Horizontal Spin Recovery - with Magnus Effect?

[Dotini]

I like!
Is this a two stage?
Is there more than one launch lug?
Are those 3D plastic or cardboard tubes?
Canards are interesting. If this is NOT. A two stage, From an efficiency standpoint, I am wondering whether you would get just as much rotational efficiency with much LESS drag and much MORE stability simply by lengthening the root of the main fins, so enlarging the surface area of the main fins to equate the additional surface area of the canards.

definitely provides its own major cool factor. Kind of has a Picasso Meets Mars Snooper look.

Answers:
This is not a two stage. At present there is only one launch lug, but there is another yet to install at the CG. The tubes are cardboard from Apogee. Since the canards are parked at the CG and the rocket is 50:1, stability is not yet a major concern. With specific regard to rotational efficiency and drag, I'm not qualified to remark. I'm an isolated experimenter trying to work step-by-incremental step from known, proven successful examples from the literature or my experience. This thing could be a hopeless flop and I'm back to working decals on my Estes Generic E2X.

Being even remotely compared to Picasso or Van Milligan is of course intensely flattering but highly unwarranted. Bizarre appearance results from my own Dogpatch engineering and workmanship, and not from any known artistic ability or formal training in this field.

 

[Dotini]

All components laid out, ready for testing. Not a museum quality build, but will hopefully be sturdy and visible.


Magnus X-3

Including B6-2 and all tape, weight is 2.34 oz with puffer cone, 2.52 oz with ejected cone and streamer. CG is under the canards with either cone.

First flight, tomorrow morning, weather permitting.

 

[BABAR]

You and I are going in radically different directions. Mine is gonna look more like a fire plug with little "pluglets" for fins. Variety is the spice!

 

[Dotini]

You and I are going in radically different directions. Mine is gonna look more like a fire plug with little "pluglets" for fins. Variety is the spice!

I'm not sure that we're going in radically different directions, but are merely pursuing different experimental paths to arrive at the common destination of horizontal spin recovery.

I do agree that a fat tube could be a big advantage. My working assumption is that hang time in the air after apogee for the horizontal spin recovery rocket is going to be a function of spin, diameter, length, weight, altitude and wind. That's a complex equation to solve. Just now, I'm trying to economically explore ways to maximize spin rate. My next experimental rocket, X-4, should I choose to make it, will attempt to maximize diameter as well. Greater size implies greater weight, power, and expense. A 24mm motor will be needed. I want to approach this judiciously, since I may have to move my flight operations to a larger field farther from home base.

 

[Dotini]

After warming up with an E2X and Animist II, we launched Magnus X-3 at Dahl field this morning in zero wind. The very 1st flight (with cone ejection) was beautiful. Altitude 433 feet and descent from apogee in 24.2 seconds, or 18 feet per second.

 

[BABAR]

Cool, looking forward to vid.

I am wondering, would strakes along the sides improve or detract from the Magnus effect?

 

[Dotini]

Cool, looking forward to vid.

I am wondering, would strakes along the sides improve or detract from the Magnus effect?

The vid was taken by stationary mounted camera, and didn't show much, but did convey sounds and timing. Blair's role this time was to track the rocket with the Estes Altitude Tracker, with which he is trained and practiced, and to also operate a backup stopwatch. We had carefully set up a 250' baseline, accurate to the inch. The session came to an end prematurely, as an improperly installed fin popped off on landing. So acceptable video will have to wait a week or so, after repairs and my fishing cabin time. A whole team of training soccer players stopped and marveled as my rocket spiraled lazily in the motionless air, one guy exclaiming excitedly about how it was horizontal the whole way down, shouting, "Rockets don't do that!".

About strakes, my untutored understanding is that they are meant to channel and condition air to the fin in boost mode. I imagine that they cannot hurt in horizontal descent, but only help (to a small degree) in adding spin. Obviously they have the valuable secondary benefit of adding structural strength to the tube.

 

[BABAR]

The vid was taken by stationary mounted camera, and didn't show much, but did convey sounds and timing. Blair's role this time was to track the rocket with the Estes Altitude Tracker, with which he is trained and practiced, and to also operate a backup stopwatch. We had carefully set up a 250' baseline, accurate to the inch. The session came to an end prematurely, as an improperly installed fin popped off on landing. So acceptable video will have to wait a week or so, after repairs and my fishing cabin time. A whole team of training soccer players stopped and marveled as my rocket spiraled lazily in the motionless air, one guy exclaiming excitedly about how it was horizontal the whole way down, shouting, "Rockets don't do that!".

About strakes, my untutored understanding is that they are meant to channel and condition air to the fin in boost mode. I imagine that they cannot hurt in horizontal descent, but only help (to a small degree) in adding spin. Obviously they have the valuable secondary benefit of adding structural strength to the tube.

Rockets that are unstable post ejection but without a normal chute or streamer or with incompletely deployed airbrakes or rotors or in this case a popped fin often have interesting and often quite gentle tumble recoveries in the low power world. I have no experience but from my reading the high power world is somewhat less forgiving.

the point of the strakes was wondering if the “rougher” outer surface when HORIZONTALLY spinning would move more air, and thus induce more Magnus effect. my guess is NO, because it would likely do bad things to the boundary layer, but at that point my aerodynamic understanding goes ballistic, and not in a good way,

 

[BABAR]

Anyway, sounds like a neat flight, and obviously the up part worked.

I am wondering if there is a maximum rotor surface area that when exceeded actually slows the rocket spin.

 

[Dotini]

Anyway, sounds like a neat flight, and obviously the up part worked.

I am wondering if there is a maximum rotor surface area that when exceeded actually slows the rocket spin.

#1) I know nothing.
#2) My guess is that at some point the mass, inertia and drag of an overly large cylinder are going to impede the work of the fins in spinning it up. Where that point is, we need to establish.
#3) My question is if spin is induced solely by the rocket falling down through the air after apogee, or if side winds do more than carry the rocket laterally and play some/any role in adding/maintaining spin.

 

[Dotini]

We will ty to launch morrow from Dahl field, weather permitting.

Left to right: Magnus X-3 with alternate cone section, Magnus X-2 with Blair's 4-way tangential rotary puffer, the parts salvage backslider, X2C, and Animist II, a ringtail fantasy scale UFO (streamer recovery).

Agenda will include video and descent rates.

 

[Dotini]

 

[Dotini]

CONCLUSIONS​

After numerous testing sessions with 3 horizontally spinning rockets (Magnus X-1, 2 and 3) and 1 non-spinning horizontal backslider, I have reached some tentative conclusions:

#1 and most important: a horizontally spinning rocket will have a significantly slower descent rate than a rocket of similar weight, power and length than one which is descending horizontally but not spinning. This is up to a factor of double or more the amount of time in the air. In my humble opinion (please correct me if I'm wrong), this difference can only be attributed to the Magnus Effect.

#2: A side puffer works well (even one which puffs equally in all 4 directions!), but so does cone ejection. Rocketeer's preference.

#3: On a windy day, there will be a greatly enhanced chance of losing the rocket with horizontal spin recovery.

#4: It has an astonishing effect upon spectators.

#5: Fins are challenged greatly upon landing. PETG plastic works very well indeed for this task, but paint will not last terribly well.

#6: 50:1 or 30:1, it didn't seem to matter a whole lot.

#7, last but not least: The ejection charge delay is of crucial importance. I got my best results with a B6-2.

 

[BABAR]

Interesting!

did your extra canards make much difference?

does conclusion 1 account for weight of rocket and casing and surface area of fins? Don’t get me wrong, I would LOVE to see Magnus effect provide vertical (aka useful) lifting force, just can’t wrap my head around the physics.

 

[Dotini]

Interesting!

did your extra canards make much difference?

does conclusion 1 account for weight of rocket and casing and surface area of fins? Don’t get me wrong, I would LOVE to see Magnus effect provide vertical (aka useful) lifting force, just can’t wrap my head around the physics.

The way I see it, the more you can measure and quantify a thing, the more you learn and know about it.

I timed the descent rate of several horizontally descending rockets, and found that rapidly spinning (several hundred rpm) rockets took substantially longer to come down. I am a hobbyist, and not a physics teacher. My experiments in this recovery method are concluded, and I'll be moving on to a different bowl of cornflakes.

 

[BABAR]

Well done! I guess you are a Cereal Rocket Designer!

 

[Dotini]

Well done! I guess you are a Cereal Rocket Designer!

Thanks, but no, I'm no designer. All the ideas and features seen in my rockets have been copied, borrowed or adapted from existing sources. I'm a simple, isolated 73 year old hobbyist, but also a born-again rocketeer.

 

[neil_w]

I'll repeat my suggestion that you submit your best-performing design to Tim at Apogee for publication in Peak-of-Flight. It takes some work to prepare it but it's cool to be published.

If you're inclined to give it a try, send him an initial inquiry with pics and description to confirm his interest before going whole-hog on the documentation.

 

[Dotini]

I'll repeat my suggestion that you submit your best-performing design to Tim at Apogee for publication in Peak-of-Flight. It takes some work to prepare it but it's cool to be published.

If you're inclined to give it a try, send him an initial inquiry with pics and description to confirm his interest before going whole-hog on the documentation.

Thanks, that's a very flattering idea, but probably one that I shouldn't pursue. I have no training in rocketry or physics, and I don't use a computer program. If my feeble, halting and tattered experimentation has any merit, then individuals or teams with credibility and resources will perform additional experiments to verify whatever it is I have stumbled upon, if anything. Frankly, I am growing weary of this recovery system, and need a break with lighter duties. What I need might be more oddrocs back at the Carkeek Park model airplane circle, and less controversy. I'm not seeking publication or notoriety, just peacefully having a few moments of joy.

 

[neil_w]

Thanks, that's a very flattering idea, but probably one that I shouldn't pursue. I have no training in rocketry or physics, and I don't use a computer program. If my feeble, halting and tattered experimentation has any merit, then individuals or teams with credibility and resources will perform additional experiments to verify whatever it is I have stumbled upon, if anything. Frankly, I am growing weary of this recovery system, and need a break with lighter duties. What I need might be more oddrocs back at the Carkeek Park model airplane circle, and less controversy. I'm not seeking publication or notoriety, just peacefully having a few moments of joy.

Up to you, of course. But don't worry about the stuff you said there at the beginning. If you have a design that works, and he finds it interesting, he'll publish it. It's just a recreational thing. And $50 credit at Apogee ain't bad.

But again, do what you enjoy, that's what the hobby is for.

 

[Rktman]

Thanks, that's a very flattering idea, but probably one that I shouldn't pursue. I have no training in rocketry or physics, and I don't use a computer program. If my feeble, halting and tattered experimentation has any merit, then individuals or teams with credibility and resources will perform additional experiments to verify whatever it is I have stumbled upon, if anything. Frankly, I am growing weary of this recovery system, and need a break with lighter duties. What I need might be more oddrocs back at the Carkeek Park model airplane circle, and less controversy. I'm not seeking publication or notoriety, just peacefully having a few moments of joy.

Really enjoyed this thread. It piqued my curiosity as was entertaining because your investigation (which it was, much more than just tinkering) was very thorough and methodical IMHO. Also you and @neil_w have got some mad craftsmanship and creativity skills. My builds just seem to plod along forever. Anyhow, looking forward to whatever else you might be creating in future threads.

 

[Dotini]

All components laid out, ready for testing. Not a museum quality build, but will hopefully be sturdy and visible.

View attachment 462094View attachment 462101View attachment 462093
Magnus X-3

Including B6-2 and all tape, weight is 2.34 oz with puffer cone, 2.52 oz with ejected cone and streamer. CG is under the canards with either cone.

First flight, tomorrow morning, weather permitting.

@PeterAlway
I'm bumping this thread to bring the esteemed Peter Alway into the conversation. There are some amateurish but still interesting videos to be seen here, as well as a chronicle of my bumbling experiments in Magnus Effects.

 

[BABAR]

@PeterAlway
I'm bumping this thread to bring the esteemed Peter Alway into the conversation. There are some amateurish but still interesting videos to be seen here, as well as a chronicle of my bumbling experiments in Magnus Effects.

You are far too modest. I will be interested in Peter’s opinion, but you may be the first to have demonstrated a Magnus force on a rocket on video. Or it may just be that these techniques have been dormant for a couple decades and needed new champions!

 

[mooffle]

I would not call your experiments bumbling at all. It's certainly fascinating stuff.
Maybe I just can't tell the difference because most experiments seem to be bumbling, thats just what makes them experiments.

Or it may just be that these techniques have been dormant for a couple decades and needed new champions!

I think this is the case, it was certainly time for someone to take up the mantle of odd recovery, only base foundations were there from what I can tell. Anyone remember when helicopter was new? Seems like so many variations are out there now.

 

[Dotini]

I would not call your experiments bumbling at all. It's certainly fascinating stuff.
Maybe I just can't tell the difference because most experiments seem to be bumbling, thats just what makes them experiments.


I think this is the case, it was certainly time for someone to take up the mantle of odd recovery, only base foundations were there from what I can tell. Anyone remember when helicopter was new? Seems like so many variations are out there now.

Thanks for your encouragement! I've decided to slowly continue experiments in Magnus effects, but with a BT-5 model as well as my trusty X-3. My search for a proper video camera continues, and my assistant is now back in town.


BT-5 based backslider in fin unit jig, to be built according to the Alway design, but with 4 "curly" fins for spin. Note big coupler from Totally Tubular. This model will receive no paint - except for the nose cone. Visibility accents will come from Sharpie.

 

[BABAR]

Thanks for your encouragement! I've decided to slowly continue experiments in Magnus effects, but with a BT-5 model as well as my trusty X-3. My search for a proper video camera continues, and my assistant is now back in town.

View attachment 469257
BT-5 based backslider in fin unit jig, to be built according to the Alway design, but with 4 "curly" fins for spin. Note big coupler from Totally Tubular. This model will receive no paint - except for the nose cone. Visibility accents will come from Sharpie.

This will be interesting. The definite commonality between Horizontal Spin Recovery (HSR) and BackSlider Recovery (BSR) is the horizontal orientation of the rocket on descent. For the HSR, the main effect on reducing vertical descent velocity (the main “goal” of all recovery systems) is forcing the rocket into a high drag orientation.

for the BSR, I am less certain. We call it a glide, and it LOOKS like a glide, it with either flat or neutral air foiled fins, no wings, and a neutral if not even slightly NEGATIVE angle of attack, I am having trouble determining if there is any actual LIFT being generated (@Rktman and @PeterAlway and @burkefj and anyone else from the peanut gallery feel free to chime in here.). Specifically, is the relatively slow descent of the BackSlider a Glide effect or just DRAG from being horizontal?

the “true” or “pure” BackSlide Recoveries (as I define them, no chute or streamer, no physical change in rocket configuration, nose cone STAYS in place) are definitely picking up significant lateral velocity. My total number of successes is (I think) 10, with three lawn or asphalt darts. 9 of the 10 descents were arrow straight lateral, one had a very nice gentle curve which was both fortunate as it kept it out of trees and likely dumb luck.

@Dotini, if this current approach DOES work, you have two potential hazards to fins. As you can expect, the rapidly rotating fin can slams at least one fin LATERAL SIDE on the ground at impact. The SECOND one if this DOES develop the horizontal trajectory and velocity expected in BackSlide recovery is a second impact vector impacting on the TAIL END of at least one fin.

maybe the 3D printer gurus (@cwbullet ?) can chime in here, seems like the perfect (or at least best) solution IF you go with symmetrical fins would be a single piece solid fin can with plastic fins stiff enough for low power flight but flexible enough to “bounce” on impact. I have absolutely zero knowledge on 3D constructions and materials, so I don’t know if this is possible/practical.

 

[cwbullet]

maybe the 3D printer gurus (@cwbullet ?) can chime in here, seems like the perfect (or at least best) solution IF you go with symmetrical fins would be a single piece solid fin can with plastic fins stiff enough for low power flight but flexible enough to “bounce” on impact. I have absolutely zero knowledge on 3D constructions and materials, so I don’t know if this is possible/practical.

This is possible. The key is testing and finding the right filament.

 

[cwbullet]

View attachment 462894

Can I get a photo from the bottom of each rocket?

 

[Dotini]

Can I get a photo from the bottom of each rocket?

Views of Magnus X-2 showing extensive damage to paint at base of flexible fins. This is a fairly heavy rocket with a history of extensive testing. I don't think a fin has ever come off. The fins are attached with original Gorilla glue, and the fillets are somewhat massive. This extremely tacky adhesive is difficult to work with and leave an attractive finish. I have slowly abandoned it on X-3 and other more recent models for Gorilla Superglue. This adhesive can be more easily dispensed in smaller droplets resulting in a smaller fillet. However, I have lost several fins on X-3, so I'm not at all sure I have the best solution for attaching flexible PETG fins.

 

[Dotini]

Reconditioned Magnus X-3, extremely successful flyer, but damages more easily in the joints where I've used superglue.