[Pyromaster2003]

How about a competition for the most powerful small 1/4 inch ID rockets?

Dont know how good this is for a 1/4 inch rocket but i got over a 100grams of thrust from one the other day, trying to carry some payloads with these things. If they can be made to carry a 1.5 inch shell it would be spot on! I had one carry a 1 inch shell a few months ago but havnt tried it since - posted some where about me proving it could be done so im trying to reproduce this again. Heres some vids of a few 1/4 inch drivers i made:

http://youtube.com/watch?v=6jBcblZp-C0

This post has been edited by Pyromaster2003: 13 May 2007 - 09:43 AM

[aquarius]

Looks quite good to me.
What are the specs?
(Fuel, spindle length and diam. etc)

[Pyromaster2003]

Thanks fuel was just straight meal for the rockets on the scales and the rockets that flew just had a bit of ti added. They are all end burners, so no spindle i just drilled the choke out. The choke was 2mm on the ones that flew and the ones on the scales had chokes of 1mm, 2mm, 3mm, no choke and a 2mm choke with hand pressed meal, ended up exploding and turned the hard walled tube to shreds - quite surprising for black powder!
Want to experiment with core burners coz these will give a lot more thrust its just finding the time to do it will need to make up a little spindle for these.

Good thing about these small rockets is you can fill the tube to the top with comp, ram it down with 2 decent blows and by the time you have done this 6 times the tube is full of comp then its just ramming the clay end and drilling, takes about 5 mins total...will be good if i can perfect these to carry 1.5 inch shells would look great firing 10 or so at once with different effect shells on top.

[aquarius]

I have made some quite successful 12 and 15 mm ID core burners.
My 15 mm lifted 200 grams of lead deadweight to a fair height.
The 12 mm lifts close to 100 grams (to) high.

So I might try for a smaller driver, and 1/4 inch is 0.63 cm.
Will try a 7 mm ID coreburner with a 3 mm nozzle opening, hand rammed.
That's close to the ratio I have been using on my other drivers.

[Pyromaster2003]

Sounds good let me know how you get on im very interested in these little rockets now, their so cheap and quick to make look good aswel.

[wyattp4007]

Hi all! After seeing this thread I thought I'd give it a try, I have many 1/4" tubes I've been using for bottle rockets but never actually recorded the thrust of them, so I figured what the hey, let's see what I've got.

I just got done making a new spindle and rammer for 1/4" ID rockets the other day and tested a few out on my scale. The rocket spec's are:

Total Length - 2"
ID - 1/4"
OD - .335"
Fuel - Meal powder 1g
Core diameter/Nozzle Throat - .95"
Core length - 1/2"
Nozzle - 40 degree convergent to 10 degree divergent.

Total Engine Weight - 2.35g (no load)
Peak Thrust - 36.7g
Total burn length - 1 second

Thrust to weight ratio - 15.6

Considering these are spiral wound tubes with a very thin wall I was surprised how much thrust they gave without exploding, the thin wall restricts maximum performance I can get from them without blowing them up. I really need better tubes.

With just a 250mg salute header I've gotten a couple of these rockets to about 350 feet! I have a video of the static scale test for the 36.7g rocket if you want me to post it.

I'd like to know the weight of the rockets you guys are making as well, I try for the best thrust to weight as possible.

[Pyromaster2003]

Havnt weighed the rockets iv made but i know the 2 inch long x 1/4 inch ID tube i use with a thick wall weighs 2 grams and im guessing the bp and clay will make the total somewhere around 4grams. Strong parallel tubes are best for rockets coz they are a lot stronger.

Wouldnt mind watching the vid have you got it on U Tube?? 37 grams of thrust aint too bag but think a shell header is out of the question, with the right tube, a hotter comp and the right choke i think 150 and possibly 200grams of thrust is possible. Mine had no core and just meal with a 2mm choke and got 100g so with a core i reckon 150-200g is possible??

Trying some more of these small rockets today if i get chance, this time 4 inch long with a half gram ti flash header, hopefully these will get to a decent height.

[dr thrust]

these look great fun, and i,am going to build a few but would a perc based bp fuel give more thrust in a small end burner?, also it would be great to recreate the old 1/4" whistling moon travelers of old , as 3lb,ers are a bit to big for the garden

This post has been edited by chris m: 23 March 2008 - 02:37 PM