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Red Bull Stratos – a supersonic flight from the stratosphere

The project and its pilot

Austrian Felix Baumgartner, a renowned B.A.S.E. jumper, had for quite some time viewed a spectacular jump from the stratosphere with the aim of becoming the first human to break the sound barrier in freefall as the culmination of his extreme sports carrier. From the outset, Joe Kittinger's much-famed record jump during the US Air Force Excelsior III mission on 16 August 1960 was considered the benchmark. Kittinger back then jumped off an open balloon gondola from an altitude of 31,333 m (102,800 ft), reaching a vertical top speed of 988 km/h.
Eventually, in 2005 the Stratos project evolved with the financial backing of Salzburg (Austria) based energy drink producer Red Bull. Though it became a huge technical and scientific endeavour involving a vast number of aerospace experts, in particular in and from the US, it has always been Baumgartner's brainchild.
Led by technical project director Art Thompson, the Red Bull Stratos team comprised well-known experts from various domains such as Mike Todd (life support system engineer), Dr. Jonathan Clark (medical director), Andy Walshe (supervisor on athlete high performance), Marle Hewett (senior flight test engineer), Luke Aikins (skydiving consultant), and Don Day (chief meteorologist) to name a few. In 2008 the team was joined by Joe Kittinger, retired Colonel of the US Air Force who has held several ballooning and parachuting records since 1960. Kittinger became an advisor to the project, Baumgartner's mentor, and eventually acted as communication interface to Baumgartner during the test jumps and the ultimate mission jump.
The Roswell International Air Center in New Mexico (USA) in 2011 became the homebase for the Red Bull Stratos mission, once the project entered into its flight test phase.

Test jumps

Preparations for the mission jump that was to allow the first human to become supersonic in freefall involved massive equipment testing. For example, the high-tech capsule, the custom-made pressurized suit with its life support system, helium balloons in different sizes, as well as state-of-the-art still and video camera gear that would document the attempted jump needed to undergo thorough testing, and of course demanded considerable financial resources.
Finally, in early 2012 the project entered into its ultimate rehearsal phase comprising two high-altitude manned test jumps, following two earlier unmanned flights conducted in December 2011 and January 2012, respectively.
Felix Baumgartner's first stratospheric test jump took place on 15 March 2012 from an egress altitude of 21,828 m (71,615 ft) over Roswell, New Mexico (USA). According to official data from the Fédération Aéronautique Internationale (FAI), Baumgartner during a freefall duration of 3 minutes and 40 seconds reached a top speed of 586.92 km/h (163,03 m/s or 364.69 mph), deploying his parachute at 2,503 m (8,211 ft) above sea level.
The second and final test jump took place in the same location on 25 July 2012. According to FAI data, the actual egress altitude this time was 29,610 m (97,146 ft), some 2,000 m higher than planned. He reached a top speed of 863.71 km/h (239.92 m/s or 536.80 mph) during a freefall of 3 minutes and 48 seconds, deploying his parachute at 3,930 m (12,894 ft) above sea level. The whole descent lasted 10 minutes and 36 seconds.

The record-braking jump on 14th October 2012

Exactly 65 years to the day when US Air Force pilot Capt. Chuck Yeager was the first to break the sound barrier in his rocket-powered Bell X-1 plane reaching a maximum speed of Mach 1.07, Red Bull Stratos took to the skies over Roswell, New Mexico (USA), on Sunday, 14 October 2012.
After the first scheduled launch window six days earlier (on Monday, 8 October 2012) had passed due to unfavourable ground winds, the second attempt on Wednesday, 10 October 2012, had to be scrapped when the helium balloon during filling was hit by wind gusts at the top of the balloon which partly forced it down on the ground potentially damaging its super-thin (0.02 mm) polyethylene foil. The first of two available balloon hulls was thus lost in that attempt.
With only one more, slightly larger balloon hull left the countdown for the final jump resumed on Sunday, 14 October 2012, at six o'clock in the morning local time.
Though the Red Bull Stratos team again had to wait for several hours in order to pick the right window for filling the almost 850,000 m³ large balloon with helium, everything went smoothly this time. At 9:29 hrs. local time the huge balloon with Felix Baumgartner's capsule suspended below performed a text book launch. The official target altitude for the mission jump was 35,576 m (120,000 ft). This altitude was considered to provide for sufficient margin for Baumgartner to actually break the sound barrier which, while being dependant on temperature, was calculated to be around 1,110 km/h (308.3 m/s) at 30 kilometres of altitude.
Due to the second balloon being larger than the one spent on the Wednesday before, it ascended to a peak altitude of 39,068.5 m (128,177.5 ft). The actual egress altitude according to final Red Bull Stratos data became 38,969.4 m (127,852.4 ft). After jumping from the capsule's doorstep, Baumgartner within some 34 seconds became supersonic, i.e. passed Mach 1.0 (equivalent to 1,115 km/h), at an altitude of 33,446.0 m (109,731.0 ft), still massively accelerating at this point. According to final Red Bull Stratos data, he reached a vertical top speed of 1,357.6 km/h (377.1 m/s or 843.6 mph) at an altitude of 27,833.0 m (91,315.6 ft) after 50 seconds spent in freefall, translating to a Mach number of 1.25! He then slowed down to subsonic speed at an altitude of 22,960.7 m (75,330.4 ft) after some 64 seconds into freefall. At that point a sonic boom could be heard and was indeed recorded on the ground. Based on these updated information, the supersonic section of Baumgartner's freefall amounted for exactly 10,485.3 m (34,400.6 ft).
The freefall duration was clocked at 4 minutes 20 seconds, interestingly short of Joe Kittinger's record set in 1960. However, Kittinger then descended with the assistance of a drogue chute that apparently extended his freefall. The Mach number achieved indeed topped even the most optimistic estimates which had anticipated a likely maximum Mach 1.17. The whole descent lasted a mere 9 minutes and 18 seconds, and Baumgartner deployed his main parachute at approximately 1,525 m (5,003 ft) above ground.
Felix Baumgartner successfully avoided the automatic deployment of a safety drogue chute during the fastest section of the freefall. This drogue chute would have been triggered by a G-force sensor once Baumgartner had been in a dangerous flat spin for more than six consecutive seconds at more than 3.5 G. Additional POV video footage, released one year after the successful jump, confirmed that Baumgartner was successfully battling violent flat spins after already being supersonic. Thus, the possible deployment of the drogue chute would likely not have compromised the mission's key objective, i.e. to become faster than the speed of sound during freefall. Baumgartner in interviews after the successful jump admitted not noticing the moment of going supersonic; he even wasn't sure whether he had accomplished his key objective. Part of the ground team, however, stated they heard the familiar sonic boom during Baumgartner's descent.
The full POV video indeed suggests that speeds above some Mach 0.85 are particular prone to causing flat spins. Baumgartner managed to fully stabilize his freefall while decelerating to Mach 0.86 at an altitude of some 19,500 m (64,000 ft).
The capsule safely landed 88 km away from the launch site after a 24 minute ride, while the balloon hull landed 11 km away from the capsule after a 15 minute descent. Both pieces of equipment were recovered by the team and immediately ferried back to Roswell airfield the same afternoon.

Summary of manned Red Bull Stratos missions

Stratos mission Date Helium balloon Launch
time
Egress altitude Max vertical
freefall speed
Freefall
distance
Freefall
duration
Parachute deployment Landing time Remarks
No. Designation   Volume [m³]
Volume [ft³]
Height [m]
Height [ft]
[UTC]
[local time]
[m ASL]
[ft ASL]
[km/h | Mach]
[mph]
[m]
[ft]
[s] [m ASL]
[ft ASL]
[UTC]
[local time]
 
 
1 First manned balloon flight 15-Mar-2012 34,547
1,220,000
39
128
14:10 hrs
8:10 hrs
21,828
71,615
586.92
364.69
19,325
63,402
220 2,503
8,211
15:50 hrs
9:50 hrs
target altitude was 70,000 ft; main objective was to fly over the 'Armstrong line' (ca. 19 km); pilot landed some 48 km away from Roswell
2 Second manned balloon flight 25-Jul-2012 150,079
5,300,000
64
210
12:00 hrs
6:00 hrs
29,610
97,146
863.71
536.80
25,680
84,252
228 3,930
12,894
14:20 hrs
8:20 hrs
target altitude was 90,000 ft; capsule substantially damaged during harsh landing
3 Mission jump / record attempt * 14-Oct-2012 834,497
29,470,000
102
335
15:28:37 hrs
9:28:37 hrs
38,969.4
127,852.4
1,357.6 | 1.25
843.6
36,402.6
119,431.1
260 2,567
8,421
18:16 hrs
12:16 hrs
target altitude was 120,000 ft; jump at 12:03 hrs local time; pilot landed some 70 km away from Roswell; capsule safely landed 23 minutes after Baumgartner
 
* Final data from the Red Bull Stratos Scientific Summit in Los Angeles, USA, published on 05-Feb-2013, and ratified by Fédération Aéronautique Internationale (FAI) on 22-Feb-2013; confirmed world records, as submitted to FAI on 15-Oct-2012, in bold
 

According to ratified FAI data, Felix Baumgartner has broken a total of three official world records for highest exit altitude (unofficial previous record: Joe Kittinger, USA, during the Excelsior III mission at 31,333 m on 16-Aug-1960), highest vertical speed in freefall (unofficial previous record: Joe Kittinger, USA, during the Excelsior III mission at 988 km/h on 16-Aug-1960), and longest total distance in freefall (previous record: Evgeny Andreev, Russia, on 01-Nov-1962 covered 24,500 m in freefall without the use of a drogue chute).
Further records, though not officially endorsed by FAI, comprise highest manned balloon flight (previous record: Malcolm Ross and Victor Prather, both USA, onboard the US Navy Strato-Lab balloon at 34,668 m on 04-May-1961), largest manned balloon flown at 834,497 m³ volume, and fastest speed of a manned balloon overland at 218.4 km/h (117.9 kn).
Though not officially claimed by Baumgartner, the record for longest duration in freefall without use of a drogue chute would also be with him.

Sources: Red Bull Stratos, FAI