24 replies to this topic

[tamaldas]

Hello everyone I have a plan to make rockets that can lift a higher payload ie. 250-350 gms. of spherical shell, (3"-4"dia) ,but could not make big rockets because of accidental chances of bursting before take off . I want to know safe configuration of such rockets which can carry higher payloads without any chances of bursting. I was only successful of lifting 125g shell with 22mm od rocket of core 10.5mm &ht 110mm. Is there any sight or have any one any idea of payload vs. Rocket dia including core dimentions and type of fuel reqd.? I'll be thankful if anyone helps me tamaldas

[Mortartube]

Have you tried end burneing motors? They are less complex and if they go bang occasionally, it is easier to increase the choke size or alternately add a little more charcoal to slow the reaction down. Also they don't need specialist tooling when compared to core burners. I would suggest you make some motors and put them upside down on some old scales and video the scales. That way you can freeze frame the video and see what kind of thrust you are getting.

I my experience end burners produce a more continual thrust for longer as compared to core burners which lose thrust quicker.

[rocketpro]

cleared duplicated post.

Edited by rocketpro, 29 April 2010 - 12:03 PM.

[rocketpro]

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Edited by rocketpro, 06 August 2010 - 10:00 AM.

[BrightStar]

My work horse rocket is the 1lb BP core burner. It reliably lifts 3" shells, needs only medium quality tubes, is made with cheap garden charcoal and is hand-rammed rather than pressed. I've personally found BP core-burner's easier to make reliably than end-burners, but that might be particular to me...

The details are all in the 'Rockets with Headers' thread:

http://www.pyrosocie...ts-with-headers

[Arthur Brown]

One of the Americans who used to post lots made a 12" ball shell on a rocket, It was HUGE! The "stick" was about 8 feet long, and the ball was 12 inches obviously! The rocket wasn't grossly big probably 30mm bore and 200 long.

Search some fora for the pictures! It was the subject of a whole topic and there was a vid of it flying IIRC.

HOWEVER please remember that that poster/builder had the safety spaces to fire something that size. In the UK you may NOT have. I think he was able to shoot it on a 10 MILE square of scrub so no risk from a cato OR the STICK (plank!) coming down to cause damage.

A 3" ball shell used to be available in the UK as a cat3 firework hence be a shell burst on the retail market. Since the regs change fewer big rockets are 1.4 and cat3.

Beyond 3" there is nothing to commend a scale stick coming back down from a rocket, when you could have a shell breaking into less damaging shrapnel (floaty bits of strawboard!).

Edited by Arthur Brown, 29 April 2010 - 01:56 PM.

[rocketpro]

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Edited by rocketpro, 06 August 2010 - 10:01 AM.

[tamaldas]

My work horse rocket is the 1lb BP core burner. It reliably lifts 3" shells, needs only medium quality tubes, is made with cheap garden charcoal and is hand-rammed rather than pressed. I've personally found BP core-burner's easier to make reliably than end-burners, but that might be particular to me...

The details are all in the 'Rockets with Headers' thread:

http://www.pyrosocie...ts-with-headers

Dear Brightstar Just I have gone through the " Rocket anf header" topic discussion but to be honest there are some confusions still about the core dimention & od of the tooling. Being a mechanical engineer I'll turn it in my lathe if you can send an Engineering drawing (elevation) in two dimention of the whole tooling. I had collected some information fm 'rocket tool sketcher' in flashnet but I need some reliable one from a man who has successfully lifted that kind of payload. Please help me if you can. Thanks
tamaldas

[tamaldas]

ame='rocketpro' date='29 April 2010 - 12:52 PM' timestamp='1272541941' post='64853']

If you`re going the cored motor route, Pudi has an excellent programme for motor design right here on the forum. To safely lift that sort of weight you will need to go 7/8" bore minimum, preferably 1"

Needless to say you will need a sturdy press and some strong tubes.

If you need any help PM me and i`ll take you through the whole process, so you get good results from the start.


Incidentally, there is always a chance of motors bursting, so a good safety distance is required.

Dear Rocketpro please send me the drawing with dimentions in CGS system of the core & other ramming tools and also the type of fuels to be used with proportions of chemicals if you have successfully lifted above 200gm shell. In our area ue use sticks of jute tree to attach with rockets which are very much light in weight but10-12 feet long and have sufficient strength tohold the load and being lighter in weight less accidental risk is there to fall on ground. Thanks tamaldas

[Arthur Brown]

You will find that no two people have the same ideas of perfect! Also No two people prepare their comps the same way or get the same effect from a comp. Sometimes it's simply ingredient mesh size distribution, sometimes other things. Regardless, someone's design may not be perfect for you.

[dr thrust]

hmm for a 4" shell you'll have to think big, a 3lb motor
propellant " urbanski 59,31,10, milled two hours riced with 3% vaseline, this is optional but i prefer a softer grain.
quite a big rocket a 3 lb'er usually 10" long! so it needs a cool fuel
the basic dimensions for bp core burner motors are,

the case length should be 10 times the case id

the spindle length should be 8 times the case id

spindle width at base to form nozzle should be 1/3rd case id,

but Ive seen spindle widths with half case id tapering to 1/4 case id at top of spindle
with these basic dimensions you can turn your tooling
these 3lb motors are large so factor in you'll be needing a very large open space

Edited by chris m, 29 April 2010 - 10:59 PM.

[tamaldas]

hmm for a 4" shell you'll have to think big, a 3lb motor
propellant " urbanski 59,31,10, milled two hours riced with 3% vaseline, this is optional but i prefer a softer grain.
quite a big rocket a 3 lb'er usually 10" long! so it needs a cool fuel
the basic dimensions for bp core burner motors are,

the case length should be 10 times the case id

the spindle length should be 8 times the case id

spindle width at base to form nozzle should be 1/3rd case id,

but Ive seen spindle widths with half case id tapering to 1/4 case id at top of spindle
with these basic dimensions you can turn your tooling
these 3lb motors are large so factor in you'll be needing a very large open space

HI Chris I have finally made two of length 10'' * 1". The core dimensions are almost same as you have advised with slightly difference , I have kept core length 7.5" , that to withstand the force of initial fuel burn. The Ist one without header have been successfully launched, now I have to launch the 2nd one with a header of 200gm. For that I have to drive 10 miles to a farmhouse for safety.Ill give you the feesback lateron.Anyway thanks for the configuration tamaldas

[Arthur Brown]

http://www.amateurpy...big-ass-rocket/

Is this big enough!

[Arthur Brown]

Or this.... http://www.theskypainters.com/ scroll down for link and pic!

[seymour]

Tamaldas, I apologise for hijacking your thread, but I can't help but reply to Arthur with a post of some links of some crazy skyrockets from Thailand...







cato...