Making a rocket engine

[RisingFury{TSU}]

Not too long ago, me and my classmate started making a rocket. We're gonna build the whole thing from the ground up, including our own motor. He's built motors in the past and ever since I showed him Orbiter Space Flight Simulator, he wanted to build a rocket again. So he invited me to come as well.

The motor is just a small test motor, made from clay. The propellant is solid fuel - potassium nitrate (KNO3), mixed with sugar in a 2 : 1 ratio.

It's used because it's cheap, easy to get... and mostly, because it's safe. Sugar and KNO3 aren't flammable when separate and are not explosive even when they are mixed together. That makes them quite safe for amateur rocketry.

The propellant is supposed to be ground up well and then either out into the engine as fine powder and squeezed or melted over a stove and "poured" into the engine and let to solidify.

But for the first 2 burns, we didn't have anything to ground the propellant with and it ended up burning slowly.


http://www.unrealaddicts.com/forums/...8/MOV05362.MPG

1st burn. The potassium nitrate and sugar weren't ground, so it burnt really slowly and produced no thrust. But it was a nice experiment.

http://www.unrealaddicts.com/forums/...8/MOV05373.MPG

Second burn. Burnt better then the first one cos we were able to grind the potassium nitrate better... but still a slow burn with 0 thrust.


1 week later:

http://www.unrealaddicts.com/forums/...8/MOV05485.MPG

Video of the 3rd burn. This time we ground up the propellant and made a hole in the middle. That meant the propellant burnt from the inside out and thus produced much more thrust and burnt cleaner.

Buuuut the engine exploded
Well, it burst and released all the propellant and the propellant quickly burnt, but no explosion.

You can see though that this and the next burn went well and produced a far better flame then the first two.



After the engine blew up...


http://www.unrealaddicts.com/forums/...8/MOV05505.MPG

After the engine blew up, we took a new one... this one blew as well, just this time the bottom blew off.


The fact that both engines blew up is actually a good sign. Why? It means that when the propellant is ground up and packed into the engine the right way, it will burn beautifully. It burnt exactly as we had expected - from the inside out. That means the mass flow increased and so did the thrust... that's what caused the engine to blow.

[TheDestroyer{TSU}]

i'm gonna start calling u Jason Fox from the comic strip fox trot

[GyPsy]

That sounds like fun, RF. Keep building.. keep the pics coming.. that is awesome.

[RisingFury{TSU}]

Images from the 3rd burn video:

Moment of ignition
Full thrust, before the explosion:


Notice how low the angle of the smoke and fire is? That's good... that means nearly all of the energy goes directly backwards, nothing goes sideways.
The second engine has an even lower angle, which means even faster moving particles.

Moment of failure



The fireball:

[Gambit{TSU}]

lmao, sweet

[Strider]

nice

[TheDestroyer{TSU}]

well when the earth gits knocked out of orbit I'll know who to

[GrendelKhan{TSU}]

holy cr!!
is that what you've been up to nowadays?? man...

well more comments later..but SWEEET!!!

[RisingFury{TSU}]

Unfortunately, no

I've only had 2 days in the last two months to blow like this. Other time, it's just studying.

[shilpaworld4]

that would be nice info. thanks for all interesting inputs


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