Review of rules; question about “parts cost” vs. “cost of setup” and what counts as what (UPDATE in retrospect, it appears that they refer to the same thing and that we have a maximum cost of 250 for everything and everything above 150 costs us points).
We need to keep a wiki according to the rules. This includes a design document, bill of materials, and assembly instructions. We also need meeting minutes, photos, drawings, and side notes that include interesting facts and possibilities for modification of the design.
The intent is for the students, but we need a cool factor.
We resurrected the discussion on helium vs hydrogen. This time we established for certain that we will pursue hydrogen, and we’ll look into purchasing it instead of producing it because production would count against our costs and add complexity, and isn’t a viable option for easy reproducability. Additionally, the cost of helium will only rise in the near future, meaning the cost of this setup will rise accordingly, possibly to beyond the 250 goal.
Jesse found a 7′ balloon for $20, which is better than other balloons we had found so far.
We get points for every half pound of reduction, so what’s the minimum we can do?
What about an old smartphone? With a cheap-ish used phone and a pre-paid plan, we get the camera, battery, gps, and transmitter in a tiny package already. We can use the headphone for control of the tether, wrap it inside a foam enclosure with a window, and call it good. The phone is smaller and more efficient packaging of the components than we could build ourselves. The window may need to be coated with fog/frost protection. Cheap phones on swappa can be had for $50-$150 easily. Total weight could be under a pound easily.
This revelation adds all sorts of possibilities. A parachute may not be necessary as a well designed foam enclosure could protect the payload and prevent injury to anything on the ground. It would also speed up descent significantly. A hilarious conversation ensued. Choice quote:
“A foam lawn dart with fins.” “I have a jart in my garage… yeah, they’re illegal now.” “Now think of one _from space_.”
Everything can be built into the phone. Control, data collection and upload, recovery. We can use the GPS up to 60,000 feet and then use the accelerometer and time elapsed to calculate altitude beyond that. We can use the phone/headphone electronics as a platform for other sensor data as well. We can collect the battery, accelerometer, phone temperature, and not only record it but use that data to make intelligent automatic decisions.
If the phone gets too cold, it could run complex calculations so heat itself up, eliminating the need for handwarmers. If the battery is dying it can cut itself loose early so that it has enough battery to do recovery efforts. It can control automatic photo/video collection. It can upload telemetry in real time (assuming a connection).
We can build a web app for tracking all this data and show a map for easy retrieval.
Hardware is just going to be something that plugs into the headphone and listens for a signal on the left/right channel to control release of the balloon and possibly a parachute.
We should examine the possibility of a parachute which could deploy at a low altitude in case the descent is too fast and we want to ensure protection of the payload and the ground.
Foam construction will consist of two sections; the cage, which contains a window and a small opening for inserting the phone (which is then filled before launch), and the cone, which will provide the crash protection and absorb the energy. We will need fins for stability, and we can also incorporate the radar reflector into the fins. The cage could additionally contain a mirror in part of the window that allows the camera to see the balloon or down to earth.
Next week we need to have significant progress. We need to acquire a phone, foam, do initial tests of the foam for crash protection and insulation. Possibly test with liquid nitrogen and a spare blackberry. We also need to set up a wiki and start doing documentation.
Another choice quote:
“Terminal velocity is higher at higher altitude.” “Yeah, but we don’t care.”
“Should we be concerned about people stealing our idea?” “Is there a prize?” “No” “Then we don’t care.”
We discussed the software and the absolute minimums it must accomplish:
- Take pictures
- Report position to somewhere else.
Both of these can be accomplished with existing apps already.
Possible names for the web site:
We agreed to think on it.
People took assignments/responsibility for the different aspects:
- Lift/Balloon – Adam & Alex
- Hydrogen – Alex & Mike
- Filling/release mechanism – Alex
- Line/tether – Adam
- balloon release mechanism – Micah
- electronics – Micah & Mike
- optional parachute – Bob & Jesse
- cage/foam insulation/window and testing – Jesse & Micah
- fins/reflector – Jesse
- impact/crash zone/retro rockets. – Jesse & Micah
- decoration/bumper stickers – Everyone
- heat -
- phone acquisition – Isaac
- app – Bob & Isaac
- wiki/web site – Bob
- Register with hackersinspace – Bob