35 replies to this topic

[Kembang Api]

BigG : I fully agree with your statement as BP waster. If I might add that the rocket?s carry the shell to a higher distance than mortar, would you agree!!!!

Yugen-Biki : I had a same question before, "How did the name "1 pound" rocket come up? Is the weight of the finished motor or the amount that it can lift or...?"
Could anyone advice on this issue!!!!

Base on reference, this is the information that I received from the forum before.
Common BP Rocket Engine Sizes:
Size -------I.D. --------Length
2 oz. ------3/8? --------2-3/4?
4 oz. ------1/2? --------5?
8 oz. ------5/8? --------6-1/4?
1 lb. -------3/4" -------7-1/2?
2 lb. -------7/8? -------10?
3 lb. --------1? --------10?
4 lb. -------1-1/4? -----12?
6 lb. -------1-1/2? -----16?

[Jerronimo]

I haven't made rockets for a while, come to think of it I haven't made any pyrorelated stuff recently.
I'm working on a press and ballmill right now, have to finish those first.

As BigG mentioned rockets are great fun to begin with, but take a long time to perfect when you are attaching payloads.
By the way, I allways use hot meltglue for my endplugs, quick and easy.

[maxman]

Why reinvent the wheel? I vote for clay endplugs (those glue sticks are expensive) and tend to melt over the passfire hole if you are attaching a payload, making them unreliable. If you are worried about clay ends causing extra weight then your rockets have serious problems! I would also be carefull using hot melt, coolmelt is still hot enough to burn your hand let alone what else it could do.

[chim-chim]

Yugen-Biki : I had a same question before, "How did the name "1 pound" rocket come up? Is the weight of the finished motor or the amount that it can lift or...?"
Could anyone advice on this issue!!!!

Base on reference, this is the information that I received from the forum before.
Common BP Rocket Engine Sizes:
Size -------I.D. --------Length
2 oz. ------3/8? --------2-3/4?
4 oz. ------1/2? --------5?
8 oz. ------5/8? --------6-1/4?
1 lb. -------3/4" -------7-1/2?
2 lb. -------7/8? -------10?
3 lb. --------1? --------10?
4 lb. -------1-1/4? -----12?
6 lb. -------1-1/2? -----16?

This topic was covered before but it's hard to find with search so,

Rocket sizes

but it's the weight of a lead ball that fit's in the tube (or ramming sleeve?), which is expected to be 10 times I.D. in length.

[Kembang Api]

Thank you Chim-Chim, Now is clear to me.

Maxman : I had try the end plug clay with a passfire hole, It work sometime but not always. As mention by BigG, it could be the loading presure. I would have to go back and do more testing with different loading presure. Thank you

[Yugen-biki]

Thanks for the help. I have done a searh and I found that page about the lead balls. But I found no sens in the "lead ball" measureing system. Sure, It?s hard to scale rockets but... Forget it.
The important thing is: how big rocket do I need to lift 150g off pay load? http://www.firefox-fx.com/rocketry.htm I?m thinking of buying "ROCSET8" or "ROCSET16".

About the end plug on the rockets. I have found that 75%KNO3 25%Sugar milled for an hour or so, rams rock hard and stops the rocket from blowing out on the top. You?ll just need a few milli meters.
Instead of loadning wet rocket fuel I mill my fuel untill a very fine powder. This helps it to compact much better. I have managed to make rockets without any end plug in the top by using very fine fuel.
A tought: maby very fine BP can be rammed or ppressed on the to to substitute the sugar plug. I have tested this in spolettes but never made the connection to rockets. I have tested graphite instead of tree coal. This compacts good and burns slow.

[alany]

Rockets might take more composition by mass, but the composition need not be as high quality and will still function. Lift needs to be pretty good. I guess getting a rocket to work is probably as much of a challenge as making usable lift, but the tooling is simpler for rockets.

[BigG]

I really can't be sure of why 1lb rocket is called 1lb rocket. I might have to visit some old books to find this information, but I must admit I was wondering about it myself. It could be that this is an upper limit of what can be lifted, but there is a big difference between what the rocket can lift and what it can lift SAFELY? Another good general rule to follow is that for every three grams of BP in the rocket, you can lift SAFELY a payload of 5 gram. As such, a highly compressed tube of 1lb rocket (100 gram?) will still carry only about 160-170 grams of payload. Adding the rocket bp tube, payload and stick will stick get the rocket weight to a maximum of 300g, which is under 1lb. 160grams of composition is a fair amount of pyro. It will take three-inch shell very easily.

So - I'm sure that we can test how much such a rocket can lift - but to get repeatable results it might be a good idea to keep it to the safe limit. I'll post estimated safe payloads tonight.

[Yugen-biki]

Thanks a lot BigG! I think I?ll go for the 1 pound tool. (1 pound ~ 450g)

[chim-chim]

Thanks for the help. I have done a searh and I found that page about the lead balls. But I found no sens in the "lead ball" measureing system. Sure, It?s hard to scale rockets but... Forget it.

Something doesn't make sense for sure,

Shotgun gauges are supposedly the number of lead balls which fit the barrells I.D. and total a pound.

Both can't be true (and I believe the shotgun measurements are) or a two ounce rocket would have the same diameter as an 8 gauge shotgun, and a 10 gauge would be smaller than that. I haven't specifically measured any shotguns, but I'm sure a 10 gauge is bigger than 3/8".

The rocket system might work if it's based on the ramming sleeve, but not knowing case wall thickness, it's not a very accurate system if it works at all.

My apologies for linking back to info that clearly isn't on the mark.

Guess we're all waiting for BigG to "visit the old books' and set us straight.

Edited by chim-chim, 05 May 2004 - 05:06 PM.

[BigG]

Okay, here are recommended safe payloads. For those who can?t handle UK numeric system ? like myself, 1 pound (lb) is about 450grams. There are 16 ounces (oz) to a pound, so an ounce is about 28g and change:

Rocket size ? Payload
2oz ? 1/2oz
4oz ? 1 oz
8 oz ? 2-3oz
1lb ? 4-6oz
2lb ? 8-10oz
3 lb ? 12-14oz
4 lb ? 16oz
6lb ? 18-24oz


Q: What is the source for this numbers:
A: Wolter Pyro Tools technical documentation, although it is similar and has been verified with other tool makers.

Q: Is the range of payload weight represent minimum maximum payload?
A: No. The upper end of the range represent the maximum payload you can shoot safely, but the left represent a recommended usage minimum. If you want to put a payload smaller then the minimum then you can, but it will be cheaper to build a smaller rocket that can handle that weight.

Q: So I should never go above the maximum?
A: Well, every composition is different, and of course, if you manage to create a procedure that consistently allows you to lift a bigger payload to a safe height, then that?s great. But play safe and test many times before deciding to send your bigger rockets to the local show.

Q: Is this valid for other type of fuel or stabilizing arrangement?
A: No. This is specifically for CORE-BURNING bp composition type rockets. Any rockets that use whistle, KNO3/Sercose, end burning, fin stabilized, spin stabilized etc has different payloads. P.S. It is considered to be unsafe to put a payload on any spin stabilized rocket? but this really has nothing to do with the question

Q: What about those ?old books??
A: Hey, give me some time I don?t have all the books with me.

[Yugen-biki]

Thanks a lot again for the info!

[BurlHorse]

Just out of curiosity. How big a shell do you think you would need to get something like this?

http://cc.oulu.fi/~kempmp/johan2dd.jpg

That would Appear to be a low breaking 8 to 10" shell from the picture anyway...

Regards. Stay Green,

Bear

[chim-chim]

Q: What about those ?old books??
A: Hey, give me some time I don?t have all the books with me.

Take your time on the trivia BigG,
You've given the info we really needed, thanks.

I notice the low end of load weights are 1/4 the rockets weight description through the whole scale. This leads me to believe the scale was, in fact, determined by what the rocket could lift. Not neccesarily lift to a safe height like we need, but perhap a foot, or even just off the ground.

[Kembang Api]

BigG : I had make 3 type of rocket, 2 with BP1 mix which is 58%/32%/10%. This time I used hemp wood charcoal instead of Pine wood. The different with the 2 rockets are the end of the rocket which is fill with 20mm and 10 mm BP2 mix. The BP2 mix is just adding 5% of glutinous starch to BP1. The core is shorten from 70 mm to 60 mm.
The 3rd rocket is using the BP3 mix which is 55%/35%/10% still using hemp wood charcoal. The core is shorten to 55 mm, 10 mm of BP2 mix was used to fill up the top.
All the 3 rockets had no clay end plug for this test.

Rocket no 1 lift up for about few meters and the top part just blown away. the same thing with rocket no.2 but no lift at all. As for rocket no.3 it went so high but this time I can't measure the height, cause I did not stand far enough from the launching area. But most likely is more than 150 meter.

I had 4 more of each type of the rocket that I will test them again tomorrow and hope it will give a better result for conclusion.