7 replies to this topic

[maxman]

I'm trying to replicate a commercial motor. I have carefully examined a motor from a Midas gold medal rocket suplied by Lidl. I just cant seem to get the same power from mine. The fuel burns slower than than straight meal. I would say at a guess something like 80/20 meal / charcoal, yet the core dimensions are so much smaller than that used for standard BP rockets. I have some video of a few grams of the fuel burning. It seems to burn with a slightly pinkish tinge (to my eye) unlike when I burn meal or BP fuel.

It it likely that it isnt BP at all?


The dimensions of the motor are:

Midas Gold Medal

TOTAL DEVICE WEIGHT 110G
TOTAL MOTOR 29.1g
STICK 17.2g 29" X 6MM SQ
MOTOR 85MM LONG
16MM ID
20MM OD
CLAY PLUG 2OMM
5MM THROAT
CORE 20MM INTO GRAIN 40MM IN THROAT (INC CLAY)


These rockets have very little tail yet seem to have bits in the black fuel that resembles titanium?
When these motors are fired on there own using only a stick the go so fast Its almost impossible to video.However when the full weight of payload is added they are perfect and reach a good altitude.

I then made a motor:

ID 3/4"
OD 1"
LENGTH 3.5"
20MM CLAY PLUG
CORE 15MM INTO GRAIN (35MM INC PLUG)
6MM THROAT
STRAIGHT MEAL 5%TI

And lifted the stick and payload of the rocket whos motor I had examined. The results were no where near as good yet got it to a safe enough altitude.

Im just thinking is it something other than BP????

Can send vids and pictures if someone wants to host them.

[Dj Killerboss]

No it's bp. I found 1 year ago the correct formula for it but didn't know the pape anymore. It burns slow but with the small Nozzle and the Visco going half into the motor and burning fast the rocket motor has power.
They are pressed with very high pressures so your motor was weaker than the bought one.
Rocket propellants didn't need to burn fast, if the rocket motor is optimized for it.
I have tried much sorts of propellants but the RP from VK2ZAY's page is powerful enough and made a nice tail.

greez

Edited by Dj Killerboss, 04 January 2007 - 05:19 PM.

[The Pyromaniac]

m not too sure but i made a similar mixture. it is
16% sulphur
16% charcoal(I dont know wich wood to use but I used willow)
68% potassium perchlorate

take care
I found it a bit dangerous when I made it at the age of 11.

Never confuse with potassium chlorate & potassium perchlorate.
In this case potassium perchlorate is used. Dont use potassium chlorate as it becomes very dangerous when it comes in contact with sulphur.

Let me tell you again
m not sure but I think that this is the same as the one used in rockets.

[spanner]

The purplish color you mentioned could be the result of there being KClO4 in the fuel. A "quick and dirty" method of testing for potassium perchlorate is to mix it with sugar and watch for a violet flame coloration.

The pieces you describe that seem metallic, probably are. The material isn't well enough integrated into the fuel to be of much use except as an enhancement to the tail as the rocket ascends.

The burn rate you describe doesn't really tell the whole story. When burned confined, some fuels will burn MUCH more rapidly, than when burned unconfined. Smokeless powder is one example of this phenomena.

Please don't try to replicate the fuel by using anything I've mentioned. There are dozens of good, safe fuel formulas- but the best by my way of thinking, is black powder.

It's relatively safe, and powerful enough for most anything that you're likely to need it for, IMHO.

Edited by spanner, 10 January 2007 - 03:35 PM.

[maxman]

It wasn't really purple. It was slightly pink if anything bordering towards the red.

What looked like titanium peices gave no effect to the tail at all. I have titanium and even a very small amount added to BP gives an amazing white tail. I have a few pictures but am unsure how to upload them here.

[spanner]

It wasn't really purple. It was slightly pink if anything bordering towards the red.

Sorry, my bad.

What seems to be assured is that the fuel isn't straight BP- that much you already know.
There's another chemical involved that gives a "pinkish" cast to the flame.
It burns slower than BP when unconfined.
It contains metallic grains of unknown composition.

Being a mass-produced, relatively inexpensive device that has to also be relatively safe to operate, the choices are limited somewhat in what the fuel comp could be.

Is there a way to access a MSDS or the equivalent, to see what chemicals are present? This could give you good insight as to what's contained in it.

[pyrotrev]

From the dimensions given, it sounds like a typical BP motor. However if there's really no tail whatsoever and a strongly coloured flame then maybe it's a perchlorate based fuel - I've heard that some of the larger rockets are using this (basically a denatured, stabilized whistle mix) for greater power given the limitations of max. calibre to meet 1.4G.

Edited by pyrotrev, 11 January 2007 - 10:13 AM.

[maxman]

Well I wouldnt say its a strongly coloured tail at all. When the rocket flys it looks like a regular BP rocket not a streaming charcoal tail as in a core burner but possibly a little more than an end burner. The pinkish tinge can only be seen when burning loose on the ground (I have vids) although vids can alter the colour perception you can see what I mean from it. I just looks and sounds different to bp meal etc