Thanks for your response.
As to the last question: what design requirement led to the final aft nacelle range put into the machine, allow me to use the original UH-60 Army RFP ( request for proposal ) requirements in a similar area:
The UTTAS ( and I am summarizing here, because I left the original documents with my successor upon retirement. This was such a " big deal" however. and generated such a number of meetings, before and during flight test, that I remember it well ) had to be able to land on some significant slopes as follows:
- Laterally at slopes of 15 degrees.
- Longitudinally, at slopes of 12 degrees.
The landings had to be done at design gross weight and at the extremes of the CG range.
For the longitudinal landings, that meant, for instance, that the nose down slope landings had to be done at the most forward CG ( and vice-versa for the nose up condition ).
Those requirements pretty much established the maximum control moment capability for lateral and longitudinal control, and thus the control ranges.
So, getting back to the V-22, I am guessing that there are/were slope landing and rearward flight requirements established before contract award, and these requirements may have resulted in the 97.5 degree nacelle number. Alternatively, there might be a sideslip to longitudinal aerodynamic coupling present in the vehicle and perhaps a consideration of this, and the desire to allow pretty much heads out of the cockpit flying when converted, led to the nacelle range selected.
There is one other question that I have pondered, after reading your comment regarding the 75 degree nacelle/40 KT limit during forward transition. The question is, with a FBW control system, why not put that control law into the software, thus eliminating that error possibility?
Appreciated the background on wing incidence selection. Sure there were some "spirited" pow-wows at Bell/Boeing before that subject was finalized.
Thanks,
John Dixson