Originally Posted by CHELLIE
You are maybe thinking of older/cheaper ESC's with linear BECs?
If your ESC has a switching mode BEC built in then there really is no need for a separate uBEC for parkflyer size models. The Plush ESC for instance has a 3 Amp switching mode BEC*** which is by a wide margin more than enough the handle the four micro servos in a PZ P-51 (the peak amp draw per micro servo is about 0.25A).
Of course there is no harm in using a uBEC, but if you have a decent ESC with switch mode BEC it's not a necessity by any means.
that the hobbyking web site says the BEC is linear, but my recollection and at least one review on Hobbyking says it's switching, also the manual says it's switching: http://www.turnigy.co.uk/downloads/t...ser-manual.pdf
If in doubt it might be best to use another brand that definitely has a switching type, or use an external uBEC as per Chellie's advise.