Hi all, We had another great day this weekend launching rockets at the NSWRA launch meet. There was a unique opportunity to launch during fog to see if we...
8361
Henning Negaard Torst...
henning_tors...
Jun 2, 2008 5:03 am
... Wow! Great stuff! Too bad about the crash, but I have to admit I LOLed on the "off nominal trajectory". Henning...
8362
suwan pitaksintorn
suwanpi
Jun 3, 2008 1:31 am
Great work George. I really appreciat both flight video and music. Suwan ... From: George Katz <air.command@...> Subject: [water-rockets] New...
8363
George Katz
air.command
Jun 3, 2008 2:19 am
I think the problem with the last flight was a basic stability issue. We reviewed the video frame by frame, and it looked like the most plausible explanation....
8364
Trevor Hannam
trevor_mixie
Jun 3, 2008 7:39 am
Well done George – Some height you got. Damn good footage of the flights and what a pit about that rocket crashing. All that work gone up in a heap. I am ...
8365
Daniel Kirk
dk54321
Jun 4, 2008 2:55 pm
Looking through the archives, I saw several members mention using RockSim to calculat CP and/or CG. RockSim is my simulator of choice for pyro rockets. It has...
8366
George Katz
air.command
Jun 5, 2008 1:05 am
Hi Daniel, That would be very cool to try with RockSim. It would be worth trialing to see how well RockSim can predict altitude compared to actual flight. I...
8367
Clifford Heath
clifford_heath4
Jun 5, 2008 1:47 am
The thrust curve is phenomenally complicated, but if you figure several factors you should be able to get a good approximation. First up, the total energy in...
8368
George Katz
air.command
Jun 5, 2008 2:52 am
<snip> There's a point during the thrust of every good WR where the exhaust water is stationary - before that it's moving downward, later it's departing...
8369
Jon Mehlferber
jmehlferber
Jun 5, 2008 3:44 am
I have used RockSim, but only to figure out the drag coefficient (Cd) of different bottle shapes/combinations so that info fed into WR sims like Clifford's are...
8370
Clifford Heath
clifford_heath4
Jun 5, 2008 4:57 am
... For optimum efficiency, the available energy is converted to the maximum amount of kinetic energy in the rocket (obvious). That means that anything else so...
8371
George Katz
air.command
Jun 5, 2008 5:17 am
... I guess the only two options here would be to either decrease the volume of the pressure chamber as the rocket accelerates in order to increase the...
8372
Mike Passerotti
mikepasserotti
Jun 5, 2008 1:43 pm
The volume of the chamber does decrease, at least a little. The soda bottle is elastic and stores some energy there returning it as the pressure starts to...
8373
Daniel Kirk
dk54321
Jun 5, 2008 6:08 pm
... Maybe I should cross-post this to the microhybrids group: http://groups.yahoo.com/group/microhybrids/ They fly pyro rockets with solid fuels and liquid N2O...
8374
Clifford Heath
clifford_heath4
Jun 5, 2008 10:25 pm
... Water rocket motors have different thrust curves when run stationary vs flying, due to the effect on nozzle pressure of lifting the water. It would still...
8375
Paul Grosse
jflinden
Jun 6, 2008 12:42 am
If someone wants to quantify it... The extension of the bottle is going to be pretty much the same regardless of whether there is water or air (or both) in it...
8376
George Katz
air.command
Jun 6, 2008 1:10 am
Cliff, as you mentioned that varying the nozzle size in flight would not help, and since increasing the air pressure in flight is a also little more difficult,...
8377
richardhammondslabrats
richardhammo...
Jun 6, 2008 1:35 pm
Dear Water Rocket Enthusiasts and Experts, Production has begun on a major new series for the Children's BBC – `Richard Hammond's Lab Rats'. Every show will...
8378
Mike Passerotti
mikepasserotti
Jun 6, 2008 1:37 pm
This is a legit request. I corresponded with Any myself. Please respond directly to Andy and then let the rest of us know if you'll participate. Mike...
8379
Gary Dargan
dargang
Jun 7, 2008 12:04 am
If you change the density of the fluid I suspect that it will be a case of "what you gain on the swings you lose on the roundabout". You will still have to...
8380
Trevor Hannam
trevor_mixie
Jun 7, 2008 11:28 am
Hi Mike Got that Email as well . Looks as if we might have all got it. Pity we don’t live near London Trev From: water-rockets@yahoogroups.com...
8381
Trevor Hannam
trevor_mixie
Jun 7, 2008 11:45 am
Hi Gazza/George Let me get this straight – Are we looking for a thrust that is constant whether it be air or water. Trying to hold a longer thrust time yet...
8382
David G Leatham
dave698221
Jun 8, 2008 1:50 am
ya how bout a free ticket from- to everwhere/ i got a few wrocket ready to go. HeHe \ have wrocket/ will travel dl ... From: "Trevor Hannam"...
8383
Paul Grosse
jflinden
Jun 8, 2008 10:52 am
... <snip> I'm in. -- Regards, Paul Grosse Home Pages http://www.grosse.is-a-geek.com/ Project Pitcher Plant http://www.fresh.files2.serveftp.net/ Water...
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Mike Passerotti
mikepasserotti
Jun 9, 2008 10:31 pm
There is a mass flow controller that also regulates flow independant of the pressure or temperature variations. I don't know what kind of valve it uses, but...
8385
Daniel Kirk
dk54321
Jun 12, 2008 3:45 am
My rocket was launching fine, but as soon as the water ran out, it would go unstable, tumble wildly, and decelerate abruptly. I needed to add nose weight for...
8386
George Katz
air.command
Jun 12, 2008 6:22 am
Great to hear you had some success there Daniel! :) Well done. Using the water as nose weight is a good idea too. We've used the technique a few times and...
8387
George Katz
air.command
Jun 13, 2008 12:35 am
So what do you guys put on your checklist when going out launching? I'll start the ball rolling with ours: Always Bring * Silicone Grease (for nozzles and...
8388
Trevor Hannam
trevor_mixie
Jun 13, 2008 10:40 am
Compressor, water. Pliers and spanners, sunscreen, warm clothing,the wife and kids and friends, lunch,rockets, fins, paper, carboard, 3mm sheet balsa, glue –...
8389
Trevor Hannam
trevor_mixie
Jun 13, 2008 10:48 am
Whoops! mustn’t forget the spare bottles From: water-rockets@yahoogroups.com [mailto:water-rockets@yahoogroups.com] On Behalf Of Trevor Hannam Sent: Friday,...
