Today's Message Index:
----------------------
0. 12:17 AM - Fund Raiser Lagging Last Year By Over 30%... (Matt Dralle)
1. 07:11 AM - Re: Zenith-List Digest: 41 Msgs - 11/12/08 (mversteeg)
2. 07:24 AM - Re: Heavy engine and Horiz. stab (Sabrina)
3. 08:34 AM - Re: Heavy engine and Horiz. stab (Bryan Martin)
4. 08:57 AM - Re: Re: Zenith-List Digest: 41 Msgs - 11/12/08 (Paul Mulwitz)
5. 11:54 AM - Mean Aerodynamic Chord (George Swinford)
6. 12:23 PM - Re: Mean Aerodynamic Chord (steve)
7. 01:21 PM - Re: Re: Cable Tensions for 601XL? (JAPhillipsGA@aol.com)
8. 06:27 PM - Re: 601XL Wing Flutter (David X)
9. 07:04 PM - Re: Re: 601XL Wing Flutter (steve)
10. 08:30 PM - 601XL - Aileron Trim Tab Deflection (Dave VanLanen)
11. 09:39 PM - Re: 601XL - Aileron Trim Tab Deflection (Ron Lendon)
12. 10:47 PM - I've moved to FLAG (and you can too) (Richard Vetterli)
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| Subject: | Fund Raiser Lagging Last Year By Over 30%... |
As of the 13th, the Fund Raiser is currently about 30% behind last year in terms
of the number of Contributions. Yet, oddly the number of messages posted per
day is up by 10 to 20% on the average. It costs real money to run these Lists
and they are supported 100% though your Contributions during the Fund Raiser.
Won't you please take a minute right now to make your Contribution to keep
these Lists up and running?
Contribution Page:
http://www.matronics.com/contribution
Thank you for your support!
Matt Dralle
Email List Admin.
Message 1
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| Subject: | Re: Zenith-List Digest: 41 Msgs - 11/12/08 |
Hello Paul,
I agree, and although complex panels seem to attract some, I like the clean
panels. I also know that experimental - amateur built airplanes don't fall
under all the rules. But on the other hand I have heard stories where
the DAR
sometimes is very specific (remember the whiskey compass discussion).
I hope you will have a DAR that accepts this and sees the sense of you
argument.
Regards,
Maarten,
plans building XL, getting close to closing the second wing
> Time: 08:03:02 AM PST US
> From: Paul Mulwitz <psm@att.net>
> Subject: Re: Zenith-List: Wires and fuses and such
>
>
> Hi Maarten,
>
> I guess the regulation you cited explains why so many panels are
> crowded with circuit breakers. In their great wisdom, the FAA seems
> to have dictated that solution.
>
> Fortunately, I don't think part 23 regulations apply to experimental
> - amateur built airplanes. This may be one of many examples of the
> notion that the FAA regulations are overly restrictive on certified planes.
>
> To directly answer your question, my plans are to limit my flights to
> Day/VFR. I suspect I could safely conduct such flights without any
> electrical equipment operating at all. The only really essential
> piece of electrical gear is the starter motor. My Jabiru is not
> likely to start any other way.
>
> Best regards,
>
> Paul
Message 2
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| Subject: | Re: Heavy engine and Horiz. stab |
Grant,
You have an HDS. Bryan, Scott and I used XL plans or kit. From my comparison
of the HDS vs. XL, the XL decreased the decalage. Then the 650 increased the
decalage. All Bryan, Scott and I did was increase the decalage of our aircraft
to a range similar to that built into your HDS and the new 650s. The factory
shifts the wing, we shift the H stab.
Other than an HD series used for aerobatics, I don't know of a single 600 series
with the increased (I would call nominal) decalage that has had a structural
failure. We have had this argument before, but it was prior to the increase
in the 650's decalage.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=214193#214193
Message 3
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| Subject: | Re: Heavy engine and Horiz. stab |
I agree with you on all counts but, the airplane also has to be built
with the proper decalage between the wing and stabilizer. In my case,
the CG was within the acceptable range and I still could not trim it
out. With the CG near the aft limit I was just able to trim it with
full tab deflection. With my aerospace engineering education, I
determined that the solution to this situation was to re-pitch the
stabilizer. I had somehow got the decalage slightly off during
construction. It worked and my test flights after the correction
showed the airplane had adequate pitch stability.
If we were all building our airplanes in identical rigging fixtures
they would all be rigged the same. Since each one is hand built by a
different individual, you can expect slight differences in the final
product. It should be no surprise that the need for some small
corrections might be found during the phase 1 testing.
On Nov 13, 2008, at 9:05 PM, Frank Roskind wrote:
> A heavy engine does not require more down force on the elevator if
> the plane is balanced correctly.. A properly balanced standard
> configuration airplane needs a center of mass ahead of the center of
> lift, which would produce a nose down pitching force if there were
> no force applied from the horizontal stabilizer and elevator. The
> Horizontal empennage surfaces provide a downward force in order to
> keep rotational forces in balance. When that force is diminished
> the nose pitches downward, which is what happens to a stable
> airplane in a stall. The center of mass should always be in a range
> relataive to the datum which keeps the Center of Mass in front of
> the center of lift by a small margin. Too great a margin will mean
> that the plane will be difficult to fly and may not even rotate for
> takeoff. Further, the stall speed is raised as the Center of Mass
> moves forward, because the lifting surface must offset the downward
> force at the tail.
>
> You need to build your airplane so the Center of Mass is within the
> designer's specs. You can do that by moving the engine closer to
> the firewall, if possible, or by putting wieghts in the rear of the
> aircraft. It is better that the weight come from equipment, but the
> weight could also come from mere ballast. If you move your engine
> back, you may need to add some kind of spacer for the propeller for
> better handling and performance.
>
> In my opinion it would be dangerous for a non-expert simply to make
> the tail surfaces larger, or to pitch them at a steeper downward
> angle, to offset the weight of an engine. If you intend to do
> something like that please consult with Zenith first, for your own
> safety.
>
--
Bryan Martin
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive.
Message 4
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| Subject: | Re: Zenith-List Digest: 41 Msgs - 11/12/08 |
Hi Maarten,
I don't want to get into a regulation interpretation battle, but I
will if I must.
As I understand the regs and DAR history, the compass issue is
completely separate from the part 23 question. Part 23 clearly
doesn't apply to Experimental airplanes. Experimental airplanes do
require a compass. The issue I have heard discussed is whether the
compass must be a whiskey compass or if one of the new-fangled
electrical devices like the one found on the Dynon EFIS is sufficient
to meet this need.
I think the electrical compass is really satisfactory to meet the
requirements, but some builders have run into this issue with their
DAR and decided a cheap automotive whiskey compass was an easy way to
get past an old fashioned DAR.
From a strictly practical point of view, it makes sense that you
need to be able to figure what direction you are going under all
circumstances - including electrical failure. The same argument
doesn't apply to trying to trouble-shoot electrical problems while
still in flight.
Best regards,
Paul
XL getting close
At 07:10 AM 11/14/2008, you wrote:
>Hello Paul,
>
>I agree, and although complex panels seem to attract some, I like the clean
>panels. I also know that experimental - amateur built airplanes don't fall
>under all the rules. But on the other hand I have heard stories where the DAR
>sometimes is very specific (remember the whiskey compass discussion).
>I hope you will have a DAR that accepts this and sees the sense of you
>argument.
>
>Regards,
> Maarten,
> plans building XL, getting close to closing the second wing
Message 5
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| Subject: | Mean Aerodynamic Chord |
John Read, and others:
"Mean Aerodynamic Chord" is a length, rather than a point. For an
untapered wing, the MAC is the length of the chord measured anywhere
along the span. For a tapered planform the MAC is found at a spanwise
location where the chord is sort of an average of all the chord lengths.
On a wing with simple taper this is easily determined. For a planform
with sweep and multiple tapers, typical of modern airliners, it becomes
a bit more complicated.
I think the point to which you refer is the so-called "aerodynamic
center", which is found on the MAC at a distance equaling approximately
25 percent of the MAC aft of the leading edge. The acceptable range of
center of gravity locations is usually expressed in percent of MAC; for
a particular airplane it might be from 10 percent to 30 percent. The
acceptable CG range depends on a number of design features, one of the
most powerful being the tendency of the wing to pitch or rotate about
its spanwise axis. This tendency must be counteracted by other forces
on the airplane, largely by a down force generated by the horizontal
tail.
The popular old NACA 23000 series airfoils (23012, 23015 etc) were
designed to have a low pitching moment. Symmetrical airfoil sections
(for example 23000) have zero pitching moment and have often been used
on helicopter blades and aerobatic airplanes for that reason.
Incidentally, "symmetrical" means identical, top and bottom. Some refer
to an airfoil as symmetrical just because it has some curvature on the
lower surface, but this is incorrect.
You are correct in noting that flying wings typically use an airfoil
section which has a reflexed trailing edge. This reduces the pitching
tendency to near zero and deflection of the trailing edge surfaces does
the rest. You are also correct in noting that changing the incidence of
the stabilizer is not the way to correct a static balance situation,
although it will have an effect on the overall static stability.
I hope this helps generate light, rather than heat.
George
Message 6
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| Subject: | Re: Mean Aerodynamic Chord |
Right On !
----- Original Message -----
From: George Swinford
To: zenith-list@matronics.com
Sent: Friday, November 14, 2008 12:52 PM
Subject: Zenith-List: Mean Aerodynamic Chord
John Read, and others:
"Mean Aerodynamic Chord" is a length, rather than a point. For an
untapered wing, the MAC is the length of the chord measured anywhere
along the span. For a tapered planform the MAC is found at a spanwise
location where the chord is sort of an average of all the chord lengths.
On a wing with simple taper this is easily determined. For a planform
with sweep and multiple tapers, typical of modern airliners, it becomes
a bit more complicated.
I think the point to which you refer is the so-called "aerodynamic
center", which is found on the MAC at a distance equaling approximately
25 percent of the MAC aft of the leading edge. The acceptable range of
center of gravity locations is usually expressed in percent of MAC; for
a particular airplane it might be from 10 percent to 30 percent. The
acceptable CG range depends on a number of design features, one of the
most powerful being the tendency of the wing to pitch or rotate about
its spanwise axis. This tendency must be counteracted by other forces
on the airplane, largely by a down force generated by the horizontal
tail.
The popular old NACA 23000 series airfoils (23012, 23015 etc) were
designed to have a low pitching moment. Symmetrical airfoil sections
(for example 23000) have zero pitching moment and have often been used
on helicopter blades and aerobatic airplanes for that reason.
Incidentally, "symmetrical" means identical, top and bottom. Some refer
to an airfoil as symmetrical just because it has some curvature on the
lower surface, but this is incorrect.
You are correct in noting that flying wings typically use an airfoil
section which has a reflexed trailing edge. This reduces the pitching
tendency to near zero and deflection of the trailing edge surfaces does
the rest. You are also correct in noting that changing the incidence of
the stabilizer is not the way to correct a static balance situation,
although it will have an effect on the overall static stability.
I hope this helps generate light, rather than heat.
George
Message 7
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| Subject: | Re: Cable Tensions for 601XL? |
Jay, thanks for the info. I finished my XL over three years ago and built
the tail feathers back in '03 so I don't remember this. I need to check my
plans and look to see if I did this mod. Thanks, Bill of Georgia
do not archive
**************Get the Moviefone Toolbar. Showtimes, theaters, movie news &
p://toolbar.aol.com/moviefone/download.html?ncid=emlcntusdown00000001)
Message 8
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| Subject: | Re: 601XL Wing Flutter |
I wonder if you have verified the cable tensions for your ailerons. This seems
to be a focus of concern with the NTSB regarding at least one recent 601XL crash.
--------
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=214298#214298
Message 9
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| Subject: | Re: 601XL Wing Flutter |
Bill, isnt 140 a little fast for the 601 ? especiall in rough air..
Also read the CFRs about flying near power stations.....
----- Original Message -----
From: "David X" <dxj@comcast.net>
Sent: Friday, November 14, 2008 7:26 PM
Subject: Zenith-List: Re: 601XL Wing Flutter
>
> I wonder if you have verified the cable tensions for your ailerons. This
> seems to be a focus of concern with the NTSB regarding at least one recent
> 601XL crash.
>
> --------
> Zodiac 601 XL - CZAW Built - Rotax 912S
> DO NOT ARCHIVE
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=214298#214298
>
>
>
Message 10
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| Subject: | 601XL - Aileron Trim Tab Deflection |
I just finished installing my aileron trim, and when I tested it, I can only
get a total of 40 degrees of deflection. According to the plans, I should
be able to get 50 degrees of deflection (25 up and 25 down). Adjusting the
length of the control rod only changes the distribution of the 40 degrees
between up and down - it does not increase the total deflection. I checked
that the servo was working correctly, which it was (.7" travel per specs).
I also checked that there was no binding of the control rod clevis with the
trim tab horn angle. The only thing I could find was that the center of the
control rod mounting hole in the horn angle was 13 mm up from the flange
instead of the 12 mm specified in the plans. I find it hard to believe that
1 mm would cause a 10 degree loss in deflection.
Has anyone else experienced this problem, and if so, what did you do to
resolve?
Thanks,
Dave Van Lanen
601XL - tail done, flaps done, working on ailerons
Message 11
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| Subject: | Re: 601XL - Aileron Trim Tab Deflection |
Looks like the difference between 12mm and 13mm would be about 1.7 degrees at the
.7 travel. I didn't calculate what it would be out at the tip of the trim
tab, don't have the dimension handy.
--------
Ron Lendon, Clinton Township, MI
Corvair with Roy's Garage 5th bearing
Zodiac XL, ScrapBuilder ;-)
http://www.mykitlog.com/rlendon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=214324#214324
Message 12
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| Subject: | I've moved to FLAG (and you can too) |
Attention Northern California (SF Bay Area) builders.
After building in my garage for the past four years,
I've moved my project to "First Light Aviation Group"
(FLAG) in Livermore, California, adjacent to the
Livermore Airport (lvk). FLAG has individual building
bays, each one complete with plenty of power,
compressed air, large locking tool boxs, work tables,
shelves and a pallet rack for large parts. FLAG also
supplies large tools (drill press, shear, brake, etc)
with convenient bathrooms, vending machines, fridge
and microwave. And, it's available 24/7. In the
lobby is a retail store with pilot supplies and
building supplies. A large meeting room upstairs
rounds out the facility. I found that when I moved my
airplane to FLAG, I was able to work in the company of
fellow builders/pilots and without the distractions of
building at home. Now I'm confident that I'll get my
plane flying in short order. No one asked me to post
this and I'm not affiliated with FLAG, I'm just a
happy customer. Check it out at www.flaglvk.com
Rich Vetterli
601XL/Corvair
95% done, 95% to go
Check out my progress at www.geocities.com/stixx5a
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