On Fri, 06 Apr 2007 14:32:17 GMT, wrote:

On Thu, 05 Apr 2007 21:50:24 -0700, TheSmokingGnu
wrote:

How exactly does a synchrophaser work?

On a piston-pounder it is changing the propeller blade angle/engine
RPM via the prop governor. Some use a coil on the slave engine to vary
the spring pressure on the flyweight governor, some use a step motor
and a jack screw to change the OAL of the prop control cable to the
slave governor.

Have worked on turbo-prop and turbojet systems that use the same step
motor and jackscrew assy. On the jets, it varies the length of the
"throttle" cable...

BTW, on the stuff I'm working on now, you can choose between synch'ing
either the fans or the engine cores. The RPM's are adjusted by the
synch box tweaking the slave engine computer electronically.

There are two RPM pickup coils for each source (fan or core). One goes
to the engine computer/synch box, the other drives the needles up by
the driver's seat.

In "normal" engine operation, all the power lever/cable changes is a
variable pot signal to the engine computer.

TC