McDonnel Douglas A4 Skyhawk

[chris keeping]

Has anybody got any ideas why the A4 Skyhawk rudder was made in skeletal format, ie the ribs supporting a central core, as oppose to being covered , as is normally the case?

[EnginEars]

I'd imagine the Skyhawks rudder was ribbed as an aerodynamic device (and stiffness aid) to get rid of flutter.

I'm sure I've seen similar things on other aircraft control surfaces. Jet Provost for example. Struggling to think of many others though.

Anyone else?

[ORAC]

According to Ed Heinemann, Combat Aircraft Designer, Heinemann, Edward H and Rausa, Rosario: (Annapolis, Maryland: Naval Institute Press, 1980), it was found to offer the solution to problems encountered with rudder buffet.

[Archimedes]

It originated as a temporary fix to the problem, too. Heinemann always meant to design something better, but never quite managed to get around to it...

[chris keeping]

Thanks for the answers gents. Just goes to show what a good forum this is!