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Mach 3 Bombers and the State of the Art

The RS-70 is a military endeavor intended to produce a bomber capable of Mach 3 speed.  Perhaps the concept was overambitious, considering how much that was new had to be learned and mastered. The project, in any event, has not met its timetable. The prototype has yet to fly. No doubt some of the delay is attributable to a loss of confidence by the Department of Defense in the military concept itself. Nevertheless, it is also true that delay has again and again been caused by the recurring discovery that a design requirement had outreached what was known and trusted. In other words, the state of the art, which sets the limits on what can be attempted in confidence resting on experience, had to be pushed forward through more experimentation and invention before progress could be resumed.

Still, this experience is all to the good.  Much that has been learned from the RS-70 can certainly be utilized in the design of a commercial supersonic plane. Once the RS-70 flies, and quite apart from whatever judgment may be reached as to its military usefulness, the great speed of its flight will fix dramatically in the public mind the potential thereby opened to air commerce.  Nevertheless, the experience with the RS-70 should also remind us that the transport project is not likely to be easier or less costly. The supersonic transport may well represent, in my judgement, the industry's most difficult penetration into the technological and economic unknowns.

In the piston-engine cycle, each new design benefitted substantially from the preceding one.  The DC-6 followed the DC-4, and the DC-6 was followed by the DC-6B and the DC-7, the lot finally constituting a family of airplanes. In the jet cycle, the civilian transport borrowed from the experience gained in the design, development and operation of thousands of military aircraft. Many of the problems that otherwise would have plagued the Boeing 707 were met and mastered during the long military development cycle that ran from the B-47 through the B-52 to the KC-135.

No such backlog of military operational experience can be drawn upon by the designer, yet to be chosen, of the supersonic transport.  What the RS-70 has to teach him will be confined to pretty much to what has been learned on the drawing boards, the factory floor, and in due course, from flying operations that are certain to be limited, since only three such airplanes are being built. He still will have to buy through prodigious research what is not now known.

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