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MkIII Xtra

 
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Mike Welch



Joined: 13 Feb 2011
Posts: 272

PostPosted: Mon Jun 06, 2011 5:44 am    Post subject: MkIII Xtra Reply with quote

Rick G,

� Recently you mentioned you were test flying Ken's Xtra that you just
finished working on.� Evidently it had "lawn dart syndrome".� Did you
ever get it figured out, and if so, what was the final horizontal stabilizer's
position that you settled on?

Mike Welch
MkIII N212MN
[quote][b]


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rickofudall



Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

PostPosted: Mon Jun 06, 2011 11:13 am    Post subject: MkIII Xtra Reply with quote

As of the last flight when I had the horizontal stabilizer lowered to lowest position that the bracked would allow and I was slowly adjusting the flaps and ailerons to make sure they were neutral to slightly reflexed. There was some improvement, but if I let go of the stick the nose would still begin to drop. I was out of adjustment on the flap pushrods, so I put the plane away for the night and began taking measurements. Wings s/b 2.8 to 3.4 degrees, are 3.45 and 3.75 degrees, horizontal stabilizer s/b -6.1 degrees, is -6.9 degrees.�This is all referenced to the engine mount set at 0.
Out of curiosity I measured the bottom of the cockpit at the nose cone and at two points aft of it. Those angles were 2.9 degrees at the nose cone, 1.1 degrees just aft of the nose cone, and -1.75 degrees on the center longeron approximately even with the pilots seat.
The next morning I called Spruce to get some tubing for new flap push rods and then to Bryan Melbourne for his take on the situation. Bryan convinced me that the wing incidence had to be lowered to the least limit and I spent a couple of days trying to find a welder with a portable TIG. When that didn't happen I came up with a way to fill the holes and attach a plate to either side of the wing bracket.�
The amount of lowering needed amounted to .375" on the right wing and .500" on the left. I machined a plate for the forward side of the plate from 3/8" 4130 so that it was .11" thick with a 3/8" boss sticking up .25". The boss would go through the old mount hole. The plate on the aft side is 3/16" 4130 and has counter sinks at the bolt holes for the boss on the fore plate and the bushing I put through the original IIIC mount hole. The plates are attached with J B Weld and two NAS flat head bolts on each wing.
On the spar carry through on the fuselage, I drilled the holes out to 7/16" and made flanged bushings that are a press fit. To seal the area under the head I used J B Weld again.
So, at this point, the wings are back on and the new flap push rods are made and installed. The old gap seal, which only fit in a token manner before, now doesn't fit at all. I was hoping to fly this morning before the wind picked up and the thermals began popping off, but I decided to rework the gap seal and hope for light winds tomorrow morning at dawn.
To Mark IIIX builders,�you may notice from the pictures how high up the wing mount holes are on the spar carry through tabs and the wing tabs. The IIIX requires the wings to be mounted at such low incidence that you can run out of tab if you are not careful. If the holes had been located in the center of the spar carry through tabs more edge margin would have been available on the wing tabs. When you mount the wings, try to make the holes in the spar carry through in the center of the tabs or slightly lower than center.


Rick Girard

On Mon, Jun 6, 2011 at 8:41 AM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:
Rick G,

� Recently you mentioned you were test flying Ken's Xtra that you just
finished working on.� Evidently it had "lawn dart syndrome".� Did you
ever get it figured out, and if so, what was the final horizontal stabilizer's
position that you settled on?

Mike Welch
MkIII N212MN
Quote:


get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution



--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


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Mike Welch



Joined: 13 Feb 2011
Posts: 272

PostPosted: Mon Jun 06, 2011 1:18 pm    Post subject: MkIII Xtra Reply with quote

Rick,

� Nice job of relocating the wing's tab holes & tabs.

� IIRC, and I�do, your reference to the hor. stabs angle of -6.1 is wrong.� That is the boomtube's
angle.� The hor. stabs are supposed to be -4.6.� Of course, we're ALWAYS referencing that
starting point of "0" degrees for the motor mount.

� I have a chart�I put together a couple of�years ago that has all kinds of various angles for the
Xtra.��But, I put this chart together before I knew that the motor mount had to be leveled, so for
lack of any better idea, I asked the guys to set their main wings at "9" degrees.�
� After I�built the chart, I found out later that Xtra's are advised to use a precise angle setting
procedure.� My chart doesn't have much value anymore, since Kolb Co. has a specific plan
to address angles and incidences.� (yay!)

��Regarding your hor stabs ACTUALLY�being -6.9....something's screwed!!� No bleeping way!!
Not unless Kolb Co. is handing out new angle numbers!!

� When�I talked to Bryan Melbourne�about how to go about setting up the plane (as an Xtra), he
said;
1) set motor mount to pure level (left & right, & for and aft)
2) boom tube SHOULD�come in at�-6.1 (mine was spot on!)
3) main wing are to be set at +3.4 degrees.�
����������� (I have later found out that +2.8 was also 'suggested'.
������������So +2.8 to +3.4 is the acceptable range.�
��������������������� (Mine are 3.4.......exact!)
4)horizontal stabs are to be set at -4.6 degrees.�
������������ (I have adjustable mounts� that will let them vary
��������������from about -4.0 to -5.5 degrees.)
5) dihedral "should be" around +1.6 degrees���
���������������(Since my wings were already mounted years ago,
���������������I decided NOT to change the struts lengths,�so this had the
���������������effect of creating more dihedral than the stock Xtra's
���������������OEM recommended angle.� I ended up with +2.7 degrees
���������������dihedral)

� You ought to call Bryan and verify that horizontal stabilizer number!

� It looks like you're well on your way to getting this thing ironed out.� Good job.

Mike Welch






Date: Mon, 6 Jun 2011 14:10:28 -0500
Subject: Re: MkIII Xtra
From: aslsa.rng(at)gmail.com
To: kolb-list(at)matronics.com

As of the last flight when I had the horizontal stabilizer lowered to lowest position that the bracked would allow and I was slowly adjusting the flaps and ailerons to make sure they were neutral to slightly reflexed. There was some improvement, but if I let go of the stick the nose would still begin to drop. I was out of adjustment on the flap pushrods, so I put the plane away for the night and began taking measurements. Wings s/b 2.8 to 3.4 degrees, are 3.45 and 3.75 degrees, horizontal stabilizer s/b -6.1 degrees, is -6.9 degrees.�This is all referenced to the engine mount set at 0.
Out of curiosity I measured the bottom of the cockpit at the nose cone and at two points aft of it. Those angles were 2.9 degrees at the nose cone, 1.1 degrees just aft of the nose cone, and -1.75 degrees on the center longeron approximately even with the pilots seat.
The next morning I called Spruce to get some tubing for new flap push rods and then to Bryan Melbourne for his take on the situation. Bryan convinced me that the wing incidence had to be lowered to the least limit and I spent a couple of days trying to find a welder with a portable TIG. When that didn't happen I came up with a way to fill the holes and attach a plate to either side of the wing bracket.�
The amount of lowering needed amounted to .375" on the right wing and .500" on the left. I machined a plate for the forward side of the plate from 3/8" 4130 so that it was .11" thick with a 3/8" boss sticking up .25". The boss would go through the old mount hole. The plate on the aft side is 3/16" 4130 and has counter sinks at the bolt holes for the boss on the fore plate and the bushing I put through the original IIIC mount hole. The plates are attached with J B Weld and two NAS flat head bolts on each wing.
On the spar carry through on the fuselage, I drilled the holes out to 7/16" and made flanged bushings that are a press fit. To seal the area under the head I used J B Weld again.
So, at this point, the wings are back on and the new flap push rods are made and installed. The old gap seal, which only fit in a token manner before, now doesn't fit at all. I was hoping to fly this morning before the wind picked up and the thermals began popping off, but I decided to rework the gap seal and hope for light winds tomorrow morning at dawn.
To Mark IIIX builders,�you may notice from the pictures how high up the wing mount holes are on the spar carry through tabs and the wing tabs. The IIIX requires the wings to be mounted at such low incidence that you can run out of tab if you are not careful. If the holes had been located in the center of the spar carry through tabs more edge margin would have been available on the wing tabs. When you mount the wings, try to make the holes in the spar carry through in the center of the tabs or slightly lower than center.


Rick Girard

On Mon, Jun 6, 2011 at 8:41 AM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:
Rick G,

� Recently you mentioned you were test flying Ken's Xtra that you just
finished working on.� Evidently it had "lawn dart syndrome".� Did you
ever get it figured out, and if so, what was the final horizontal stabilizer's
position that you settled on?

Mike Welch
MkIII N212MN
Quote:


get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution



--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM


It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


[quote][b]


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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rickofudall



Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

PostPosted: Mon Jun 06, 2011 3:00 pm    Post subject: MkIII Xtra Reply with quote

Mike, All I can tell you is that the horizontal stabs are now set right down the center of the boom. I started out with them in the upper most hole of the bracket and moved them down in steps to try and relieve the nose heaviness. Lower was better in each step to the lowest position. It was Bryan that suggested I lower the wings to the lowest setting. I was concerned about being able to get the aircraft to rotate. He assured me that he had welded up holes before that were drilled so as to set the wing incidence too high and it had fixed the problem.
Since I have the CG at the almost the farthest aft position, 34.28% (I use 35% as most aft), and I'm running the trim in the most up position, I don't think less horizontal stabilizer incidence is the way to go.
The nice thing about having a flying aircraft is that theory can be tested against reality PDQ. With any luck, I'll know in the morning.
Rick

On Mon, Jun 6, 2011 at 4:15 PM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:
Rick,

� Nice job of relocating the wing's tab holes & tabs.

� IIRC, and I�do, your reference to the hor. stabs angle of -6.1 is wrong.� That is the boomtube's
angle.� The hor. stabs are supposed to be -4.6.� Of course, we're ALWAYS referencing that
starting point of "0" degrees for the motor mount.

� I have a chart�I put together a couple of�years ago that has all kinds of various angles for the
Xtra.��But, I put this chart together before I knew that the motor mount had to be leveled, so for
lack of any better idea, I asked the guys to set their main wings at "9" degrees.�
� After I�built the chart, I found out later that Xtra's are advised to use a precise angle setting
procedure.� My chart doesn't have much value anymore, since Kolb Co. has a specific plan
to address angles and incidences.� (yay!)

��Regarding your hor stabs ACTUALLY�being -6.9....something's screwed!!� No bleeping way!!
Not unless Kolb Co. is handing out new angle numbers!!

� When�I talked to Bryan Melbourne�about how to go about setting up the plane (as an Xtra), he
said;
1) set motor mount to pure level (left & right, & for and aft)
2) boom tube SHOULD�come in at�-6.1 (mine was spot on!)
3) main wing are to be set at +3.4 degrees.�
����������� (I have later found out that +2.8 was also 'suggested'.
������������So +2.8 to +3.4 is the acceptable range.�
��������������������� (Mine are 3.4.......exact!)
4)horizontal stabs are to be set at -4.6 degrees.�
������������ (I have adjustable mounts� that will let them vary
��������������from about -4.0 to -5.5 degrees.)
5) dihedral "should be" around +1.6 degrees���
���������������(Since my wings were already mounted years ago,
���������������I decided NOT to change the struts lengths,�so this had the
���������������effect of creating more dihedral than the stock Xtra's
���������������OEM recommended angle.� I ended up with +2.7 degrees
���������������dihedral)

� You ought to call Bryan and verify that horizontal stabilizer number!

� It looks like you're well on your way to getting this thing ironed out.� Good job.

Mike Welch






Date: Mon, 6 Jun 2011 14:10:28 -0500
Subject: Re: MkIII Xtra
From: aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)

As of the last flight when I had the horizontal stabilizer lowered to lowest position that the bracked would allow and I was slowly adjusting the flaps and ailerons to make sure they were neutral to slightly reflexed. There was some improvement, but if I let go of the stick the nose would still begin to drop. I was out of adjustment on the flap pushrods, so I put the plane away for the night and began taking measurements.
Wings s/b 2.8 to 3.4 degrees, are 3.45 and 3.75 degrees, horizontal stabilizer s/b -6.1 degrees, is -6.9 degrees.�This is all referenced to the engine mount set at 0.
Out of curiosity I measured the bottom of the cockpit at the nose cone and at two points aft of it. Those angles were 2.9 degrees at the nose cone, 1.1 degrees just aft of the nose cone, and -1.75 degrees on the center longeron approximately even with the pilots seat.
The next morning I called Spruce to get some tubing for new flap push rods and then to Bryan Melbourne for his take on the situation. Bryan convinced me that the wing incidence had to be lowered to the least limit and I spent a couple of days trying to find a welder with a portable TIG. When that didn't happen I came up with a way to fill the holes and attach a plate to either side of the wing bracket.�
The amount of lowering needed amounted to .375" on the right wing and .500" on the left. I machined a plate for the forward side of the plate from 3/8" 4130 so that it was .11" thick with a 3/8" boss sticking up .25". The boss would go through the old mount hole. The plate on the aft side is 3/16" 4130 and has counter sinks at the bolt holes for the boss on the fore plate and the bushing I put through the original IIIC mount hole. The plates are attached with J B Weld and two NAS flat head bolts on each wing.
On the spar carry through on the fuselage, I drilled the holes out to 7/16" and made flanged bushings that are a press fit. To seal the area under the head I used J B Weld again.
So, at this point, the wings are back on and the new flap push rods are made and installed. The old gap seal, which only fit in a token manner before, now doesn't fit at all. I was hoping to fly this morning before the wind picked up and the thermals began popping off, but I decided to rework the gap seal and hope for light winds tomorrow morning at dawn.
To Mark IIIX builders,�you may notice from the pictures how high up the wing mount holes are on the spar carry through tabs and the wing tabs. The IIIX requires the wings to be mounted at such low incidence that you can run out of tab if you are not careful. If the holes had been located in the center of the spar carry through tabs more edge margin would have been available on the wing tabs. When you mount the wings, try to make the holes in the spar carry through in the center of the tabs or slightly lower than center.


Rick Girard


On Mon, Jun 6, 2011 at 8:41 AM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:

Quote:
Rick G,

� Recently you mentioned you were test flying Ken's Xtra that you just
finished working on.� Evidently it had "lawn dart syndrome".� Did you
ever get it figured out, and if so, what was the final horizontal stabilizer's
position that you settled on?

Mike Welch
MkIII N212MN

Quote:


get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution



--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM


It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx



Quote:


get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution




--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


[quote][b]


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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_________________
The smallest miracle right in front of you is enough to make you happy....
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Mike Welch



Joined: 13 Feb 2011
Posts: 272

PostPosted: Mon Jun 06, 2011 6:13 pm    Post subject: MkIII Xtra Reply with quote

Rick,

� I was only relaying the factory recommended numbers that Bryan says, not suggesting
a particular solution in your case.� You are infinitely more qualified to know how to handle
what your situation requires than me.� I'm just an interested observer who's trying to find
some very valuable information.

� I got lost in your explanation "He assured me that he had welded up holes before that
were drilled so as to set the wing incidence too high and it had fixed the problem."�� I did
not understand what you were getting at.��� ???

� If you have the horizontal stabs set right down the middle of the boom tube, then that means
they are essentially -6.1 degrees (or real close)�� Since there is no adjustment of the boom
tube angle of -6.1 degrees....compared to the motor mount, obviously something parallel to it
would be the same.�� Now, maybe this helps make the plane fly better, but it sure does NOT
sound like the angles I've been led to believe are correct for an Xtra.� Bryan told me those
numbers I posted.� If they don't work very well on Ken's plane, I think I'd be doing some
serious investigating.

� I still say......"sumptin's up!!"

� Maybe we could get an Xtra owner/flyer to share what his angles and W&B information is.
There's nothing like having someone tell us all what works GREAT for him.� Plus, it might
give a good indication why that stab has to be so low, compared to the OEM setting.

How about it, Xtra owners, anybody have the digital incidences and angles, and the W&B�on a
decent flying plane??

� BTW, it would seem to me that lowering the main wings' incidence down to their proper angle,
would make the plane even more nose heavy.� At least, that's how I would think it would act.
I look forward to a successful pirep!!

Mike Welch





Date: Mon, 6 Jun 2011 17:57:50 -0500
Subject: Re: MkIII Xtra
From: aslsa.rng(at)gmail.com
To: kolb-list(at)matronics.com

Mike, All I can tell you is that the horizontal stabs are now set right down the center of the boom. I started out with them in the upper most hole of the bracket and moved them down in steps to try and relieve the nose heaviness. Lower was better in each step to the lowest position. It was Bryan that suggested I lower the wings to the lowest setting. I was concerned about being able to get the aircraft to rotate. He assured me that he had welded up holes before that were drilled so as to set the wing incidence too high and it had fixed the problem.
Since I have the CG at the almost the farthest aft position, 34.28% (I use 35% as most aft), and I'm running the trim in the most up position, I don't think less horizontal stabilizer incidence is the way to go.
The nice thing about having a flying aircraft is that theory can be tested against reality PDQ. With any luck, I'll know in the morning.


Rick



[quote][b]


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rickofudall



Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

PostPosted: Tue Jun 07, 2011 7:43 am    Post subject: MkIII Xtra Reply with quote

The reference to my talk with Bryan was poorly stated for the information I was trying to convey. What I was trying to say was that lowering the wing incidence works to negate the downward pressure exerted by the "X" fuselage pod, that several builders have done them incorrectly and welding up the holes and remounting them solved the problem. So, I got up before dawn, made final adjustments to the flaps to eyeball them in to being equal side to side, and went flying. It was done sans any center gap seal at all. The wings are now so low that the old one can't be hacked up to even mount it much less offer any kind of drag reduction.
Immediately after take off I was disappointed to find that there was little improvement in pitch. As I passed over the departure end of the runway and started searching the pattern just in case someone else was up early to come visiting, I noticed that I had neglected to pull on any trim. Pulling the trim handle meant slipping out of my shoulder harness to reach it (I fly right seat) and once adjusted, which yielded a small improvement in back pressure on the stick, I couldn't refasten the buckle. This was now going to be a flight around the pattern, rather than the slightly longer one to get a little more altitude and try nudging up to stall speed to see how optimistic the airspeed indicator is, that I had planned.
Being a windy morning, I started my turn to base from abeam the runway end, made my turn and slid along at a roughly 45 degree angle to my actual direction of travel until it was time to turn final. I was quite high, but I counted on the wind gradient to give me a steep approach angle even without flaps and at 600 feet and roughly about the same from the end of the runway, I pulled the power to idle. SURPRISE!, all the back pressure went away. As a glider, the airplane is now completely neutral. Landing number seven was the most pleasant I've made in Ken's airplane. While I still kept the airspeed up to 60 indicated, I was able to relax my death grip on the stick and, for a few seconds at least, enjoy flying the aircraft.
So, the change to wing incidence seems to have alleviated the negative lift of the "platypus nose" fuselage pod and it appears I'm dealing with a thrust line issue.�
John H., if you're reading this, try not to say "I told you so". He did, by the way, so I deserve it.�
Anyway, even though the engine is 5/16" lower than the factory mounting for a 618 with the "E" gearbox, the combination of the extra height, 70" propeller, and changed thrust line from the IIIC seems to be the cause of the nose down pitch attitude.
Here are the angles as they are since I moved the wing incidence, adjusted for the motor mount being level.
Left and Right wing � � 2.8 degrees
Boom � � � � � � � � � � � �7 degrees
H Stab � � � � � � � � � � �7 degrees
There are some small changes in the readings of the boom and horizontal stabilizers since the ones I took last. I measured each twice this time, �rotating the protractor 180 degrees in the horizontal plane and taking the average of the two measurements.
As a firm believer in doing the cheapest "fix" first, I'm going to lower the front of the motor mount to change the thrust angle by the difference between the C and X wing incidence.
It's not forecast to be flyable, at least for test flying, again until Thursday at dawn so I'll know more then.

On Mon, Jun 6, 2011 at 9:10 PM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:
Rick,

� I was only relaying the factory recommended numbers that Bryan says, not suggesting
a particular solution in your case.� You are infinitely more qualified to know how to handle
what your situation requires than me.� I'm just an interested observer who's trying to find
some very valuable information.

� I got lost in your explanation "He assured me that he had welded up holes before that
were drilled so as to set the wing incidence too high and it had fixed the problem."�� I did
not understand what you were getting at.��� ???

� If you have the horizontal stabs set right down the middle of the boom tube, then that means
they are essentially -6.1 degrees (or real close)�� Since there is no adjustment of the boom
tube angle of -6.1 degrees....compared to the motor mount, obviously something parallel to it
would be the same.�� Now, maybe this helps make the plane fly better, but it sure does NOT
sound like the angles I've been led to believe are correct for an Xtra.� Bryan told me those
numbers I posted.� If they don't work very well on Ken's plane, I think I'd be doing some
serious investigating.

� I still say......"sumptin's up!!"

� Maybe we could get an Xtra owner/flyer to share what his angles and W&B information is.
There's nothing like having someone tell us all what works GREAT for him.� Plus, it might
give a good indication why that stab has to be so low, compared to the OEM setting.

How about it, Xtra owners, anybody have the digital incidences and angles, and the W&B�on a
decent flying plane??

� BTW, it would seem to me that lowering the main wings' incidence down to their proper angle,
would make the plane even more nose heavy.� At least, that's how I would think it would act.
I look forward to a successful pirep!!

Mike Welch





Date: Mon, 6 Jun 2011 17:57:50 -0500
Subject: Re: Kolb-List: MkIII Xtra
From: aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)


Mike, All I can tell you is that the horizontal stabs are now set right down the center of the boom. I started out with them in the upper most hole of the bracket and moved them down in steps to try and relieve the nose heaviness. Lower was better in each step to the lowest position. It was Bryan that suggested I lower the wings to the lowest setting. I was concerned about being able to get the aircraft to rotate. He assured me that he had welded up holes before that were drilled so as to set the wing incidence too high and it had fixed the problem.
Since I have the CG at the almost the farthest aft position, 34.28% (I use 35% as most aft), and I'm running the trim in the most up position, I don't think less horizontal stabilizer incidence is the way to go.
The nice thing about having a flying aircraft is that theory can be tested against reality PDQ. With any luck, I'll know in the morning.


Rick




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Thanks, Homer GBYM
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� - Groucho Marx


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Mike Welch



Joined: 13 Feb 2011
Posts: 272

PostPosted: Tue Jun 07, 2011 8:27 am    Post subject: MkIII Xtra Reply with quote

Rick,

� Sounds like you're on the right path.� Good luck on your next attempt to get it fixed.

� I am curious, before you change the existing thrust line, can you check what the present
angle is?�� You could probably figure an accurate way to do it, but maybe using a
large rectangle of cardboard, with your protractor taped in place 90 degrees from the
edge you line up with the prop blades.

� Aslo, can you measure the EXACT height of the�propeller centerline to the boom tube?� I'm
curious how my GEO motor prop centerline measures up against the Rotax 582.

Mike Welch
out in my shop today painting blue & yellow accent stripes��
high 90's heat and humidity is�rough!!!

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rickofudall



Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

PostPosted: Tue Jun 07, 2011 10:15 am    Post subject: MkIII Xtra Reply with quote

Mike, The thrust line, barring flex of the Lord mounts is right down the engine mount. There are no shims installed at this time. The center of the prop is 36" above the top of the boom tube.

Rick

On Tue, Jun 7, 2011 at 11:24 AM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:
Rick,

� Sounds like you're on the right path.� Good luck on your next attempt to get it fixed.

� I am curious, before you change the existing thrust line, can you check what the present
angle is?�� You could probably figure an accurate way to do it, but maybe using a
large rectangle of cardboard, with your protractor taped in place 90 degrees from the
edge you line up with the prop blades.

� Aslo, can you measure the EXACT height of the�propeller centerline to the boom tube?� I'm
curious how my GEO motor prop centerline measures up against the Rotax 582.

Mike Welch
out in my shop today painting blue & yellow accent stripes��
high 90's heat and humidity is�rough!!!

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--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


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NeilsenRM(at)gmail.com
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PostPosted: Tue Jun 07, 2011 10:29 am    Post subject: MkIII Xtra Reply with quote

Rick/AllI had a long discussion with Brian M at Sun-N-Fun before the tornado hit. He said that the early xtras had a larger horizontal stabilizer to compensate for what they later found was down pressure on the nose from flying nose low. Reducing the wing incidence fixed the problems and increased speeds. Now for the downward pitching problem I will suggest one more time that you get that trim system working properly. You may need to add a spring or change to a heaver one. Just keep playing with it till it flies level. Flying solo you should be near the low end of pitch trim adjustment so that you will have plenty more trim when you have a heavy passenger. Go ahead and play with the thrust angle but that, according to John H, it will have little impact. For best performance set the thrust angle to level in level flight. I set my trim for hands off for cruise. I fine tune the trim by adding or reducing power a bit. Kolbs with high thrust engines change the pitch trim it is the nature of the beast. I find that pitch trim at cruise power or low power with one notch of flaps on approach is about the same pitch trim. Rick NeilsenRedrive VW Powered MKIIICOn , Mike Welch <mdnanwelch7(at)hotmail.com> wrote:> > > > > > Rick,> > �> > � Sounds like you're on the right path.� Good luck on your next attempt to get it fixed.> > �> > � I am curious, before you change the existing thrust line, can you check what the present> > angle is?�� You could probably figure an accurate way to do it, but maybe using a > > large rectangle of cardboard, with your protractor taped in place 90 degrees from the > > edge you line up with the prop blades.> > �> > � Aslo, can you measure the EXACT height of the�propeller centerline to the boom tube?� I'm > > curious how my GEO motor prop centerline measures up against the Rotax 582.> > �> > Mike Welch> > out in my shop today painting blue & yellow accent stripes��> > high 90's heat and humidity is�rough!!!> �> > � > > > ======================> > > [quote][b]

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rickofudall



Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

PostPosted: Tue Jun 07, 2011 2:01 pm    Post subject: MkIII Xtra Reply with quote

Rick, So far as I can tell, without putting a force gage on the elevator, the trim system is working properly, at least compared to my Mk III.I was up at Jabara Airport in Wichita today and got to talking with the pilot of a Piaggio Avanti II turboprop. On the way home I got to thinking that If changing the thrust line doesn't work I'm going to make a composite canard and fasten it to the end of the fuselage truss. By my calculations about an 8' span should give just the required lift. Ken will have the first three lifting surface control Kolb.


Rick�

On Tue, Jun 7, 2011 at 1:27 PM, <NeilsenRM(at)gmail.com (NeilsenRM(at)gmail.com)> wrote:
Quote:
Rick/All

I had a long discussion with Brian M at Sun-N-Fun before the tornado hit. He said that the early xtras had a larger horizontal stabilizer to compensate for what they later found was down pressure on the nose from flying nose low. Reducing the wing incidence fixed the problems and increased speeds.

Now for the downward pitching problem I will suggest one more time that you get that trim system working properly. You may need to add a spring or change to a heaver one. Just keep playing with it till it flies level. Flying solo you should be near the low end of pitch trim adjustment so that you will have plenty more trim when you have a heavy passenger. Go ahead and play with the thrust angle but that, according to John H, it will have little impact. For best performance set the thrust angle to level in level flight.

I set my trim for hands off for cruise. I fine tune the trim by adding or reducing power a bit. Kolbs with high thrust engines change the pitch trim it is the nature of the beast. I find that pitch trim at cruise power or low power with one notch of flaps on approach is about the same pitch trim.

Rick Neilsen
Redrive VW Powered MKIIIC


On , Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:

>

Quote:



Rick,



� Sounds like you're on the right path.� Good luck on your next attempt to get it fixed.



� I am curious, before you change the existing thrust line, can you check what the present
>

Quote:
angle is?�� You could probably figure an accurate way to do it, but maybe using a

large rectangle of cardboard, with your protractor taped in place 90 degrees from the

edge you line up with the prop blades.
>

Quote:


� Aslo, can you measure the EXACT height of the�propeller centerline to the boom tube?� I'm

curious how my GEO motor prop centerline measures up against the Rotax 582.
>

Quote:


Mike Welch

out in my shop today painting blue & yellow accent stripes��

high 90's heat and humidity is�rough!!!



>

Quote:


======================

Quote:


Quote:


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--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


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williamtsullivan(at)att.n
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PostPosted: Tue Jun 07, 2011 3:30 pm    Post subject: MkIII Xtra Reply with quote

A Kolb bi-plane!!!

do not archive

--- On Tue, 6/7/11, Richard Girard <aslsa.rng(at)gmail.com> wrote:

Quote:

From: Richard Girard <aslsa.rng(at)gmail.com>
Subject: Re: RE: MkIII Xtra
To: kolb-list(at)matronics.com
Date: Tuesday, June 7, 2011, 5:58 PM

Rick, So far as I can tell, without putting a force gage on the elevator, the trim system is working properly, at least compared to my Mk III. I was up at Jabara Airport in Wichita today and got to talking with the pilot of a Piaggio Avanti II turboprop. On the way home I got to thinking that If changing the thrust line doesn't work I'm going to make a composite canard and fasten it to the end of the fuselage truss. By my calculations about an 8' span should give just the required lift. Ken will have the first three lifting surface control Kolb.


Rick

On Tue, Jun 7, 2011 at 1:27 PM, <NeilsenRM(at)gmail.com (NeilsenRM(at)gmail.com)> wrote:
Quote:
Rick/All

I had a long discussion with Brian M at Sun-N-Fun before the tornado hit. He said that the early xtras had a larger horizontal stabilizer to compensate for what they later found was down pressure on the nose from flying nose low. Reducing the wing incidence fixed the problems and increased speeds.

Now for the downward pitching problem I will suggest one more time that you get that trim system working properly. You may need to add a spring or change to a heaver one. Just keep playing with it till it flies level. Flying solo you should be near the low end of pitch trim adjustment so that you will have plenty more trim when you have a heavy passenger. Go ahead and play with the thrust angle but that, according to John H, it will have little impact. For best performance set the thrust angle to level in level flight.

I set my trim for hands off for cruise. I fine tune the trim by adding or reducing power a bit. Kolbs with high thrust engines change the pitch trim it is the nature of the beast. I find that pitch trim at cruise power or low power with one notch of flaps on approach is about the same pitch trim.

Rick Neilsen
Redrive VW Powered MKIIIC


On , Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
Quote:





Rick,



Sounds like you're on the right path. Good luck on your next attempt to get it fixed.



I am curious, before you change the existing thrust line, can you check what the present

angle is? You could probably figure an accurate way to do it, but maybe using a

large rectangle of cardboard, with your protractor taped in place 90 degrees from the

edge you line up with the prop blades.



Aslo, can you measure the EXACT height of the propeller centerline to the boom tube? I'm

curious how my GEO motor prop centerline measures up against the Rotax 582.



Mike Welch

out in my shop today painting blue & yellow accent stripes

high 90's heat and humidity is rough!!!






======================

Quote:


Quote:


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--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM


It isn't necessary to have relatives in Kansas City in order to be unhappy.
� - Groucho Marx


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