problem kno3/sugar rocket

[dagabu]

Can i ask something else ? it is necessary to add multiple rcandy grains into the casing or you can add also one big grain ?

 

You can make one big grain but it is very difficult to cast.

[dan999ification]

yeah air bubbles between the grain and motor casing are not your friend, most likely end in cato. spaced out single grains have the abillity to take fire at once as the pressure drives it into all the grains making the overall burn time shorter and pressure delivered faster

dan

[THEONE]

yeah air bubbles between the grain and motor casing are not your friend, most likely end in cato. spaced out single grains have the abillity to take fire at once as the pressure drives it into all the grains making the overall burn time shorter and pressure delivered faster

dan

 

I saw

video and if you look they say than he had a CATO because he use only one grain.... Edited April 12, 2011 by THEONE

[dan999ification]

his engine blew because the casing wasn't strong enough for the pressure being built up by the fuel

one grain or multiple grains the casing needs to be strong enough for the pressure. pvc pipes whatever the pressure rating dont like spike pressure and shatter.

dan

 

 

[THEONE]

Every time you make a bigger core and longer core and you add more fuel into the casing, the more bigger nozzle you need, so it is possible to add so fuel and have so much big core so the nozzle it doesnt need , the nozzle will be the same casing... those are the nozzless rockets and because i have a fast burning fuel that is i sopouse to do... than you think boys ?

[optimus]

Every time you make a bigger core and longer core and you add more fuel into the casing, the more bigger nozzle you need, so it is possible to add so fuel and have so much big core so the nozzle it doesnt need , the nozzle will be the same casing... those are the nozzless rockets and because i have a fast burning fuel that is i sopouse to do... than you think boys ?

 

Fast-burning fuel is perfect for nozzleless rockets, go for it. I use straight meal in nozzleless 1/2"ID rockets and they're great.

[dan999ification]

if your fuel is fast enough a nozzleless endburner or cored should fly but i doubt it would work with anything bigger than 1/2"id.

dan

[THEONE]

if your fuel is fast enough a nozzleless endburner or cored should fly but i doubt it would work with anything bigger than 1/2"id.

dan

 

I am going to use a 3/4' nozzleless cored rcandy rocket...

 

It is possible to make an nozzleless 1 - 2 inches correct ?

I think nozzleless are more better because the only think that you must to be care is the core length...

Edited April 13, 2011 by THEONE

[dagabu]

For all practical reasons, a "nozzleless" rocket is the same as a nozzled rocket except that it has no nozzle! As the fuel burns away, the pressure and IR radiation increase the burn rate of the fuel creating a pressure spike. This happens even in end burners but on a much smaller scale.

 

With a nozzleless rocket, as the fuel starts to burn away, the "nozzle" opens up allowing for a gentler thrust curve and greatly reducing the probability of a CATO. But with everything, there is a cost... thrust.

 

The nozzleless rocket is not a new idea, it has been around as long as whistle rockets have been in existence but has become and outstanding way to test hot fuels without worry of over-pressurization.

[THEONE]

For all practical reasons, a "nozzleless" rocket is the same as a nozzled rocket except that it has no nozzle! As the fuel burns away, the pressure and IR radiation increase the burn rate of the fuel creating a pressure spike. This happens even in end burners but on a much smaller scale.

 

With a nozzleless rocket, as the fuel starts to burn away, the "nozzle" opens up allowing for a gentler thrust curve and greatly reducing the probability of a CATO. But with everything, there is a cost... thrust.

 

The nozzleless rocket is not a new idea, it has been around as long as whistle rockets have been in existence but has become and outstanding way to test hot fuels without worry of over-pressurization.

 

I tried some compositions of the fuel-core and sometimes the grain comes out of the casing, this is a kind of CATO so i must reduce the fuel-core ?

[dagabu]

I tried some compositions of the fuel-core and sometimes the grain comes out of the casing, this is a kind of CATO so i must reduce the fuel-core ?

 

Nozzleless rockets are pounded or pressed into the tube at high pressures, 5000-9000 of pressure is used to form hard grains in several increments, *R-candy is almost impossible to press into a tube since it just relaxes and de-bonds from the tube when the pressure is removed. One would have to cool the fuel, grate it and ram like BP.

 

*Hot cast R-candy

[THEONE]

Nozzleless rockets are pounded or pressed into the tube at high pressures, 5000-9000 of pressure is used to form hard grains in several increments, *R-candy is almost impossible to press into a tube since it just relaxes and de-bonds from the tube when the pressure is removed. One would have to cool the fuel, grate it and ram like BP.

 

*Hot cast R-candy

 

I have never thought that it will be so difficult to make a simple rocket....

[dan999ification]

I have never thought that it will be so difficult to make a simple rocket....

 

with every challenge comes rewards.

ive had the same sort of problems with my r candy where from what i could work out the fuel grain if not pressed properly can move and let pressure build up at the ends shooting the grain/s out

[dagabu]

I have never thought that it will be so difficult to make a simple rocket....

 

They are not hard to make, the Chinese have been making black powder rockets for a thousand years (more or less) and all they had were the chemicals, bamboo and simple hammers.

 

Give me two hours and I can make a working BP rocket in a hardware store from the items on the shelves.

[THEONE]

It is possible to make my nozzles- end plugs stronger ? I use powdered cat litter...

[dagabu]

Add 1% wax and it will consolidate better.

[Mumbles]

Also, if you are not doing so, recessing the nozzle part way into the tube vs. having it flush with the end will help to prevent blow outs. I'm not sure if you meant physical strength, or binding strength. I've seen others press nozzles dampened with linseed oil. When they dry, they become harder, but that takes a while. I believe WSM has some experience with that.

[THEONE]

The compressing sistem that i use is this one on the picture and i use 3/4" PVC pipe for casing... also i use an iron hammer to compress the mixture

I have seen is some videos that they use a rummer hammer or they put rubber on the top of the compressing tool... me i dont put something like this...

[Mumbles]

For the best compression you'll want real tooling. Something the same diameter all the way down. That will provide the most tooling in the center and less the closer it gets to the walls. This could almost certainly create issues for the nozzle. Ramming also provides lower preforming rockets than proper pressing.

[THEONE]

The nozzle-end plug made from cat litter clay i must compressed them little by little like the fuel or not ?

[dagabu]

The compressing sistem that i use is this one on the picture and i use 3/4" PVC pipe for casing... also i use an iron hammer to compress the mixture

I have seen is some videos that they use a rummer hammer or they put rubber on the top of the compressing tool... me i dont put something like this...

 

There are more things that are wrong with your process then there are right. Carbon steel has no place in pyro, a glancing blow with a steel hammer on a steel rammer can and will cause a spark, I have sparked a thousand nails when re-roofing and hammering by hand will get a glancing blow eventually. That is a fools game you are playing.

 

You have not indicated what country you live in but I take it that you live in a place that has access to a hardware store and you also have the internet. I strongly suggest that you invest in an aluminum ram and a dead blow hammer at minimum so that you dont get burnt due to a stray spark.

 

I also suggest that you stop using PVC tubing for casings, you can roll your own paper tubes for the same price as PVC and you wont be littering the country with PVC.

[THEONE]

I gues your homemade tubes are the problem. For rockets you need really strong ones.

 

 

Works quite well, but you need far more distance to your Rocket as seen in your videos. I believe that If you treat it like you would treat a pipe bomb you are relatively safe. Just keep your distance and watch out for other people around.

And you should not use anything else than betonite for the nozzle, because it works as predetermined breaking point, if the nozzle section isn't to long/strong. If your nozzle fails, your rocket may even continiue it's flight as a nozzleless one, but it's less likely to explode.

 

PVC Pipes seem to be accepted in amateur rocketry, but for the sake of pyro there seems to be no proper substitute to high quality parallel wound paper tubes, intended for rockets.

If you can get them in your country, try them.

 

Edit:

my last succesfull sorbitol Rocket had

-21mm id

-8mm core and nozzle,

-100mm long core

-65/35 Sorbitol fuel with +1% red iron oxide, carfully mixed, molten and casted into the motor.

Didn't have much power.

 

I had more succes with BP.

 

Do you use an end cup ? i was looking for an end cup but i couldnt find,

Also in how much time 1inch of this fuel needs to burn ?

Maybe it didnt have much power because you had a big nozzle - small core

Edited April 19, 2011 by THEONE

[mabuse00]

Do you use an end cup ?

You mean some aerodynamic cone for the top?

No. And I think you should not bother such things at the moment, at least not before you have a reliable engine concept. Thats just fine tuning.

 

Also in how much time 1inch of this fuel needs to burn ?

I didn't measure. Fast enough to let a little lump fly around if you light it.

 

Maybe it didnt have much power because you had a big nozzle - small core

I havent done any futher tests with sorbitol yet, but yes, the nozzle seems to be a little to wide.

[THEONE]

You mean some aerodynamic cone for the top?

No. And I think you should not bother such things at the moment, at least not before you have a reliable engine concept. Thats just fine tuning.

 

I mean something like the photo for the construction of the nozzle-end plug..

So if you didnt use an end cap, which way you follow to do the nozzle-end cup ?

Also did you put a washer ?

Edited April 22, 2011 by THEONE

[donperry]

Believe it or not, my first (amazingly fast) rocket was made of 3/4 Inch PVC, Red dirt (clay like) nozzle and bulkhead, and rcandy from white sugar.

Up to this day that's what i'm using. No cat litter nor bentonite clay.

 

You only need to make the nozzle strong enough. I made mine almost an inch in thickness (from bottom up)

 

If you want to be extra sure you can heat a knife or a screw and make indentations on the inside of the PVC where the nozzle will be rammed. That gives it some more "grip"

over what the plain slippery PVC would give.

Sanding the inside to make it rougher which is even better.

 

Good luck, i have faith in you that it will fly.

 

As for the rocket stick, it Doesn't have to be all that long. 3 ft is good enough for that size rocket.