George Carty said:

One misconception I used to have (from watching Thunderbirds as a child) is that a sonic boom is only heard the instant an aircraft accelerates through Mach 1…

Heck, I was watching this just before high school when it appeared on WPIX-TV here in NYC in around 1968-69! Along with the X-20 mentioned above, I was even thinking of doing a book report on TB on rolling together equivalent real-life vehicles to see how close/far we were to creating a real IR! I’d like to see a science/engineering report doing something similar today just for interest sake since Popular Mechanics dropped that ball!

James Greenidge
Queens NY

        renevers said:

What did he do about the sonic boom in his helmet and ears?

Presumably nothing, since he would not have experienced any sonic boom. A sonic boom is a pressure wave, like a ship’s wake. The aircraft (or in the case the human) who is generating the boom is actually riding in the pressure wave and therefore does not hear the boom.

Anyway, there seems to be a misunderstanding by a lot of people about what a sonic boom actually is. A common misconception is that when you “break the sound barrier” there is a loud bang that happens once that sonic booms are produced by the aircraft or other body at a various instant.

That’s not how it is at all. There is a wave of pressure that travels along with the aircraft. This is continuous, just as a ship creates a wake as it travels, the aircraft creates a wake of air pressure. As the aircraft travels along it is doing this continuously. The reason it is a “boom” is to a stationary observer the sound of the change in pressure arrives all at once. You hear the boom as the aircraft passes.

A hot air balloon is about 3 million cu. ft. and just from looking at the redbull balloon on the ground, it seems to have about that size… but lets double it, to grant redbull the benefit of the doubt. On the ground the redbull balloon would be 6 million cu ft, but lets round up to 10 million cu ft. Air weighs about 1/100th of a pound per sq ft so I calculated that the amount of air displaced is 10,000 pounds. With these rough numbers, the configuration of a balloon with Felix in a capsule at about 7000 pounds, could have risen.

Half the atmosphere is under 8000 feet so air density would be half, at 8000 feet, so weight would be half. Thus the displaced air would weigh 5000 pounds. But Felix and the Capsule are still at 7000 pounds. The displaced air no longer weighs more than the configuration so it cannot rise any further. Felix would have stopped rising somewhere around 5000 feet. Most parachute jumps are done from around 10,000 feet but 5000 will do.

Based on this rough calculation, it appears to me that claims of having gone to 100,000 feet or more are not possible.

Rick Potvin
http://redbullhoax.blogspot.com/

Rick: These calculation is easier..
Helium has atomic/molecular weight= 4 g/mol , Nitrogen N2 =28 , Oxygen O2= 32.. Air is 80% nitrogen .So this gives that 4 kg of helium displaces 28.8 kg of air mixture . So about a factor 7.2 is the raise factor. Excluding its own weight :One =1 kg of Helium lifts net 6.2 kg of Balloon tissue ,construction and load. At the ground at 1 bar atmospheric pressure that is a reasonable small volume to store in the balloon. But when the balloon rises the helium must be able to expand as the pressure drops and the volume of the gas is bigger. The balloon cannot raise any further when all possible maximum volume in the balloon, is used up and overpressure begins. That is why the balloon is so saggy at bottom level, to have spare volume. It will be nice and round high in space. The balloon can leak Helium as well by porosity of the cloth tissue of the balloon, causing less lift than presumed. The balloon maximum volume is also, the pressure and so height determining factor.

Question .. Why using that expensive Helium ? .. Hydrogen is cheaper and is even lighter..(2) Baumgartner has a parachute and even a fire at 300m makes that he would survive , just by jumping out of the cabin. Was the balloon leaking that much ,that it would be a hazard? It is not a commercial zeppelin!

Question 2 : The press says, that Baumgartner fell faster that the speed of sound… But is that correct? Speed of sound is dependent on the density of the air and temperature and so on the pressure so on the height within the atmosphere. Ok for a jetliner on 11 km height it is about 1060 km/hr 295m/s.. But what for the speed of sound at the pressure at 32km to 25 km and where Baumgartner fell at some 372 m/s max speed, according to the press releases ? Has he surpassed the sound barrier TWICE (over it and under it again)? What did he do about the sonic boom in his helmet and ears?
I think that the extra air resistance, to approximate the speed of sound, could have prevented Felix to break it. But in thin air it is perhaps possible.
Between 39 and 35 km height ,he was still accelerating and could not surpass the speed of sound and between 35 and 11 km the speed of sound drops from 305 to 295 m/s . So it should have been near this speed. If he has broken S.O.S. it should have been near 35-30 km height with the low density air with low friction resistance break force for him.. It would be nice to see a speed and pressure diagram from the fall.

Anyway: 372 m/s is greater than the speed of sound on any height here, so if he reached that speed (how was it measured? GPS?), than he would have surpassed the sound barrier.

http://en.wikipedia.org/w/index.php?title=File:Comparison_US_standard_atmosphere_1962.svg&page=1

        Rick55 said:

The normal maximum height for weather balloons has to have already been calculated pretty carefully. The weather balloon is made of very thin plastic for a reason– it’s thin because they want the weight to be as small as possible. Breaching the design specs of the weather balloon by adding a felix-in-a-can seems, to me, to be nothing other than a good hoax. It seems plausible at first consideration but any deeper look at it raises questions.

The term “weather balloon” is a bit deceptive.

Originally unmanned balloons were used primarily for tracking winds and making basic meteorology measurements.

That’s really not what modern, large high altitude balloons do. They are designed to carry instruments to extremely high altitudes and are used for a variety of purposes, such as measuring cosmic rays, ozone levels etc.

Some of the payloads lifted by high altitude balloons are quite large. An example would be the Balloon-borne Large Aperture Submillimeter Telescope

http://en.wikipedia.org/wiki/BLAST_%28telescope%29

Another is the Cosmic Ray Electron Synchrotron Telescope.

These are not little boxes of barometers and thermometers. They’re big heavy pieces of equipment. So, yes, modern high altitude balloons can lift pretty big loads.

        Rick55 said:

Based on this rough calculation, it appears to me that claims of having gone to 100,000 feet or more are not possible.

Your estimates are in gross error: the balloon used was some 30 million cubic ft, not 10 million.

The flight data will be evaluated first by the Austrian Aeroclub (ÖAeC) since Baumgartner is an Austrian citizen and will then be confirmed by the Fédération Aéronautique Internationale. The chances of this being a fraud are therefore very low.

How does an HeBalloon rise in the first place? I’ve read that since the He is lighter than air, it will be buoyant and rise, according to Archimedes Principle. The amount of air displacement by the HeBalloon is such that it is pushed aside by the balloon volume, comes under the balloon and pushed the balloon up. This only works so far as the weight of the air is more than the combined weight of the He + balloon.

As the air becomes less dense, at higher elevations, two things occur. With a fixed balloon size, the weight of the displaced air becomes less. It’s therefore less and less likely to be enough to force the balloon ever higher. If the balloon expands, it will displace a bit more air but not much since the size of the expanding balloon is only compensating for the lower pressure. All things equal, the weight of the air should be about the same and thus the buoyancy would be the same. At some point the balloon would stop rising if the weight of the air is less than the combined weight of the balloon and He. IF the balloon has a weight attached (like Felix and the capsule), it would stop rising long before its design capacity. The balloon can only expand so much, as well, before bursting. The weight distribution on such a thin plastic balloon would have had to have been a problem too.

The normal maximum height for weather balloons has to have already been calculated pretty carefully. The weather balloon is made of very thin plastic for a reason– it’s thin because they want the weight to be as small as possible. Breaching the design specs of the weather balloon by adding a felix-in-a-can seems, to me, to be nothing other than a good hoax. It seems plausible at first consideration but any deeper look at it raises questions.

There are companies that now work on “sky crane” balloons that are helium balloons designed to lift the amount of weight represented by Felix and a capsule. But these companies are fairly new and their work-balloons are meticulously engineered for loads. The High altitude weather balloon was never designed for a big load and any engineer who spends any time thinking about this problem would instantly see that this is the case.

There are many angles to examine here but I would urge DC readers/contributors to consider Archimedes Principle first. The weight of the displaced air caused by the size of the Red Bull Balloon + the Capsule-with-Felix-in-it must be greater than that configuration for the configuration to go up. Even on the ground in Roswell, I don’t think that the weight of air displaced by the Balloon could have been greater than the configuration… which weight 6000 pounds.

A hot air balloon is about 3 million cu. ft. and just from looking at the redbull balloon on the ground, it seems to have about that size… but lets double it, to grant redbull the benefit of the doubt. On the ground the redbull balloon would be 6 million cu ft, but lets round up to 10 million cu ft. Air weighs about 1/100th of a pound per sq ft so I calculated that the amount of air displaced is 10,000 pounds. With these rough numbers, the configuration of a balloon with Felix in a capsule at about 7000 pounds, could have risen.

Half the atmosphere is under 8000 feet so air density would be half, at 8000 feet, so weight would be half. Thus the displaced air would weigh 5000 pounds. But Felix and the Capsule are still at 7000 pounds. The displaced air no longer weighs more than the configuration so it cannot rise any further. Felix would have stopped rising somewhere around 5000 feet. Most parachute jumps are done from around 10,000 feet but 5000 will do.

Based on this rough calculation, it appears to me that claims of having gone to 100,000 feet or more are not possible.

Rick Potvin
http://redbullhoax.blogspot.com/

        DV82XL said:

And now he is running his mouth on subjects he should know better not to: Felix Baumgartner: Mars is a waste of your tax dollars

I wonder how long before Red Bull pulls his chain and he will have to claim he was misquoted?

Wonder if NASA’s eating the praise they heaped on his “accomplishment”!

        DV82XL said:

And now he is running his mouth on subjects he should know better not to: Felix Baumgartner: Mars is a waste of your tax dollars

I wonder how long before Red Bull pulls his chain and he will have to claim he was misquoted?

I don’t know about that, I think he might well be right. Not that jumping from the upper atmosphere means very much either, but we could benefit from learning a lot more about the Earth. That said, I suppose learning more about Mars gives us comparison against our own planet.