The Merlin should take 10 seconds to recover according to the RAF Pilots' Note General from 1943. Similar to the recover times posted for a naturally aspirated engine from Voyager's post...although the Merlin isn't naturally aspirated.

http://forum.1cpublishing.eu/showpos...2&postcount=92

Had this happen too once. The engine restarted however with throttle back and ignition (i key).

yeap i forgot to mention about the ignition
it would be great to use the ignition inside the cockpit and not some key commands:-P

All ignition is it getting the crank going, getting the spark plugs going, and making sure the engine has the right fuel/air mixture. If the prop is already turning, the alternator is still going, and the spark plugs are still sparking, once the fuel air mixture goes back to burnable, what else do you have to do to start the engine?