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Tim Juhl
Joined: 21 Mar 2006 Posts: 488 Location: "Thumb" of Michigan
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Posted: Mon Jun 14, 2010 8:45 pm Post subject: Aileron bellcrank wear? |
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This question is for those who've opened their wings up for modification after putting some flight hours on their aircraft.
Has anyone noticed any wear in the holes where the control cables attach to the aileron bellcrank? Since there is tension on the cables I wonder whether the hole is elongating in the direction of the tension being applied. If so, it would seem to me that this would be a good place to install a bushing.
I own a taildragger and one of the things you watch for is that the holes on the rudder horn where the tailwheel springs attach will often wear in such a manner. The rudder horn is half-inch thick aluminum with steel springs attached - much beefier than the bellcrank. The springs are under tension, just like the control cables and over time the steel cuts into the softer aluminum.
Comments?
Tim
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_________________ ______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring! |
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Louie928
Joined: 15 Nov 2009 Posts: 32 Location: Mosier, OR USA
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Posted: Sun Jun 20, 2010 5:04 pm Post subject: Re: Aileron bellcrank wear? |
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I wondered the same thing when I saw the aileron bellcrank. I made different ones using a ball bearing for the pivot bearing and bronze bushings for the cable clevis attachments. The bearing and bushings are from Aircraft Spruce. The new bellcrank is a bit lighter than the original. The thickness is the same so the original attachments can be used with the holes drilled to fit the ball bearing ID.
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_________________ Louis W. Ott
601XL-B Corvair |
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mtherr(at)yahoo.com Guest
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Posted: Sun Jun 20, 2010 5:44 pm Post subject: Aileron bellcrank wear? |
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I cannot say for the aileron bearing. However, it is certainly true for the upper rudder bearing on the HD model. I made a new part after three years of flying. After removing the part, however, I did feel that the part was still safe (plenty of edge distance and no noticeable fluttering or vibration in flight).
----------------------------
Michel Therrien CH601-HD, C-GZGQ
http://mthobby.pcperfect.com/ch601
http://pages.infinit.net/mthobby
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Terry Phillips
Joined: 11 Jan 2006 Posts: 346 Location: Corvallis, MT
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Posted: Sun Jun 20, 2010 8:02 pm Post subject: Aileron bellcrank wear? |
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Louie
You are a true craftsman. You new bellcrank is a work of art. Do you have a
drawing of your design? It looks like a very good design improvement.
I'm thinking that I will replace the nylon fairleads for the aileron
control cables with pulleys. My hope is to reduce the drag in the aileron
control system, and thereby improve the control harmony. This would not be
a possibility without aileron counterbalance, but with the counterbalance,
it should not present a problem. I'm wondering if anyone else has put in
pulleys?
Terry
At 06:04 PM 6/20/2010 -0700, you wrote:
Quote: | I wondered the same thing when I saw the aileron bellcrank. I made
different ones using a ball bearing for the pivot bearing and bronze
bushings for the cable clevis attachments. The bearing and bushings are
from Aircraft Spruce. The new bellcrank is a bit lighter than the
original. The thickness is the same so the original attachments can be
used with the holes drilled to fit the ball bearing ID.
--------
Louis W. Ott
601XL beginner Quick Build
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Terry Phillips
ttp44~at~rkymtn.net
Corvallis MT
ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done;
Upgrading wings & ailerons per the AMD Safety Directive
http://www.mykitlog.com/N47TP/
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_________________ Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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psm(at)att.net Guest
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Posted: Sun Jun 20, 2010 8:40 pm Post subject: Aileron bellcrank wear? |
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Hi Terry,
Before you invest a lot of time and money in changing fairleads to pulleys,
I think you should consider another aspect of the "Control Harmony" issue.
The Zodiac XL has HUGE ailerons. This means force applied to the control
stick doesn't require much movement of the ailerons to produce roll torque.
It also means the ailerons work quite well all the down to stall speed where
most spam cans lose nearly all control effect. I believe it is the geometry
and size of the ailerons that makes them feel so stiff in flight rather than
any drag in the control cables.
Good luck,
Paul
XL fighting main spar rivet removal for the upgrade.
--
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Louie928
Joined: 15 Nov 2009 Posts: 32 Location: Mosier, OR USA
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Posted: Sun Jun 20, 2010 10:35 pm Post subject: Re: Aileron bellcrank wear? |
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Hi Terry,
I do have a drawing I made just to see if it would work. I Printed out a full size example and cut it out from cardboard. I can't remember if any slight changes were done when I cut it from aluminum. I don't think so. The drawing was done in Solidworks. I exported a .jpg file of the drawing so the quality isn't so great. The bronze bushings are Aircraft Spruce P/N FF303-01. Look under Hardware, Bushings. They are $0.19 each. Drill the bushing hole in the bellcrank slightly undersize and press in the bushing. The bellcrank bearing is Aircraft Spruce P/N BC4W10 (AN218-4). Look under Airframe parts, Bearings. It costs $18.95. This bellcrank doesn't require any changes to the normal mount and the geometry is the same as the Zenith bellcrank. Use a washer on top and bottom of the bearing to insure the bearing housing doesn't rub on the support when you tighten the bolt.
I don't know how much drag the fairleads would add to the aileron movement. The cables don't move very far to give full travel. It'll be something I'll check when I connect the controls.
BTW, the SS rivets work great. Thanks
Louie
Terry Phillips wrote: | Louie
You are a true craftsman. You new bellcrank is a work of art. Do you have a
drawing of your design? It looks like a very good design improvement.
I'm thinking that I will replace the nylon fairleads for the aileron
control cables with pulleys. My hope is to reduce the drag in the aileron
control system, and thereby improve the control harmony. This would not be
a possibility without aileron counterbalance, but with the counterbalance,
it should not present a problem. I'm wondering if anyone else has put in
pulleys?
Terry
At 06:04 PM 6/20/2010 -0700, you wrote:
Quote: | I wondered the same thing when I saw the aileron bellcrank. I made
different ones using a ball bearing for the pivot bearing and bronze
bushings for the cable clevis attachments. The bearing and bushings are
from Aircraft Spruce. The new bellcrank is a bit lighter than the
original. The thickness is the same so the original attachments can be
used with the holes drilled to fit the ball bearing ID.
--------
Louis W. Ott
601XL beginner Quick Build
|
Terry Phillips
ttp44~at~rkymtn.net
Corvallis MT
ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done;
Upgrading wings & ailerons per the AMD Safety Directive
http://www.mykitlog.com/N47TP/ |
| - The Matronics Zenith601-List Email Forum - | | 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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_________________ Louis W. Ott
601XL-B Corvair |
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Terry Phillips
Joined: 11 Jan 2006 Posts: 346 Location: Corvallis, MT
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Posted: Fri Jun 25, 2010 3:02 pm Post subject: Aileron bellcrank wear? |
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Hi Paul
I do not have personal experience on the 601XL control harmony problem. My
total time in 601XL is a 30 minute flight in the factory demo plane.
I am just reacting to various posts on line that suggest that control
harmony is not good on the 601XL. I think that it is likely that high
friction in the aileron controls were an important factor in the
pre-upgrade design to avoid aileron flutter. Normal design practice is to
eliminate flutter with counterbalanced control surfaces. (If you look at
almost any certificated airplanes with aluminum skinned ailerons, you will
find counterbalances.) If one can count on the aileron counterbalances to
eliminate flutter in the 601XL, then one should be able to replace the
aileron fairleads with pulleys w/o introducing a new risk of aileron
flutter. Since the elevator and rudder are not counterbalanced, I would not
consider replacing the fairleads in those control links.
If you are correct that the high forces for roll control reported for the
601XL are simply due to the geometry and size of the ailerons, then
installing pulleys will not improve the control harmony. However, if
friction in the control links proves to be significant then pulleys might
make a useful difference. I'm a long way from building my fuselage, so my
ultimate decision on this item is not imminent. Some other builders have
replaced the control cables with push-pull rods. I'm very curious if any
one has replaced the aileron fairleads with pulleys.
Terry
At 09:39 PM 6/20/2010 -0700, you wrote:
Quote: | Hi Terry,
Before you invest a lot of time and money in changing fairleads to pulleys,
I think you should consider another aspect of the "Control Harmony" issue.
The Zodiac XL has HUGE ailerons. This means force applied to the control
stick doesn't require much movement of the ailerons to produce roll torque.
It also means the ailerons work quite well all the down to stall speed where
most spam cans lose nearly all control effect. I believe it is the geometry
and size of the ailerons that makes them feel so stiff in flight rather than
any drag in the control cables.
Good luck,
Paul
|
Terry Phillips
ttp44~at~rkymtn.net
Corvallis MT
ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done;
Upgrading wings & ailerons per the AMD Safety Directive
http://www.mykitlog.com/N47TP/
| - The Matronics Zenith601-List Email Forum - | | 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:
http://www.matronics.com/Navigator?Zenith601-List |
|
_________________ Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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Terry Phillips
Joined: 11 Jan 2006 Posts: 346 Location: Corvallis, MT
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Posted: Sat Jun 26, 2010 10:17 am Post subject: Aileron bellcrank wear? |
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Hi Louie
Thank you for the details.
Have you tried exporting the drawing to a .png? I find that png's do not
have the noise that creeps into jpg's at the sharp, black-white boundaries
in drawings and text. If you could email me a copy of your image, I'd
appreciate it. Another alternative to jpg's is a pdf. The Windows freebie
pdf creator from SourceForge is invaluable to me. I'm sure that there are
Linux equivalents.
'Glad to hear that the SS rivets are proving useful. I used a bunch of them
on my garage door and they have been perfect. If and when I get the invoice
from Lehigh-Armstrong, I'll work out the cost split and let you know. I
called L-H Friday, but it was late and I just got their voice mail.
Thanks for the great idea on improving the aileron bellcrank.
Terry
At 11:35 PM 6/20/2010 -0700, you wrote:
Quote: | Hi Terry,
I do have a drawing I made just to see if it would work. I Printed out a
full size example and cut it out from cardboard. I can't remember if any
slight changes were done when I cut it from aluminum. I don't think so.
The drawing was done in Solidworks. I exported a .jpg file of the drawing
so the quality isn't so great. The bronze bushings are Aircraft Spruce P/N
FF303-01. Look under Hardware, Bushings. They are $0.19 each. Drill the
bushing hole in the bellcrank slightly undersize and press in the bushing.
The bellcrank bearing is Aircraft Spruce P/N BC4W10 (AN218-4). Look under
Airframe parts, Bearings. It costs $18.95. This bellcrank doesn't require
any changes to the normal mount and the geometry is the same as the Zenith
bellcrank. Use a washer on top and bottom of the bearing to insure the
bearing housing doesn't rub on the support when you tighten the bolt.
I don't know how much drag the fairleads would add to the aileron
movement. The cables don't move very far to give full travel. It'll be
something I'll check when I connect the controls.
BTW, the SS rivets work great. Thanks
Louie
|
Terry Phillips
ttp44~at~rkymtn.net
Corvallis MT
ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done;
Upgrading wings & ailerons per the AMD Safety Directive
http://www.mykitlog.com/N47TP/
| - The Matronics Zenith601-List Email Forum - | | 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:
http://www.matronics.com/Navigator?Zenith601-List |
|
_________________ Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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