The recent submittals
to the FAA regarding AWE by existing aviation interests, like
AOPA, EAA, NAAA, and some individual experts, give a
clear picture of their concerns. Conspicuity is the immediate top
issue, with the tether in particular as the biggest fear. General
aviation is also feeling squeezed down by Class B airspace from above, and towers and AWES from below.
EAA
and NAAA reveal distinct low-altitude aviation sectors that would be
disproportionally impacted by AWES clutter and sprawl. Brian Rau
identified a subtle danger that an approaching pilot might spot an AWES
kiteplane, but fail to identify it as a tethered object, and thus fly
into an unseen tether.
The
FAA call prompted normally secretive AWE players to disclose
interesting information. Many R&D teams are having trouble
with FARs requirements. KiteLab Group's designed-in regulatory
compliance is the clearest exception to the trend. Compared to the
suave EU input, American AWES submissions mostly look like they were
composed on crack, full of typos and gaffes; oh well, whatever. The US
aviation community, on the other hand, did a very professional job
zeroing in on critical safety gaps.
AWEC's
submission is mostly a cut-and-paste of Makani's plea to avoid key
provisions Part 77, even while claiming to be "eager" to be
under these rules. A surprise
is the presence in the inclusion of Altaeros, WindLift, and
Highest Wind signatures, who were not known to be AWEC members,
which means that AWEC's onerous pay-to-play requirement
was met or waived.
News
in Makani's submission is that they finally concede a
need for human pilots. Their systems are described as "fully" or
"completely" "autonomous", which is not strictly true. "Highly
Autonomous" is a more honest claim, as Wing7 requires a
pilot-in-command to make all sorts of critical control decisions, like
reacting to unexpected failure-modes or sudden weather changes. The
other two large and jumbo aircraft don't even exist,
yet again Makani marketing-speak fudges
present-tense semantics. Like SkySails and KiteLab
Group, Makani now invokes SCADA, which is supervised
autonomy. Unlike SS and KLG, the Makani pilot may only have five
seconds or so to save the aircraft before a crash.
Makani requests
exemption from key Part 77/101 marker requirements,
as "debilitating to performance". They ask to
to strobe marker lights at the top and bottom of each loop, to
mimic a compliant tower. A problem is
that this "virtual tower" will wander up to two
miles in weathercocking, and the natural kite-loop cycle is longer than FAA flashing specs. This makes crossing paths more likely with airplanes presuming it to "stand still", or mistake it for multiple separated objects.
The flashing lights even precess during vaning, reversing
apparent direction capriciously. Also, from most angles, the
virtual tower will appear to lean.
Makani baldly proposes to not mark its tethers at all, reasoning that they are merely like unmarked mast guy-lines. Again, the geometry of weathercocking is quite different, that as the virtual tower wanders, the imaginary guy wires ultimately encompass a volume comparable to multiple masts.
A
daytime perceptual danger to looping
kiteplanes is that as an approaching
VFR pilot scans the sky looking for
other traffic. they can fail to glance at just the
right moments to spot the kiteplane at the top of its loop
pattern, completely overlooking it before mid-air
collision. Taken together, so many flaws in conspicuity
design seem fatal, especially if EAA and AOPA rebel.
Makani's
scaling strategy is once again shifting. From the
current 20KW experiment (Wing7), a 600KW (M600), and a
5MW (M5) kiteplane are announced. This critical path is
equivalent to going from an ultralight, to a DC3, to ultimately a 747
size wing. It would take about a thousand of these
giant kiteplanes to power a major city, at an operational
intensity comparable to the busiest airports in the world. Don't
tell AOPA or EAA this.
We
can now roughly estimate Makani's capital cost structure based on
the provided aircraft weight predictions using Felker's estimate
of $500-per-pound cost for modern production aircraft. Thus Wing7
would run about $75,000 for a 22KW rated device, M600 would run about
$1,400,000 for 600KW rated, and M5 about $7,000,000. Presuming a
big advantage in accessing better wind seems canceled by high aviation O&M (especially aviation insurance). Thus Makani's complex AWES architecture does not seem competitive
with conventional wind, much less "cheaper then coal". This is not
even counting the incredible land cost of the sprawling
Makani operational geometry (with almost 10X core
footprint with a land "stand-off" (crash-zone) or the
triple-cost rule-of-thumb for offshore O&M. Makani relentlessly
pushes "material efficiency" compared to conventional HAWTs, but
when you factor in Felker's $5-per-pound for HAWT's, Makani's claims
seems unjustified. We await their formal economic study to ARPA-E.
Makani
barely notes radar clutter as a design concern, announcing radar
studies to quantify just how brightly their aerobatic carbon fiber
E-Flight kiteplanes sparkle, while also supposing that they can
substitute non-reflective materials. Internal electrics and conductive
tether will still reflect. If Makani is forced to go for for full-on
stealth, that's not cheap. Lightning and ESD is claimed will meet
MIL-STD, a very high standard; not cheap either.
WindLift
is a full-on MIL-STD AWES which generally makes for an FAA friendly
approach, with an admirable "sense and avoid" capability. Sadly,
military specifications are mostly unsuited to civilian markets. A
wistful notion stated is that AWES can become "common on the
battlefield", even as most of the world deeply hopes to make the
battlefield itself uncommon.
SkySails'
kite is radar transparent, but depends on a conductor in its tether to
its control pod, both of which will reflect. One would likely see
the the tether coming and going on radar, the wandering catenary creating an illusion of a dim moving flying object up and down its translating trajectory.
Alteros also has a conductive tether, and predicts some rotor RCS. presumably due to carbon-fiber blades. Altaeros surprises
by disclosing a high-density array option with AMWTs spaced as close as
five rotor diameters apart. They also are trying to get-off-the-hook on
tether lighting, citing spooling conflicts.
Highest
Wind hopes the FAA will give its farm systems a pass on Part 77/101
essentials, even as 1700 NAAA members lock N' load to oppose even
complaint AWES conspicuity.
Wayne German's
submission was so exotic it had to be resubmitted several times,
with Joe's final intervention, before the US Government
finally caved. Its the usual mix of brilliant ideas cloaked in
improbable details, a sort of Unabomber-Nostradamus screed worth
rereading many times to hunt down every last clue. KiteLab's
AWEIA-sponsored TACO, at 44 pages, would have matched the entire output
of the rest of the field, had not Wayne been similarly prolific.
KiteLab
Group filed in the name of all affiliates. If you are in harmony with
the principles set forth, consider this your submission, but register
your intent with us. Some key AWE players failed to respond to
this call, but they should go ahead and file, if they intend to operate
in the "real world". Also missing was an updated edition of Doug's
AWE Primer to NASA...
