Aerospike Nozzle

The performance of the propulsion systems in this chapter are based on a conventional convergent-divergent (C-D) nozzle (Figure 4.45). At low altitudes, external

Conventional convergent-divergent

Aero-spike

Conventional convergent-divergent

Aero-spike

Aerospike Nozzle
Overexpanded

Figure 4.45. Alternate expansion nozzle configuration.

Overexpanded

Overexpanded

Figure 4.45. Alternate expansion nozzle configuration.

atmospheric pressure causes the nozzle flow to separate from the nozzle wall (under-expanded in Figure 4.45). Because the nozzle exit area is now larger than the under-expanded flow, the transonic base drag can be very large. The aero-spike nozzle (Figure 4.45), on the other hand, can accommodate higher external pressure while reducing base drag. The difference is that the C-D nozzle has one combustion chamber and throat whereas the aero-spike nozzle has a number of smaller rocket chambers around the periphery of the central spike.

To the author's knowledge, one of the first tests of an aero-spike nozzle was in the Cornell Aero Labs transonic wind tunnel in the late 1950s and early 1960s.

The Saint Louis Science Center sponsored the Russian Space Exhibition in 1992, when one of the authors (P.C.) was able to participate in some of technical sessions with the accompanying engineers. One engineer the author met was Konstantin Petrovich Feoktistov, who was the designer of Voskhod, Soyuz, Salyut, and Mir, and formerly a member of the Sergei Pavlovich Korolyov team.

Even though it is now over 40 years since the Russian Moon program, the action of Glushko's OKB to block hardware from being delivered to Korolyov is still resented. During the technical meetings there would be angry exchanges in Russian between Glushko's OKB members and Feoktistov. When the author was able to visit Moscow and Saint Petersburg on an educational exchange in 1993, he was able to visit Feoktistov at his apartment. Feoktistov had a bookcase on one wall that was filled with his design studies. One was for a multi-launch launcher designed around an aero-spike nozzle that he had tested full-scale.

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