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To the frontier of space: X-15 and mother ship

Walker and others would take the X-15 to the edge of space several times, but his altitude record for manned winged aircraft would stand for more than 40 years.
By Jeff Thomsen and Mark Hembree, NASA photos
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In the March 2010 FineScale Modeler, Jeff Thomsen undertakes a massively ambitious project, converting Monogram’s classic 1/72 scale B-52 and an MPM X-15A-2 to model the record-setting flight of Joseph A. Walker.
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Joe Walker in 1961: The second test pilot to fly the X-15, he set an altitude record for winged flight that stood for more than 40 years. Walker died in 1966 when his F-104 collided with an XB-70 during an inflight photo session. In 2005, NASA awarded him his astronaut wings in recognition of his X-15 flights to space.
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Describing how he modified MPM’s X-15 to model Walker’s August 1963 ride, Jeff writes, “Walker’s record flight was made in the third and final X-15 built (66672). By this time, the detachable lower ventral fin was no longer being used except on the reconfigured X-15A-2 (66671).” The white areas underneath represent frost from the X-15’s super-cold fuel of anhydrous ammonia and liquid oxygen.
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Jeff writes, “On this flight, an ultraviolet exhaust plume experiment was flown in a removable tail-cone box behind the upper speed brakes.” Notice, too, the color of the X-15’s skin; Inconel X, a highly heat-resistant chrome-nickel alloy, has a distinctive gunmetal hue – a fine point of modeling the rocket plane.
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The High and Mighty One (aka “Balls Three”) takes to the air with an X-15 under its wing. Note the wrinkly fuselage skin and the pylon holding the X-15, both features Jeff went out of his way to model. The pylon mount precluded use of the NB-52’s flaps, making takeoffs and landings adventurous for its pilots.
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The High and Mighty One in its original scheme in 1960. It was the third and last B-52A built and was redesignated an NB-52A when it was handed over to NASA for the X-15 program. It served for 93 of the X-15’s 199 flights.
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An observation dome was installed on the mother ship to provide the launch operator with this view of the X-15.
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North American’s 3-view drawing of the X-15.
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The X-15 was released from 45,000 feet – about 8.5 miles high …
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… and rocketed to a height of 50 miles in less than 2 minutes. According to a popular anecdote, Joe Walker was so shocked by the acceleration after engine ignition that he screamed, “Oh my God!” to which a flight controller replied, “Yes? You called?”
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The X-15, its fuel expended, glided to earth in an unpowered descent. With skids as its main landing gear, the rocket plane would land on a dry lakebed at about 200 mph.
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“Mom” checks in: Mother ship The High and Mighty One flies over a landed X-15 in 1961.
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November 4, 1960, four days before Kennedy was elected president: NASA prepares to make one of its four unsuccessful attempts to launch two X-15s in one day. The NB-52B in the foreground is “Balls Eight,” which served as a test bed and mother ship well past the end of the X-15 program in 1969 and finally retired in December 2004.
Of all the aircraft ever flown by test pilot Joseph A. “Joe” Walker – P-38 Lightnings in World War II, “X” planes throughout the 1950s, as well as early versions of the Century Series fighters and the B-47 Stratojet – he never soared any higher than on August 22, 1963, when he piloted a North American Aviation X-15 to an altitude of 354,200 feet (67 miles, or 107.8 kilometers), well past the 50-mile/100-kilometer-high edge of outer space (as defined by the U.S. Air Force and the Fédération Aéronautique Internationale, respectively).

Walker and others would take the X-15 to the edge of space several times, but his altitude record for manned winged aircraft would stand for more than 40 years until Scaled Composites’ SpaceShipOne took the Ansari X Prize in 2004.

North American’s rocket-powered research airplane, designed to explore extremes of altitude and speed, made its first flight in 1959. With its stubby wings, limited fuel capacity, and the high rate of fuel consumption necessary to reach hypersonic speeds, the X-15 had to be carried aloft by a mother ship to launch. Originally, program managers envisioned dropping the rocket plane from the gigantic B-36 Peacemaker’s cavernous bomb bay. But when the more altitude-capable B-52 came along, two of them were chosen as X-15 mother ships.

The first X-15 mother ship was a B-52A (tail No. 20003, also known as “Balls Three,” the third Stratofortress ever built); the second was a B model (No. 20008, or “Balls Eight”).  The chief external difference between the two mother ships was at the aft end; 20003 was stripped of its gun turret and the opening faired over, while a larger section of 20008’s tail was cut off immediately behind the gunner’s canopy.

The X-15 wouldn’t fit in a B-52 bomb bay, so it was mounted on the starboard wing between the fuselage and right inboard engine pod. A wedge of inboard flap was removed to make way for the X-15’s vertical tail fin, and the inboard flaps were bolted in the up position. Thus, all flights were accomplished without the benefit of flaps – making takeoffs and landings especially interesting for the pilots!

Large tanks for the X-15 fuel system were installed in the bomb bay of the NB-52s for topping off the rocket plane during flight. A launch operator’s station was installed on the flight deck behind the pilots with an observation dome that allowed him to view the X-15 on its pylon, and several camera housings were mounted on the right fuselage to film the launches. Several of these are available for viewing on the Dryden Flight Research Center’s Web site.

After launch, the X-15 blasted skyward as it accelerated to speeds between Mach 4 and Mach 7. At the apex of its flight – the edge of space, where flaps were ineffective in the thin atmosphere – the plane’s attitude was maintained by “reaction control” rocket thrusters. The X-15’s powered flight lasted two minutes at most, after which it made a powerless descent (like the present-day space shuttle), landing on its rear skids and nose-gear wheels at 200 mph just 30-40 minutes after its departure aboard the mother ship.

With 93 of the X-15’s 199 flights to its credit, The High and Mighty One was retired in 1969 and is on display at the Pima Air & Space Museum in Tucson, Ariz. The other X-15 mother ship, “Balls Eight,” soldiered on after the X-15 program, serving in numerous other experimental programs, including the Northrop and Martin lifting bodies. Having made its first flight in 1955, it was finally retired in December 2004. At that time, it was the oldest flying B-52 – yet, due to its specialized role, it had the fewest flight hours of any operational B-52 (2,443.8).

To learn how Jeff converted Monogram’s classic 1/72 scale B-52 and an MPM X-15A-2 to model the record-setting flight of Joseph A. Walker, pick up the March 2010 issue of FSM. View the March issue's complete table of contents and watch Editor Matthew Usher's video preview of the issue.

Want more online extras? Download desktop wallpaper of Erin Lantz's F-16 in digital camouflage.
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