...but I can't, for the life of me, figure out what.

I changed the default flight to one where the plane was sat in a parking space with its engine off, but all electrical/fuel switches on, just awaiting a mouse-click on the starter button. Now, when I create a flight with one of my add-on helicopters (Medco Huey or PaveHawk) they sit there with their rotors turning at almost 100%, but as soon as I pull up on the collective (ie. joystick throttle) the rpm's fall away, the helo doesn't do more than lurch, and it just sits there at about 50% rpm until the collective is bottomed again.

I know I must have left something switched off, but I've scanned every pixel of both helicopters' control panels in both 2D and VC views for a switch I've missed, but I can't find one. I've tried Ctrl-E to do an auto engine start but to no avail.

What have I missed? I just know it's going to be something painfully obvious...

*Looks up Ctrl-F4 in Commands list*

Ah. Oh.

That thudding noise you may have just heard was the dulcet sound of head meeting table. Many thanks!