The R-7755 had nine 4-cylinder inline water cooled blocks arranged around a
crankcase with a 4 throw crank. The liquid cooled radial was intended for
the pusher configurations of the B-35 and B-36. Engines intended for these
aircraft had an integral contra-rotating propeller gearbox in the nose case.
This is the configuration of the XR-7755 on display at the Air and Space
Museum.

The HK-1 was a tractor installation but liquid cooling would still have been
useful, particularly at high power settings used for water takeoff. Engines
for the HK-1 were to be single rotation.

These were VERY advanced engines with overhead cams, 4 valves/cyl, variable
valve timing and would eventually have had turbo-compounding.

Only the B-36 went on to production but with the 4360's it was so
underpowered that 4 jet engines were added. Had it used the R7755's no jets
would have been needed. Convair didn't design the B-36 to be underpowered,
they were forced to use the Pratt. Even so, I fondly remember the
earthshaking B-flat drone of a B-36.

The most interesting of these giants was the radar stealthy Northrop B-35
flying wing. This was the propeller version that was succeeded by the jet
B-49. With 40,000 HP, the B-35 would have been the fastest, longest range
prop bomber of all time even considering the turboprop TU95 Bear. It could
have carried more then 50,000 pounds of bombs to Europe and returned to
bases in North America. But, like Convair, Northrop was forced to use the
P&W 4360.

The cover story that the B35/B49 were cancelled because of "directional
instability" that made precision bombing impossible was nonsense. Just how
accurate do you have to be with a nuclear weapon? The real reason was that
the nuclear weapons of the time wouldn't fit in the Northrop's bomb bays.
Canceling the bomber for that reason would have tipped the Soviets to the
size of US weapons. Size and weight of nuclear bombs was top secret since
the first generation of ICBMs were then under development. The Northrop
flying wings were dead stable about all axes.

The history makes you appreciate the guts of the Smithsonian to put the
XR-7755 on display at all.

Bill Daniels

"John Sinclair" wrote in message
...
Bill,
If memory serves me right the 4360 had 4 rows of 9
cylinders for a total of 36 jugs. The aft rows were
spiraled to allow cooling to the rear rows, but even
so, the fourth row would run hotter. (KC-97F --circa
1952)
What was the configuration of the 7755?



At 13:48 19 October 2004, Bill
Lycoming engineers were confident that the R-7755 could
be developed to
produce 10,000 HP.