248 replies to this topic

[Maineiac]

Nice! I love the way the little 2 oz motors zip out of the pipe. That blue looks very nice as well. Is that #1 or #2 (oxide vs. carbonate)? How did you prime the stars?

Edited by Maineiac, 22 November 2005 - 09:48 PM.

[raiderzone]

Nice! I love the way the little 2 oz motors zip out of the pipe. That blue looks very nice as well. Is that #1 or #2 (oxide vs. carbonate)? How did you prime the stars?

Thanks Maineiac. I take that as a compliment from someone that works with Tom R. On the West Side here, I try to pick Steve Majdali's brain whenever I go to his house to buy tools . He's a very nice fellow and very down to earth. Anyways, please see notes below regarding your questions:

Blue Star Formula in vid:
Conkling #1 (Bought the Copper Oxide II from a local Clay Supply).

Primed With:
Universal Meal Prime from Passfire Shared Area:
Potassium Nitrate 20
Charcoal Airfloat 5
Sulfur 3
Dextrin 2
Notes:
I've found this prime to work really well with most formulas, including Blesser White Strobe. This has been passed around on the PML for years.

I've been using screened 7/3/1 fuel for the smaller bore core burners. I know 6/3/1 works fine, but 7/3/1 turns them into mini hot rods with better lifting capability.

[Maineiac]

I'll have to give that blue a try. If the video is true to life then it seems better than the Shimizu B-70 (to my blind eyes anyway). I'll run a mess through the plate and see how they work.
I agree with you on the smaller motors. I use 15/3/2 meal in my 2oz just because they are sooo fast. With a light header they almost travel too far! Never any problems as long as they are well rammed. Good for a quick fix when the bigger motors would be too obnoxious.

[sizzle]

I'm currently working on a 3" Ball Head rocket as a finale peice for my Christmas Ever display, I have placed my stars around the edge of the shell but do I need a layer of tissue seperating the KP burst from the stars or do I just place it in the centre, also how much KP would anyone reccomend for a 3", I would experiment but I only have one of these shells to spare.

[Maineiac]

What are you putting the KP on? KP is a bit weak for smaller shells from what I've seen. A more typical break for 3" balls has been to coat corn cob with meal powder and then place 4-6 grams of benzoate whistle loose in the shell. No need for a flash bag to hold the whistle either. Experiments have shown that the breaks turn sloppy when you include one. As for seperating the stars from the break charge...its never been required using the above method. A sample break can be seen here 3" Shell Break but you'll need a Pyroreview login/pass.

[Pretty green flames]

@Sizzle
I personally would go with BP covered grass seeds. I've used this in my 2" and 1.5" shells with great succes. You can get a very symetrical break if your pasting is good.

One thing that's good about only nitrate avaliability (sp?) is that you can make the best of your resorces. Just use BP on grass seeds and it'll work good.

In other news i made a 4cm ball shell header rocket.




Will try to light it tonight if it stops snowing.

[fishy1]

@Sizzle
I personally would go with BP covered grass seeds. I've used this in my 2" and 1.5" shells with great succes. You can get a very symetrical break if your pasting is good.

One thing that's good about only nitrate avaliability (sp?) is that you can make the best of your resorces. Just use BP on grass seeds and it'll work good.

In other news i made a 4cm ball shell header rocket.


Will try to light it tonight if it stops snowing.

nice looking rocket, will you video it?

[Pretty green flames]

I will try

[JamesH]

Heres a few photos and a video clip of a 1.75" ball shell rocket i fired last night.

http://i11.photobuck...22/a34a2656.jpg
http://i11.photobuck...22/cb2ebe0f.jpg

http://media.putfile...-shell-rocket10

The rocket fired was identical to the one in the photos, except the rising tail on the heading was not included.
The rocket was a 1/2" I.D. 4oz BP endburner and the shell weighed in at 39g.
As can be seen in the video, the heading burst upwards, due to the momentum imparted to the stars by the still fast moving rocket.
Simply adding delay to the motor would not be a solution as the rocket was already high enough when the shell burst (a bit too high up for my liking). To improve these rockets i will try decreasing the amount of propellant by 1/3rd and add a delay of about 1.5 - 2 seconds.

Today, I tested a motor identical to the one used in the video, but carrying an 80g payload. The motor performed very well with this heavier payload, the lift was a bit slower, which was good since i thought the acceleration on the other rocket was a bit too high. A 2 - 3 second delay would be about right for the 80g payload since it coasted for a few seconds after burn-out. The apogee seemed just right for a decent heading.

So the other option is to use a heavier payload in conjunction with a delay.

Edited by JamesH, 13 December 2005 - 05:54 PM.

[adamw]

Moved (to the 'Pyro' side)

[Frozentech]

Heres a few photos and a video clip of a 1.75" ball shell rocket i fired last night.

http://i11.photobuck...22/a34a2656.jpg
http://i11.photobuck...22/cb2ebe0f.jpg

http://media.putfile...-shell-rocket10

The rocket fired was identical to the one in the photos, except the rising tail on the heading was not included.
The rocket was a 1/2" I.D. 4oz BP endburner and the shell weighed in at 39g.
As can be seen in the video, the heading burst upwards, due to the momentum imparted to the stars by the still fast moving rocket.
Simply adding delay to the motor would not be a solution as the rocket was already high enough when the shell burst (a bit too high up for my liking). To improve these rockets i will try decreasing the amount of propellant by 1/3rd and add a delay of about 1.5 - 2 seconds.

Today, I tested a motor identical to the one used in the video, but carrying an 80g payload. The motor performed very well with this heavier payload, the lift was a bit slower, which was good since i thought the acceleration on the other rocket was a bit too high. A 2 - 3 second delay would be about right for the 80g payload since it coasted for a few seconds after burn-out. The apogee seemed just right for a decent heading.

So the other option is to use a heavier payload in conjunction with a delay.

Nice. Have you considered moderating burn rate with Sodium Bicarbonate or perhaps lampblack ? Even adding an additional bit of coarser mesh charcoal could slow it up.

[Yugen-biki]

JamesH

I had the same problem with my 1lb core burning rockets. But as the fuel in a coreburner is consumed faster, the shell exploded very soon after take off. I solved his problem with a dealy composition found in Lancaster page 275. It consists of BP with extra KNO3 and sulfur. I use 1cm of delay pressed in the top of the rocket. This gives a good delay and no time fuse on the header is needed.

[Mumbles]

Does the delay itself shoot sparks into the shell and cause it to go off, or is there a passfire of quickmatch or something like that that takes fire from the delay to in turn set off the shell? Personally, I would feel much safer with a passfire, but I was just wondering on how you did this.

[Yugen-biki]

Instead of a time fuse in the shell, I use a black match. The delay and black match are closely put together when the shell is glued on the rocket.

[al93535]

I am pretty sure I downloaded this rocket video here some time ago. I would really like help figuring out who's rocket this is! I love the glitter and would like to know the formula!

http://rapidshare.de...r_0001.wmv.html