United States Strategic Bombers 1945 - 2012 by Stuart Slade

Author:Stuart Slade [Slade, Stuart]
Language: eng
Format: epub
Tags: Non Fiction
Publisher: Lion Publications
Published: 2013-03-05T00:00:00+00:00

Valkyrie Ascendant

Accordingly, the Eisenhower administration announced that the downsizing of the XB-70 program would be reversed, and that the B70 Valkyrie would now be scheduled for production and service. Twelve B-70 prototypes were now called for in the development program. Work on the weapons, sensor and defensive subsystems that had been placed on hold was restarted. In fact, the performance of the B-70 against existing and future Soviet air defenses was so impressive that an RS-70 variant (RS for reconnaissance strike) was also introduced that would provide a reconnaissance defense suppression capability. It was planned that 60 RS-70s would be available by 1969 to supplement the bomber fleet.

Another issue raised during this debate was that of radar crosssection. It was claimed that the Valkyrie had a radar cross- section some 10 times greater than that of the B-52 and that this would enable the defenses it faced to gain a decisive advantage over it. Once again, this argument grossly oversimplified a complex situation. The RCS is different for each "look-angle" (i.e., direction from the threat radar). When graphed in polar coordinates, RCS appears as shown. The following illustration depicts actual data for the B-70. As can be seen, RCS varies widely from different directions, by almost four orders of magnitude for this design.

Radar Cross-Section of the B-70

Source: U.S. Air Force

Directions from which the RCS of an aircraft is very high are described as "spikes." These are typically perpendicular to the leading and trailing edges of the wing, perpendicular to the flat side of the aircraft, and directly off the nose and tail due to the inlets, nozzles, radome, and other features. For the B-70, huge spikes are evident to the sides perpendicular to the big flat sides of the nacelle. However, a B-70’s cruising speed was well in excess of Mach 3 and it few at altitudes greater than 80,000 feet; therefore, intercepting a B-70 that was already flying past a defensive installation was impossible. The primary weakness in the B-70 RCS was that there were substantial spikes just off the nose, perpendicular to the leading edges of the canards, which had fairly low sweep. These would be eliminated on operational B-70s by the use of the radar-absorbing materials being developed for the A-12 and SR-71 Blackbird aircraft. This would have reduced the nose-on signature by several orders of magnitude to the point where it was smaller than the B-52’s.

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