PA-38 Tomahawk Spin Characteristics

[Pilot DAR]

The wing on the airplane is not the one that underwent certification, and engineers have complained that the increased flex in the modified wing is detrimental to the performance of this particular air foil.

If the wing is legally installed on the plane, it underwent certification flight testing, and demonstated compliance with the requirement to be able to be recovered from a spin.

If the wing flex has been changed, a massively complex engineering and test exercise must have been undertaken, which would involved lots of spin testing. For the wing to be affecting the performance of of an airfoil, the wing torsional stiffness must have changed, which I very much doubt.

Everything on and aircraft is designed to flex a little when under load. Usually it's just not enough to be able to see. There's nothing wrong with some flexing, as long as it is under condtions which are within the manufacturer's intended limitations. Ever seen the upper skins of a 100 series Cessna wing, in a 3 G turn?

[goldeneaglepilot]

I do remember that in the early 80's the PA38 in the UK was only cleared for intentional spinning during either initial airtest for issue of a CofA or star annual. I also remember seeing a letter from the CAA strongly suggesting that a parachute should be worn during the airtest (no mention of nappy or rubber pants though)

Yes - the tailplane does flex the fueslage during the spin. Yes, it also clunks and bangs, but it does recover predictably. It just takes time (and height)

The mechanics face is fun to see though, if he's flying on the airtest as an observer

[Pilot DAR]

CAA strongly suggesting that a parachute should be worn during the airtest

For flying those few (any?) Tomahawks with jettisonable doors? Or, did the author simply think that the whole fuselage would split open to allow you to exit in flight?

[Genghis the Engineer]

Originally Posted by Pilot DAR

For flying those few (any?) Tomahawks with jettisonable doors? Or, did the author simply think that the whole fuselage would split open to allow you to exit in flight?

You could extend that argument to spinning in many aircraft types. Given that even the most benign spinning aeroplane can hit that one in a million set of conditions and lock in (Bulldog, T67....), is it appropriate to ever deliberately spin anything without a get-out-of-gaol-card: a parachute and canopy/door jettison being the most obvious route out for most aeroplanes.

G

[18greens]

Has anyone tried the application of full power after full opposite rudder to help the airflow over the rudder correct the spin?

[goldeneaglepilot]

I suspect that the man at the CAA who sent the advisory note about the flight testing of PA38's at the time, who might have been or was related to the designer of the door catch mechanism. It was never the best in the PA38.

I never questioned the wisdom of the advisory note - after all the CAA always knows best....

Might be worth reading: http://www.aaib.gov.uk/cms_resources...1%20G-BGGH.pdf