Hey guys, I have been sitting around work (JCPenney) these past couple of days --because there are very few customers-- cutting up the leftover cardboard giftboxes and rolling them into rocket engine casings (and I have come up with some very impressive ones indeed). However I am looking for a good fuel to use in my rocket and I have 1 pound of pyrodex sitting in my room doing nothing except making for an interesting decoration. I was wondering if there was any kind of binder I can use to mix with the pyrodex to make a satisfiable propellant?

Dextrine or sorbitol would work, i would not recommend sucrose because of it being hygroscopic.

I sometimes use sauce binder (not for rockets though) which is a white powder that gets rock hard after it has been mixed with water and allowed to sit.
Do NOT use KMnO4 in compositions with this cause it will autoignite!

Water will work fine, but keep in mind that Pyrodex burns REALLY fast, even after you've dissolved/binded it, you can also use rubbing alcohol so it will evaporate faster.

Are you using a nozzle, or are you going to make a core burner?

[ January 09, 2002: Message edited by: BoB- ]</p>

Current progress on my rocket:
(I am taking pictures of every step as I go; however, I am too lazy to go buy a digital camera, so I have to wait until I use up the film and develope it.. then I will scan all my pictures and post them)

Body/Casing: PVC pipe
*--*1'10" long
*--*2" diameter from inside wall to inside wall
*--* ¼' wall
*--*rated at 280psi

Nozzle : (very thin and tightly rolled cardboard soaked in rubber cement and finished off with super glue.. then the inside covered in 3 layers of aluminum foil)
*--*4" long
*--*½" opening in center

Engine (because I didn't feel like filling the whole case with my fuel)
*--*1' long
*--*fuel is approx. 2.5 parts pyrodex to 1 part rubber cement
*--*total fuel weight: approx. 19oz
*--*shape of dried fuel in engine:
<pre>
---------
| |
| |
| |
| |
| |
| |
| |
| |
| |
| . |
| : : |
| : : |
|: :|
</pre>
(I make this opening in the fuel by sticking a small funnel in the binded fuel as it dries.. the purpose is the increase the surface area)

Ignition: (three possible ignition types so that I know for sure it will work)
*--*First ignition is a commericial fireworks fuse embedded into the fuel and run directly out the nozzle
*--*Second is another fireworks fuse that leads to a small charge of pure pyrodex that is taped to the inside of the nozzle (near the actual fuel) and then run out through the nozzle
*--* Third (and for a last resort) is a stick lighter made for lighting firecrackers which is embedded in the center of the fuel and sticks straight out

Fins: (compressed cardboard cut with a saw)
*--*2 large fins (1' long and 6" wide at base) and 2 small fins (4" long and 2" wide at base)
*--* fins are approx. ¼" thick

Standoffs: (so I can light the hanging fuse without an actual platform--compressed cardboard)
*--* ¾" wide and holds the rocket 4½" from ground
*--*I am using 4 standoffs that are hotglued to the outside to the rockets base

--------What I still have to do--------
*--*put on a payload.. I think this may just be some lightweight plastic or cardboard cone.. it really doesnt matter because the engine stops 1' below the top of the rocket
*--*make some sort of improvised launch pad.. probably just a ¼" steel rod in the ground with a ½" wide small PVC pipe glued onto the rocket that will sit around it
*--*take some pictures and hope all these hours off work and the money it cost to buy the materials wasn't a complete waste!
*--*I will set it off at approx. 5:00pm tomorrow (central time) because I have a few friends that want to watch

-----------------------------------

If you think that anything I have used or done on this rocket may cause it to malfunction, please tell me before I set it off so there might be a chance I can fix it before hand!!!

One more thing, I see the acronym 'BTW' used a lot on this forum.. what the hell does it mean?!?

[ January 10, 2002: Message edited by: NoltaiR ]</p>

BTW = "By The Way"

You did tests before hand that the mixture of pyrodex and rubber cement burns correctly right?

I think if it doesn't explode, or have insufficient thrust, or fly in an out of control fashion, then it should work very well :)

Find a wall or deep hole to hide from the rocket, as homemade rockets have a bad tendency to go in directions other than up.

I did many, many tests on finding pyrodex a suitable binder before I came across rubber cement as the one. I tried a variety of other glues and sealants but the others never had complete combustion and always lowered the power of the fuel dramatically (enough that I doubt it would never have gotten off the ground) as well as the left far too much residue which probably would have clogged up my nozzle. Rubber cement is perfect, and if anyone else attempts this same project, a tip I can give is that: my 2.5:1 ratio is just a approx. estimate that I made after mixing it until there was enough to hold it together but not enough that if would lower the velocity of the deflagration rate (the real ratio could be anywhere from 2:1 to 3:1).

Rubber cement actually seems to greatly increase the burning power without necessarily causing it to use up fuel faster... a charge of unconfined pyrodex (about 25g) ignited makes a flame about 6" to 1' high, while a 25g mix of my fuel (pyrodex and rubbercement allowed to dry) unconfined, makes a flame about 3'-4' high.

Anyways I just have to make sure that the mixture isn't too powerful as a fuel (as I will soon find out in a couple of hours) because it could either blowmy nozzle out of the pipe (which its going to take a hell of a lot of pressure considering all the glue that is on there) or just blow the whole pipe to peices.. and I am having second thoughts about making a cone-shaped hole in the fuel for surface area because the fuel will already be extremely powerful. But one thing is for sure, if it survives the first 5 seconds, then it will be flying for a while.

Maybe you guys can help me with this: If I want to calculate/find the hieght that my rocket could go (at least theoretically at the moment), how can I go about doing that?

One more thing (concerning nbk's post about the direction)... I have been worrying about that as well (which is why I have 4 fins and am using a launch pad with a rod that is 4' high) because even most all commercial fireworks rockets rarely go straight up, so the slightest tilt that my rocket may accidently have, will result in a big difference over a large distance. I live in one of the rural areas of my county but I am surrounded by small subdivisions that are about 3 miles in every direction, so I don't want the police called on my ass because a rocket fell in their yard and set something on fire.

Rubber Cement.http://tuffware.com/arts-crafts/glue/cement.jpg


Is this just glue? Like PVA glue?
[edit for link incorrectly input]

[ January 10, 2002: Message edited by: RTC ]</p>

The rocket was set off about 30 minutes ago and became a terrible.. failure :mad:

Problems:
Nozzle:not stuck in the casing well enough.. with the initial ignition the glued cardboard nozzle was crushed and blown out of the casing.

Fuel:Not enough binder!!! (and yes I was talking about rubber cement as you have pictured there). I noticed the problem even before I ignited the rocket because everytime I would turn the rocket upside down I heard the sound of it falling back and forth.. which also means there was the infamied gap in the fuel!!

Ignition: the commercial fireworks fuse was not sufficient enough to ignite my fuel. I made a quickmatch fuse and taped it to a charge of pure pyrodex which (although it ignited extremely fast.. about .5 seconds) ignited the fuel great.. however if the rocket would have taken off then the fire would surely have poured down on me because I didn't have enough time to get away.

Engine: I forgot to glue the endcap of the engine because I figured that the fuel would be solid enough (it wasn't) so that the end cap wouldn't even feel heat or pressure until the last of the fuel was used.

----Future experimentation----

*--*I will have to get some more pyrodex (although it costs $17 a pound) and rubber cement and make a better mixture
*--*try to make or attain a steel nozzle (can I possibly do this with a steel pipe and a torch to heat up the metal?)
*--*seal off the engine completely
*--*I used the cardboard top that I had made for another smaller rocket as the payload for my rocket... it was tightly fit but I did not bother to glue it because I didn't think the pressure would make it past the endcap of the engine.. It did however when the ignition came and the fuel exploded within the engine (drilling a 2" hole into the ground--even though the standoffs held the rocket 5" from the ground), shooting my payload in the air like a mortar shot (the casing remained on the ground :( )
the remaining fuel that didn't burn in the initial blast burned as it was flying in the air

I found the remains of the nozzle, some cardboard, and a couple of the standoffs laying around the ignition site. I gathered all I could find and took a picture of it.

I still have the casing which I will reuse in a future rocket.. however I will obviously have to rebuild an engine.. so it will be a week or so before a another rocket is made. If I get my photos developed before then, I will post them.

Maybe you should check out <a href="http://www.nakka-rocketry.net" target="_blank">www.nakka-rocketry.net</a>

Richard Nakka has a lot of experience in home-built rocket engines, including those in PVC casings...

17$ for pyrodex!! I bought 6 pounds of it at walmart for 3 dollars a pound. It was after deer season so they put it on sale and I bought the rest of it. I thought it would be good for gasoline/naphthalene/cremora fireballs, but it burns way too slow unconfined so it's pretty much useless sitting in the basement.

CylonitePyro,

I prefer BP for proformance but, it is more exspensive and you get less per volume(50% more Pyedex in a can by vol.), and BP is harder to come by In my experments and tests there isn't that much of a Difference... and quite far from being useless

Pyredex is all I use...

(NO Flaming! NBK2000)

[ January 11, 2002: Message edited by: nbk2000 ]</p>

Black powder isn't that hard to come by for me, it's in the army an navy store, or I could make it, it costs 10$ a pound there, or I could get it at gun shows. Black powder seems to burn much faster in my experiences, making Pyrodex not very usefull for my purposes. My only need for Bp is for a shoving charge for fireballs.
When used for such pyrotechnics the Pyrodex just fizzed slowly and the salt and pepper mix didn't go anywhere, bp flashes quickly at just the right speed. Pyrodex is harder to ignite as well.

Hey, sorry for dissin' your propellant of choice.

[ January 10, 2002: Message edited by: CyclonitePyro ]</p>

BP is quite hard to comeby where I live.. it is only sold for muzzleloaders and even then it is a rare site to find. Pyrodex is more readily available and for my purposes, the last thing I need is more power. Although my 'launch' today was a failure (10 hours of work gone...), it was powerful enough to blow my standoffs to pieces as well as drilling a small hole in the ground (as stated in a previous post). If anything, I need a way to lower the velocity of the burn rate for at least the first second or two so that it gradually lifts off then accelerates.

I have no problem in igniting pyrodex and it gains power when mixed with rubber cement. The only problem is that I can't afford to just go out and buy 20 pounds of it to make some full sized rockets (bigger than my foot-long engine) and take a chance on it not working again.. (i.e. 20 lbs x $17 = $340 plus tax).. I will just need to get some more pyrodex and find a way to make it last longer and bind better.

Maybe if you leave out the section made with an upside down funnel in the bottom of the fuel rod you use as in the little picture, just try with a solid stick of fuel, it will have less surface area and give the rocket more time. Hey at least the rocket wasn't a total failure, you got to see? hear an explosion.

Mix some KCl with the pyrodex that's close to the nozzle, this should decrease the burn rate, thereby reducing pressure and temperature and let them rise more gradually. This is important if you've got glued parts cause they can't cope with sudden temperature differences.

[ January 11, 2002: Message edited by: vulture ]</p>

Your are right pryedex doesn't work well in nap. or Salt/Pepper mix Charges. If you need your pryedex to burn Faster(more punch) try adding in Mg in flake or powder form. This is not reccomended for rocket fuel but makes very nice burst charges.

Yeah, thanks for the suggestion I'll try something to get the pyrodex to become usefull because that's a lot of pyrodex to waste even if it was cheap. Magnesium seems like an important element that every pyro should have or attempt to get, I think it's about time I got mine.

If you have the time and patience, you can buy MG pencil sharpners for £0.25 in Partners (in the UK)

It'll take you a while to file it down, but once you do you have about 5grams for a few pence.

Or you could make a little "contraption" that I put together for filing things.

It's just a 30cmx30cm box with no lid, all I do is screw the item im "filing" to the bottom and away I go with the angle grinder with a fine no grit sanding sheet.

Only takes a few mins which is another bonus.

I have yet to restart work on my next rocket but it will happen soon when I have time to buy some more pyrodex.

Anyways the fuel stick will definitely be a complete cylinder this time (rather than with a conic hole in the combustion chamber's area) and I will be using only a improvised quickmatch this time (just a lot longer and I won't put as much pyrodex as I did last time).

Actually the real reason I just posted is because I think I can cut a nozzle out of wood (it is not going to be your everyday nozzle. with the outside being cut away as the inside hole gets smaller. i.e.:
<pre>
.---_ _---.
| -_ _- |
| --- |
| |
| _---_ |
| _- -_ |
'--- ---'
</pre>

Rather, the outside wood will be straight across so that the wall of the wood will increase width as the center hole gets smaller--the purpose of this is so that I can run a screw from outside of the pvc through part of the wood wall (so there is a better chance of the nozzle not getting blown out again). I will obviously have to use hardwood if anything to be able to sustain the extreme heat.. does anyone think using wood (as rediculous as it sounds) as a nozzle is at all possible without it being vaporized immediately.. maybe I could treat the wood with some sort of flame retardant?

[ January 13, 2002: Message edited by: NoltaiR ]</p>

I have made small bottle rockets with pyrodex as propellant before. They were only 5\16 inside diameter by 1 1\2 inches long. but they worked every time. i simply have a jig made that the rocket tube would fit in and then with a 5\16 inch dowel pound in the endcap (wad of kraft paper), pour the pyrodex and tamp it in, and fit a glued-up nozzle in the end with a fuse. for the nozzle, i would roll kraft paper with glue spread on it around an 1\8 inch diameter skewer until it was big enough in diameter to fit perfectly in the tube. after drying, the long nozzle is easy to cut into normal "nozzle sized" lengths with a razor, or in your case, being bigger around, with a saw of some sort. i have used this method for larger rockets also.. (although not as much) and these nozzles hold up well if they are glued consistantly when rolled. another good thing about rolling your own is that you can make it fit any diameter tube that you like. Aluminum foil would protect it if you were really worried about it getting to toasted.
You might also be better off trying to roll something thicker than kraft paper for your rocket nozzle. A soft, forgiving cardboard would probabally work.

[ January 13, 2002: Message edited by: venz ]

[ January 13, 2002: Message edited by: venz ]</p>

I used to make rockets with whistle mix fuel, I made the nozzles out of wooden dowel segments, they were shaped like this:


| \ / |
| | | |
| / \ |

They worked fine, I recovered some of the rockets, the nozzle was intact and the hole was blackened and slightly enlarged.

[ January 13, 2002: Message edited by: CyclonitePyro ]

[ January 13, 2002: Message edited by: CyclonitePyro ]

[ January 13, 2002: Message edited by: CyclonitePyro ]</p>

So I guess wood could work (and I like the dowel idea although I don't know how big in diameter I am going to be able to buy it).. since you are using whistling mix, I don't suppose your rockets were very large.. do you think that the wood will still work on a rocket with an engine that is 2" wide?

Thank you for your suggestions.. they certainly save me a lot of time and money from having to actually go and experiment every little detail :D

There's a name for hour-glass shaped rocket nozzles and I can't remember what it is... The purpose of them is to increase the speed of the escaping gas though.

A few drops of water glass (sodium silicate?) should fireproof flammable nozzel materials.

If you're worried about the nozzle flying out and you're using PVC motor casings, I would solvent weld a ring of PVC inside the mouth of the motor. The nozzle plug would sit up against this and should give it quite a bit of support.

Not being funny, but maybe you should start with smaller motors? They're easier and less time consuming to make, much less expensive and don't tend to make such a mess when they go wrong.

I will definitely have to start making smaller prototypes first and then moving up.. certainly would save me some $$$ but I don't know if there will be problems that show up ONLY when I am using a 'full size' engine. Someone in an earlier post had asked me if I was using a core burner or a nozzle.. I am obviously using a nozzle but what is a core burner? Is that what is used in bottle rockets?

I was reading through the old archives and there was a topic on putting a primary at the end of a rocket (january 2000 archive) as a payload.. this would make it a missle more than anything but I like the idea and I may do some experimentation with it.

A core burning fuel grain has a central hole that runs through most of the length of the grain, like lots of Polo mints stacked on top of each other. The purpose is greatly increased the burn rater compared to an end burning (solid) fuel grain.

I believe the word you're looking for is "bell nozzle".

Polo mints you might know as lifesavers.

As someone has suggested before, you REALLY should spend a bit more time on Richard Nakka´s excellent site. There are loads of others describing how to build rockets. It sounds like you´re well on the way with testing etc. Search the web for home made rockets, blue strobe, BP nozzle-less, dollar rockets, the list goes on.

I fucking wish I could buy pyrodex or BP at Wal Mart. :mad:

While I´m on the subject, the name of the narrowing of a nozzle is a VENTURI, and a bell nozzle is a variation on that. A web search will teach you about them and the complex theory behind their design. It´s the same principle as gives an aeroplane wing it´s lift. Think of the inside of your nozzle as a cylindrical wing, sort of thing and you get the idea.

Nozzle´s are most simply made with durum´s rock putty (I think it´s called), don´t know if it´s available outside the US. I reckon a good way to make a pretty good venturi nozzle would be to fashion a mandrel to the shape you want, then pour plaster of paris in from the top. Heatproof and very smooth if you get it right. (You might have to make some type of tool to shape the plaster on the inside of the rocket body)

Skylighter will ship cardboard tubes (for rockets or any pyro) anywhere in the world.

If you build a core burner, you should light it from the very top of the core for maximum efficiency. The best way to do this is to fill it with BP, or get an electric match in the top somehow.

ALSO (bugger me I´m running out of time) if you want to build a stable, stickless rocket, you can try to drill 2 small holes in the rocket body, above the nozzle plug. Gas will then vent out of those, almost like a "Q" with two opposing tails, and cause the body to spin like a rifle bullet. One day, I want to make my own model Katyusha like that, lot´s of pipes, all electronically fired. :D

But I say again, if you want to find out more about rocket design, get searching, there is a shitload out there.

Curse my memory, venturi is one of the words I considered when trying to remember what it was called but I dismissed it.

I think that filling the entire core with primer composition may risk damage to the fuel grain, especially a brittle one like pressed BP. I found a generous sprinkle of BP was enough prime KNO3/sugar motors.

Here's a good link about spin-stabilised motors:

<a href="http://www.ctel.net/~dwilliams/stinger/steenger.html" target="_blank">http://www.ctel.net/~dwilliams/stinger/steenger.html</a>

I normally use KNO3/sorbitol/sugar (65/20/15, I add sugar to save on the more expensive sorbitol), unrestricted fuel grains with a core, meaning they burn on the inside, outside, and the two ends. My nozzles are 1" thick MDF cylinders, with the internal shape machined with a router. I use hard cardboard tubes, roughly 1" ID, 3/16th" walls, 5" long. To stabilise them I use a few feet of 1/4" dowel.
They *normally* go straight and don't explode!

I also had a go with AN composites, but they're more complicated and not really worth it, since I can't get Mg to make really good ones.

Cool link for the steenger missiles there Anthony, that guy has his shit together eh? The kind of pyro I aspire to be. I love his quote

"Sometimes, when the urge strikes, the smoke addicted pyro just needs to throw something together quickly to get him through a long day". :D

Can´t remember who, but someone said to be careful with pyrodex, as it burns fast, so here´s another idea. Having had the joy of popping off a few 66mm LAW´s I can tell you that the propellant on those burns VERY fast indeed. So much so that it´s all burnt before it leaves the firing tube. I still have a motor body somewhere and it´s made from turned aluminium with an od of about 2", with walls about 5/16" thick and a nice shaped bell nozzle at the end.

If you have unlimited access to pyrodex, :( why don´t you have a play with some VERY strong, core burning rockets with much less binder and more fuel. You´ll have either a large bang and lots of pieces of motor, or a large bang and a rocket travelling at high speed. :D

And another question out there for all you keen rocketeers, is there anything wrong with drilling a core/multiple cores in a caramel candy (or for that matter any) rocket? Most people seem to use a mandrel and tamp or cast it, but the mandrel seems complex and slow. I just imagine doing it with a 1/4" hand drill or something. btw, I like the idea of a core burner working from the top AND bottom together.

You can't drill KNO3/sugar because it's very brittle, but you can drill KNO3/sorbitol or KNO3/sorbitol/sugar since it stays soft for quite a while before it actually cures completely. The friction is enough to melt the propellant, and give a nice smooth surface to the core, but it won't ignite it if you're using a normal drill.

I found the KNO3/sucrose mix to stay quite sticky and held togther well when drilling a core. Unless you clean the drillbit well it will be ruined over time, the fuel stuck to it will attract moisture and it rusts the bit quickly.

It should be down slowly to avoid heat build up from friction. Personally I'd be a bit worried if it got hot enough to melt the fuel!

It doesn't seem to matter if the core is a little off straight, the rocket still seems to fly reasonable straight (stick stabilised).

Making a madrel is easy, all you need is a couple of squares of wood and a round headed nail. Cut the nail to length and round off the cut end, drill a hole to fit the diameter of the nail shaft in one of the blocks of wood (make it tight). Push the drilled block over the nail up to the head, glue this head down onto the second block of wood so the head of the nail is sandwiched between the two blocks of wood. The mandrel is even simpler but requires more care if you haven't got a drill press. Stick a length of wood/non-ferrous metal/hard plastic dowel in a vice, make sure it's nice and stright and the carefully drill into the end. Go slowly and look at the drill bit from different angles to ensure it remains stright in all axis'.

What about a fuel stick like this WHILE USING A NOZZLE:

<pre>
|------|
|1./\ | 1. = Fuel
| || |
| | | |
| | | |
|| ||
|| 2. || 2. = Combustion Chamber
'' ''
\\ //
\\3.// 3. = Nozzle
|| ||
// \\
// \\
</pre>

Not sure if my drawing gets the point across but the the fuel is drilled in the shape of a long, narrow funnel that extends all the way to the payload. If a nozzle could be made to withstand this kind of pressure then the rocket would reach the maximum speed a rocket could reach for its size. The pressure, however, on the nozzle would be overwhelming and the a pound of fuel would probably be used up in a matter of seconds... it would also take a very strong steel casing to hold this kind of pressure in.

Other than that I am trying to memorize the whole Nakka rocketry site :D

I have been doing some static testing with nozzleless H3 (KClO3/C) engines.
They seem very promising; high burn rate, powerful thrust and the H3 is easily compressed which assures long burntime and no explosions.
It is also very easy to produce large amounts and high quality H3. I've been grinding amounts up to 50g in my coffee grinder without accidents.

During one of my tests i put one of them in a hole in the ground, the exhaust pressure made a tunnel of ca. 20cm in the ground by compressing earth :)

The combustion chamber was made of a sheet of A4 paper which was cut into 2 and then rolled around a marker. It was completely intact after burnout.

Launch test with nozzle failed due to high wind speed (we have had rain and winds up to 120km/h for more than a month now in this shitty country! Every rain record has been broken :mad: )
Which caused the exhaust to cut through the nozzle on one side and set fire to the engine chamber. This was extinghuised by the wind and the majority of the propellant didn't burn.
A new test is scheduled for when i have more time.

Bringing back an old but still interesting thread (I think). This seems to be the only thread that deals heavily with the general structure of a rocket rather than the fuel inside, but all the same I think this topic is quite commendable.

Anyways H3 would be an awesome fuel although due to the amount of energy produce, it will definetly be a trick to make a nozzle that can hold it, but if you can then you have accomplished one of the biggest problems that experimental rocketeers face!