Rocket competition submission

[al93535]

This is another BP end burner. It has a header that weighs in at 86.4 grams, the total rocket weight is 144.6 grams. The header is 6 whistles to Ti reports.

 

Prefiring pic:

 

http://img.photobucket.com/albums/v242/al9...cketWinsert.jpg

 

Video:

 

http://www.apcforum.net/files/whistlesreportrocket.wmv

[FrKoNaLeaSh1010]

Do you mind sharing the size of motor and method of preparing the propellant and ratio of bp you used. Any end burning BP rocket that can lift a header more than it weighs must be a very nice work horse rocket. and I would assume those whistle to Ti report would be built along a bottle rocket type design? That would be a very nice effect for a cannister shell or of course as shown.....a rocket header. Very nice design and rocket.

[al93535]

Absolutely,

 

I use ball milled black powder 75/15/10, made from weeping willow charcoal. The motors are 5/8" ID by 4" long, with a wall of 3/32". I ram a 1/2" conical plug then the pure BP, then a 3/8" top clay plug. I drill out a 1/8" nozzle, and on this particulat rocket I made a 1/4" core. I normally do not use any core, but I had a heavier header this time. My engines normally weigh around 40 grams.

 

The whistles are made by rolling a 3/8" tube 2.5" long. I press a clay plug recessed into the tube about 1/4". Next I press a 3/4" colum of whistle. Flip the thing over, drill a passfire hole, fill with flash and plug.

[dragonman586]

What do you use to press the whistle? Can you use hand pressure for tubes that small or would you need a press?

[al93535]

I don't think you can properly press the whistle with hand pressure. I use an arbor press. These are realatively cheap, are easy to use, and I press faster then I can ram.

[pyro4life]

When you say a 1/4 inch core, you obviously mean a 1/8th inch diam core that goes into the grain 1/4inch ? Briliant rocket and header aswel nice work with all your rockets. You say you use a conical clay plug, can you take a picture of the rammer you use to make the conical plug and post it? Thanks a lot

[frogy]

A conical plug means it's shaped at 30 degrees on the outside (the outer nozzle goes in at 30 degrees) and sloped to 60 degrees on the inside...

 

This shape pattern provides optimal compression of the gases so they provide 10-20% more thrust than just a flat nozzle

 

Here's a picture of my rather crappy homemade wooden tooling, but you can see the bottom of the spindle is about 30 degrees and the nozzle former about 60 degrees

 

http://img221.imageshack.us/img221/5851/toolingiv4.th.jpg

 

The nozzle diameter was 1/8th an inch and the core was 1/4 inch long... your correct

[cplmac]

Another one I missed, sorry al I'm not ignoring you. Beautiful head, I love Ti whistle to report headers.

[pyro4life]

Ye i know the reason for the conical end, usually used in end burning rockets so the gasses dont burn through the tube just above the nozzle.

 

The problem is/was i use very heavy walled (4.5mm thick) 3/4 inch id commercial, convolute tubes and the gasses just burnt though the tube above the nozzle. I made the end of my rammer conical but this still never worked. Anyway i made the cone shape a bit more 'steep' so there was more clay up the inner wall of the tube and fired a couple of great end burners just after i posted on here. So problem solved.

 

Was just interested in seeing the shape of cone that was being used in al's end burning type rockets as they are what i make..

[Mumbles]

Al has commercial tooling. I do believe it is 45 degrees on the inside and 30 degrees on the outside.

[pyro4life]

Cheers. Will be metal tooling then. I got mine sorted now put a 45 degree cone on the end last night seems to work ok.

[frogy]

You want 30 degrees on the spindle and 45-60 degrees on the nozzle drift (rammer)

[Mumbles]

I would think anything more than 45 degrees on the drift would be overkill. 45 degrees has the highest amount of compression of gas(higher temps for higher pressure), and nozzle velocity.