7 ms·
That said, we both know the shape of the SR-71, and the Compressor Inlet Temperature limit. The shape determines the smallest Mach angle that the entire plane f
by chipsa 3y ago
That said, we both know the shape of the SR-71, and the Compressor Inlet Temperature limit. The shape determines the smallest Mach angle that the entire plane fits inside, which gives a value for the maximum speed. The CIT limit gives a value for the maximum speed, which is roughly the same as the Mach angle value, at approximately Mach 3.3. To go faster, the plane would have to be skinnier, or the wing tips would poke beyond the Mach cone, and the entire tip would generate it's own set of shockwaves, which would most likely result in a sharp increase in temperature for the part outside the cone (which can be read as: the wing tips melt off).
- 542458 3y agoThis might be a dumb question, but isn’t that the maximum sustained speed for the plane, and higher speeds would be possible for short bursts? (as in, before the wing tips get hot enough to melt off)
- jabl 3y agoYes, that is correct, though I guess an issue would be that the drag would increase sharply if parts of the plane is sticking out of the shockwave, necessating even more thrust.
- hinkley 3y agoMy understanding of bomber height was 1) fighters and ground cannons cannot attack them directly, and 2) SAM missiles have to climb to meet them while matching velocity, and the bomber can shed altitude to increase ground velocity and outpace the missile long enough that it runs out of fuel. That puts a big gap between top cruising speed and top speed.
- VBprogrammer 3y agoIt's just nuts to think about people on Concorde sipping champagne at Mach 2.04. I wonder if that's something which will be possible again in my lifetime.
- sneak 3y agoIt's likely there will be Starship-based passenger transport from point to point on Earth within 10-15 years. The biggest hurdle will be getting countries to allow an ICBM filled with humans to approach their mainland.
- dumpsterlid 3y ago[dead]
- JustLurking2022 3y agoHighly doubt. The Concorde's problem was economics not science and a rocket based solution is even less economical - even a reusable one.
- thereisnospork 3y agoFor normal people sure, but for VIPs and especially military it will happen. Imagine being able to drop Seal Team Six into Taipei, the Red Square, or literally any other piece of earth with a ~50ft clearing on ~30 minutes notice? That's a capability which is very hard to put a price on.
- vkou 3y agoI'd like to not imagine a boots-on-the-ground shooting war, where you are launching a craft that is indistinguishable from an ICBM at a nuclear power's capital. I'd like anyone at the DOD who is imagining it to either be fired or shot, before they drag the rest of us into their geno-suicidal fantasies.
- deleted 3y ago[deleted]
- ianburrell 3y agoStarship is worse than an ICBM. ICBM carries a handful of MIRV warheads. Starship potentially carries hundreds of warheads. It is a single rocket first strike. Nobody would put that many warheads on one rocket, but the target needs to act like it could.
- xattt 3y ago> Compressor Inlet Temperature limit How do we know this is also not part of an official/unofficial limit?
- jabl 3y agoI guess the point is you can make an estimate of the CIT based on the geometry of the plane, and the speed and altitude it's traveling at. And similarly the CIT limit can be estimated from published data about the engine plus knowledge of the limits of the materials used when it was designed.
- chipsa 3y agoThis is actually an engine limitation. It's to keep the turbine blades from melting. Unfortunately, you can't measure the turbine inlet temperature very well, because of the whole melting thing. So they determine what the limit should be, and then back calculate it to somewhere they actually can measure it (which is the front of the compressor). So, you could exceed the CIT limit, but you would run the chance of damaging the engines. The MiG-25 has famously destroyed it's engines by running to fast.