RS Models 1/72 Northrop XP-79B, by Scott Van Aken

In 1942, John K. Northrop conceived the XP-79 as a high-speed rocket-powered flying-wing fighter aircraft.

In January 1943, a contract for three prototypes designation XP-79 was issued by the United States Army Air Forces.

To test the radical design, glider prototypes were built. One designated MX-324 was towed into the air on 5 July 1944 by a P-38 making it the first US-built rocket-powered aircraft to fly.

Originally, it was planned to use a 2,000 lbf (9 kN) thrust XCALR-2000A-1 "rotojet" rocket motor supplied by Aerojet that used monoethyl aniline and red fuming nitric acid; because of the corrosive and toxic nature of the liquids, the XP-79 was built using a welded magnesium alloy monocoque structure (to protect the pilot if the aircraft was damaged in combat) with a ⅛ in (3 mm) skin thickness at the trailing edge and a ¾ in (19 mm) thickness at the leading edge. However, the rocket motor configuration using canted rockets to drive the turbopumps was unsatisfactory and the aircraft was subsequently fitted with two Westinghouse 19-B (J30) turbojets instead. This led to changing the designation to XP-79B. After the failure of the rocket motor, further development of the first two prototypes ended.

The pilot controlled the XP-79 through a tiller bar and rudders mounted below; intakes mounted at the wingtips supplied air for the unusual bellows-boosted ailerons. Though it was to be armed with four .50 cal machine guns, initially the aircraft was to be unarmed and to down its foes by slicing through their flying surfaces with its thick wing leading edge.

The XP-79B (after delays because of bursting tires and brake problems on taxiing trials on the Muroc dry lake) was lost on its first flight 12 September 1945. While performing a slow roll 15 minutes into the flight, control was lost for unknown reasons. The nose dropped and the roll continued with the aircraft impacting in a vertical spin. Test pilot Harry Crosby attempted to bail out but was struck by the aircraft and fell to his death. Shortly thereafter, the project was cancelled.

Not much plastic in the box for this one. A single grey sprue and a clear one with the canopy rattles around in their small size box. The canopy is in two halves split down the middle, which is where it appears there was a join area on the real aircraft.

The rest of the kit is pretty standard stuff for RS Models. Very nicely engraved detail with some rather large ejector pin stubs on the inside of the wings, intake pieces and a bulkhead piece. Easy enough to remove. The cockpit will take most of your construction time as it consists of inner walls and bulkheads as well as the flight controls. There is a pad for the pilot to lay on but it looks pretty far back in the fuselage to me.

There are intake pieces that go back about a half inch and one has to insert exhaust cones prior to closing the fuselage halves. I doubt if this will be a tail sitter, thanks to the two nose and two main landing gear assemblies (building showed this not to be the case and it needs a lot of weight). If anything, one will have to be careful to make sure all four tires touch the ground. Apparently the outer nose and outer main gear doors were normally closed, and one wonders why these parts were even included at all. The inside of the gear wells and doors is shown as chromate yellow with the interior also in this shade.

Instructions are well drawn and pretty minimal as you might expect from so few parts. Markings are for three planes. One is the aircraft that actually flew. It is limited to wing insignia and a tail serial. The painting instructions state it was white, which is an interesting choice and probably based on extant black and white photos. If it were truly white, it would be the same shade as the inside of the wing insignia, but it appears a bit darker so I think it was probably pearl grey like the P-80. It is difficult to tell, but seems logical. The other two markings options are for a British version in test colors and an operational version based in Alaska with red on the leading edges of the flight surfaces. The small decal sheet is nicely printed and should work beautifully.

CONSTRUCTION

Since the kit is really quite simple, it makes sense to follow the instruction sheet on this one. I started by painting all the interior bits with US Interior Green. I know the instructions state Chromate Yellow, but that really doesn't make sense for a cockpit. The instrument panel and side panels were painted Black with the head cushions and floor cushion painted Cavalry Brown. The control 'wheel' was painted Aluminum with Black grips and the column shaft was painted Aluminum. There is a V brace that got the US Interior Green treatment as well.

There are grooves in the lower fuselage for the steering shaft, but before that is installed, the V brace needs to be glued in front of the aft one. The brace is too thick at its juncture and needs to be severely sanded down to sit low enough for the shaft to fit into its notch in the back. You also need to trim the shaft right at where it goes into the area for the canopy glass or you will not be able to fit it behind the instrument panel. It is a close fit even when doing that. I would not waste a bunch of time detailing the cockpit as not much will be seen once the fuselage halves are joined.

Before joining the upper and lower sections, the exhaust pieces need to be installed. Then the ejector towers need to be trimmed flush. Do not forget the ones on the wheel well pieces. I also added weight in the intake areas relatively close to the front as the instructions indicated they would be needed. Once the halves are joined, filler is required in some of the areas. I removed the ejector towers from the intakes and attached them. Fit is not very good. The fins were the next items glued on. These are handed by having the tabs different lengths. These tabs are a bit too deep so were sanded down prior to gluing.

Once the intake gaps were sanded, I decided to attach the nose transparency. I was extra careful in removing the sprue attachment stub and equally careful applying cement to the two halves. Once together and dry. I test fit it. It was then that I discovered that the lower part of the control yoke prevented a good fit so out came the grinder and that area was ground away. Once the canopy was in place, it was masked and I headed for the paint shop. RS correctly did not include rudders on the fins though these are shown on the markings guide.

COLORS & MARKINGS

The kit's instructions call for the aircraft to be overall white. Perhaps this is correct, but I always figured it was a grey color, such as what was on the Lockheed P-80. I certainly does not look white in photos, so I set about looking for a suitable grey. ADC grey is too dark and it was suggested that I try Vallejo Sky Grey. So after the usual primer, I sprayed on the Vallejo and followed it with a good spray of Future to gloss it up. One shade paint schemes sure help the build go along smoothly and though it darkened up with the application of the clear, it is still light enough to be different from the ADC grey. Back at the bench, I brush painted the wheel wells using Testors Zinc Chromate Yellow.

FINAL BITS

The gear legs were painted aluminum and then removed from the sprues and cleaned up. The mounting holes needed to be drilled for the front gear and enlarged for the rear, something I have come to expect from most short run kits. I also had to drill out the holes for the axles for the main gear. There are no axles for the front, just some stubs that will fit into the indentations on the front wheels. I also had to cut off the outer

gear doors and glue those in place in the closed position. The main gear doors were a perfect fit, while the nose gear doors are a bit loose. It also seems that there is a bit of gear door missing from the nose as the section that fits into the groove in the side of the intakes is not provided.

Meanwhile, the wheels were painted. I am pleased that RS provides a rim outside of the wheels as this sort of thing makes painting the tires so much easier. I do wish that ALL kit companies would provide this feature. Once the landing gear was dry, the wheels were glued in place along with the inner gear doors. Unfortunately, I discovered once the wheels were on that I did not have enough weight in it. Even filling the nose gear wells was insufficient. I recommend to you who build this that you put as much weight forward of the main gear legs as you can find s

pace for. I ended up drilling a hole for a small section of .010 bronze wire near the rear of the model to hold things up. The last part to add was the radio mast.

As things were already glossed up, putting on the few decals of the prototype was not an issue, though the decals are VERY thin so must be handled with some care to prevent damage. This was then given a coat of semi-gloss as it was just too shiny. The last step was to remove the masking from the canopy.

CONCLUSIONS

KIT #:	92111
PRICE:	$29.95 SRP
DECALS:	Three options
REVIEWER:	Scott Van Aken
NOTES:	Short run kit