- Mar 2, 2021
- Reaction score
- Seattle, Washington
I agree that sims are very valuable for many people. But it would seem that at least on one flight one of my rockets has grossly outperformed what the sim forecast. This possibly could be a freak motor, so I will need to do more tests to confirm that. But in no way am I claiming that ring fins are more efficient than planar fins - although they may be more durable and can fit into a smaller box. I do suggest that the present understanding and implementation of the ring fin and its performance envelope has not been sufficiently defined. I would greatly enjoy being a part of that conversation. But it takes two to have a conversation. Who else is building/testing ring fins on a rocket with ridiculously tiny support fins?Many people building typical 3FNC and 4FNC rockets have found sim programs helpful. As we get further from simple rocket designs, the sim programs, which are guesstimates to begin with, become less accurate. I never would have guessed that a launch lug is a MAJOR cause of drag, and while I may have guessed that an elliptical fin may be lowest drag in the subsonic speed range, a clipped delta is pretty close.
two possible questions here.
The first is whether your rockets outperform the expected altitudes from the simulation programs? Quite possibly true. I did not find that all together amazing.
however, if you are suggesting that ring fins are more efficient than planar fins I think that is something that would be great if it’s true, but it is not currently obvious. Then as I have mentioned many facts of rocket aerodynamics are not intuitively obvious to many of us mortal minded amateurs .
I am currently working on “Go With The Flow”, an air brake recovery rocket that theoretically should have infallible deployment, no pull bands, and self corrects with elastic brake/blade retention for early or late ejections .
but how about this? I will build a ring rocket to your specs, except I will initially build it with fins long enough to be stable without the ring. I will fly it 3 times with altimeter. I will round but not taper the forward and leading edges.
I will then cut off the excess outer hemispan of the fins and add the ring, so final rocket should be at your specs. Then weight the rocket, adjust if possible for any changes, and fly it again
would this be an acceptable test of your conjecture?
love to see you having fun, even cooler if you can turn rocket science on its ear!
Regarding the clipped delta; that is my favorite "normal" fin. Question: is the reversed clipped delta just as good at those subsonic speed?
Regarding your building a rocket to my specs and testing it: Yes! This makes me very happy. At last somebody takes this seriously. And I have no stake in my conjecture. Most likely, the sim program is defective when it comes to ring fins. Eventually, some one will fix it. In the meantime, I will try to make improved iterations of the concept. As you know, I have made some ring tails combined with boat tails, which seemed to be high flyers themselves. So one path of testing will be down the boat tail or "torpedo" approach, and another will be the simpler one with no heavy and complex boat tail to deal with.