We're omitting the good old British weather here me boy!
There's a bad crosswind in the stock mission.
Also there are two temperature controls to consider, oil and cylinder head.
The oil is in front of you on the orange gauges, but the cylinder head temperature is behind and to your right in a very stupid place above the fuel taps.
Set the game to have CEM and temp effects, start up engines and wait for the temps to get to 40 on the oil and just under 200 on the cyl heads. Keep opening and closing the cowl flaps, to keep cyl head temps down while the oil catches up.
Open your cowl flaps (radiators), hold it on the brakes until you're up to the gate on the throttles, about 65%, release the brakes and wait for a long time until your tail lifts. Give it a bit longer, pull back gently, and voila! You're in the air.
Immediately raise gear to cut down drag, gain some airspeed and at about 160mph cut back to zero boost and go to coarse pitch. When the the boost has increased to a steady value, reduce throttle to zero boost again. Trim for the climb.
Works for me anyway.
