Bell X-5 by Revell

1/40 scale
Kit No. 8619
Cost: $15.00
Decals: One version – U.S. Air Force test aircraft
Comments: Engraved panel lines; pilot figure; movable swept wings; optional position canopy; includes complete jet engine; 1982 “History Makers” re-issue of Revell’s original 1960 kit

History

The Bell X-5 was an experimental jet aircraft flown during the early 1950’s by the U.S. Air Force and the National Advisory Committee for Aeronautics (precursor to NASA) with the goal of probing the flight envelope of a jet aircraft with a variable sweep wing.  As the first such aircraft ever built to actually fly, the X-5 represents a milestone in aviation history. Its design was so strongly influenced by the Messerschmitt P.1101, a jet-powered aircraft under construction in Nazi Germany when World War II ended, that to some it was considered the “Americanized” P.1101.

An Impressive Find
The story goes that the P.1101 was discovered by American troops who overran Messerschmitt’s experimental Oberrammgau facility in Bavaria in April 1945, and was quickly whisked back to the United States for study and evaluation, ultimately morphing into the Bell X-5.  That is mostly true, but the P.1101’s journey into the hands of Bell Aircraft wasn’t quite so fast. Both the American and Russian forces who conquered Germany had military intelligence officers in tow, who quickly identified and carted away anything that might be of later value.  U.S. Army Intelligence officers were indeed curious about the P.1101, and hunted down and interrogated Woldemar Voigt, the design genius of Messerschmitt AG who took it from the drawing board and almost to fruition by war’s end.  Voigt also conceived a startling array of what Adolf Hitler called “wonder weapons,” of which only a precious few entered production.

Behind the Wizard’s Curtain
Voigt was candid with the Americans, sharing a litany of the P.1101’s design faults, not the least of which was a highly complex landing gear requiring a motor that could retract the main gear struts rearward and upward to fold into the fuselage, above the hot metal of the jet exhaust pipe.  There were other engineering challenges: the nose gear had to pivot 90 degrees as it retracted into a well directly beneath the jet intake, and fuel was carried in three tanks along the spine aft of the cockpit and above the engine and the area reserved for the main landing gear — in a limited area that had to be shared with the wing spars.  Finally, the wings, while they were of variable sweep, could not be adjusted in flight.

Had the P.1101 flown, it would likely have fallen short of performance specifications, which called for it to attain a service ceiling of 46,000 feet – easily 10,000 feet higher than the maximum altitude reached by American B-17 and B-24 heavy bombers.  Voigt convinced Uncle Sam’s intelligence officers that the P.1101 had defied the efforts of Messerschmitt’s best engineers to mold it into a workable fighter design.

American interest in the type virtually ended on the spot, and the unfinished prototype was pulled out of Messerschmitt’s workshop and placed outdoors on static display as a curiosity — on the grass next to a Messerschmitt Me 262 bereft of its engines.  There it sat until it was discovered by Robert Woods, a civilian member of the Army’s intelligence and evaluation team, but also chief designer of the Bell Aircraft Corporation of Buffalo, New York. Upon Woods’ request, the Army agreed to ship the P.1101 to the United States in the Fall of 1946.  But it did not go directly to Buffalo — it spent another two years at Wright-Patterson Air Force Base in Dayton, Ohio for study before being shipped to Bell Aircraft.

A New Fighter?
Ultimately the dilapidated airframe was refurbished to become a non-flying full scale mock-up at Bell Aircraft for two identical experimental aircraft that would become known as the X-5.  While the X-5 is known to the world as a research aircraft, Robert Woods had the ear of company president Larry Bell, and sold him on the idea that the design could be marketed to the U.S. Air Force as a jet fighter, despite the data Voigt had shared with U.S Army intelligence on the P.1101’s limitations.  For this reason, the decision to build the X-5 at all, let alone with the goal of selling it to the Air Force, was so controversial within Bell Aircraft that it caused a rift within the company’s engineering staff.

Dissension and Departures at Bell
At Larry Bell’s direction, Chief Engineer Robert Stanley put a crack team to work on the project, launching an intensive study of the P.1101 airframe.  After a thorough review, Stanley and his team reported to Larry Bell, Woods and others in a management meeting that the P.1101 was inferior to front-line American jet fighters then in service, including the North American F-86 Sabre, itself based on German aerospace research conducted during the war.  Woods was outraged.  He rejected Stanley’s report and continued to champion the virtues of the P.1101, finally convincing Bell to build what would become the X-5 and offer it up as a contender for an American/NATO low-cost tactical fighter contract.

This view shows how completely the Allison J35 turbojet dominated the lower half of the fuselage interior. Note the main landing gear in their retracted position, folded over the engine.

Feelings ran so high about the P.1101’s unsuitability that in response, Stanley and a number of his engineers resigned from Bell Aircraft. Woods took over Stanley’s job as chief engineer and the project proceeded, leading to the first flight of the X-5 on June 20, 1951.  But Stanley and his team were vindicated when the X-5’s flight test program later proved that both their calculations and their evaluation had been right.  With its Alison J35 turbojet of 4,890 lbs. thrust, the X-5 was somewhat underpowered (in part because its most radical feature, the wing sweep mechanism, added 340 lbs. of weight) and it lacked the speed, range, endurance, and weapons carrying capability required by the U.S. Air Force.

Legacy of Swept Wing Research
Despite these shortcomings, the Bell X-5 would be enshrined in history as a cutting edge test bed for variable sweep technology, with wings that could be moved in flight from 20 degrees, to 40, to a full sweep of 60 degrees within 20 seconds.  At full sweep, the X-5 had a maximum speed of 650 mph.  Altering the wing angle changed the center of gravity, which could make the plane difficult to control.  To compensate for this, the wings were mounted, hinges and all, along rails that traversed a considerable length of the fuselage — this allowed the entire wing structure to move along the fuselage as the pilot adjusted their angle, minimizing the shift in the center of gravity. The pilot could adapt the sweep as the ocassion demanded, whether it was takeoff, landing or cruise, and supply more or less drag as needed.

The X-5 flight tests were far more rigorous than those for the Convair XF-92 and the Douglas X-3, as X-5 flight data furthered research into vertical tail loads in maneuvers, the effects on trim from shifting the wings, and the effects of dynamic pressure on buffeting.  The X-5 program helped collect data on varying wing sweeps at subsonic and transonic speeds, technology that would later influence the development of Cold War-era combat aircraft including the Grumman F-14 Tomcat, General Dynamics F-111 Aardvark and the Rockwell B-1 Bomber. The British Panavia Tornado and the Soviet MiG-23/27 would also make use of the “swing-wing” approach.

Vicious in a Spin
The Bell X-5 was based on Messerschmitt’s P.1101, but even more complex. In flight testing, it had a vicious tendency to spin, and contributed much to the study of design features that produce this reaction.  NACA test pilot Scott Crossfield, one of the X-5 test pilots, said bluntly, “It was a terrible airplane in a spin.  It took a long time to get that airplane out of a spin.”  During spin tests on October 13, 1953, the second of two X-5’s crashed, killing its test pilot, USAF Major Raymond Popson.  The X-5 was retired after its final flight on October 25, 1955. Bell proposed to re-engine it with more powerful Westinghouse J45 or Wright J65 turbojets to increase its performance, along with rocket boosters, but none of these plans were ever realized.

In 1958, the lone surviving X-5 was delivered to Wright-Patterson AFB in Dayton, Ohio, where it remains on display to this day.

Construction
Assembling the X-5 is simple, but it can be rather fiddly due to the moving wings, and the various parts for the landing gear doors, which are meant to be able to open and close — a sound concept, but in practice they flap about rather a lot while the assembly is underway.  Construction begins with the jet engine, rather than the cockpit. The large engine is a single, four-piece affair with a modicum of raised detail.  Next are the wing glove vanes, and a simple, spartan tub into which the pilot is seated.  The instructions call for placing a decal for the instrument panel, but that particular decal is nowhere to be seen on the decal sheet.  I scrounged an instrument panel from my spares box and superglued it in.  I painted all cockpit interior surfaces Testors Flat Gray No. 1163 (enamel).

Next come the main landing gear, the wings with their separately mounted ailerons, and the fitting (not cementing) of each of the glove vanes through the rail slot in the fuselage and into a part inside the fuselage that acts as a governor along the rail slot, allowing the wings to move without falling free of the fuselage.  However, the glove vanes must fit against the rounded portion of the leading edge of the wing to stay securely in place, so there is no point in attempting this step until you are ready to mount the wings, and very quickly thereafter cement the fuselage together.  Various parts cemented to the internal surface of the fuselage to secure the gear doors must be in place beforehand.  At this stage, it can be a bit confusing because some of the parts are frankly misnumbered by the instructions, but careful surveying of the remaining parts on the sprue will get you on the right track, and it helps that the kit has relatively few parts. The kit is designed to have retractable landing gear, but it is easier to simply cement the doors into place and be done with it once all painting is completed.  Your choice will depend on whether you want the kit for static display, or some other purpose. In the end, I cemented all landing gear doors into place.

This kit definitely needs a fair amount of nose weight or it will rest on its tail.  I superglued a number of ball bearings (5) into the forward end of the cockpit floor, and more (about 8) on the interior upper surface of the nose intake, where they would not be seen.  For good measure, I painted the BBs the same color as the surrounding area – Flat Gray in the cockpit, Flat Black in the case of the intake.  Since this is a 1950’s era kit and fairly simple, there is no attempt to provide intake trunking, and you can look directly into the intake of the finished kit and see the cockpit tub and the upper portion of the nose landing gear.  To remedy this, I superglued an oval-shaped section of plasticard, cut and sanded to fit into the intake, to the front of the cockpit tub, and, after carefully masking around the lip of the intake, airbrushed the plasticard part (along with the interior walls of the intake) Flat Black.  Once the fuselage halves were cemented together, I set to work with Mr. Surfacer 500 and Tamiya putty on the sinkholes, mostly along the spine of the aircraft.

Painting
The Bell X-5 is painted in an overall scheme of Tamiya Gloss White (X-2) over a coat of Vallejo acrylic gray primer.  Once the paint was dry, I went over the panel lines with a 0.7mm mechanical pencil, erasing and brushing away any excess graphite, then airbrushed on a coat of Future to seal in this little bit of detailing work and prep the kit for decals simultaneously.

Decals
The decals were kit decals provided by Revell with no additional information as to their origin. Given that they have been sitting around since 1982, they were in superb condition (although I immediately sealed them in a Zip Lock baggie when I purchased this kit in 2007).  Their quality is absolutely excellent; they have great color, are perfectly in register, possess a semi-gloss quality and held up superbly well to decal solvent, nestling into not only the kit’s panel lines but also the individual recessed rivet surface detail. These are not the typical markings found in a Monogram or Revell kit. I wish all decals looked this good and reacted this well!

Conclusion
In terms of exterior surface detail, Revell’s Bell X-5 with its engraved panel lines and flush riveting can compete with any modern day aircraft kit — all the more amazing given that it was first released in 1960.  It speaks to Revell’s perception of the X-5 at the time, given the cost of producing what was then an unusually detailed mold in some respects.  But the quality quickly falls down with the spartan cockpit, the lack of any attempt to block off the interior view of the jet intake, and the failure to depict any detail within the dive brake door and nose wheel well interiors.  These things can re remedied with scratchbuilding and patience – so the X-5 still gets high marks for providing modelers with excellent raw material, surprising for this vintage.  Highly recommended.

References

  • Messerschmitt P.1101 by David Myhra (X-Planes of the Thrid Reich Series); Copyright 1999 by Schiffer Publishing Ltd., Atglen, PA
  • www.militaryfactory.com
  • NASA Armstrong Fact Sheet: X-5 Research Aircraft – www.nasa.gov

 

 

 

 

 

 

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