Why were the engines on the Junkers Ju 52 mounted on an angle?

The wing mounted engines of the Junkers Ju 52, a WWII era tri-motor, were angled slightly outward. Why? Wouldn’t this just waste thrust and make it more difficult to fly with an engine failure?

Fact: The Ju52 was designed as a single engined aircraft, and the wing engines added when the single engine design proved underpowered.

Speculation: The wing engine retrofit probably had to fit to existing structural elements in the wing (particularly the wing leading edge), thus resulting in the toe-out configuration. The engine is perpendicular to the leading edge.


From here: “The motors on the wings of the Ju52 are not perpendicular to the wing leading edge, but their thrustlines through the wings are perpendicular to the center of lift of each wing.
Apparently this is a deliberate design factor, the decision having been driven by the need to extract as much thrust as possible from the comparatively low-powered engines then available.”

It might have made the plane *easier *to control with a wing engine out, which would have been a frequent occurrence. The thrust line of the remaining wing engine would be closer to running through the airplane’s center of gravity, reducing the net yaw moment that the rudder had to overcome.

The loss of thrust wouldn’t be all that much, the cosine being close to 1 for fairly large angles. The prop blades’ angle of attack would be constantly varying, but could still have stall margin at any position.

My experience is with twin engined model aircraft, but angling the thrustlines outward is generally said to improve handling with one engine out.