Whats the deal with counter-rotating props?

Private wrote:
: I would like to throw an interesting (if maybe false? I have no personal
: experience or a cite.) factoid into this discussion.

: I have read that the P38 Lightning was equipped with counter rotating props
: that rotated in the opposite (down going blades on outboard side of engines)
: from normal direction resulting in an aircraft with two critical engines and
: much increased yaw force when either engine failed. This was done despite
: control issues because it resulted in 15 knots extra top speed as compared
: with CR props using typical configuration (down going blade on inboard side
: of engines)

: Someone more knowledgeable may be able to explain why.

Interesting. Perhaps less downward propwash on outboard ends of wings? Or
maybe propwash vorticies "lifting" the fuselage rather than "swatting it down?"

Just WAGs on my part.

-Cory


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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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