("Martin X. Moleski, SJ" wrote)
Are there any planes out there that have two engine, but can't be flown
on one?

Research: P-38 Lightning

With one of the P-38's dual fins and rudders always in the slipstream of a
live engine, a stall could be performed with little or no wing drop. It
was a pilot's dream under the trying conditions of a single-engine
approach andlanding."

http://findarticles.com/p/articles/mi_qa3897/is_200307/ai_n9283659/pg_5

http://www.vectorsite.net/avp38.html


The "Critical Engine" problem ...(x)2 ...was mainly an issue on takeoffs. My
bad. I've been set straight, so to speak.

http://www.fighter-planes.com/info/p38_lightning.htm
[That would not be until later, however, and the new P-38 had other defects.
The most dangerous problem was that both engines were "critical"
engines-losing one on takeoff, which happened often, created "critical
torque," rolling the plane towards the live engine's wingtip, rather than
the dead engine's. Normal reflex in pilots flying twin engine aircraft would
be to push the remaining engine to full throttle when they lost an engine on
takeoff, but in the P-38, the resulting critical torque would produce such
an uncontrollable level of asymmetric roll that the aircraft would flip over
and slam upside-down into the ground. Eventually, procedures were devised to
allow a pilot to deal with the situation by reducing power on the running
engine, feathering the prop on the dead engine, and then increasing power
gradually until the aircraft was in stable flight.]


Montblack