12
The Pilatus climbs at 4091 feet per minute
and right now, with our Catto 3 blade prop, we are climbing
at 5000 feet per minute with the blow off valve set to only
60 inches of mercury.. Up to 80 inches is available.

Craig Catto tells me with a 4 bladed version of our
prop we can get 30% more thrust.

Paul Lamar

 Hey Paul i was watching that video of the TTC run and had a few
questions I see the tach fluctuating a little but more importantly I was
wondering why when he pulls the throttle back and the rpms drop the oil
pressure rises. If I am reading it correctly which I may not it seems to
be in the low 60s in climb at high rpm and then as the rpm dropped it
instantly rose with rpm reduction close to 90. What's your thoughts on
that or was I looking at it wrong. Love the sound of it keep the videos
coming.
 Thanks, Jacob Sturges

 Me too. I am still trying to figure that  out.

 The 4 gallon  oil tank is in there at an 45 angle. I suspect
the oil pump
 is having trouble sucking oil. We are considering cutting it down
 and mounting it vertically  with the outlet closer to the
intake on the pump.

 This was done before I came on board.

 Paul Lamar

    Hey Paul,
    That could be the reason for loss of oil pressure, we just put
together a LSX turbo engine in a rear engine sandrail and put the oil
tank in the nose for wieght balance,  it has a 128" wheel base so the
hoses must be a 135" to 140" and we have not had any oil issues. The dry
sump tech did have us run a huge oil line because of the length, so that
might be worth looking into. If I remember from the images I don't see a
belt drive so the TTC is probably gear driven, I don't know if you can
change gears or slow the pump down somehow, maybe the guy who specd the
dry sump speed  is not used to spinning +8k rpms and has it spinning too
fast.  Keep me posted I'll be interested to see what you find out.

    Thanks, Jacob Sturges

    Do you spend any time on a 45 degree down slope?
    Our sump is below the engine and your sump is above the engine.
    I think we have AN-16 hose. The pump is direct drive and runs
    at 8000 RPM.

    Paul Lamar


 We defiantly see some really steep and weird angles at the dunes
in Dumont and Glamis, there extremely tall and we had to put a little
angle on this car as well. I would think in the TTC the oil tank is
level in the climb. The other thing is our belt set up is really close
to half so when we are doing close to 8000 rpm the pump is only doing
4000 rpm, so hopefully it's not cavitating, might be worth asking the
pump manufacturer.
Thanks, Jacob Sturges

It is vertical but the pump is above the oil level in the sump tank.
The outlet hose to the pump is about 2.5 foot long and it is
a dash 16. The larger the ID of hose the lower the suction
pressure and the oil column to lift is heavier due to the hose ID.
There is more oil to lift.

I think my logic is right but I could be wrong.

Paul Lamar


Hi Paul
When you are climbing at a constant velocity the weight of the oil is a product of oil mass and head so the pump sees a given negative pressure which produces a small amount of cavitationor reduction of performance.
When the pilot reduces the power on a steep climb, the aircraft goes into negative acceleration so the weight of the oil is reduced significantly and the pump inlet sees a significantly increased relative pressure at the suction port so reduced cavitation ( or zero cavitation ) so increased pump performance and higher pressure.
REgards
Bill Mc Donald

That's what I thought. When the pilot reduces to the power he also levels off.

Paul Lamar


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