In recent years, especially in the past, we have seen a certain boom in VTOLs (Vertical takeoff and landing) in order to create flying taxis that can become an alternative to today’s cars. But VTOLs have been designed for decades not only to travel a few miles, but reduce costs when traveling in space.
An example of these is the SASSTO, an original vehicle designed with something like a reusable space taxi as a simple and inexpensive alternative to what was being done. It arose amid the space excitement, when the United States intended to take giant steps to overtake Russia in this growing race by focusing on multistage rockets like Saturn V.
An idea that was a breeze of fresh air in the middle of the space race
SASSTO refers exactly to One-step application of Saturn in orbit, something like “Saturn Application for Orbit in a Single Stage”, and was born from the spirit of Philip Bono, an aerospace engineer specializing in structures and propulsion, who in 1947, just after completing his university studies, began working at North America Aviation, a former company manufacturing aerospace vehicles like the future Saturn V, which was at in turn Boeing’s main stock.
Philip Bono thought a single-phase vertical take-off and landing vehicle could compensate financially
After a few years and with the space race already a little more mature, Bono was already seduced by the idea of reusable space vehicles. In fact, Andrew J. Butrica classifies him as a “dreamer” in his book Single Stage to Orbit: Politics, Space Technology, and the Quest for Reusable Rocketry, about him in Chapter 5, titled “Space Visionaries”.
Based on this, and around the cost savings, he thought that in the meantime a multiphase rocket (like Saturn V) a vertical single-phase take-off and landing vehicle could compensate financially. In 1969, the year humans walked on the moon, he published Frontiers of Space, a book that includes explanations and beautiful illustrations from SASSTO.
What Bono considered was that the real success of the American space race had been the third phase of a Saturn V, called Saturn IVB (S-IVB). And with the idea of his one-stage VTOL, he developed the SSASTO, which became a vitamin S-IVB, with a hooded nozzle and powered by liquid oxygen and hydrogen.
“Houston, we have a problem”: details and curiosities after one of the most famous alarm messages in history
Very nice and inexpensive, but it has no wings!
The aerospace engineer participated in a series of studies to determine whether the cost of manned ballistic vehicles with vertical take-off and landing was competitive with that with vertical take-off and horizontal landing (which would be done by subsequent shuttles). Some have sprouted in this vehicle, designed to transport a payload of 2,812 kilograms and had a total mass of 97,887 kilograms.
The idea was to position the liquid oxygen tank at the bottom to minimize the difference between the center of aerodynamic pressure and the center of gravity. The diameter would be 6.71 meters and it would have a total length of 19 meters, with a take-off thrust force of 1,232.2 kilonewtons.
If it had materialized, SASSTO would have orbited 185 kilometers, capable of loading up to 3,629 kilograms, thinking of a ship of the Gemini program (precursor of Apollo) with two crew members and with a maximum stay of 48 hours.
1. Where would the Gemini capsule go?
2. Section to adapt the capsule.
3. Transition support structure.
4. Injection / control unit of the propellant tank.
5. Toroidal liquid oxygen tank.
6. Combustion chamber (ring).
7. Nozzle and thermal protection against reentry.
8. Tilt control system.
9. Retractable feet (landing)
10. Liquid hydrogen tank (spherical).
(Image and information: Projecthro)
The SASSTO costs were compared to two other horizontal landing models, but no attempt was made to meet the estimate of marginal landing costs due to too many unknown factors (and here SASSTO would compensate by not needing a runway as such). SASSTO’s estimated cost has reached $ 1.1 billion (so far), while the other two would cost between 50% and 2.2 times more, but it was calculated that in the long run it would be desirable to opt for more complex, heavier and winged vehicles, with higher loads and better handling in mind.
So while cost analyzes gave an advantage to vehicles without reusable fenders like SASSTO, the advantage seemed to diminish under heavy loads. According to Butrica, Bono’s feeling was that the biggest objection to SASSTO it was not so much technical, but psychological.
Oddly enough, the evolution of space vehicles seems to prove Bono right now that the era of shuttles has been gone for decades and it seems like reuse becomes more and more logical. We have current and recent examples such as the first stage of SpaceX’s Falcon 9 which has been reused five times. It’s not a one-step rocket, but somehow it seems after all of Bono’s ideas, other “dreamers” are applied.
Photos | Projectrho