Salute!
Good grief. The speed at various altitudes was supposed to be whatever the government specified in the contract. If not, then maybe it had better performance a thousand feet higher or lower. Big deal. 0.10 M is not a big deal when supersonic. Few fights in combat to this day have involved 1.8 M or 2.x M.
The speed is to get to the fight or the intercept.
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I flew the non "reheat" ( have to honor the primary posters here) version Spey in the A-7D. It was called the TF-41 and licensed to Allison for U.S. production. Is.that the same motor?
Someone mentioned acceleration, but sounds more like the plane more than the motor. The TF-41 was sluggish compared to the J-79 , or most GE motors. My P&W motors could not accelerate nearly a quickly as the GE ones.
Anyway, a few knots here and there is only important making up the E-M chart, and only plane I know of that flew up at the top of that chart was the SR-71.
Gums sends...