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  #1  
Old 08-20-2008, 11:38 PM
bringrose bringrose is offline
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Question 3 Stage Rocket

Hey,

I'm currently designing a model rocket and would like to make it 3 stages and have a few questions and concerns. First is it even possible to do 3 stages and if so is it anything like 2 stages? Second when using this much power should I be considering the weight of the rocket? And lastly do the first 2 stages need to break away or can they just fall out of the tube?

Any help is much appreciated!

Ben
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  #2  
Old 08-21-2008, 12:09 AM
stefanj stefanj is offline
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Ben:

Three stage rockets are nowhere near as common as two-stagers, but people have built them and there have been commercial three-stagers.

I strongly suggest looking at existing designs, and to read the Estes technical report on staging.

This PDF ("The Classic Collection") contains the mulitstaging technical report:

http://www.esteseducator.com/Pdf_files/1976clas.pdf

This page has links to scanned in Estes plans. Look up the Farside and the Comanche-3:

http://www.dars.org/jimz/estes.htm
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  #3  
Old 08-21-2008, 12:17 AM
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Mark II Mark II is offline
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Quote:
Originally Posted by bringrose
Hey,

I'm currently designing a model rocket and would like to make it 3 stages and have a few questions and concerns. First is it even possible to do 3 stages and if so is it anything like 2 stages? Second when using this much power should I be considering the weight of the rocket? And lastly do the first 2 stages need to break away or can they just fall out of the tube?

Any help is much appreciated!

Ben

I'm sure that other forum members will have much more to say on this subject, but the quick answers to your first (2-part) question is yes and yes. Both Estes (the Comanche-3) and FlisKits (the Nomad) offer 3-stage rocket kits. The answer to your second question about the weight of the rocket is the biggest issue right now with designing and building 3-stage rockets that fly on black powder motors, but this wasn't always the case. You have to be very careful in designing and constructing your 3-stager so that the low- to medium-thrust black powder motor (those are the only kind that are being made right now) in the first stage has enough power to get the entire stack going at a stable speed.

Your third question asks whether any design requires drop-staging or if it is possible to employ CHAD-staging. I don't know of anyone who has ever done CHAD-staging of 3 motors in a single motor tube; I would think that the exhaust plume of the second, and especially the third, motors would incinerate the motor tube as they fired. Drop-staging, in which parts of the rocket (not just spent motors) are dropped as each stage fires, is the only method that I know of for a 3-staged rocket, although CHAD-staging is sometimes done with 2-stagers.

In the 1960's and early 1970's, there was once another method of direct staging of black powder motors that was tried, which also had all of the motors contained in a single motor tube, but it was abandoned because the method was highly prone to CATO's. That's all that I'm going to say about it, too.

Mark \\.
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Old 08-21-2008, 12:54 AM
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Mark II Mark II is offline
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I neglected to mention another 3-staged rocket, the Cyber III. This was not a kit but rather was a design and plan published by Semroc Astronautics back in May, 1970 (first page. second page). John Lee (JAL3) has an ongoing build thread for his version of this rocket on TRF, and I have also recently built this rocket. My RockSim 8 simulation demonstrates that this design is indeed flight-worthy on currently available motors, but I have not actually flown mine yet.

Mark \\.
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  #5  
Old 08-21-2008, 07:07 AM
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STRMan STRMan is offline
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Quote:
That's all that I'm going to say about it, too.


"Those who fail to learn from history are doomed to repeat it" Sir Winston Churchill

Please elaborate my friend. Inquiring minds (well, at least one ) want to know.
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Old 08-21-2008, 11:29 AM
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ghrocketman ghrocketman is offline
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Don't forget the Centuri Arrow-300 and the Centuri T-Bird.
Both are 3-stage designs that were commercial kits.
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Old 08-21-2008, 11:44 AM
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Quote:
Originally Posted by bringrose
Hey,

I'm currently designing a model rocket and would like to make it 3 stages and have a few questions and concerns. First is it even possible to do 3 stages and if so is it anything like 2 stages? Second when using this much power should I be considering the weight of the rocket? And lastly do the first 2 stages need to break away or can they just fall out of the tube?
Ben,

It sounds like you haven't done any staging yet. I suggest you get a basic 2-stager and get some experience with that first. Much of what you learn there will apply to 3-stagers.

I do mostly scratch-building, so I'm at a loss to recommend a kit; otherwise I would give you a link. Sorry.

Doug

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  #8  
Old 08-21-2008, 11:48 AM
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Quote:
Originally Posted by bringrose
Hey,

I'm currently designing a model rocket and would like to make it 3 stages and have a few questions and concerns. First is it even possible to do 3 stages and if so is it anything like 2 stages? Second when using this much power should I be considering the weight of the rocket? And lastly do the first 2 stages need to break away or can they just fall out of the tube?

Any help is much appreciated!

Ben


Ben,

Welcome to our asylum!

Have you had a chance to pick up a copy of Stine's Handbook? The questions you ask are (almost) right off the pages of that book.

My first recommendation is to order a copy and read it completely, then keep it at your design desk for reference.

The second recommendation is to download the DEMO of RockSim and just play around with it, adding and removing basic components to a simulated version of your design until you achieve what looks good and flies acceptably. The Handbook gives you the background information, while RockSim lets you see theory become practice. It will reinforce what you learn from the book.
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  #9  
Old 08-21-2008, 11:49 AM
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Shreadvector Shreadvector is offline
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I think I have a few Super Samuri kits left. I have not bagged any new kits in a while.

Read all about multi-staging in the Estes Classic Collection:

http://www.esteseducator.com/Pdf_files/1976clas.pdf

If anyone is seriously interested, e-mail me.

http://www.geocities.com/fredeshecter/prdctinf.pdf
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  #10  
Old 08-21-2008, 12:17 PM
Green Dragon Green Dragon is offline
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Quote:
Originally Posted by Mark II
Your third question asks whether any design requires drop-staging or if it is possible to employ CHAD-staging. I don't know of anyone who has ever done CHAD-staging of 3 motors in a single motor tube; I would think that the exhaust plume of the second, and especially the third, motors would incinerate the motor tube as they fired. Drop-staging, in which parts of the rocket (not just spent motors) are dropped as each stage fires, is the only method that I know of for a 3-staged rocket, although CHAD-staging is sometimes done with 2-stagers.
\\.


OK, going to answer this two ways, lol ...

1) as for chad staging - this being where you just hang the booster motor out inthe airstream behind a single stage rocket - done this many times 2 stage. including drop staged clusters ( ie: 3 x D12's glued together in parrallel, dropped off a singe D12 upper stage
However. I can say firsthand that the Estes Maxi Alpha 3 can be tripple stage chad staged, but not reccomended.. mine flew fine 3x D12's hanging out in the wind, but if any wind might weathercock, do to the slow liftoff wieght on a D12, if ,say an FSI D20 or similar was available for th elowest stage, go for it

2) there is a concept called a ''rack rocket' wherein motors just kick back out of a slotted / vented tube - I have flown 5 stage D12's in an Achilles rack rocket design ( see the Oct or Dec 1985 Tripolitan for plans )
Much fun, need to build another one

but yeah, get some experience wiht 2 stagers, and start with plans or a KIT before tackiling anyhting more extreme .

~ AL
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