Hi Ollie, I have just received a catalogue from one of my suppliers, viz. Misco and in there there are some choices which are more portable. you could email them on
[email protected] and ask them about your requirements. I see Iomega do a 60 GB Mini Hard Drive for about £100 inc. It is USB powered (no mains required) and only weighs 3.5 oz. But, do you have a mobile computer? If you have you can transfer your pics via a USB card reader to it and then to the spare hdd. That's what I do. If not I suggest you buy more cards, and don't forget spare batteries. Good luck with the airshows, a part time interest of mine.