Harness attach points

[Sam Buchanan]

I continue to get questions about how to attach the harness to the airframe.

(I'm always happy to help but instead of sending me private email, asking these questions on the forum will allow info to propagate to all forum members.....)

Here is a photo from my site showing the attachment of the shoulder harness:



The lap belts are attached to gussets that were added to the junction of station three cabanes and the lower longerons. You can see them in this image:



The harness shown on my website is the one sold by Great Plains. It is distributed by Empi, the VW/dune buggy folks and I used it for a couple of summers. But I didn't like the way the shoulder harness was attached via loops to the lap belt. I much prefer the latch on the RV-6 belts I've used for 15 years so I upgraded to a Vans RV-7 4-pt harness:

http://www.vansaircraft.com/cgi-bin/store.cgi?ident=1406647178-448-552&browse=airframe&product=seat-belts

This required an extension for the shoulder belt attachment but I much prefer the Vans harness because it allows the buckle to be centered in your lap and the shoulder belts disconnect from the lap belt for easier entry/exit.

[Sparrow]

Hi Sam,

Thank you for the great information.  I do like the attach points you are using.  I will drag out the welder and put those areas in.
Did you have to lengthen your shoulder harness belt by adding webbing to it or did you have someone do this for you?  If you sent it off to get it modified please let me know where that would be so I can modify mine at the appropriate time.

Regards,

John L.

[Sam Buchanan]

John, I had the RV harness in the shop along with other assorted bits and pieces of harnesses. I used some stuff I had on hand to make the RV harness work.

<begin sermon>
Don't try to blindly copy what I or somebody else has done with their plane. My plane reflects my ideas/experience and materials on hand and may not be the best path for another builder.  (Example; several Eaglers, including the designer, don't agree with my method of anchoring the shoulder harness.....even though I'm right......    )

Spend some time deciding how you want things to be done and research options available to you. After some homework you may find a different harness works better for your application. Lots of possibilities out there......enjoy the journey!
<end sermon>

[Sparrow]

Thanks Sam,

I agree with you concerning each person and the uniqueness of ideas.  I am a big fan of appropriately sized gussets.  They attach as well as supporting the framework around them.  If your rear attach point had been a gusset with appropriately rounded attach point it would provide a point of attachment that would not bend, as a tube, but would tend to try to pull the entire frame forward with it.  I also reviewed the FAA instructions on the shoulder harness attach angles months ago and I feel the straight back provides a more reasonable control of the upper torso than anything that exceeds the 30 degrees into the up position.  I have to think about it for a while before I feel comfortable.  I will be ordering the harness and piece it together here.  Thank you again Sam.  PS:  Years ago a friend of mine was building a KR2 and he ran the attach strap to a hard point just in front of the vertical stab.  He said he likes to have torso control and an area that can slowly absorb the impact forces as it collapses and thus limit the impact to the person.

John L.

[Sam Buchanan]

I'm totally comfortable with the shoulder attachment via the short tube at the cluster, just can't imagine that tube yielding before the harness (or pilot) breaks. The controversy has been over the angle at which the harness attaches.

By the way, the RV shoulder harness attaches via a cable that is bolted to the fuse longeron about half-way between the cabin and tail. That gives proper angle and crush structure as you mentioned. But since force is related to the square of speed we aren't dealing with the deceleration forces that are present in a heavier/faster plane so having the harness secured to a strong, non-flexing location near the pilot should be sufficient for our mission.

I'm confident you will have a good solution because of the thought you are applying to the harness. Build on!