Originally Posted by OVERTALK
Elevator full down (i.e. stick full forward) will only effectively weight transfer onto the nosewheel, leading to "wheel-barrowing" (a condition of directional instability). It won't, by any useful measure, decrease the wing's AoA. Why? Think of a depressed oleo as only being able to soak up shock i.e. weight-bearing oleos are effectively incompressible to flight-control inputs - therefore fully-down elevator will just load up the nosewheel. It won't depress the nose oleo appreciably more, nor take any angle-of-attack off the wings. ....
Sorry, but this is nonsense. ANY increase in the load on an oleo will cause it to further compress, unless it is ALREADY fully compressed. For very good reasons relating to the risk of internal damage and loss of shock-absorbing capacity, designers will include sufficient margin that under any kind of foreseeable operation the oleos - all of them - are NOT fully compressed.
Therefore, back stick WILL raise the nose (by compressing the mains and unloading the nose) and forward stick WILL lower the nose (by compressing the nosegear and unloading the mains). It's simple physics, no magic about it.
The QUESTION which is type dependent is whether the directly created mainwheel download by back-stick will or will not outweigh the unloading caused by increased AoA. It's type dependent and CG dependent and technique dependent and...and...and...
it certainly is not a given that backstick is the preferred option.
You will note that internationally well-known Experimental Test-pilot John Farley came out in support of the backstick braking technique but was rudely rebuffed, essentially in mid-post, by one of those who cannot accept the practical facts..... and who instead waxed on with ever-confusing hypotheticals. Backstick braking is a proven effective stopping technique. Unfortunately it's not yet been automated and, because it is a dynamic process, it is easily misunderstood. Those who normally oppose change have been well represented on this thread and have used quite illogical reasoning in an attempt to deny its effectiveness and conjure up fanciful possible dangers.
I for one prefer a soundly based theory to hero-worship - with all due regard to JF, he cannot possibly know the characteristics of every type and I will repeat once again for those who missed it:
THE SPECIFIC ADVICE TO CREWS FOR MY COMPANY'S MAIN PASSENGER AIRCRAFT IS PROGRESSIVE FORWARD STICK DURING BRAKING. This is based upon flight test experience of the aircraft, not upon a theory. I would hate one of our crews to decide to go against the advice of Test Pilots who flew our certification testing and try out some technique of their own.
And it doesn't matter how 'automated' the process is: ANY transference of load from nose to main MUST raise the nose. The less load you transfer, the less the nose will raise and the less use also will be the backstick method....