Water Rocket Forum

Check out our booster rocket launcher:

These are the steps that we took when making the launcher:
[youtube][/youtube]

How it works:
[youtube][/youtube]

For more details visit:
http://tdfwaterrockets.blogspot.com/

From

TDFwaterrockets

Hey guys, that's really good work!

I'm going to see the videos now!

Hi TDF Water Rockets,

That's a really nice looking launcher you designed. We really like how you've designed in a way to adjust the booster launch tubes to adjust for different size rockets. That's very ingenious!

I can't see the video of the launches. YouTube says the video is no longer available. The launcher video is great though. It was 2 months well spent. That should serve you well for many years to come!

Andromeda wrote:I can't see the video of the launches. YouTube says the video is no longer available. The launcher video is great though. It was 2 months well spent. That should serve you well for many years to come!

I had the same problem but I reloaded a few times and it loaded and played. Give it another try. It's a video you don't want to miss!

Here is a video of the test launches:
[youtube][/youtube]

Very nice work on the launcher and rocket Tom!

How do you guys fill the boosters with water? Do you have to invert the whole launcher?

air.command wrote:Very nice work on the launcher and rocket Tom!

How do you guys fill the boosters with water? Do you have to invert the whole launcher?

Hi Aircommand

No, we don't invert the launcher. We simply fill the boosters up with water and quickly slide them onto the launcher, if we do it quick enough then no water comes out.

TDFwaterrockets

TDFwaterrockets wrote:

air.command wrote:Very nice work on the launcher and rocket Tom!

How do you guys fill the boosters with water? Do you have to invert the whole launcher?

Hi Aircommand

No, we don't invert the launcher. We simply fill the boosters up with water and quickly slide them onto the launcher, if we do it quick enough then no water comes out.

TDFwaterrockets

You should modify your launcher to fill the boosters with water from the mainfold below. If you do it my way you won't have to measure the water levels with great precision. I just have a piece of tape on the side of the rocket that I use for a water level marker. When I can see the water level at the right spot I stop water filling and switch to air. My opinion is that gravity will insure all of the boosters will have exactly the same water level in them because it will act as a level.

Andromeda wrote:

TDFwaterrockets wrote:

air.command wrote:Very nice work on the launcher and rocket Tom!

How do you guys fill the boosters with water? Do you have to invert the whole launcher?

Hi Aircommand

No, we don't invert the launcher. We simply fill the boosters up with water and quickly slide them onto the launcher, if we do it quick enough then no water comes out.

TDFwaterrockets

You should modify your launcher to fill the boosters with water from the mainfold below. If you do it my way you won't have to measure the water levels with great precision. I just have a piece of tape on the side of the rocket that I use for a water level marker. When I can see the water level at the right spot I stop water filling and switch to air. My opinion is that gravity will insure all of the boosters will have exactly the same water level in them because it will act as a level.

That's a good observation.

Andromeda wrote:

TDFwaterrockets wrote:

air.command wrote:Very nice work on the launcher and rocket Tom!

How do you guys fill the boosters with water? Do you have to invert the whole launcher?

Hi Aircommand

No, we don't invert the launcher. We simply fill the boosters up with water and quickly slide them onto the launcher, if we do it quick enough then no water comes out.

TDFwaterrockets

You should modify your launcher to fill the boosters with water from the mainfold below. If you do it my way you won't have to measure the water levels with great precision. I just have a piece of tape on the side of the rocket that I use for a water level marker. When I can see the water level at the right spot I stop water filling and switch to air. My opinion is that gravity will insure all of the boosters will have exactly the same water level in them because it will act as a level.

Hi Andromeda,

While that technique works well for single rockets, it does not work well in practice with independent boosters. The problem is the trapped air in each booster being at slightly different pressure as you fill it. With the inherent non-symetry of the manifold you inevitably end up with different amounts of water in each booster. If the boosters are connected via the manifold below the waterline what ends up happening is that as you start to pressurise the boosters with air each will again have slight differences in air pressure and the pressure difference will start transferring the water from the boosters with slightly higher pressure to the ones with the slightly lower pressure. Even differences less than 0.1 psi are enough to transfer a lot of water. We found out the hard way on our first launcher. You want to be able to equalize the pressure between the boosters without transferring any of the water.

The way Tom has it is correct. You could perhaps fill the rocket with water as you suggest through the air fill tubes as long as the water outlets are above the water line, but you would have to live with any differences in water level, that end up in each booster again due to the non-symetry of the manifold. You will not be able to achieve the "spirit level" effect though to equalize the water level. And again the air pressure difference will force the water left in the manifold into the booster with the least pressure. (you could keep the tubes thin to reduce the amount of water left)

Alternatively you could equalize the air pressure in each booster by connecting them together with small tubes at the top like Batkier does on his big booster, but that makes it more difficult to have them fall off independently.

Tom, if you splice the boosters so that you have an open neck at top of each booster, you can just place them dry on the launcher and pour a measured quantity of water in from the top, and then just cap them.

Hi Aircommand

We were going to do that but we cant find any glue that is good for splicing. We could buy it online from another country but we have got a simpler way of sorting it. We will couple them together, which we have done many times before. The only reason why we haven't done that yet is because we are starting off with a small rocket and if the booster are spliced together then they will be too big for the main stage. After we get the rocket working properly then we will move up to a bigger rocket and bigger boosters.

Tom
TDFwaterrockets

Ahh no worries, ... definitely better to take it a step at a time. I'm looking forward to your next blog update.