Pablo K, I see that you are new to PPRuNe ... welcome, sir.
However, I would like to note that many of the people who post, especially here in the Tech Forum, ARE Industry acknowledged technical experts. Most post under pseudonyms for various reasons, others post under their own names. We have quite a few people who are very experienced experimental and certification engineering test pilots (such as John Farley - a simple search on Google will give you an indication of John's background which, by anyone's standards, is more than impressive), others are from academia (including more than a few with PhDs, post doctoral qualifications, honorary doctorates and, to my knowledge, at least one fulltime university professor who holds an engineering chair at a well respected university. In your own fields of interest, we have a number of very experienced airline operations engineers, ground and flight training personnel ... the list goes on and on.
While I don't expect that you will, necessarily, agree with their opinions (one of the strengths of PPRuNe is a bit of cut and thrust discussion) I do ask that you consider the appropriateness of showing professional courtesy and respect to men and women who are, at the very least, your professional equal.
I presume that the nature of some of your posts is a consequence of your new arrival on site and that your style of writing will relax a little over the next few weeks. It is always easier to extract oneself from an unfortunate position if one's path into that position has left one with an escape route ....
Please be assured .. we seek and value your input .. but we like to keep the tone of things appropriately professional.
regards,
John
In respect of wind and Vmcg, the effect can be very significant, typically varying from around 0.5 kt/kt to something in excess of 1 kt/kt, depending on Type and engine configuration.
The critical case is a crosswind takeoff with V1 at or near Vmcg-limited and a failure of the upwind engine.
The big gotcha is that the onset of Vmcg-related control problems typically is fairly rapid (considering failure speed) and apparent over a small speed spread (sometimes as little as 5 kt can be the difference between a raised eyebrow and very sweaty palms). As a result, if the real world Vmcg is much elevated due to crosswind, then there is a VERY real possibility (under low V1 takeoff schedules) that the scheduled V1 may be somewhat less than the elevated value and could see the aircraft leave the side of the runway with predictable results - unless the pilot is quick enough to recognise the problem and abandon the takeoff - even if this means an inevitable overrun on a short, ASDR-limited takeoff.
Be aware that the usual certification is based on nil wind although the old BCAR requirements looked at the 7kt crosswind case. This is fine, unless you have the failure with a 30 kt plus crosswind .....
As to what you do in the short runway or low weight case in a strong crosswind ? .. there are various ways to mitigate the risk and these ought to be part of operator protocols and training.
Critical engine usually relates to the handling case but, depending on the rule set you are working with, it need not be just this simple.
It is useful to keep in mind that the OEM manuals are the result of a struggle between a desire to provide information and the need to keep an eye on potential litigation ... ergo .. such manuals are not always as useful or detailed as they might be. In particular, the OEM must produce a manual which is suitable for all pilots regardless of resources, experience, and skill levels. In addition, if one seeks the physics behind the observation, then the OEM manuals are not the place to seek such explanations.
Last edited by john_tullamarine; 20th April 2004 at 01:57.