Ever since Gemini 7 or the Space Shuttle era, fighter jet training has been at the heart of spaceflight. NASA Astronauts had to complete fighter jet training, as well as fly at least 15 hours per month if they are commanders or pilots scheduled to fly to orbit. The commander of Inspiration 4 and the Polaris Dawn mission, Jared Isaacman, is also betting on fighter jet training for his crew members. But why is this?
Space Agencies and also private space programs have been doing fighter jet training, not only for its similarities in experiencing several Gs, but for its high risk environment. Crews have to learn to work in high stress and high stake environments like they would experience during a rocket launch. They have to endure several times their own body weight pressing down on them, while communicating, going through checklists, and monitoring their ascent during launch.
History Of Fighter Jet Training In The USA
During the beginning of human spaceflight, hardly any NASA astronaut has not been a test pilot for a branch of the US military. Being an astronaut in the early days of NASA basically meant you had to have experience flying fighter jets. That was not coincidence, but a criteria for becoming an astronaut. Throughout the different human spaceflight programs, NASA kept fighter jet training as a mandatory part of astronaut training. During the Space Shuttle era, every single crew member had to go through fighter jet training and NASA even required at least four hours of stick time in a T-38, with 15 hours per month for commanders or pilots. That meant that even civilian mission specialists that would never find themselves at the controls of a Space Shuttle had to record flight time.
The T-38 was not only good for that, but also for simulating the approach and landing of a Space Shuttle for the commanders and pilots. NASA’s T-38s were equipped with an extra large set of air brakes on the bottom of the aircraft and had its landing gear deployed to best simulate the flight characteristics. The T-38s were not only useful to train for Space Shuttle missions, but actually supported them as they could fly along the Space Shuttle during final approach to provide visual confirmation that there were no hydraulic leaks and the gear deployed fully. They could even communicate visually with the crew inside the Space Shuttle if necessary.
To improve the training experience, NASA employed the Shuttle Training Aircraft (STA), the C-11A, which was a modified Grumman Gulfstream II. The commander’s side was equipped with Space Shuttle controls and instruments, while the instructor pilot’s side used more conventional controls. To simulate the Shuttle’s flight characteristics, the main back landing gear was deployed at around 11 km altitude (not the nose gear as it couldn’t handle the loads) to induce more drag. Furthermore, the flaps on the C-11A could deploy in the opposite direction to reduce lift on the wings and crews flew with the jet engine’s thrust reversers deployed during landing. It took all this to simulate the Shuttle’s very poor flight characteristics as good as possible.
An Imperfect Match
Despite fighter jets not being a perfect analogue for flying on rockets, they teach the crew what it takes to work in high risk and high stress environments. Although you can reach high G loads in both a fighter jet and a crew capsule during a rocket launch, they can’t be compared as they are experienced along a different plane.
When flying on a rocket, astronauts are basically lying on their backs throughout the ascent phase, compared to pilots in a fighter jet sitting upright. Astronauts experience a relatively gradual push all the way along their back, feeling gravity increase over time. Although a fighter jet can pull lateral Gs (forward and backwards in relation to the passenger), pilots mostly feel centripetal acceleration when banking or pitching the aircraft hard. The Gs are experienced more as a compression than a push along one’s back. It will push one’s blood down into the seat rather than into the back of the seat.
An everyday example of this would be the forces experienced on a roller coaster ride. It’s because the person on a roller coaster and the vehicle they’re traveling in have inertia. When that vehicle changes direction, the person’s inertia wants to just continue in the direction they were traveling forcing the person’s body against the side of the cart. Same applies to a typical slingshot, where one spins a rock in the sling at high speeds. Once the sling is released, the stone will keep going in the direction it was last traveling due to its inertia.
Similar to what SpinLaunch is planning to do with its launch vehicle. They will accelerate their vehicle inside a large centrifuge pulling over 1000 Gs. Once they release their rocket, it will travel about 8,000 km/h up into the sky, the direction it was last traveling.
A better analogue for lateral G forces experienced in the early portions of a rocket launch is probably a ride in a Tesla Model S Plaid as it will push one’s body back into the seat while accelerating. It does that with more force than gravity pulling down on you, meaning that if the Tesla would not have a floor, one would not fall through, but be pushed into the back of the seat. The longer a ride on a rocket takes, the more it accelerates and therefore more Gs are being experienced by the crew in the capsule until the engines gradually throttle down to maintain a maximum G load up until they stop firing.
Fighter Jet Training For Polaris Dawn
Jared Isaacman, the individual behind the Polaris Program is performing fighter jet training with all his crew members for the aforementioned reasons. When pushing the boundaries of human spaceflight by performing the first commercial EVA, Isaacman believes that training his crew in his fleet of fighter jets is crucial to the success of the mission. He does that with his private fleet of jets and allowed a selected group of space journalists and science communicators to experience what he and his crew experience during fighter jet training.
Polaris Dawn will be flying on a SpaceX Crew Dragon Capsule in 2023 and during which it will perform the first EVA in SpaceX’s history, which means they’ll depressurize the whole vehicle, open the docking port and float out into space, similar to early Gemini or Apollo missions.
During the event, Jared “Rook” Isaacman and Scott “Kidd” Poteet took individuals to the sky in the same jets that the Polaris Dawn crew trains in.
|Mikojan-Gurewitsch MiG-29||Dassault/Dornier Alpha Jet||Aero L-39 Albatros|
|Engine||RD-33||SNECMA Turbomeca Larzac||TFE-731|
|Number of engines||2||2||1|
|Role||fighter jet||jet trainer / light attack jet||jet trainer|
|Top speed | Mach||2,446 km/h | 2.3||995 km/h | 0.80||750 km/h | 0.61|
|Max. G load||9||8||8|