Building a new launcher, need advice.

[n0face]

After breaking my plastic launcher last week I am looking to make a new launcher from copper plumbing parts.

I would like to include a check valve emergency dump and PSI meter. I would also like to be able to fill the bottle with water while it is on the launcher as I am using 22mm nozzles and a launch tube which I have found awkward to get the rocket on without tipping a launcher over.

I would like to know:-

will standard plumbing parts stand up to air pressure, will a Check valve like this work?

I was considering using a second check valve in the launcher on a T joint connected to a water hose and pumping water into the rocket using a 2ltr bottle with a hose at one end and a bicycle valve in the other to pump the required amount of water into the rocket while its on the launcher does anybody know if this might work or had experience with a similar idea (I'm sure I saw this somewhere rather then coming up with the idea myself)?

As the launcher past the Air non return valve would deal with both water and compressed air would a PSI meter still work?

Considering using a Full Bore Lever Ball Valve 22mmas the emergency pressure dump valve with a piece of string and some kind of pulley mechanism to activate it, do people thin k this may work?

Any advice or suggestions would be greatly appreciated.

[n0face]

they say a picture is better then a thousand words.

[n0face]

Just found the site where I got the idea Here it is

basically the same idea but without mains pressure. Pic below from their site.

(sorry for the multipost but can't find an edit function.)

[SaskAlex]

Noface, here are my two cents. If you are using a full bore nozzle, then you can easily make the launch tube long enough to go up passed the water line in the rocket. Then there is no need for any check valve- the water inside the rocket won't be able to get back into the launcher. Without the check valve on the main line, you don't need a ball valve for emergency pressure dump because you can just disconnect your pump from the line. Oh, and I've done the 2L bottle thing for filling before. It works fine. You can use it right on the end of your air line, too, if you only want to use one line.

I'd also recommend mounting the pressure gauge on the end (the pumping end) of the air line rather than on the launcher. That way you can see it much more easily. That will be really important if you ever move to a really long air line.

Alex

[n0face]

Cheers for the response Alex

The Idea of the check valve was because I want to start trying higher pressures so I'm rating everything to 250psi+ and thought it would be better to keep the pressure in as close to the launcher as possible and because of this giving myself a longer hose to be an adequate distance from the launcher, hence the need fill up with water closer to the launcher and have a release valve.

Great news that you've filled your rockets with the rocket on the launcher method (catchy name) and its worked. It's such a pain trying to get a large rocket on the launcher without loosing to much water or water running down the launch tube.

[n0face]

Also the idea of having a pressure gauge on the launcher came from reading that it was preferable in WRA2 rules to do so although I may have got that wrong as I have only scanned the rules and a few threads on the subject.

(sorry again for the multipost need to collate my thoughts before hitting submit, or find an edit button.)

[SaskAlex]

I wouldn't worry about making multiple posts in a row. I just don't see how that's a problem.

Anyways, what I'm really posting about is your water filling method. Are you using spliced rockets? Do you plan on it any time soon? Because I find simply filling the rocket through the top, while it's on the launcher, far simpler and quicker than the 2L bottle thing. If you do go with the bottle route, try to keep the restrictions between it and the launcher to a minimum. It's surprising how much pressure it takes to pump water through valve stems and things like that, even at a fairly slow rate.

[WRA2]

Also the idea of having a pressure gauge on the launcher came from reading that it was preferable in WRA2 rules to do so although I may have got that wrong as I have only scanned the rules and a few threads on the subject.

(sorry again for the multipost need to collate my thoughts before hitting submit, or find an edit button.)

The pressure display only applies to certain competitions. It would be a great way of proving the "max pressure hold if competing in the single or multi stage world record competitions using air tank as a pressure source though It just needs to be visible to the point of being able to see the needle does not jump just prior to launching (stomp rocket). For our pressure limited competitions it does need to be visible and legible.

As a new benefit of WRA2 membership I have enabled editing for WRA2 members for the most used forums. (let me know if it is still not working and I will investigate further). Multiple posts are not a problem so non-members don't have to worry about it either.

[Drake Stutesman]

check my post, called easiest launcher to make.

[n0face]

@Alex, I've thought about splicing bottles but living in the UK the glues that people are using aren't available. However even with a spliced rocket if you filled it from the top would you not just be pouring the water down the launch tube and wouldn't you have to assemble the rocket (put the nose cone/payload etc on top) on the launcher after it had been filled with water.

@Drake, your launcher looks great and similar to what I'm trying to achieve, I may be trying to overcomplicate things but as this is the second launcher I've built I would like to try and include as much as I might possibly need to future proof it as much as possible.

The Goal is to make a Launcher that can take 250psi as safely as possible.

I post on a couple of other forums where multiple posts are frowned on, seeing as people don't mind it here I'll stop worrying.

Cheers.

[SaskAlex]

Yes, it's too bad about the limited availability of suitable glues for splicing rockets. But the same filling technique could also be used for Robinson coupled rockets. Yes, you do have to assemble the parachute/nose assembly while the rocket is on the launcher. That's fine for me, because I have an internal release mechanism, so the payload section has to come off anyways to set the parachute release. I guess it might be annoying if you wanted to have a permanently mounted parachute module.

And when you fill from the top, it's easy to get the water to flow down the side of the rocket, so that it doesn't pour into the launch tube. Your launch tube just has to be a little shorter than the rocket, or you don't put your rocket all the way down while you fill. And if you have a check valve anyways, it doesn't matter if some water goes down the launch tube.

[U.S. Water Rockets1]

they say a picture is better then a thousand words.

The 2 liter bottle with water in it inline with the pump is confusing and looks like it would be a weak point. What's the purpose of that bottle? Are you trying to maintain a water level in the rocket by displacing the water level equally in both the rocket and the bottle? You don't need a large volume to do that. Water in the hose itself would do the same thing.

[n0face]

A picture being worth a thousand words isn't very good if you're mumbling, I can see what you mean that the picture could be confusing.

The idea is that the 2ltr bottle with hose is just used to fill the rocket with water and the check valve holds the pressure in the launcher and rocket when pressurising from the other hose. This hopefully would make it easier to prepare the rocket on the launcher.