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Rack Rocket Micro?

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blackjack2564

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Have any of you "usual Suspects" ever built, designed or flown a micro rack rocket?

Kinda sounds like fun. Possibly my next attempt with these new no delay motors.
 

Micromeister

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Have any of you "usual Suspects" ever built, designed or flown a micro rack rocket?

Kinda sounds like fun. Possibly my next attempt with these new no delay motors.
Nope! haven't even been tempted.. since our current booster HAS a delay it didn't seem like a good fit. Waiting for the current .857second avg. delay before igniting upper stage motor is heart stopping enough thank you.

Perhaps down the road, if and when we have a true no delay booster it'll be worth doing.
 

blackjack2564

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I bought several packages of the booster motors. Did not realize that there was a delay.
Sounds like it's just the regular motor with the ejection charge absent.

Me thinks I need to re-think how to use them!
 

MarkII

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I bought several packages of the booster motors. Did not realize that there was a delay.
Sounds like it's just the regular motor with the ejection charge absent.

Me thinks I need to re-think how to use them!
That's correct; Quest removes the ejection charges after they receive them from their German subcontractor. I have not had any experience with trying to stage with Micromaxx II-NEs, but since many of my micros are still going up at a good clip when the ejection fires with the normal motors, it may be possible to build a multi-stager that will work. The rocket will need to be quite light, though, with minimal drag since it will be carrying the weight of an extra stage and an unfired motor. So a rack design might actually have the greatest chance of success.

You could try to give the micro rack rocket extra help in staying vertical for staging by clustering the first booster. You could, for instance, glue two very short and thin standoffs to a Micromaxx II-NE, and then glue another motor into each standoff so that the three were in line. The spacing provided by the standoffs will allow the two outboards to fit around the bottom section of the rocket in between the fins when the central motor is inserted as the first booster in the rack. (You could do the same with three outboards, too, of course.) The enhanced thrust of the clustered first booster could impart enough momentum to keep the rack rocket going vertical prior to igniting the second booster. You might also need to put some cardstock fairings on the tops of the outboards to help cut the drag. It might even be possible to create an attachment that would allow them to fall away as soon as they burned out so that they didn't add to the drag on the rocket during the coast prior to igniting the second booster. With a carefully balanced and lightweight rocket, the speed boost from each subsequent stage could be enough to keep it going vertically during the delays prior to each successive staging so that clustering would not be needed after the first booster. This project sounds like an interesting challenge! :D

Mark K.
 
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Micromeister

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I bought several packages of the booster motors. Did not realize that there was a delay.
Sounds like it's just the regular motor with the ejection charge absent.

Me thinks I need to re-think how to use them!
Jim:
They Stage Great in both nozzle to tale and short gap staged models so far. I've put a few more staged models back in the que for building after seeing my Micro Midget 2-stage and some of the other staged models go.. Wow I wish we had a LONGER delay for the upper stage motor LOL!!!!

They are also proving to be really helpful in drop boosters, some gliders and clustering. I grabbed a gross as soon as they were released and have been playing with them since.

Burn thru produces enough gas to kick very well retained boosters in closed minimum diameter tubes. and I did get some heat bubbling around the forward end on these booster tubes so extra care needs to be taken in the design phase.

I strongly suggest coloring them Red with a wide tip magic marker to help quickly identify these motors from your regular MMX-II motors in the box they look identical;)

MMX-II-NE #5665 Booster motor Stock & WP stor box_02-2009.JPG


MM 362Lp01a_MM T4 MM Midget 2stage on Pad_09-19-09.JPG


MM 390exLp01a_MMX-II-NE_MMX-II on pad_03-03-09.JPG
 

blackjack2564

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How far apart is the recommended gap you've been using successfully? Or just tape them together?
Also are you using a small vent hole/holes?

Yes, right after they came out I remember you mentioning the marking them. Rest assured I did that as soon as I got them! They have been sitting around for awhile, need to come up with something to fly them in other than my saucer.
 
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JAL3

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MarkII

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Think of it as a staged rocket without the stages. Its a bunch of motors sitting on top of each other and which drop off after igniting the next stage

http://www.rocketryforum.com/showthread.php?t=1061

here's another link:

http://rocketdungeon.blogspot.com/2006/01/rack-rockets-mega-staging-and-mega.html
The airframe usually has an open framework along most of its length so that the succession of motors doesn't get snuffed out. Because of that, the rockets actually do sort of resemble storage racks.

Mark K.
 

Micromeister

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Jim:
I've gone as far as 1/2" apart in test models but have not done it more then a time or two at that distance. I like to stay within 1/4" or open butting them without the tape;) as with the Micro Midget and soon to be on the board Beta 2-stage.

At this time I'm not going to suggest trying a Micro Rack Rocket because of the potential of tip off during the Coast phase between burnout and next motor ignition. I've seen this happen a few times with just two motor staged MM models where the sustainer ignites almost horizontally. NOT A GOOD THING with staged models of any size.

Hopefully as the current MMX motor supply shrinks, Quest will make good on their expressed interest in producing a true -0 booster motor in the next run. That'll sure make a big difference in normal staged flights and Rack models would surely not be far out at that point.

MM 362p01_MM T3-T4 Midget 2-Stage_03-30-10.jpg


MM 362uc13b_MMX-II-NE Booster Friction fitted_09-17-09.JPG


MM 362uc13c_Sustainer & Booster 1st Flt Ready_09-17-09.JPG
 

blackjack2564

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Advice well taken.
Just have to wait on the rack attempt.

One thing learned in dealing with micro's........ you must have LOTS of patience!

On to designing my first stager.
 
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