Horizontal Spin Recovery - with Magnus Effect?
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Thanks for your encouragement! Magnus X-2 is almost finished, lacking only some small details and finish. It should easily fly by next week, weather permitting. X-3 is off the drawing board and parts are in work. It should make your socks roll up and down. X-4 is on the drawing board, and if I can execute it, I fully expect it will start a riot.It‘s over 15 yrs probably closer to 20....only flew it 3 times....I use a lot of clear coat so it’s easy to clean and touch up. Can’t wait to see how Dotini’s roc flys and comes down. Very interesting concept.
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That's always tempting fate...
Absolutely!
#1. Around this time of the year the grass and fields are almost always wet and muddy. Paint will help protect the paper and balsa to a degree.
#2. We are dealing with thin rockets and a rocketeer with slowly failing eyesight. A contrasting pattern of black and white helps him follow the rocket and to understand its antics at apogee.
#3. I'm new at the forum, and would strive to present my work in the finest traditions of model rocketry, to soothe the souls of Vern Estes and G. Harry Stine, and to set a good example.
#4. I have no fear of taboos or of setbacks. I follow the 6 P's of another of my heroes, Roger Penske, who said: "Proper Preparation Prevents Piss Poor Performance."
icyclops
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Ha Ha...sounds good....I just hate redoing things so I find that i just put on a base coat/primer before test flight, it gives me a little more time to ponder the paint scheme and to touch up the primer if anything goes south....but “going for it” is another way no doubt. Can”t wait to hear how it comes down.
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Back in my misspent youth, when I wasn't otherwise occupied with work, mountaineering or racing cars, I made rockets with D, E and F motors. Many of these models never survived their first flight, mostly due to getting lost but some having the fins explode off the body. In retrospect, I can see that these paint jobs were wasted, although their loss was felt more poignantly.
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Probability of misadventure on Maiden flight is usually roughly proportional to the amount of time finishing the rocket.
icyclops
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I have found that to be very true.....
Okay, I can see what's happening. The forum is ganging up on me in my own thread to influence me to launch my rockets without finish. So I will capitulate to some degree and leave my model entirely in primer. But I insist on using both black and white - no gloss, no colors - in order to allow the old man with poor eyesights some relief in watching his rocket's antics.
I hope I'm wrong, and please correct me if I'm wrong. But I'm getting the vibe that to launch a rocket that is finished is statistically correlated to misadventure on first launch compared to a rocket that is unfinished. I'd like to see the evidence. To me, this sounds more like superstition and taboo than science and engineering. Now, there is - or was - a place in rocketry for superstition, taboo and the occult. Jack Parsons and Wernher von Braun may have exemplified that.
My schedule for launching both X-2 and X-3 is taking a setback due to a damned rattle can problem on X-1 and time-consuming complexity in the case of X-3. My time for rocketry is also being usurped by duties at my fishing cabin and doubling up on fencing lessons starting next week.
The last few weeks have been a heady trip, but now it's time I slowed down and attended to other aspects of life as well. Be well.
My schedule for launching both X-2 and X-3 is taking a setback due to a damned rattle can problem on X-1 and time-consuming complexity in the case of X-3. My time for rocketry is also being usurped by duties at my fishing cabin and doubling up on fencing lessons starting next week.
The last few weeks have been a heady trip, but now it's time I slowed down and attended to other aspects of life as well. Be well.
Science shows that the best way to launch a new rocket is to perform a ritual sacrifice to the rocket gods, usually in the form of a B6-4 or whatever motor the manufacturer recommends for the first launch. Waiting for a low wind day also helps...
Someday, science will develop a vaccine against losing new rockets.
Someday, science will develop a vaccine against losing new rockets.
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Just because it’s voodoo doesn’t make it wrong..... there are forces at work here in model rocketry that don’t give a hoot about physics. You think the “Magnus Force” is weird, brother wait until you challenge the “Murphy Force.”
some of my prototypes get a coating of fluorescent orange or pink. No primer. That’s just so I can FIND them.
Back in the mid-eighties I bought a 4 bedroom home in the Ballard neighborhood of Seattle. I was obliged to take in renters for a few years in order to make ends meet. One, whom I'd got to know, was from Hawaii with the surname Ikeda, employed as a chemist. One day I asked him about the Menehune. He changed color, went stolid and refused to talk about it.
Question: What is the statistical probability that the Estes B6-4 will perform very closely to its specifications?
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I think the QC is supposed to be +/-10%
That's a slightly disappointing figure, but I guess it is what it is, and applies to ejection charge as well, I assume. I'm thinking about the sheer violence of the sideway ejection charge on the fixed-cone experimental horizontal spin rocket (X-1) I've flown. Possibly it played a role in damaging the lower fuselage. Very likely it is no sure thing in assuring the rocket takes a tail first descent.
What effect, good or bad, do you think the addition of a 2nd port would be? I'm thinking of testing a 2nd port, not side by side, but sited on the same half of the rocket and maybe 0.5" lower.
My X-2 is also being prepared with a 2nd detachable upper section, this one sporting an ejecting nose cone with streamer, in order to test that particular configuration for comparison in its behavior at apogee and descent.
By omission of spiral filler and other shortcuts, an active morning in the paint booth has brought X-2 back on schedule for a launch very soon.
Question: as motors progress in impulse going up the classes A, B, C, D and so on, does the ejection charge impulse stay at a fixed value, or does it increase proportionately from type to type, or just what?
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icyclops
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Sure, just ask all those engineers and scientist of early missile design, roc design, about their success rate.....better yet, ask ELON....It’s not voodoo, it’s probability. Has this thread become a discussion on wether to prime and launch or paint like you want to and launch. I was under the impression that the main thing was to see if this effect works in recovery.....guess not.
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Respectfully disagree.Sure, just ask all those engineers and scientist of early missile design, roc design, about their success rate.....better yet, ask ELON....It’s not voodoo, it’s probability. Has this thread become a discussion on wether to prime and launch or paint like you want to and launch. I was under the impression that the main thing was to see if this effect works in recovery.....guess not.
Musk’s Falcon 1 finish wasn’t exactly Michealangelo, but it was painted with a logo
Good reasons to paint model rocket prototypes include visibility (I launched an unpainted FlutterBye in fall. Unpainted body tubes and balsa look a lot like autumn leaves. I found the upper half with the nose cone. The thing only went up about 200 feet), aerodynamics (smooth light paint jobs can fly higher), and water resistance (wet grass warps bare balsa in a hurry.). Plus some designers may look at a paint scheme like an autograph on their designs. So while I choose to fly (my rockets) naked, it’s very much an individual choice.
in the case of horizontal spin, Dotini is doing something generally not done before (at least according to Tim Van Milligan’s book.). Not that Horizontal Spin is done much at all (to my admittedly limited knowledge,@Dotini and I are the only ones at least in recent years to post on this technique.). But per Tim’s book and in my flights, usually the nose is blown and recovered separately. @Dotini is doing it with nose cone intact, he’s “borrowing” or “adapting” a trick from Back Sliders to interrupt the initial streamlined forward trajectory. Presence or absence of paint may make a bigger difference in these rockets than most, as it will definitely move CG well forward (since his are classically long skinny rockets). Likely there is a point where the forward CG overwhelms the effect of spin and the rocket “refuses” to turn horizontal. Also the added inertia of the painted tube may make it more likely to flex.
back to theory and practice, to stay on topic.
what if we placed two ports, equally spaced forward and aft of the CG, pointing in opposite directions? I don’t think this would ELIMINATE bending stress, but it might distribute it more evenly across the airframe (or conversely make it even worse, focusing it right AT the CG.....course you could but a coupler there, but it’s gonna cost you some mass and may just focus the bending force at the fore and aft marines of the coupler....)
another unknown is just how far forward does the port have to be? Could you put a port in the rear, just forward of the engine block, and blow the tail of the rocket sideways enough? Would that cause more or less lateral bending stress?
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Lacking only launch lugs and port(s), Magnus X-2 is ready for testing.
Magnus X-2, posed with ejectable nose cone, and alternate upper section with fixed nose cone (yellow).
Length, currently 63". Breaks down into 4 sections for transport.
Weight, 3.43 oz., not including tape, streamer or motor.
Magnus X-2, posed with ejectable nose cone, and alternate upper section with fixed nose cone (yellow).
Length, currently 63". Breaks down into 4 sections for transport.
Weight, 3.43 oz., not including tape, streamer or motor.
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She’s a beaut!
is this 18mm?
hmmm, you are at 97 grams without motor. Recommended max lift off for B6-2 is 127 grams, so that’s do-able.
https://estesrockets.com/wp-content/uploads/Educator/Estes_Engine_Chart.pdf
you are going to be over the limit for B6-4 and C6-3 and C6-5 (you are in good company, the Estes RTF new Saturn V is waaaay over the limit, most fliers seem to get away with it), hope you have a relatively windless day for launch.
so you gonna go one hole or two? And if one, where to put it?
you may need two lugs, a small forward lug, mainly to keep it from pushing over on the pad and ripping off the rear lug (wind on the long forward body tube section is going to cause significant stress if the torque point is near the tail), and a longer tail lug which will keep the rocket stable on the rod during actual lift off. Going with CG position of a single lug is problematic, as it may be so far forward it will only be 18” from the tip of the rod (EFFECTIVE rod length is the length of rod forward to EITHER the forward lug [two small lugs] or the forward end of the rear lug [if you use a relatively long rear lug, it can function independent of the forward lug.). A longer rod helps but risks rod whip.
alignment of two widely spaced lugs may not be as problematic as you think. Since this breaks down into sections, as long as both lugs are straight (and especially if the forward lug is short and more forgiving), put the rocket together on the rod, line up both lugs perfectly, and put tick marks on the adjacent body tube sections. Then just line up the tick marks every time your set up the full stack and Bob’s Your Uncle (blame @mbeels for me now having this phrase stuck in my head!)
assuming as I suspect a resound success for your first flight, if the stars are aligned, the winds are light, and you have few or preferably zero spectators except those you bring specifically to watch the launch, AND if you feel particularly brave, you may try a second launch with one section removed (I.e,, shorter.). The question is, can adding horizontal spin effect substitute for SuperRoc length when horizontal spin is done WITHOUT blowing those nose cone? I will probably find out tomorrow, wind permitting, with SQUIRT!
tip. If your using segmental construction and breaking apart your rocket using couplers, put a wrap of clear cellophane tape around each tube edge where you are going to tape them together. Wrap both wraps in the SAME direction with the tubes CONNECTED, and preferably in the OPPOSITE direction of the way you PERSONALLY usually wrap tape. This provides a BASE for the tape wrap which you will put on and take off when you build and unbuild the rocket in the field, respectively. It keeps the new tape from peeling up the paint or even worse the body tube when your remove it. The reason to go in the OPPOSITE direction from the field tape layer is that sometimes the field tape will try to peel off the permanent tape with it if both are going the same way.
I am sure you can figure out how I learned this!
good luck!
And I've got Chim-Chim-Chimeny stuck in mine!
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Turnabout is fair play!
I accidentally made my model too long. so I have trimmed it back to 50.5" and 3.1 oz, less motor and streamers, lugs and tape. Now I can find the CG and put the lugs in place.
I'm hoping it will launch on any of B4-2, B6-2, C5-3 or C6-3.
With my next rocket, X-3, I will add the option of C11-3. Oh my!
I'm hoping it will launch on any of B4-2, B6-2, C5-3 or C6-3.
With my next rocket, X-3, I will add the option of C11-3. Oh my!
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If you elect to use two ports, I'd made the AFT one much smaller than the forward port as the ejection charge pressure in the aft part of the tube will be much higher than in the forward part of the body tube. Hopefully this will alleviate the uneven torquing of the body tube that may be causing the damage.
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Good thought. I’m still trying to get my head around the physics of whether two opposing ports at opposite ends cause MORE or LESS localized bending stress than a single port at the end with the lowest mass! Where is @prfesser when you need him? Part of the problem is, “in a free flying or falling rocket, when you push on one end, where exactly is the fulcrum??”
IMHO that would be the CG.
I'm thinking about two ports, on a diagonal, 3/8" apart, at the top. This will release the ejection gases slightly more slowly and less violently, fan the gases out in a wider arc, and still act to push the front preferably horizontal.
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