Could I ask for directions to any authoritative source which suggests that one needs 5 degrees bank for optimum climb ?
FAR 25 and AC25-7A (which is, by far, the more useful document) only talk of 5 degree bank in respect of Vmca determination .. where this is a maximum bank limitation to prevent unduly innovative flight testing by manufacturers.
On the presumption that most, and possibly all, certifications are based on 5 degree Vmca determinations, it is a good idea to be very bank sensitive with a failure under critical conditions at low speed.
Due to the sensitivity of "real" Vmca to bank angle and especially with a swept-wing jet, a failure (or better still a good birdstrike or rotor seizure model) during the takeoff rotation flare at low weight and minimum speed schedule presents the most critical handling case for the line pilot. In these circumstances, (unless the sim training sequence progresses to more critical situations sensibly in line with improving pilot manipulative capability) it is not at all uncommon to see pilots in the sim lose the aircraft in a Vmca departure at speeds well above the published Vmca due to poor bank angle control ... generally takes a few goes for the new pilot to accept that he/she must control bank, where necessary, very aggressively if the aircraft is not to be lost.
For this reason, many of my training failures are done during the latter stages of the rotation flare (which, I suggest, is considerably more difficult and demanding for the pilot than a steady V2 cut due to the dynamic nature of the total manoeuvre) .. working up (down/back?) to critical speed/CG failures ... makes for rather vocal (one gets to learn all the impolite expletives in any given language) and sweaty pilots .. especially when one then requires them to backtrack the opposite end localiser as well as handle the failure .. but the end result is that the garden variety V1 cut becomes a bit of a yawn .... and can be flown with an extremely high level of precision. I always find it very satisfying when the training exercise progression can be guessed just right so that the pilot, while under a reasonably uniform high workload and stress level, improves dramatically without having the spare capacity to realise the fact and then one can release the tension with a comment along the lines of "that's about it, guys ... it doesn't get any harder than that .. coffee break time".
Looking at climb data against bank angle, it is typical to find that the best performance is at a bank angle somewhere (relating to zero slip) between wings level and 5 degrees into the operating side .. typically we talk of around 2-3 degrees as being a good compromise. Often the performance is similar for wings level and 5 degrees (ie similar slip, but in opposite directions).
More interestingly, AC25-7A suggests that the certification intention is to fly OEI climbs wings level (unless that results in full rudder and a small bank is necessary to maintain heading).
I can't find any reference to 5 degree bank being relevant to, or necessary for, the OEI continued performance climb case (other than where Vmca might be near-limiting).
Perhaps some from the TP community who have specialised in OEI climb tests might care to comment ..... ? ... especially if they are able to provide de-identified test data ...
Last edited by john_tullamarine; 5th January 2003 at 02:45.