AirMax SeaMax, Elegant Engineering

U.S. PARTNERS – Flanking Jay Cutler, the first LSA
amphibian customer in the USA, are SeaMax USA partners
Malcolm Jones (left) and Carlos Bessa (right).

SPEEDBOAT LINES – Even with its gear sticking out of the
wheel cavities, the SeaMax has smooth lines, nicely accented by
the paint job seen on all the American models.

SPACIOUS CABIN – U.S. representative Carlos
Bessa is slim, but the SeaMax’s cabin will be comfortable
for larger occupants. It measures about 47
inches at the widest point.

LARGE CANOPY — As this view conveys, the SeaMax
has a large canopy built with quality optics and a
slight tint. In Florida, sunshades can be a blessing.

HIDDEN ENGINE – AirMax neatly hides the 100-hp
Rotax 912S engine under this cowling that Carlos
Bessa opens to show the ease of maintenance access.

Photo courtesy of SeaMax USA

Photo courtesy of SeaMax USA

Photo courtesy of SeaMax USA

GEAR ESSENTIALS – A lean and spare design helps
keep empty weight down. People familiar with quality
machining had good things to say after close examination
of these parts.

SWITCHES & BREAKERS – Demonstrating good use of space,
the AirMax places the electric gear knob in overhead panel
(where you won’t bump it) alongside circuit breakers and other
essential switches.

CLEAN PANEL – The panel and its installation is very sanitary
and houses all the instruments a seaplane needs.

SPONSON VIEW – If you haven’t flown a seaplane yet, you owe
it to yourself to gain the experience. Here’s the view you’ll get
from the SeaMax on a beautiful Florida lake.

WATER RUDDER – The SeaMax hides its water rudder during
airborne ops by retracting it into the aerodynamic rudder.
This far aft, the rudder has surprising power.

JUST IN CASE – U.S. rep Carlos Bessa shows the paddle
you get with the SeaMax just in case you need a little
help getting to shore.

GREAT EXECUTION –
Views like this easily
show the attention to
detail in the SeaMax
design.

SERIOUS & COMPETENT
– As his expression
illustrates, U.S.
rep Carlos Bessa is serious about the SeaMax. He gave me a very thorough
checkout, which is the smart way to acclimatize to a new LSA.

Let’s consider light amphibious aircraft – the boathull variety, not floatplanes
– but including both freshly designed, fully built light sport aircraft
along with kit aircraft born of the ultralight heritage.
In the last year, the exceedingly handsome Icon A5 has made quite a splash, literally
and figuratively. However, the A5 is more than a year away from first deliveries
and an order placed today might not be delivered until 2011 or later. Another LSA
amphibian called the Mermaid was designed and introduced by Czech Aircraft
Works of SportCruiser fame. Although five are available in the country, sales have
yet to take off.

Another popular American seaplane, the SeaRey, is moving toward ASTM
approval but remains a kit that asks several hundred hours of a builder’s time. The
simpler and faster-build Aventura models also remain available; this design has
been on the market for many years. Either kit is less costly than a fully built aircraft,
but all seaplanes have loftier price tags to cover their ability to operate on land
or water. Let’s put the cost of LSA amphibians in perspective: The cost of adding amphibious floats to a certified 4-seat general aviation aircraft can be greater than
the price of an entire Light-Sport Aircraft amphibian.

Somewhat behind the scenes compared to the A5 or Mermaid, the little SeaMax
M-22 has won its Special Light-Sport Aircraft approval and started making sales.
With the sleek looks of modern composite LSA, the SeaMax is sized and shaped closer
to ultralight dimensions. The A5 and Mermaid are each pushing against the top
of the allowed weight range of 1,430 pounds for seaplane LSA, while the SeaMax
weighs significantly less. In light aircraft a significant weight difference can bestow
handling and performance advantages.

Light on Its Sponsons

Compared to the A5, Mermaid or SeaRey for that matter, the SeaMax is remarkably
light. When it first arrived in the USA, the SeaMax weighed in at a positively
diminutive 1,144 pounds gross, an unheard-of low weight for a deluxe,
fully enclosed amphibian that looks this good. As it won approval under the ASTM standards for
Light-Sport Aircraft, SeaMax increased capacity to 1,320 pounds. However, since
LSA floatplanes are allowed to weigh 1,430 pounds, the SeaMax still comes in 110
pounds lighter at gross and does even better in empty weight comparison. All this
makes for more useful load.

The amphibious SeaMax tips the scales empty at 750 pounds, giving it a 570-
pound useful load. Even with a full load of 25 gallons of fuel, the SeaMax still boasts
a payload of 420 pounds, enough for two beefy 200-pound occupants plus 20 pounds
of carry-on gear.

The SeaMax M-22 appears physically small from the outside.With the wing chesthigh
for most people, the SeaMax looks tinier than it is and the light weight surely
contributes much to the relative high performance of this flying boat. Light and
small it may seem, but when you step inside, you’ll find the interior to be surprisingly
roomy.

Created by Brazil’s AirMax Construcoes Aeronaticas, the SeaMax is designer
Miguel Rosario’s 22nd design and his experience shows. The M-22 is very well
thought out with many details not present in other LSA. Rosario,
whom I met at Sun ‘n Fun ’07, said that it was first designed for a
wealthy Brazilian businessman and that man wanted it to be a
deluxe aircraft.

Since its introduction, SeaMax sales have reached 90 units flying
worldwide, mostly in Europe where government approval was possible
some years ago. An established dealer in Norway sells the most
but units presently in the U.S. are available for quick delivery. Five
SeaMax LSA are registered in the U.S.

The AirMax’s work to meet ASTM standards relied on Rosario’s
long design history, but he received engineering assistance from a Mr.
DeCastro, widely revered as one of the greatest aeronautical engineers
in Brazil. Rosario also had a serious and talented U.S.-based
partner in Carlos Bessa – who conveniently speaks Portuguese, thereby
aiding communications with AirMax on a daily basis. Bessa is the
quality control manager in the USA for AirMax and sources parts
from Aircraft Spruce, Warp Drive, Lockwood Aviation, Gulf Coast
Avionics and similar suppliers.

The more closely you examine the SeaMax, the more you realize
how well thought out and well finished it is. A technically astute
friend, Matt Taber, observed how small and efficient the landing gear
is, a marvel of few parts that helps restrain weight. Taber also noticed
the numerous stainless steel components used, among other applications,
to secure the horizontal tail plane after shipping. All work
appears beautifully executed.

Other clever ideas include an intake at a wing leading edge opening
that directs air to the hull’s step location to help “unstuck” from
the water’s surface. When the canopy is open, you can remove the
instrument panel top for easy access to the instrument wiring and
plumbing. Further, when that canopy is open, you can see an aluminum
tube perhaps a foot long well forward in front of the passenger.
This allows placement of some lead for additional weight should
the pilot not weigh enough. The Sea Max has a minimum pilot weight of 140 pounds;
lighter solo pilots would add ballast weight. Once the tinted canopy is closed, you no
longer see the tube.

Enviable Complexity

An amphibian is more complex than a landplane, period. Retractable gear, water
rudder, a bilge pump and sponsons result in more to manage along with considerations
of hydrodynamics in addition to aerodynamics. Yet many pilots enjoy the task
and thrive on the added freedom amphibious flying can bring.
Electromechanical landing gear takes about 9 seconds to fully retract. Lights illuminate
the gear position and strategically placed convex mirrors can provide visual
confirmation. SeaMax provides a digital flap position indicator, digital trim position
indicator, electrical fuel boost pump, dual wing landing lights, plus dual throttle
levers and brakes.

The SeaMax’s interior comfort is excellent, with a
slick, speedboat-like finish. Cabin width also belies
the diminutive-appearing exterior; at 47 inches, the
SeaMax is half a foot wider than a Cessna 172. The
canopy optics are excellent and you have 45° aft visibility
through quarter windows.

Leveraged door latches move in a small range and
are therefore firmer to operate and latch with a very
secure feel and sound. The door lever hardware is a
simple and light system with an added little touch –
the interior portion of the door handle has a pointyend,
which is thoughtfully bent inwards so you don’t
snag your clothes on it.

In addition to air vents in the canopy — the common
half-cup-shaped, flip-out ones – the SeaMax has
a second set near your head, tucked away in the
wing root area. The interior ones resemble those on
airliners.

I found the seat belts challenging to adjust; the
adjustment buckles are too close to the seat sides.
This wouldn’t matter if you sit in the same seat all
the time, but it’s awkward when a different-sized
person tries to tighten or loosen the belts. Since my
flight, the company has found a domestic source for
seat belt systems and reports buckle access problems
are history.

When taxiing on land with the canopy open, the
hinge components proved robust; even on a bumpy
turf runway, the canopy moved very little. This provides
plenty of airflow for warm days.
However, the reach to pull the canopy
down requires you to loosen or slip off
your shoulder belts. Alternatively, Bessa
said you could add a strap to the canopy
for easier use.

The 100-hp Rotax 912S easily powered
the SeaMax on land or water.With Bessa
flying, we zipped around on the water at
45 mph. The SeaMax makes a great little
speedboat using only 2,800 rpm to
sustain a brisk pace. Turning in this configuration,
a pilot would employ the
water rudder — which extends from
inside the air rudder (the same as it does
on the Mermaid) – and demands opposite
aileron to keep from sticking a sponson
too deeply in the water.

Rising Off the Water

On full application of power some
water spray may contact the prop so the AirMax utilizes
a Warp Drive metal-reinforced leading edge on
the propeller. Because the SeaMax is a small airplane,
when sitting still in the water, the cockpit side
rails are only inches above the water line, and the
bottoms of the occupant seats are below the water
line. Therefore, while it may be possible to fly in
some waves with experience and good technique, I
consider this a smooth-water airplane. I heard
reports of operations in 1-foot waves, but I believe it
would be uncomfortable when you slowed to idle
speeds in such swells unless you have considerable
experience with the SeaMax.

Using Bessa’s takeoff technique I applied full
power and held the stick full aft until breaking
ground. As the nosewheel lifts, you relax the backpressure
and let the plane fly itself off the surface.
Rotation occurs at about 45 mph indicated on the
Dynon digital PFD. Climbout at 70 mph produced
about 1,000 fpm initially. The SeaMax sustained
climb at about 700 fpm with 10° of flaps.

Repeating the land takeoff on water was similar
except you let it fly off the water with such vigorous
control. The SeaMax’s hull gets on the step in about
100 feet, says AirMax. With continued acceleration,
takeoff follows in another 200 feet when flying solo,
or another 400 feet when flying dual.

During landings with full flaps the aircraft
approaches at 50 mph. A good downwind speed is 75
to 80 mph; this produces about 500 fpm down with
the throttle at idle thrust or about 2,500 rpm.

Water touchdowns proved very straightforward.
The SeaMax responds very well as a boat.
Touchdown was at about 60 mph and it immediately
started tracking straight and true. As I slowed
down, Bessa advised me to pay attention to the transition
from airplane to boat. He says it is essential to
keep the stick full aft to prevent porpoising and possible
upset.

Other pilots who have flown the SeaMax believe
takeoff and landing operations are easier on water.
Maybe that’s because of the openness of landing on
lakes compared to the constraints of hard-surface
landings with fixed boundaries.

Landing on land means you have to make sure the
wheels are down, of course. The action is easy in the
SeaMax, thanks to electromechanical gear using an
overhead-retracting knob. Three green lights at the
top of the panel confirm what you can also visually
check in small convex mirrors on the sponsons, though
you may have to raise a wing to have the
reflection of wheels against the sky and not obscured
by ground clutter.

For water landings, it appears best to use an attitude
landing technique where you establish a speed
via angle of attack and wait for contact. Certainly
this is the advised method when landing on glassy
water where reflection makes it very difficult to see
precisely when to flare. The steady descent to touchdown
feels quite firm on the boathull, but Bessa indicates
the structure easily stands up to the job.

Responsive Handling

Let’s face it. Seaplanes often become more sluggish
than their land-based siblings because of a considerable
extra weight hanging well below vertical center
of mass. Light-Sport Aircraft amphibians will be better
than heavier general aviation seaplanes, but the
SeaMax is above average in its class.

In a general way, the SeaMax reminded me a lot of
the Flight Design CT series (or several other
high-end LSA) in that each machine is a “performance
LSA.” My analogy of a Cessna 172
being a “sedan” and the CT being a sports car
brings nods of agreement from others with
experience in both. Flying a SeaMax evokes a
similar response.

Like any vehicle in the “performance class,”
it may take a bit longer to handle it masterfully.
After my first two flights in the SeaMax,
I was not comfortable enough to take a passenger
in the airplane. Bessa’s partner,
Malcolm Jones, an experienced pilot himself,
said he felt similarly at first. Yet after my
third flight and accumulating nearly 4 hours
I began to feel much more comfortable in the
SeaMax. Given insurance industry requirements
to get at least 5 hours time in type,
most experienced pilots would become comfortable
with the SeaMax in that time.

The SeaMax joystick is nice and light. I
wandered a bit as ailerons and elevator were easier
than the rudder. My initial efforts at mild Dutch rolls
were sloppy, suggesting handling that takes acclimatization.
Rudder control posed some challenge. It has
some momentum that I suspect may have been
induced by the large cabin, a pusher engine, and
closely coupled tail. You need to use the rudder, but
bumping motions of the pedals seemed best.

To smoothen airflow around the large cabin,
designer Rosario put in a long investigation into the
vortex generator tabs seen in many locations. Such
an advanced investigation into airflows is another
example of the thorough approach by the designer.

Bessa likes to use 4,800 rpm on the 100-hp Rotax
912S for normal cruise and that produces about 100
mph. I noted that at 4,600 rpm we showed slightly less than
100 mph. The SeaMax has a negative or reflex position
on the flaps, which adds a few knots to cruise speed.When
we reflexed the flaps, speed crept up another 3 to 5 mph. At
such a lower power setting fuel burn would be quite reasonable,
in the range of 3.5 gallons per hour.

Stalls were modest and came at surprisingly slow speeds. In
my experience, using installed instruments that sometimes
have lower-speed-range error, stall happened at about 43 mph.
Even with a few miles an hour of error, this qualifies as a very
slow stall. Stall recovery qualities were mild with full control
and fast results.

SeaMax in Your Future?

Fully built seaplanes are not your lowest cost options to fly,
but they offer enviable versatility and the LSA seaplane versions
cost far less than their general aviation counterparts.
The whole amphibian LSA costs less than amphibious floats
alone for a general aviation airplane.

Among LSA boathull amphibians, the SeaMax is comparably
priced to other offerings with a current quote of $137,000
base price for a nicely equipped aircraft. And this amphibian
is available on short notice. Some of the SeaMax price is due
to relatively small production, and complexities like
retractable gear that adds cost no matter how efficient the
producer.

Fortunately for the SeaMax, the perceived value may also
be higher due to its versatility, its highly engineered design,
and the deluxe speedboat-like finish. The high quality of
building execution helps justify the asking price, but it’s hard
to put a price on the pleasure a true amphibian like the
SeaMax can provide.