Thomas Parkes wrote:
Paul:
In reply to your query, Yes I'm very much still here, but very, very
busy.
On the one hand I'm working 40 hrs per week teaching CFI academics.
On the
other I'm diagnosing problems with my Ross redrive, which at 78 hours
has
developed a fatal illness.
I mentioned last month that I'd detected metal particles in my oil.
Since
then I've traced the problem to a broken Sun-gear tooth, which tore
up the
Planetary pinion gears. Only one tooth was slightly damaged in the
Ring
gear, but there were several gouges inside the ring-gear bulkhead.
See
attached photos.
Notice that the Sun-gear tooth failure began at the oil lubrication
hole.
Notice also the apparent galling of the sun gear teeth. I don't know
if the
tooth failure caused some of this galling, or if it occurred previous
to the
tooth failure.
I had hoped to repair the redrive and replace the 4-pinion planetary
with a
six-pinion unit, but with the galling of sun-gear teeth I am
wondering if
the effort would be worthwhile. A couple local mechanical engineering
retirees tell me that the tooth failure appears to be a high-cycle
fatigue
failure, although it may have been damaged during the manufacturing or
assembly process.
My next step is to dissassemble the forward housing to inspect for
further
damage and see if the prop shaft and bearings are usable. More on
that
later.
Tom Parkes
Looks like you will need a whole new set of six pinion gears from
Slauson Transmission.
First hard data that the turbo three rotor is too much for the C6 four
pinion
version. Any sign of overheating in the gears Tom?
Paul Lamar
-Theodore James wrote:
Paul, this was sent to me from a customer of ours and I thought it
deserved a little discourse. Thanks again for the forum.
It is good to know that Tom Parkes did not have even more serious
consequences. After this experience a Powersport drive appears to be
very inexpensive when juxtaposed to the eventual cost of replacement
and the potential cost of failure in flight. These pictures are very
revealing. And no, the answer is not more planets. The answer is a
properly designed gearbox that properly considers harmonics.
In response to the issue concerning Everett Hatch's design later
re-engineered by Powersport: Powersport did in fact do complete
re-engineering, and has established accurate parameters concerning
harmonic forces, heat expansion etc. BTW the operation of a three rotor
configuration requires a properly designed harmonic dampener on
accessory end of the drive shaft. It will prove to be folly - if not
worse - to ignore such fundamental considerations when applying any
reduction system to the engine. Again, in retrospect, the Powersport
drive would appear to be a very economical and wise option.
As to Bill Jepson's assertion that he could build a FWF - FADEC
controlled ported 13B making 215hp+ for less than Powersport; Why not
do it then - and we would be glad to buy our future orders from
whomever the person who does the project and that person can take the
huge profit.
Respectfully,
Tedd James
Powersport Aviation
I thought Power sport was out of business. Last time I heard from Ray he
said it was a good hobby and not a business. Are you still trying to sell
PSRU's?
The torsional stuff is BS. We don't have any torsional problems. The tooth
with the hole in it was simply over loaded. We have tens of thousands of
accumulated hours behind Ford based planetarias over a period of twenty years
and that is far far more than Power Sport can claim with your over priced
over weight product.
As far as your 215 HP $30,000 Mazda 13B based rotary engine
is concerned an off the shelf brand spanking new 238 HP RX8 engine is only
$5,800 plus $3000 for one of Tracy's PSRU's.
Furthermore Power Sport has never tested their PSRU with a turbo three rotor.
With PR people like you Power Sport does not need any enemies.
The first thing a businessman learns if he wants to stay in
business is never bad mouth your competition. I told Ray this years
ago but apparently he did not get the message.
Paul Lamar
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