Micromaxx Question

[gladiator1332]

I am interested in makeing a Micromaxx Nova SSTO. I have some plans drawn out for a scale-rocket that is around 6.75 inches tall and 3 inches wide. I want to do a 30 engine micromaxx cluster. I have never launched a Micromaxx before and I really don't even know what the engines look like. Is it possible to do such a large cluster? Can I use normal launch equipment for this rocket? I know Micromaxx come with their own launch controller and pad, but for this rocket I really want to use my own controller since I am getting a 12 volt controller, and I think I'll need every volt of power to get 30 engines off.

 

[jflis]

ouch! man, I've barely mastered *2* engine clusters on MMX motors. Micro may be able to help and I'm sure he'll chime in.

You will certainly need a 12VDC source, but you also need to be concerned about amperage. 30 ignitors will produce quiet the low ohmage, long term (as rocket ignitions go) short across the battery, demanding a goodly current draw. I don't know about others but I wouldn't attempt such a large cluster with anything other than a car battery or a deep-cycle marine battery to start.

not much help, i'm sure, but it's something...

 

[gladiator1332]

I was thinking that the 30 engines would be a bit much. I was also thinking about doing wither a smaller cluster, like three Micromax engines, or just use one larger normal size engines.

 

[powderburner]

30 motors!?!!??
And you haven't even tried one? Wow, I have to admire a dreamer.
I certainly don't want to discourage you from this effort, but maybe you might want to try a smaller-scale version first. Something like four or six or eight 13mm motors.
I am having mixed results with my MMX stuff. I just started a couple weeks ago myself, and am NOT an expert. But I get ignition about 75% of the time I push the button, and that is on just a single-motor rocket. Poor igniter contacts, poor positioning of igniters inside nozzles, low battery power seem to be getting in my way.
A while back, someone built a large scale model of the old Soviet N-1 moon rocket. The model had about a jillion BP motors around the bottom edge. Maybe you can chase down that website and get some tips on coordinating LARGE numbers of igniters?

 

[Micromeister]

OUCH is Right Jim:
First, the Micromax motor is about 1/4" in dia. x 1inch long, the Nozzle opening is just a tad larger then 1/16" average about .061" in dia.
My personal best "mrcluster" wise cluster has been 8 micro's using 32gage nichrome and my own AP based pyrogen. Bare Nichrome best to date has been 4 motors. cluster consistency has only recently been improving with the introduction of 34gage nichrome. I have no real practical experience with Mega clusters over 12 standard D12 motors and only 10 motors in the 13mm and 18mm BP motors sizes. I've "Seen" folks attempt mega clusters with the "Flashpan method" I can attest to the fact this method reallly "Cooks" the bottom of the model, while not necessarily igniting all the motors.
Using the 34gage nichorme/pyrogen igniters and a 40amp relay at the launcher with a very good HI amp/hr battery, 60 amp/hr or higher your chances of all the motors going are still very slim. Actually, I'd really like to know a little more info. Can you be specific as to the expected lift-off wight of this model? I am familiar with your prototype, as a Scale modeler, Micro-maxx and cluster nut, I'd be inclined to do a 3 or 4 motor 18mm culster with a ring of micros around the outside where their missing thrust will not upset the applecart much. Even then this would make a fairly simple, reliable cluster into a major heads up flight. I have to ask, Why would you want to spend the time building a Scale model, finishing it and then destroy it with an unproven, very unrealiable motor combination??? Oh.. one more thing 30 MM-II"s will give you about 9.3 n/sec or 2.09 lbs for about .5 seconds. A single motor will give you a much better chance of a successful flight. If you were thinking of entering this in a scale competition for flight and difficulty points, you might overcome the total distuction of the bottom of the model..but I'm not sure. OBTW I'd rethink the styrofoam ball idea also. Maybe use the foam ball as a mold for a fibreglass hemisphere..the foam will melt away to nothing if only a few motor's actually burn.
Hope this helps a little, Keep us posted if you actually attempt this. Some of us Micro-Maxxer's will be trying various big cluster tests this fall but even these were only in the 8 to 20 motors range that will fit in a BT-60 size body.. but these are not scale models, their 3F&NC test beds, we don't care it the bottoms get singed

 

[Micromeister]

PowderBurner:
if you want to end your problems with the Quest silo launcher base when you exhaust your next 9V battery, take it appart, clip off the leads under the cap and solder it to about 5 feet of 2 conductior lamp cord the small 20 or 22 gage stuff is fine. add a couple alligator clips, warp the outside of the solders cilp with 1/2" masking tape to make a mold, fill with epoxy, remove the masking tape.. your new power lead is Done.. connect to the 9v cap in the contoller and close the door..Oh ya may need to file a small open in the door edge for the wire to exit the controller. connect directly to any 12volt battery.. your good to go. No more low voltage problems.
Trim the excess paper for both sides of the stock igniters before pushing it into the base slot... make removal a LOT easier.
after about 10 flights clean the contacts down inside the slot with alcohol. that will take care of your contact problem.

OR connect the Quest stock igniter to you standard every day launcher clip by bending the heavy 30gage wires at the bottom of the igniter about 1/2 a turn.

either way once your back to 12v systems your ignition problem will disappear.
Hope these tips help...heres a pic of the power cord conversion.

 

[powderburner]

Thanks for the tip, John---
I saw this 12V plug-in on another thread you posted to recently, but have not had time yet to get one of these contraptions built. I am looking forward to using 12V power; I have a spare vehicle battery that I keep anyway (for powering our camper) and that thing certainly will have all the amps I'll ever need.
Thanks again!

 

[Micromeister]

Powderburner:
You may want to convert the silo base to use your own bare nichrome igniters also I'm not sure I can get the whole pictorial conversion reduced far enough to post it here. I'll try if not, it's listed in the files secton of the MicroMaxRockets yahoo group. Art Applewhite also has an easy plain launcher that uses two cloths pins.
Yeap your vehicle battery will do nicely, a small gel-cell does a nice job also.

well it's pretty small 72dpi I doubt anyone will be able to read the text, maybe the pics will help

 

[gladiator1332]

Yeha iK now I was dreaming when I thought of a 30 engine cluster. Hey even NASA is guilty of over-dreaming....common 500 shuttle launches by 1990?

I have only seen a 30 engine cluster done once, I saw some pictures online of a 30 engine cluster for an N-1.

I'm most likely going with a D-Engine for this one...but I hope to get into Micromax soon.

 

[powderburner]

And here I was getting all excited to see how you made this thing work.

 

[rstaff3]

Anyone know if this project flew at LDRS as planned? results?

https://www.ldrs22.org/images/specproj/maxied/maxied.html

 

[Mike]

- I think that basically sums it up

 

[Micromeister]

Only if you like burning up the bottom of your models Mike.

If you have a LEUP, and If you have loose BP, flash pan ignition might be ok. But for all us non-LEUP, never gonna get a LEUP folks, Loose BP and the flash-pan method are just not an option. I'd rather find safer ways to Reliably ignite large motor clusters. The research goes on...