AirCowPeacock Posted October 30, 2012 Posted October 30, 2012 I'm thinking about lifting shells with these things, but theyre certainly cool without.
usapyro Posted October 30, 2012 Author Posted October 30, 2012 Your not going to be able to lift very big of a shell with one of these. Ill try to get time to test a very low nozzle angle/high thrust one for you sometime. But, why can't you test yourself?
AirCowPeacock Posted October 31, 2012 Posted October 31, 2012 I will when I get back home. Im on vacation for the next few days. I'm certainly very excited to make some when I get home.
usapyro Posted October 31, 2012 Author Posted October 31, 2012 (edited) I thought about how to lift a shell with one of these... You will need to ram a very slow low dross delay into the nozzle. Why? You want the high thrust to hit instantly if you want one of these to lift anything and have a stable flight. You want zero dawdling around at launch!!! I would also recommend a high nozzle offset so the nozzle vents put real torque into spinning the motor asap. I don't design them to launch without a guide tube anymore. In order to have them launch reliably without a guide tube like shown in video two... You need a delay slow enough it can't tip the motor over from one of the vents and you must have delay rammed right to the main grain. Anyone know of a really good low dross delay formula for use in rocket engines? One that has very little gas production and burns real slow. I might go back to launching them without a tube if I can find a good delay formula. Just using sugar smoke bom mix at the moment. LoL! Edited October 31, 2012 by usapyro
AirCowPeacock Posted October 31, 2012 Posted October 31, 2012 Seems like the last thing I would want to use. You could try a stochiometric KNO3:C mix with some (Say 2%-7%) inhibition agent--like CaO or NaHCO3. Dross might br an issue. Just a guess.
AirCowPeacock Posted October 31, 2012 Posted October 31, 2012 You could always plan for dross with a bigger nozzle.
usapyro Posted October 31, 2012 Author Posted October 31, 2012 (edited) The dross has not been a "flight" issue so far and has not caused any cato's. I just launched a couple. I have a problem that needs solving... See the video below. The thing has one increment of 50:50 BP/SF then it switches over to 50:50 BP/SF + 15% pine charcoal (Rough, just blended in a bullet blender and nothing more.). Notice as it goes up that the sparks go away to the point it's nearly invisible? And it's only like sixty feet up or so. Really strange lack of sparks for a fuel with 15% blended pine, huh? Look closely... As it rotates faster and faster the sparks go away. You see an intermittent sputter as it throws out a few sparks. What I think is happening is that the dross in addition to the outward pushing force generated by the crazy rotation speed is trapping the charcoal against the sides and preventing it from coming out of the nozzles. I know that it must be a combination of both because I had one of these get stuck in my tube launcher and it threw TONS of sparks the entire time until it blew up. Maybe a plain BP fuel without sugar will solve this issue... Or maybe it's merely the high rotation speed holding the charcoal against the sides of the engine and not letting it out that is the issue. There are a couple potential solutions to this problem... I have a hunch solution two is the only way to go. 1. Plain BP based fuel.2. Lower rotation speed. Lower offset even more and maybe add something to create friction to prevent insanely high RPM rotation.3. Angle my internal nozzle. Would probably help... I am using flat faces from the main grain into the internal nozzle right now, not the Optimal Design. http://www.youtube.com/watch?v=1kqaaNFjjlM&feature=plcpCool new launcher huh? See here at the end... There is the missing pine charcoal appearing with the 1g FeTi and 5g Flash report... It needs that report to knock it out of the motor! Haha... You know, that is kind of an interesting unintended effect... I figured out how to trap tons of hot charcoal inside a motor until a report frees it!!! The irony... I can't get my "Flying Fountain" to fountain because it's trapping all the charcoal or metal inside... Hah!http://i46.tinypic.com/nzkuuh.jpg I thought it was kind of strange how long the spark tail lasted after the bulkhead blowout in video two... Now I know why that spark tail occurred!!! Edited October 31, 2012 by usapyro
usapyro Posted October 31, 2012 Author Posted October 31, 2012 (edited) The problem is confirmed to be the rotation speed. The issue bugged me so much I had to go out and test. I launched one with BP + 20% Pine Charcoal... No delay. That fuel only!!! Jesus... This thing is a centrifuge rocket... Unbelievable! It was rotating fast enough to centrifuge the charcoal sparks out of burning BP!!! This also explains why I was having so many issues with bulkhead blowouts before too. Notice how the number of sparks in the other videos steadily declined during flight? This is because as the grain burned farther there was both a longer centrifuge area the sparks had to cross and the rotation speed was increasing with time! http://www.youtube.com/watch?v=CGM6m2ZyNTg Next test ill add a sloped internal nozzle and see how much better it works... While keeping the same vent nozzle positions and rotation speed. Then ill bump the rotation way down with a low offset. I will continue to use the high offset tooling (high rotation speed) for a couple more tests to judge how much of an improvement a sloped internal nozzle is. Perhaps the centrifuged charcoal can manage to be pushed up a slope by the gas flow even at a pretty high rotation speed. Btw... AirCowPeacock... I solved the only way your only going to be able to lift a decent sized shell with one of these... Your going to need a propellor to generate extra lift. This design is very thrust inefficcent, but decently efficcent when it comes to rotation speed and torque with a high offset on the nozzles. Experiment and see what happens! Edited October 31, 2012 by usapyro
AirCowPeacock Posted October 31, 2012 Posted October 31, 2012 A propellers not a bad idea. But how am I going to 'easily' make some with enough strength? Hmm.. Kraft paper and wheat paste? That's the pyros solution!
spitfire Posted October 31, 2012 Posted October 31, 2012 Very interesting new design! Might become a new type of novelty. I suggest more people should (including myself) do some tests, and see what we all come up with. This might be a stinger 2.0.... and really skilled tool-guys...: jump on this one!
usapyro Posted October 31, 2012 Author Posted October 31, 2012 (edited) Besides the name "Flying Fountain" I have also thought of calling it a "Canister Rocket". You can actually launch these out of small mortar tubes with lift like a mortar shell... LoL! Ram that bottom bulkhead in tight and ram the vent holes full of BP meal with a little blackmatch sticking out... It will stay aligned properly both because rotation will start during flight and the tip is heavyier because of the large nozzle setup. Btw, here is one way to do a propellor... I may actually add these just to tune the spin rate even after I lower the offset way down. Just cut squares of balsa and hot glue them on above the nozzles. Should work! Won't be able to launch them out of a mortar with lift anymore though. Someone experiment with this and see how well it works for converting the rotation into extra lift! It's definitely not the most efficcent propellor design! http://i47.tinypic.com/2rzuall.png Edited October 31, 2012 by usapyro
superspike23 Posted October 31, 2012 Posted October 31, 2012 (edited) you tried with aluminium composition? it is hotter , it should better resist to centrifugal force your salute is very loud! what composition did you use? Edited October 31, 2012 by superspike23
AirCowPeacock Posted October 31, 2012 Posted October 31, 2012 Ill try those out. I might just stick to salutes for these. They would be great for pattern shells--but it might not be feasable. I'll see what I can do though.
usapyro Posted October 31, 2012 Author Posted October 31, 2012 (edited) Btw, here is the rounded angle I am using to shape the choke into the internal nozzle now. As the hot charcoal gets higher up the slope it should be pulled in easy even at pretty high rotation speeds. Lowering my offset way down in the next test videos ill put up. http://i47.tinypic.com/jl16hh.jpg I have been using the same hardwood dowels (ironwood or oak, not sure) for three years for rockets and have not had any issues with wear or splitting. You just have to put a thick black tape ring around the back a quarter of an inch in to prevent it from splitting downward. Re superspike: Charcoal is lighter than Al, so Al would be much worse. With FeTi not even a single spark escaped when using a one 50:50 incriment to launch! The hotter the composition burns the faster the rotation speed is. I used the normal 70/30. But, what I do is I ram the bulkhead... Put a hole in the center, not the side! Put the flash in, then lightly ram clay over it. There is still a bit of chamber pressure when the flash goes. Even with 2g Flash these things are reduced to confetti if you use flash mid bulkhead like that. Edited October 31, 2012 by usapyro
superspike23 Posted October 31, 2012 Posted October 31, 2012 it should be ok with pyro tail composition on top
usapyro Posted October 31, 2012 Author Posted October 31, 2012 Thats a neat idea... But, I would reccomend just running a seperate outside fuse to it with a specific length. That hole would be more problematic than you think.
usapyro Posted November 1, 2012 Author Posted November 1, 2012 (edited) Ok... I tested with an extremly low offset... Only a few mm per side. The thing still rotates so fast it centrifuges the charcoal. Not bothering to upload the videos! Very Low offset (3mm per side) - Charcoal trail dies off at...1600ms from liftoff High Offset - Charcoal trail dies off at...750ms from liftoff While it's an improvement... The charcoal tail still gets choppy before the complete die off time. These tests were done with Black Powder + 20% charcoal again. Straight choke, not rounded. I drilled the nozzles wrong on my ones with the new rounded angled chokes and those will have to be redone tomorrow to see how long the charcoal tails last on those. Perhaps the rounded angled choke will solve it... Fingers crossed on a combination of low offset and rounded angled choke. If this doesn't work it requires propellers for a spark effect from the motor! Edited November 1, 2012 by usapyro
usapyro Posted November 1, 2012 Author Posted November 1, 2012 The vents are offset a few mm from the middle... Eg... http://i50.tinypic.com/azfq1.jpg
AirCowPeacock Posted November 1, 2012 Posted November 1, 2012 (edited) I see. I'm going to encoperate these into my little backyard (not really in my backyard) newyears display. I'm going to have two and try to add some color (red and green probably.) I'm trying to use my Sr(NO3)2 and Ba(NO3)2 for colors as much as possible because I'm running low on KClO4. So one might mistake my newyears fireworks for christmas fireworks. I will be one of the first people to every make these. My friends and family will be be one of the first to ever see these. Edited November 1, 2012 by AirCowPeacock
usapyro Posted November 1, 2012 Author Posted November 1, 2012 Ohhh, if you find any good fast burning green/red flare or star mixes that work as rocket fuel be sure to post them. I wonder how they do color flame in ground blooms...
usapyro Posted November 1, 2012 Author Posted November 1, 2012 (edited) Btw, here is something kinda interesting... I uploaded a video one of my incorrectly drilled Flying Fountains being lit last night. I just drilled holes straight into the nozzle at the end and ignited em. By the burn time and sound I think there was two nozzles firing... One offset and angled, and the one straight into the middle. I tell you... In person watching that crazy thing fly around making those popping noises it felt like it was going on for five minutes!!! I think those were bursts of charcoal hitting the nozzles... The other one wasn't so interesting. http://www.youtube.com/watch?v=hVgOlAUUIPg Edited November 1, 2012 by usapyro
superspike23 Posted November 1, 2012 Posted November 1, 2012 Ohhh, if you find any good fast burning green/red flare or star mixes that work as rocket fuel be sure to post them. I wonder how they do color flame in ground blooms... fast compostion for rocket engine. it's not red or green , but yellow: potassium perchlorate 90cryolite 26mg/al 60pvc 10c 4dextrin 10 http://youtu.be/q87rdvnM7t8
AirCowPeacock Posted November 1, 2012 Posted November 1, 2012 Im planing on using BP:SF (50:50) for and increment or two then switching to my color comp. So I dont really need a rocket fuel for the color--cuz it will already be going pretty good. Plus I dont have any cryolite.
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