#11
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Parallel Stages
Hi SoopirV. www.vernarockets.com is where I saw the design and had to have it! As far as my problems, u r correct. Because that outside pod didn't ignite, it grabbed rod. To prevent this use 12v and quest new Q2 igniters. They r much better than estes solar igniters. Also, a sturdy "clip whip" is the only way to go. Don't even bother trying to "twist igniters " together. FYI, Spiff was made by gluing 3 Bullpup12 D's together. Even @ a good price, cost nearly $50 to build! That said, I'm even more enthusiastic about build clusters. I have a rebuild in my shop now, I have yet to start. Rocket was my first design from 25 years ago! Now they have 13mm motors so going to try 5 engine cluster. Three 18MM and two 13mm motors. Glenn NAR 89197
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#12
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Joe, The only thing I have from you that I still need to get online are the Black Knight fin patterns. If you have other CMR stuff, please send it to me. Thanks.
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Scott D. Hansen Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe! Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies! Ye Olde Rocket Forum WOOSH NAR Section #558 |
#13
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Like I said, I thought I sent them to you. My brain is so overloaded these days its a wonder I can amke it to work safely...... I'll dig up the Marcus instructions when I get home tonight. |
#14
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I thought clip whips are frowned upon in general; makes for more of chance of a misfire of one or more of the motors in a cluster. So far, I've had great results not using a whip (at least on my motors! Now my kids.... ). Allen |
#15
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Parallel Staged Rockets
Clip Whips r quite the opposite. More reliable than any other method. Glenn NAR 89197
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#16
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I finished (building) a Force 5 a couple of weeks back. I was really happy with how it turned out. I made a newbie mistake and didn't wash my nose cone prior to painting and my paint did not stick when I later masked it for an anti-glare panel so large sections pulled off....
So I tossed it into the stripping tank and I'll do it over. I'll post some shots when I finish it all up. |
#17
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Super secret Plastic finishing hint: Go to the auto parts store, pick up a rattel can of "adheasion promoter" . FIRST test it on the base of the nose cone where if you have an adverse reaction it won't show up later. But I have not had a problem with Rocket plastics yet. What this does is make the paint more likely to stick to plastic. In the real worls we use it on plastic bumpers to get paint to stick. . |
#18
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I've had good results using Krylon's 'Fusion' spray paint made for plastics.
Allen |
#19
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Fusion paints. Heard of them, but have not tried them yet personally. Sounds like a good (less expensive) idea!
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#20
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There is a difference between "parallel staging" and a "cluster". A "cluster" is a group of engines which are all lit at the same time (which may burn out at different times) but which all remain attached to the rocket for recovery. A three engine cluster can either be arranged in a triangle pattern or as a straight line. What HotRod Lincoln is describing is a cluster. Garmtn's picture of his Spaceman Spiff rocket is a good example of what you are trying to avoid with clusters. It appears only two of the engines lit, forcing the rocket over enough that it bound the launch rod, and apparently pulled it up out of the launch rack. That rocket is leaving the launch rack at 45 degrees carrying the launch rod with it. Garmtn's assessment that the flight went well is somewhat more generous than mine. "Parallel staging" is when shorter burning additional booster motors are placed around a longer burning central core motor(s), and the outside motors drop away after they are done burning, reducing the drag of the rocket. The key design consideration with these is that they need to be affixed in such a way that if one or more of them don't light they are still carried along with the rocket (not left behind on the pad) and that if the central core motor doesn't light, the side motors don't just launch themselves up along side the core rocket, leaving the rocket behind. Unfortunately, the examples given so far in this thread don't meet those requirements. A booster motor that simply drag separates after burnout is one that will be left behind on the pad if it doesn't light. That will cause your rocket to do what Garmtn's did, tilt over and fly off in a direction you don't want. Additionally, the motors left on the pad may delay light, causing their own problem. The best system I've seen for parallel staging was sold (no longer available) by Ray Dunakin of Hako Ballistics. The attached photo comes from Ray's site. At the aft end a piece with a horizontal rod is glued to the central core (sustainer) rocket. A matching piece with a beveled out slot (to sit on the horizontal bar) is attached to the parallel staged booster engine. This arrangement ensures that if the core lights, but the side booster doesn't, the side booster will still be carried along with the rocket. At the top end, a piece with a forward facing hook is glued to the sustainer rocket. A slot is cut in the tube of the parallel staged booster tube that matches the slot. The intact part of the tube at the bottom of the slot rests against the underside of the hook on the sustainer. The hook extends into the side tube far enough that when a nosecone is placed into the side tube, it slips over the hook, locking it in place. This ensures that if the side motors light, but the sustainer doesn't, that the side motors will remain attached to the sustainer. They only fall away after their ejection charges blow off their nosecones allowing them to fall away from the sustainer. This is a very clever, reliable, and safe system for parallel staging. Unfortunately Ray no longer makes or sells the parts. There was also a company called Advanced Rocketry Corporation (ARC) out of Arizona that sold a couple of parallel staged kits (EMRR review here ) which used a different, but also reliable, arrangement, but it doesn't appear they are still in business. The kits do come up on eBay from time to time, though. Clusters are lots of fun, as are parallel staged rockets, but the parallel staging is a pretty complex arrangement to pull off safely. Hope this lengthy explanation helps, Gus |
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