Fuel increments for 1lb rocket

[Uarbor]

I just have a quick question. I've read through miles of rocket threads and it has been mentioned many times that the height of an increment should not be more than the inside diameter of the rocket tube. But they never mentioned if this 3/4 inch is measured before or after it is pressed. I am currently making one lb black powder rockets on a universal tool set and I am waxing my tubes now. If any of that makes a difference. Edited August 27, 2021 by Uarbor

[SharkWhisperer]

I just have a quick question. I've read through miles of rocket threads and it has been mentioned many times that the height of an increment should not be more than the inside diameter of the rocket tube. But they never mentioned if this 3/4 inch is measured before or after it is pressed. I am currently making one lb black powder rockets on a universal tool set and I am waxing my tubes now. If any of that makes a difference.

When hand-ramming 1-pounders, I use a slightly heaping teaspoon of slightly dampened BP small granulate per increment. So long as your rockets are flying and not blowing up on ignition or soon after, you're within range. With a press you might get away with a little more BP per increment.

 

I don't wax my tubes and don't have issues, but some swear by it. I'd consider tube waxing if I developed problems with poor nozzle retention or CATOs due to poor consolidation.

[Uarbor]

When hand-ramming 1-pounders, I use a slightly heaping teaspoon of slightly dampened BP small granulate per increment. So long as your rockets are flying and not blowing up on ignition or soon after, you're within range. With a press you might get away with a little more BP per increment.

 

I don't wax my tubes and don't have issues, but some swear by it. I'd consider tube waxing if I developed problems with poor nozzle retention or CATOs due to poor consolidation.

I recently built my own electro-hydraulic 12-volt press. I have been experimenting to see what I can get away with when it comes to Black Powder Rockets. Tried it first without my tube support and it crumpled with my spiral wound tube. I have some good tubes from Woody's now but I don't want to waste them on experimentation. I put the tube support on and started making another rocket with half the increments size that I used with hand ramming the tube pulled down almost a quarter of an inch by the time I was done. Rocket still flew but it definitely wasn't pretty. I decided to wax a bunch of tubes since I already had wax and a shotgun swab everything definitely went perfect from there. I was able to double the increments back to what I was using hand ramming and also increased the pressure with no deformation of the tube whatsoever. I was still using my hand ramming dialed in powder and it flew way faster. So I am definitely now firmly in the tube waxing camp. So what you're saying is essentially as long as it's working don't mess with it? I'm going to start on whistle after I master pressing the black powder rockets. I already have the chemicals but I have to finish constructing my blast shield first luckily I have on hand 1/2 inch thick piece of shield from the machine shop I used to work in. I'm planning on building a frame and attaching it to the workbench rather than the Press it will then have a hinge to move it out of the way when I'm not pressing. Right now I am trying to decide if I should use my Universal tooling for the whistle or should I just buy some dedicated tooling for whistle only. I guess I will see how well it does on the universal spindle first it's going to be p-benzo with iron oxide because my Research indicates it would be better for a long spindle. Edited August 29, 2021 by Uarbor

[justvisiting]

Uarbor, the rule is for the height of an increment after pressing. There are different versions of the rule, and the version you report is the tallest increment said to be OK. Lots of folks halve that amount, especially with whistle fuels or with hand-rammed rockets. Most of us go by the volume of an increment in the scoop, not the increment height after pressing. To make all the increments the same height would be an unnecessary PITA, and require scoops of different volumes. Your first increment on universal tooling is considerably taller than the last one, if the same volume of propellant is used per increment. The pressing force is considerably more on the first increment too, if you are pressing to the same force on each increment. In the first increment, you are only pressing the powder area around the very large spindle. The area the spindle takes up doesn't count. The increment above the spindle tip will be smaller when all the same size increments are used, but it's also being pressed without the additional friction of a spindle in the middle of it. I think it all kind of evens out in the end.

 

Steve Laduke is the originator of the universal spindle. He has experimented with altering pressing forces for each increment according to the area taken up by the spindle to make each increment be pressed to identical force, and found it to be unnecessary. I've never bothered with it. Mr. Laduke is very generous with his knowledge, and has been known to help total strangers over the phone because he loves to talk about rockets. A couple of folks I know went to his place and got free rocket lessons. You can do a lot with his tooling. I bought mine from him before other folks started reproducing his tooling, so my comments apply to that universal tooling. My memory stinks, but there is a file online somewhere where Steve Laduke describes the various types of rockets that can be made with his universal tooling. It's probably been linked to around here somewhere at some point.

 

 

I'm glad you saw that the waxing eliminates tube compression during pressing, and the compression wrinkles that go with it. I used to press nozzleless BP rockets on 1lb universal tooling with 8 increments, and they worked reliably to lift 4" ball shells. I used wax in the propellant, or on the tube. Nowadays I wax my tubes and dampen my propellant with water at 2- 2 1/2%, and I use standard BP tooling for BP rockets.

 

For your first whistle rockets on universal tooling, I'd suggest using a waxed tube and a 70-30-1 perc/benz/RIO propellant with 2-3% phlegmatizer. A 1lb rocket on that tooling with that propellant will lift a 5" ball shell no problem. Of course, I'd test a dummy shell first

[Uarbor]

Uarbor, the rule is for the height of an increment after pressing. There are different versions of the rule, and the version you report is the tallest increment said to be OK. Lots of folks halve that amount, especially with whistle fuels or with hand-rammed rockets. Most of us go by the volume of an increment in the scoop, not the increment height after pressing. To make all the increments the same height would be an unnecessary PITA, and require scoops of different volumes. Your first increment on universal tooling is considerably taller than the last one, if the same volume of propellant is used per increment. The pressing force is considerably more on the first increment too, if you are pressing to the same force on each increment. In the first increment, you are only pressing the powder area around the very large spindle. The area the spindle takes up doesn't count. The increment above the spindle tip will be smaller when all the same size increments are used, but it's also being pressed without the additional friction of a spindle in the middle of it. I think it all kind of evens out in the end.

 

Steve Laduke is the originator of the universal spindle. He has experimented with altering pressing forces for each increment according to the area taken up by the spindle to make each increment be pressed to identical force, and found it to be unnecessary. I've never bothered with it. Mr. Laduke is very generous with his knowledge, and has been known to help total strangers over the phone because he loves to talk about rockets. A couple of folks I know went to his place and got free rocket lessons. You can do a lot with his tooling. I bought mine from him before other folks started reproducing his tooling, so my comments apply to that universal tooling. My memory stinks, but there is a file online somewhere where Steve Laduke describes the various types of rockets that can be made with his universal tooling. It's probably been linked to around here somewhere at some point.

 

 

I'm glad you saw that the waxing eliminates tube compression during pressing, and the compression wrinkles that go with it. I used to press nozzleless BP rockets on 1lb universal tooling with 8 increments, and they worked reliably to lift 4" ball shells. I used wax in the propellant, or on the tube. Nowadays I wax my tubes and dampen my propellant with water at 2- 2 1/2%, and I use standard BP tooling for BP rockets.

 

For your first whistle rockets on universal tooling, I'd suggest using a waxed tube and a 70-30-1 perc/benz/RIO propellant with 2-3% phlegmatizer. A 1lb rocket on that tooling with that propellant will lift a 5" ball shell no problem. Of course, I'd test a dummy shell first

thanks for all the information. I have been taking into account the area taken up by the spindle I took the average of the composition area for each rammer and came up with me formula to maintain the same PSI on every section. I had out my micrometer on the spindle and everything LOL subtracted the area of the spindle from the area of the composition without the spindle and averaged it out. I doubt it makes it that much difference but I like to do that kind of math. So I have a table made up so I know what pressure for each Ram for both whistle and black powder in my mind at least I am making the rocket a little easier to get off of the spindle because I am not pressing any harder than necessary.

 

 

My next question would be do you ram the nozzel clay at the same pressure as the composition? I have never had a nozzle blow out but I just started waxing my tubes. So far so good we will see what happens when I'm a hotter fuel

 

I will definitely be using some dummy headers I came up with an idea for dummy headers that don't come back down full. I use sand as my weight and I put a small charge of black powder to eject the sand so it's not so heavy when it comes back down. I'm sure others have I thought of it first No Doubt

Edited August 30, 2021 by Uarbor

[justvisiting]

I've been using the same pressing force all the way up and never had a nozzle blow out, but I mostly do nozzleless rockets. Now that I am using water and FAR less pressing force than before, I press the nozzle at a higher pressing force, just to be on the safe side. The nozzle material bulges the tube, while the propellant does not. If you can feel the bulge of the nozzle area of the tube, it should be good.

 

I have read of a couple guys saying their nozzles blew out of a waxed tube. My guess is that they over-applied the wax by using the pour method instead of the dauber method, or didn't use hot enough wax- or both.

 

Your dummy shell method is a good method. Some folks use bottles of water for the dummy shell, and rupture it with vitamin F in the top of the rocket motor tube.

[Uarbor]

I've been using the same pressing force all the way up and never had a nozzle blow out, but I mostly do nozzleless rockets. Now that I am using water and FAR less pressing force than before, I press the nozzle at a higher pressing force, just to be on the safe side. The nozzle material bulges the tube, while the propellant does not. If you can feel the bulge of the nozzle area of the tube, it should be good.

 

I have read of a couple guys saying their nozzles blew out of a waxed tube. My guess is that they over-applied the wax by using the pour method instead of the dauber method, or didn't use hot enough wax- or both.

 

Your dummy shell method is a good method. Some folks use bottles of water for the dummy shell, and rupture it with vitamin F in the top of the rocket motor tube.

I just made a few more Rockets just now and fired them off. I pressed them all with the same pressure except for the area above the spindle which I gave 25% extra. They flew perfect and the timing is very good.

 

Did you ever wonder what would happen if you packed a four inch ball shell with black cats and mediocre black powder? Well Wonder no more LOL

 

https://youtu.be/5u1BxoAglwI

[SharkWhisperer]

Did you ever wonder what would happen if you packed a four inch ball shell with black cats and mediocre black powder? Well Wonder no more LOL

 

https://youtu.be/5u1BxoAglwI

That's a hoot!!! Niiiice crackle there! Those flashed pretty brightly.

 

New ideas for getting rid of aging small 1.4G articles.

[justvisiting]

Looked good to me