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Reading the other day about the time an A12 pilot used his undercarriage as air brakes to slow down from full speed.

The full speed of an A12 (codename Oxcart) was Mach 3.2. The plane was later developed into the more famous SR71 Blackbird.

Apparently the Lockheed engineer in the debrief room, on being told, snapped his pencil in surprise.

The pilot said it was “very loud”. I bet it was!

in reply to Sarah Brown

Petra
Petra
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That's a bold move - but why did they need to slow down so desperately?
in reply to Petra

Sarah Brown
Sarah Brown
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@Petra they normally did it by flying a 200 mile radius circle over the southwestern US desert. It took a long time.

I guess he needed a piss or something.

@Petra
in reply to Sarah Brown

Katie Fenn
Katie Fenn
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Would you mind sharing the source? I’m reading Skunk Works by Ben Rich and would love to read more about the A-12 and SR-71.
in reply to Katie Fenn

Sarah Brown
Sarah Brown
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@Katie Fenn There's one (SR71) at Duxofrd which you can get up close and personal with. Amazing engines. Very nearly turbo ramjets.
@Katie Fenn
in reply to Sarah Brown

Katie Fenn
Katie Fenn
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Thanks for the link!

Love Duxford - here’s my own photo of their Blackbird. Hope it gets a F-117 Nighthawk and a B-2 Spirit one day…

SR-71 Blackbird at Imperial War Museum Duxford. A sleek black spy plane, optimised for flight at Mach 3 and above. It has characteristic “chines” around its outline to deflect radar, and its matte black paint radiates vast amount of heat generated from the friction of the air. It has two massive jet engines in its swept back delta wings, indicating its high power and low weight.
This entry was edited (1 year ago)
in reply to Katie Fenn

Sarah Brown
Sarah Brown
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@Katie Fenn last time I was there, one of the engines was out on display, which was cool!
@Katie Fenn
in reply to Sarah Brown

Katie Fenn
Katie Fenn
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Yep, it’s tucked under the wing, just out of shot. Amazing to think that, as big as the engines are, they’re not even generating half the total thrust at Mach 3.
in reply to Katie Fenn

Sarah Brown
Sarah Brown
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@Katie Fenn I guess that makes sense. The highest dynamic pressure on the vehicle is around Mach 1, at low altitude. They probably can't operate at full power at high speed because loads of the airflow is bypassing the turbine, pretending to be a ramjet.
@Katie Fenn
in reply to Sarah Brown

Christine Burns MBE 🏳️‍⚧️📚⧖
Christine Burns MBE 🏳️‍⚧️📚⧖
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You’d think that would carry the same risks as landing on water. With the wheels wanting to suddenly go slower than the fuselage there would be a huge rotational moment.
in reply to Christine Burns MBE 🏳️‍⚧️📚⧖

Sarah Brown
Sarah Brown
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@Christine Burns MBE 🏳️‍⚧️📚⧖ it would induce a pitch-down tendency for sure, but nowhere near as much as water. It’s still moving through the same fluid as the rest of the plane at this point: the air. All it does is lower the centre of drag (and increase it massively), but the aircraft would easily be able to counter it.

Not a massive amount of stress on the wheels too. Mach 3.2 is fast as hell, but it’s at 80,000 feet and the air pressure up there is tiny. Someone calculated that it’s like doing 330 knots at sea level. That would be deeply unpleasant and probably cause significant injuries to a human, but the plane would be just fine. It’s just utterly wrecking the aerodynamics.

@Christine Burns MBE 🏳️‍⚧️📚⧖
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