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Just happened to catch coverage of the approach and landing while driving into work this morning. Glad all are home safely. I'm not a space geek, but they did some pretty amazing stuff up there this time - that backflip was impressive. I hear they're going for a misty next trip.
http://www.nasa.gov/externalflash/rt...main_image.jpg
edit - they be changing pics on me.
I used to live at Edwards AFB (where it landed), and shuttle landings were always impressive to watch....they always started with a double sonic boom....*ba-BOOM-ba-BOOM!*
Glad that they made it home alright and that another re-entry like Columbia's didn't occur.
Idiot question. Why two booms?Quote:
Originally Posted by Jumper Bones
cause one is never enough...DUH!
Seriously, I'd guess that it's because the shuttle is pretty big, so the first boom is the nose and the second one is the tail.
that had to be coolQuote:
Originally Posted by Jumper Bones
I don't know, but I'll ask my dad (he's an aeronautical engineer and test pilot).Quote:
Originally Posted by bad_roo
decerleration? Hmm.
Sonic booms are real common there, lots of jets going about out there, but are rarely double booms like that.
My favorite was all the people moving into subdivisions out there, and bitching about all the jet noise and sonic booms. It was the middle of the goddam desert! That base has been there for over 60 years, it's a known! If you want a nice, quiet, semi-suburban town with access to LA, move to fucking Victorville or Bakersfield!
Yeah, the alarm went off this morning around 5:00 bringing me news about the shuttle's decent. I hit snooze, and was laying in bed went baBOOM!!! Sounded like a Battleship was just off the pier, picking a fight with LA. I then decided it was time to get up.
7PM here, and I'm barely functioning - never was able to go back to sleep after those booms at 5AM this morning. And I was too lazy to get up and check if they were home safe - glad to hear they are (which is part of what kept me awake - the wondering).
Okay, so I talked to my dad, and snow_slider was right on the mark - due to the shuttle's *relatively* large size, there are two shockwaves coming from the vehicle - hence the two booms. The only airplanes that go supersonic these days are fighters or are fighter-sized (such as SpaceshipOne), which makes the Shuttle's boom-style abnormal in this age; back in the day there were larger aircraft, like the XB-70 bomber and SR-71 Blackbird, and they were large enough to have abnormal booms as well.
and believe it or not, a 747 airliner has been supersonic - a Boeing flight test aircraft accidentally crossed the mark during a test of an autopilot malfunction reaction period. It was in a dive, and like the freight train it is picked up enough airspeed fast enough...now THERE would have been a boom...
Ask your pop this: what is so dangerous about a 747 going supersonic? I know it's not designed to go that fast, but is the danger from it being torn apart by the wind forces? Dissipation of heat? Inability to control the airplane?Quote:
Originally Posted by Jumper Bones
I think it's the super more than the sonic.Quote:
Originally Posted by pube-in-my-taco
Well, there's a lot to it - the drag from the engines at those kinds of speeds (not exactly optimal for a high-bypass turbofan), the stresses & heat dissipation needed from sustained high-mach numbers, fuel consumption, balancing, and center-of-gravity issues, and also flight controls. It's a whole pandora's box of issues, which is why the Concorde looks so outlandish by comparison to the 747. They just do different things.
The problem with airliners isn't the going straight thing, or going up - it's going back down. Like a freight train, large airplanes like that can pick up speed and momentum verrrrrry quickly while descending, and can eventually get themselves in a fix where the spoilers are inefficient at dumping speed, and the only way to recover the aircraft is to over-G (overstress) the airplane. It's not as bad as it sounds, however it is something that has to be considered; it is why commercial planes start their descents to the destination fields from so far out.
AD, you're welcome to help me out here.
One thing not a lot of people realize is that the 747 is actually a very fast airplane, because of its shape. Put the right motors on it, and it can zip right along at very high speeds, just below supersonic. The last major update to it was done in the late 80s/early 90s; an "Advanced" version with newer-technology engines is likely to be launched by Boeing by the end of the summer or early fall. Aircraft engine technology has matured at an exponential rate over the last 10 years, with SIGNIFICANT gains in thrust and fuel efficiency; it's pretty comparable to computer gains in CPU speeds & miniaturization of circuitry in the 90s. Boeing had a concept called the "sonic cruiser" that would have flown at high speeds, just below the supersonic threshold (0.90 to 0.95 mach), and when coupled with distance would have cut 2-3 hours off of legs like LA or New York to Tokyo, and probably up to an hour or more off most domestic routes. And all that with no sonic boom issues (which is what, along with high operation cost, killed the Concorde) at all, no matter where it overflew. They ended up going for the 787, ultra-efficient model instead, but they could have pulled it off easy.
Anyway the 747 thing had to do with the high mass, picking up speed quickly, and aerodynamic airframe thing more than it had to do with raw power. It happened accidentally, in a dive.