So do I have this right... just to try to make it more clear.
Vfe = Flap Extension Speed, the maximum speed at which I can Extend the flaps (and probably retract as well)
Vf = Maximum Flap Extended speed, the maximum speed I can fly with the flaps extended.
Vfe is probably determined by the force required to move the flaps, i.e. why you might like to slow down to extend manual flaps or reduce the load on the flap motor.
Vfe the speed at which if exceed the flaps might fail.
I was looking for an article on a test flight in a glider, found this instead...
"In Britain, unlike some other countries, it was legal to fly in cloud providing the sailplane was suitably certificated. Loss of control in blind flight was a well recognized danger, the usual outcome being an increasingly steep spiral dive with rapidly rising airspeed, very high g forces and serious structural collapse. It had been decided long before that a sailplane approved for cloud flying must have airbrakes which, when fully open, would restrict the airspeed to the maximum permitted in rough air. It would be very difficult to sell the HP-14C on the home market without a cloud-flying airworthiness certificate. The flaps certainly limited the speed once they were fully down, as Williamson proved in his own test flying, but, if the airspeed was already high and rising, the effort required from the pilot to get the flaps down to 90' was too great. If the sailplane was genuinely going out of control in cloud, the flap brakes would be useless"
The article I was looking for and didn't find I think was in the US and a Pilot tried testing the speed limiting flaps in a similar sailplane. on the 1st test both flaps failed simultaneously. They worked fine on the second attempt after being repaired and reinforced. Interesting a vertical dive actually required a forward pitch about 100 degrees.
EDIT- FOUND IT...
Here is an except from the article I was looking for and a link to the article.
"Experience has shown that about 100 pounds is the maximum that the average pilot can apply to the flap handle in this particular cockpit arrangement. Full flap extension requires about 100 pounds of force at 80 knots which gives a steady dive angle of 45 degrees at this speed. Flaps may be locked down for steeper dives and the terminal velocity in a vertical dive is 115 knots which results in flying at a fuselage angle 11 degrees beyond the vertical. In these tests, the standard HP-14 flaps failed in torsion about 6 inches outboard of the root driver rib as a speed of 102 knots. Fortunately both right and left flaps failed at the same moment and in the same manner so that recovery was possible without undue rolling. The failure resulted from the buckling of the unsupported skins in the 21inch root segment of the flaps. Intermediate ribs were added to provide a 7-inch spacing in this segment. Later dives to terminal velocity (115 knots) were made without incident."
http://www.soaridaho.com/Schreder/HP-14/T-6.html
Brian
CFIIG/ASEL
