OK, this is from my aircraft manuals.

"At high speed some control surfaces have a tendency to 'flutter'. This is a vibration that results from the changes in pressure distribution over the surface as its angle of attack is altered.

"If part of the structure starts to vibrate (and control surfaces are particularly susceptible to this) then these oscillations can quickly reach dangerous proportions. To avoid this tendency to flutter, the designer needs to alter the mass distribution of the surface.

"The aim of mass-balancing is not for the control to be balanced in the sense of remaining level, but to alter the mass-distribution of the control to avoid any flutter or vibration.

"The mass balance is placed forward of the hinge line to bring the Centre of Gravity of the control surface up to the hinge line or even slightly ahead of it.

Acknowledgement - The Aeroplane Technical, by T. Thom.

So that's how "modern" planes are protected from it. Even the little Cessna I fly has this (and I could be asked about it on my Private Pilot's test). It's really a resonance/harmonics calculation for each control surface, including the wings. If you fly old biplanes you can sometimes see this vibration in the bracing wires betwen the wings.

I'm guessing that the TV programme you saw was about the Lockheed Electra around 1960. You are probably asking how the flutter problem showed up so early in its life and how Lockheed never found it during design or testing. That's what the aviation professionals at the time asked, too ....

(Edited for typo)

[This message has been edited by WHBM (edited 01-30-2003).]