Skunk is the project of building a box around the helium flowmeter for precisely filling balloons. It will:

• Have a menu allowing the user to set a volume of helium to pump or a mass of balloon to lift (Integrating the balloon burst spreadsheet from http://cuspaceflight.soc.srcf.net/calc/)
• Have a screen (2×16 LCD with LED backlight) displaying helium pumped so far, target amount of helium and current flowrate
• Have a knob for adjusting helium flowrate
• Have a sexy box with wheels including the (massive) batteries

Current status: Cillian has bought a significant proportion of the electronics parts and is playing with them.

• Gas connections are all hooked up and (basically) sorted! Need testing though
• Box is bought and gas stuff is largely fitted. Gas connections need panel mounting
• Electronics needs boxing and proper cables/connectors adding

Things what need doing:

• Hardware
  • Put everything in the sexy box
• Electronics
  • Give everything proper cables/connectors
• Software. ALL the software

Random plans and pondering:

• Arduino apparently has an upper limit of supply voltage of 20V, the battery supply is nominally 24V and the buzzer takes 12V - I figure take a lead off between the batteries and give that 12V supply to the arduino/buzzer and the full 24V just to the flowmeter with a common ground. I figure the power to the arduino and piezo is small enough compared to the 350mA flowmeter that the difference in drain between the batteries should be negligible.
• Cheap keypads with numbers 0-9, * and # - I figure that's sufficient for a menu system with # as yes/enter/ok/start pumping, * as cancel/back/pause
• Keypad comes pre-matrixed, arduino mega should certainly have enough pins for LCD, keypad, serial and other gubbins. An uno would probably need something more fancy and/or the serial display.
• Arduino box needs to be at least: 110 x 60 x 40. Cillian will go to maplin and poke some boxes.