Today's Message Index:
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1. 06:52 AM - Re: HKS / Firestar STATIC THRUST test (John Hauck)
2. 08:16 AM - Re: HKS / Firestar STATIC THRUST test (Larry Cottrell)
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Subject: | HKS / Firestar STATIC THRUST test |
I do things a little different, but it has all worked out pretty well in the end.
New engine and/or prop, perform static runs to get the prop pitch in the ball park.
I don't concern myself with what the static thrust numbers are. Never did
a static thrust test on any of my Kolbs.
Go fly straight and level, wide open throttle. Keep adjusting prop pitch until
I can just bump the red line at WOT, straight and level flight.
That exercise gives me the best climb/cruise. I don't need to adjust for best
short field, climb performance. I will have it. That is the nature of Kolb flight
performance. If you over pitch you will have less climb and cruise. Under
pitch and you are spinning your wheels, wasting power.
Unless Bill B's FSII is not remotely configured like Larry C's FSII, it should
have very similar performance figures. A little longer main gear legs and bigger
tires aren't going to make much difference. On one flight to Alaska I traded
my 8X6 tires for 6X6 to get a little more cruise speed. Couldn't detect any
difference in performance. Same results going from a Maule 8" Tundra Tail
Wheel to a Maule 6" solid rubber tail wheel. No difference.
One thing that will add a lot of drag to a Kolb is loose fabric. There are a lot
of Kolbs out there that don't have "really" tight fabric. Fabric has almost
a rubbery feel. I shrink the fabric on my aircraft extra tight. Fabric feels
like a drum head. All three of my Kolbs have had respectable cruise speed
too.
john h
mkIII
Titus, Alabama
-----Original Message-----
From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of Bill Berle
Sent: Sunday, November 04, 2018 1:49 AM
Subject: Kolb-List: HKS / Firestar STATIC THRUST test
Today was first engine run (after my recent mods). My modifications since last
test flight were:
1) Move oil cooler from top surface of the wing down to 12 inches under the wing.
2) Move oil reservoir tank down underneath the wing.
3) Fabricate a "solid" cover for the center section so that no air could "leak"
or flow upwards form the bottom to the top of the wing (causing drag and bad
airflow into the prop)
4) Move the fuel tank forward so it is now under the center of gravity, so that
the aircraft CG is not near the aft end of the CG rrange.
On this test run, we were finally able to do a static thrust measurement.
At 5850 RPM on the ground, the giant spring scale registered 250 pounds of thrust.
The engine is nominally 58-60HP at its redline of 6200 RPM, which means I
was making 94% of max RPM. This was with a 3 blade wide chord propeller, 65 inch
diameter, with 11 degrees of pitch measured at the tip.
So the purpose of this Kolb List post is to solicit data/opinion/experience from
Kolbers who have measured the static thrust on their Rotax 503, 532, and 582
engines and similar. I have NO IDEA if 250 pounds of thrust is a little, a lot,
average, below average, or incredible for a Firestar 2.
Kolbers...how does 250 pounds of thrust compare to what static thrust YOU measured
with your 503/532/582 on a Kolb?
Does 250 pounds of thrust seem correct for a "60HP class" engine... somewhere between
the 503 and 582?
How many pounds of thrust do YOU think is appropriate or acceptable for Kolb being
set up for short takeoff performance?
The next step is to finalize the center section cover (I made four or five of them
trying to come up with what would work best). Finally went with thin aluminum
sheet metal and Velcro. Once this is all finalized and installed, I can resume
my test flying, and see if this made enough difference to raise the cruise
speed to 65MPH.
Once I get to 63-65 MPH I can reduce drag using the streamlilned strut fairings
(from Dennis Carley / U-Fly-it) and work on all of the little drag redusing things
that Jack Hart has documented on his Firefly. Hopefully I can get my Firestar
up to the 68-72 MPH cruise speed that Larry C is getting on his Firestar
/ HKS setup.
Larry and I both have the same large bush tires and Firestar 2 airframe. I have
a different gearbox and longer landing gear legs than Larry does.
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
Message 2
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Subject: | Re: HKS / Firestar STATIC THRUST test |
I can't add much of anything to what John said, since most of my knowledge
comes from John in the first place. One thing I can add is that the
increase in airspeed comes from cleaning up the drag- strut fairings, gear
legs etc.
Anxiously waiting to hear how the plane is going to fly.
Larry
On Sun, Nov 4, 2018 at 12:51 AM Bill Berle <victorbravo@sbcglobal.net>
wrote:
>
> Today was first engine run (after my recent mods). My modifications since
> last test flight were:
>
> 1) Move oil cooler from top surface of the wing down to 12 inches under
> the wing.
> 2) Move oil reservoir tank down underneath the wing.
> 3) Fabricate a "solid" cover for the center section so that no air could
> "leak" or flow upwards form the bottom to the top of the wing (causing drag
> and bad airflow into the prop)
> 4) Move the fuel tank forward so it is now under the center of gravity, so
> that the aircraft CG is not near the aft end of the CG rrange.
>
> On this test run, we were finally able to do a static thrust measurement.
>
> At 5850 RPM on the ground, the giant spring scale registered 250 pounds of
> thrust. The engine is nominally 58-60HP at its redline of 6200 RPM, which
> means I was making 94% of max RPM. This was with a 3 blade wide chord
> propeller, 65 inch diameter, with 11 degrees of pitch measured at the tip.
>
> So the purpose of this Kolb List post is to solicit
> data/opinion/experience from Kolbers who have measured the static thrust on
> their Rotax 503, 532, and 582 engines and similar. I have NO IDEA if 250
> pounds of thrust is a little, a lot, average, below average, or incredible
> for a Firestar 2.
>
> Kolbers...how does 250 pounds of thrust compare to what static thrust YOU
> measured with your 503/532/582 on a Kolb?
>
> Does 250 pounds of thrust seem correct for a "60HP class" engine...
> somewhere between the 503 and 582?
>
> How many pounds of thrust do YOU think is appropriate or acceptable for
> Kolb being set up for short takeoff performance?
>
> The next step is to finalize the center section cover (I made four or five
> of them trying to come up with what would work best). Finally went with
> thin aluminum sheet metal and Velcro. Once this is all finalized and
> installed, I can resume my test flying, and see if this made enough
> difference to raise the cruise speed to 65MPH.
>
> Once I get to 63-65 MPH I can reduce drag using the streamlilned strut
> fairings (from Dennis Carley / U-Fly-it) and work on all of the little drag
> redusing things that Jack Hart has documented on his Firefly. Hopefully I
> can get my Firestar up to the 68-72 MPH cruise speed that Larry C is
> getting on his Firestar / HKS setup.
>
> Larry and I both have the same large bush tires and Firestar 2 airframe. I
> have a different gearbox and longer landing gear legs than Larry does.
>
> Bill Berle
> www.ezflaphandle.com - safety & performance upgrade for light aircraft
> www.grantstar.net - winning proposals for non-profit and
> for-profit entities
>
>
--
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