Same exact thing happened to me recently with my Super Sportster ARF. Luckily, the rubber stopper sticks out through a hole in the firewall into the engine compartment. The fuel all dumped out into the engine compartment in front of the firewall. I was about 60 feet up and upright when it dead-sticked. I brought it in without any problems and there was no fuel-soaked wood. I've since replaced the stock Great Planes tank with a Hayes.

Jesse