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Weight Saving ? Seat back frame

JanRV6UK

JanRV6UK

Well Known Member
Does current 12 or maybe the 14 have holes in the seat back frame ?

I look at my scratch build set back frame for my RV6 ? and can not help thinking that I could save a few gram (or ounces) if I put a few holes on between the horizontal bends ...

Any thoughts on this ?
 
Jan,

I would discourage you from doing that. The panel takes load along the flat surface not along the plane, when lightning holes are used. That is why they corrugate the surface. Maybe an Engineering will chime in with the science behind this.

Larry
 
Thanks for you comment on this Larry - My point is that as you have pointed out the corrugation takes the load ... so the flat part between the corrugations ... does not do very much ... if a hole is cut .. lets say about 3/4 down from the first bend of the corrugation (the edge of the hole - the centre of the hole would be in the middle between each corrugation) ... and you also press a 45 deg flange on the hole edge ... That might actually make it stronger in bending ? Would be interesting to hear others opinion on this ...
 
JanRV6UK said:
Thanks for you comment on this Larry - My point is that as you have pointed out the corrugation takes the load ... so the flat part between the corrugations ... does not do very much ... if a hole is cut .. lets say about 3/4 down from the first bend of the corrugation (the edge of the hole - the centre of the hole would be in the middle between each corrugation) ... and you also press a 45 deg flange on the hole edge ... That might actually make it stronger in bending ? Would be interesting to hear others opinion on this ...
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You may be right, but I would want an Engineer's perspective. I just think the risk/reward issue is off here. You gain very little in weight saving with this approach.
 
lr172 said:
You may be right, but I would want an Engineer's perspective. I just think the risk/reward issue is off here. You gain very little in weight saving with this approach.
Click to expand...

Go for it and let the rest of us know. :)

The risk bit of risk/reward is not a problem.

The flat portion of seat back is unlikely to fail in a catastrophic danger-to-flight way - and the seat back can always be returned to standard by drilling out rivets and using a new F-637A part.
 
If you want to reduce the weight, cut the excess off of the top. And make them the same width as in the RV4. Sitting in them, you will never notice the difference, but loading baggage will be easier and you will have more elbow room.

With the altered cushions added in, you will lose pounds, not ounces.
 
gasman said:
If you want to reduce the weight, cut the excess off of the top. And make them the same width as in the RV4. Sitting in them, you will never notice the difference, but loading baggage will be easier and you will have more elbow room.

With the altered cushions added in, you will lose pounds, not ounces.
Click to expand...

The -6s are 16 inches wide. What is the RV-4 dimension?
 
lr172 said:
You may be right, but I would want an Engineer's perspective. I just think the risk/reward issue is off here. You gain very little in weight saving with this approach.
Click to expand...

You mean like this?
300 hrs. No problems. Yes, I am a Mech/Aero Eng. The flat sections between the V bends don't do squat for seatback strength. They can be treated just like an I-beam shear web.
Pay attention to the ounces and the pounds will take care of themselves.
I did not calculate weight savings. Number doesn't matter. It saves weight.
I did this kind of stuff all over my chariot. Thats why I came in pretty light for a nosewheel with constant speed.

16459074755414d4b23b13a.jpg
 
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Plate nuts

I noticed you have plate nuts installed in the seat back. Are you willing to share what those are used for?

Sorry about the thread drift.
 
sahrens said:
I noticed you have plate nuts installed in the seat back. Are you willing to share what those are used for?

Sorry about the thread drift.
Click to expand...

I put those in as guestimated locations for attaching some fabric seatback pockets in the future. My wife and I subsequently (at about 6 months into phase 2) designed and she sewed up some seatback pockets to hold the common stuff like tiedowns, cowl plugs and the like. Sorry, I can't find pics of those at the moment.
 
Sorry Bill for late reply - I am travelling at the moment ... Yes that is spot on .. just what I thought doing ... I have been looking at the seat back for a long time and thought it just did not look right ;-) .. it needed some holes ...! I was even thinking about making some dies to form a flange on the holes ... Does not look like you have done that ... Just cut the hole .. Totally agree that all the strength must be from the angles on the side and from the triangles that are formed horizontally ... Thanks for the photo !
 
Jan,
Flanging the holes would be good. I was too lazy. :)
Flange towards the rear of course. :rolleyes:

Lastly, please note that the holes are staggered from row to row. That is on purpose. If you don't, there is a higher chance of the "V" bend collapsing between 2 adjacent holes.
 
yep towards the rear :) ... I was wondering about the staggering of the holes ... Just did a screen grab to keep it in my notes .. when it struck me why you had done it ... then I say your explanation .. Thanks !

Something to get on with when I get home ...
 
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