Elevator Bungee Cord

Aircraft Legacy Sonex
1

Elevator Bungee Cord

Posted: Mon May 20, 2024 9:13 pm

by Sonex1243

Working on the control column install and wondering where others have sourced their bungee cord from and what brand has been used. Thanks for the help

Ken

Re: Elevator Bungee Cord

Posted: Mon May 20, 2024 9:59 pm

by peter anson

Yachting suppliers sell bungee cord but maybe that’s not such a useful suggestion if you live in Wyoming. I also used a rope cleat intended for a yacht as a way of making the tension easily adjustable.

Peter

Re: Elevator Bungee Cord

Posted: Mon May 20, 2024 10:32 pm

by BRS

Peter I like your thinking, borrowing from one industry to repurpose for another use.

Re: Elevator Bungee Cord

Posted: Tue May 21, 2024 12:30 am

by Bryan Cotton

I bought bungee cord for my sailboats.
https://www.sailrite.com/Shock-Cord-3-16

Many diameters and colors available. They deliver to Wyoming I’m sure.
Edit:

Image
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Re: Elevator Bungee Cord

Posted: Tue May 21, 2024 9:35 am

by builderflyer

Ken, I began flying with bungee cord before replacing it with springs which work well for the intended purpose.and seem to require less attention over time.

Art,Sonex taildragger #95,Jabiru 3300 #261

Re: Elevator Bungee Cord

Posted: Tue May 21, 2024 7:24 pm

by Sonex1243

Great information, thanks for the help everyone!

2

Today I removed the seat and discovered the elevator bungee. After 20 years it doesn’t do much, and I wonder what I should replace it with. Should the cord engage at a neutral position and add just a little back pressure or should it pull the stick all the way back? Or some else entirely?

3

Are you talking for the Aeroconversions trim system? Sonex sells the springs.

The dial-a-trim manual can be found on this page:

My fixed spring pulls the elevator nose down, and the spring connected to trim pulls it back up.

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4

Nothing so complex. The red thing in this photo.

bungee - 1
bungee - 1480×640 66.8 KB

5

Is anyone using bungee cord for in flight aileron and rudder trim??:smiling_face_with_horns:

6

For me, I would not put bungee cords on rudder and/or aieleron controls, and in stead, use tabs on those surfaces to get neutral az/el/rot , hands off, only imho. loading most likely will shift neutralness anyway. you dont want to fight bungees on top of air loads. just my view!

7

Hi SirPD,

My Sonex is set up for one person (me 70kg). In Cruise she flies straight & level and I don’t need any rudder inputs even for gentle turns (Ball remans centered).

I did my BFR the other day with my instructor (78kg). This was the first time I had a full sized adult on board.

That I had to hold some left stick, to counter his weight ,was not a surprise however having to use quite a bit of left rudder was. My turns, take-off & landings were far from my best (I still passed).

My last aircraft had a one way bungee on the aileron control. One way because it was only used to counter the weight of the occasional passenger. The bungee strength was just enough to counter the change in aileron required and was easily adjusted using a sailing “cleat’. No additional rudder inputs were required. This very simple system worked well.

While the principal is sound (works) I have not yet worked out how I would implement it on my Sonex - hence the question.:smiling_face_with_horns:

8

Now I understand where you are, and I do not have concerns about what you were proposing, as your well experienced in the bungee cord uses. I do not have that experience, and that was my concern. Carry on, as they say, and let us know how things work out!!

9

Thanks SirPd.

I am a tad surprised that others have not come across this “problem” and come up with a KISS solution rather than the costly/ relativly complex electrical/electronic in flight adjustable trim tab.

Sure the trim tab concept is “tried & true” particularly on larger & certified aircraft . The Sonex is a very simple, light weight, aircraft, seems a shame to me to be compromising this concept with unnecessarily complex system - each to their own.

I have been contemplating the install for the bungee system.

Ideally, for ease of pilot access/operation, the cord should come up vertically. Each cord will need a “cleat” at the pilot end and at least one light weight pulley to change direction of operation/pull.

All of the above is doable BUT if at all possible I would like to avoid drilling any more holes (especially in the skin - aircraft painted). This reluctance makes a simple install. complex. I will take the time to think it through.:smiling_face_with_horns:

1 Like