Au contraire !
I am with
@Dotini on this one.
I suspect the lateral component of tube fins is by far the most effective segment (same is true for standard fins as well, but tube fins have a relatively large lateral component unique in that it is relatively parallel to body tube, as opposed to standard fins which are perpendicular.)
if you were to use a sweep, I suspect the most bang for your buck would be a neutral forward edge with a backward delta on the rear edge, with the caudal tip of the delta on the OUTSIDE edge (although this does make it more prone to breakage unless you go rear eject.)
interestingly this set up may place the nozzle plume partially inside the fins. My MindSim wonders if this might augment/improve the efficiency of the fins. (Since forward end is open, this may be the Anti-Krushnic effect.)
Also, by putting the sweep further back, my understanding of rocket physics says the further back the surface area, the greater the effect on CP (more efficient.)
the data that says that tube fins have the same drag per surface area but are less efficient is interesting.
certain segments of tube fins, particularly those abutting Each other placed circumferentially around the body tube (the classic/easiest is 6 tube fins same diameter as the central tube) are understandably ineffective, particularly those that abut the central tube and those that abut each other where Two sides abut each other that segment likely acts as a single piece RE center of pressure, but since double thick causes more drag.
@neil_w or anyone in peanut gallery, is there any recognized name for the ring rocket attachments to the main body? I guess you could call them struts or spokes, but when they are long and thin (basically just like regular fins, except somebody glued a ring on the end), they have two effects.
first, they DO function simply as fins themselves (unless you make them with extremely short chords). Unless the ring is unduly heavy, which may occur with a 3D Printed ring, if the rocket is stable with just the spokes without the ring, it will be likely stable with the ring. If the ring is a lightweight material like the rings
@neil_w and
@Rktman make out of balsa, the ring will likely greatly increase/improve stability Margin.
second, depending on how many you have, they subdivide or segment the ring into noncylindrical “Tubes”. For two or fewer spokes, probably the spokes have little effect on airflow. Somewhere starting I am guessing between 3 and 6 spokes, the spokes themselves constrict the cross sectional area of the “tube” and start causing both an increase in drag and probably a decrease in effectiveness (approaching the “closed cylinder” equivalent of a long tube fin), at a certain point depending on the chord of the ring and the number of fins, as the latter approaches infinity (and likely a far smaller number, like 8-20) the ring probably acts as a closed disc.
I suspect this is very difficult for sim programs to “comprehend” and therefore accurately simulate.
