NASA Lifting Bodies

From 1963 until 1975, the National Aeronautics and Space Administration, in a joint program with the US Air Force, conducted a series of flight tests of various wingless "lifting bodies" at Edwards AFB, California (Fig. 1.14). The mission of the lifting body program was to validate the concept of flying a wingless vehicle back from space and landing it precisely like an airplane. There were six different lifting bodies - the M2-F1, the M2-F2, the M2-F3, the HL-10, the X-24A, and the X-24B (Table 1.2). Some had flat tops and rounded bottoms, some had rounded top and bottom, and some had flat bottoms and rounded tops. They ranged in shape from the "flying bathtub" to the "flying flatiron." They also tried various configurations of bubble canopies, flush canopies, and different numbers of vertical stabilizers. The "M" letter designation stood for "manned," "F" stood for "flight," "HL" stood for "horizontal landing," and "X," of course, stood for "experimental." The lifting body concept had originally been developed by modifying a missile nose-cone. This was essentially cut in half, and control surfaces in the form of winglets and vertical stabilizers were then added. The fact that any of these lifting bodies could be controlled as well as they were, and landed like an airplane, was nothing short of amazing.

Table 1.2 Comparison of lifting bodies

Vehicle

Length

Span

Empty wt. (lb)

Flights

Years

M2-F1

20 ft

14 ft 2 in.

1,000

77

1963-1966

M2-F2

22 ft 2 in.

9 ft 8 in.

4,620

16

1966-1967

M2-F3

22 ft 2 in.

9 ft 8 in.

5,071

27

1970-1972

HL-10

21 ft 2 in.

13 ft 7 in.

5,285

37

1966-1970

X-24A

24 ft 6 in.

11 ft 6 in.

6,360

28

1969-1971

X-24B

37 ft 6 in.

19 ft 7 in.

8,500

36

1973-1975

Fig. 1.14 Lifting bodies on lakebed, about 1970. From left to right are the X-24A, the M2-F3, and the HL-10 (courtesy NASA)

Fig. 1.15 M2-F2 lifting body landing with F-104 Starfighter flying chase, 1966 (courtesy NASA)

The first lifting body, designated the M2-F1, was a lightweight unpowered glider nicknamed "the flying bathtub." It was built at the Dryden Flight Research Center out of tubular steel and plywood, and completed in 1963. Using a fast Pontiac convertible, it was towed across the lakebed more than 400 times at speeds as high as 120 mph. These test-tows provided the confidence for the next step. A NASA Gooney Bird (Navy R4D, the same as the Air Force C-47 or civilian DC-3) towed the flying bathtub up to 12,000 ft and released it to glide back and land. There were 77 such aerial tow-flights. The M2-F1 proved, for very little cost, that the concept of the lifting body worked, and the green light was given to continue the research.

The M2-F2 in Fig. 1.15 was much heavier than the M2-F1. Like the Bell X-1 (and all subsequent lifting bodies), it was powered by an XLR-11 rocket engine. It was built by Northrup, and a series of drop and glide flights was conducted from beneath the same B-52 that had been used in the X-15 program. The M2-F2 had only two vertical tail fins, and was therefore prone to lateral instability. It was difficult to steer. On its 16th glide test, on May 10, 1967, pilot Bruce Peterson crashed on the dry lakebed and was severely injured. Footage of this crash was later used in the opening sequence of the mid-1970s TV series The Six Million Dollar Man. As a result of this crash, the craft was modified by adding a third vertical stabilizer between the other two, and redesignated the M2-F3 (Figs. 1.14 and 1.16).

The third tailfn greatly improved the controllability of the rebuilt M2-F3, and it went on to make 27 unpowered and powered flights from 1970 to 1972, using its rocket engine to reach a top speed of Mach 1.6 and a peak altitude of 71,500 ft. The M2-F3 was also equipped with a reaction jet control system similar to rocket thrusters.

Fig. 1.16 M2-F3 in-flight launch from B-52 mothership in 1971 (courtesy NASA)

Fig. 1.17 Research pilot Bill Dana and HL-10 on lakebed with B-52 flyby. The HL-10 was the fastest and highest of the lifting bodies, and was judged to be the best handling of the three original heavyweight lifting bodies - the M2-F2/F3, the HL-10, and the X-24A. Compare this photo with Fig. 1.1 (courtesy NASA)

Fig. 1.17 Research pilot Bill Dana and HL-10 on lakebed with B-52 flyby. The HL-10 was the fastest and highest of the lifting bodies, and was judged to be the best handling of the three original heavyweight lifting bodies - the M2-F2/F3, the HL-10, and the X-24A. Compare this photo with Fig. 1.1 (courtesy NASA)

The HL-10 (Fig. 1.17) was the highest performing of any of the lifting bodies, both in terms of altitude and speed. It was the first lifting body to fly faster than sound, in May 1969. From December 1966 until July 1970, it made 37 test flights, reaching Mach 1.86 and 90,303 ft within a 9-day period in February 1970. The HL-10 had a tall center tailfin and a flush cockpit. Its fuselage was longitudinally rounded on the bottom, and laterally curved on top.

The X-24A shown in Fig. 1.18 was a result of a waxing interest on the part of the Air Force to investigate lifting bodies. It was built by Martin Aircraft, had three tailfins and a bubble canopy, and was slightly larger than the Northrup vehicles. After 28 flights, the vehicle was returned to Martin and modified into the shape of a "flying flatiron" with a double-delta planiform, flat bottom, and curved top. In this configuration it was designated the X-24B (Fig. 1.19) and made an additional 36 flights.

The NASA lifting bodies together made a total of 221 flights over a period of 12 years, not including the 400-plus tow-flights made by M2-F1 with the help of the Pontiac convertible on Rogers Dry Lake.21,22

Empowered Wealth Bible

Empowered Wealth Bible

Get All The Support And Guidance You Need To Be A Success At Attaining Wealth. This Book Is One Of The Most Valuable Resources In The World When It Comes To Everything You Need To Know For

Get My Free Ebook


Post a comment