Thanks for the explanation of reasoning behind the forward-sloped windshield. I've always wondered about that.
I have been puzzled that Lockheed (and AE) didn't use variable pitch propellers. I think I remember that AE's Electra was retrofitted with variable pitch propellers, but she later had them removed.
Earhart's 10E was delivered with constant-speed props. The blades were replaced after the wreck in Hawaii but the serial numbers of the hubs did not change.
Lockheed specs dated May 1, 1936 show the Model 10A (P&W 450 hp engines) and Model 10B (Wright 450 hp engines) equipped with "Hamilton-Standard Two-Way Controllable Pitch Metal Propellers"
The same specs show the Model 10E (P&W 550 hp engines) with "Hamilton-Standard Two-Way Constant Speed Metal Propellers."
The controllable-pitch (same as variable-pitch) prop had been around since 1929. Hamilton Standard introduced the constant-speed prop in late 1935. The full-feathering "hydromatic" prop didn't come along until 1938. (
http://notplanejane.com/hamiltonstd_info.htm).
On a multi-engine plane, the inability to feather the prop (turn the blades knife-edge to the wind) in the event of an engine failure is serious drawback. A "windmilling" prop on a dead engine creates tremendous drag.
In a variable-pitch prop, the pitch of the blades can be manually adjusted from fine-pitch for takeoff to coarse-pitch for cruise. The pilot has to make frequent adjustments to the propeller control to keep the prop pitch appropriate to the throttle setting (manifold pressure). In a constant-speed prop the pilot sets the propeller control to the desired RPM and the prop automatically changes pitch with throttle changes.
I've flown one airplane equipped with the old variable-pitch prop - a 1950s-vintage Ryan Navion owned by an Army flying club. Pain in the butt. The constant-speed prop was a big improvement.
I don't know of any multi-engine airplane now flying that does not have full-feathering props, including all of the Electras that have been restored to airworthy condition.