I finally worked out how to make the GMap thingy work to my whims, which means that I've designed a whole load of airfield circuits.
Major UK Airports (Completely unrealistic)
Gatwick Airport
With 15 turns over nearly three miles, it would be a pretty high-speed circuit in most places. I'm not really sure if it should be raced clockwise or counter-clockwise.
Glasgow Airport
With 2.7 miles of mostly flat-out circuit, this would probably be far too dangerous not to have far more chicanes than I've put in. All the same, I quite like its general shape, which is slightly similar to the Circuit Gilles Villeneuve.
Luton Airport
This is one of my favourites, with its long sweepers to the left and right at the start of the lap. I'm not too happy with the chicanes I put in though - they're a bit clunky and just sort of ruin the flow of the circuit. I should have left it with just the seven turns.
Stansted Airport
With about a dozen sharp turns in just over three miles, I kind of imagine this with metal barriers on either side and stock cars gunning their way between them. Would probably lead to a processional Grand Prix race, though, and Maldonado would crash into someone diving up the inside.
Airfield Circuits (Probably more realistic)
Bascombe Down
This MOD site was apparently host to numerous US black ops, but probably nothing as scandalous as that kneecap-shaped thing I put in the middle of the penultimate straight. I can only apologise for that.
Brize Norton
This is probably my favourite circuit so far - it looks like it would flow quite nicely, and it's quite a pretty shape. I'm not exactly sure if there are enough slow (or even medium) speed corners on there, but it would be pretty exciting to drive.
Honington
I like this circuit because it mixes some high-speed sections with other technical, twisty bits and funky chicanes. The RAF wouldn't like it because some roads would need widening and some buildings might be endangered.
Waddington
This one would need the most upgrades on its facilities - there's a lot of very narrow and/or rubbish paved road after mile three. The circuit itself seems to be a little bit new-Nurburgring-shaped.