John,
Thanks very much for your detailed description of what is needed for an LAA MAUW
increase. The LAA not only make it onerous but also expensive to complete.
Ive not tested my aircraft with a fully aft CG at any weight so I cant speak
to that. But, N914XL has been tested in general flight conditions at 1449 lbs
with CG at 61.267 (185 lb pilot, 135 lbs in the passenger seat, 80 lbs in the
baggage bay & 17 gal of fuel with the results stated in my last e-mail. I wish
you folks the best of luck in obtaining you MAUW increase approval.
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger@mac.com
On May 31, 2015, at 8:07 AM, John Wighton <john@wighton.net> wrote:
An increase in MAUW for the Europa (or any other LAA Permit aircraft) nowadays
requires a significant amount of engineering work culminating in a rational and
fully detailed submission to the Engineering office at the LAA. Long gone are
the days when partial submissions and/or data based on predominantly observation
based in-service history are sufficient to achieve the desired result.
For the Europa there was never (to my knowledge) a full submission made, it's
approval
being in the days when the system was less obstructive. If there was
a fully detailed submission it could be used as a baseline for a MAUW increase,
probably based solely on an extrapolation of the existing stress work and/or
a new interpretation of the factors used in the original.
There seems to be a misunderstanding that an increase in MAUW only affects the
wing, the reality is the entire airframe structurally (and it's aeroelastic
responses)
are influenced by the additional mass.
I started to look at the Europa structure many years ago whilst conducting
stress
analysis on the FLYER magazine aircraft. At that time they not only wanted
to go through the process of building a Permit aircraft but (somewhat
ambitiously)
decided to implement some major modifications. The final result is, thankfully,
flying successfully today (G-MLXP by Mike Davies) albeit without the
BRS mods. The justification reports for that Mod required a simulation (FEA)
of the entire front end of the Europa, which l made on a ply by ply basis
'laying'
up the FE model in the same way that kit is built. The finished model was
stressed using JAR-VLA derived loads (pre CS-VLA) and then the Mods were applied
thereby showing the differences in loads. To cut a very long story short
the LAA finally accepted the Mod after Mike (who purchased the project from
FLYER)
agreed to increase the level of reinforcement around the MLG. The context
of this tale is that my business, as a CAA approv!
ed E1/E2 DOA (with the scope to design and submit type certification for
complete
JAR-VLA aircraft) was unable to persuade (then PFA) LAA Engineering that we
had a good solution. The end result is (most probably) heavier than it needs
to be.
The above is an illustration indicating the amount of justification required to
achieve a successful Mod application. I could add further tales of woe to
illustrate
just how difficult these applications are when made via the LAA.
So, cutting to the chase, to achieve a MAUW increase >1370lbs will require
probably a complete loads and stress analysis of the aircraft as if it were a
new design. It would also most likely require us to conduct material
qualification/characterisation tests in order to alleviate the composite
special factor (1.5) used. Any data relating to the foreign fleet would be of
interest but is unlikely to be of any real value. Had one of our enterprising
US cousins strain gauged their aircraft and conducted flight tests under strict
(CAFE type) conditions (see
http://209.83.103.25/home/flight_reports/europa_classic. (h t m l )
we may have some useful data to correlate the stress analysis with.
My own view (having inadvertently flown my own Europa at >MAUW with a marginally
aft CG whilst in CH) is that it is probably OK structurally and from a stability
and control point of view. Landing at such high weights (admittedly unlikely)
may not work out so well (tri-gear and/or mono).
With swift concentrating on their new aircraft program, which l learned
yesterday
will also be a kit (and then a TC) aircraft, they will unlikely be willing
to devote their own engineering resources to a Heavy Europa Mod (HEM).
Input/opinion from Europa Club members and non-member owners (shame on you,
wherever
you are) on this matter is welcome. If enough people want a Mod (with/without
structural changes) then we can perhaps take it further.
Regards
JW
--------
John Wighton
Europa XS trigear G-IPOD
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