61 replies to this topic

[dr thrust]

i think your flogging a dead horse here with the sodium benzo, at this time of year there just to much moisture in the air, a nice hot sunny day yes.
out of interest when im milling my pot benzo it was clumping in the mill and coffee grinder but now i add the fe to the pot benzo then coffee grind,( dedicated coffee grinder, its real messy) then mill for two hours and it comes out nice and fine

Edited by chris m, 08 February 2009 - 08:10 PM.

[Vic]

Guess you could be right there Chris with a Relative humidity of 98 here, the upside though is less static build up.

[dr thrust]

all is not lost!, you can make some nice whistle fountains with it! i made a 1" id titanium whistle fan fountain for the 5th and it went down well with the crowd

[knackers]

No probs with humidity here, officially we just had 47.7 C, but on my scientific thermometer, ( in the shade 3' off the ground under a tree ) it was 49 C , i think thats about 130 odd F on your scale

too bloody hot to go out netherlone press any whistle



Edit:-, i read in one of the posts a reference to a nozzle,, as far as i understand with whistle rockets , they are not only nozzle less but there must be some empty tube at the flame end so as to accomadate a reverberation chamber to get a whistle at take off or the whistle won't happen untill there is enough empty tube to reverb, which with murphys law will be at the end

Edited by phill 63, 09 February 2009 - 10:11 AM.

[Vic]

Just got back from a jolly jaunt, through floods, sleet and freezing cold, and I forgot to put on the wellies but apart from that the whistle sound is back but thrust still down, the first being 3” and the second 4” length tube hit the deck. Here's the footage.

i found the 64/32/1/3 faster than the 76/23/1/2 !???

Think you could be right. Definitely no more power in the 76/32/1/3 if not less than the 64/32/1/3 mix.

The things we do for our art


Vic.

Edited by fflach, 09 February 2009 - 08:00 PM.

[ExplosiveCoek]

*BANG* through your neighbor's roof hehe

[dr thrust]

according to a book i have on the subject, for a "raspy" rocket 70/30/1/3 is the optimum mix for sodium benzoate whistle, the, 76,23,1,3 is a sodium salicylate whistle formula, and the 64/32/1/3 is a salicylate whistle that works well if the salicylate is not available and so substituted with pot benzoate. nice job on the rockets! and great to see a bit of video, bbbrrrrrr cold .
how far are you going above the spindle?, theres just no thrust after the core has gone and a large whistle delay grain will come back to earth. also more thrust less whistle noise , lower thrust ,yes youve guessed it more whistle noise.

Edited by chris m, 09 February 2009 - 09:06 PM.

[Vic]

how far are you going above the spindle?

On the first there was 1” of delay above the spindle and on the second 2” of delay

Going to try backing off on pressing pressure a bit as the tubes were showing signs of swelling even with two layers of sleeving and well clamped to see if that makes a difference to performance.

So all in all whistle mix like black powder is infinitely variable mix to give a desired outcome, you can well confine average BP and get a reasonable report, as opposed to fast Bp with medium confinement, so you could have medium fast whistle mix as long as core length and diameter is optimised for the burn rate, but I suppose there’s going to be a trade off with more fuel weight for given amount of thrust.

Edited by fflach, 12 February 2009 - 12:38 AM.

[dr thrust]

agreed, look at altering your tooling, ive made great rockets with very basic tooling indeed( ali rod stuck in a block of wood) say even a slightly longer spindle 5mm longer than what you are using at the moment will make a difference, and try cutting your delay grain down to 1/2" and see how that goes

[Vic]

ive made great rockets with very basic tooling indeed

Something like this maybe, made this about 2 years ago with no more than a drill, file and emery cloth and it flew first time



Here’s the movie

Edited by fflach, 12 February 2009 - 11:23 PM.

[dr thrust]

yeah cheapo tooling thats the ticket, and nice first whistle rocket, also instead of vaseline try binding with mineral oil, in an acetone carrier, it has a cleaner burn and not as messy mixing

[Vic]

instead of vaseline try binding with mineral oil, in an acetone carrier

I don’t think I will go the mineral oil way at the mo, have heard varying views on it’s performance going to stick with vaseline and thinners otherwise I may end up with long drying times and possibly chuffing

I think most of my problems I had were down to the last benzoate I had, it was coarse mesh compared to the first batch which I had from the same supplier. The KClO4 was really fine but that has clumped up with storage. I dry this as well as the benzoate in a 100c oven separately not together and mill the perchlorate for ten minutes

[Vic]

Made the leap to high powered long cored whistle rockets but they are nothing like as powerful as the awesome whistle bp hybrid rockets which I tested some time back.

Compare the 1lb whistle with a 1lb hybrid with a ballast 4” dummy ball shell both made with the same tooling

Latest whistle:

hybrid:

[dr thrust]

nice job on the hybrid, i presume the motor has a nozzle?, anyway back to the old Vaseline v mineral oil thing , ive found Vaseline makes really smoky motors, and mineral oil doesn't bind my bp nozzless motors very well, on opening a rocket motor for inspection i found i could pull apart the increments quite easily, as apposed to the Vaseline motor which was a solid mass.
well the other day i was cooking up a batch of iron filings for a Clarke's fountain and the instruction called for them to be coated in paraffin wax, also the benonite nozzle of the fountain called for the inclusion of wax dissolved in thinners to make a tougher nozzle.
where's chris going with this, whats he on about?
this got me thinking could 2%paraffin wax dissolved in a carrier be a third option for binding motors, its the only one out of the three design to burn cleanly ( candles!), oh i want four candles

Edited by chris m, 15 April 2009 - 04:41 PM.

[Sambo]

Has anyone got a supplier for copper oxychloride? or a good way to make it?
I've read up on two ways but there’s no feedback to what is the best.

Cheers
Sam