Neil,
This is great news for people wanting to
install a rotary!
I don’t know what drives the
selection of a gear ratio, but a better ratio would be closer to 2.5 to
1. This would make the use of more standard props easier. With this
high a ratio, you will need to run the engine at high rpm, or the prop will
have to turn at a slow speed requiring a high pitch on the blades.
Is the ratio selectable at all?
Bill
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
Sent: Wednesday, September 16,
2015 11:28 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] New psru
Finally the first PSRU with a reduction of 3.12 to 1. Pictured is
the basic box which is heavily based on Tracy’s
PSRU but with the larger reduction and 2 oil lubricated thrust
bearings on the prop shaft instead of a single sealed roller bearing in Tracy’s. This
psru will mount directly in place of Tracy's
2.85 reduction PSRU with no modification.
Now
to put to test to see if the practice matches the theory. Already found
one fault. The “O” ring seal that seals the main body of the PSRU
to the base that attaches to the mounting plate is outside all the attachment
bolts, which means that the oil can wick down the bolts and make a lovely mess
of your pride and joy. Now looking for more faults as this is easily
fixed. Unlike Tracy's
, this PSRU is totally sealed with O rings to ease dismantling with no clean up
of whatever gasket sealer you have had to use.
Now
the terrible part and still undecided as I am yet to cost a damper on the
drive. Sadly it also is not cheap and may yet cost near $500 for a
”bit of rubber”. Then comes a mounting plate as made by Geoff
Doddridge which he sells for around $400 USD. There is no point in me
trying to compete with Geoff as he does a magnificent job at a cheap price.
Freight is always a horrible price so he makes the plate and there is no
freight from Aust to be added.
The
total cost in Aust dollars (including Geoff’s plate) will be around the
$5000 which equates to $3500 USD. Then freight of possibly $200.
Currently looking at further reduction in price if you source the gear set
locally saving on freight both ways to Aust and back. I will have to
alter the way it is constructed so that all the mods can be done by you the
builder. Still looking!
So
far the progress. Neil.