You won't launch it into the sky from under the water.
And why do you say this exactly? Have you tried this experiment yourself? And assuming you have (in order to denounce it so strongly) how did you utilise the three materials, and what did you use for your rocket casing? BTW, what purpose does the powdered aluminium serve?
What do you mean what purpose does it serve?
We are talking about rockets taking off from under water. We don't need to go into stuff like thermite and what not. We are talking about moving a ballistic missile from under water into the sky.
We are told that compressed air shoots the missile out of the water, then the rocket burn kicks in and off it goes.
Some videos show this happening.
Other videos show the rocket coming out of the water already ignited.
I'm telling you right now that neither can happen in how we are shown.
Not a hope in hell are you going to get a 20 odd foot long ballistic missile through 120 feet of water by air pressure to jump out of the sea, then to ignite and on it's merry way.
Not a hope in hell.