dashvii(at)hotmail.com
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 Posted: Mon Aug 21, 2006 11:13 pm Post subject: Lightning Pilot Report Repost |
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Ok, I'll bite. I've got several hours in the Lightning now. Hopefully this
won't bore all of you and I'll try not to be too technical. Let me start
with a little history on the Lightning. The Lightning was developed around
the same idea as the Esqual, a light, fast, fun, and affordable sport plane.
The Vol Medici company that marketed the Esqual sold off the company and
(so far) stop producing the Esqual kits. Jabiru USA was the US importer for
Esqual. This aircraft complemented the Jabiru line of aircraft as well as
providing for a low wing alternative to the high wing Jabirus.
The wing of the Lightning was designed much like the pressure recovery
wheelpants. The wheelpants are from the RV series of aircraft and modified
to suit our own needs. RV borrowed the design from Cessna. The idea is
that there was a better way to fair the landing gear that would result in
less drag. At the point where the airflow starts to detach from the surface
of the gear, the shape would create a suction that would reattach the
boundry layer. The wing was designed as a kind of teardrop shape with
concave trailing edge shape. It is a high laminar flow wing.
Now the wing that is on the Lightning is kind of a reverse engineered wing
that was originally on the Esqual wing. For various reasons that airfoil
was traded for a different one and the molds were destroyed. The new Esqual
wing is more of a Clark Y "Hershey Bar" type. That wing will allow for a
shorter takeoff run, but at the same time will float forever if you come in
hot and get in ground effect. In Europe, operating out of grass strips the
lower takeoff run and slower liftoff speeds were more desirable on a sport
plane than all out speed. The Lightning wing is whole different beast. The
speeds are higher on the plane for takeoff and landing. The flaps work much
better than the Esqual in that they provide the needed drag where the Esqual
is mostly lift and a means of not accelerating when pointing the nose down,
kind of more like a speed brake. As with any glass plane it will accelerate
rapidly when the nose is pointed down in a clean configuration. On one
particular flight test in an Esqual I tested for aileron flutter after
finding and tightning a loose aileron. With the power to idle in almost a
vertical down line the Esqual will quit accelerating and hold about 185-195
mph indicated. The Lightning will eagerly pass through 200 and rapidly
accelerate past Vne.
There were two "hybrids" and one prototype aircraft. The first hybrid,
which we refer to as the "Frankensqual" is an Esqual fuselage with the
prototype set of Lightning wings. It has an old 80hp Jabiru 2200 engine and
will do 160mph flat out! The airplane is about twice as pitch sensitive as
the Lightning with much lighter feeling on the controls. It has a far aft
CG because of the light weight of the engine and had each wing that was
60lbs. heavier. Very impressive performance and after about 15 minutes of
flying it you get used to the sensitivity. The next was Buzz's plane which
tested the wheelpants, gear leg fairings, and the cowling for the lightning.
Buzz built the fastest Esqual in the world, by about 40-50mph! In fact,
his plane is similar in performance to the Lightning. In an all out speed
comparison at 5,000 feet the prototype Lightning pulled away from Buzzes
plane by about 1-2 knots. The pitch of the prop wasn't set to the optimal
level on the prototype at the time in its defense. Some of the speed can
certainly be attributed to Buzzes craftmanship and attention to detail. For
those of you who have seen it you know what I mean. Getting everything
faired over and making sure that you have a tight fit and smooth finish
amounts to drag reduction, and superb looks. Buzz also got custom leather
interior and foam fitted seats put in. I encourage any of you builders to
do something similar. The cloth seats are comfortable, but those
leather/foam seats just really feel nice and make for a comfortable ride.
The prototype, as did Greg Hobbs' plane had a thicker tail section which was
the result of a miscommunication. The fiberglass layups were extremely
thick in the tail which resulted in a much heavier fuselage with an aft CG.
While this is great for speed, it is horrible for loading arrangements and
total useful load. All of the newer planes have a lighter fuselage which
should mean better takeoff performance and acceleration. The prototype also
had an early horizontal stabilizer that was (I think) 6lbs heavier per side.
It has since been replaced with a production tail. Nick is continually
finding little ways to improve performance, looks, functionality, etc. This
is as much his baby as anybody's and he continually tweaks things. The
prototype eventually got to a little over 200mph TAS in level flight. That
was at greater than 3300 rpm though.
Now on to the Pilot Report:
First off, approaching the airplane you notice that it is a very nice
looking plane. The complex curves of the composite aircraft look very
similar to that of a Lancair or Cirrus. The plane is smaller than either
and looks fast just sitting there. A walk around is similar to any other
light airplane with attention to the composites. I like to get down to eye
level with the surface and look for any chips or cracks that may indicate
delamination. So far I've never found any, which is the way it should be
for a newly built plane, but it is a different type of a thing than you look
for in a metal airplane. I pay careful attention to the tail area and
stabilizers. The wings are extremely strong and both main wing spars cross
through the fuselage, under the seat. The rear of the wing attaches to the
fuselage without a carry through structure.
Getting in the airplane is accomplished by climbing up on the wing, being
careful to avoid stepping on the flaps. The sides of the plane are fairly
low and you can easily throw a leg over into the cockpit. At this point you
want to step into the seat and then your other leg goes over and into the
floorboard. Once seated you find that there is adequate room for two adults
to fit comfortably, even for long trips. The center console does get in the
way, keeping you from moving the stick to the stops because it hits your
knees. Future planes will have a console that terminates at the edge of the
seat. This should fix the problem. Sitting in the plane the seats are
reclined a bit. I find that on a long trip this made me want to raise my
head forward and that was uncomfortable after a while. If the plane is
going to be used for some long trips I would suggest fasioning some type of
head rests. This of course would limit the useful load some though. The
visibility is incredible with that bubble canopy. The canopy itself is much
clearer and free of distortion when compared to the Esqual. Another thing
is that the Lightning has a longer nose and gives a difference perspective
than flying in an Esqual.
With two on board and 10 degrees of flaps the plane will Flying Greg's
airplane I found that the airplane was very responsive. The airplane will
rotate the nosewheel to a degree or so at about 50 mph and will hop into the
air at a little less than 60mph. Once airborne a speed of 80mph will give
you greater than 1000 feet per mintue climb. The airplane is nimble, about
90 degrees of rolls per second. It has a really nice feel to it. The
pushrods give a direct feedback from the plane and have a firm, but not
heavy feel. This gives the plane a sporty feel, but not a twitchy overly
sensitive feel. In a climb with high RPM and low speeds the plane requires
some good rudder input. Again the controls are firm, but not heavy. Greg's
airplane had a trim control issue at first which caused us to run out of
trim and the nose would still fall at certain speeds. The plane can be
flown in all operating configurations without trim, but it is more
comfortable and easy to fly with the use of trim. The plane can be flown
hands off when in unaccelerated steady-state flight in trimmed
configuration. Again, on a long trip a dual axis autopilot would be nice to
have, especially when coupled with the Grand Rapids EFIS. That would even
do virtual approaches on autopilot.
Landing speeds seemed to fall right in place if you can enter the pattern at
no more than 110mph and slow to around 100 on downwind. The plane flies a
nice at the 65mph final approach speed. The plane seems to have good rudder
control and excellent aileron control authority in these lower speed ranges
as well. Landing is more challenging in some ways than the Esqual. The
Lightning doesn't really float. It is similar to a high performance Mooney
in that the laminar flow wing flies to a point and then it stops. The trick
is to round out the flare with a slight nose high attitude just as you reach
the stall speed of between 45-55mph depending on configuration. I liked
using 20 degrees of flaps instead of 30 degrees. For me it seemed to give a
flatter and better feel on the approach. 30 degrees of flaps led to a good
decent angle and although the plane will land just as smooth, I felt that
this wing wanted to fly onto the runway.
Flying Greg's plane out to the Tucson area we covered around 500 miles in a
little over 2.7 hours. We burned approximately 6.0 gph at 2950 RPM
(slightly high side of cruise RPM) Greg admitted that the jets weren't
quiet tweaked as well as they could be and that a slightly lower fuel burn
would be in the near future for his plane. We also didn't have the plane
all fastened up and as sleek as it could be. The plane still had a slight
right roll which resulted in about an inch of each aileron being deflected
and causing undue drag. Greg had planned on fairing over some small parts
around the wheelpants and gear leg intersections. We had hotter than normal
CHT's due to an 'experiment' with adding a ramp to one side of the cylinder
heads at the entrance. This proved to actually make the majority of the air
go over the cylinders at any angle of attack and out the outflow. I
understand that with the ramp removed the CHT's are more uniform now. With
these little improvements that Greg has done I imagine he'll pick up another
10 knots or so at least.
There had been the thought of testing some gap seals on the prototype to get
some additional speed for free type of an improvement. I had also suggested
a winglet design for cruise performance, looks, and the added stability for
long cruise flights. If correctly designed they would slightly increase
speed, increase range and climb rates, decrease takeoff roll, but I believe
the looks are worth as much if not more than the performance gains.
If any of you know Greg or if he is part of the list, tell him that I'd be
happy to make the journey out west to fly any of the customer planes on some
of the first flights. They all are a little bit different and all have
their own special needs as far as setting them up. Once you get things
right though you get a "Lightning" fast airplane that is comfortable and
stable. Hope you all enjoyed the read and any little improvements to the
plane that you want to suggest I'll be sure to relay to Nick.
Brian Whittingham
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