(ORDO NEWS) — SpaceX has already worked out the way to return the first stage of rockets – it works. The second stages are still falling into the ocean, partially burning up in the atmosphere.
Startup Stoke Space took up the task of returning these steps to Earth and proposed a solution.
The decision came with a complete review of the very concept of the second stage, where, to save money, all those producing such rockets put one engine with fragile nozzles.
In the second stage of Stoke Space there will be 30 engines. Plus regenerative cooling of the hull.
Briefly about the history of the startup Stoke Space
BE-4 engine designer and Blue Origin BE-3 program director Andy Lapsa shares the vision of his former boss Jeff Bezos and SpaceX CEO Elon Musk that modern astronautics should come to cheap reusable rockets that can be sent into space at least daily.
However, the methods and pace of work of large private companies did not suit him.
So three years ago, with a small group of like-minded people, he founded Stoke Space, a start-up with the goal of building a new kind of fully reusable launch system.
After receiving initial funding in 2020, Stoke focused on the rocket’s second stage and developed a prototype engine, turbopump and built a manufacturing facility.
The staff was increased to 72 people. As a result, the final design of a fully reusable rocket with a payload capacity of 1.65 tons was approved.
Prototype test
In September, the company began testing the first prototype: a 4-meter-diameter ring with 15 individual engines attached to it.
This unusual design was the answer to the main problems that arise when the second stages return from orbit.
Typically, the upper stage of the rocket is equipped with a single engine with an enlarged nozzle to optimize exhaust gas flow in a vacuum.
As all parts of the rocket become as light as possible, the nozzles are too brittle to withstand reentry.
If you protect them with a thermal shield, the design will become too heavy and voluminous. Stoke engineers came up with another solution: a ring of 30 small thrusters.
In a vacuum, they work synchronously as one, and when entering the atmosphere, they turn on alternately. Protecting a smaller nozzle becomes easier.
Return of the second stage
The second important problem is the protection of the entire spacecraft from the temperature during landing.
On the shuttle, NASA solved this problem with fragile heat-shielding tiles that required 30,000 man-hours to inspect.
SpaceX is using a different type of ceramic coating. And the Laps team decided to resort to regenerative cooling of heat shields.
The rocket’s plastic outer metal shell is pierced with small cavities through which coolant flows.
If tests show that Stoke is able to land such an unusual upper stage, the team can move on to the development of the first stage and the problem of turning the rocket into an orbital spacecraft.
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