Red Bull Stratos: A Mission to the Edge of Space. 08th Oct
Discussion
I never said it was useless. But it certainly hasn't got the need behind it that was there 50 years ago.
However, when Kittinger was doing his jump there was a very sound engineering reason for doing it. Pressure suits needed to be tested at near space vacuum for upcoming space launches - which patently isn't the case these days. And there were limits to what could be achieved in vacuum chambers so it was deemed that high altitude testing of the suits was the best way to carry out "real world" tests.
I'll be watching the Red Bull "experiment". It's still a difficult and dangerous feat to attempt. But it's relevance to real engineering is limited and it is now more of a dangerous stunt for publicity purposes.
However, when Kittinger was doing his jump there was a very sound engineering reason for doing it. Pressure suits needed to be tested at near space vacuum for upcoming space launches - which patently isn't the case these days. And there were limits to what could be achieved in vacuum chambers so it was deemed that high altitude testing of the suits was the best way to carry out "real world" tests.
I'll be watching the Red Bull "experiment". It's still a difficult and dangerous feat to attempt. But it's relevance to real engineering is limited and it is now more of a dangerous stunt for publicity purposes.
warp9 said:
Loving that the launch is in Roswell, New Mexico.
Roswell has a long history of aerospace testing and research.It contains what used to be called the White Sands Proving Grounds - where Werner Von Braun and his German team fired hundreds of reassembled V2s and other missiles in the late 1940s and 50s.
The third Space Shuttle mission also landed there (March 1982) - the only time in the Shuttle programme where the Shuttle didn't land at either Edwards Air Force Base or Cape Canaveral.
Hugo a Gogo said:
cross posted this Q from the wikipedia thread:
when they say he's going to go supersonic, is that breaking the sound barrier for the altitude he is at, or breaking the speed of sound at sea level, but at a higher altitude (so not actually breaking the sound barrier)?
Sound barrier for the altitude he is at, as he decreases in altitute the speed of sound increases as does temperature and air density. Mach 1 at 90000 feet is approx 670 mph, at sea level its approx 760 mph. when they say he's going to go supersonic, is that breaking the sound barrier for the altitude he is at, or breaking the speed of sound at sea level, but at a higher altitude (so not actually breaking the sound barrier)?
it's hard trying to google for info without getting all the 'soft' news stories, but from the redbull site it looks like he will be going 690mph at 100,000 feet
then this page
http://www.allstar.fiu.edu/aero/mach.htm
tells me that the speed of sound stays constant above 35,000 feet, I don't know how high you have to go for it to change again
so calculating from that, 660 is mach 1 at altitudes above 35,000 feet
edit: I was being daft there, thinking that the speed of sound is higher at altitude, of course it's lower
then this page
http://www.allstar.fiu.edu/aero/mach.htm
tells me that the speed of sound stays constant above 35,000 feet, I don't know how high you have to go for it to change again
so calculating from that, 660 is mach 1 at altitudes above 35,000 feet
edit: I was being daft there, thinking that the speed of sound is higher at altitude, of course it's lower
Edited by Hugo a Gogo on Tuesday 9th October 12:00
Hugo a Gogo said:
it's hard trying to google for info without getting all the 'soft' news stories, but from the redbull site it looks like he will be going 690mph at 100,000 feet
tells me that the speed of sound stays constant above 35,000 feet, I don't know how high you have to go for it to change again
Thats about right, 684mph would be mach 1 at 100k.tells me that the speed of sound stays constant above 35,000 feet, I don't know how high you have to go for it to change again
Above 40000 the temperature sticks to about -56c for quite a way up, which is why the speed of sound stays constant even though the pressure still continues to drop off a bit.
Can someone in the know talk to me about heat. He'll be high enough initially where the air is very thin but getting thinker all the time. The website mentions several times that the air gets thicker and thicker all the time, obviously, and that this will act as a brake..naturally. However, will he experience a buildup of heat.....or isn't he a) high enough and b) fast enough?
Not fast enough.
Re-entry heat - as experienced by returning spacecraft or satellites, is due to the speed of re-entry. An orbiting spacecraft will re-enter at 17,500 mph. A spacecraft returning from the moon (such as the Apollo Command Module) re-enters at 25,000 mph.
In 1951 the US Army launched a V2 with a top stage (called the WAC Corporal) to an altitude of around 300 miles (higher than the International Space Station orbits).
But it was a straight up - straight down flight and the "re-entry" speed never exceeded a couple of thousand miles an hour - not enough to cause the rocket assembly to burn up.
And these missions took place at White Sands
Re-entry heat - as experienced by returning spacecraft or satellites, is due to the speed of re-entry. An orbiting spacecraft will re-enter at 17,500 mph. A spacecraft returning from the moon (such as the Apollo Command Module) re-enters at 25,000 mph.
In 1951 the US Army launched a V2 with a top stage (called the WAC Corporal) to an altitude of around 300 miles (higher than the International Space Station orbits).
But it was a straight up - straight down flight and the "re-entry" speed never exceeded a couple of thousand miles an hour - not enough to cause the rocket assembly to burn up.
And these missions took place at White Sands
Edited by Eric Mc on Tuesday 9th October 12:30
I really really hope this goes well otherwise it will turn into an experiment about how the ground affects the human body at 690 mph.
which ironically might be a worthy experiment in itself.
I truly hope not though - I love the fact that people far braver then me are willing to still do this stuff! full marks..
which ironically might be a worthy experiment in itself.
I truly hope not though - I love the fact that people far braver then me are willing to still do this stuff! full marks..
It certainly is. And 25,000 mph is 7 miles per second - the escape velocity of the earth. If you can get a spacecraft to 25,000 mph, the earth's gravity will not pull it back - and it will leave the earth forever.
To put the speeds in perspective, imagine the energy that was needed to place the 100 Space Shuttle into a 200 mile high orbit at the required speed of 17,500 mph.
And imagine the energy required to send 30 tons of Apollo spacecraft on a lunar trajectory at the required speed of 25,000 mph.
To put the speeds in perspective, imagine the energy that was needed to place the 100 Space Shuttle into a 200 mile high orbit at the required speed of 17,500 mph.
And imagine the energy required to send 30 tons of Apollo spacecraft on a lunar trajectory at the required speed of 25,000 mph.
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