So this morning (I know, I’m killing you guys that I don’t really dive in to all the sensors and weapons…it’s just time, time, time…responsibilities, 7-year old, family, house…etc…ya’ll know the drill…I’m not a 20-something single guy anymore) I wanted to check out the performance of the Harrier with different weight loads.
I don’t know what the specific land takeoff configurations are supposed to be - I suppose they are based on weight, runway length, and things like temperature. We’ll need a cheat sheet for that I’m guessing. Any-who, I loaded the Harrier with 20% fuel giving a very light weight of 15,529 lbs. versus the max weight of 31,085 lbs.
I went with the AUTO flap setting that showed 25 degrees and a nozzle setting of 50 degrees (I think that might be a standard “stop” for land short-takeoff…). I didn’t touch the trim, but I think it is supposed to be something like -2 perhaps…but I just left it as it. For a simple (non scientific) test, I set the same configuration for both takeoffs, did not hold brakes, and just advanced the throttle to 100% and let the plane fly itself out with no elevator input.
For the light weight of 15,529 lbs. we came off the ground after a ground roll of 669…at around 80 knots…
For the heavy weight test - I went with four external fuel tanks and a gun pod and had to bump internal fuel down a smidge to get close to the MTOW…settling in at 31,037 lbs. - same flap and nozzle configuration…
Are you guessing it was a longer takeoff roll? 
Sure enough…came off the ground at around 166 knots after a 8,263’ roll…
Obviously, both of those takeoff distances could be shorter with the use of some back pressure on the stick (and a headwind - I had that set to zero)…
EDIT - As a matter of fact, at the max weight, I tried feeding in some full aft elevator above around 120 and the plane “unstuck” around 150 knots (you could way over-rotate it if you kept that full aft elevator in though) at 5,650’…
