8 replies to this topic

[wjames]

can someone point me in the right direction for info on rocket propellants.

ive been using std BP, with fair results....ive also tried uping the charcoal %.

best result ive had so far was 37.5:37.5:10:5 KN03:sugar:charcoal:Sul.

decent burn rate, very noisy in a 3/4 x 3.5 inch tube, but cato every time in 2x6

im not firing these with any payload, at the moment.


im open to any suggestions...

[bigtonyicu]

can someone point me in the right direction for info on rocket propellants.

ive been using std BP, with fair results....ive also tried uping the charcoal %.

best result ive had so far was 37.5:37.5:10:5 KN03:sugar:charcoal:Sul.

decent burn rate, very noisy in a 3/4 x 3.5 inch tube, but cato every time in 2x6

im not firing these with any payload, at the moment.


im open to any suggestions...

Wow that fuel is WAY under oxidized you must get a very smoky slow burning fuel.

As for your CATO are they core burners?

As for a better Mix I use

65:15:8:12 KNO3:C:C6H12O6:S

It's a cross between RCandy and BP propellant reliable performance, stable regression rate, slightly under oxidized to slow it down, LOTS of smoke, only downside is like any RCandy Propellant5 Slightly hydroscopic, cover the nozzle it aluminum tape once hardened and you'll be fine.

[wjames]

is is under oxidized....and a bit too smoky....but it did lift cleanly, and seemed stable.....

i presume you cook it ? kno3 and sugar first, then carbon and sulf????

ive seen a rocket with a similar compo.....he cooked it, cooled it, then ground it up, and pressed it into the housing.....

yeah, the cato's were core burners.

im hoping to make a larger bp rocket 2morrow....got a nice peice of PVC pipe here, 40mm id 240mm long.........any suggestions.

[bigtonyicu]

I cook the sugar, KNO3, and charcoal together in a double boiler (oil not water in the bottom) I monitor the temp in the bottom... it must stay bellow 275 C (for safety, KNO3 melt around 335C, anything bellow that will not ignite) it is very thick, I then and the spread it out on to a cookie sheet covered with Teflon and once dry I break it up and ball mill with Sulfur, I then Press the mix much like a BP rocket.

More work then BP but it's more stable and consistent.

I've even make large batches of it and it stores nicely in a zip top bag in the freezer until ready to press.

[bigtonyicu]

as for your cato,... what's happening is at the burn progress the surface area increase, that increases the pressure and eventually the tube explode from it... making the nozzle bigger should solve it.... but with the strange fuel you're using i can't guess of the size to go with... i'd try 3/32" bigger diameter... no easy answer but lots of trial and error

[portfire]

im hoping to make a larger bp rocket 2morrow....got a nice peice of PVC pipe here, 40mm id 240mm long.........any suggestions.

Yeah, DON'T use the PVC pipe!!!!! If you have a CATO and your, or anyone else is close by, have 99 already dialed in your phone and if you have a CATO enter 9 and ask for an ambulance.

There's a thread with all you will need to know about getting your Rockets right, from Comps to formula on Choke/Nozzle size and Core length. ALL you'll have to do is dial your fuel in

[wjames]

yeah, i had that once before with a smaller bore pvc rocket.....thankfully, i launch my rockets from behind protection.....

can you point me in the direction of the magical thread.......please.....

[Arthur Brown]

The PVC will do for a launch tube when you get to bigger sticks! DO NOT put compound inside it.

Have you read any of the respected texts on propellants? COPAE by Davis has several bits especially on the changes in compound needed as the size changes.

A cato is when the pressure builds up faster than the nozzle can let it out. so slower compound or bigger nozzle! Stick to a known mix and vary the tool geometry OR stick to a known tool geometry and vary the mix. If you vary everything then there are too many variables to calculate.

[portfire]

http://www.pyrosocie.......&hl=Rockets

It's great when you use the Search function

Edited by portfire, 03 September 2008 - 08:15 PM.