---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Sun 11/04/18: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:52 AM - Re: HKS / Firestar STATIC THRUST test (John Hauck) 2. 08:16 AM - Re: HKS / Firestar STATIC THRUST test (Larry Cottrell) ________________________________ Message 1 _____________________________________ Time: 06:52:44 AM PST US From: "John Hauck" Subject: RE: Kolb-List: 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 _____________________________________ Time: 08:16:50 AM PST US From: Larry Cottrell Subject: Re: Kolb-List: 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 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 > > -- *The older I get, the less tolerant I am of those who are intolerant of others.* *If you forward this email, or any part of it, please remove my email address before sending.* ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kolb-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kolb-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kolb-list Browse Digests http://www.matronics.com/digest/kolb-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.