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Comment by dboreham | Hacker News Reader

Even more impressive seeing it sweat fuel onto the apron in the afternoon sun for a few hours then engine ignition with Chevy V8 start cart, takeoff followed by low level transonic flyby.

Fairford IAT 1989.

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As I read it, not just one v8 but two, with straight pipes:

https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...

What kinda specialised monster engines is that plane running, holy hell.

The fuel doesn't ignite at "low" temperatures, one reason is because the whole airplane leaks fuel until it's at an high enough speed. At that point, maybe because of the surface temperature, or the forces it tackles at Mach 3+, the whole thing becomes airtight.

At least, that's what I remember.

Yup, at Mach 3+ the fuselage expands so significantly that gaps need to exist when it’s stationary, otherwise it’d buckle. So the gaps mean it leaks fuel when stationary.

It's not supposed to leak. It just that the sealant to bridge the gaps wasn't perfect, so it'd get some leaks through the sealant.

What’s more, at its highest speeds, the engine transitioned from conventional turbojet to mostly ramjet compression by extending/retracting a nose cone within each engine intake. Doing so moved the bow shockwave of the cone so that it reflected inside the engine intake, which had the effect of slowing the Mach 3 air down to subsonic speeds so it could be used for engine combustion. But even still, energies were so high that almost all the thrust came from afterburning - the engine combustion stages were basically just spinning as air went through them.

The whole plane is an engineering tour-de-force, especially considering it was designed with slide rules

The DEF-H module contains the Diesel Exhaust Fluid for the truck.

Not sure you are were trying to be serious or not, but the DEF-H was one of the defensive systems used to jam surface to air threats. The system had two "modules" with one in the left and one in the right chine.

Weren’t those big blocks on the starter cart Buicks?

They were initially Buicks, then Chevy later on [1]

[1] https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...

That was a great read, thank you. TIL about TEB, and how at one point they were investigating coal slurry as a fuel? (Although tbh that sounds like someone having fun on Wikipedia).

You can hear the starter cart in some of the YouTube videos, like this one: https://www.youtube.com/watch?v=nFO--wzFfUs - it really gets going around the two minute mark.

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