100% reliable parachute deployment

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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The Sky Dart
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Re: 100% reliable parachute deployment

Post by The Sky Dart »

Very good design, but the is one potential issue. In version shown in the video there is a very little delay between the end of the thrust phase and the moment of the recovery system deployment. Usually, if thrust is sufficient to accelerate a rocket to a speed necessary for the stable flight, the rocket will coast up for some time after its motor is off (pressure inside the rocket is equal to the outside pressure in case of a water rocket). There should be a few seconds delay to allow parachute deployment at the apogee.
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thampson
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Re: 100% reliable parachute deployment

Post by thampson »

Nice work Frank .. well done. I can see uses for it for my water rocket car as well .. maybe a delayed second stage booster :)

keep up the good work
-todd-
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Frank
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Re: 100% reliable parachute deployment

Post by Frank »

The Sky Dart wrote:Very good design, but the is one potential issue. In version shown in the video there is a very little delay between the end of the thrust phase and the moment of the recovery system deployment. Usually, if thrust is sufficient to accelerate a rocket to a speed necessary for the stable flight, the rocket will coast up for some time after its motor is off (pressure inside the rocket is equal to the outside pressure in case of a water rocket). There should be a few seconds delay to allow parachute deployment at the apogee.
Ahhh...but that has been thought of! The inlet/outlet for the air into the bicycle tire is restricted, and a delay (not infinite in span, but more than enough) can be dialed into the deployment scheme. Initially I used a slightly drilled out spray bottle nozzle, but as the device got smaller and the volume in the tire got smaller, I stopped drilling out the spray nozzle, leaving the air to leak out the equivalent of a pinhole! Use of the spray bottle nozzle is depicted in some of the earlier pictures, and this latest incarnation, seen here (its green). Delay testing can be done right on the bench.

There have been MANY changes in materials and methods as this has evolved. I no longer use zip ties to secure the tire piece. I use VERY tight wrappings of twine. These I cover with an additional short piece of tire tube.

Best,

Frank
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U.S. Water Rockets1
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Re: 100% reliable parachute deployment

Post by U.S. Water Rockets1 »

Frank wrote:Hey, guys & gals:

The miniaturization of this bladder controlled parachute deployment system is really progressing nicely. Here's my latest, lightest, most reliable version yet! This puppy is ready to FLY!!! Every test has proven its reliability and has been tested to 100 PSI. Simple and cheap to construct, no electronic components, just a couple of pieces of cheap PVC, couple of inches of bicycle tire inner tube and a cut up rubber band will propel your nose cone off with authority at the end of the thrust phase, every time! Weighs only a handful of grams and with some outlet obstruction, can delay deployment of the parachute. The delay can be dialed in on the bench, without need to fly it.

Here it is in the inflated state (VERY low pressure) without the PVC bearing tube to illustrate the way in which the tire balloons out to secure the bearing tube built into the nose cone. I hope several folk will build this and employ it to deploy their chutes. If you do, kindly provide your feedback and/or videos to this thread.

Best regards to all,

Frank S.
Hey Frank, did you know there was a guy in the netherlands that built a kevlar wrapped water rocket that used a bicycle inner tube bladder with a small hole in it to control his deploy? It looks like a very similar idea to yours only yours is a lot more refined and much lighter. It sure looks like you have designed "the next big thing" in deploy systems. Your concept is hands down easier to make and more reliable than a Tomy Timer.

We're going to refer to your idea as our most recommended method for the new water rocket enthusiast. That looks like a really winning design. Hopefully you can report back on multiple successful flights.
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Deckard
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Re: 100% reliable parachute deployment

Post by Deckard »

After finding this thread I had to join to see the photos to find out how similar my design is to yours and also to report on my progress.

Although saying design is far to strong a word as my intention was to make a stager based on a garden hose connector after finding pvc waste pipes are really handy sizes and having a euraka moment about a bicycle inner tube. I'm now considering I must of come across this thread a few months ago and forgot about it, but left a few thoughts in my head.

My stager would be attached to the first stage with a robinson couple and triggered by the loss of pressure allowing a inner tube to deflate releasing it's grip on a pipe which is then propelled by rubber bands.

I "thought" of the deployment device when I was testing the princple of inflating the inner tube over a piece of overflow pipe in exactly the same way in frank's latest design. I then had a working device with the flaw of that it would deploy the parachute straight after the thrust ended which would only be a few meters of the ground so I returned to finishing my stager.

After a few failed attempts of making a one vavle to allow the air from stage 1 to stage 2 while stopping the water going from stage 2 to stage 1 I decided a simple pin hole would do the job. I did a dry test inside, not generally a good idea even if I am only using low pressures. So I was keeping a firm grip on the second stage to prevent ceiling damage when I release the pressure from stage 1 I noticed how long stage 2 kept pressure. A second euraka moment and I could get a useful delay with the deployment device although a pin hole can be a bit big just the end of a pin or needle is enough.

I'm fully expecting my first attempts to fail at higher pressures but I wanted to get a chance to fly it first. Even more so after reading about Frank's tests. I decided to use some 700ml bottles and low pressures since I don't want much height so I can have a decent chance to film it anyway. The small bottles did give me a bit of a problem with space with the parachute.

So today finding it's going to be windy for the next few days and it not being today and with the light failing I went out with my Casio EX-FS10. I couldn't stop myself buying it when I discovered I could afford something with such frame rates :o

So here are the results which are mixed. Pressure 40psi filmed at 210fps

[youtube][/youtube]

I'll post more details of my device.
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Deckard
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Re: 100% reliable parachute deployment

Post by Deckard »

Deckard wrote: My stager would be attached to the first stage with a robinson couple and triggered by the loss of pressure allowing a inner tube to deflate releasing it's grip on a pipe which is then propelled by rubber bands.
Ok that's a description of the deployment device, although apart from the last 4 words it also the first part of the description for my stager mark I. For mark II I will be trying rubber bands.
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U.S. Water Rockets1
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Re: 100% reliable parachute deployment

Post by U.S. Water Rockets1 »

Deckard wrote:After finding this thread I had to join to see the photos to find out how similar my design is to yours and also to report on my progress.

Although saying design is far to strong a word as my intention was to make a stager based on a garden hose connector after finding pvc waste pipes are really handy sizes and having a euraka moment about a bicycle inner tube. I'm now considering I must of come across this thread a few months ago and forgot about it, but left a few thoughts in my head.

My stager would be attached to the first stage with a robinson couple and triggered by the loss of pressure allowing a inner tube to deflate releasing it's grip on a pipe which is then propelled by rubber bands.

I "thought" of the deployment device when I was testing the princple of inflating the inner tube over a piece of overflow pipe in exactly the same way in frank's latest design. I then had a working device with the flaw of that it would deploy the parachute straight after the thrust ended which would only be a few meters of the ground so I returned to finishing my stager.

After a few failed attempts of making a one vavle to allow the air from stage 1 to stage 2 while stopping the water going from stage 2 to stage 1 I decided a simple pin hole would do the job. I did a dry test inside, not generally a good idea even if I am only using low pressures. So I was keeping a firm grip on the second stage to prevent ceiling damage when I release the pressure from stage 1 I noticed how long stage 2 kept pressure. A second euraka moment and I could get a useful delay with the deployment device although a pin hole can be a bit big just the end of a pin or needle is enough.

I'm fully expecting my first attempts to fail at higher pressures but I wanted to get a chance to fly it first. Even more so after reading about Frank's tests. I decided to use some 700ml bottles and low pressures since I don't want much height so I can have a decent chance to film it anyway. The small bottles did give me a bit of a problem with space with the parachute.

So today finding it's going to be windy for the next few days and it not being today and with the light failing I went out with my Casio EX-FS10. I couldn't stop myself buying it when I discovered I could afford something with such frame rates :o

So here are the results which are mixed. Pressure 40psi filmed at 210fps

[youtube][/youtube]

I'll post more details of my device.
The light is certainly fading fast this time of the year. Soon there will be snow on the ground and launching will be much more difficult.

The low light is the only problem for the casio cameras. It is a shame that they need so much bright light to take high speed video. We find they don't work really well on cloudy overcast days. If the sun is out, they work wonderfully. Thanks for sharing the video.
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Deckard
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Re: 100% reliable parachute deployment

Post by Deckard »

I've had a chance to use the casio on a sunny day and I was very impressed with the footage.

Here's a blurry photo of my version of Frank's idea, I glued the ends of the tyre inner tube to the overflow pipe then reinforced it by wrapping wire over the ends covered with bits of inner tube. Necks of bottles are glue to either end. So one end is sealed by a bottle top lid and the other is attached to a bottle top robinson coupled to the rocket. A plug is put in the robinson couple to restrict the airflow. The outer pipe is 40mm waste pipe.

I think if I made more room for the parachute it would be more successful.
Photo of deployment device.
Photo of deployment device.
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Newtowrockets
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Re: 100% reliable parachute deployment

Post by Newtowrockets »

Hello Frank,

I have a few questions about your latest version of your deployment system:
1) How do you hold the nosecone of the rocket while pressurizing?
2) What do you use to plug the end of the bicycle inner tube, and how did you attach it to the bottle cap?
3) I have 700*38C bicycle inner tube, do you think it will work?

I decided to use this deployment system for my new rocket since it is simple and I have most of the materials for it, and appears to be very reliable.

Thank you,

William
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Re: 100% reliable parachute deployment

Post by Newtowrockets »

Hello Frank,

Sorry for so many questions, but also what exactly are the materials you used for the deployment system?
Also what is the green spray nozzle for, to reduce the rate at which the air leaves the inner tube?

Thank you,
William
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Re: 100% reliable parachute deployment

Post by T86157 »

How did you seal both ends of the tube (robinson coupler side and pvc open side)? What kind of plug did you use? I read the whole thread twice before a light went off in my head on how your deployment system works. Now, it's the technical stuff on assembly that I'm wondering about...

If I use a random piece of plastic, wood or metal rod, I could use PL Premium adhesive for the pvc open side. If it is a solid pvc rod, which I have no idea what hardware store would sell that, then I would use pvc cement.

As far as the robinson coupler side.... not sure about the pvc pipe to the robinson coupler bottle cap attachment. Maybe PL Premium as well? Sand both edges up a bit to give it some extra hold.
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T86157
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Re: 100% reliable parachute deployment

Post by T86157 »

Frank wrote:
To tell the truth, I expect a major overhaul of this concept to make it far lighter, smaller, simpler, safer, and WAY stronger. Hint: It will use a short section of capped PVC (maybe 2"- 3" tall) drilled HORIZONTALLY at the very top. A short section of BICYCLE tire will be the bladder. Two turned pieces of wood (cut of sections of a hardwood dowel with a "waist" to allow the tire to be secured) just smaller than the ID of the PVC tube will enclose the end of the tire material and be the "bearing plate" at one end, and the means to introduce air at the other. If you prefer a spring device, a spring-loaded, very short piece of skewer sick can be passed thru the cap horizontally and act like a "pull-pin" to release whatever mechanism deploys the chute. In the alternative, a rubber-band can be directly passed thru the holes (use and keep attached to it a short piece of string to re-arm in seconds) and in each instance, when the pressure drops, the "pin" is pulled or the rubber band is release from the crush of the wood bearing block and viola, parachute deployment.

So...don't anyone fret over the current implementation, materials, and degree of difficulty in construction. Far simpler, smaller, and more robust versions are on the way which will leave much more room for a chute and other requisite payload! :cl:

Again, best to all.

Frank S.
Nevermind about the materials for the assembly. Looks like that was posted. It sounds like the wooden dowels, however, are not even adhered to the pvc but rather the pvc and the wood is sandwiching the rubber tube. Still unsure of the robinson coupler side, however.

I would like to try this deployment method on a different rocket but with a spring... not sure I could make an airtight hole through the cap to allow the shaft to contract. I would have to do more thinking on this.