Hello Hawk
The truth is I don't know where that 1.96g comes from.
As far as I know, gs come from Lift. If one airplane has less ability to increase its lift than other airplane, all other factors remaining constant (weight, speed...) it follows that this airplane has less manoeuverability.
Please I would like to see how you get the 1.96 g in detail.
Regarding the increased drag, that is another reason not to advise idle landings in jets, and most swept wing airplanes are jets. Jets Vref is closer to the reverse command region than props' Vref. This means that we have less speed stability and we can easily fall into that region if we raise the pitch too much without adding thrust positively. Haven't you ever been a few knots below Vref and have added a little bit of thrust to recover, but it didnīt suffice, and then added some more, with little result, and then more and more thrust until you realized that the thrust was well above the normal final approach thrust? That is the speed instability. If only you had added more thrust the first time you would have gone out of the limits of the unstable speed region, but little by little you remained there a long time.
Imagine an idle landing in that situation, a few knots below Vref (it can happen if actual weight is above computed weight, among other reasons).
As I said (well, as the 727 accident report said) it is no good idea to do an idle landing in a swept wing airplane.
Summing up, I think the reasons for discouraging idle landings in jets (with swept wings) are:
- higher sink rate
- steeper path requiring more manouverability for the flare
- reduced manoeuverability (here we disagree)
- speed instability (or little speed stability)
- possibly excessive time to spool up jet engines
Nice to review and discuss about this subject! I have to take a look at a few books I don't have right now to check what happens to AoA, g and speed when speed is 1,3 Vs.