posted on Jul, 5 2007 @ 01:39 PM
In 1962, the first A-12 flew unpainted. Eventually, as the test program moved into performance envelope expansion, there was a need to paint the
leading edges black to better radiate heat on the hottest parts of the aircraft. The partial-black paint scheme was introduced in 1963.The YF-12A
initially shared this paint scheme.
In 1964, the A-12 fleet was painted overall black, along with the YF-12A and SR-71. As mentioned earlier, this provided better radiative heat
characteristics. The only exeption was the TA-12 trainer. It was powered by J75 engines and never flew in the Mach 3 cruise regime, so it didn't
experience the same heating profiles as the other Blackbirds. It retained its black and silver appearance.
For some reason, the first M-21 (Article 134) also remained black and silver, while its stablemate (Article 135) was painted overall black.