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Kolb detail photos (now rudder cables)

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stuart(at)harnerfarm.net
Guest

Posted: Thu Jan 23, 2014 7:27 am Post subject: Kolb detail photos (now rudder cables)

Your clearance problem is exactly the way my firefly is.  Only a problem at

full up elevator.  Also caused by the compression sleeves, not the cable

itself.



At this point I don't see what can be done to change the design enough to

make it work better, but it needs to have something done to it.



Since the problem is the compression sleeves, and mostly the second one in

from the end, maybe a making a new cable with the second sleeve either moved

forward another 1/2"  or positioned right up next to the first sleeve.

Either way, it would mean making all new cables which is something I am not

prepared to do just yet.  Had I known about this before I made the cables, I

might have tried something else.



After looking at some other airplane cables I am not convinced that a double

sleeve is needed (I need to look in AC 43 to see what it says about the

subject), however I am not willing to go with just one sleeve on the rudder

cables without a pretty compelling reason.



When compressing the sleeves, a small ridge rolls up right at the outer

edges, at least with my compression tool anyway.  What I plan on doing when

I take the tail feathers off for covering is to lightly file those sharp

ridges down a little so they do not dig into the elevator horn as much.



A small piece of heat shrink tubing on the cable will help ramp the cables

over the elevator horn when they make contact and will soften the contact.

There are downsides to this as it will not last forever and it will possibly

trap moisture and then hide it from inspection.  So, one may be making a

more dangerous situation, as you can easily watch and touchup the elevator

horn when needed.  I wonder if you can buy clear heat shrink tubing?



I have some heat shrink tape that is not very useful for electrical work,

but I may try to put some on the elevator horn.  It can be replaced as

needed.



As a perfectionist, the other thing that bothers me is all the cables just

lay on the bottom of the tail boom, rubbing both the boom and the other

cables.  In a perfect world they would all be riding on pulleys and not

touching anything else.  To do this, even if I could figure out how, would

add quite a lot of complexity and some weight.  Some have suggested perhaps

working a very thin sheet of some tough plastic material into the boom and

then a few rivets to hold it down.  Again, hard to do and traps moisture.



Realistically, how many times do you have to move those cables to actually

cause any damage, and how many flight hours would that be?  When I stop and

think about it, that perfectionist side of me needs to be tamed down a

little. 



Stuart



 



--

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Jan 23, 2014 7:45 am Post subject: Kolb detail photos (now rudder cables)

Kolbers:



There are a lot of Kolbs out there, all models, with clanging cables

smacking the tail boom when taxiing, rubbing against each other, etc.  I do

not know of any that have failed for any reason in the last 30 years that I

have been building and flying Kolbs.  My MKIII has over 3,200.0 hours on the

airframe, has all the symptoms of clanging cables, and is still safe and

flying strong.



My MKIII also had the problem of nicopress sleeve hitting rudder horn.  I

filed the ridge off the offender when I built it in 1991.  I don't cover up

nicopress sleeves.  I want to be able to see them.



If something bothers you, fix it, and remember how many of these Kolbs are

out there flying and how long they have been flying.



john h

mkIII

Titus, Alabama         Airframe:  3,229.5 hours     Engine:  611.0 hours



--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Ducati SS

Joined: 15 Oct 2009
Posts: 93

Posted: Thu Jan 23, 2014 9:08 am Post subject: Re: Kolb detail photos (now rudder cables)

Yes you can buy clear heat shrink , I have some. Of course it needs to go on the cable prior to pressing. Another possible solution I have considered is to remove the bell crank, fabricate a curved support saddle for the bottom half of the tube and using my shop press, press a small flat relief at the sleeve contact site. I am considering going experimental with the plane and though I see no safety issue I wonder if the FAA  may have a problem with the interference.

koxxy

Joined: 19 Oct 2011
Posts: 28
Location: Beaverton, OR

Posted: Thu Jan 23, 2014 11:38 am Post subject: Kolb detail photos (now rudder cables)

I am building an Earthstar eGull, just lurking here. Mark Beierle solved the "chafing cable" issue by placing a "comb" on the forward face of the boom, UHMW or teflon, 1/8" thick, with slits where the cables are supposed to be. Simple, light weight, and should last a while (unless your angle change is large).

 



On Thu, Jan 23, 2014 at 7:26 AM, Stuart Harner <stuart(at)harnerfarm.net (stuart(at)harnerfarm.net)> wrote:

 [quote]--> Kolb-List message posted by: "Stuart Harner" <stuart(at)harnerfarm.net (stuart(at)harnerfarm.net)>

  

 Your clearance problem is exactly the way my firefly is.  Only a problem at

 full up elevator.  Also caused by the compression sleeves, not the cable

 itself.

 

 At this point I don't see what can be done to change the design enough to

 make it work better, but it needs to have something done to it.

 

 Since the problem is the compression sleeves, and mostly the second one in

 from the end, maybe a making a new cable with the second sleeve either moved

 forward another 1/2"  or positioned right up next to the first sleeve.

 Either way, it would mean making all new cables which is something I am not

 prepared to do just yet.  Had I known about this before I made the cables, I

 might have tried something else.

 

 After looking at some other airplane cables I am not convinced that a double

 sleeve is needed (I need to look in AC 43 to see what it says about the

 subject), however I am not willing to go with just one sleeve on the rudder

 cables without a pretty compelling reason.

 

 When compressing the sleeves, a small ridge rolls up right at the outer

 edges, at least with my compression tool anyway.  What I plan on doing when

 I take the tail feathers off for covering is to lightly file those sharp

 ridges down a little so they do not dig into the elevator horn as much.

 

 A small piece of heat shrink tubing on the cable will help ramp the cables

 over the elevator horn when they make contact and will soften the contact.

 There are downsides to this as it will not last forever and it will possibly

 trap moisture and then hide it from inspection.  So, one may be making a

 more dangerous situation, as you can easily watch and touchup the elevator

 horn when needed.  I wonder if you can buy clear heat shrink tubing?

 

 I have some heat shrink tape that is not very useful for electrical work,

 but I may try to put some on the elevator horn.  It can be replaced as

 needed.

 

 As a perfectionist, the other thing that bothers me is all the cables just

 lay on the bottom of the tail boom, rubbing both the boom and the other

 cables.  In a perfect world they would all be riding on pulleys and not

 touching anything else.  To do this, even if I could figure out how, would

 add quite a lot of complexity and some weight.  Some have suggested perhaps

 working a very thin sheet of some tough plastic material into the boom and

 then a few rivets to hold it down.  Again, hard to do and traps moisture.

 

 Realistically, how many times do you have to move those cables to actually

 cause any damage, and how many flight hours would that be?  When I stop and

 think about it, that perfectionist side of me needs to be tamed down a

 little. 

 

 Stuart

 

 

 

 --

stuart(at)harnerfarm.net
Guest

Posted: Thu Jan 23, 2014 11:58 am Post subject: Kolb detail photos (now rudder cables)

Thanks John, that is the kind of feedback I need to keep from going

overboard. 



Having never been around a Kolb of any version before, my only point of

reference is the certified stuff I used to fly, and I know that even there,

sometimes perfect is still way beyond safe and reasonable.



I think that there has to be a merging of good enough, craftsmanship and

perfection.  



Stuart



--

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Jan 23, 2014 12:55 pm Post subject: Kolb detail photos (now rudder cables)

Maybe I don't understand the problem you are having.  Did you run out of

space/clearance between the rudder horn and the inside of the tail boom?



Did you speak to Kolb Aircraft Company to see if this was a production

problem or make a onetime screw up?



Everything produced at Kolb is welded in jigs.



john h

mkIII

Titus, Alabama



--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

stuart(at)harnerfarm.net
Guest

Posted: Thu Jan 23, 2014 1:28 pm Post subject: Kolb detail photos (now rudder cables)

Mine is a quick build, so all of those parts were installed by the factory.

All I did was make and install the cables.



If the rudder horn is moved up, then the cables would hit the top of the

tail boom, all of the time.  The only time the cables touch the elevator

horn is when the elevator is at the uppermost deflection.  Still the

nicopress sleeves scrape the paint off of the elevator horn, exposing bare

steel to rusting.



I think I can cure this with a little smoothing of the edges of the sleeves

and a small wear block on the elevator horn.  I have to do some scrounging

but I think a very small piece of pvc pipe that will fit over the horn may

do the trick.  Say an inch long for each cable location.  Split the pipe so

that it can be pried on over the elevator horn.  Maybe a small drop of

silicone to secure it.  Check on it at preflight and remove and replace when

needed.



This idea just popped into my head, I need to go to the shop and see what I

can invent.



Stuart



--

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Jan 23, 2014 1:37 pm Post subject: Kolb detail photos (now rudder cables)

Recommend calling Bryan Melburn 

at Kolb to see what he suggests.



john h

mkIII

Titus, Alabama



--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

jbhart(at)onlyinternet.ne
Guest

Posted: Thu Jan 23, 2014 4:00 pm Post subject: Kolb detail photos (now rudder cables)

At 09:08 AM 1/23/2014 -0800, you wrote:

 	  Quote: 	
		  

........................ I am considering going experimental with the plane 
	


and though I see no safety issue I wonder if the FAA  may have a problem 

with the interference.

 	  Quote: 	
		  




	


Nice looking FireFly. 



If you plan to fly it as an ultralight vehicle (AC 103-7) the FAA has 

nothing to do with checking anything.



The only thing the FAA can do is to ask you to provide proof that your 

ultralight vehicle meets AC 103-7 requirements.



Jack B. Hart FF004

Winchester, IN

Ducati SS

Joined: 15 Oct 2009
Posts: 93

Posted: Fri Jan 24, 2014 4:32 am Post subject: Re: Kolb detail photos (now rudder cables)

My first flights were part 103, but now I am considering a larger fuel tank which would move the plane out of 103.

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