The date is sometime in January 1945. The place, the North Sea German rocket installation known as Peenemünde. The rocket, the dreaded V-2, is about to be launched, but something is strange here. This V-2 has large swept-back wings. The countdown starts... Zehn!... Neun!... Acht!... Sieben!... Sechs!... Fünf!... Vier!... Drei!... Zwei!. Eins!. Feuer! The vertical winged A-4b, as this new creation has been christened, thunders to life and roars off the launchpad. Soon it has disappeared from view, but is tracked with long-range instruments. The winged rocket flies effortlessly through the speed of sound, coasts upward to the peak of its trajectory, and arcs over into a high-speed dive. A slight buffet arises as one of the wings begins to work itself loose. Then it suddenly rips off at Mach 4. The first supersonic rocketplane has just been born - and killed.
Ballistic missiles are structurally simpler than any winged vehicle, with the requirement to handle only longitudinal loads rather than transverse stresses as well. Toward the end of World War II, German engineers affixed wings to their V-2 with a goal of increasing its range. In the first launch attempt of the modified missile, the rocket failed for reasons having nothing to do with its newly attached wings. In the second attempt, the vehicle worked as intended, and the rocket attained gliding flight for a time before aerodynamic forces ripped one of the wings off. But the experiment proved that a ballistically launched rocket could become a winged glider, presaging the Space Shuttle by almost 40 years (Fig. 3.1).
The German experiments with winged versions of the V-2 show how difficult it can be to marry the two independent technologies of aeronautics and astronautics. For although they both involve flying machines, the similarities end abruptly at that point. Aeronautics has always immersed itself in a relatively benign atmosphere full of oxygen, lift, and propulsive potential. Rocketry, on the other hand, has always been concerned with getting above the atmosphere and into the vacuum of space. Aircraft rely on the atmosphere in many ways. Rockets shun it completely, preferring the bold independence of the impulsive dash into orbit.
The development of the spaceplane insists on the marriage of the two apparently unrelated sciences of aeronautics and astronautics, a daunting task. For although aircraft tend to take off in a horizontal attitude, space vehicles are typically lofted from their launch pads in a vertical fashion. Aircraft and rockets are therefore built to handle very different stresses and loads. Rockets are simple vertical tubes, filled
M.A. Bentley, Spaceplanes: From Airport to Spaceport, 39
doi:10.1007/978-0-387-76510-5_3, © Springer Science + Business Media, LLC 2009
with fuel and oxidizer, constructed specifically to endure longitudinal loads, whereas aircraft must support transverse loads through their wings and landing gear. These factors clearly distinguish the design of rockets from aircraft, illustrating just one of the challenges in melding these two approaches in a single vehicle.
Let us now take a look first at airplanes, then at rockets, to gain some appreciation for each of them separately, before we examine the fusion of these two technologies in the spaceplane.
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