Capitalism in space: Another new rocket startup, Stoke Space, is working to develop a new innovative reusable design for its upper stages.
Most commonly, a traditional rocket has an upper stage with a single engine. This second-stage rocket engine has a larger nozzle—often bell-shaped—to optimize the flow of engine exhaust in a vacuum. Because all parts of a rocket are designed to be as light as possible, such extended nozzles are often fairly fragile because they’re only exposed above Earth’s atmosphere. So one problem with getting an upper stage back from Earth, especially if you want to use the engine to control and slow its descent, is protecting this large nozzle.
One way to do that is to bury the engine nozzle in a large heat shield, but that would require more structure and mass, and it may not be dynamically stable. Stoke’s answer was using a ring of 30 smaller thrusters. (The tests last month only employed 15 of the 30 thrusters). In a vacuum, the plumes from these nozzles are designed to merge and act as one. And during reentry, with a smaller number of smaller thrusters firing, it’s easier to protect the nozzles.
Will this company succeed? Who knows? It is presently very early in development. However, that its founders are former engineers from SpaceX and Blue Origin is encouraging, especially based on this comment about why the Blue Origin guy, Andy Lapsa, left that company:
“I love Jeff [Bezos]’s vision for space,” Lapsa said in an interview with Ars. “I worked closely with him for a while on different projects, and I’m basically 100 percent on board with the vision. Beyond that, I think I would just say that I will let their history of execution speak for itself, and I thought we could move faster.”
Lapsa apparently was part of the exodus of high level managers and engineers that occurred at Blue Origin after Bezos hired Bob Smith as CEO. All complained of the company’s far-too-cautious management style under Smith.
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