Long Range Question
The Long Range is 1% less than the Maxi range. So the following which is related to the maxi range can apply to the Long Range
PRIMO the Fuel Flow decreases because we are at at particular point of the CL/CD ratio graph (Cd/ square root of CL) and with the weight decreasing the thrust required reduces as the weight
SECUNDO(we are at high RPM, the SFC variation can be considered as neglectible) and the FF is going to vary as the weight (FF= SFCx W / (Cl/Cd ratio))
TERTIO There is an altitude optimum which is increasing with the reducing weight. However, over a certain altitude the compressibility effects increases the drag with the increase of TAS (we reach the critical Mach)and so the Long Range decreases. (This is reinforced for the Long Range as the Long Range speed is greater than the Maxi range).
As a consequence for a Long Range Flight, the Specific range increases at the beginning then decreases when the critical Mach is reached
Last edited by malaysian eaglet; 2nd September 2003 at 19:35.