14 replies to this topic

[willd]

How safe is it to ram a bp rocket with a mallet.
Just wondering after having seen something on chaz's site saying someone maneged to blow some fingers off while ramming a bp rocket.
If it is dangerous are there any precations i should be taking to save my fingers

[Richard H]

Black powder is a relatively safe composition to ram or press. The risks increase when you start adding metal powders such as sponge titanium or use sparking (ferrous) tooling. When ramming or pressing any composition always wear thick gloves, long sleeved cotton shirt, and safety glasses.

Always use non-ferrous (e.g. brass or aluminium) tooling.

Always ram in a location away from other persons, mixed compositions, or flammable articles. When pressing a composition always use a blast screen.

[dfk]

There is no 'safe' in pyrotechnics, Everything is potentially dangerous.
If your not comfortable with your procedures don't do it.


On the other hand this along with pressing is how rockets are made and have been made for a while. There are lots of precautions to be taken and I would say you should find out more before proceeding.

I remember reading about a case of accidental ignition. I don't remember if it was a hypothetical scenario or if it was real, but it made sense. It said that in the case of accidental ignition, the rammer would (or did) shoot out of the rocket casing under the pressure of the initial ignition, then would then just burn as a tube of pressed powder would. The pressed powder doesn't have enough surface area to burn quick enough to build the amount of pressure it would take to 'explode'.

Take this how you want, I don't think there's any study on the subject but it sounds
believable. I don't know if this makes anyone feel 'safer' but I guess you could add "don't hang your head over the tube of black powder you are hitting with a hammer"
as a precautionary measure.

[maxman]

Is it an acceptable practice to RAM a BP rocket with added Titanium?
I'm just putting a Skylighter order together but may leave off the Titanium if I'm likely to get problems from ramming.
I read somewhere (Dan Williams site I think) to use spherical Titanium for a rocket tail but that product seems to have been removed from Skylighters site. Dose anyone know what other Titanium from there site would be best?

Thanks

[BigG]

Is it an acceptable practice to RAM a BP rocket with added Titanium?
I'm just putting a Skylighter order together but may leave off the Titanium if I'm likely to get problems from ramming.
I read somewhere (Dan Williams site I think) to use spherical Titanium for a rocket tail but that product seems to have been removed from Skylighters site. Dose anyone know what other Titanium from there site would be best?

Thanks

No, it is not an acceptable practice to ram ANY composition containing titanium - even if it is in sponge format.

Use a press - keep your titanium content under 8%.

[alany]

Basically, no.

However I personally take the risk with spherical Titanium all the time. I'd never risk it with flake or sponge, and never drill into it. Flake makes a very dense tail, but the sparks are shorter lived than with spherical in my experence.

[Kembang Api]

Just to share some of the experience in making BP rockets. I had been doing both ramming as well as pressing BP rockets (58/32/10 and 75/15/10) they are very safe so far. But making BP rocket by ramming would not give you a very consistence results, I would recommend to press it with a good hydraulic press.

Big G had recommended me to press it to 8800 psi, but because of my hand made tube I manage to press it only 3000 psi. With this pressure I had never had any failure so far out of the 56 rockets that was produce. Last week I attached a 2 inches shell (47 grams). 10 of the rockets were successful.

Thanks a lot to BigG for the advices.

[sasman]

When talking about Pressure you must remember that you should use pounds force on the rammer? NOT psi??.
...I pressed my rockets at about 500 psi on my hydraulic press .500 psi on my press equals about 6000 lbs force on the rammer ..
.....to work out the force on the rammer you must know the diameter of the ram on your press ...my ram was 6.5 cm..in diameter..So pye R squared= surface area

3.142 x(radius2)32.5mmX32.5mm=33.18 cm Surface area(of my ram)
...... Now you need to know the diameter of ram on your rocket or whatever your pressing im using 3/4 ram (19mm) So...

3.142 x(radius2)9.5 X 9.5mm=2.83 cm Surface area(on rocket ram)
So if you want 8000 lbs force on your ram?
You need to do the math
.... 2.83cm X 8000lbs = 22640 lbs divide this by surface area of your ram 22640 divide by 33.18cm(ram surface area)=682 psi on the gauge ..
.
So as you can see even though i had` only 682psi on the gauge the actual force on the ram was 8000 lbs!.
....So Kembang api if you pressed at 3000lbs do you know what your rams surface area is? i Guess pressing with a 4 or a 5 ton press you would need about 3000 psi on your gauge what tonnage is your press?...

[BigG]

First sasman - When I said 8800psi, I meant psi. Good source for calculation thorey is on http://www.wolterpyr...tips/rppcf.html

Second, the discussion was specific to Whistle Mix rockets. You do not need such high pressure on BP. The pressure on Whistle is to avoid explosion of the rocket.

Third, I'm not great in rockets , and I'm sure I said somewhere that it's not my cup of tea. Shoot about seven recently - they all lifted with no blow through, but three of them hit the ground before the header ignited. Practice makes perfect - and only lots of tries get you to have perfect flight every time. Even the biggest experts ? with well documented procedures and endless retries - get it wrong from time to time - Especially when trying new type of device or having to switch source of materials.

[Kembang Api]

BigG : I was not aware that you are mentioning the psif of 8800 were for whistle rocket. I presume it was for BP rocket. Anyway I stop the press as soon as I noticed my home made paper tube start getting press down ( I have a steel sleeve to protect the tube during the press)

Sasman: Thank you for the calculation. My rocket's size is 20 mm inner diameter and my old hydraulic press come with an analog gauge in MPa. What should be my reading at the final press? Thank you for the help.

[robfir]

Begginner Question:
Is there no risk of BP igniting in a press?
Im worried that if i pressed with a jack at the bottom, a stainless steel tube with the BP in in the middle, and a 12 ton "roof" to stop the jack pushing the powder out the top, then it would surely explode (ie. as diesel in a diesel engine does) and because the "weakest" confinement i mention above is a stainless steel tube, it would be catastrophic? Sorry if its obvious, I just cant get my head round how i can make BP pressing safe?

[Richard H]

It is generally quite safe to press BP without any added metals etc. I would however recommend you use a PVC tube with pipe clamps rather than steel. Make sure you use a blast screen between you and the press.

[robfir]

So it should be safe to press this comp: 75% saltpetre + 12% sulphur + 13% wilow charcoal? should i leave in the 8% water from the ballmill or dry it before pressing?

[RegimentalPyro]

Safe is a comparative term. There's always risk and it's important to remember that. With that said, that particular comp has a very low risk. Especially dampened as outlined.

[adamw]

Press BP all you want! (or can!). What occurs in an internal combustion engine is very different from pressing a rocket motor!!!