RAH'er has forced landing

On Tue, 21 Dec 2004 20:30:12 GMT, Dave S
wrote:

It sure matters to me. The mazda rotary is about the only auto
conversion that I have even given any serious thought to. I have one
assembled on a stand at the hangar waiting to be put on the airframe.

Dave, you missunderstand me. What I meant was, whether it was the
engine, psru, fuel pump, carburator, or ignition system that failed,
the end result is the same thing: a dead stick landing.

It doesn't matter to the pilot that the engine is running just fine if
the prop isn't connected to the engine anymore.

The point is to use something that will last. Preferably something
already tested. Or at least that's my attitude. I don't want to be
somebody's test pilot, I just want to fly.

Corky Scott

On Tue, 21 Dec 2004, Ron Wanttaja wrote:

ACFT MADE AN EMERGENCY LANDING NEAR A ROAD 15 MILES SOUTH OF LEESBURG, FL


Hello guys, It was actually on a nice two lane road, no wires over it,
wide berms, no driveways or signs, and no traffic, at least until short
final.

I was climbing through 5500 ft when the note of the engine changed, I
checked the guages, all green, leaned the mixture, and reduced throttle.
Then heard a loud growl and then engine disengage from the prop.

I pressed "nearest" on my gps, and it listed Leesburg first, (I had just
left my friend there). I thought it said 30 miles distance, but that must
have been the heading, since Zepherhills would have been listed first.

Anyway, I had lots of time to select my landing spot, and picked a good
one. Which was near a divided highway. 11.5 miles from Leesburg.

Go ahead with your "I told you so's", just remember that there was not a
good alternative six years ago, and my junkyard gearbox has been good to
me.


George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage http://bfn.org/~ca266

On Wed, 22 Dec 2004 12:31:10 -0500, "George A. Graham"
wrote:

Go ahead with your "I told you so's", just remember that there was not a
good alternative six years ago, and my junkyard gearbox has been good to
me.

What's important here George is that you made it down safely and
without damaging your airplane. Not everyone manages to do this, some
die in the attempt. I'm really impressed.

The secondary part is I'd sure like to know what failed in the
transmission. It's helpful information so that future experimenters
can know about it.

It would also be helpful to know what you did, if anything to modify
the transmission to become a psru.

Thanks George, you really got a nice present for Christmas.

Corky Scott

PS, You're famous ;-)

Not to be a putz, but if you had talked with the people in the old
days who started putting "car" engines in boats, they would have told
you that automotive manual transmissions were tried and generally found
wanting. Marine transmissions have spring or elastic couplings, similar
to those on auto clutches but bigger, and the gears are oversize.

A torsion damper of some type-either a spring or elastic coupling, a
quillshaft, or a belt or chain with a little stretch-is an absolute
necessity. There's a simple way of measuring the torsion flexion which
can be quickly used to troubleshoot the problems: on either side of the
coupling, a "tone wheel" or regularly spaced magnetic or optical 'mark'
is placed and a pickup-a LED/sensor or a simple solenoid coil (think
electric guitar or Hammond organ)is placed. The phase relationship
between the two signals is monitored and as the engine/load are cycled,
where the two signals "wobbles" is where the flexion is happening.
It's a simple test to rig up. OMC and Mercury have been doing this for
years. I know because I worked in a music store in Wisconsin and they
would buy a certain type of internally amplified guitar pickup for this
purpose.

On Wed, 22 Dec 2004 12:31:10 -0500, "George A. Graham"
wrote:



Go ahead with your "I told you so's", just remember that there was not a
good alternative six years ago, and my junkyard gearbox has been good to
me.

you are one of aviations pioneers george.
not all pioneering efforts lead to anything in the long term.
honing anything useful takes time and often many dead end attempts.
we applaud your efforts.
what you have shown is that the approach is not too far off the mark.

6 years isnt too informative though.
how many hours were accumulated in those years?
how much work had the gearbox done before finding a home in your
aircraft?
Stealth Pilot
Australia.

On Fri, 24 Dec 2004, Stealth Pilot wrote:

6 years isnt too informative though.
how many hours were accumulated in those years?
how much work had the gearbox done before finding a home in your
aircraft?

The gearbox was used, over 80,000 miles when I got it, I installed new
bearings. It flew 415 hours in the six years. I suspect that the bearings
may have worn enough to disturb the gear lobe fit (but I don't know).
In hindsite, I wish that I had replaced the bearings at annual.

To share my understanding on other issues raised on RAH:

The Mazda Wankle has very low amplitude (strength) power pulses, since the
power stroke is over 130 degrees of the output shaft.

The frequency of power pulses is the same as a four cylinder four stroke
as there are two per revolution. However, if it starts on one rotor,
then every other pulse is removed, which lowers the frequency by one half.
That is not likely to happen on any other engine.

If you know the moment of inertia of each component, and the rate of
spring of the revolving mass, then you can compute the frequency during
which torsional resonance is likely. In my setup, that is 200 to 300 rpm
with both rotors running (double that on one rotor). The forces generated
by resonnance, approach infinity, so no "stronger" gears help much.

I did use an elastomeric dampener (clutch hub), and a quill shaft on
the tranny input (came with it).

Thanks for all of your kind words, I'm off to retrieve my airplane today.

George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage http://bfn.org/~ca266