2004 csxt successful flight sonic boom analysis
2004 CSXT GoFast Space Shot Sonic Booms
SpaceShot 2004 had a number of firsts. Sonic Booms from the nose cone/payload section and the booster section were expected, but since they were so far away, we didn’t actually expect to hear them. Turns out we could hear them. And, they turned out to be important.
There was a person at the launch who was recording the sounds of the launch. It was Jeremy Cooper who had high quality recording equipment. He actually had a mannequin head mounted on a tripod with microphones in each ear recording sounds. There was also another person doing downrange surveillance 10 miles from the launch site who also recorded sounds of the launch.
Just after L+7 minutes (launch time plus 7 minutes), Jerry Larson called out on the PA for the assembled launch crew to be quiet and listen for any possible sonic booms. Just before L+8 minutes:
Jerry Larson (over PA system): Somebody's got an open mic. Everybody with a microphone, check their speaker. We've got an open mic clicking here.
rumble of booster re-entry boom
Jerry Larson (over PA system): Just heard a boom.
rumble of nose/payload re-entry boom
Jerry Larson (over PA system): Two booms.
sounds of people talking on the flight line
Some of the gathered people thought the sonic booms were a bad sign, but actually they were a good sign. And a sign that we didn’t realize was important for another 2 months. After all of the hoopla from getting SpaceShot 2004 into space and things died down, Jerry Larson decided to go back and review the sonic booms for more information. And what he found was amazing. Not only did they confirm the GoFast Rocket made it to space, it confirmed parachute attachment and the possible landing area for the GoFast rocket booster section.
In Jerry Larson’s analysis done on the audio of the sonic booms, he discovered multiple things. The quality of the recording was good enough to determine an N-shaped pattern disclosing the leading and trailing edge booms. Not only that, but it could be determined which one was the nose cone/payload section and which was the booster section. The length of time between the booms indicated the length of the object. Also, the sonic boom from the booster indicated its parachute was deployed.
Further analysis of the flight data from the avionics section of the rocket, weather and balloon data from the day’s flight, sonic boom data and simulation of the re-entry, allowed Jerry to create a realistic search area for the booster section. This missing variable for booster landing area was knowing exactly when the booster section parachute failed and parachute effectiveness. That created a search area that was 1 mile either side of a line from the "ballistic entry point" (zero parachute effectiveness) across a rugged mountain range to the point of optimal parachute effectiveness, which was near the location nose cone/payload section landing point. As it turns out Jerry’s analysis was excellent, but the actual landing point of the booster section was discovered by the BLM doing a wild horse survey from a helicopter.
Jerry Email to Ky:
From: Larson, Jerry
Sent: Sunday, September 19, 2004 6:53 PM
To: Ky Michaelson XXXX@XXXX.com
Subject: GoFast Sonic Boom Foot Print
Ky, check it out. I’ve continued working on the sonic boom prediction stuff with the top sonic boom expert in the country. This is the latest prediction of what the GoFast rocket sonic boom foot print looked like for the booster. What’s amazing about this is how accurate it predicts the time we heard the sonic booms, all based on our reconstructed trajectory simulation of the booster re-entry. What else is amazing is how far these sonic booms from reentering space objects can be heard. The GoFast sonic booms could easily be heard 60-80 miles from the focus point. The last few weeks I’ve been working on tying this software with our trajectory simulation to more accurately predicted where the booster reentered from. We have two recordings of the sonic booms, one at the launch site and the second was 10 miles away at the North train track spot. Since we know the locations and the timing of the booms at each spot, I believe I can back derive the location the booster was reentering from. If you look closely at the graph towards the focus or bullseye, there is a black line, this is the booster’s trajectory ground track on its way down from 200,000 to 106,000 feet or Mach 3.6 to Mach 1 where these waves were generated the we eventually heard on the ground after they traveled about 5 minutes to get there.
It turns out had we known this would have happened from the separated objects coming back in from space we could have known the vehicle reached space simply by the timing of the two sonic booms.
What’s really neat about this subject is the fact that it’s completely unknown in the amateur/hobby rocket community, simply because we were the first to hear a sonic boom from an object coming in from space. ….
Talk with you soon.
Jerry
2004 csxt successful flight sonic boom analysis
What is a Sonic Boom
The best photographic evidence of a sonic boom in photo to the right. It's a photo taken from a hang glider shooting pictures of the world land speed record. The dark spot in the center is the car with a huge dust trail behind it and you can see the shock wave of the sonic boom on either side of the car. Photo from the back room at Bruno's.
Land Speed Record info from Google:
The current absolute land speed record is held by Thrust SSC, driven by Andy Green, who reached 763.035 mph (1227.985 km/h) in the Black Rock Desert, Nevada, on October 15, 1997, becoming the first land vehicle to officially break the sound barrier (Mach 1.020). This jet-powered car uses twin Rolls-Royce engines, and its record stands as the fastest speed ever achieved on land, verified by the FIA.
From Google:
What is a sonic boom caused by?
Sonic boom is an impulsive noise similar to thunder. It is caused by an object moving faster than sound -- about 750 miles per hour at sea level. An aircraft traveling through the atmosphere continuously produces air-pressure waves similar to the water waves caused by a ship's bow.
How do I know if I heard a sonic boom?
Yes, it's very likely you heard a sonic boom, as they're common from military jets and SpaceX re-entries, often reported as loud booms or explosions that shake buildings, especially in areas like Southern California or the UK where military activity is high. These booms happen when aircraft travel faster than the speed of sound, creating shockwaves that people on the ground hear as a loud, sudden sound.
Youtube video explaining sonic booms:
