Thank you for your answers.
There is this quote from the article which says :
"It takes more fuel to indicate 300 kts at 10000 feet than at 5000. The air particles hit the aircraft with the same force, but in a given amount of time, more of them hit it."
That's the point that confuses me and which seems contrary to Capn Bloggs statement (I understand this is only a part of the problem, and that other variables may offset the above statement) :
At 250KIAS at Sea Level (TAS around 250), I use about 2100kg/per hour. N1 is way down, around 60%
At 250KIAS at FL300, I will still use around 2100kg/hr, but TAS is around 400. N1 is way up, around 85%.
Do you agree on the fact that IAS (then parasite drag) is determined by the force with wich the air particles strike the aircraft, and not the amount of air particles ? Instinctively, I would think that if more particles hit the Pitot tube, the pressure felt would increase (and IAS increase as a consequence).
You are right Keith, I want to make sure I understand the basics of power required before we talk about propulsive efficiency, SFC etc...
Thanks again