Bud
Thank you for the very complete answer. I should have suspected Flight
Crafters as there were some invoices for builder assistance from them with
the kit. These were for the large glass over foam work and they appear to
have done a beautiful job.
The factory is working on a mod that involves what appears to be a
significant change to the tunnel. As part of this change they have been
through the engineering calculations with the LAA.
My plan at this stage is to keep on with the build and address the gaping
hole later. I expect by the time I need to address the gaping hole the mod
will be out and I should be able to use that for ideas.
I have also joined the LAA and I'll use their engineering services to
review proposed fixes.
Recently I've been looking at a lot of fuselage pictures and with the
number of long slots for control levers most people appear to have cut up
the tunnel quite a lot.
Regards
Graeme
On Tue, Jul 12, 2016 at 9:40 AM, Bud Yerly <budyerly@msn.com> wrote:
> Graeme,
> That was a Flight Crafters mod for the trigear only. However the Berube
=99
> conventional often had it also. The flange was done in four layers. The
> cover was normally done in a four layer, however, that is a structural
> member and in a front end impact the aircraft with this mod will buckle
> right across the canopy bow area if the area is cut down considerably lik
e
> flat from the back to the panel face.
> I have made this cutout myself on many aircraft but frown on cutting the
> tunnel lower.
> To add structure back, I made the center console cover and the flanges ou
t
> of a compressed 6 layer piece of high density 8oz. glass. The cutout has
> to be reinforced with a flange of considerable strength to maintain the
> beam strength of the top. The flange must be six plies in my opinion and
> run down on to the inside of the tunnel at least 3-4 inches overlapping
> each two plies over each other to take the shear of an impact. The cover
> plate is screwed in using #8 or 10 screws about 3 inches apart down the
> sides. That makes for a robust part but it is considerably heavier than
> the original couple of plies and some 3 mm foam.
>
> Note each engineering test firm has slightly different criteria ( I use
> USAF Wright Patterson Data mostly), but a .009 thick glass ply has very
> little compressive strength capability. If you layer say, six compressed
> layers (i.e. no voids), at 15,000 psi for a thin flat hand laid plate you
> only have .050 inches of glass and over three inches, the math says it wi
ll
> hold 750 pounds, but it has little compressive rigidness and will buckle
> under load unless built like an angle iron. So make it thicker right! We
ll
> a uniform thickness with a glass to epoxy ratio of about even may get you
> 100,000 PSI in a perfect sample built to nearly a 90 degree angle, which
is
> quite strong (it is now a longeron), but every hole and cut you put into
> that cover and flange will in fact weaken it. Fiberglass peels in bendin
g
> shear so pay attention to your molding. I=99ve seen some ugly void
s which
> basically makes the structure suspect...
>
> I feel comfortable with a full ring of six plies well lapped onto the
> tunnel wall all the way around and screws every three inches or so. The
> cover plate should be at least 6 plies but it has to be esthetically abou
t
> the same as the piece you took out so it gets a bit thick. If you compre
ss
> the piece you took out to bending failure and you test your filler piece
> and it is stronger, you did your job. I rely on the flanges being
> considerably stronger than the original C section and assume the plate is
> only a shear load. One must not forget to tie the original glass to the
> new glass by hollowing out the edge and filling with flox and assure ther
e
> are no voids. Once complete, you can lift the plane with the panel
> cutout. It is very rigid, and analytically should take the force of a
> modest impact better than original.
>
> I also recommend that Trigear owners and those conventional conversions
> consider a beam be added from wall to wall to make the seat areas connect
> with one another if cutting out the tunnel. That makes a brutally strong
> beam across the cockpit. Not really essential to the Trigear but worth
> considering on the conventional conversion. After all, one does not care
> to have his =99arse be the first item on the scene of the gear coll
apse.
>
> Does my reinforcing work. A nameless client on a cross country impacted
> the runway some 25 degrees nose low and porpoised some 4 times before
> ramming the nose into the tarmac at a 30 degree angle and pushed the nose
> gear leg into the center tunnel. The fuselage was completely intact but
> all three gear were pretzels. Airport observers (mechanics watching the
> approach and bounces) were astounded the aircraft was in such good shape.
> No main structure was damaged. Yes the gear,were changed out and the
> engine frame and nose gear, but more damage to the plane was done grindin
g
> off paint and inspecting it than was done by the =9Ccrash=9D.
This is one
> tough little airplane. If you want to stiffen the nose a bit more, lay a
> 2mm or 1/8 inch foam and glass over with two layers to the area between t
he
> seat and the footwell step. That is the common impact failure area due t
o
> buckling I=99ve seen which puts more stress on the center tunnel.
>
> Nigel is correct. Unless you can prove your mod is as strong as the
> original structure, don=99t fool with it. Put an access panel in t
he belly
> for the center tunnel and leave it alone. If you do cut it out, do your
> homework. I did and I feel confident in my construction and am pleased
> with its performance. I am as a builder my own inspector in the US, and
> frankly the FAA rep just rolled his eyes and said you damn engineers, it
> feels really strong to me so here is your airworthiness certificate. Hec
k
> of a thing we put up with. 419 PL was originally built in 2004, still
> going strong. 12AY has bottom access only because it was faster lighter
> and easier to do.
>
> Why avoid this mod, well it is a pain to sit in the seat and undo a
> zillion screws to get to an item in the tunnel, then drop something and t
ry
> to bend over to feel around for it. The underbelly pan is a bit more
> relaxing on a flat floor with a nice creeper to lay on. However it is
> really dark in there and since gravity works 24/7 wear safety glasses as
> every nut and bolt hits you in the face. It makes for great stomach
> muscles as you continually cycle from the belly to the cockpit unscrewing
> things. I have a love hate relationship with everything in an airplane s
o
> keep it light and simple.
>
> Note that the Europa Trigear mod which cuts out 1/3 of the side of the
> tunnel has less glass than what I do and that was approved. There was al
so
> an approved foam and glass modification to cut down a tunnel approved bu
t
> it did not have a large removable panel.
>
> On the original mono I was always amazed how thin the glass was on the
> center tunnel and as seen in crash photo=99s the tunnel will fail o
n a mono.
> Of course it fails on a very severe impact only. One cannot build to an
> impact resistant aircraft as it would never get off the ground would it.
>
> That=99s my two cents of boring info.
>
> Best Regards,
> Bud Yerly
> Custom Flight Creations, Inc.
> US Europa Dealer
>
>
> Best Regards,
> Bud Yerly
> Custom Flight Creations.
>
> *From:* Graeme Hart <graeme.hart@onecoolkat.com>
> *Sent:* Thursday, July 07, 2016 7:16 PM
> *To:* europa-list@matronics.com
> *Subject:* Re: Fwd: Europa-List: Do you recognise this cockpit mod
>
> Thanks Nigel
>
> While that is bad news it is also good news in that I'm only starting the
> build so it shouldn't be too hard to fix compared with attempting to fix
> when ready to fly.
>
> I am in New Zealand and with our smaller population it is a little harder
> to find people with the experience your inspectors have. We also have a
> much simpler inspection regime.
>
> I'll contact the Europa factory and get their advice on how to reinstate
> the structure. Hopefully it will just be a matter of reinstating the
> missing structure with a flat panel with an appropriate number of plys an
d
> a suitable overlap/bonding to the edges.
>
> On Fri, Jul 8, 2016 at 10:48 AM, nigel_graham@m-tecque.co.uk <
> nigel_graham@m-tecque.co.uk> wrote:
>
>> Hi Graeme,
>>
>> I don't like to be the bearer of bad news but that mod was not (and neve
r
>> will be) approved in the UK. The centre tunnel is a critical structural
>> component and by removing such a huge area of the box section, most of t
he
>> strength will have been removed with it. If it is your intention to buil
d
>> the airframe to flying condition, I would suggest involving your inspect
or
>> (one with proven composite skills) to advise on reconstructing the tunne
l.
>>
>> The Europa has no longeron like structures forward of the seat moulding
>> and it is only the tunnel that prevents the fuselage snapping off in the
>> event of a high "G" arrival. Typically, the fracture initiates at the sh
arp
>> corner at the lower edge of the windscreen, propagates down the fuselage
>> sides and across the floor. I have attached a picture of such a failure
to
>> help concentrate the mind (I have more!).
>>
>> Nigel
>>
>>
>>
>> On 07/07/2016 21:51, Graeme Hart wrote:
>>
>> Hi Alan
>>
>> It is a trigear and came as a trigear from the factory.
>>
>> It looks to me like the plan was to put a removable panel on the top.
>>
>> I have attached a better picture.
>> On 7/07/2016 11:14 pm, "Alan Burrill" <alanb@dpy01.co.uk> wrote:
>>
>>>
>>> Tri-Gear or Monowheel?
>>>
>>> Alan
>>>
>>> GOBJT
>>> > On 7 Jul 2016, at 11:35, Graeme Hart <graeme.hart@onecoolkat.com>
>>> wrote:
>>> >
>>> > Hi All
>>> >
>>> > I have a kit that started out around 1999 and has been worked on by a
>>> number of builder since them.
>>> >
>>> > Does anyone recognise the mod that has been done to the cockpit. A
>>> lot of the top of the centre console has been cut out and reinforced ar
ound
>>> the edges.
>>> >
>>> > I'm hoping that this is a recognised mod and someone can point me at
>>> documentation on what was intended.
>>> >
>>> > A picture of part of the cutout section is below (sorry I don't have
>>> one of the entire cutout)
>>> >
>>> > I'd appreciate any leads on how this mod is intended to work. Also,
>>> with this large hole in the top do you still need the fuel valve access
>>> panel?
>>> >
>>> >
>>> > Thanks
>>> > Graeme
>>> > <20160705_174300.jpg>
>>>
>>>
>>
>>
>>
>
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