Scudroe - 9-1-2017 at 07:24
Just wondering if anyone here has recently attempted to make a paraffin wax based solid fuel rocket motor?
I had a little trouble believing my own initial calculations coming out at ~70:1 oxidizer: fuel ratio?
I'm planning on a starting mix of KN03 and sugar as usual to attempt to reach ignition of the paraffin wax / KN03 mix.
If it gets anywhere near working there will be other developments.
I won't be doing this for a while, btw (need to fix shed, don't mix in kitchen) so may be sporadic in appearances here.
PirateDocBrown - 9-1-2017 at 07:46
Let's see, 4 moles of KNO3 @ 101g each will produce 10 moles of O atoms, which will react with 5 moles CH2, at 14 grams each.
4x101 = 404 grams KNO3 for each 5x14 = 70 grams paraffin. 5.77:1, more or less.
Scudroe - 9-1-2017 at 08:28
Thanks for the fast response.
Looks a hell of a lot more likely than mine.
But not:
15 (O) + 5 (CH2) -> 5 (CO2) + 5 (H2O) ?
Putting it around 8:1?
The 70:1 I came up with first time out was obviously waaayyy off (and thanks, it matters, have not seen successful examples of this mix to date).
[Will update towards the end of the year on tests].
PirateDocBrown - 9-1-2017 at 13:49
You are much more likely to get CO than CO2.
Scudroe - 10-1-2017 at 01:12
Thanks, makes sense
Will post results in < 12 months for anyone interested.
Σldritch - 11-1-2017 at 11:51
From my experience of potassium nitrate you want fuels that are not very volatile such as sugar or carbon and not glycerol or stearin both of which i
have tried myself.
Stearin gives a nice flame though if mixed with potassium nitrate and sugar 
(Granulated stearin)
PHILOU Zrealone - 11-1-2017 at 14:35
KClO3 (potassium chlorate)/candle wax is also worth a try, need a slight boost to start like sugar/chlorate initiator and some carbon...you need
incandescent C to start it.
Then it burns fiercely, bright and generates a lot of white fumes.
I have made candle wax fumigens with that.
KNO3 will be unsuitable for such a pyro comp because way harder to initiate than KClO3 and much lower production of oxygen...