Its kinda hard getting your hear around it but it happens on cars and motorcycles too at the limit with some types. When you are on the as coming out of a corner in a rear wheel drive rally car you are steering right on a left hand corner but the steering input is just to keep the angle of the car correct for powering out.
P-51 fuselage fuel tank (1 Viewer)
- Thread starter Barrett
- Start date
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Thank You for posting those pages Bill,
Yes, plate II-1 is Static Stability and shows push or pull forces on the control stick for maintaining level flight with speed deviations away from level flight trimmed at 100mph, at different
CG, %MAC, as shown.
Plate II-1 cont'd shows a simple illustration of linear stick force per G at varying CG, %MAC.
Neither of these plates appear to represent the P-51 data.
Going back to the 4-43-23-1 Eglin test report of the P-51B aircraft with rear 85gal tank, we can see that the results were much more complicated. Although the results are not presented in a detailed or graphic way, we can read in section 6.c that, with a full rear tank, stick force reversal occurred above accelerations of between 3 to 5g. Presumably, below 3 to 5g the
stick force response was normal and, in fact, the criticism of handling only really seems to be aimed at tight turns and pull-outs. Going back to plate II-1 cont'd, we can see that stick force per G is shown there as a straight relationship, but here the relationship seems to have changed at about 3g. We know that the full rear tank is taking the CG, %MAC some 1.8" to 2.7" beyond it's normal rear limit. My guess is that the limitations and characteristics of the pitch control system pretty much bounded the normal 102" CG, %MAC limit, and so this extra weight so far aft was just causing the undesirable handling that is described. Fortunately, careful operation of the aircraft and crew training allowed the use of this great increase in capability.
Thanks for the extra info.
Eng
Yes, plate II-1 is Static Stability and shows push or pull forces on the control stick for maintaining level flight with speed deviations away from level flight trimmed at 100mph, at different
CG, %MAC, as shown.
Plate II-1 cont'd shows a simple illustration of linear stick force per G at varying CG, %MAC.
Neither of these plates appear to represent the P-51 data.
Going back to the 4-43-23-1 Eglin test report of the P-51B aircraft with rear 85gal tank, we can see that the results were much more complicated. Although the results are not presented in a detailed or graphic way, we can read in section 6.c that, with a full rear tank, stick force reversal occurred above accelerations of between 3 to 5g. Presumably, below 3 to 5g the
stick force response was normal and, in fact, the criticism of handling only really seems to be aimed at tight turns and pull-outs. Going back to plate II-1 cont'd, we can see that stick force per G is shown there as a straight relationship, but here the relationship seems to have changed at about 3g. We know that the full rear tank is taking the CG, %MAC some 1.8" to 2.7" beyond it's normal rear limit. My guess is that the limitations and characteristics of the pitch control system pretty much bounded the normal 102" CG, %MAC limit, and so this extra weight so far aft was just causing the undesirable handling that is described. Fortunately, careful operation of the aircraft and crew training allowed the use of this great increase in capability.
Thanks for the extra info.
Eng
While this will probably be wrong, and overly simplified: Is this almost like that the tail wants to keep going forward in a turn on momentum, and you end up doing a donut?
*scratches head* Is this something to do with neutral stability (no AoA change with speed when AoA is increased), deceleration (which drives up AoA), and potential effects of the tractor-prop on stability?
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