On Nov 25, 8:29*pm, wrote:
On Nov 25, 7:47 pm, wrote:

Lycoming has made several geared engines over the years and none has
been particularly successfull. I believe the Merlin *(or one of the
big "V" engines) was also geared.

* * * *Both the Merlin and Allison V-12s were geared. And most of the
big radials were geared. It was one of the few ways to get more
horsepower out of a given displacement.

R-1830 radial cutaway, with gears in the front of the case:http://aviatechno.free.fr/vilgenis/i...830_02_730.jpg

Merlin cutaway:http://www.thunderboats.org/history/...tory0324_1.jpg

Common geared Lycs: GO-435 and GO-480. Continental had the GO-300 and
GTSIO-520.

Daimler Benz DB601a:http://www.aviation-history.com/engines/db601a-1.jpg

* * * * Geared engines are nothing new at all.

* * * *Dan

One of the reasons that converting an auto engine by adding a PRSU is
complicated is that auto engine bearings are not designed for thrust
or side loads. The rear bearing of an auto engine in a car just sees
torque loads.

The PRSU has to be coupled to the crank in the same way as an auto
transmission which means that the small gear or pulley has to 'float'
on its own bearing and couple to the engine's flywheel through
something like a flex coupling.

Geared radial and a few in-line engines used a planetary gearsets.
This is easier since the "sun gear" sees no thrust or side loads. The
"ring gear" sees all those loads.