Alex,
You're right, it seem a little unclear and in my honest opinion this question is a unfair and there are grounds to send it back to CAA for a re-word. A tanacious battle would be on their hands if the refused. VS1 is also defined as a stall speed in a specified take off configuration. This then means it is restricted to either 5° or 15° flap setting for specimen aircraft 737. Making it a little clearer that the "slowest possible speed for any given config" would be the better answer because it would include all possible range of flap.
Alex, there was also one question which begs to be clarified from yesterdays exams and I would very grateful if students who saw this question could correct the wordings.
"Flying at Vmd at a constant angle of attack, what is the effect on ROD, Descent angle and the L/D ratio if you maintain a constant forward speed at a lower mass"
a) increase increase increase
b) increase increase decrease
c) derease constant decrease
d) no idea.
This is tricky. The question hinges around this point. Is the lower weight aircraft at the old Vmd or the new Vmd (lower weights have lower Vmd).
The suggestion is that speed is constant and angle of attack is constant and therefore the aircraft is still at the old Vmd. If this were the case then angle of descent would increase (because you are no longer at best descent range speed or best angle of descent speed) With the same descent speed as before but now with a higher descent angle then ROD would increase and since you are not at the new Vmd, then the L/D ratio would decrease (Vmd being max L/D ratio)
Answer A.
However if the question is just poorly worded and the JAA mean the aircraft is at the lighter weight Vmd then the answer changes wildly. ROD would decrease, descent angle would remain the same and the L/D ratio is constant.
Please clarify my thinking and or make suggestions whether the wording is correct.
TA
Last edited by pugzi; 5th November 2003 at 17:53.