Hello from Neenah, WI

This forum is for new members to introduce themselves and tell us how they got started in water rocketry.
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Asupremeflight
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Hello from Neenah, WI

Post by Asupremeflight »

hello, my name is Chris and I am from Neenah,wi. I have been dabbling in water rocketry now since this past summer. I am realizing that the winters here play havoc on any attempts to splice bottles together. I was hoping to have a bunch put together for the spring but aside from building a humidity controlled room in my basement it is going to be slow goings.

I look forward to chatting it up with you guys and learning some things.

I figure if you are going to build them they might as well look nice. I like to build with themes. I am currently working on a Green Bay Packers themed rocket. It will be a single stage 9 ltr rocket. Hoping to get to 150 psi if not more.

I also dabble in pyro rockets as well.
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Re: Hello from Neenah, WI

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Asupremeflight wrote:hello, my name is Chris and I am from Neenah,wi. I have been dabbling in water rocketry now since this past summer. I am realizing that the winters here play havoc on any attempts to splice bottles together. I was hoping to have a bunch put together for the spring but aside from building a humidity controlled room in my basement it is going to be slow goings.

I look forward to chatting it up with you guys and learning some things.

I figure if you are going to build them they might as well look nice. I like to build with themes. I am currently working on a Green Bay Packers themed rocket. It will be a single stage 9 ltr rocket. Hoping to get to 150 psi if not more.

I also dabble in pyro rockets as well.
Welcome to the form Chris, :W

We look forward to your sharing any ideas that you have from your pyro experience.

Winter is so much fun. PU: when it comes to launching water rockets but you have the right idea of doing your construction now rather than when there is good launch weather.
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Re: Hello from Neenah, WI

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Asupremeflight wrote:hello, my name is Chris and I am from Neenah,wi. I have been dabbling in water rocketry now since this past summer. I am realizing that the winters here play havoc on any attempts to splice bottles together. I was hoping to have a bunch put together for the spring but aside from building a humidity controlled room in my basement it is going to be slow goings.

I look forward to chatting it up with you guys and learning some things.

I figure if you are going to build them they might as well look nice. I like to build with themes. I am currently working on a Green Bay Packers themed rocket. It will be a single stage 9 ltr rocket. Hoping to get to 150 psi if not more.

I also dabble in pyro rockets as well.
Hi Chris, and welcome to the forum!

The winter sure takes the fun out of launches, but we have really had no trouble doing building during the off season. What kinds of trouble have you been having with your splices that you made during the winter? We actually have had nicer results with lower humidity, because the PL Premium we splice with does not foam up so much when the air is dry.
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Asupremeflight
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Re: Hello from Neenah, WI

Post by Asupremeflight »

As far as the pyro goes it has just been some Estes kits, some scratch built rockets with Estes motors. Nothing crazy. The craziest I got was a scratch built Breast Cancer themed rocket for my Mother-in-law named "Survivor" with 2 pink parachutes and a long pink streamer.

And the issues I had with the splices was that the 2 I made both leaked pretty bad. I was using PL for the seals and the cover.The 1st splice I made in the summer worked just fine so I thought it must be the lack of humidity that caused the leaks. I just found a urethane based adhesive called Vulkem 116 for the seal (has anyone used this for the seals?) then PL for the cover and patch. I have not tested any yet. It takes forever to cure in dry conditions. It has a strange grainy texture so real curious how well it will work. I'll keep you informed.
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Re: Hello from Neenah, WI

Post by Asupremeflight »

In case anyone was wondering.
The new splices with the Vulkem 116 worked wonderfully. I tested the pressure up to 100 psi. (I did not want to go higher due to the cold) Not sure of the effects, if any, the cold would have. I am just playing it safe.
Question: if one can seal an FTC bulkhead with just PL and have it be leak free for the most part. Why all the extra steps needed for 2 ltr bottles? BTW I am using the aircommand way of splicing. (I.e. Seal, pet ring, then patch) I realize that if I want to put any major psi in the FTC I would most likely have to reinforce the bulkheads and the tank too.
Are there any other methods of splicing that use less steps or less glue?
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Re: Hello from Neenah, WI

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Asupremeflight wrote:In case anyone was wondering.
The new splices with the Vulkem 116 worked wonderfully. I tested the pressure up to 100 psi. (I did not want to go higher due to the cold) Not sure of the effects, if any, the cold would have. I am just playing it safe.
Question: if one can seal an FTC bulkhead with just PL and have it be leak free for the most part. Why all the extra steps needed for 2 ltr bottles? BTW I am using the aircommand way of splicing. (I.e. Seal, pet ring, then patch) I realize that if I want to put any major psi in the FTC I would most likely have to reinforce the bulkheads and the tank too.
Are there any other methods of splicing that use less steps or less glue?
There's really only one way to answer your question:

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Re: Hello from Neenah, WI

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Asupremeflight wrote:In case anyone was wondering.
The new splices with the Vulkem 116 worked wonderfully. I tested the pressure up to 100 psi. (I did not want to go higher due to the cold) Not sure of the effects, if any, the cold would have. I am just playing it safe.
Great to hear. Thanks for the info on the glue. I'm not sure how much effect the cold has on the glue, but I think the PET would be okay with the cold.
Asupremeflight wrote:Question: if one can seal an FTC bulkhead with just PL and have it be leak free for the most part. Why all the extra steps needed for 2 ltr bottles? BTW I am using the aircommand way of splicing. (I.e. Seal, pet ring, then patch) I realize that if I want to put any major psi in the FTC I would most likely have to reinforce the bulkheads and the tank too.
Are there any other methods of splicing that use less steps or less glue?
That's a very good question. It mostly comes down to the dimensions of the splice and how much force is exerted on it. There are two main directions of force acting on the splice. The circumferential (or hoop) and longitudinal. The hoop stress is related to the force within the walls of the bottle around the splice circumference. Because of its size a 2L bottle has almost 3 times the hoop stress compared to the much smaller FTC (assuming same wall thickness and internal pressure). This is one of the reasons high pressure hoses have small internal diameters. Because of this higher hoop stress we add the external sleeve on our bottle splices to reinfoce the splice and not have the glued section stretch as much.

The longitudinal force is the force trying to pull the two bottle ends apart. You can think of it as the internal pressure applied to the entire cross sectional area of the bottle/FTC. Now let's say you have a 2cm overlap in both splices that translates to around 6900mm2 of glued surface area for the 2L bottles and 2600mm2 for the FTC. Although the amount of glue holding the FTC splice is only about 40% that of the 2L bottle splice, at the same pressure the the force trying to pull the splice apart in the 2L bottle is almost 7x times bigger than in the FTC. (The 2L bottle has 7x the cross sectional area of FTC)

The upshot is that you can get away with a simple single overlap splices in FTC for the same pressures compared to the larger diameter bottles. As you mentioned, once you start subjecting FTC splices to the same forces you have in 2L bottles, you will likely need to do a bit more re-inforcing.

You can skip some of the steps in the splicing procedure to make it easier. The only reason we use a patch is because we don't have access to bottles with bigger diameters to make the sleeve. For our 1.25L splices we use sleeves made from 2L bottles and simply overlap them by about 1 inch. This prevents the need for a separate patch and you can glue the sleeve in one go. You can also skip all the steps about putting the tape on the sleeve and splices, we just do that to make the join neat with clean edges.

The reason for the two glues is that we found the PL premium in our humid environment tends to bubble and become porous and can cause the splices to leak. We found for some reason the 2L bottles leaked more often than the 1.25L bottles when using only PL premium. It sounds like the glue you found is a fairly good one. I'd be interest to hear to what pressures it will hold up to.

We've recently started using narrow sleeves on our 90mm splices and have found them to work well, improving the whole spliced-pair performance by about 10% (more volume/less weight), and using less glue. http://www.aircommandrockets.com/day120.htm#_splices

If you are only going to use low pressures for your rockets, and can get the PL premium to not bubble too much during curing, then you may be able to get away with just the overlap, and not need the sleeve. Give it a go with your glue, and then do some hydro tests to see if the splice holds up to your requirements. Perhaps try a longer overlap too. You always want to have a certain safety margin built into your splices. Test a couple of splices to bursting point, and then use your other splices at perhaps 70-80% of your burst pressure. It is also a good idea to do a non-destructive hydro test of your splice just a little past the operating pressure before you use it in your rocket.

Cheers

- George
http://www.AirCommandRockets.com
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Re: Hello from Neenah, WI

Post by Asupremeflight »

Great info there. Thank you. I am currently building 2 FTC rockets. One 4 ft and one 8 ft. Also constructing a 12 ltr "Packer" themed rocket with the new splices. I re-tooled my old launcher and made it so it can launch all of my rockets. FTC and the others with differing lengths of launch tubes. It also has a detachable launch rail for use with the Gardena attachment. It is a sweet set up. I can't wait till spring!

Do you think I should construct another launch tube assembly for the 8 ft FTC rocket? Or will the 4 ft tube suffice?
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Re: Hello from Neenah, WI

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Asupremeflight wrote:Great info there. Thank you. I am currently building 2 FTC rockets. One 4 ft and one 8 ft. Also constructing a 12 ltr "Packer" themed rocket with the new splices. I re-tooled my old launcher and made it so it can launch all of my rockets. FTC and the others with differing lengths of launch tubes. It also has a detachable launch rail for use with the Gardena attachment. It is a sweet set up. I can't wait till spring!

Do you think I should construct another launch tube assembly for the 8 ft FTC rocket? Or will the 4 ft tube suffice?
Your launcher sounds like a very nice set up. Unless you are going for absolutely max altitude I think the 4ft tube should be good enough. Run the rocket and launcher through a simulator (http://www.et.byu.edu/~wheeler/benchtop/sim.php) and see what performance difference you can expect with the longer launch tube. It may turn out it's worth your time constructing the longer launch tube. If you have both, fly some comparison flights and see if the simulator's predictions were right. :)

- George
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