Skygod
Posts: 211
Joined: Wed Sep 21, 2011 7:22 am

Re: Pi In Space!

Sun Mar 25, 2012 2:41 pm

You start talking with the CAA about a "controllable" device and you're into "Certificate of Airworthiness" declarations. A parachute is simply controlled with 2 controls. "Left' Right" and "Both". Hard Left or right, takes in you into a downward spin which is good for reducing altitude and keeping you close to your opening point. Both controls gives you 'flare' at landing time which slows your impact speed.

I'm sure that the BPA (British Parachute Association) would be willing to assist in arranging a suitable location for landing which is already controlled by 'skydivers in the air'. If not, I'd happily take that liason onbopard if nobody else has a contact with them

According to the CAA regulations, under the weight of 1kg, no issues, simply "up to you" (under the weight of a duck)

Sure it CAN be done, and it can be done relatively cheaply.

Getting control at lower altitude (c.20,000 feet) will be the thing. If a device can go to 100k feet and arrive back at it"s release point, I believe that this has never been done before.

Understanding wind shears at different levels is not a precise science though. I"ve been in freefall and in 60 seconds of descent, have travelled more than 3 miles in the opposite direction to ground winds. (No Fun)

poing
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Re: Pi In Space!

Sun Mar 25, 2012 3:00 pm

OK so what do you people think about this 'Space Mission' for the Pi:

1) Take the Pi to 'near space', an altitude > 20 km

2) Execute a mission (could be anything, like writing 'PI' in the sky with smoke, taking measurements, photographing landmarks for cartography etc.)

3) Land at the launch site

All this in some sort of competition (not necessarily being 'the first', but inside a time span of a year or so, possibly several winners), a fundraiser (donations, auction of the 'space Pi') and buying Pies for first- or second grade schools.

Skygod
Posts: 211
Joined: Wed Sep 21, 2011 7:22 am

Re: Pi In Space!

Sun Mar 25, 2012 3:35 pm

Getting to around 100,000 feet (30 km) is technologically quite simple and inexpensive, but getting much above that becomes tricky.

Landing at the launch site would be a 'first', but will need some good techies to write the software to control the direction of the descent.

Maintaining contact with the device at 30km distance would be a challenge as all that has happened to date seems to have been in getting a phone to generate GPS co-ordinates. (You need to use a different GPS standard as the US are paranoid about real GPS at high altitude – Rockets / ICBMs etc)

The CAA have no issue if it's a small payload (1kg would not be an issue)

Keeping full power for 3 hours at extremely low temperatures should not be an issue as foam or thermos technology will suffice.

Putting any logo on the balloon would be a nightmare as this would distort the expansion of the standard balloon and thereby limit its maximum altitude, so just make the 'payload' RPi 'branded'

GPIO programming for temperature, pressure sensors and sound would need to be written and pin connections resolved.

I'm of the belief that the whole thing (hardware wise) could be accomplished for just a few hundred dollars.

BTW, A similar project launched in Cambridge, actually ended up landing in Denmark

mayojs
Posts: 1
Joined: Tue Jun 26, 2012 6:00 am

Re: Pi In Space!

Tue Jun 26, 2012 6:25 am

There is indeed a whole community dedicated to High Altitude Ballooning.

Most launches have a dynamic GPS tracker generally consisting of a GPS module, Radiometrix 70cm transmitter and (generally) an Arduino module to run everything. This is where the PI could be used.

With the PI, it seems there is some issue with amount and capability of digital & analog IO pins which are used to decode the GPS data and pass to module for TX, as well as monitoring battery voltage, temp & pressure etc.

I've got both Arduino & PI now, and I'm sure it won't be long before someone get a PI in the Sky.

The record flight below used a tracking module which only weighed 40gm in its entirety:

http://www.daveakerman.com/?p=531

Check out also UK High Altitude Society (UKHAS) and IRC for lots of discussion and advice on modules

https://groups.google.com/group/ukhas

Lorian
Posts: 112
Joined: Sun Mar 11, 2012 10:09 am

Re: Pi In Space!

Tue Jun 26, 2012 7:28 am

mayojs wrote:With the PI, it seems there is some issue with amount and capability of digital & analog IO pins which are used to decode the GPS data and pass to module for TX, as well as monitoring battery voltage, temp & pressure etc.
Id have thought you could talk to the GPS using serial. Temperature and pressure can be done with one small SM IC. I believe Maxim have one. IF you wanted more I/O they also have I2C to GPIO expanders in their catalogue, but that would seem to be cheating.

I doubt it would be made to land at take-off location without having on-board propulsion.

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AndrewS
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Location: Cambridge, UK
Contact: Website

Re: Pi In Space!

Tue Jun 26, 2012 10:45 am

I was discussing this with my younger brother last night, and he suggested attaching a USB webcam and USB 3G broadband dongle to the Raspi, and having the Raspi post live pictures directly onto Facebook :D
No idea at what altitude the 3G would stop working though :?:

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Jim Manley
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Location: SillyCon Valley, California, and Powell, Wyoming, USA, plus The Universe
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Re: Pi In Space!

Wed Jun 27, 2012 2:10 am

Typical cell ranges are around 10 km/6 miles if you're in the cell transceiver's beam pattern. Unfortunately for aviation, that pattern is aimed slightly below parallel to the horizon to maximize signal power between tower transceivers and mobile cell devices. So, unless you can manage to bend a cell tower over to make some of the transceivers point up at your balloon (the cell companies hate what that happens - don't ask me how I know :twisted: ;) ), you're not going to get much in the way of data real-time. That's why most of these kinds of experiments record data on-board and retrieve it after the payload returns to the surface, or use a longer-wavelength radio (much heavier, needing a larger battery, radio, etc.).

I believe you need to include a radar reflector of a certain size/shape so that aircraft and air traffic controllers can track the payload and avoid collisions.
The best things in life aren't things ... but, a Pi comes pretty darned close! :D
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