Water recovery

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n27sb

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Sometimes it seems like if there was a bucket of water in the middle of a 100 acre cow pasture I could land in it. Some rockets prefer trees but here in Florida my rockets like water.
This is not a problem for fiberglass rockets but plays havok on electronics. This leads to a couple of questions.
Please do not confuse this post with other post in the past involving Illegal activities.

1 Any ideas on waterproofing altimeters.

2 What if you just plan to land in water

3 Are there any issues with launching low power rockets from a platform on a large lake.

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GalantVR41062

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Anything I launch in rocketry i need to make a effort for a safe flight, and recover ed everything I fly.

I have seen pictures of water launch platforms for lpr.

Water prof altimeter, that's a tricky on. The baro sensor for the altimeter that use that needs to see atmospheric pressure.

I think back to my electric RC car days and using a party balloon around said altimeter would be were I start.

~John
 

MClark

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Use an accelerometer altimeter in unvented compartment. But will just be single deployment.
I once saw a altimeter bay set up so when the main charge fired another charge pushed a plug into the vent hole. They were launching from a boat.
 

rocketman4h

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Back in the day I launched several rockets in the middle of a big lake. I had a few chase boats and I was on a pontoon boat. The launch pad was on an old dock piece floating on a huge inner tube. The early was a sweet no wind one. As soon as the sun came up we went out. All of the rockets were mid to high power. I did not use electronics. With the size of the lake and a few chase boats we were able to keep our eyes on the rockets. All landed in the water and floated. till they were picked up. On naughty rocket (an LOC MINI Mag) landed on dry ground. By the end of all the rockets 10 other boats had come out to help. What a great day that was!
 

n27sb

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Back in the day I launched several rockets in the middle of a big lake.
I have a pretty good dock on pontoons and chase boat. I was considering an Eggtimer Quantum in Test Mode as a launch controller. 5BEF5E6C-B8CD-4C5A-8E58-0A7266636F0D.png48C93614-322C-4F84-94EB-B82C631FE761.jpeg
 

skip_dye

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Sounds like you need a ebay with vent ports that close up after main deployment. That something a few servos could do.

Alan
 

rocketman4h

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what I did was have a 100 ft rope with a cable Attached for the launch. These day there are several way to remotely launch
 

Titan II

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see posts 30 and 32

 

n27sb

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1954 Feathercraft 12' Deluxe Runabout with a 1958 40hp Merc. Pretty Rare stuff.
 

Greg Furtman

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1954 Feathercraft 12' Deluxe Runabout with a 1958 40hp Merc. Pretty Rare stuff.
My Dad had a 14' aluminum fishing boat with a 20hp Merc. That thing moved pretty fast. As a kid we'd stay at some cabins on Bass Lake near Cohassett, MN. One year when we were there someone showed up with a home made hydroplane. My Dad put the Merc on it and at wide open about the only thing touching the water was the prop assembly. :headspinning:
 

Kelly

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There are PTFE (think 'Gore-Tex') membranes that are made to pass vapor but not water. I've seen some of these, for example, that are made into filters to prevent water passage. I would get some of this material (or an inline filter) and use it for the gas port.
Building the ebay with gaskets/orings on the ends might be another useful technique.

Here's the filters I'm thinking of: A little pricey, but you might find them cheaper:
 

n27sb

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So I think I have a solution. Had to mug a Party Clown 🤡 for a few balloons. Also robbed a 1/4 x 20 nylon bolt off my wifes chair. Cut the head off the bolt and line bored it on the lathe. This should waterproof the housing and allow barometric pressure to transfer. I think I can also run my GPS antenna through it.IMG_7752.JPGIMG_7753.JPGIMG_7754-1.JPGIMG_7754.JPGIMG_7755-1.JPGIMG_7755.JPGIMG_7756-1.JPGIMG_7756.JPG
 

caveduck

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You might want to do a bit of ground testing with a vacuum test chamber (poke around here for some inexpensive ideas). Any membrane will slow down the pressure equalization needed by a baro deployment altimeter. That will delay deployment somewhat beyond apogee...you'll need to know how much.
 

Greg Furtman

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You might want to do a bit of ground testing with a vacuum test chamber (poke around here for some inexpensive ideas). Any membrane will slow down the pressure equalization needed by a baro deployment altimeter. That will delay deployment somewhat beyond apogee...you'll need to know how much.
I bought a SterLite airtight storage container and drilled a 1/8" hole in the top. I had a small suction cup from my MightyVAc and hooked that up to my vacuum pump hose. Works great! :)
 

n27sb

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You might want to do a bit of ground testing with a vacuum test chamber (poke around here for some inexpensive ideas). Any membrane will slow down the pressure equalization needed by a baro deployment altimeter. That will delay deployment somewhat beyond apogee...you'll need to know how much.
Could be, but that was the reason for a bladder with a lot of surface area. It is also very flexible.

I bought a SterLite airtight storage container and drilled a 1/8" hole in the top. I had a small suction cup from my MightyVAc and hooked that up to my vacuum pump hose. Works great!
I do a similar setup with my foodsaver canister.
 

n27sb

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That will delay deployment somewhat beyond apogee...you'll need to know how much.
If you are right I think a late apogee will not be a problem because I break the rocket at the fin can.
 

Buckeye

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So I think I have a solution. Had to mug a Party Clown 🤡 for a few balloons. Also robbed a 1/4 x 20 nylon bolt off my wifes chair. Cut the head off the bolt and line bored it on the lathe. This should waterproof the housing and allow barometric pressure to transfer. I think I can also run my GPS antenna through it.View attachment 423810View attachment 423811View attachment 423812View attachment 423813View attachment 423814View attachment 423815View attachment 423816View attachment 423817
Not following. How does the altimeter sample atmospheric air pressure?
 

n27sb

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Not following. How does the altimeter sample atmospheric air pressure?
There is a hole line drilled lengthwise through the nylon bolt that the balloon is mounted to. The balloon can expand or contract with pressure changes allowing the canister to equalize to outside air pressure.
we used to do this on the altimeters in open cockpit aircraft to prevent moisture infiltration.


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Buckeye

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There is a hole line drilled lengthwise through the nylon bolt that the balloon is mounted to. The balloon can expand or contract with pressure changes allowing the canister to equalize to outside air pressure.
we used to do this on the altimeters in open cockpit aircraft to prevent moisture infiltration.
OK, I see. So, the balloon should inflate at high altitude. How much, and can your airframe accommodate that volume? As @caveduck said, any membrane will retard pressure equalization. I think main deployment is also at risk, and you only have a couple hundred feet to get the main chute open. Yeah, some vacuum chamber ground testing is needed to see the time lags. I'll be interested to know how your tests/flights work out.

FWIW, my launch sites have narrow drainage ditches running along the flight line, and rockets land in them more often than you would think. I landed 3 in there last season. However, they were recovered quickly without too much immersion. The altimeters were a little wet, but still work just fine after drying them out.
 

n27sb

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OK, I see. So, the balloon should inflate at high altitude. How much, and can your airframe accommodate that volume
It would be easy to calculate. Take the volume of the cylinder and apply Bernoulli's laws of expanding gas at a given altitude.

As @caveduck said, any membrane will retard pressure equalization
Not sure it applies here. The gas is not moving through a membrane It is just applying a pressure against the membrane. Unless the bladder inflates to the point of stretching I'm not sure if the altimeter would even know it's there. As the pressure outside the bladder drops the gas inside expands to equalize.

It will be fun to find out.
 

blackjack2564

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Simple.... use aquarium air hose. only 1 vent hole in bay. cut hole so hose fits perfect. I used round file and undersize hole filed to perfect fit. You must coil hose 1.5 to 2 full circles inside bay. I did it around perimeter. Done.

Coiled hose acts like a P-trap allowing only a tiny bit of water to enter, no way it can work its way around the coil and enter bay.
Be sure to foam nose cone so it floats. The rest of bay must be water tight. I did twist and tape power wire just electrical tape over hole and wire after powering on.

Build it, test without electronics, throw it your bathtub for 10-15 minutes and look for any leaks if water inside. You will see the air hose is not full of water. If leaking it most likely from BP's. I did stepped ones with O-rings. Can be as simple as scotch tape over the lip on each end, but the biggest leak problem is bulk plates on ends of bay.

So stupid simple and works flawlessly a plumber/rocketeer came up with this method years ago.

You neglect to mention what size airframe diameter your project is, or even what rocket. Best answers to questions require full data to begin with.
 
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