Very, very clever. I'm surprised that altitude activated switches aren't available off the shelf.
Followers of our Paper Aircraft Released Into Space (PARIS) project will be aware that our first attempt to put together a pressure-operated Vulture 1 release mechanism didn't exactly go according to plan. For those of you who're not up to speed on this vital mission component, we should explain that it's the device which will …
So if the tube is only for structural purposes and not to act as a pressure vessle why not get the big drill out and perforate it? should save many grams doing that. Additonally why not use a carbon/glass fibre push rod? An Angleing store or a Kite shop will have what you need.
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Look at Julianh's post, third from the top:
While GPS in principle can do the trick, the civilian GPS units that will be used are limited to about the altitude PARIS will need... and that would be sketchy.
Besides, as has been noted, this is way more garden-shed and therefore much much cooler.
...coil the tube up into a spring shape for space savings? It'll still expand inside whatever drum or coiled tube you put it in. Also I'll second Parax; that PVC tube can probably have more than 50% of its mass drilled out and still retain enough shape and strength to function. That's if you don't decide to go posh and use a glass or carbon fibre tube (or old fishing rod).
If you want something super-light and you think you can form it around something (dowel and some grease paper possibly), model shops will sell a kit of thin glass fibre sheets and resin that's designed for constructing helicopter bodies and suchlike. It'd take a bit of work and sandpaper, but you would end up with a very lightweight fibreglass tube that can be as thin as its task allows. It probably wouldn't blow the budget either - I think I remember it being a tenner or so for about 4 1m/sq sheets plus bottles of thin adhesive/hardener.
Last but not least, I hope you can get a couple of nice telescopes to film this thing through. That or let any commentards know where and when with enough notice that they can bring theirs. This is daftness on a scale of painting a Robin Reliant up as a radio-controlled space shuttle and sending it heavenward on the most powerful non-commercial rocket built in Europe. It'd be a shame to not have a video of the fun.
The rubber tube is a stroke of sheer mechanical genius and much is to be applauded for the solution but the idea of using the GPS or even a reading from a barometric pressure sensor to determine altitude does have some useful advantages in a contingency situation.
Say for example, the balloon bursts for some reason without getting to the planned altitude, the onboard CPU will detect the sudden drop in altitude and release the payload before falling too far.
I would say it's better to release at a lower altitude, than to watch it fall and crash.
But not a drop in PARIS
Where did they mention "water"? Not sure it's mentioned anywhere. The word you're looking for is "liquid", specifically antifreeze.
Even ignoring that, if they were to use water, it's boiling point at 20,000m is about 30C by my reckoning. But this is dependent on the PRESSURE, not the height. The tube the water is in is coincidentally, sealed, effectively keeping it at ground level pressure, meaning the boiling point stays at a steamy (pun intended) 100C.
It's the pressure differential that causes the mechanism to work.
... isn't that rather big?
What about using the insides of an aeneroid barometer and a microswitch?
It is good that you thought of freezing, I would suggest using 100% antifreeze as the liquid. But there is one other problem you probably overlooked: rubber solidifies and becomes less flexible at extremely low temperatures. The expanding hose might crack instead of expanding. I suggest you test this apparatus in a hyperbaric chamber, AND at low temps.
First Antifreeze! Ethylene Glycol 100% solution frezes at -12C! when mixed with water (70%EG) you can achieve -60C (is that cold enough?) Anyway DO NOT USE 100% !
Anyway in this situation pure 100% methanol (-95C) would probably be the best Solution (pun intended no coat) alternativly use solid unexpandable granuals (6mm Plastic Airsoft BB balls? - make sure they are VERY dry) with the required airspace.(this only needs to expand once, and not contract.)
Second Rubber! This is a military grade Oxygen Hose! the same as those you would find in U2 - the reason this thing is so big is because they ARE using the correct Rubber!
*Nobody* knew enough to take some smooth nickel plated brass rod and a die and make a suitable threaded piece?
What the hell is on the school curricula these days? (Latin wasn't on mine, but over the years the basic engineering they taught me in metalwork has proved of more use than a dead language).
Christ on a bike, so much for England, the cradle of engineering. This is what a "point, click, ship" culture gets you.
What the hell are you on about?
The earliest known engineer was Imhotep of Egypt, ca. 2700 BCE. After that, Chinese, Indian, Egyptian, Greek and Roman, Aztec, Mayan and Incan engineering works are well documented; and after the fall of Rome, Abū al-’Iz Ibn Ismā’īl ibn al-Razāz al-Jazarī, an Arab engineer, created a wide variety of devices, many still in use today — including a catchment device used in clocks, and a reciprocating water pump for irrigation purposes.
So, um, *England* the cradle of engineering? Are you on crack?
Whilst others have tinkered only one really succeded. A cradle is for nuturing growth after the birth not for conception.
oh and perhaps you mean escapement not catchment.
Education these days really is piss poor. (as I beleive the OP was suggesting) Threading a brass rod by hand would only take 10 minutes but they don't sell Taps and Dies in B&Q!
Do you even need the release mechanism to be inside the aircraft? That's a lot of weight saved if you were to, say, use an eye-hook or something on the back to pass a loop of thread through. Use some kind of double tubing to stop the string from tangling with itself as it goes down from the release mechanism, through the eye-hook and back up. On release, one end of the string is released/cut/burned through/whatever. You'd lose the release mechanism but have an aircraft that's a lot lighter.
Or alternately, attach a parachute and transponder to the release mechanism as well and have it find its own way down. Rubber Tubing Released Into Space doesn't have quite the same ring to it though.
... for the glass syringe idea then. I thought it was really elegant, simple, robust, light and small, and some vacuum grease would have solved both the leak and stiction problems (the one you used here would most probably have worked, did you test that?).
But at least with with this latter design you can use duct tape! So please, do.
this is a paper aeroplane fcs. whilst this kit works as an actuator, on this scale it could be used to drop a humvee lands sakes it must weigh round a pound. what about a simple trip operated by a squash ball ( or sim ) housed in a cardboard tube/chamber. ounces instead of lbs.
if the caf at the lab was any good ?.....
otherwise PARIS is a jolly good job that's needed doing forever and can't wait for the telemetric files
That El Reg has not adopted an IT solution to this problem. A simple GPS + computer hooked up to your release mechanism could do this instead of the Heath Robinson system proposed. On top of that you could probably use the waste heat from the CPU to keep the release mechanism defrosted if needed.
If you really wanted to demonstrate ingenuity, how about jailbreaking an iPhone or Android phone, getting it to report its location periodically or on demand, and then accepting/generating a release command through its USB connector?
"A simple GPS + computer hooked up to your release mechanism could do this"
No, it very much couldn't.
"how about jailbreaking an iPhone or Android phone"
How about NO? That wouldn't be ingenuity, that would be LOLkiddie showoff. Plus, it wouldn't work anyway.
Bear in mind that the balloon won't go straight up. If you've ever played with or made your own sky lanterns, you'll know that the balloon could quickly find itself ten miles along the horizontal for every thousand feet of altitude, and that's before it gets to jetstream altitudes. Now think of how much a couple of hundred miles of wire will weigh and the probability of part of it snapping. Also, what's going to happen to a couple of hundred miles of released monofilament under the influence of gravity and wind?
Though the idea of holding a balloon and paper aeroplane on the end of a fantastically long fishing line like a perverse high-altitude kite does amuse.
PARIS it/her/self will go down ok (doesn't she always? fnar fnar), but what about the remains of balloon with a couple of hundred grams of steel & plastic?
How fast will it be going when it clocks you on the head?
Also: I know the chances are unlikely, but what if the London-to-NY A380 sucks this through an engine?
When I used to fly RC gliders, I NEVER put any identifying details on it - loss of radio gear better than being identified after pranging into someone's house/car/pet/small offspring.
OK, that was three questions.