The Bell X2 Starbuster 19521956

Following the transonic and supersonic research mission of the X-1 up to about Mach 2, the X-2's goal was to investigate the region above Mach 3. The X-2 program was a joint effort between Bell Aircraft, the US Air Force, and the NACA. It was plagued with problems, and ultimately took the lives of three men. Bell built two swept-wing aircraft, each containing a Curtiss-Wright XLR-25 throttleable liquid-fueled rocket engine with two thrust chambers. One was a 5,000-lb chamber and the other, a 10,000-lb thrust chamber. The X-2 could therefore develop anywhere from 2,500 to 15,000 lb of thrust. It was fitted with an escape capsule in the form of a nose that could be jettisoned with a stabilizing parachute. The pilot would then bail out when he reached a safe altitude. A Boeing B-50A mothership would release the X-2 at around 30,000 ft, as seen in Fig. 1.11.

During a captive-carry flight to check the LOX system over Lake Ontario in 1953, there was an in-flight explosion resulting in the loss of X-2 pilot Jean L. "Skip" Ziegler, B-50 crewman Frank Wolko, and the X-2 itself, which fell into Lake Ontario and was never recovered. These were the first casualties of the problem-ridden program. But the Air Force still had one X-2 left.

USAF Captain Iven C. Kincheloe earned the title "first of the spacemen" when he flew the X-2 to 126,200 ft on September 7, 1956, a new record. Only weeks before this flight, NACA had requested use of the X-2, but the Air Force wanted to make one more flight in an attempt to reach Mach 3.

On September 27, 1956, Air Force Captain Milburn G. "Mel" Apt flew the rock-etplane to a record 2,094 mph, or Mach 3.2, at 65,500 ft. Although warned not to make any abrupt control movements above Mach 2.7, he turned sharply back

Fig. 1.11 Bell X-2 ignites rocket engine after drop from B-50 mothership, 1955 (courtesy NASA)
Table 1.1 Early American rocketplanes

Max.

Empty

speed

Max.

Rocketplane

Length

Wing span

wt. (lb)

Flights

(mph)

Mach

Bell XS-1

30 ft 11 in.

29 ft

6,784

157

957

Mach 1.4

Bell X-1A

35 ft 7 in.

28 ft

6,880

26

1,650

Mach 2.4

Bell X-1E

31 ft 10 in.

22 ft 10 in.

6,850

26

1,471

Mach 2.2

D-558-2

42 ft

25 ft

9,421

313

1,250

Mach 2.0

Bell X-2

37 ft 10 in.

32 ft 4 in.

12,375

20

2,094

Mach 3.2

71,90210-11 90,44012-13 73,05014-15 83,23516 126,20017-18

71,90210-11 90,44012-13 73,05014-15 83,23516 126,20017-18

towards Edwards while still above Mach 3 and encountered a dangerous control divergence known as inertial coupling. The vehicle tumbled out of control, and both he and the only remaining X-2 were lost. Capt. Apt did manage to jettison the crew capsule, but this impacted the desert floor before he could bail out.9

Table 1.1 summarizes the first three important American rocketplanes. The X-1B, not listed, made 27 flights and was very similar to the X-1A in both dimensions and performance. The X-1C was cancelled while still in the mockup stage. The X-1D was destroyed on its second flight after a small explosion and subsequent jettisoning from the B-50 carrier (Figs. 1.12 and 1.13).1920

Fig. 1.12 "Cowboy" Joe Walker mounts his steed, the X-1A, in 1955 (courtesy NASA)
Fig. 1.13 Bell X-1E being loaded in B-29 mothership on ramp, 1955 (courtesy NASA)

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