ARCA Space's webpage for the Stabilo program has a description and an image. Hydrogen peroxide monopropellant? Reaction closer to the crew than the nozzle?

With thrust at the top, it seems that simplification due to inherent stability is a big advantage no, per @RussellBorogove's comment that's not right. While the word "Stabilo" appears frequently, the "aerodynamic stability system at the top" does not refer to any passive stabilization due to thrust-at-the-top at all. It's something different entirely.

Why was the thrust put at the top, and how was the attitude controlled during the phase of descent that used this engine?

Also, wasn't it tempting to use all that free oxygen to get a boost from combustion? Or was that going in the wrong direction - adding complexity where simplicity was sought?

The problem with steam is that it condenses, shrinking by a factor of roughly 1000 in volume. Was it difficult to ensure that the steam was always above its local boiling point (noncondensing) at each location and pressure, at least until well outside of the nozzle?

enter image description here

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    $\begingroup$ Thrust at the top doesn't give any stability advantage. en.wikipedia.org/wiki/Pendulum_rocket_fallacy space.stackexchange.com/questions/9682/… $\endgroup$ Apr 2, 2017 at 8:48
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    $\begingroup$ I don't think it did work. They appear to have dropped this approach in favor of other speculative designs. $\endgroup$ Apr 2, 2017 at 15:31
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    $\begingroup$ Maybe it'd be better to phrase the question "how was X supposed to work?" rather then "how did X work?" given that it seems to have never actually launched. $\endgroup$ Aug 9, 2019 at 20:36
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    $\begingroup$ Stabilo did refer to passive stability due to use of tractor engines (with the claim that towing a mass on a cable magically made it work). They even named it the "Popescu-Diaconu stabilization method", and hyped it up quite a bit early on. They're better at getting investors to give them money than they are at building rockets. $\endgroup$ Aug 9, 2019 at 22:35
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    $\begingroup$ Building a lot of them hasn't made them good at building them. They can't even run their steam rocket above 1.85 bar (no, I didn't put the decimal in the wrong place) on the test stand because its tank leaks, and what comes out is a weak spray of steam and liquid water that barely makes the vehicle bounce in its suspending cables. They launch infrequently because their designs and fabrication are both incompetent. $\endgroup$ Dec 19, 2020 at 0:57


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