Paul Carey wrote:

 Hi Paul

 Thought you might like to see pics of my drag racing engine, after an
 overhaul and modifications.
 We put Tracey's apel seals in there - so this should be a good test for
 them!

 The sump plate is to be welded to a structural box sump - to stop the three
 rotor twisting on launch
 and high boost. And yes - that is a Piper Chieftain dual magneto. The engine
 has run before, and
 on alcohol, sounds like a Top Fuel dragster.

 I enjoy your posts guys.

 Regards

 Paul Carey LAME, MC
 Aero Management - aviation consultants.
 www.aeromanagement.com.au
 (08) 9371 5205  0418 959 892

Really interesting looking engine. Got a torque curve for us?

What is the evidence that the motor is twisting on launch Paul?
A lot of guys install a bunch of hollow dowel pins around the tension bolts
which would have the same effect. The two that are in every engine
between each housing should do the job. Come to think about it... perhaps
the end housings are cracking around the stock dowel pins on high power
engines as I recall.

The magneto drive looks expensive. I would think triggering a bunch
of MSD ignitions off the e-shaft or flywheel would be less costly,
weigh less and
might work much better than an aircraft mag. What is happening in the
states is most of the experimental aircraft guys are switching to solid
state ignition systems. My next door hangar neighbor Klause of LSE is
making most of them.


Paul Lamar

   I agree aircraft mags are antique. People cut 1 gallon per hour
fuel burn by going to that STC'ed electronic conversion and that
ain't nothing compared to an MSD unit.

   Ken

MSD does make what they call a Pro Mag. It bears no similarities with an
aircraft mag. My guess; it is probably a AC generator with electronic switching
through a voltage step up coil. They call this the "points box".
I am not exactly sure how it works. 

In an aircraft mag the peak current out of the AC generator
is always in phase with the cam shaft and timed around the point where
the spark needs to fire. That is when the points open
causing a rapid change in primary current thereby firing the spark 
plugs. The high voltage coil is in the mag with the low voltage coil 
doing the current generating. It is basically the same as a points and 
battery type ignition system with a primary coil providing the current 
instead of the battery. 

MSD has separated the two coils.  In the MSD Pro Mag the medium voltage 
output of the AC generator is switched on and off with transistors and fed 
to a coil in the "points box" that steps it up to the 40 thousand 
volts required by the spark plugs I think. I am guessing here. It does this 
for 26 crank shaft degrees. The top of the Pro Mag looks like a simple 
distributor cap with a center connection for the external coil and 
connectors for the high voltage spark plug wires.

There are two version. A 12 amp version for gasoline and a 44 amp 
version for nitro methane powered drag racers. The 44 amp version
has a entirely separate coil.

http://www.mdspromag.com

The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.