---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Mon 08/27/18: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:53 PM - Lift strut fairings (George Helton) 2. 02:56 PM - First short XC Flight and Slow Cruise Speed (Bill Berle) 3. 03:37 PM - Re: First short XC Flight and Slow Cruise Speed (Larry Cottrell) 4. 06:34 PM - Re: Stabilizer Angle (Richard Girard) 5. 06:44 PM - Re: Stabilizer Angle (Richard Girard) 6. 07:18 PM - Re: First short XC Flight and Slow Cruise Speed (Richard Pike) ________________________________ Message 1 _____________________________________ Time: 02:53:38 PM PST US From: George Helton Subject: Kolb-List: Lift strut fairings I changed the subject line I received the 3:1 strut fairings on Friday afternoon from U-Fly-It . They s eem to be of very good quality. It took most of Saturday to align and instal l then over my 1 1/4=9D standard Kolb lift struts. Attached with 4 pop rivets. I closed the ends in with some dense form and sealed them some whit e Flex-Shot. The they look great. I haven=99t been able to get any performance figures yet because of ra iny weather. I=99m not expecting much change. I=99d be trilled t o see 5 mph at cruise. I took some cruise rpm and airspeed readings last wee k in calm air to get a rough baseline. George H. Firestar, FS100, 2702 Hirth 14GDH Mesick, Michigan gdhelton@gmail.com Sent from my iPhone > On Aug 26, 2018, at 10:48 PM, west1m wrote: > > > We are vacationing on the NC outer Banks this week. We went to the Wright B rothers Memorial today. While we were there several planes took off from the strip on the property. I was just wondering is anyone has flown their Kolb i n there. It looks like it would be a memorable experience. > > -------- > West1m > Hastings, MN > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=482709#482709 > > > > > Attachments: > > http://forums.matronics.com//files/wright_393.jpg > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= ========================== ========= > > > ________________________________ Message 2 _____________________________________ Time: 02:56:06 PM PST US From: Bill Berle Subject: Kolb-List: First short XC Flight and Slow Cruise Speed The other day I made the first flight out of the traffic pattern. I wrote two long and detailed posts on the homebuilt airplanes internet forum, and I am copying them here ont he Kolb List for anyone who is still interested in the subject of my test flight program on the HKS Firestar. These posts will be far too long and detailed for some of the folks on the Kolb List. But for those interested, here are the results from the first flight away from the airport, and the second post is trying to identify the causes of the poor aircraft performance. I am not including the responses from other participants on that forum, but the entire 11 page discussion thread from start to finish can be seen here by anyone with that much time on their hands: http://www.homebuiltairplanes.com/forums/showthread.php?t=30314 I'm the person posting under the screen name Victor Bravo, some of the guys refer to me as VB (Victor Bravo or VB was my old racing competition numbers in sailplanes 35 years ago) At this stage I am not nearly as concerned with the nose up and nose down trim, or the stabilizer angle. All that is manageable and can be fixed easily enough.This flight showed that I am just not getting the performance out of this aircraft that the average 503 powered Firestar should get.Fixing that problem is now a much bigger deal to me than the trim because it affects the overall usability and desirability of owning and flying it. Again, this may be far too much detail nd discussion for some people, please accept my apology for that if appropriate. Post #1 - Saturday evening Well, today was a two-flight day. Early this morning I did a brief local pattern flight in "Special VFR" visibility conditions to see if the large windshield I had installed (re-installed the one that had come with this aircraft) would make any difference in the aircraft's paint-blistering cruise speed or nose-down trim. I flew three or four times around the pattern, and did not see any significant difference. A little comfort, yes, but significant improvement in speed or nose-down force... no. And a cabin entry/egress process that is very embarrassing. The large windshield makes the front of the aircraft look like a badminton birdie, with about the same amount of drag. But I had not gotten to anything resembling a cruise altitude, nor had I let the airplane settle into any sort of cruise configuration. Today was also the first flight with working two-way communication, using a borrowed helmet/headset/handheld radio setup. So later in the day after the control tower opened up, I took advantage of being able to have two-way radio, and set out on the first "major cross country" flight. My goal was to get from Whiteman Airport to Agua Dulce Airport, a distance of 23 miles (including the 90 degree dog-leg detour through the Newhall Pass). I figured this was a modest goal, but it was first trip out of the local airport pattern. The fuel system I had put in it was not working very well. I have two 5 gallon tanks, but there is no inter-connect between the tanks. They both have pickup lines coming into the tank from the top, because i did not want to put fittings into the bottom of the tanks where I couldn't see or deal with a fuel leak. Both tank pickup lines run to a gascolator, which is on the suction side of the electric and pulse fuele pumps. So I had assumed that the pump would "suck" fuel from both tanks more or less equally. I was wrong, the fuel in the font tank is used much faster than the rear tank. So I filled the front tank up to the 5 gallon level, and as Lonesome George Thorogood and John Lee Hooker say... "and down the road I went". The cruise speed is still 45 - 47 MPH IAS at 5300-5400 RPM, which is about 91% of the 5800 max. continuous RPM. So this was "high cruise" and not anywhere near "economy cruise". Worse yet, 5400 is still 85% of the "5 minute takeoff rating" of 6200 RPM. Which means that I'm not even able to take advantage of the HKS' low cruise fuel consumption, on top of all the other issues. We also had our SoCal light southwest breeze today, about 10 knots. By the time I got to the Sand Canyon Country Club golf course, I had traveled 15 miles, and realized that there was not going to be any significant increase in cruise speed. I also realized that I would have possibly a 10 knot headwind on the way back home. So I turned around at that point, and started heading back. By the time I got through Newhall Pass again (the initial reporting point for traffic going into Whitmen and Van Nuys), I also realized that my trans-sonic speeds were going to become an annoyance for the ATC people and everyone else coming through there on a regular basis. My friend in his Vari-EZ called in at Newhall Pass behind me and I volunteered to displace to the right of the final approach path to allow him to pass. By the time I landed at Whiteman it had been perhaps a 40-45 minute flight to go 30 miles It looked like I had used over 2 or 2 and 1/3 gallons of fuel from the front tank. To say I was disappointed taxi-ing back in would be quite an understatement. The engine ran well and the aircraft was reasonably stable and easy to fly. No major complaints there. I was also able to verify that I had reasonable pitch stability, in that it took a little forward pressure to go faster than 45 IAS, and to slow down/flare/land at 30 MPH it took back pressure. No major Grim Reaper lurking around the pitch axis even with my jacked-up stabilizer. Compared to the weight and balance results, and knowing there were a couple more gallons of gas on this flight, I am fairly certain that I was at gross weight, plus or minus five or ten pounds. Full throttle in level flight put me slightly above max continuous RPM but a hundred or two less than max permitted takeoff RPM. So I do not believe I am grossly "under-pitched" on the prop. The aircraft also does NOT "climb like a homesick anglel". It takes off in a couple hundred feet or so, and it climbs well enough to not be "a slug", but this is no Super Cub by any means. If I had this much power but my takeoff weight was 525 pounds (instead of 725) perhaps it would behave like a Super Cub. I am reasonably convinced that there are 5 or 8 miles an hour to be gained with streamline wing and landing gear struts. But those streamline struts will not get me up to 65 or 70 miles an hour which is about what Kolb aircraft using tis engine really ought to do. 70 miles an hour would allow me to blend in with "normal airplane" traffic and not becomee a PITA to the traffic controllers. 70 miles an hour would also allow me to use this aircraft for the mission I wanted it for. 45 or 50 miles an hour will not. So now I am at the point of grasping at straws to find out what is slowing this one down so much. It is not the lack of a windshield. Other Kolb Firestars have bush tires and still go 65 MPH. I have a strange oil cooler that works too well, and there's a chance that the air flowingo ut of the cooler is causing some huge drag-producing disturbance on the wing root area. There is a chance that my exposed engine and oil tank in the wing center section are causing huge drag somewhere. There is a chance that my unique exhaust and muffler are destroying the airflow into the propeller disc so much that I have lost a third mf the engine's potential thrust. But there is also a chance that I have just plain screwed up something so much in my custom engine installation that I am never going to be able to use this Kolb for the mission that I had intended. The Kolb is the only airplane that folds up small enough to fit in my hangar, so if the Kolb will not work then I am basically defeated in pursuing the kind of STOL flying that I wanted. Post #2 - Sunday evening Sorry to sound like a broken record, but thank you again to all the people taking time and brain cells to fool with this puzzle. To answer some random questions in no particular order: The airplane is at gross weight because I have several components that are heavier than a normal Kolb Firestar. My HKS engine is about 30 pounds heavier than the 503. I put HD oversize gear legs on which probably are 15-20 pounds more than stock. My tires are a LOT heavier than the silly little tires that they come with. I have a 4 foot stainless 2 into 1 exhaust, and then a custom 4 foot long muffler that weighs more than the stock litle "tin can". So when you stop and think about it fairly, it makes sense that this one is nearly 100 pounds over the brochure weight. I have a valid and reasonable mission-driven justification for each and every one of the changes I made, but the digital scale says what it sees without asking why I did anything. It is theoretically possible that the VG's are screwing around with something somewhere. However, it is known and demonstrated on many other Kolb aircraft that the VG's do not have adverse effects, and they are shown to reduce stall speed. I installed them at the chordwise location, spacing, and angle that was recommended by the VG manufacturer. Numerous similar and non-similar aircraft use VG's at the same location. More importantly, in general the VG's are reasonably known to improve or maintain attached turbulent flow over the wing surface. I am not aware of any "normal" VG installation that created a 33-40% increase in aircraft drag. Anything is possible of course, but I would be surprised if this were the problem. If all else fails I will remove them, but there are other things I'd look at first. The fuel probelm is that I do not have interconnected fuel tanks. They both feed the same gascolator, but there is no cross-feed or interconnect at the bottom of the tanks. I also cannot install a one-piece tank at that location, they can only be inserted into the airframe one at a time. So considering that I also have a CG that is indeed further aft than most of these aircraft (whether it's within the approved range or not), if I do any work on the fuel system I can get two birds with one stone by moving the fuel forward 18 inches and going to a one-piece tank... solving both the CG and fuel feed issues at the same time. Some information/observations that I had not discussed here previously. One or more of these may be causing the extraordinary drag and/or loss of thrust that is slowing me down: 1) I thought I had designed a really clever and low drag oil cooler mounting system. I may not have been as clever as I had hoped. The top surface of the cooler is flush with the top surface of the starboard wing root, just behind the maximum thickness of the wing section. I have an aluminum plenum box under it, which takes high pressure ram air from the bottom of the wing, then up through the cooler, and then exits the air into the low pressure field above the wing. It works too good, the first flights I had low oil temp. Even after closing off half of the scoop area, I still only got to 180 degrees F on the last flight. If this slug of pressurized air is shooting up through the cooler at a good clip, shooting into the relative wind at a 60 or 70 degree engle, it could possibly be making a "virtual spoiler" jet of air flowing upward from the wing surface and making a boatload of drag. No other Kolb that I know of has had the oil cooler mounted in this manner. Most of them just put it somewhere with it "facing" into the relative wind. 2) After the last flight I saw oil droplets and oil moisture on parts of the upper wing surface that should not have gotten wet. My oil tank is partially exposed above the upper wing surface, but it is about 55-60% of chors on the port side of the center section. The oil droplets (which presumably came from the overboard vent tube on top of the oil tank) were between 6 and 18 inches OUTBOARD and FORWARD from this oil vent tube. There is no source of oil anywhere forward (chordwise) of this oil wetting on that side of the center section. There is also no source of oil even with or outboard (spanwise) of the oil wetting area on the wing upper surface. So regardless of the actual source of the oil droplets, any oil that is deposited at the areas I am seeing had to be carried there by airflowthat was not moving lengthwise from from leading edge to trailing edge. The air had to be doing something really counterintuitive, going against the general flow direction and outboard at the same time. 3) In an attempt to force the main wing stall to begin at the root end and progress outboard, I left one rib bay near the inboard section of the wings without VG's. The location of the oil stains/droplets is in this "VG-less" rib bay on the port wing. So there is a possibility that there is some bound or stationary vortex. coming off of the VG-less part of the wing, and this vortex or circulation pattern is carrying oil droplets from the overboard vent forward and outboard, which would likely create a boat-load of drag somehow. interestingly, the center section fairing that covers the gap between the wings (20 inches wide) does have VG's on it because I wanted to have attached flow to make sure plenty of high energy airflow got into the Cub-style "eyebrow" cylinder cooling shrouds. So there is the possibility that the boundary between VG covered wing and naked wing is creating some spanwise vortex in addition to whatever other crappy flow thee is in that location. Spanwise vortex rotation (vertical axis of vortex rotation) would at least explain how oil is being thrown outboard from the original source. 4) Most Kolbs do not have any "cowling" or fairing in front of the engine on the top surface of the wing. Mine does not have a shaped cowling either. But the HKS is an opposed engine layout, and mine has some draggy items in the middle, where the 2 stroke engines are usually an inline layout. Between the engine cylinders, facing forward, I have a large 4x6 inch bracket that mounts the engine control cables and "splitters", some -10 size oil lines and several fittings, a few inches of oil tank above the wing, a bunch of wiring, two intake manifolds, etc. So it is possible that the engine and all of this junk is behaving like a 24 inch wide "spolier" taking up the entire center section of the upper rear wing surface, creating whatever parasite drag it creates and ALSO spoiling the in-flow to the propeller. 5) I have more drag-producing and flow-blocking components behind the steel "pylon" or "cage" than other Kolbs. There are a bunch of 1/2 through 3/4 inch steel tubes there on every Kolb, but then on top of that I have two 1.25 inch exhaust pipes right next to each other running vertically down the back side of the pylon. These exhaust pipes are 4 inches in front of the propeller arc, and would serve to disturb the in-flow to the prop more than even the standard "dirty" Kolb airframe. ________________________________ Message 3 _____________________________________ Time: 03:37:05 PM PST US From: Larry Cottrell Subject: Re: Kolb-List: First short XC Flight and Slow Cruise Speed It would appear as though you may have painted yourself into a corner. When I got my first one it would only fly at about 50 mph. The fabric had not had the full coats that is recommended by poly fiber and the texture of the fabric was rough. Not knowing any better I painted it with auto paint, which necessitated that I recover it some 10 years later, but it gave me about 10 miles more speed. I made a xcountry trip to NMex and used the cloth wrap around fabric that comes from the Kolb full enclosure, and it cut my speed by about 5 MPH. The plane does better with the "shuttle cock" configuration. Streamlined struts and legs gave me about 5-6 MPH increase. I have a couple of suggestions for you- secure a hose to the relief tube on the oil container and route it out the bottom of the fabric in the fuel compartment. It won't solve your air problem, but it will put the oil where it isn't a problem. As for the fuel tanks, I ran the "pickup tubes" to a selector switch at the left side of the seat, set the EIS to alarm at one gallon of fuel left, put a double throw switch so that I could monitor both tanks individually. Then from the fuel selector valve I ran a tube to the facet fuel pump that I secured to the cross tubes behind the jump seat. Worth what you paid for it, Larry ________________________________ Message 4 _____________________________________ Time: 06:34:21 PM PST US From: Richard Girard Subject: Re: Kolb-List:Stabilizer Angle I shimmed the elevator so that it aligned with the pivot bolt. That eliminated the small up and down movement of the horizontal stabilizer. Rick On Wed, Aug 22, 2018 at 6:48 AM, John Hauck wrote: > Rick G/Kolbers: > > > Elevator hinges are very difficult to mount exactly centered. The result > is a little fore and aft motion of the horizontal stabilizer. How do you > compensate for that fore and aft movement with tail boom gap seals? > > > john h > > mkIII > > Titus, Alabama > > > *From:* owner-kolb-list-server@matronics.com [mailto:owner-kolb-list- > server@matronics.com] *On Behalf Of *Richard Girard > *Sent:* Tuesday, August 21, 2018 11:01 AM > *To:* kolb-list@matronics.com > *Subject:* Re: Kolb-List:Stabilizer Angle > > When you do get the HS where you want it, consider making seals for the > gap between the HS and the boom tube. If it responds like the Mk III you' ll > find the rudder effectiveness much improved, to the point that you can > level the wings while in a stall just like a 172, something a stock Mk II I > will not do. > > > Rick Girard > > -- =9CBlessed are the cracked, for they shall let in the light.=9D Groucho Marx ________________________________ Message 5 _____________________________________ Time: 06:44:25 PM PST US From: Richard Girard Subject: Re: Kolb-List:Stabilizer Angle Part of the PFH experience was to qualify it for a higher maximum take off weight. With me and four 80 lb bags of cement I flew it at 1280 lb. Part of the qualification was to establish its handling in a stall. I climbed the aircraft to 4000 ft. slowed it to stall and held it there. Descent rate was somewhere north of 1000 ft per minute. I held it for over 1000 ft using only the rudder to keep the wings level. As I said, just like I did it in a 172. Before I put the seals on the horizontal stabilizer I was unable to do that at normal loading. If I recall this was noted by Rev. Pike in his Mk III as well. Rick On Wed, Aug 22, 2018 at 5:35 PM, John Hauck wrote: > > As I has said many times, the Kolb is the epitome of drag. Lift struts a nd > a 4 inch faring on the windshield did more than anything else on my FS. > After that, forget it. On the other hand fat tires/small tires made no > difference. I flew one Alaska flight with 6x6 tires and the next with 8x 6. > Absolutely no difference. > > john h > mkIII > Titus, Alabama > > > -----Original Message----- > From: owner-kolb-list-server@matronics.com > [mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard Pike > Sent: Wednesday, August 22, 2018 12:38 PM > To: kolb-list@matronics.com > Subject: Re: Kolb-List:Stabilizer Angle > > > > The only reason I gap sealed my stab to the boom tube was to possibly cut > down on drag. > Nothing changed. > > -------- > Richard Pike > Kolb MKIII N420P (420ldPoops) > Kolb Firefly Part 103 legal (Today we paint the fabric repair and fix the > nose bowl) > Kingsport, TN 3TN0 > > Forgiving is tough, being forgiven is wonderful, and God's grace really i s > amazing. > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=482632#482632 > > =========== =========== =========== =========== =========== > > -- =9CBlessed are the cracked, for they shall let in the light.=9D Groucho Marx ________________________________ Message 6 _____________________________________ Time: 07:18:12 PM PST US Subject: Kolb-List: Re: First short XC Flight and Slow Cruise Speed From: "Richard Pike" I am thinking that a big part of the problem is that you done enough variations from the norm that trying to analyze for a specific problem is going to be tough, but here's an idea: Go ahead and take an absolute boatload of pictures of your airplane, resize them, and post them in a size that will take up a normal full screen so that we can all see the details. Your descriptions are good, but a picture really is worth a thousand words. Maybe one of us will spot something. -------- Richard Pike Kolb MKIII N420P (420ldPoops) Kolb Firefly Part 103 legal (Today we paint the fabric repair and fix the nose bowl) Kingsport, TN 3TN0 Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing. 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