Updates on my experience at NARAM.
First, the The Cotton City Rocketry Club hosts were superb, can't thank them enough.
As to my HSR rockets, the ones where I used
@Dotini 's plastic fins WORKED. they were all BT-5 models, and VERY heavy for the A10-3T motor. They did obtain suprising altitude, I don't have an altimeter but easily over 100 feet. Descents were all horizontal, although no significant "hang time", they came down quickly but with no damage.
My designs with the cardboard tube fins were too tail heavy, I think I overbuilt the fins and the cans were so heavy that they all came in tail first, at best a 45 degree angle. I think I can build lighter and still have durability.
Since I don't think anyone else has laid out any groundwork, I propose that you
@Dotini should at this time be approving authority for the lingo. I will make proposals but I think it is your call. I do think lingo needs to be standardized, especially if this is to become a competition category for NARAM.
I propose
Abbreviations for Horizontal Spin Recovery (HSR) and Back Spin Recovery (BSR). Also,
@sr205347d consenting, for Belly Flop Recovery (BFR.)
"side-puff" be the official term for any Lateral port puff that throws off angle of attack. the ports would be "side-puff ports"
(Note from the Alway patent on Back Slider the following quote: " The side thrust may be generated by the ejection charge being vented through a hole or port in the body tube near the nose cone.")
"retro-puff" be official term for any forward directed puff which is meant to slow, stop, or reverse the forward rocket trajectory, and such ports would be "retro-puff ports."
I also propose that "true" HSR recovery be defined as that which has no structural change in rocket configuration between launch and recovery and the model recovers as a single piece. Aside from burned propellant and ejected gas and potential clay cap debris, nothing is ejected from the rocket. Means no nose blow, no chute, no streamer. Other than singed nozzle, the rocket should be picked up off the bround looking exactly like it looked on the pad, 'cept for maybe some grass stains, dust, or mud.
Okay, back to my experience.
The cut off nose hole for the "retro-puff port" worked fine. It has some pluses and minuses compared to to yours version.
Pluses.
It's just darn easy for PLASTIC cones. For a Vacu-Formed cone you can do it with a hobby knife, for a plastic cone a Dremel or equivalent would be easier.
You can size it however you like, if needed easy to make bigger, but can't make it smaller once you made it bigger.
It takes weight off the forward end of the rocket, in this case since you are mainly using the LENGTH of the rocket to shift the CG, the weight loss doesn't hurt although likely negligible.
Negatives
Likely a real DRAG, although I don't know how to calculate it. Not sure however how the drag from this compares to that from your "retro-puff ports"
If used with a VacuForm nose cone, the force of ejection might rupture the cone, since you won't/can't have a protecting bulkhead. I don't think this will be a problem for non-VacuForm regular plastic cones, but the weight of these cones might be a problem. My plastic cone above I got about a decade ago at an Apogee Garage sale, got 50 or 100 for about $10. I still have a pretty good stash. I didn't have my dremel at NARAM, so that was a rough tough cut with a hobby knife (fortunately bloodless, but close!)
Okay, some theory here.
Sounds like with SIDE PORTS you are not having 100% success with HSR (I'm not either, but I do better than with BSR.) If I think of a roulette wheel with equal numbers of red and black slots and ONE green slot, and I am getting on BOTH red and black, for HSR the wheel has 10 slots, for BSR 5 slots. Meaning the house wins and the rocket comes in ballistic 10% with HSR and 20% with BSR.
The problem is the transient rocket orientation after whichever puff you use (and possibly the rocket's velocity vector.)
If I understand it right, at least for HSR and BSR (not sure about Belly Flop Recovery [BSR],
@sr205347d gets it to work with NO puff but I don't get how), the TRANSITION depends on a significant deviation from near zero angle of attack (the world where Barrowman Equations work), to well OFF zero angle of attack (no, I don't have a number) where Center of Lateral Area (CLA, or cardboard cutout) works.
the big "No-No" for HSR and BSR is a Transient Post Ejection Orientation which is at or near NOSE DOWN when vertical velocity falls to zero (or worse, after the stable rocket arcs over and begins descending if ejection even occurs post apogee.) At this point, Gravity and Drag are the main forces on the rocket (I think Wind can be disregarded at this time.) If the rocket is NOSE DOWN, gravity pulls the rocket down nose first, the fins' drag keeps it tail up, and the rocket returns to STABLE linear (and in this case unfortunately BALLISTIC re-entry.) Note that for MOST rockets with failed ejection of the nose cone, the rocket is stable by BOTH Barrowman AND CLA calcs, so they will go "ballistic" regardless of orientation.
HSR and BSR rely on the rocket being far enough off "Nose Down" attitude that something ELSE happens.
For HSR, I think even with minimal "off nose down" attitude, the falling rocket causes the angled or curled fins with a little sideways force, enough to start the rocket rotating. I THEEENK the principle of conservation of angular momentum is what forces the FALLING rocket to turn toward the horizontal position (perpendicular to the vector of fall, so parallel to the horizon). The more it turns horizontal, the more fin surface the rocket "offers" to the airstream and the faster the rocket rotates. It's a positive vicious cycle, maximized when rocket is perfectly horizontal. Because of this, I think HSR tolerates more "near nose down vertical" position than BSR.
So with "side port-puff", the problem is that the post-puff orientation is completely random. So once in a while the roulette wheel lands on green, and rocket comes in ballistic.
Now, with your innovation of retro-puff, maybe it's a new ball game. Assuming at least a slightly short delay (yeah, that's gonna cost a bit of altitude), the puff occurs with the rocket presumably at or near vertical (there may be some weathercocking.) Next question is "how strong is the puff?" If it is enough to either STOP or REVERSE the upward trajectory, seems like the probability of the rocket starting to "fall" in a "nose-down vertical" (i.e., BAD) orientation is near zero, I think certainly far less than the completely random side port puff.
So am I correct that your success rate of transition to HSR has greatly improved with retro-puff? And if not 100%, do you have a good explanation for the failures?
Me thinks the retro-puff technique pre-apogee would be a GREAT technique for Back Sliders, as pausing mid-air at or nearly at perfectly nose UP should be the PERFECT orientation for transition to Back Slide (?
@Rktman what do you think?)
Okay, got to get to work on submitting the rules change to make Horizontal Spin Recovery a competition event. I'm leaning toward Duration rather than altitude for a couple of reasons.
1. Adding altimeter weight certainly doesn't IMPROVE reliability of transition.
2. The real challenge/cool part is the transition and hang time, rather than how high you can get it to go (and altitude is gonna help your duration anyway).
I will run my submission by you and
@BEC and
@Rktman before I submit it.