rhovsquared,
.. one of the coolest threads ..
mmm .. I've always thought of FT and performance work as "technically and operationally interesting" .. I guess that equates to "cool" in young-folk-speak.
.. be applied under the FARs ..
No reason why not .. one just has to make sure that the basic rules applying to the particular takeoff (trapezoid, etc) are addressed. Not in any way a polar, regression, or differential expression .. just simple grass roots geometry/trigonometry .. normally about 14-15 year old high school level.
.. include tailwinds...
No reason not to include tailwinds provided that one is sensible .. considerations of local knowledge regarding wind profiles, etc. The normal 50/150 requirement provides a pad for wind components, regardless of whether we are talking head or tail.
OS prefers to leave tailwinds out and that is his reasonable decision .. I have no problem with tailwinds but would include suitable pilot training to make sure that the folk have a good handle on the problems and use tailwinds as an exception rather than a rule ...
So far as other simple methods are concerned, some have been addressed earlier in the thread .. including
(a) make sure that D1 lies within the available TODA
(b) make sure that G1 is not less than TODA/STODA
After that, it gets a bit more complicated ...
Terms (and apologies for not defining these before .. we get a bit slack at times, I'm afraid ...)
D1 = first segment distance
G1 = first segment gradient
D2 = second etc
G2 = second etc
H3 = third segment acceleration height. The significance of this is that it is a net height which is very much lower than the gross height used by the pilot. The net height is the basis for obstacle clearance and it is VERY easy to get caught out with this one using obstacle clear surfaces for an analysis ...
The reference to sledgehammer (in respect to (a) and (b), above) doesn't infer anything technical .. rather that the techniques are addressing the problem at hand in a manner which is rather conservative and unsophisticated ... but very quick and easy for line use. Apologies, just me being a bit Ocker, I guess, in my terminology.
... FAR 25 also has the 50% rule ..
The reference is to the takeoff run required. This is one of the cases one has to calculate as part of working out the max takeoff weight for the day.
TORR is the takeoff GROUND distance plus a proportion of the flare distance from liftoff to the 35 ft screen height. The old UK BCAR rules required the first third of the flare distance to be over the declared TORA while the US (and, I presume, the EASA) requirements are a bit more conservative and require the first half of the flare distance to be over the declared TORA.
The basic aim of the TORR is to make sure that the aircraft actually does get airborne prior to the end of the runway hard surface ... it could be a tad embarrassing to have the aircraft go into the soft dirt beyond the runway head and roll itself into a flaming, smoking ball ...
OS,
Thanks for your elucidation .. and we still have to catch up for that beer o'clock appointment ....