I have never seen a set but I will order up a set and send some
pics when I get them, the ratio is a 3.21 and I am currently running
a 2.95
The best ratio I have run was a 3.16 when I was running the Ross
gearbox and I think the 3.21 will be better.
Ken
Ken,
The set-up is really good, but apart from higher (RPM = HP), explain to me
why you consider the 3.21 is better- or is it just the HP for take off and
high altitude cruise.
I can remember that Tracy was initially against going from 2.17 to 2.85
for
some reason - can't remember. I'm sure you will have to look at reducing
the
water pump and alternator RPM, but your probably doing that already
George( down under)
--------------------------------------------------------------
Tracy dammned soon changed his mind after he tried it :)
I had to work on him for three years or so to make the change :)
What is the Slauson part number on the stright cut plantaries?
I can'f find them in my 2001 catalog.
Paul Lamar ...No rotor no motor.
Paul,
It's in the 2003 catalogue, but I will look it up for you Buddy!
I will try and send some photo's as well !
Was Tracy's reasoning, just wear and tear at higher RPM, water pump and
alternator RPM - just can't remember?
I know that the nearer to the speed of sound without exceeding it gives the
best prop performance, but I'm unsure of how much it drops off at the lower
prop RPM, i.e. 7,500 / 3.21 = 2336 prop rpm and 6,000 / 3.21 = 1869 prop
rpm, but makes idle good even at 2,000 engine RPM / 2.31 = 865 prop rpm.
George ( down under)
I have no idea other than once you start making something it is
hard to change it.
Paul Lamar ...No rotor no motor.
With the 3.16 Ross redrive I was running I used a 70 inch six
blade Warp drive prop and when I switched to the 2.95 cog belt I had
to drop down to a 5 blade as the blades were running into disturbance
from each other do to the higher blade speed and when I switched to
that combination there was a big performance loss but it was a loss I
excepted as the Ross gearbox left me walking home too many times, now
I am just trying to gain that power back and I think the 3.21 will be
better than the 3.16
When ordering the prop from Warp drive they said that the best rpm
would be between 1900 and 2000 rpm for this prop on this plane with
this engine so that is why I ordered the 3.16 from Ross.
Since I went to the cog belt I have tried a 2.25 which did not work
at all, also tried a 2.8 which was barely acceptable and then a 2.95
which was the best compromise.
Ken
Ken,
I tried to find out some more info on the Allison's planetary ratios. Here
is one site I checked.
http://www.atlanticdda.com/transmissions/1000series_specification_sheet.cfm
It mentioned first gear is a 3.1:1 ratio. Is that ratio across the
planetary only?
Doug in Japan.
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