TODAYS Performance exam

[Keith.Williams.]

I think that you have picked the correct answers Spitty but for different reasons. I am also more concerned about the first question than I am about the second.

QUOTE
- what happens to the speeds Vx and Vy with increasing altitude for a given TAS?

a- both increase
b- both decrease
c-Vy remains constant, Vx either increases or decreases
d- ????????

My problem with this question is that the speed you have chosen to climb at (whether constant CAS, EAS or TAS) has nothing whatever to do with the variations in the values of VX and VY.

As discussed in previous strings on this subject, option (a) is true if we are talking about the TAS value of Vx and Vy. But option (b) is true if we are talking about the CAS values. I suspect that they are looking for the TAS values (option a), but there is nothing in the question to makes this explicitly true.

You could be climbing at constant TAS watching a Vxometer (indicating the value of Vx) and Vyometer (indicating the value of Vy) (yes I know such meters don't really exist). If these meters were indicating in terms of TAS, both readings would increase as you climbed, with Vx increasing faster than Vy. If you repeated the process having switched your vxometer and vyometer to CAS you would see the readings go down, with Vy decreasing faster than Vx. The question of what type of speed you were holding would not affect the readings on these meters

The most difficult question here is why do the examiners not ask something like " How do the TAS values of Vx and Vy vary with increasing altitude?" They could make a set of three questions covering CAS, EAS and TAS and we (the FTOs) would be happy that we were able to teach the subjects properly and expect the students to get the marks in the exams. Having expended a good deal of effort in ensuring that my students have a thorough understanding of this subject, I find it very annoying to see the hair brained questions they are then asked in the JAR exams.


QUOTE
- At what speed is the most induced drag produced for straight and level flight ata given alt and mass

a- Vmo
b- Vs1
c- speed for slowest flight at that altitude
d- ?????

If we take option (c) to include the possibility that we are using landing flap, we can go down to Vso without stalling. I suspect that this is what the examiner is after.