Today's Message Index:
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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
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Subject: | Re: : Kolb-List:Stabilizer Angle |
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
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Subject: | Re: 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
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Subject: | Re: 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
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Subject: | Re: : Kolb-List:Stabilizer Angle |
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
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Subject: | Re: : Kolb-List:Stabilizer Angle |
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
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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
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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
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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
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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
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Subject: | Re: : Kolb-List:Stabilizer Angle |
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.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=482402#482402
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