I said, the secret to doing this the easy way is to use the SnJ paint as the base coat, so one does not have any difficulty with the Model Master Metalizer, which will come up if it is looked at wrong! 

Since the markings for this particular airplane were tips on flying surfaces and a black spinner and anti-glare panel, I had decided I would do all of that with decals. This is a simple process, which results in nice sharp demarcation lines and no silver overspray getting past the masking tape - an ever-present problem if one has painted these areas and then masked them off to start the NMF process.

The Classic Airframes kit decals are now done by MicroScale instead of Propagteam, which makes for a much easier decaling session. I used the markings for the Wisconsin National guard F-51H flown by Captain Paul Poberezny in 1951, and had no difficulty with any, using MicroSol to get everything to melt down nicely.

I used Aeroproducts prop blades from the Tamiya Korean Mustang kit. These may be slightly smaller than the prop for the H model - I am not sure on that - but they look much better than the overly-thick blades supplied by the kit. Once everything was assembled, I removed the Scotch tape from the canopy and...voila! The last Mustang is a winner in my book.

Any modeler who has built a couple of limited run models successfully will have no problem with this kit. It is among the best-engineered of Classic Airframes' kits, and to my mind stands head and shoulders above the HiPM kit, which I think is misshapen in too many places with a wing that is too narrow in chord.

Article, Model and Images Copyright © 1999 by Tom Cleaver
Page Created 10 October, 1999
Last updated 26 July, 2007

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