---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Tue 08/14/18: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:46 AM - Re: Stabilizer Angle (Ducati SS) 2. 06:48 AM - Re: Stabilizer Angle (Denny Baber) 3. 06:49 AM - Re: Stabilizer Angle (Denny Baber) 4. 08:23 AM - Re: Stabilizer Angle (Rex Rodebush) 5. 08:28 AM - Re: Stabilizer Angle (Jerry-TS-MkII) 6. 08:41 AM - Re: Photo Sizes (Stuart Harner) 7. 09:08 AM - Re: Photo Sizes (John Hauck) 8. 11:33 AM - Re: Stabilizer Angle (Bill Berle) 9. 05:01 PM - Bill's CG (Bill Berle) 10. 05:43 PM - Re: Stabilizer Angle (Rex Rodebush) ________________________________ Message 1 _____________________________________ Time: 05:46:06 AM PST US Subject: Re: Kolb-List:Stabilizer Angle From: "Ducati SS" Saw a 377 powered Firestar at the local airport with the same mod.My Firefly requires considerable forward stick for level flight though all other flight characteristics are wonderful. I did shorten the boom by 8". Read this topic online here: http://forums.matronics.com/viewtopic.php?p=482385#482385 ________________________________ Message 2 _____________________________________ Time: 06:48:14 AM PST US From: Denny Baber Subject: Re: Kolb-List: Kolb-List:Stabilizer Angle Instead of adding weight for CoG we would calculate where the battery should be to be in the middle of CoG. It is usually easy to move the battery and doesn't add any weight. It also helped the trim problem. Respectfully, Dennis Baber Cape Coral, Fl baberdk@gmail.com 305-814-7218 Stay Curious ________________________________ Message 3 _____________________________________ Time: 06:49:06 AM PST US From: Denny Baber Subject: Re: Kolb-List: Kolb-List:Stabilizer Angle Yes, the opposite of lift is gravity but if you want to fly slow you increase the angle of attack. It will make you fly slower up to around 16 degrees. Respectfully, Dennis Baber Cape Coral, Fl baberdk@gmail.com 305-814-7218 Stay Curious ________________________________ Message 4 _____________________________________ Time: 08:23:03 AM PST US Subject: Re: Kolb-List:Stabilizer Angle From: "Rex Rodebush" Bill, Have been following this thread and will make a few comments. I have a Mark III Xtra so it may be a apple and oranges comparison. My Kolb has to be flown all the time. Even if I trim it up as best I can, if I let go of the stick after about 3 or 5 seconds it will go up, down, right or left and I have to lightly regain control. I don't think Kolbs are like 172's where you can trim them up and then read a book. My air speed indicator was off about 15 mph on the first flight. With a lot of speed runs and modifications to the pitot and static locations was able to get it very true to actual airspeed. Your 5 mph "high stall speed" could very well be instrument error. When I'm landing I use up and/or down stick as required to keep it in the 3 point attitude (same as when sitting on the ground) and bring it down to just above the runway. The Kolb will slow down, stall and land, almost automatically. I'm now flying right at the aft CG "limit", maybe even a 1/4" past it or so. I don't think this is unusual from other comments in the past on the list. It flies fine. I use the flaps slightly down for trim solo and the the standard trim for nose up with a passenger. I weigh now about 155-160 lbs. When I was 35 lbs heaver I don't think I bothered with the down trim. I don't know how stiff your wing is in torsion but I can't believe aileron loading would move my Xtra wing any significant distance. Put a digital level on your wing and try to twist it. Just my general ramblings. Always worth what you paid for them. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=482392#482392 ________________________________ Message 5 _____________________________________ Time: 08:28:38 AM PST US Subject: Re: Kolb-List:Stabilizer Angle From: "Jerry-TS-MkII" <12flybellaire@gmail.com> Just a few more comments... I don't have Kolb flight experience.. but if I had a choice between a plane that required several lbs of forward stick to maintain level flight, versus tip wash out, I'd want to have a neutral stick (or close). I've not seen your CG% numbers, but you said "they were within specs", but also mentioned a 43% reward range. (Which everyone else seems to agree is way too far aft). WHAT is your CG% of MAC (full chord)? Maybe I missed reading a post, but THAT should be something you can verify from your paperwork, or that you SHOULD know!! Easiest mod? Adding some nose weight, just to see if that helps. Drooping the ailerons? Also a easy adjustment. And consider this RE tip wash out: if you adjust the aileron trail downwards, they too act like trim tabs.. and they can (and will) slightly twist the wing by doing so, into a wash out angle. It might be hard to measure or observe, but down aileron will twist the wing (and reduce the angle of attack slightly). That could be the answer you seek, re washout. It could also be a partial resolution to stick force issues. On a early post about this plane, you mentioned bent tubes, and "He ran into something". Your plane may not be "aligned" via the building fixture at Kolb, but instead tweaked by some "other input". (One aspect of buying used). As for less forward pressure at landing. Your airspeed is much reduced, your power is much reduced, and you are in ground effect. The elevator is much less effective at the slower speeds, and you are "wanting" to basically stall the plane at touchdown. I find nothing surprising about needing aft stick at that point. It's not the primary concern RE your stick forces. You may consider having your engineer friend evaluate the lift generated by the flat horizontal stab, at your starting point, and the exaggerated angle too (at various speeds). And then revise the stab airfoil, and re-run the numbers. A lifting stab keeps a plane flat(er) at high speeds. One possibility, if all else is unsatisfactory. Building a R/C model might be a good way to evaluate that possible mod. You and I may be the only two on the Kolb list, who agree.. you SHOULD be able to let go of the control stick, and it flys straight and level. Mine will have a adjustable trim tab, which alone could fly the plane if needed. And not a bungee on the stick or a sore arm!! LOL Jerry TS MKII Read this topic online here: http://forums.matronics.com/viewtopic.php?p=482393#482393 ________________________________ Message 6 _____________________________________ Time: 08:41:44 AM PST US From: "Stuart Harner" Subject: RE: Kolb-List: Photo Sizes Depending on what you are using to view the photos. Email programs such as Outlook or Windows Mail? Or are you using a web browser and viewing the list messages online? If you are looking online there are a lot of variables that can affect how images are displayed. In most browsers all you have to do is put the cursor in the image, hold down CNTRL and use either the "-" or "+" buttons or use the scroll wheel on the mouse to adjust the image or the entire web page. This works for most browsers and some email programs in the Windows, Android and some Linux environments. Don't ask me about Apple, I have no experience with that platform. For me, I have all the list postings coming to me in email. Outlook sorts them into folders and when I display a message with an attachment it appears as a link at the bottom of the message. Clicking on the link opens the file in my browser (Firefox). Once there it is rarely big enough to need scrolling. If it is I just CNTRL - Mouse Wheel it down until I can see it all. A couple of other things to keep in mind. If you take a picture with large resolution and save it to your computer, then click on it and send it using email, at least in Windows, it will prompt you to resize the image. If you start the email and then attach the file, it gets sent at full size. The same thing happens if you are online and posting to the list via a browser. You would have to use some program to resize before sending. If you have a phone that is web or email capable, most apps don't do a resize and most take pictures at fairly high resolution so you get large file sizes. I have an app on my Windows 10 phone that allows me to resize and save under a different name so that it is easy to send photos that are downsized, but you lose resolution when you do that. Since most of my contacts have good ISP bandwidth and computers less than 10 years old, I don't bother resizing. For the few that large images cause problems for, I do the resize before sending. If anyone needs help with this stuff contact me off list with information about how you view Kolb List messages, and your computer setup and I will try to help you out. Stuart -----Original Message----- From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of John Hauck Sent: Monday, August 13, 2018 7:30 PM Subject: Kolb-List: Photo Sizes I don't seem to have the same problem as Richard. All photos are downloaded and posted the correct size. I think most computers, now days, do that. Every once in a while I get a "lopper" that flows right off the margins and I can't make heads nor tails about it. In that case I don't look at it. If it is important I'll contact the sender and ask him to resize and resend me a copy if he wants me to see it. Check and see why your computer is not automatically resizing. I know I can't have the only computer, actually two computers, that resize. john h mkIII Titus, Alabama Even though Frankd does not have Image Resizer (poor chap - blew the page dimensions all to pot wit da giant pitchur) https://www.bricelam.net/ImageResizer/ he does bring up a good point: if your wing and your horizontal stab have the wrong angle between them, it causes problems. -------- Richard Pike ________________________________ Message 7 _____________________________________ Time: 09:08:21 AM PST US From: "John Hauck" Subject: RE: Kolb-List: Photo Sizes Thanks for the info, Stuart. I will surely holler if I get in a bind with my photo size. john h mkIII Titus, Alabama If anyone needs help with this stuff contact me off list with information about how you view Kolb List messages, and your computer setup and I will try to help you out. Stuart ________________________________ Message 8 _____________________________________ Time: 11:33:32 AM PST US From: Bill Berle Subject: Re: Kolb-List:Stabilizer Angle To answer a few more questions: I had made up a 9 degree plywood wedge with a bubble level taped to it. This was held underneath the wing surface at several locations on both wings during the weight and balance process. My Firestar plans say clearly that the wing needs to be at 9 degrees for the weight and balance. It was. The reason I had a real aero engineer there in the first place is because I am not completely proficient to do a proper weight and balance. I learned it many years ago at A&P mechanic school, but I have have never had to do it since then because I am not a working A&P mechanic. I have no idea what the angle between the wing and the fuselage is. Part of this is because I don't know what part of the fuselage you are supposed to measure for that. If there is a specific place where that measurement is taken then I will take that measurement and report it to the group. But there are no visible modifications to the upper fuselage cage, no weld repairs, no bent tubes, etc. It certainly does not look like it was rebuilt or changed in that area. Kolbs have various different "angle of incidence" for the wings depending on which model and what the use for the airplane is. The Slingshot had a much lower incidence angle on the same basic wing because it was supposed to be a much faster aircraft. Kolb adjusted the angles of wing, fuselage, and tail in many many different variations. You can easily see this just by looking at the photos of the flying aircraft. Because of the Kolb's unique wing folding hinge, the only thing they had to do to adjust the angle of incidence in most cases was to drill the bolt hole in the wing root fitting higher or lower. Then they adjusted the stabilizer angle to provide the proper amount of decalage angle between the wing and tail. This allowed Kolb to experiment and customize the same basic components into many different models over the years. Very clever and it worked well. In my case I cannot (and should not) re-drill the hole in the root fitting. My aircraft had badly worn oval bolt holes in this fitting, and I repaired it by bolting reinforcement doublerplates to either side of the fitting. This gives me essentially a new hole in new metal, and I still have the old hole and old metal as a backup. Safe and strong. But I cannot simply drill a new hole because the reinforcements and fasteners are there. There is very little torsional movement in the leading edge of the ailerons. I held the root end of the control arm and a friend of mine held the tip of the aileron, and we twisted it. It was pretty stiff, not "springy" at all. I also looked at the ailerons in flight, and when I moved them the inboard and outboard ends of the ailerons were both at the same angle... littleor no twisting of the aileron itself in flight. I am going to get the original weight and balance calculations this week, and I wil post exactly what we found. Then I will have a calculation done on where the CG is with my current body weight,a and see if my weight loss has thrown the aircraft out of the Kolb approved range. Bill Berle www.ezflaphandle.com - safety & performance upgrade for light aircraft www.grantstar.net - winning proposals for non-profit and for-profit entities ________________________________ Message 9 _____________________________________ Time: 05:01:33 PM PST US From: Bill Berle Subject: Kolb-List: Bill's CG On the day this aircraft was weighed, the Center of Gravity worked out to 32% of chord. We first measured the chord both for the wing section with the aileron, and then the section without the aileron. Our decision on which wing chord to use for CG purpsoes was based on the fact that the wing makes more of its lift toward the center of the wing than it does at the outboard section. This is why all the textbooks have what is called the "elliptical shaped lift distribution". The amount of lift it makes gets smaller the further outboard you travel along the wingspan. However, on a Kolb, the outboard half of the wing has more area, because there is an 11 or 12 inch aileron there. So you could make an argument that the Kolb will have a little more lift outboard than a J-3 Cub, and as such it will not have as smooth and elliptical of a lift distribution as a textbook J-3 Cub wing. But it still will make a little more lift on the inboard half than it will on the outboard half, because the lift HAS TO taper down to zero at the tip itself. So the AVERAGE of the wing lift will be a little bit more centered on the inboard half of the wing than it would be on the outboard half. So we used the inboard section of the wing as the "chord" when we determined what the "percentage of chord" was, because a little more of the lift is made there. This is also the conservative safe thing to do, because even if we were wrong, it would be an error on the safe side. To explain, iIf we had a CG of 32% as measured on the inboard chord, but we should have been measuring the outboard chord instead, the same balance point on the wing surface (X number of inches behind the leading edge) would wind up being a slightly smaller percentage of the outboard chord. Now, 32% of the inboard chord is still well forward of the maximum 37% as specified in the Kolb plans. Again, even if we plotted this out on the wrong section of wing, it would have represented LESS than 32% of the correct chord. Tomorrow we are going to go through the actual numbers again, and do the math again, and make sure we are including all the fuel, and my "new and improved" body weight. But at this stage it seems unlikely that the aircraft was WAY OUT of the safe CG range. Bill Berle www.ezflaphandle.com - safety & performance upgrade for light aircraft www.grantstar.net - winning proposals for non-profit and for-profit entities ________________________________ Message 10 ____________________________________ Time: 05:43:04 PM PST US Subject: Re: Kolb-List:Stabilizer Angle From: "Rex Rodebush" When I set up my wing I called Brian at TNK. He gave me the recommended wing and horizontal stabilizer angles in reference to the motor mounts. ie, get a digital level, set it on the motor mounts and zero it, then check both wings at several points and average the results. Same for the stabilizer. I would call Brian and get the angles for your model. Where you have your stabilizer now is so far from everyone else that something is definitely wrong. 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