Meal + metal endburners

[qwezxc12]

Greetings. Long time lurker, first time poster.

 

I wanted to share some videos I shot of a series of 1 lb. BP end-burners with various grades of added metal. I thought it might be useful to those who have not had a chance to compare different types of meal / metal side by side.

 

Specs:

.75” ID x 6” PVC body

1” thick nozzle with .1875” core

30 g of BP pressed to ~ 2.375” tall column

.75” top bulkhead

Balanced with a .25” x 48” hardwood dowel

Total weight (less stick) is ~ 105g

 

Tooling is .75” hardwood dowel rammer marked in .25” increments

Rockets were pressed in a 6-ton bottle jack press

 

Nozzle material is cat litter blended with 3% mineral oil until fine. Nozzles were drilled to .75” deep in a drill press to ensure they were plumb and centered, then hand finished with a drill bit and fingers until the swarf showed BP not clay. I normally use a .25” dia nozzle for my endburners, but I wanted a slower, more ‘showy’ lift-off, so I went with a larger nozzle for these videos.

 

Daytime height estimates for a .25" nozzle are 350-500 ft with no payload. These, I guessed ~250 ft at burn-out for the faster ones.

 

BP is standard 75:15:10 meal made with newspaper charcoal. (I use this for lift as well; 7g of pulverone will loft 40g of 3/8” pumped stars in a 1-1/4” mine to ~70 ft.)

 

All metals are 10% additional by weight

 

Here are the videos, in ascending order of spark intensity. As you can see the finer grades of aluminum combust almost wholly in the exhaust flame, in this case substantially adding to the rocket's thrust. I do not have any larger grade of aluminum other than sparkler chips / shards...and I'm betting those would stop up the nozzle = CATO

 

 

I LOVE the sound of endburners taking off!

Woo-hoo...Ti sponge rocks!

 

…enjoy.

 

 

 

Straight BP

 

5um atomized Al

 

100-350 mesh Al flitters

 

-350 mesh bright Al flake

(this one had ~almost 3" of propellant - it was leftover from another shoot)

 

200 mesh Fe

 

-30 +50 mesh granular FeTi

 

-30 +80 mesh Ti alloy flake

 

18 -30 mesh Ti sponge

[Pretty green flame]

Nice rockets.

 

FeTi and Ti sponge seem to be the best metals to add to end burners, probably because of the higher burning temperature of the metal. It also makes the fuel somewhat hotter.

[moonshot]

Yeah great post. Lots of info and good videos. I have some 4" long 3/8" ID motors that I rammed with 3mm nozzles that cato because the powders to hot. I reamed the nozzle out to 1/4" on one and tested it. No cato, so I'm going to stick one and see if it flies. I can also get very fine iron filings from the brake lathes where I work but where do you find 200 mesh screen?

[qwezxc12]

...where do you find 200 mesh screen?

I do not have a screen that fine; the iron was a freebie with an order I placed a long while ago... The mesh size is hand labeled, so who knows. It's pretty fine, though - you can just feel the particle texture in it.

[itwasntme]

Good rockets. You forgot the cheapest, easiest, and IMO most beautiful, coarse charcoal! I think the FeTi was the best tail, then again, they probably look a LOT better in person.

[cplmac]

Great job! Good idea getting them all side by side like that for easy accurate comparison. 10% is about the most you can do with a whistle rocket or you lose you whistle, I wonder what the ceiling is on a BP rocket before you lose your thrust.

[qwezxc12]

Great job! Good idea getting them all side by side like that for easy accurate comparison. 10% is about the most you can do with a whistle rocket or you lose you whistle, I wonder what the ceiling is on a BP rocket before you lose your thrust.

Thanks. I haven't played with whistle rockets yet...it's on the to-do list

 

I added 10% to accentuate the effect - I agree that it is a lot. I usually add 5% as it's plenty for a nice tail and a far more economical amount to add (especially when you're talking Ti sponge that I have to drive to pick up - Skylighter can't / won't ship it)

 

Here's an older video of a straight BP 1 lb endburner during the daytime - I was doing nozzle diameter comparisons. This one is 1/8". I estimate the height to be 300' or so and it had 26g of BP propellant + a delay to a BP marker. I press my current rocket version with about 8-10g more BP so they go a little higher.

 

Don't mind the commentary - my friends were filming for me and we couldn't keep our collective mouths shut...

 

BP endburner with 1/8" nozzle