From the propulsion support group:
The limitation placed upon the engine is a combination of the effects of cooling, mass airflow and fuel burn. These effects are different dependant upon whichever turbine we are talking about. A turbine requiring a large cooling factor, generally the older turbines will react badly in a hot environment due to the restrictive cooling and the restrictive throttle. A more modern engine with less cooling requirements will perform poorly with a greater emphasis placed on the restrictive throttle position caused by reduced the thermal expansion range.
SO! After a long and labourious thread it would seem that there is no winner or loser. The system reacts slightly differently dependant upon the aircraft, engine fit and age. Some aircraft, generally the older, respond poorly to cooling, hence not reaching their torque limits before the temperature. Others, with more efficient cooling systems reach the limit by running out of 'combustion space'.
It is a broad range of aircraft, situations and scenarios that we have and to flame someone for looking from a different view point as having no knowledge is a dangerous thing. There are very few 'black and white' situations in our profession.
Nick, thanks at the end I can see it from your point of view as well as my own and after flying the S-61 for too many years I have also learnt that there are other factors out there. The performance and limitations that I use have served me well in ops around the globe and I will continue to use them but I will also now include your theorys as well. It is interesting to see that a quick canvas of opinions at work resulted in 1. Blank looks, 2. Arguments for both ideas.
So..... Thanks all, I'll wait to see what comes up.
