SonexBuilders.net

I've been sitting on cushion squabs and pads of memory foam to help deal with the cold - winter flying the Sonex.

Came across these at a sale price. Memory foam, and if you flip it over and a little needle work on the "notch" - this can be made to work for a dual stick machine. I'm going to dispense with the bench padded nylon and use these which offer thicker memory foam and more insulation. In effect the finished look will be an aluminium bench and back with upholstered squabs velcroed in place.

Each cushion weighs 1.5lb

Not for everyone - but at this remaindered price....

https://www.bedbathandbeyond.com/store/ ... ey/5374570

Here's how that worked out.

Hey Graeme,

So ..., are the new cushions comfy? I can tell I'm going to have a hard time making the Onex comfortable. It looks like those cushions have a zipper in the back to allow one to over stuff or change the foam. Interesting.

Wes

Comfy? Compared to sitting on a cold aluminum bench with a thin layer of foam in ballistic nylon. These contoured and shaped memory foam cushions are a squillion times better! For a moment I felt a little "perched" - and then the foam warmed up and contoured and I fitted right in.

Yes there is a zip and yes you could change the stuffing but that wasn't really the point - These were relatively cheap as they were on sale and are contoured and ready to go. The stitching of the cover is quite a sophisticated shape to match the contoured foam - not sure you would want to mess with them.

I did notice that Bed Bath and Beyond had a number of other offerings - so I am sure you could try a few out to get something that worked / fitted.

These are a bit thicker than what was there before - not a problem for me - the builder of my plane was tall and had put in the low seat so he would fit in. Even sitting on a slightly thicker cushion - I still easily fit. And the sight picture didn't change enough to mess with my landings.

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One issue that I'm not quite sure about is if they would pass an FAA Burn test. They have a consumer fire rating on them - not sure how that compares to the FAA test. But it is sure as heck a whole lot better than the nylon and foam that came with the plane - A match on a scrap of that confirmed it would not pass any test - except the "burns well" test.

The problem with all sling seats is that they don't support your back properly. They end up being concave whereas your back needs to be a bit of support in the right place. I carved a couple of these from blue styrene foam. They just slip in behind the old seat back cushions. I have flown up to 8.5 hours in a day using one and had no back problems. Without them, 2 hours was my limit.

From memory, the maximum thickness is 30mm tapering down to a few mm at the ends. I think the maximum thickness is about 150mm from the bottom.

Peter

I also think my home made upholstery will not pass the burn test. Good thing this is experimental. If God forbid my seat is on fire, I wonder how much of a factor that will be.

For those of you into upholstery take a look at wheel chair cushions. They come in different widths and they are made for sitting 24/7. I had my cushions made by an upholstery shop to my dimensions and they are great, but not cheap.

Hi Guys,

Comfortable seating is a big deal for me. Squirming around ruins the fun. I was able to make the factory upholstery very comfortable in my old Sonex with some custom stuffing. As I recall the bottom layer was high density (hard) foam followed by a layer of green "CONFOR FOAM " from ACS and then the original foam on top. I remember it being hard to stuff it all in but with very good results. For lumbar support my wife sewed up some foam with velcro on the back. I found the sweet spot and stuck it in place. I could sit in that plane all day with no problem.

Anyway, It's going to be a challenge. Through some sort of genetic defect I have no arse at all so the seat cushion will have to be thick and conforming. The seat pan in the Onex is way too low for me so the first step will be figuring out the right seating height. I can't really do that until the canopy is installed, can't do that until the baggage compartment is installed, can't do that until I paint a little, can't do that until the humidity comes down, can't do that because, well ...

Right now I'm just keeping an eye on what others have done to get some ideas.

peter anson wrote:I carved a couple of these from blue styrene foam.

Peter, how did you carve the foam? Electric carving knife?

Wes

Peter, how did you carve the foam? Electric carving knife?

Some carving with a long knife, some sanding with a flapper disc in an angle grinder and lots of sanding with coarse paper. A belt sander would do a much better and faster job but I didn't own one at the time.

Peter