Rejected Takeoff
SuperRanger: It is a shame that we only practice aborts once per year in the sim.
However, if your preflight "flow" tells you to check the spoilers (while noticing fluc. in hydraulic pressures) and then to push the throttles forward, thereby retracting the gnd spoilers, you can modify this just a little bit and practice the motions of an abort each time you do the long preflight checklist, while pushing on the brake pedals. Just don't forget to reset the parking brakes!
This practice helps me in the sim, because the abort is less of a radical change to the normal landing where we almost never need to lift the spoiler handle-unless the FO makes a very smooth landing with some float and the wheels barely kisss the runway (2 main wheels spin-up to activate, before ground shift happens). They mostly make better landings than I do.
However, if your preflight "flow" tells you to check the spoilers (while noticing fluc. in hydraulic pressures) and then to push the throttles forward, thereby retracting the gnd spoilers, you can modify this just a little bit and practice the motions of an abort each time you do the long preflight checklist, while pushing on the brake pedals. Just don't forget to reset the parking brakes!
This practice helps me in the sim, because the abort is less of a radical change to the normal landing where we almost never need to lift the spoiler handle-unless the FO makes a very smooth landing with some float and the wheels barely kisss the runway (2 main wheels spin-up to activate, before ground shift happens). They mostly make better landings than I do.
Dolly737's data point shows the effect of spoilers at 135 kt, but it does not give the deck angle (which of course is of more interest with the spoilers down).
As airspeed reduces to headwind the drag contribution from the spoilers (and any lift) reduces with the square of the airspeed; so, to completely assess the effect of spoilers, one has to do an integration and I've been out of school too long to think of doing that.
But I do have to say that I have seen the effect of spoilers at low speed at a glider field. One day somebody landed a Pilatus, forgot the spoilers and came within a few yards of the fence at the end.
So if spoilers make a big difference to the ground roll of a glider between 35 and 5 kt, they must also make a significant contribution on the big iron at low speed.
As airspeed reduces to headwind the drag contribution from the spoilers (and any lift) reduces with the square of the airspeed; so, to completely assess the effect of spoilers, one has to do an integration and I've been out of school too long to think of doing that.
But I do have to say that I have seen the effect of spoilers at low speed at a glider field. One day somebody landed a Pilatus, forgot the spoilers and came within a few yards of the fence at the end.
So if spoilers make a big difference to the ground roll of a glider between 35 and 5 kt, they must also make a significant contribution on the big iron at low speed.
Moderator
Considering glider vs big bird ... consider the comparative differences in
(a) spoiler frontal area and contribution to total airframe drag
(b) aircraft mass
and the usual observations are readily explained ...
The value of spoilers on the sailplane is seen in reverse .. very clearly ... on the odd occasion when the glider launches with the boards cracked and the tug pilot then has his work cut out and, perhaps, an unpleasant decision to make ...
(a) spoiler frontal area and contribution to total airframe drag
(b) aircraft mass
and the usual observations are readily explained ...
The value of spoilers on the sailplane is seen in reverse .. very clearly ... on the odd occasion when the glider launches with the boards cracked and the tug pilot then has his work cut out and, perhaps, an unpleasant decision to make ...
Join Date: Feb 2003
Location: Zanzi's Bar
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On B767 "RTO" setting on autobrk selector is equal to "max manual braking" Boeing recomends not to disengage "RTO" IF IT IS DOING a good job coz it copes better with braking than the Best human can do and reduces the workload in a RTO situation. So the Best human can focus on things like maintaining the centerline... 
