Many rocket failures

[Mario1]

Ok so here goes nothing. First rocket I used today went all over the ground and shot at my neighbors car. Great....Next Rocket shot out into the grass and then right into another neighbors house. My dad kinda banned me from rockets but I still want to know what I did wrong. The propellent was 65/35 kno3 sugar ball milled for 4 hours. The tube was a 3/4 in ID that was 2 inches long. The stick was a 5 inch stick. I think its stablization issues because the thrust is good but they fly in all the wrong directions.

[NightHawkInLight]

Ok so here goes nothing. First rocket I used today went all over the ground and shot at my neighbors car. Great....Next Rocket shot out into the grass and then right into another neighbors house. My dad kinda banned me from rockets but I still want to know what I did wrong. The propellent was 65/35 kno3 sugar ball milled for 4 hours. The tube was a 3/4 in ID that was 2 inches long. The stick was a 5 inch stick. I think its stablization issues because the thrust is good but they fly in all the wrong directions.

Use a longer stick. Also, since you're in range of others homes and belongings, I very much suggest you find a new testing ground. You're very likely to get someone mad enough to call the police at this rate.

[Mumbles]

Yeah, add like another 2 feet or so on that stick and you might be in the ball park. It's not necessary, but a good rule of thumb is to make it balance just below the nozzle. Also, try getting a new testing area.

[Mario1]

Ok Ill try a bigger stick. But Im not sure if my propellent can lift it. I dont want it spinning out of control again. There is a field down the street from my house but wont I look weird carrying a rocket with me on my bike? Wouldnt want to bump into any cops on the way there.

[Twotails]

I too have had this happen to me, I use the mixture 75% KNO3 25%sugar(powderd), reduced to a fine powder, then packed into the tubes. I also used the tellaflight formula that uses KNO3/Sugar/Sulfur, I dont like using the formula using sulfur, it smells.

[firetech]

Endburning sugar rockets will not work below 3/4'' ID (at least to my knowledge, because I have not tried anything larger). They MUST be cored. 1/4'' nozzle throat for 3/4'' ID and 1/8'' nozzle throat for 1/2'' ID. The core length is debatable and you can work on that on your own. When you're just starting, don't bother with teleflite propellants and odd mixtures. Just simple 2:1 KNO3/Sucrose works fine. My first successful attempts were 3'' length of 1/2'' ID tube. With a kitty litter nozzle about 3/8''. 1/8'' nozzle throat and a 2'' nozzle depth. Start with static tests. You'll know for sure by the sound it makes at max thrust if it can lift itself and a stick. Good luck.

[Mario1]

I dont really understand this cored stuff? Whats a core?

[Xtreme Pyro]

I dont really understand this cored stuff? Whats a core?

 

A core burner is exactly how it sounds the rocket has a "Core" all the way through the rocket motor up to the end plug. Here is a diagram:

http://www.zephyrlabs.org/wordpress/wp-content/uploads/enginev1section.png

 

An endburner has no core, diagram:

http://www.skylighter.com/images/newsletter/117/rocket-engine-diagram.jpg

 

Im sure someone else can explain it better than I can, but oh well at least I tried

 

EDIT: AH sorry for the first picture being so big

Edited September 4, 2009 by Xtreme Pyro

[Mario1]

So and endburner rocket is for say a model rocket? Like the kind you can buy in a kit and build youself? And a cored one if for rockets like the ones ive been making. Just a tube and a stick.

 

and for the endburner would the ejection charge be blackpowder? I dont want my rocket to explode and my BP is powerful enough to do that to my tube casing which are very thick.

Edited September 4, 2009 by Mario1

[firetech]

Before you go any further I suggest you do some more research. AKA lots of reading. Start here www.jamesyawn.com

You can even email him personally with any questions you want answered.

[Arthur]

Mario1 what you did WRONG was to test a device within proximity of property. No doubt, no debate that was WRONG.

 

What you could learn from are all the aspects of composition tube and stick. A rocket will travel, you need a space big enough for it to travel in any direction without even coming close to property.

 

If you can get your dad back on your side then get him to help you take a rocket to somewhere out in the sticks, somewhere at least a mile from any property.

[Gunzway]

Mario1 what you did WRONG was to test a device within proximity of property. No doubt, no debate that was WRONG.

 

Big keyword there, not only did you set off a rocket within what sounds like a close suburban area (rockets are perhaps one of the worst in these scenarios) but it was your first one too! Always do first devices in generous amounts of space and always start small so the consequences will be ditto. Though I totally agree, you shouldn't be doing anything mildly close to a property; if you have tested a device many times and have some sort of consistency (tooling, press etc.) you could possibly decrease the amount of land but the more room the better. Unfortunately, I don't have the land I wish I had but I always make my rocket sticks slightly heavier than my rockets (apparently it will just decrease my rocket's apogee, the other way around and it will be more unpredictable). I also aim my rocket in a direction (over a river and into vast space) and as long as it doesn't go backwards it will be no problem; if it does, well that's my house.

[dagabu]

Big keyword there, not only did you set off a rocket within what sounds like a close suburban area (rockets are perhaps one of the worst in these scenarios) but it was your first one too! Always do first devices in generous amounts of space and always start small so the consequences will be ditto. Though I totally agree, you shouldn't be doing anything mildly close to a property; if you have tested a device many times and have some sort of consistency (tooling, press etc.) you could possibly decrease the amount of land but the more room the better. Unfortunately, I don't have the land I wish I had but I always make my rocket sticks slightly heavier than my rockets (apparently it will just decrease my rocket's apogee, the other way around and it will be more unpredictable). I also aim my rocket in a direction (over a river and into vast space) and as long as it doesn't go backwards it will be no problem; if it does, well that's my house.

 

Sugar rockets can be tricky. I have had J motors CATO and destroy a $2000.00 rocket and the telemetry equipment

 

I agree that a 2:1 ratio is about the best place to start and then dial it up to the Teleflight recipe as you get good results. James Yawn and Richard Nakka are the guys the rest of us HP rocket guys follow.

 

http://www.nakka-rocketry.net/

 

NEVER:

-Use PVC for motors

-Launch your rockets where they can do damage to anyone or any thing

 

READ, READ, READ! Build later, these things make some fearsome thrust!

[PyroMan16]

Ok Mario1 your a bit confused. All you need to do is go to Youtube and type in "Kno3me". Then go to his videos and one of them is just a simple " how to make a PVC rocket engine". Do exactly as he does besides use paper tubing instead of PVC. You don't need an ejection charge or anything just endplug, fuel, nozzel.

 

You could also try adding a bit of Red Iron Oxide to your sugar mix. It boosts speed a bit. You could also decrease your nozzel size a bit, just as long as it doesn't blow.