ATPL Perf Exam - piston a/c max speed

[Tee]

Struggling to work out the correct answer to this one, can anyone help? The wording is from memory but not too far off.

Maximum speed for a piston angine aircraft is found at?

a. practical ceiling
b. service ceiling
c. as low an altitude as possible
d. optimum cruise altitude

Thank!

[Young Paul]

I suspect there might be tighter wording involved - what sort of speed, for example? I know it's not a theory of flight paper, but still ......

[Mark 1]

This will normally be the highest altitude at which the max continuous power can be obtained.

Above that height the loss of power available will not be compensated by the improved density correction.

Below that height the reduced density correction will give a lower TAS.

[Keith.Williams.]

Tee,

The effects described by Mark1 are illustrated in the CAP 697 Figure 3.5.