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THE
RV-12 FLIES !
November
09, 2006
Ken Scott
Just like we promised back in August,
the RV-12 flew in October -- October 40th, to be
precise. At about 10 a.m. this morning Van made the first flight
our new airplane, launching into cold sky filled with layers of
puffy clouds. With a 10-15 knot breeze, it certainly got off the
ground easily and climbed well, passing almost inaudibly over a
bunch of interested spectators—most of our engineering and
tech support staff — about half way down the runway.
Van circled the airport at about
2000’, followed by Ken Krueger and Rian Johnson in the RV-9A.
He sampled the flying qualities and slow flight
characteristics…even from the ground we could tell the roll
rate was pretty snappy. Van said it felt at least as quick as
the RV-9. Stalls seemed gentle and conventional.
Of course, it had a heavy wing – some
traditions just can’t be ignored.
It’s far too early to make any
statements about what the airplane is like or what will do, or
what the performance numbers may eventually be. We can report
that when Van taxied in and opened the swing-up canopy, he was
Grinning.
Click
here to view the RV-12 First Flight Video posted on
youtube.com
Click on any photo to view a larger
image.
Van getting
ready
Crew working with computer
Taxing out
Lift off
Click on any photo to view a larger
image.
Climb out
RV-12 aloft
RV-12 flying straight and level
Posted November 15, 2006
Ken Scott
RV-12 update
To date the RV-12
has accumulated about 2.5 hours on four flights. Both Van and Ken
Krueger have flown the airplane and both have returned pleased
with initial performance and handling qualities. They report very
little adverse yaw, with the flaperons up or down. Roll rate and
roll acceleration are good. The little Rotax is proving a very
pleasant engine to fly behind…smooth, quiet and plenty of power
for an airplane this size.
We realize that these are initial,
general impressions. We are as anxious as anyone to see just what
the RV-12 will really do. Pacific Northwest weather, however, has
had other ideas. A series of storms has pounded through Oregon,
with winds topping 60 knots in Aurora. Trees and power lines have
been falling with monotonous regularity. Not RV-12 flying weather,
so the airplane is in our hangar, waiting for better. When we have
accurate performance figures, we will publish them.
We are currently taking advantage
of the situation to install the new AFS system, designed
especially for the RV-12. We will have more on that, too, once we’ve
had a chance to fly a little more.
Posted November
17, 2006
Ken Scott
We've been taking advantage of
the poor weather to complete the instrument panel in the RV-12.
Today Rob Hickman of Advanced Flight Systems
oversaw the installation of his new unit in the RV-12 panel. When
we flipped the master switch, everything booted up and here's the
result.
Click
here to view a larger image
posted
January 12, 2007
RV-12 update
This December and January, we have been squeezing flight tests
of the RV-12 in between Pacific Northwest weather systems. The
information we are gathering will be used to refine the current
"proof-of-concept" RV-12 into the "kit-built"
RV-12.
The RV-12 has so far been successfully flown while ballasted to
its anticipated maximum gross weight of 1320 lb and to its
anticipated aft CG limit of 28% Chord. To get the RV-12 weight to
1320 lb requires the equivalent with full fuel, 50 lbs of baggage,
and two 220 lb people. The RV-12 can be loaded with full fuel, 50
lb baggage, and two 170 lb people and the CG remains forward of
the 28% chord aft limit. (If that sounds odd to you current RV
pilots, remember; in the RV-12, occupant weight moves the CG
forward and fuel weight moves CG aft.)
We are currently looking closely at the stall speed. We want to
be sure that the RV-12 is REALLY in compliance with the 45 knot
stall speed required by the LSA category.
Additionally, we are experimenting with the trailing edge
configuration of the ailerons as well as some details of the
stabilator, trying to tailor the control feel to suit our
definition of "ideal". In other words, we want it to fly
and feel like other RVs, especially the RV-9.
Along the way we’ve been fine-tuning the pitch setting of the
Sensenich ground adjustable prop in an effort to achieve a
position that allows the RV-12 to meet, but not exceed the LSA
speed limit of 120 knots CAS at sea level. We have found that in
some cruise conditions the pilot must limit the throttle to keep
the Rotax engine below the max continuous RPM limit. This setting
does result in good take-off and climb performance.
We have designed a new, stiffer, set of main landing gear which
reposition the wheels slightly. These should be installed shortly.
As our confidence builds and we gain more experience, we will
be exposing the RV-12 to more and more pilots of differing
experience levels to get a wide range of impressions and comments.
(Said pilots can’t wait!)
posted
April,
07
Our RV-12
Proof-of-Concept prototype N912VA has flown about sixty
hours now. That may not seem like a lot, but when you
consider almost all it has been in real-world flight
test, you can see that it’s had the opportunity to
teach us quite a bit.
Here’s some updates on our progress so far, with
notes on various aspects of the airplane:
ROTAX 912S ENGINE-CARE AND FEEDING THEREOF
The RV-12 is
our first experience installing, operating, and
servicing the 100 hp Rotax 912 engine. Being a liquid
cooled, high RPM, geared engine, it is quite different
than the Continental and Lycoming engines.
Installation was more challenging than a Lycoming
because the engine has two carburetors, a separate oil
tank, and two heat exchangers; the coolant radiator and
the oil cooler. On the plus side, with liquid cooled
cylinder heads, no baffles other than a shroud for the
inner fins of the cylinders are needed.
We mounted the heat exchangers vertically in the
lower forward cowl, under the spinner, and fed them air
through a single horizontal oval inlet. Mounting them to
the cowl isolates them from engine vibration and
provides an excellent seal, so no air is lost through
duct connections or relative motion between the cowl
opening and the coolers. There are also two small round
inlets near the spinner which provide air to the
carburetors and cool the inboard portion of the
cylinders. They have worked very well in keeping the
cylinder head temperatures cool.
The oil cooler has worked too well in the cool
ambient temperatures we’ve experienced testing in
autumn and winter. Rotax specifies that engine RPM
should not exceed 2500 (the Rotax idles at 1200 rpm and
red line is 5800 RPM, so 2500 rpm is still low power)
until oil temps reach 120 deg. F. This has caused long
run-up times before take-off.
Operating the Rotax is a very pleasant experience.
The Bing carbs are equipped with chokes for starting
rather than primers (older drivers will remember chokes;
they were common way back when cars had carburetors.)
They also feature automatic mixture compensation for
altitude changes, so there is no mixture control in the
cockpit. The engine starts easier than either a
carbureted or fuel injected Lycoming. It is smooth and
quiet, both on ground and in flight.
Fuel consumption is obviously lower than other RVs
because of the low power of the engine. However, despite
magazine writers like to rhapsodize about how the Rotax
"sips" fuel, its consumption (in our
experience and from Rotax charts), is consistent with
other aircraft engines of similar power. Its Specific
Fuel Consumption (bsfc) is similar to Lycoming and
Continental engines, so at rated 75% power, it burns
about 5.8 GPH. Figures like "3.5 to 4.5 gph"
are often quoted in flight reports, but these can only
be achieved by using less than 75% power and should be
noted as "economy cruise consumption" figures.
HANDLING QUALITIES
The full span
flaperons provide brisk roll control, similar in roll
rate to an RV-9. Initially, stick forces required were
very light, so we tailored the flaperon trailing edges
to provide a pleasant stick force level. During the
design phase, we worried about possible adverse yaw when
the flaperons were lowered into the flap positions.
Testing revealed that adverse yaw is minimal and easily
coordinated with light rudder pressure.
The new (to us) stabilator has proven to provide good
pitch control, pitch stick force, and damping. The RV-12
has an electric pitch trim which repositions the large
anti-servo tab on the stabilator trailing edge. The trim
rate is moderately slow, with no tendency for
over-control.
Stall characteristics are good. Tail surface
buffeting several mph above stall speed provides ample
warning. The nose pitches down when the full stall is
reached, and flight control is regained almost instantly
when stick backforce is released. In an aggravated stall
when the stick is held back through out the actual
stall, one wing or the other will drop as much as 30
degrees.
We contracted with a professional test pilot to
explore the spin characteristics of the RV-12. The
results were very encouraging. Spin entry and recovery
was found to be normal and predictable. Good rudder
control authority was found both during spin entry and
recovery. The RV-12 tail configuration, with the
vertical surfaces positioned forward of the horizontal
surfaces, provides minimal blanking of the rudder in all
conceivable pitch attitudes. Recovery from 1-turn spins
was achieved in less than ¼ turn following anti-spin
control application.
PERFORMANCE
Strange as it
may seem, we have not expended a lot of effort on
measuring the RV-12 performance. We measured enough to
realize that the performance was "good", and
then concentrated on stall speed, stability,
controllability, weight and balance, and other such
issues. Here are some basic numbers:
Cruise Speed (75% power @8,000’) 118 kts.
Climb rate: 1320 lbs. gross wt. 750 fpm
Climb rate: (solo, 1000 lbs) 1100 fpm
Stall speed: @ 1320 lbs. 50 kts
STALL SPEED
Stall speed
has been one of the tougher nuts to crack, and the focus
of much of our test flying. Initial testing showed that
the RV-12 no-flap stall speed was higher than 45 knots
required by the rules of the Light Sport category.
We experimented fairly extensively with corrective
measures. We tried vortex generators in many
configurations and placements. We even made full-span
leading edge cuffs that increased the camber of the
wing. Neither improved the stall speed -- and just to
make things more frustrating, the cuffs actually reduced
the cruise speed.
Airflow tuft testing of the airframe showed
undesirable flow under some conditions at the wing
root/fuselage intersection -- not unusual for low wing
airplanes. We devoted considerable time and effort
installing and testing various wing root filets in an
attempt to improve lift in this region and thus lower
stall speed. The airflow was improved somewhat, but
there was no measurable improvement in stall speed.
IN THE (NEAR) FUTURE:
Work is
underway to design and build a new KIT PROTOTYPE
airframe (as opposed to the PROOF OF CONCEPT PROTOTYPE
described above).
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It will have an improved wing with a different
airfoil and more area.
-
We found we could improve the CG by moving the
engine forward. At least two good things came out of
this: improved access to the back of the engine and
about 2 more inches of legroom in the cabin.
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The canopy on N912VA has never been a beauty
point. It was built with some plexiglass canopy
halves left over from an earlier project. The kit
prototype will feature a much more attractive
1-piece blown canopy with additional headroom,
designed specifically for the RV-12.
WHEN?
Our best
projection is that the new Kit Prototype RV-12 should be
ready to fly late in the third quarter of 2007. Kit
availability will depend upon the test flight findings
of that aircraft and on our ability to initiate
component production both in-house and from our
suppliers. We hope to have at least partial kits
available in the fourth quarter of 2007 or the first
quarter of 2008.
posted
June
19,
07
Here are some
new photos of our RV-12 Proof-of-Concept aircraft.
N912VA looks good with it's yellow paint and black vinyl trim.
The canopy
remains unpainted because we soon will be replacing the
prototype canopy with a more attractive pre-production version.
Click on any photo to view a larger image.
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