Enrique has it correct. That works out to around 1/2" or less in front of the main struts or, in other words, right on the forward bolts of the main retact units. Mine only needs a lot of back stick when taking off with full smoke tanks. Even so, and even with the speedbrake out, if you're the least bit fast and you twitch the elevator, it will likely lift off again. As a last resort, you might also try less stiff springs in the stuts to reduce the bounce action.