SonexBuilders.net

As the normal way to get into a Sonex or Waiex is to stand in the seat, quite a lot of concentrated weight must be exerted on to the 0.025 seat pan and the piano hinges that hold it in place. Given that the twin stick variant has two quite large holes in the front part of the seat pan for the control sticks, as well as the slot at the bottom rear for the seat belts etc., I wonder whether many operators have noticed some stretching of the seats and pulling at the hinges over time.

Has your seat stretched over time in use? If so, does that present any problems? And if so, what have you done about it?

Tim Mobbs
Sonex #1555 standard gear
Aerovee #0672

It's a good question. It's worth mentioning that on the Waiex (or any lowered seat mod I would guess) it's important NOT to step in the center/middle of the seat. It presses the seat down onto the front lip of the "hat" that covers the stick-to-idler pushrod and can bend things up a bit (ask me how I know.)

The very first thing I explain to riders in my plane is "we don't stand on the upholstery". Its meant to be more a cautionary thing to not step in the middle of the seat pan. I ask them to step over the side and put their foot on the spar carry-through and then sit on the cockpit cross brace. Slide over to the far side and then ease into the seat.
I don't feel the pan hinges move at all. I have 457 hrs with lots of two up time and all my hinges look very good when they get inspected.
Naturally, the pan flexes but there is no noticeable sag.
Personally, I wish the entire seat design was a touch more robust but, that could be a statement made about many things in life. My main concern would be the toughness of the seat arraignment in a hard off airport crash/unscheduled arrival. Very little to crush between you and the bottom of the plane.
Like everything, its a compromise I guess.

Larry
Waiex 121YX, 457 hrs

I made my seat pan out of .032. The .025 just looked way too flimsy. My passengers and I walk all over the upholstery (and seat pan) with no issues.

Larry

Thanks for your reply. But I am slightly puzzled when you say "The very first thing I explain to riders in my plane is "we don't stand on the upholstery". Its meant to be more a cautionary thing to not step in the middle of the seat pan. I ask them to step over the side and put their foot on the spar carry-through and then sit on the cockpit cross brace. Slide over to the far side and then ease into the seat."

Do you mean by "the spar carry-through" the spar tunnel? If so doesn't your upholstery cover that and the rest of the seat pan, or can you easily lift it up while the passenger gets in?

Best wishes
Tim Mobbs
Sonex #1555 Standard Gear
Aerovee #0672

I just tell people to stand on the upholstery to get in :-) My only caution is don't grab anything plastic (ie - the windscreen or canopy).

Hi All,
We had already built our seat pan for our waiex, and noticed that is was flimsy at only .025. Years ago on the flight line at Oshkosh we talked to Dave Webber from dynon who was showing us his beautiful sonex. He suggested making the seat pan out of thicker material, really makes a difference he suggested. Much easier getting in/out and more comfortable. We added two pieces to our pan , both .025, one on the bottom between the hinges, the other on the back between the existing hinges. This really stiffened it up. The hinges have held up well , no problems. We have the dynon set up w 2 servos for pitch and roll. We also added a 1X1X 1/8 aluminum angle on the rt side of seat pan. This was for the roll servo (dynon roll servo SV-42 EL extra long arm) to prevent seat pan flex. Otherwise with a passenger in rt seat the roll servo arm was rubbing on the seat pan. Things are tight underneath the pan. Especially with servos. . We have the sonex leather seat pads with Oregon aero seat pads on top. Comfy. A little weight for all this? Yes. But sure is nice to step in/out and sit in!

WaiexN143NM
Michael Radtke

Tim,

Yes, I meant the spar carry through tunnel. I guess I'm adverse to having wet shoes and mud right where I want to plop down my keister. Minimal contact with the upholstery.
I have the Dynon AP servos in my Waiex also. Never had an issue with the roll servo hitting the pan. Hmmmmm?
Now I'll have to look when I'm doing my condition inspection. Honestly never had an issue.
Michael I'm jealous of your Oregon Aero seats but they just won't work for me. I'm 6'3" and headroom is precious.
I have plenty to keep me busy as it sits. Installing new CAmit engine end of January.
While I have engine off and weight is at a minimum, I'm servicing my gear legs, axles and putting my hydraualic brakes on that have been sitting in the hanger for 3 yrs.
My mechanicals have given excellent service. I simply can't stop changing things; bolting on new toys.
I'm trying to take something off for everything I add on but the weight of the plane has increased now, 19lbs since first certificated. That's the trade-off for newer engine, different brakes, and auto pilot.
Pretty soon she will be a single passenger airplane that does everything very well except carry a big passenger load.

Hi Larry,
Best thing to do is sit in the right seat and move the stick left/right , make sure that you don't feel the top of the servo arm rubbing against the seat pan. Dynon warns to check for this in their install hardware kit. If not then ur good to go. If u do feel any rubbing then install the alum angle rt side edge.
Cheers!
WaiexN143NM
Michael