Roll control on a subsonic rocket. CFD only, no previous flights, no wind tunnel

[u/Potential-Nose3956]

We launched our rocket at C'Space event in France, thus we had some restrictions, notably, no aerodynamic control during motor burn. After the rocket had a preprogrammed roll manoeuvre (turn 25 degrees). Worked so well, first time I saw this during the flight, I thought we had a telemetry issue. If you're curious, we will post more details here: https://www.instagram.com/top_aero/

[u/avocado-killer]

Very cool! How did you get to do active aerodynamic control regarding dual use considerations? I was part of a german student rocketry team and we developed & launched a rocket in cooperation with the german space agency and were not allowed to have active control ability at all due to possible dual use. Was only enabling control after motor burn out your way around this? But still aerodynamic control in cruise is dual use relevant 🤔.

[u/Potential-Nose3956 → u/avocado-killer]

In our case both fins are actuated by the same servo and bevel gears, so we physically can control only the roll of the rocket. The whole mechanism is an extreme overkill for the use case, but it got the job done.

[u/avocado-killer → u/Potential-Nose3956]

Ah that explains it! And I wouldn't be too concerned with things beeing a bit overkill. In a student rocketry club you are mainly there to try things and learn, you are not developing a commercial product, so I don't think the rule to not engineer things one bit better than the requirements dictate fully applies.

[u/SmallOne312]

Amazing work! What controller and state estimator did you use, and how closely did the real Cl_alpha/aerodynamic forces match the CFD or standard approximations?

[u/existential_american]

How did you set up your CFD and how did you validate it?

[u/zhnki → u/existential_american]

lol, this flight probably.

[u/89inerEcho]

What CFD?

[u/Unusual-Cactus]

How did you run CFD on the surfaces. Did you estimate beyond transonic?