Soda Bottle rocket taken to the next level!

[steve]

I've been doing a lot of experimenting with these rockets over the past few days. One of the more interesting experiments I tried was linking two bottles together, but I underestimated the amount of pressure produced (I'd estimate around 100 psi?) and the concequence of this was rather spectacular- (Watch the video!!!) It didn't imediately light so I picked it up to see what the problem was and noticed that it was still on fire. I had just enough time to curse before it blew! No one was hurt and we were all laughing hysterically for the next 5 minutes.

Anyway I have temporarilly abandoned that idea, but I have a better one- A machined rocket nozzle. It took a few hours to make but it came out really nice and there is a noticible improvement in the rockets performance and stability (the throat diameter is 1/8 inch). even without fins it will fly fairly straight now whereas before (with the crude hole-in-bottlecap nozzle) it would start to tumble imediately. One of the professors I talked to yesterday estimates that thrust has been increased by 10 to 15% but I believe the value may be slightly higher!

I have finished adding fins and a nosecone to one of the rockets. when doing this it is important to keep the weight as low as possible. I used the cardboard that paper plates are made from. I also went with a conventional 4 fin layout as opposed to some of the more radical designs I had in mind.

I will try to test it in this configuration sometime today providing the tropical storm dosn't make landfall.

[Mark]

The two and three liter plastic Coke or Pepsi bottles are really fun too, you get a lot of hiss and they fly just as fast or faster than the little ones. They can actually annoy your ears if you light them too close to you. An easy way to light them is to clip a double strand speaker wire flush, that little gap is plenty when used with a gas grill piezo sparker. You can easily get away with stuffing the wire into the bottle, and let the jet of hot gases spit it out for you. And too, it is fun to launch from a distance this way, as long as you want your wire to be, even set it up to come flying at you or over your head.
I toyed with dry ice and making the rubber seal a burst disc or a disc that you could puncture when the bottle dropped like a mortar down a tube using a nail lined up, but with dry ice you are never really sure when the fun begins. Add some water for more jet fun. Just some things I did, a bit wreckless with the dry ice.
Nice video of the lively bottle, kind of reminds me of the exploding dry ice clip where it blew up in the guys hand, only less dangerous, albeit a memorable learning curve event.
Mark

[Mark]

I thought it would be fun to make an ultra-cheap disposable "rocket" only incorporate some pulsating combustion into the mix. I think of my Dynajet that I one time just lit the tail and it reved up full grease for a second by pre-priming/misting the insides and spritzing the intake with methanol for good measure. Believe me, holding a Dynajet in your hand just goofing around and having it rev up is thought provoking. It got hot but not too.
And my little Logan was almost a sure bet to rev up with a prime and a lighting of the tail. So if you could fashion a craft, perhaps line it with thin shim stock or foil, or anything to take the heat for a few seconds, give it a tiny reserve of fuel to feed on and you could have a supremely fun and loud valved or valveless pseudo-rocket. The V-1 effect shaped into a V-2 motif.
As an aside, if you tincture your whistling bottles with boric acid and launch them at night the green is a nice added touch.
Mark

[Mark]

With a piezo sparker and some double strand wire, it's very easy to fire these whistling bottles. You can jam the wire way into the bottle if you like, just be careful not to let the tip get shorted in a droplet of methanol, just cock it so that it terminates somewhere in the center not touching the walls of the bottle where it could get wet.
It's really a lot of fun to command such power, launching a screeching, hissing rocket faster than your eye can follow at the click of a button. If anyone tries a 2 or 3 liter bottle launch at close range, I feel certain you might be tweaking your ear with a finger from the piercing sound. It's very loud, as in Steve's video the bottle leaps far down range in the blink of an eye. Someone mentioned that it can chip or crack ceiling tile or even dry wall perhaps. Cool dry air and fresh methanol will rocket you to happiness.
Mark

[Mark]

It might be fun to pump up a 2 liter bottle to 75 psi or something and use that air pressure to interact with some methanol in some other interesting arrangement, in order to get more distance or whistle for you work. It is interesting to me that this bottle that I pumped up with air back in '92 is still holding enough pressure to stand on. Pretty neat experiment, from a time perspective. Believe it or not. I've also some other 2 liter bottles holding air as well, glued and clustered together for when I was dreaming of making a large boat out of a few thousand of them, from the same time period again.
Mark

[Mark]

Here's a 2 and 3 liter PETE Coke bottle. They are passed through a quartz glass heater where they are blow-molded into their respective shapes. Nowadays, I read that they are using a laminate of cheaper plastic in a middle layer to cut costs. When I bought these the cost of a 2 liter bottle of Coke attributed 11 cents for the price of the bottle.
Mark

[Mark]

Here's three green 2 liter bottles silicone glued together on the sides and joined end to end with another three bottles with short pieces of PVC.
Clusters of 7 bottles, (one bottle surrounded by six) make an interesting bundle and larger clusters become even more interesting. There are so many things you can make with these bottles if you use your imagination. I once had nearly a hundred arranged in a really interesting boat shape. These bottles are also holding pressure even thought the caps would rupture if stressed from bending, you'd have to seal the caps better to make something seaworthy. Still though, it is peculiar that these are still quite taunt from 1992 with nothing more than the cap they came with. I made a sleeve device that slipped over the cap with a rubber gasket to pump them up and then twisted the cap on the rest of the way to seal in the pressure.
Anyway, it was just a fun project that never got finished. I had these big dreams of the entire boat having a thousand bottle features, whistling bottles, a sheet of the bottle plastic framed and on the bottom of the boat, kind of a glass bottom boat window, a sail made from the plastic, I dreamed of taking it out to the beach on top of my car. This little cluster of 6 bottles as is makes a nice flotation device for a pool toy too.
I guess I have strayed off the rocket topic.
Mark

[Mark]

One thing occurred to me with the basic whistling bottle rocket, the kind you mist with methanol and then just blast it off. The letter of the law says it is a rocket, carrying both it's fuel and oxidizer for it's short energetic burn time. But if you could draw in/borrow a few more bottles of air gathered in flight, then it would be more like a true jet engine.
I know all this seems pedestrian, but reactants burn just the same in certain circumstances regardless of where the source of fuel/air is coming from, whether found in a tank or the ambient air, the engine doesn't care as long as it gets fed. In that respect, the separation between jets and rockets is just a formality.
Perhaps it would be fun to try entraining some air on a whistling bottle rocket by using an augmenter.
http://jetex.org/cja/images/motors/augtube50photo.jpg
http://jetex.org/cja/images/motors/augtubekit1.jpg
http://www.smallflyingarts.com/Archives ... /jetex.htm
http://www.daviddarling.info/encycloped ... entor.html
Scroll to the paragraph heading of Jetex Augmenter Tubes.
http://jetex.org/cja/articles.html
I didn't know they made a prop for Jetex.
http://jetex.org/motors/motors-accessories.html

[Mark]

For some reason I thought this little skittering Rocket Car was kind of funny. Be sure to watch the movie of it, a study in creative advertising, perhaps it appealed to the kid in me. Caution, humorous hype ahead. And they have some new substance, low-friction polypropane, probably similar to polypropylene.
Mark
http://www.antigravityresearch.com/

[Mark]

Some air amplifier reads.
Mark
http://www.vortexair.biz/Conveying/AirJet/airjet.html
And charts at the bottom.
http://www.vortexair.biz/Cleaning/Nozzles/nozzles.html
Some noise reduction.
http://www.meechairtec.co.uk/high-thrust-jet.htm
Strange buzzing sound.
http://www.schooner.com/~loverso/rocket ... /0003.html
http://www.peroxidepropulsion.com/article/17
Pulse-detonation rocket entrains more mass ...
http://www-woolf.uta.edu/arc/papers/ISA ... ichols.pdf
Mark

[Mark]

Confuser and diffuser and vibrational burning. Hmmm...
Mark
http://www.ingentaconnect.com/content/m ... 3/00491142

[Mark]

For some reason I thought this little skittering Rocket Car was kind of funny. Be sure to watch the movie of it, a study in creative advertising, perhaps it appealed to the kid in me. Caution, humorous hype ahead. And they have some new substance, low-friction polypropane, probably similar to polypropylene.
Mark
http://www.antigravityresearch.com/

Anybody want to guess at how the little mechanism works that releases the jet from the bottle, some sort of tiny balloon stent, that collapses over time? I think it is almost magic. Whatever the case, I like the simplicity.
Mark

[steve]

I haven't got up the nerve to try to launch it yet, but maybe this weekend if the weather is nice (not to humid for the methanol)

[steve]

oops, sorry I forgot to post a follow-up.
as I expected, the rocket exploded, and it was pretty spectacular.

unfortunately the nozzle was lost in the explosion but I can allways make another one.

anyway, here's the video:
enjoy

[steve]

Here's a video of one working correctly, being fired out of the bathroom!