# The Naked Scientists Forum

### Author Topic: Is Redbull Stratos feasible?  (Read 3911 times)

#### Spannerman

• Jr. Member
• Posts: 26
##### Is Redbull Stratos feasible?
« on: 16/02/2010 16:54:05 »
World reknowned base jumper and extreme athlete Felix Baumgartner will attempt a project called Redbull Stratos later this year. If you have not heard about this you can read more here http://www.redbullstratos.com/ [nofollow].
Basically Felix will take a helium balloon up to 35km altitude, this is in the stratosphere, it is here that Felix accompanied with a space suit will sky dive. He hopes to break the sound barrier during his +- 5min 30sec freefall.

Is this at all possible? I know that he will be able to survive at the altitude but how will terminal velocity allow him to reach mach 1. He plans on doing this as a freefall so he will not be projected, please explain how he will reach the speed.

Also;

Shouldn't the sonic boom cause him to become unstable?

#### Spannerman

• Jr. Member
• Posts: 26
##### Is Redbull Stratos feasible?
« Reply #1 on: 24/02/2010 18:04:13 »
Okay so it is feasible, I calculated that he can reach a maximum speed (excluding air friction) of 828.3 m.s^-1
Does anybody know how to calculate the air friction/ resistance?
So if he does reach this speed does anybody know how he is going to stop?

#### Bored chemist

• Neilep Level Member
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##### Is Redbull Stratos feasible?
« Reply #2 on: 24/02/2010 19:53:11 »
"So if he does reach this speed does anybody know how he is going to stop?"
Well, I imagine he has a parachute.
If not then the ground will do the job. If he gets the aim right he would also save the cost of a burial too.
It's difficult to calculate the effect of air resistance, but one thing to note is that there's not a lot of air up there to resist his fall anyway. Also that air is cold and the viscosity falls with temperature (unlike most liquids BTW)

A fair approximation can be obtained from the Stokes equation
http://en.wikipedia.org/wiki/Stokes'_law
On the other hand, the last bloke
http://en.wikipedia.org/wiki/Joseph_Kittinger
did all those things and this guy plans to start higher so it's all perfectly plausible.

#### LeeE

• Neilep Level Member
• Posts: 3382
##### Is Redbull Stratos feasible?
« Reply #3 on: 25/02/2010 12:28:35 »
Joe Kittinger parachuted (free fall most of the way, of course) from 102800 ft (31.3 km) in 1960.  However, he used a small drogue chute for stabilisation at the start of the free fall, which would have slowed him down quite a bit.  He reached a max speed of 614 mph.

Interestingly, it seems that Joe Kittinger is advising Felix Baumgartner on his attempt.

#### Spannerman

• Jr. Member
• Posts: 26
##### Is Redbull Stratos feasible?
« Reply #4 on: 25/02/2010 15:00:01 »
Yes I did see that he was helping Felix out, what I thought was that the parachute would not be able to with stand the drag at that speed and would surely tear apart, would it be made out of a stronger material?

#### neilep

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##### Is Redbull Stratos feasible?
« Reply #5 on: 25/02/2010 17:29:59 »
would he not deploy the parachute until he has entered the ' regular' atmosphere and then friction will slow him down naturally to regular free fall speed ?

#### LeeE

• Neilep Level Member
• Posts: 3382
##### Is Redbull Stratos feasible?
« Reply #6 on: 26/02/2010 11:46:54 »
He will probably deploy either a ballute or small drogue chute to slow himself down before deploying the main chute.

#### The Naked Scientists Forum

##### Is Redbull Stratos feasible?
« Reply #6 on: 26/02/2010 11:46:54 »