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Bungee best practice questions

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Paul A. Franz, P.E.

Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA

Posted: Fri Jun 24, 2011 6:04 am Post subject: Bungee best practice questions

After cutting the bungee is there something that should be done to protect the cut

ends such as dipping the last 1/4" in epoxy cement? I put two wraps of electrical tape

around the bungee and did the cuts right through the tape.



How many and what type of clamp should be used to hold the two ends together or make a

loop? How do you know if the clamp is tight enough or too tight? I used six wraps of

safety wire with my "clamp tight" tool. Using this tool one could strangle the bungee

to any degree desired. I didn't use any sleeve under the wire strands. Will this be a

problem?



-- 

Paul A. Franz, P.E.

PAF Consulting Engineers

Office 425.440.9505

Cell 425.241.1618

_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Fri Jun 24, 2011 9:13 am Post subject: Re: Bungee best practice questions

 	  Quote: 	
		  How many and what type of clamp should be used to hold the two ends together or make a

loop? How do you know if the clamp is tight enough or too tight? I used six wraps of

safety wire with my "clamp tight" tool. Using this tool one could strangle the bungee

to any degree desired. I didn't use any sleeve under the wire strands. Will this be a

problem? 	




The only official information on making bungee ends I have found is in 43.13-2B in the Ski installation section.  It recommends using using No. 9 cotton or 0.041" (minimum) safety wire.



I made one using round rib lacing cord to wrap the loop.  I tested it putting the loop over a bolt in my bench vise, grabbing the cord with both hands, bracing one foot on the bench, and rocking back with all my weight.  The cord slipped a little under the wrapping.



I tried again but this time clamped the loop tail ends in the vise and stretched the loop out with a come along, then wrapped the lacing cord around it.  This method made the cord much tighter around the loop.  I can't budge it at all.



I still don't trust my home made bungee so I bit the bullet and ordered the factory ones.  



-- 

Paul A. Franz, P.E.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Jul 24, 2011 11:31 am Post subject: Re: Bungee best practice questions

--------------------------------------------------------------------------------

 

Here you go as promised............... 



Cannot be easier to put on Bungees 



http://www.youtube.com/watch?v=c_kEZnXDgYM 



I just plain sick of hearing about all the whining about bungees 



visegrips, clamps bla bla blah !!!! 



Simple Tube gear Bungee install .............

_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Thu Jul 28, 2011 1:00 am Post subject: Re: Bungee best practice questions

 	  dave wrote: 	
		   Cannot be easier to put on Bungees 



http://www.youtube.com/watch?v=c_kEZnXDgYM 	




Hello Dave,

I have known you for many years and I have admired all you have done with your Kitfox and the many videos you have posted on YouTube. You are a real bush pilot!



Looking at this video, I understand that you find replacing the bungees easy ... because you remove your seat!



I haven't built my Kitfox myself, only installed a Jabiru engine, but in my plane, the seat is fastened with a hell of a lot of tiny screws along the two tubes that supports it.



May I ask you how your seat is fastened? Do you unscrew all those screws or do you have a better or easier way to fasten it?



Cheers,

Michel

Kitfox III + Jabiru 2200

_________________
Kitfox 3 - Jabiru 2200

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Fri Jul 29, 2011 5:27 am Post subject: Re: Bungee best practice questions

 	  Quote: 	
		  May I ask you how your seat is fastened? Do you unscrew all those screws or do you have a better or easier way to fasten it? 	




Michel, Dave must be at Oshkosh.  Almost all kitfox seats are attached to the tubing with plastic zip ties.  That is the way it was designed to be.  Yes, better because it is easy to remove the seat to inspect and do maintenance.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

lcfitt(at)sbcglobal.net
Guest

Posted: Fri Jul 29, 2011 6:22 am Post subject: Bungee best practice questions

Michel,



I should comment on this as well.  The original builder of the Outback I 

helped finish had the seats attached with screws placed about every four 

inches.  When installing the seat pan it was a real challenge as every hole 

had to line up for the screws to be inserted.  We found there had to be a 

sequence or it would never work - emphasizing the word "work".  I think I 

might suggest sealing the holes in the tubing and then cutting the slots in 

the seat pan for the Nylon wire ties.  At least in our case, it would save a 

lot of work installing the seat pan.  I routinely removed the seat pan for 

the annual condition inspection.  That would be a good time to check the 

bungees and see if they needed attention.



Lowell



--------------------------------------------------

From: "Tom Jones" <nahsikhs(at)elltel.net>

Sent: Friday, July 29, 2011 6:27 AM

To: <kitfox-list(at)matronics.com>

Subject: Re: Bungee best practice questions



 	  Quote: 	
		   

> May I ask you how your seat is fastened? Do you unscrew all those screws 

> or do you have a better or easier way to fasten it?

 Michel, Dave must be at Oshkosh.  Almost all kitfox seats are attached to 

 the tubing with plastic zip ties.  That is the way it was designed to be. 

 Yes, better because it is easy to remove the seat to inspect and do 

 maintenance.



 --------

 Tom Jones

 Classic IV

 503 Rotax, 72 inch Two blade Warp

 Ellensburg, WA





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=347989#347989

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sat Jul 30, 2011 1:17 am Post subject: Re: Bungee best practice questions

Thank you, Lowell and Tom. This has been a problem for all these years because my Norwegian general ultralight yearly maintenance requires me to remove the seat for inspection. In my report, I write: Seat not removable.



One more question: What is the structural importance of the seat. I mean, if it is not important could I, e.g. fasten it with velcro going all the way along the lower and higher tubes? It sounds even simpler than zip ties. But will it hold?



Cheers,

Michel

_________________
Kitfox 3 - Jabiru 2200

Paul A. Franz, P.E.

Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA

Posted: Sat Jul 30, 2011 2:21 am Post subject: Bungee best practice questions

On Sat, July 30, 2011 2:17 am, Michel wrote:

 	  Quote: 	
		   



 Thank you, Lowell and Tom. This has been a problem for all these years because my

 Norwegian general ultralight yearly maintenance requires me to remove the seat for

 inspection. In my report, I write: Seat not removable.



 One more question: What is the structural importance of the seat. I mean, if it is not

 important could I, e.g. fasten it with velcro going all the way along the lower and

 higher tubes? It sounds even simpler than zip ties. But will it hold?


	


Michel - Velcro only works well when the removal action allows you to peel it, so at

least one side must be on a flexible surface otherwise you have to separate the two

parts all at once and that doesn't work well. It tends to destroy the Velcro's

attachment to the rigid parts. Velcro would be suitable, for example to maintain the

position of a cushion on the seat but not the hard seat to the tubing.



My Merlin has a split bench seat arrangement and I used plastic zip ties to hold the

three parts in place. In my case, I don't anticipate ever having to remove it as it

hides nothing that you can't easily reach. I did remove it to apply another coat of

finish to the wood pieces and reattaching using the original holes went quickly. The

second time I was very careful about where the sharp trimmed ends would wind up so

reaching under the base doesn't result in cut in my wrist. I use Velcro to keep the

cushions in place which is nice for easy removal when cleaning is required.



-- 

Paul A. Franz, P.E.

PAF Consulting Engineers

Office 425.440.9505

Cell 425.241.1618

_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sat Jul 30, 2011 8:19 am Post subject: Bungee best practice questions

Michel-

The seat in my plane is attached with 4 hose clamps. The clamps are  

fitted through slots cut into the seat material, and go around the  

tubing. Earlier on, there was a kit sold that used web straps that  

were glued onto the bottom of the seat for structural support, and  

then the seat was attached with 8 hose clamps. I used the 8 clamps,  

but soon felt that 4 was sufficient, and that is what I use. Far  

better than the plastic straps, from a mental point of view.  : )



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Prince prop 64 x 30, P-tip

Electroair direct-fire ignition system

Rotec TBI-40 injection (sleeved to 36mm)

Status: flying with "Ramcharger" intake manifold...1151 hrs (since  

3-27-2006)



On Jul 30, 2011, at 5:17 AM, Michel wrote:



 	  Quote: 	
		   



 Thank you, Lowell and Tom. This has been a problem for all these  

 years because my Norwegian general ultralight yearly maintenance  

 requires me to remove the seat for inspection. In my report, I  

 write: Seat not removable.



 One more question: What is the structural importance of the seat. I  

 mean, if it is not important could I, e.g. fasten it with velcro  

 going all the way along the lower and higher tubes? It sounds even  

 simpler than zip ties. But will it hold?



 Cheers,

 Michel



 --------

 Kitfox 3 - Jabiru 2200





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=348058#348058

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sat Jul 30, 2011 11:20 pm Post subject: Re: Bungee best practice questions

Thanks, Paul and Lynn. Indeed, velcro needs something that can bend to peel it off. Hose clamps seem a good idea too, Lynn. What I wanted to make sure is that there is no structural weakness induced by making a simpler attachment than those multitude of tiny screws I have.

I thought about velcro, Paul, because the guy who built my Kitfox in 1992 was very fond of it and used it extensively to attach the seat covers, etc.



Thanks again, guys!

Cheers,



Michel

_________________
Kitfox 3 - Jabiru 2200

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Mon Aug 01, 2011 4:08 pm Post subject: Re: Bungee best practice questions

Michel,

Hose clamps best way to go --  I do not like any holes in 4130 tube that cold allow moisture into.   I will have to post some pics.   I alos have done a few kitfox with wood block laminated to the bottom of the fiber glass seat that rest on the 1/2" 4130 tube under the seat. This way it a deadman's block to ensure that no way your seat can jam your  2 control tube that pass under the seat. 

Glad you enjoy the videos -- no I was not at OSH but at cottage. 



 



 	  Michel wrote: 	
		   	  dave wrote: 	
		   Cannot be easier to put on Bungees 



http://www.youtube.com/watch?v=c_kEZnXDgYM 	




Hello Dave,

I have known you for many years and I have admired all you have done with your Kitfox and the many videos you have posted on YouTube. You are a real bush pilot!



Looking at this video, I understand that you find replacing the bungees easy ... because you remove your seat!



I haven't built my Kitfox myself, only installed a Jabiru engine, but in my plane, the seat is fastened with a hell of a lot of tiny screws along the two tubes that supports it.



May I ask you how your seat is fastened? Do you unscrew all those screws or do you have a better or easier way to fasten it?



Cheers,

Michel

Kitfox III + Jabiru 2200

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