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mdnanwelch7(at)hotmail.co
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 Posted: Mon Feb 11, 2008 3:59 pm Post subject: Wing Incidence and AOA on a MkIII |
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Gang,
With all this AOA (wing incidence) talk lately, I thought I'd hang my wings on the fuselage for the first time in at least 8 years!!!
A little background for those that care. I bought this MkIII C from Kolb back in Nov 98. I worked on it for about a year and was almost finished with the plane itself, with only the fabric left to complete. Fuselage was covered, panel and gauges finished, all frame components and flight controls hooked up and functional. Engine and propeller fully running.
Life, and a couple of moves got in the way, and I wasn't able to finish. Add to this that I bought a GlaStar to work on, and the poor MkIII really "doesn't get any respect!!" (Became the main candidate for the back-burner!)
Fortunately, life has given me a chance to play with the Kolb for a year. Last June, I decided before I proceed any further forward with the MkIII Classic, I elected to do a major "make-over"....and convert my MkIII into an Xtra (or a reasonable facsimile).
Back to the present; after hanging the wings today, and using my NEW SUPER- DUPER DIGITAL LEVEL, it appears as though my wings may be set at about 8 degree incidence. Rereading the book (after blowing off the dust), double checking my results, and really pondering where I went wrong, I think I have found the culprit!!
It's not the wings at all, but it is the tailfeathers. It appears that the leading edge of the horizontal stabilizers are attached to the boom-tube a tad bit too high.
Why does this matter? Because to take the "wing incidence" reading, you are supposed to "level" the horizontal stabilizers......and the more the stabilizers are "too high" in front.....the more you have to raise the tail, to level them. The more you raise the tail...the less the incidence on the main wings.
So, it appears in my case I do one of two things:
1) Don't sweat it, crappy quality is always acceptable when it comes to airplanes, especially if you fly them personally
or
2) Drill out and remove those big rivets, and remount the leading edges of the hor. stabs where it should have been in the first place
Gee, which should it be? I think I'll drill out those monsterous rivets, and do it right. Only this time, I'll have a digital level to make sure it's gnat's patootey close, before I drill holes.
I'm going on the assumption that whoever said Homer designed the incidence right knew what he was talking about. Otherwise, option 1) is so much easier to live with...kind of like the "horseshoes and hand grenades" simile.
Mike Welch Kolb MkIII CX
Do Not Archive
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Shed those extra pounds with MSN and The Biggest Loser!
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jindoguy(at)gmail.com
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| Posted: Mon Feb 11, 2008 5:49 pm Post subject: Wing Incidence and AOA on a MkIII |
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Mike, before drilling out any rivets, check with TNK. It seems to me that the MkIIIX they had on display at Sun n Fun had new brackets for attaching the horizontal stabilizer that had three holes for trim adjustment. I could be wrong, it's been almost a year.
Next I went out to the hangar and checked how my horizontal stab relates to my wings when the bottom is at 9 degrees. The horizontal stab is 2 degrees 40 minutes up at the leading edge of the stab. Mine flies just fine and has no problem rotating for take off. I don't think you have a problem. Fly it first and then make changes if you need to. I think you'll be fine.
Rick
On Feb 11, 2008 5:56 PM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
[quote] --> Kolb-List message posted by: Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)>
Gang,
With all this AOA (wing incidence) talk lately, I thought I'd hang my wings on the fuselage for the first time in at least 8 years!!!
A little background for those that care. I bought this MkIII C from Kolb back in Nov 98. I worked on it for about a year and was almost finished with the plane itself, with only the fabric left to complete. Fuselage was covered, panel and gauges finished, all frame components and flight controls hooked up and functional. Engine and propeller fully running.
Life, and a couple of moves got in the way, and I wasn't able to finish. Add to this that I bought a GlaStar to work on, and the poor MkIII really "doesn't get any respect!!" (Became the main candidate for the back-burner!)
Fortunately, life has given me a chance to play with the Kolb for a year. Last June, I decided before I proceed any further forward with the MkIII Classic, I elected to do a major "make-over"....and convert my MkIII into an Xtra (or a reasonable facsimile).
Back to the present; after hanging the wings today, and using my NEW SUPER- DUPER DIGITAL LEVEL, it appears as though my wings may be set at about 8 degree incidence. Rereading the book (after blowing off the dust), double checking my results, and really pondering where I went wrong, I think I have found the culprit!!
It's not the wings at all, but it is the tailfeathers. It appears that the leading edge of the horizontal stabilizers are attached to the boom-tube a tad bit too high.
Why does this matter? Because to take the "wing incidence" reading, you are supposed to "level" the horizontal stabilizers......and the more the stabilizers are "too high" in front.....the more you have to raise the tail, to level them. The more you raise the tail...the less the incidence on the main wings.
So, it appears in my case I do one of two things:
1) Don't sweat it, crappy quality is always acceptable when it comes to airplanes, especially if you fly them personally
or
2) Drill out and remove those big rivets, and remount the leading edges of the hor. stabs where it should have been in the first place
Gee, which should it be? I think I'll drill out those monsterous rivets, and do it right. Only this time, I'll have a digital level to make sure it's gnat's patootey close, before I drill holes.
I'm going on the assumption that whoever said Homer designed the incidence right knew what he was talking about. Otherwise, option 1) is so much easier to live with...kind of like the "horseshoes and hand grenades" simile.
Mike Welch Kolb MkIII CX
Do Not Archive
_________________________________________________________________
Shed those extra pounds with MSN and The Biggest Loser!
http://biggestloser.msn.com/
[quote][b]
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rowedenny(at)windstream.n
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| Posted: Mon Feb 11, 2008 11:18 pm Post subject: Wing Incidence and AOA on a MkIII |
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| Quote: | I'm going on the assumption that whoever said Homer designed the
incidence right knew what he was talking about. Otherwise, option 1) is
so much easier to live with...kind of like the "horseshoes and hand
grenades" simile.
Mike Welch Kolb MkIII CX
Do Not Archive
|
Mike,
I am the one who said that Homer got it right, but I agree with Richard
Girard that you are probably close enough, after all no one had digital
levels when Homer built his first plane. These birds are not as critical as
an F-22 so I'm quite sure your plane will fly as advertised.
If it needs a little fine tuning, you can always install the adjustable
front mounts later.
Denny Rowe
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JVanLaak(at)aol.com
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| Posted: Tue Feb 12, 2008 4:04 am Post subject: Wing Incidence and AOA on a MkIII |
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Guys,
I am new to this list but built one of the first Firestars back in 89. Loved the plane and frankly wish I had one now.
The point to watch in this discussion is probably less the incidence of the wing than the trim of the tail. The pitch attitude of the airplane will be dominated by the incidence of the wing but as has been said you will hardly notice the difference except for when you lift off on takeoff.
But the trim difference could be a little more problematic and it is driven by the difference in incidence between the wing and tail. I don't quite remember the last post but if the leading edge of the stabilizer was too high relative to the wing it would mean less nose up power. There is lots of tail power in most kolbs but if a non-standard engine is used or some other non-standard element sneaks in there is the potential for a surprise.
If on the other hand, the angle between the tail and wing agree there is little problem and I agree that changing it is probably not mandatory, but I would want to think about all implications. It would be good to be back in the middle of the designers box.
Jim Van Laak
The year's hottest artists on the red carpet at the Grammy Awards. AOL Music takes you there.
[quote][b]
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JetPilot
Joined: 10 Jan 2006
Posts: 1246
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| Posted: Tue Feb 12, 2008 10:09 am Post subject: Re: Wing Incidence and AOA on a MkIII |
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When I talked to Kolb last time, they gave me all the correct incidence values from the engine mount being level. Then you can measure wings, tail, and boom incidence.
The new MK III 's have a 4 hole adjustable front attachment for the leading edge of the horizontal stab. Talk to Kolb, make sure you have the correct values, and if you do decide to drill that out, put the adjustable bracket on your boom. That way you wont be redrilling a bunch of times if the trim of your plane does not work out exactly as planned, you just change the hole the leading edge attaches to.
Mike
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