Multiple aircraft take off?

[Plt Off JRB Meaker]

Does anyone know how you get more than just two aircraft to take off in one go?

Normally if you have a Squadron and you get them to take off in FMB,they'll all take off,but they do it in pairs,not all at once,which is what I want to achieve.

Even If I could get three to take off at once I'd be happy.

I have seen it done in a lot of You Tube vids but have not yet succeeded in doing it myself.

If you look at any old Battle Of Britain newsreel there are more than just two aircraft taking off.

Any help or advise would be appreciated,thanks.