Water Rocket Forum

I'm trying to figure out the air supply for my new launcher. My original plan was to use my bike pump. I wonder how it will do with 50' of hose to the rocket. Does anyone have advice about long lines from a floor pump (the kind you use with your hands, not a foot pump). Are there any problems associated with long hose runs from a hand pump? Is it better to go with 1/4" hose, or 3/8"?

Narrower is better since you aren't trying to push a bunch of air through it. You will have less internal volume to pressurize as well. You could probably go down to 1/8" .

I do. I usually have used a 25 50' long aircompressor hose and used JB weld to attach it to shcrader thingy. Also be sure to check if the schrader thingy already screws into that thread.

bugwubber wrote:Narrower is better since you aren't trying to push a bunch of air through it. You will have less internal volume to pressurize as well. You could probably go down to 1/8" .

1/4" seems pretty easy to find. I'm having a hard time sourcing 1/8". Do you have any suggestions? Our airbrush hoses are 1/8", but the longest one I have is 15', and I can't find anything online longer. It seems like most shops going with longer runs on airbrushes use a larger line and fit it down to the airbrushes at the working end. Is there another type of hose that works for this? Also, I'm not sure airbrush hose can take the pressure for rockets. I'm pretty sure the most pressure we ever use with the brushes is 60psi.

Water Rocket Expert wrote:I do. I usually have used a 25 50' long aircompressor hose and used JB weld to attach it to shcrader thingy. Also be sure to check if the schrader thingy already screws into that thread.

I'm thinking that your post is saying that you use a 25-50' hose? As for the pump end I'm planning on using a Presta valve so that It will protect my pump from any water that may get into the line. What I've done in the past is to shove the valve into a hose, and wire it one with 18g stainless wire. I've had good luck with no leaks up to 120psi with that, and I've never tried more pressure (bike tire).

[quote="Jtrops1/4" seems pretty easy to find. I'm having a hard time sourcing 1/8". Do you have any suggestions? Our airbrush hoses are 1/8", but the longest one I have is 15', and I can't find anything online longer. It seems like most shops going with longer runs on airbrushes use a larger line and fit it down to the airbrushes at the working end. Is there another type of hose that works for this? Also, I'm not sure airbrush hose can take the pressure for rockets. I'm pretty sure the most pressure we ever use with the brushes is 60psi.
[/quote]

Searches on the Web turn up some interesting products like this that come in a variety of sizes:
http://www.freelin-wade.com/nylon-11--- ... -l-en.html

You could probably find something at the home and farm stores in their bulk tubing section.

bugwubber wrote:
Searches on the Web turn up some interesting products like this that come in a variety of sizes:
http://www.freelin-wade.com/nylon-11--- ... -l-en.html

You could probably find something at the home and farm stores in their bulk tubing section.

Thanks for pointing me in the right direction. I wasn't even considering hose that wasn't "air hose." I'm gonna check out the local home store to see what they have.

From what I can gather the safe maximum working pressure for 1/4" drip irrigation line is around 200psi. That stuff has an outside diameter of 1/4" and an inside diameter of around 5/64, or just a bit bigger than 1/8". With that in mind I may try to use it since it is readily available, and I don't plan on using anywhere near the safe working psi. If it works it will be nice and light to travel with.

At this point I'm considering using an old plastic milk crate for my launcher base. The launch mechanism will attach with wing nuts through the crate so that it can be taken apart and put inside the crate for storage/travel. The air line and everything else associated with the launcher should have plenty of space in the crate as well. I will try to get a launch this weekend. Next week my students will be building rockets!

The PE 1/4" drip line tubing works great. It was a bit of a trick getting my valve into the end since the tubing is fairly stiff plastic, but not too bad. A better way to do it might be to use a small section, maybe 2", of air hose glued to the end of the PE, and then a hose clamp to attach a valve to the air hose. With my bike pump it only took 6 pumps to get the rocket to 60psi.

Jtrops wrote:The PE 1/4" drip line tubing works great. It was a bit of a trick getting my valve into the end since the tubing is fairly stiff plastic, but not too bad. A better way to do it might be to use a small section, maybe 2", of air hose glued to the end of the PE, and then a hose clamp to attach a valve to the air hose. With my bike pump it only took 6 pumps to get the rocket to 60psi.

Sweet! The plastic curlyque hose that came with my 12v launcher was annoying me so I just picked up 100' of 1/4" OD of PE tubing and some brass adapters so it can screw directly in to the launcher. $6 for the PE tube.

bugwubber wrote:

Jtrops wrote:The PE 1/4" drip line tubing works great. It was a bit of a trick getting my valve into the end since the tubing is fairly stiff plastic, but not too bad. A better way to do it might be to use a small section, maybe 2", of air hose glued to the end of the PE, and then a hose clamp to attach a valve to the air hose. With my bike pump it only took 6 pumps to get the rocket to 60psi.

Sweet! The plastic curlyque hose that came with my 12v launcher was annoying me so I just picked up 100' of 1/4" OD of PE tubing and some brass adapters so it can screw directly in to the launcher. $6 for the PE tube.

Didin't A.G.R. use irrigation tubing for their high pressure flights? They said somewhere how they connected the launcher to the tank. They used a small diameter tube so it was not under a lot of stress.

The launcher we just designed, has a 25-foot hose, 1/4" OD, 0.17" ID, 140 psi, and we use a bicycle pump to pump it up. (Got the hose at Home Depot, they also have the compression fittings to hook it to a tire valve and to the 1/2" PVC fitting on the launcher).

No problems yet!

If the hose were 50 feet long instead of 25, that would give us "a little" more volume to pressurize, but how much more?

Let's see, pi * r-squared * L, gives 6.8 cubic inches volume inside the hose if it doesn't expand, for a 25-foot-long hose. Slightly less than a cube 2" on a side. That doesn't sound like a whole lot to me.

Little-Acorn wrote:The launcher we just designed, has a 25-foot hose, 1/4" OD, 0.17" ID, 140 psi, and we use a bicycle pump to pump it up. (Got the hose at Home Depot, they also have the compression fittings to hook it to a tire valve and to the 1/2" PVC fitting on the launcher).

No problems yet!

If the hose were 50 feet long instead of 25, that would give us "a little" more volume to pressurize, but how much more?

Let's see, pi * r-squared * L, gives 6.8 cubic inches volume inside the hose if it doesn't expand, for a 25-foot-long hose. Slightly less than a cube 2" on a side. That doesn't sound like a whole lot to me.

To be honest I didn't even feel the difference in pumping up our 1 liter bottles one third filled with water. When we put a two liter bottle on it seemed to take forever to get it up to pressure. I don't think the volume of the line is very significant at all.

I made an extension out of half inch PVC pipe to get the fins another few inches below the bottle. So the nozzle attaches to the pipe, the fins are on the pipe, and the pipe attaches to the bottle. The fins are going on this evening, and hopefully we'll be launching in a couple of days. I didn't even think about it before your post, but I'm sure there will be more pumping with the new rocket.

Jtrops wrote:

Little-Acorn wrote:The launcher we just designed, has a 25-foot hose, 1/4" OD, 0.17" ID, 140 psi, and we use a bicycle pump to pump it up. (Got the hose at Home Depot, they also have the compression fittings to hook it to a tire valve and to the 1/2" PVC fitting on the launcher).

No problems yet!

If the hose were 50 feet long instead of 25, that would give us "a little" more volume to pressurize, but how much more?

Let's see, pi * r-squared * L, gives 6.8 cubic inches volume inside the hose if it doesn't expand, for a 25-foot-long hose. Slightly less than a cube 2" on a side. That doesn't sound like a whole lot to me.

To be honest I didn't even feel the difference in pumping up our 1 liter bottles one third filled with water. When we put a two liter bottle on it seemed to take forever to get it up to pressure. I don't think the volume of the line is very significant at all.

I made an extension out of half inch PVC pipe to get the fins another few inches below the bottle. So the nozzle attaches to the pipe, the fins are on the pipe, and the pipe attaches to the bottle. The fins are going on this evening, and hopefully we'll be launching in a couple of days. I didn't even think about it before your post, but I'm sure there will be more pumping with the new rocket.

I'm sure that's so.

As long as the hose is fairly narrow, it doesn't add much to the volume you have to pump up. Most of the volume is still the rocket itself. And yes, 2-liter bottles certainly take longer!

I saw one fellow who put together a launcher with a CLark-type lock, which worked pretty well. But instead of a hose, he ran two lengths of 1/2" PVC Schedule 4 pipe from the launcher to his pump, with a Schrader valve in the end cap of the last length. That one took a LLLOOONNNG time to pump up!

Little-Acorn wrote:

Jtrops wrote:

Little-Acorn wrote:The launcher we just designed, has a 25-foot hose, 1/4" OD, 0.17" ID, 140 psi, and we use a bicycle pump to pump it up. (Got the hose at Home Depot, they also have the compression fittings to hook it to a tire valve and to the 1/2" PVC fitting on the launcher).

No problems yet!

If the hose were 50 feet long instead of 25, that would give us "a little" more volume to pressurize, but how much more?

Let's see, pi * r-squared * L, gives 6.8 cubic inches volume inside the hose if it doesn't expand, for a 25-foot-long hose. Slightly less than a cube 2" on a side. That doesn't sound like a whole lot to me.

To be honest I didn't even feel the difference in pumping up our 1 liter bottles one third filled with water. When we put a two liter bottle on it seemed to take forever to get it up to pressure. I don't think the volume of the line is very significant at all.

I made an extension out of half inch PVC pipe to get the fins another few inches below the bottle. So the nozzle attaches to the pipe, the fins are on the pipe, and the pipe attaches to the bottle. The fins are going on this evening, and hopefully we'll be launching in a couple of days. I didn't even think about it before your post, but I'm sure there will be more pumping with the new rocket.

I'm sure that's so.

As long as the hose is fairly narrow, it doesn't add much to the volume you have to pump up. Most of the volume is still the rocket itself. And yes, 2-liter bottles certainly take longer!

I saw one fellow who put together a launcher with a CLark-type lock, which worked pretty well. But instead of a hose, he ran two lengths of 1/2" PVC Schedule 4 pipe from the launcher to his pump, with a Schrader valve in the end cap of the last length. That one took a LLLOOONNNG time to pump up!

A lot of people add tanks or volume to their launcher because they think the extra air capacity will give their rocket more boost. Usually this is done for distance competitions. That's a really popular trick that's been used for close to 20 years. They usually have a team of pumpers so the extra volume is shared by several members in parallel or taking turns. It's really literally a good example of teamwork.

I wonder how long it would take to pump up my 12-liter rocket..... Forever, I guess? Seriously, are there no pumps with high output?

I have 5m of air hose, first 3m is a 14mm OD then reduces to a 6mm braided hose.... Do I have to replace it with smaller diameter hoses if I'd use an HP floor pump? I'd like to launch at 110 psi.

the size of the hose does not determine the amount of psi but it will determine the amount of time it will take to pressurize.