3mm Rocket Engine?

[Rocketbuilder]

Hello,

I was wondering if it is possible to make a 3mm diameter rocket engine. What could I possibly want that for? A 1/480th Mercury Redstone. So, is it possible? and if so, what would be the best method to go about making such a thing?

At least if something went wrong with such a small engine, it wouldn't be much of a disaster.

 

[Aksrockets]

You might as well just use a firework fuse, as they can be quite propulsive. 3mm engines would be very hard to make. Molding the nozzle would be darn near impossible, plus the delay charge and ejection charge would be hell.

It would be cool though.

Alex

 

[bobkrech]

Don't bother. That's too small. Try this with a Micro-Max.

Got to Delta 7 Studios and download the 1/96th scale Mercury 7 paper rocket and instructions. Assemble it printed out 1:1.

Print at out at 20% to get 1/480 scale. Put it together if you can so see how small it is. This is rediculous.

A 6mm diameter to match the micro-max is 1/288 scale which is more realistic. Print out the rocket at 34% to fit the micro-max motor. You will find that amazingly challenging.

Bob

 

[Rocketbuilder]

Print at out at 20% to get 1/480 scale. Put it together if you can so see how small it is. This is rediculous.

I already have, using nothing but kitchen shears and my fingers. Of course it's ridiculous; that's the point!
When I built it I really didn't expect to ever fly it, I just wanted to make a Mercury Redstone to go along with my 1/480th Saturn 1B and Saturn V. But now that I've built it I can't resist trying to fly it.

I probably will use one of the fuses that is basically a paper tube of BP. But I think I know how to mold a nozzle that small...

 

[billspad]

You might as well just use a firework fuse, as they can be quite propulsive. 3mm engines would be very hard to make. Molding the nozzle would be darn near impossible, plus the delay charge and ejection charge would be hell.

It would be cool though.

Alex

I've seen this done with thermalite and a small brass tube as a casing and no nozzle. Obviously there was no delay or ejection charge but the rocket it was in was tiny.

 

[Micromeister]

It'd be easier to build a forced air (Stomp rocket) type launcher for such a small, feather light model.

I have a 1:200th Merc-Redstone PMC that flys on the old standard MMX-I motor. First time I launched it...it was GONE for almost two months until one of the guys happened to find it our retreiving his model. It has a 8" white teflon tape streamer recovery but NOONE heard or saw the deployment.

I'd be very surprised if you saw or recovered your 1:480 model even using a 16oz size air powered launcher with no recovery system. These tiny Paper models can get 60 -100feet with ease.

 

[JPVegh]

Anything is possible.:wink:

 

[New Ocean]

https://highpowerrocketry.blogspot.com/2008/06/match-rocket.html

 

[Rocketbuilder]

Bill:
That's very similar to what I'll probably do, except maybe with the addition of a small flash powder charge to separate the two halves of the rocket. (It breaks apart in the middle and the halves are held together by a piece of string.)

Micromeister:
If practicality was the goal, that would obviously be the way to go. But now I'm determined to put a "true" rocket motor in this thing, even if I lose it, which is pretty much inevitable in the grass at my launch site.

JPVegh:
I agree!

 

[kpklein]

I have made 1/8" ID blackpowder motors, or do you mean 3mm OD ?

 

[Rocketbuilder]

1/8" OD. How would you make your own BP motors? Is there a casting process similar to KNO3 propellant?

Next time I am out I will try to pick up some 1/8" brass tubing at my LHS.

 

[Wingarcher]

BP motors are made from pressed or rammed black powder, mixed to a variety of "hotness" depending on the design of the motor.

They can be cored or not, if they are cored the increments are rammed or pressed around a spindle that creates the (tapered) core. A clay bulkhead at the front keeps everything under control at the end of the burn.

You can make end burners, but will need to experiment with the BP mix to get it hot enough to actually do something, especially since you may not be able to get a nozzle pressed into such a tiny tube.

You may want to look into "spollets". They're a type of fireworks fusing used on large aerial shells. They look like they might be propulsive, at the least they're close to the right size. Fireworks rockets tend to be a hair bigger with the 1/8" ID being a small novelty type item. 1/2" ID cored makes a heck of a nice rocket, BTW. The flame is enormous at night. 3' long?

N

 

[bobkrech]

Folks

Making BP motors not something we advocate, and you need a BATFE license to make them.

As a matter of TRF policy, we do not get into the details of making motors in this public forum and this thread is beginning to go over the line.

Qualified members can continue this discussion in the research forum.

Thanks.

Bob Krech, Moderator

 

[kpklein]

Just to be clear, I have no intentions of giving instructions or encouraging any forum members on how to build a motor, BP or Composite, I assume anyone who does have experiance making experimental motors or fireworks will be informed enugh to use thier own good jugement.

I have braught my BP motors to launches and some object to the use of fuses rather than a proper launch controll system.

 

[cavecentral]

I have braught my BP motors to launches and some object to the use of fuses rather than a proper launch controll system.

Launching via fuse is a safety code violation. Most clubs don't allow it. Any club that observes the safety code shouldn't allow this.

NAR does not support research motors of any form. Tripoli does, but not BP motors. I don't think the interest level is high enough, and high power ones seem scary dangerous to make. APCP is so much easier / safer.

I would imagine that any fireworks club would support home made BP motors since that is what most of their rocket motors are.

 

[bobkrech]

Actually you can use an remotely activated electrically initiated fuse to ignite a motor.

The Feds say making BP motors and fireworks requires a BATFE explosives permit. Home made BP motors and fireworks are not allowed at NAR or TRA launches so we believe either topic is appropriate for this public forum.

Bob

 

[cavecentral]

Actually you can use an remotely activated electrically initiated fuse to ignite a motor.

True. Just the ol' bic lighter method is frowned upon.

I think ignition has to be pretty quick though. Hitting the button, then waiting 10 seconds for the fuse to burn is a bad idea. It should be fairly immediate. If a long fuse is burning and an airplane flies overhead, there is no way to wait or cancel the launch.

 

[Rocketbuilder]

I do not intend to make my own BP motors; I was simply curious, as I did not know how they were made. I am aware that giving specific instructions on making homemade motors is not permitted on TRF (yes, I actually did read the rules when I joined), and I do not intend to get them here. If I do seek such instructions, I will do so on other websites that support homemade motors. And if I ever actually do make my own motors, which is unlikely, I will do it legally, and I will observe all necessary (and some extra, unnecessary but still a good idea) safety precautions.

Also keep in mind that statistically, 3mm rocket motors of any type are far less dangerous than stairs. Not to say one shouldn't be careful with explosives, I just couldn't resist pointing that out.

I hope that allays any concerns any of you may have had.

 

[Blakkzakk]

The manufacture of 3mm rocket motors would require special and unique workers.

 

[Reinhard]

This is the smallest rocket I'm aware of. Sorry, the text is in German, but the numbers should be self explanatory.
https://astronomie.hausdernatur.at/images_aktiv/guinnessrekord.jpg

The motor was based on a tiny firecracker, slightly modified so it can vent safely without bursting. I don't remember the actual height reached, but it could be launched indoors without problem.

Reinhard

 

[spacecadet]

Folks


Qualified members can continue this discussion in the research forum.

You do qualify, being resident in the US (I believe passports are not checked), which I understand is the only criterion.
I as you can see do not.