35 replies to this topic

[jcow]

Always, in pyrotechnics, including rocket props, measurements are by *weight*.

ok, silly me. forget everything i've said about my compositions! there were all measured by volume. time to start from scratch again. suppose i read a recipe for a composition measured by volume and i stuck with it.
thanks.

[EnigmaticBiker]

ok, silly me. forget everything i've said about my compositions! there were all measured by volume. time to start from scratch again. suppose i read a recipe for a composition measured by volume and i stuck with it.
thanks.

Using volume is a problem because volume can change depending on what form the chemical is in.

Using weight means it's repeatable and chemical equations can be converted directly to compositions.

Read pinned posts in Pyrotechnic Chemistry section etc. It may save you a lot of hassle/limbs.

No amount of help with compositions will work if you don't understand the basics.

[selwyndog]

I've used sodium nitrate for years as it was freely availble in a local hardware store for about £2 for a few kelo's. Sodium Nitrate has a lower molecular mass so not as much is requires 101g KNO3 can be replaced by 85gNaNO3.Sodium nitrate is also more reactive than it potassium counterpart so theoretically GP made with this salt is both more energetic and rapid in it's reaction, however it's hygroscopic behaviour tends to slow the material down with storage. It can be dried off in a flat pan heated with steam after which it's speed is restored.
The composition I usually use is 170g NaNO3, 32g S and 36g C. Rockets made with this composition have flown very sucessfully

[icarus]

sodium nitrate is ok for white smoke with sugar and melted paraffin wax as the wax overcomes the hygroscopic nature of NaNO3

[MDH]

Sodium nitrate makes an excellent yellow with magnesium, provided the stuff is dichromated.

[GalFisk]

You may treat the Mg with linseed oil, dichromate is only neccessary when it is used in conjunction with ammonium perchlorate.
Sodium nitrate+sodium benzoate 60/40 gives a nice orange flare as well. +10% MgAl increases the brightness. I'll try sodium nitrate+MgAl some time.