Question:

 Handpropping a rotary engine ... Possible?  Easy/Difficult?
Robin Berglund


 Difficult due to the gear box. One rotation of the prop is
 2.88 revs on the engine. A lot depends on the EFI tuning
 and the position of the fuel injector relative to the rotor
 housing.

 Also it is a function of prop inertia. A low inertia
 wood prop would not help.

 Paul Lamar


While the effort (perceived torque) to turn the engine with the prop
will be relatively high, swinging the prop a relatively short distance
will cause a comparatively large (and fast) rotation of the engine -
aiding in starting.  The rotary's relatively low compression ratio and
small displacement may make it possible.  In a way, isn't propping a
geared engine much like propping an engine with a large number of
cylinders?

Has anyone tried it?  It should be approached with great care as
propping any engine is potentially very hazardous.


Matt-



It is easy to turn the engine by advancing the prop by hand.  However,
Tracy's controller has a minimum speed and number of compression cycles
before it will trigger the injectors and ignition.  While that is a very
nice safety feature it makes hand proping impossible.  You could do it with
a different type of ignition system.

I have left my master switch on a couple of times.. easy enough to jump
start with a car.  But it is still important to run it on the ground long
enough for the battery to recover before attempting flight.

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net


I imagine this is one of those 'stuck at some remote island landing strip with a dead battery' scenario .  Of course it's a cloudy day so your cowl top solar panel won't work. Oh yea, the spare battery you have two right?  has some juice in it but doesn't act like it can turn the engine over for very long.  Well, if you don't want to be duct taping seven or eight pen light batteries together across the main battery leads you better go for plan B.  Plan B is  borrowed from what Mazda is already doing, right now, with their piston engine cars. Their starter motor is only used to bring number one piston up to TDC position. Then they direct inject fuel and spark it. The engine starts in under 0.3 seconds. Fast enough? Hurry! looks like  a bear is coming.

Plan B.
Requirements:
1. Enough 12vdc juice to operate a  fuel injector and spark plug for a few seconds
2. Arm muscle to turn the prop and the knowhow to realize when rotor one has a face at TDC.
3. A modified ignition system.
4. Injectors mounted so that they can spray directly onto the rotor.
5. Without number 4 you would need a bottle cap, a string and a spark-plug wrench.  Note to self*  Always carry duct tape and a few basic tools to work on the aircraft.

Action:
Turn ignition OFF.
Initiate electronic inject cycle or manually introduce fuel into the spark plug hole.  You are priming the engine in a non standard way.
Turn the prop enough to get the next face of number 1 rotor into position and introduce fuel again.  Repeat for a third time verifying once more the rotor face is at TDC.
You should have a well wetted rotor that is evaporating fuel while you reinstall the spark plug.
Hurry! I can see whole trees crashing on the mountain side and it must be bigger than a bear. Besides we are on a tropical island.
Go back to the cockpit, turn master ON, and then ignition  ON and press the  'Activate L1' plug for a few milli-secs. Engine starts.
Fasten the cowl carefully avoiding the prop and get the heck out of there.  Hey there is movement on the other end of the strip.
Fact. A Tyrannosaurus will  play havoc on your tail feathers but they are not known to fly.

Doug in Japan