Matronics Email Lists :: View topic - One bungee on each Main Gear

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

One bungee on each Main Gear

Matronics Email Lists Forum Index -> Zenith601-List

View previous topic :: View next topic

Author Message

dgraham7(at)TWCNY.RR.COM
Guest

Posted: Sun Jun 07, 2009 2:40 pm Post subject: One bungee on each Main Gear

Hello Group:

 I am in the process of buying a 601 HDS with a 80HP  Rotax. The gentleman who built it decided a few years ago to leave just one  bungee on each main gear in order to make grass landings less bumpy. He wrote a  short article about it in the Zenair News. Does anyone have an opinion on  this?  If there is just one bungee on a gear leg, is there a concern of  damage if that one bungee deteriorates ?

 Thanks

    [quote][b]

- 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

larry(at)macsmachine.com
Guest

Posted: Sun Jun 07, 2009 3:48 pm Post subject: One bungee on each Main Gear

Hi Damien,

The objective of having two bungees is redundancy.  If you break one, 

you don't necessarily break up the plane before you replace the broken 

bungee.

Landings with two are none too hard with some practice, but I'd imagine 

a fully loaded HDS rumbling along on uneven or rough runways would probably

break something before breaking the last bungee. I'd recommend the 

redundancy as gear attachments on the center wing are relatively 

delicate without the shock

absorption two bungees provide.  I'd not want to strip out the threaded 

top plates, ding the vertical guides or impact the gear box structure 

below the wing as repairs

could be quite daunting. A double bungee is capable of being bottomed, 

so a single could more easily be as well. One bungee to me is a scary 

concept!



Larry McFarland 601HDS at www.macsmachine.com

Damien wrote:

 	  Quote: 	
		   Hello Group:

 I am in the process of buying a 601 HDS with a 80HP Rotax. The 

 gentleman who built it decided a few years ago to leave just one 

 bungee on each main gear in order to make grass landings less bumpy. 

 He wrote a short article about it in the Zenair News. Does anyone have 

 an opinion on this?  If there is just one bungee on a gear leg, is 

 there a concern of damage if that one bungee deteriorates ?

 Thanks

 *

 *

- 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

stormyflight(at)yahoo.com
Guest

Posted: Wed Jun 10, 2009 9:21 pm Post subject: One bungee on each Main Gear

Hi Damien,

I think that would be a really bad idea.  I am an aircraft designer and have been designing landing gear systems for about 25 years (on UAV's).  A landing gear system is designed to absorb a certain amount of energy during the landing event.  For a light wing loading aircraft like the 601 the limit descent rate is about 6 or 7 feet per second and that equates to a certain amount of energy.  The gear absorbs the energy by deflecting a carefully selected distance with a certain amount of opposing load (in this case from the bungees).  If you remove one of the bungees you are basically cutting the amount of energy the gear can absorb by half before the gear bottoms out.  Once the gear bottoms the loads go up very quickly to the point that something is going to break.  With one bungee your gear would only be able to absorb the energy from about a 4 FPS landing event.  Feels great until you really drop it in and then you have bent something.

Just a tip,

Jim Machin

601XL almost done

--- On Sun, 6/7/09, LarryMcFarland <larry(at)macsmachine.com> wrote:

 	  Quote: 	
		   From: LarryMcFarland <larry(at)macsmachine.com>

 Subject: Re: One bungee on each Main Gear

 To: zenith601-list(at)matronics.com

 Date: Sunday, June 7, 2009, 4:29 PM

 --> Zenith601-List message posted

 by: LarryMcFarland <larry(at)macsmachine.com>

 Hi Damien,

 The objective of having two bungees is redundancy.  If

 you break one, you don't necessarily break up the plane

 before you replace the broken bungee.

 Landings with two are none too hard with some practice, but

 I'd imagine a fully loaded HDS rumbling along on uneven or

 rough runways would probably

 break something before breaking the last bungee. I'd

 recommend the redundancy as gear attachments on the center

 wing are relatively delicate without the shock

 absorption two bungees provide.  I'd not want to strip

 out the threaded top plates, ding the vertical guides or

 impact the gear box structure below the wing as repairs

 could be quite daunting. A double bungee is capable of

 being bottomed, so a single could more easily be as well.

 One bungee to me is a scary concept!

 Larry McFarland 601HDS at www.macsmachine.com

 Damien wrote:

 > Hello Group:

 > I am in the process of buying a 601 HDS with a 80HP

 Rotax. The gentleman who built it decided a few years ago to

 leave just one bungee on each main gear in order to make

 grass landings less bumpy. He wrote a short article about it

 in the Zenair News. Does anyone have an opinion on

 this?  If there is just one bungee on a gear leg, is

 there a concern of damage if that one bungee deteriorates ?

 > Thanks

 > *

 > *

 Email Forum -

 FAQ,

    - MATRONICS WEB FORUMS -

 List Contribution Web Site -

               -Matt

 Dralle, List Admin.

- 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

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith601-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum