Slashdot Mirror
NASA Wants to Take the Blast Out of Sonic Booms
coondoggie writes to tell us that NASA and JAXA (the Japan Aerospace Exploration Agency) have announced a partnership to study the sonic boom. Hoping to find the key to the next generation of supersonic aircraft, the research will include a look at JAXA's "Silent Supersonic Technology Demonstration Program." "The change in air pressure associated with a sonic boom is only a few pounds per square foot -- about the same pressure change experienced riding an elevator down two or three floors. It is the rate of change, the sudden onset of the pressure change, that makes the sonic boom audible, NASA said. All aircraft generate two cones, at the nose and at the tail. They are usually of similar strength and the time interval between the two as they reach the ground is primarily dependent on the size of the aircraft and its altitude. Most people on the ground cannot distinguish between the two and they are usually heard as a single sonic boom. Sonic booms created by vehicles the size and mass of the space shuttle are very distinguishable and two distinct booms are easily heard."
Hmmph. I recommend reading Tom Wolfe's The Right Stuff, which contains much factual(and entertaining) data about test-flying in the era of the original space-race, to include much first-hand data about supersonic flying in the upper atmosphere(hint: it's much more dangerous than it sounds). Come on, Nasa & JAXA: find some folks with the right stuff and concentrate on long-term space station and moon missions. Don't piss away our taxpayer dollars exploring something that's already well-known! Who gives a fuck if China has stealth and who gives a fuck of ours is better than theirs! Should we all go to war, we'll be fucked by nukes anyway. Can't we just have a healthy space-race(V 2.0) pissing contest?
How do you make an engine where the supersonic airflow doesn't damage the compressor parts? Carefully.
I think the answer involves less airplane and more engine. Theoretically a J-58 engine by itself could operate supersonically with minimal shock waves since it is designed to reflect the shock waves into the engine in a way that they are subsonic before touching moving parts. The tricky part is adding the parts of the airplane the give lift and space for pilots to sit.
Guile was dropped from Street Fighter II sequels. There's just no more blast in his sonic boom.
Why NASA...? Why not the DOD, this sounds more suited for a stealth plane.
Disclaimer: I am not god.
We may not be created equal
But we can be treated equal.
Where is the fun in that. I kind of like hearing one of those guys step on it a little to hard over New Mexico and Texas.
Yeah, there goes my 20 million dollar plane.
I mean I never get to see them drop bombs, but at least I get to see them tag and make some booms every once and awhile.
He who said 1,000,000 monkeys on 1,000,000 typewriters would eventually type the great novel, never saw an AOL chat room
I lived in Bakersfield, CA, in the 1970's when the shuttle was being tested. It's glide path many times took it right over head, enroute to Edwards. And yes, it has two very distinct sonic booms. Loud ones, at least at that range and altitude.
I live in the Edwards Air Force Base restricted air space, so we here many sonic booms in any given week, mostly from small fighter jets. In every instance the double boom is clearly audible, unless it's a tail-less spacecraft like SpaceShipOne. Whenever we hear a single boom, it is blasting going on at the nearby CalPortland Cement Plant limestone quarry or the gold mine.
Sometimes the booms are so loud the windows shake and things rattle around. We all love it because that's why we're here. But reducing the boom signature is an important area of research, so 'normal' folks can have supersonic airliners going overhead without disturbing their chiuahua's sleep patterns. That's why the concord only flew ocean routes. It would be nice to have supersonic transport between LA and New York.
--Mike
Uh oh...
It sounds like moose and squirrel were thwarted. Unfortunately for the Russians Comrade Badenov developed capitalistic streak and did not deliver formula on to glorious Air Force
You either believe in rational thought or you don't
The last thing NASA needs is the USAF's Guile to come after them.
But Guile didn't really yell "Sonic Boom". At that sample rate it sounded more like "Phonic Poo". You'll have to wait for an article about phonic poo to repost your comment.
The state you are in while your HEAD is detached... - wait, what?
They've been working on this for a while, actually: See - http://www.nasa.gov/vision/earth/improvingflight/supersonic_jousting.html That particular project was wrapped up.. but maybe the plan to expound upon it =)
And supersonic air travel did not pay when oil was $20 a barrel, how can it ever pay at $120 ?
And there seems to be some insurmountable obstacles in softening up a sonic boom-- you've already exhausted all options by traveling faster than the air can move out of the way....there's no t much wiggle room or time left.
I remember when the SR-71 set the transcontinental speed record in the late 1970's. (They have since improved on it a little.) The boom was quite loud and clearly double, and I was impressed at how much energy was wasted by it, given that I was 30-40 km away, and that it made the same boom across the entire country. That flight was a little under a km / sec average velocity.
That's why, unless there is some real drag breakthrough, I think that rocket planes are the way to truly fast passenger travel. One ballistic impulse of 7 km / sec or so to get up above the atmosphere and on your way is 50 times the energy requirement of the SR-71 to get to maximum speed, but that would get you across the Pacific in 30 - 40 minutes and use less energy than a Mach-3 aircraft, which would take 2 or 3 hours for the same trip. Plus, except at re-entry, a rocket plane has no sonic booms.
Considering it's the aerodynamics that cause sonic booms in the first place, I would think a rounded craft would make a louder boom.
Then if you consider the drop in efficiency due to the serious amount of drag that would add, and the increase in fuel consumption, it wouldn't be viable to have a rounded craft in atmosphere.
Learn something new.
So the shuttle goes boom boom?
It goes "ba-boom". The two booms are far enough to be perceived as distinct but still close enough together to be one event.
Now if it knocks over something metallic it goes "ba-boom, CHING!"
(Thank you, thank you. I'll be here all week...)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Yes, but then the second shock wave hit and straightened things around.
http://www.rootstrikers.org/
So does the SR-71 or at least it used to. I live in the flight pattern for beale air force base and have for many years. Back in the 70's SR-71's and their T-38 chase planes and U-2's filled the air. Even being 25 miles away the SR-71 doing an engine run up would make the air rumble. Sonic Booms were part and parcel as well. Now we only get the booms of the Beale EOD and the Explosions from the gold fields mining near the base. Still the U-2's and T-38's, KC-135's and C-5A's fly by.
Just a couple days ago my son asked me if a bullet makes a sonic boom? (for the record I don't own a gun) I thought about it for a sec. and came to the conclusion that it probably doesn't or it makes a VERY small one. A bullet is traveling at faster then the speed of sound almost instantaneously. There would be no time for sound to build up in front of it, That was my thought anyway. I don't see a way to help NASA with that info but was an interesting question.
If you could reason with religious people, there would be no religious people
http://www.gulfstream.com/news/releases/2005/051108d.htm Gulfstream is working on reducing sonic booms. If the decibel level is brought low enough, it could pave the way for supersonic domestic/private flights over US soil.
There was supposed to be an earth shattering kaboom!
It's got nothing to do with military vs. civilian. Airliners depressurize occasionally. But they fly low enough that simple airmasks can suffice while the pilots do an emergency descent into the range of breathable atmosphere. You fly high enough and an airmask isn't gonna do the trick anymore.
The darkness... controls the music. The music... controls the soul.
A few pounds per square foot is a few hundredths of a pound per square inch. 14 psi + 1 lb/sq ft is 14.007 psi.
-Tom Duff