Sonex legacy floor
Posted: Thu Oct 28, 2021 11:17 pm
by zzdeck
When getting in and out of our legacy Sonex, we’ve been wary of standing on the seating area. We try to step on areas with support beneath. We are in the process of building and have not purchased upholstery yet. The seating area is a sheet of steel anchored with piano hinges at the back (under the spine) and front (under the knees). Between those two points there is no support (it feels like you are sitting in a hammock) and there is a pretty significant gap between what you and the airplane floor.
Have we have missed something? Should the seating area have additional support beneath? It seems flimsy, but perhaps it’s stronger than we think.
Comments, please.
Re: Sonex legacy floor
Posted: Fri Oct 29, 2021 8:39 am
by DCASonex
Unless somebody messed with your kit, that “sheet of steel” is actually aluminum, and nothing goes under it.
David A.
Re: Sonex legacy floor
Posted: Fri Oct 29, 2021 9:18 am
by Scott Todd
Shouldn’t you be stepping on the spar to get in?
Re: Sonex legacy floor
Posted: Fri Oct 29, 2021 10:02 am
by XenosN42
DCASonex wrote:Unless somebody messed with your kit, that “sheet of steel” is actually aluminum, and nothing goes under it.
David A.
True! And I would add that it is designed to be stepped on.
Re: Sonex legacy floor
Posted: Fri Oct 29, 2021 10:57 am
by builderflyer
The part of the Sonex that is most structurally abused in the entire airplane is likely along the “spine” of the seat pan. Originally, the hinge along the spine was attached to an unreinforced channel section. Before long, through a Sonex service bulletin, an extruded aluminum angle was added to the top of the channel section for additional strength in that area. So the next failure on my particular Sonex was the hinge material itself that is attached to the extruded angle. Some of the hinge loops began to break off and sections of the hinge had to be replaced. The next point of failure, which has just occurred, is a crack in the seat material itself along the bend of the spine adjacent to the hole through which the seat belts pass. I’ve added a couple of reinforcements in this area and we’ll have to see how long before another failure occurs here.
If I were to rebuild the entire seat pan on my Sonex, or if I was building a new Sonex it would be my intention to do two upgrades and they are: (1) add a doubler skin along the entire length of the spine, bent to match the corner of the pan and riveted to both the bottom and back of the pan (note that some builders have used a thicker material for the entire seat pan but they haven’t said how that has worked out for them) and, (2) use a structurally upgraded hinge material along the entire length of the spine. The remainder of the seat pan installation has never been an issue.
Just my opinion,
Art,Sonex taildragger #95 (800 hours),Jabiru 3300 #261
Re: Sonex legacy floor
Posted: Sat Oct 30, 2021 11:49 am
by pappas
Having built and flown both the Legacy Waiex and the B model, I can say that I never liked the “sling seat idea”. The B model has structural ribs below the seat pan that are very much like the style that was in the RV-8 that I built. I don’t doubt that a builder can fabricate seat ribs similar to the B model that would eliminate the problems with the sling seat.
I remember that the sling seat could interfere with the pitch control components of the aircraft if additional weight was in the seat. I had to make adjustments for that before I could make a safe first flight. Designing and adding seat ribs for the legacy models is the best bet in my opinion.
Re: Sonex legacy floor
Posted: Sat Oct 30, 2021 4:57 pm
by Skippydiesel
All very interesting, to a new Sonex owner (will take possession within the next 2 weeks).
My question would be; is this space readily usable/accessible ie can it be used to store things like the aircraft tie down kit, spare fuel filter, firsts aid kit, etc??
Re: Sonex legacy floor
Posted: Sat Oct 30, 2021 5:22 pm
by Bryan Cotton
Skippydiesel wrote:My question would be; is this space readily usable/accessible ie can it be used to store things like the aircraft tie down kit, spare fuel filter, firsts aid kit, etc??
Would be bad from a crashworthiness perspective.
Re: Sonex legacy floor
Posted: Sat Oct 30, 2021 6:50 pm
by GordonTurner
Good space for remote mount radios, agars, etc. it’s not easy to get in to in the sense of baggage storage.
Re: Sonex legacy floor
Posted: Sun Oct 31, 2021 6:32 am
by Skippydiesel
Bryan Cotton wrote:
Skippydiesel wrote:
Would be bad from a crashworthiness perspective.
Care to expand/elaborate.
Re: Sonex legacy floor
Posted: Sun Oct 31, 2021 6:37 am
by Skippydiesel
GordonTurner wrote:Good space for remote mount radios, agars, etc. it’s not easy to get in to in the sense of baggage storage.
Thanks for this.
I take it the space is not readily accessible ?
Could it be made/modified to be more accessible ?
My current aircraft (ATEC Zephyr) has a handy space below each seat, not access able during flight, that I can use for all those little things that might be required eg aircraft tie down bag, first aid kit, etc
Re: Sonex legacy floor
Posted: Sun Oct 31, 2021 10:26 am
by Bryan Cotton
Skippydiesel wrote:
Bryan Cotton wrote:
Skippydiesel wrote:
Would be bad from a crashworthiness perspective.Care to expand/elaborate.
The space under the seat acts as a crush zone for a high vertical impact. When you put stuff under there, you lose the crush zone.
Re: Sonex legacy floor
Posted: Sun Oct 31, 2021 11:08 am
by pappas
The area under the sling seat may act as a “crush zone”, I don’t know. However, Sonex decided to go with a more conventional seat design on the B model. So, I would assume that they factored that into the new design if it was a consideration for the legacy. I tend to think that the sling design was more likely a compromise to simplicity and weight savings than a crashworthy item.
I fabricated access panels, secured by screws and nutplates, into my B model seat pan to give me access to the remote radio, transponder, A/P servo’s and trim motors which fit nicely under the seat and only get looked at during maintenance or conditionals. I am much happier with the new seat design than I was with the sling.
There is certainly room under the seat for a travel tool kit, but it would be easier just to sew up a baggage sling behind the seat and keep it in there. The seats are always a bit of a pain to remove.
Re: Sonex legacy floor
Posted: Sun Oct 31, 2021 4:54 pm
by Skippydiesel
pappas wrote:The area under the sling seat may act as a “crush zone”, I don’t know. However, Sonex decided to go with a more conventional seat design on the B model. So, I would assume that they factored that into the new design if it was a consideration for the legacy. I tend to think that the sling design was more likely a compromise to simplicity and weight savings than a crashworthy item.
I fabricated access panels, secured by screws and nutplates, into my B model seat pan to give me access to the remote radio, transponder, A/P servo’s and trim motors which fit nicely under the seat and only get looked at during maintenance or conditionals. I am much happier with the new seat design than I was with the sling.
There is certainly room under the seat for a travel tool kit, but it would be easier just to sew up a baggage sling behind the seat and keep it in there. The seats are always a bit of a pain to remove.
Great response - I will look closely at this area in my my new Sonex. Having a space that is very close, if not right on the C of G, that can be utilised for locating remote electronics, infrequently used supplies, etc. is very handy. The aircraft I am getting is a Legacy model but has already incorporated many B model improvements. The seat base is a sheet of aluminium (nor sling type) and already has a luggage bag fitted behind the seats (behind the C of G)
Re: Sonex legacy floor
Posted: Mon Nov 01, 2021 11:50 am
by n502pd
Yet another chime in for me this am! I too had the seat pan start tearing , from my non standard size and weight. Ingress is designed to stand in the seat pan, and over a short time, the pan began to tear near the seatbelt entrance too. i fabricated 1x1x1/8 angle aluminum left over fron the build, and ran two supports for pic and pax seats from the spar box to the centerline of the rear,lower hinge. this solved the problem of breakikng the seatpan, added butt support while seated, with a much better ability to actually stand in the seat for ingress and egress. I have had no further deterioration of the seat pan in over 50 hrs.
Re: Sonex legacy floor
Posted: Thu May 23, 2024 8:41 pm
by Skippydiesel
I have found my Sonex to be disappointingly short on storage space.
I now plan to cut two, slightly rectangular holes, in my seat base and have a hinged flap on each.
The space below will have to be modified, using thin plywood walls, so as to prevent items from interfering with the flight control system.
This space will hold my infrequently used, always carried, items eg tool kit, jack & tyre repair, first aid kit, etc
On long trips, I carry two collapsible 20L fuel bladders & a Mr Funnel - they will find a home in a purpose built, removable tailored box in the right footwell.