air-augmented rocket based in NASA prototype

[RaZias]

I read this at http://en.wikipedia.org/wiki/Air-augmented_rocket

"Air-augmented rockets (also known as rocket-ejector, ramrocket, ducted rocket, integral rocket/ramjets, or ejector ramjets) use the supersonic exhaust of some kind of rocket engine to further compress air collected by ram effect during flight to use as additional working mass, leading to greater effective thrust for any given amount of fuel than either the rocket or a ramjet alone."

Then I thougth...I not to use the compression made by the air exhaust from the water rocket ? I know it´not supersonic speed but the site also refers the following:

"able to give useful thrust from zero speed, and are also able in some cases to operate outside the atmosphere, with fuel efficiency as good or better than both a comparable ramjet or rocket at every point."

In fact most of the rockets are air-augmented rockets

"Many modern solid fueled 'ramjet' powered missiles may in fact be air augmented rockets, and the distinction between a ramjet and an air augmented missile is rather blurred. Many solid fueled ramjet missiles seem to be solid fueled ramrockets in all but name"

So what´s my point ? Well just take a look to this picture

http://upload.wikimedia.org/wikipedia/e ... fny-f2.jpg

(If someone could post this post with the image I would appreciate because I am a noobie)

I was thinking in changing the front cone in the exhaust tube entrance by a water-rocket.
To be effective for the low-air volume relese of the water-rocket compared with an real rocket engine I think it would be necessary to narrow the outlet tube
(or air escape tube that will surrond the nozzle of the water-bottle)

I know it´s to much exotic, but if someone has a "home-made wind-tunnel" (I don´t remember who in this forum) it should give a try!

[Tim Chen]

I am unsure this is going to help a water rocket because these types of motors all use combustion to generate their thrust and compressing extra oxygen into the engine is how they get more thrust from this method. With a water rocket there is no combustion, so it may not help.

One idea I was thinking about would be to inject compressed air into the nozzle of a water rocket to generate bubbles which should act as a compressed gas and expand in a similar way as the bubbles expand. This would allow the use of a DeLaval C/D nozzle to gain extra thrust. The air bubbles injected directly in the exhaust stream would give all the benefits of using soap bubble foam without the drawbacks (protracted thrust time, messy, kills grass, unexpelled bubble residue, and so on...)

I'm pretty sure there is some gains to be had with these experiments!

[RaZias]

Sorry by the question but what is a " DeLaval C/D nozzle " ?

Anyway I think I fond a way to inject air into the water stream to make bubbles and gain more thrust.
I will try to use an Gardena Nozzle that in the part that is inside the bottle as a small vertical tube with 2 orifices.

I am thinking to make the orifices at different heights so the water enters in one hole and the air by another.
To be more effective the water must enter by the most tall one (maybe using a ballon) and the air by the lowest one. Getting the water going to the ballon without going out by the another one might be tricky.
I will need to think in away to solve this problem.