/sci/ - Science & Math

Test firing nozzle 2. Videos soon.

Case + fuse = 98g
Saving of 4.2g

Holds ~8.1g of fuel.(+1.3g)

First try was with 5mm nozzle hole + 3mm core, wasn't great. Got clogged and took too long.

Second try will be with 7mm hole + 5mm core

>>4161369

It's interesting to think about, everything you've said contributes. The gas gets funneled into the corners with a higher pressure is another thing.

>>4161159

Keep thinking :) There's still more

This is essentially what the first case and nozzle are like.

>>4158707

The numbers are speaking for themselves. In one day the mass flow was doubled just by tweaking the shape of the core and there's still a pile of other things to improve.

If I can find a way to measure thrust accurately I can set up a sensor and datalogger and chart a timeline of how it is burning. When I get the accurate timelines I can begin working on the tracjectories and arrangement of all the boosters.

It's looking possible to actually mould the stages directly onto each other in a stepped fashion, lighting the next stage and jettisoning themselves in one go. Having so many stages may be unheard of and not good for popular areas but the more active weight loss is convincing for helping efficiency.

This is maybe the size I'm aiming for one of the main boosters. Filled with smelted mix, full core (can design core shape for planning the burn) and possibly with oxygen inlet at the top.

The slight reduction has allowed to a better weld area. Welding should repair most of the crack that was in it but this will not be acceptable in the high power system.

Lumps are welded so it still fits in testing hole

The corners of that square are going to get silly hot compared to a circle.

Bonus points to anyone who can explain why.

>>4161008

In above picture I reduced internal diameter from 12mm to 10mm.

Found a socket that looked ok to try as a nozzle, it has a 6mm square with a 4mm through hole. Weld the slightly reduced pipe to the socket.

This should be a much better performer than Prototype #1. I shall do a sketch of the internal nozzle problem.

Showing off one of the difficulties in trying to shape a de laval nozzle. Hammering and cold working.

One way to do it is to shape two cones and join them in the center. Trying to work a pipe down to such a small diameter results in cracking and cracking can lead to explosions.

Other methods suggested are pinching a pipe. Best way I can think of doing this is with shaped high pressure rollers. This also draws the material a lot resulting in thinned walls and work hardening.

Best way is to machine it from a solid lump but this is costly and requires a quality machine.

It can possibly be accomplished with thin sheet metal to get the correct shape with a heatsink insulation to improve strength.

>>4160550

Also hydrogen is probably more affordable to make than helium but it's dangerous.

Also on the weather balloons, the expense of rigging up a launch system on a balloon is greater than just adding more fuel to the thing you're already developing.

>>4158134 I asume you're American,

Nope.

>>4159224 No De Laval nozzle? You should add a de laval nozzle

De laval nozzle is more difficult to fabricate and as you increase the strength you want the difficulty shoots up. Need some form of rolling machine.

Though I'm sure the nozzle I'm using now is getting in the way. On the inside it's an abrupt hole on the end of a piece of bar. Very far from ideal.

Currently trying to figure out a way to estimate the exhaust velocity and internal pressure. The choke in evacuating the gases means a high % of the energy put into each particle will be wasted as excess pressure and heat.

Maybe an ideal solution can be modeled and do an efficiency approximation from it.
>>4159964 Launching from balloons

Adding a balloon makes for an additional system to worry about. How can you be sure the rocket is at the right angle and not literally aiming for the ground with a full tank of fuel?

I'm curious to see what will happen with a full KClO3 / Sucrose charge, wall thickness seems sturdy enough.

>>4158737

Yes, this. Very easily done.

>>4158704 Forget about orbit, forget about space for now. You'll be taken a lot more seriously.

What's the point in doing it at all if you're not going to do it right? Orbit will be easy, it just takes a lot of fuel, careful planning and a simple thrust vectoring system.

>>4158526
Better?

>>4157918 What is it that *pops* out of the pipe just after ignition. At 3# it popped out and then rested on the board.

Wad of tissue that holds the fuse and blocks stray sparks.

>>4158526
>implying metric doesn't

Did some calculating to get an idea of the mass flow. Measured roughly the time it took for the fuel to ignite properly until the last puff of smoke.

Times were taken from the sequenced video. Due to the short unsteady burn it's hard to say the peak velocity because they all linger a little bit. Larger motor that burns longer will be better for guessing peak flow.

Highest avg is up to 0.5g/s

>>4157595

Watching the videos I'm going to say the velocity of the fuel leaving is getting faster each time, basing it on the shape of the smoke leaving the nozzle.

I think in #3 the full depth core made more difference than the KClO3. There was a little yellowy shit left which I'm sure was down to this messing with the mixture.

If I can thread the outside of the pipe then I should be able to pour a smelted mix in easily. The smelted mix might be good as the fuel for a hybrid motor that uses either pure oxygen or just compressed air.

>>4157595

Test #3 was also cored 4mm the full length

http://www.megaupload.com/?d=4K1NEKCC

3 vids

password is sci