Distributed
exclusively by: AirBorne
Models, LLC
2403 Research Drive,
Livermore, CA 94550
USA
Support Phone:
Tel: 925-371-0922
Fax: 925-371-0923
sales@airborne-models.com
The
P-47 Thunderbolt is one of the most recognizable designs from
World War II, and the first in a line of successful, if not legendary,
“thunder” designs from Republic Aircraft. Larger,
heavier, and more powerful than any single-engined fighter of
WWII, the P-47 isn't the most maneuverable plane in full scale,
but it is one of the fastest. In wartime conditions, the P-47
is famous for its ability to take punishment, and became a legendary
ground-attack aircraft.
Fast
forward to today, and the P-47 is one of the most popular warbirds
of all time in model form. While there are literally dozens of
different P-47 models ranging from plastic static models up through
giant scale radio control models, there hasn't been a handy park
flyer version, let alone one with functioning retracts.
Kit
Name:
P-47D Thunderbolt EP Price: $119.99
retail price Wingspan: 39.5" Wing Area: 282
sq. in. Flying Weight as tested: 32oz. Airfoil: Semi-symmetrical Motor: KM0283010
Outrunner Battery used: 3s
2200mAh JustGoFly ESC used: 30A JustGoFly Radio equipment: Spektrum
DX6i, AR500 receiver, Tower Pro 9g servos
Square
Hobby Knife
Ruler
Small Phillips screwdriver
1/16 drill bit
Pliers
Medium CA
30-minute epoxy
Masking tape
Every
project starts out with a plane in a box.
This
is what came in the box. It's a very complete kit, including all
the hardware.
The
motor mount is designed to fit Airborne's recommended KM0283010
outrunner.
When
you think of color schemes for a P-47, two colors come to mind: Olive
Drab, and Natural Aluminum. Earlier models were painted olive drab to
provide a bit of camouflage over the forests and fields of the European
theatre. As the Allies gained air superiority over the Axis, newer planes
were painted only with squadron markings to save money and weight.
How
does it come to be, then, that the legendary “Jug” ends
up as a model kit in metallic blue and silver? I don't know, but I like
it! First and foremost, it's different. Every other P-47 on the market
is in typical olive drab and/or natural aluminum and black.
The
plane's markings closely resemble an actual full-scale P-47D model that
flew with the 86th
Figher
Group in World War II, but they're done using the metallic blue anywhere
you'd expect black. All the scale panel lines and rivets are printed
right on the LightTex covering in the metallic blue on a metallic silver
background, which makes them very noticeable from a short distance away.
This may be the reason for the color choice; the blue “pops”
out at you and really shows off the detail.
Pre-trimmed
belly pan with nice wide gluing tabs.
The
canopy has predrilled mounting holes! This is going to be fun.
Fuselage
is all laser-cut balsa and ply, and the covering job is excellent.
The
center of the stab is already stripped of its covering, ready
to glue!
A
striped tail, just like the prototype 88.
Woah!
That is one scary looking guy. I'll have to think about this for
a while...
Retract
Trigonometry 101
To make mechanical retracts work
reliably, the servo needs to be set up to move the retract
pushrod far enough in both directions. If the kit manufacturer
doesn't give you the distance, it's easy enough to measure.
Achieving the right amount of throw
can be tricky. Key is installing the EZ connector the correct
distance from the center of the servo. Here's how you figure
out that distance:
A regular servo moves through 90
degrees full travel. This sets up a perfect 45-45-90 triangle,
shown in blue on the diagram.
With a 90 degree triangle, the
lengths of the sides relate to each other using the formula
A2 x B2 = C2, labeled in
red on the diagram. C turns out to be the distance the pushrod
needs to travel to move the retract from locked up to locked
down as the servo arm rotates through its 90 degree travel.
Because this is a 45-45-90 triangle, A and B are the same
length, AND they tell you where to put the hole for the
EZ connector!
Rather than get into all the boring
math, it turns out that if you divide the pushrod travel,
C, by 1.414, you now know where to locate the hole for the
EZ connector!
For the P-47, the instructions
call for 16mm of travel for the retract pushrod. Using the
formula, it turns out that the EZ connectors need to be
located 11.3mm from the center!
Installing
the retract servo in its recommended location. Turned out
to be too far to the left.
All
the linkage hooked up. Notice that I had to move the servo,
and clearance the sheeting so the servo horn could rotate.
Setting
up mechanical retracts can be tricky and frustrating. Getting
both gear legs to lock up and lock down securely, and at the same
time, has caused the recession of many a hairline.
The
retracts pre-installed in the P-47's wing have a quality feel
to them. All the pivots are very tight and move smootly. Lock-up
and lock-down are very positive, with minimal gear wiggle in either
position.
Starting
with quality retract units makes the job much, much easier. These
retracts also utilize a standard servo instead of a retract servo,
which turns out to be another advantage. Standard servos rotate
90 degrees normally, and have adjustable travel, while retract
servos rotate through 180 degrees, period. Here's how to do it:
Install
the servo in the wing.
Make
sure the retract channel is set to 0 trim, 0 subtrim, 100%
ATV. Connect the servo to the retract channel, and put the
switch in the raise position.
Find
a two-arm servo horn with holes approximately 11.3mm from
the center (see Retract Trigonometry 101 inset to see how
I figured this out), and install two of the included EZ connectors.
Install
the servo horn on the servo at an angle as close to 45 degrees
as possible (see photo). Flipping the arm end-for-end will
get you a different angle if you can't get close on your first
try. Use subtrim to get the perfect 45 degree angle.
Cycle
the retract switch, and if the arm moves in the wrong direction,
remove it, turn 90 degrees, and reinstall. Readjust the subtrim
for that perfect 45 degree angle.
Install
the retract pushrods into the EZ connectors. You may want
to disconnect power to the servo so you can move things around
and get the pushrods installed.
The
servo will be either in full-up or full-down position when
you reapply power. Move the retracts into the appropriate
full-up or full-down position and tighten down the EZ connectors.
Cycle
the retracts. Adjust the ATV on your transmitter until the
retracts lock both up and down without the servo buzzing.
I
know, it seems complicated, but the alternative is hours of trial
and error. It'll be a bit trickier without the benefit of a computer
radio, but the process will be essentially the same.
Three
different mounting lugs cover most 9g-class servos
The
lugs plug into the aileron servo hatch like legos.
It
took the shortest lugs to accommodate these Tower Pro 9g
servos.
A
string is looped through the wing from aileron bay to aileron
bay to facilitate easy servo installation.
Pre-bent
pushrods are exactly the right length.
Same
song, second wing.
The
one-piece wing (No epoxy; gotta love it!) means that wing preparation
is minimal. Once again the prefabrication of this ARF really shines,
with modular aileron servo hatches. Airborne has developed a hatch
system that they use on many models in their EP series that consists
of the plastic hatch cover and three different sets of mounting
lugs for the aileron servos. Each set of lugs is a different height,
allowing many different types of “9 gram” servos to
be installed with the servo arm centered in the slot. Using the
TowerPro 9g servos, I needed the shortest lugs.
Threading
the aileron wires through the wings was a snap using the string
in the wing. With the hatches secured in place, it's a snap to
hook up the aileron pushrods because they're pre-bent and cut
to the correct length. I added short pieces of medium silicone
fuel tubing, from the hobby shop, to the clevises to hold them
securely closed.
With
the tail surfaces pre-stripped for installation, it's epoxy-mixing
time.
Looks
a little naked, but it's coming along nicely, and quickly.
This
aileron joiner is unique, with an integrated control horn.
Elevator
assembly is quick and painless.
Rudder
installation is pretty typical.
Same
goes for the elevator, except it's ready to, um, elevate
I guess...
Tail
preparation is straightforward. The slots for the fin and stabilizer
were almost dead-on, requiring no adjustments to achieve a square
tail.
While
the epoxy dried, I set about assembling the elevator. Normally
the two elevator halves are connected with a hardwood dowel or
a piece of wire. Airborne uses a unique approach to this with
a custom-molded elevator joiner that integrates a control horn.
Each elevator half slides into a slot, and is clamped in place
with a bolt. What I did notice here was that the elevator halves
are a little thin for the slots, so I slid a thin bit of cardboard
in to make up the difference. With the bolts tightened down, the
assembly was very rigid and secure.
Just
like the aileron pushrods, the elevator and rudder pushrods are
cut to length and pre-bent. It didn't take long to get the control
surfaces CA'd in place, with both control horns and pushrods connected.
Two
TowerPro 9g servos provide the motive power for the tail
surfaces.
More
of the radio gear is in place.
It's
not a scale tailwheel, but it's strong, light, and simple
to install.
Time
to get busy with the business end with the motor, motor
mount and a large pile of small hardware.
Motor's
mounted, and the bullet connectors are soldered on the motor
and JustGoFly ESC.
Attaching
the motor to the airframe is a matter of four socket head
cap screws.
It
doesn't take much effort to locate the cowl. Simply line
up the paint, and thread small wood screws in through the
predrilled holes.
The
folding prop is unusual for this type of model, but what
can I say? It works!
Four
predrilled holes in the canopy make locating and securing
the canopy painless.
One
more part left to install, but I just couldn't wait to see
what it looked like with the wing attached.
With
the belly pan installed, the plane is ready to fly.
Once
the tail is finished, the rest of the assembly goes QUICK. The
level of prefabrication on this plane is truly impressive. Everything
that needs locating has holes already drilled. It's a simple matter
of lining up the holes and threading in the appropriate bolts
or screws.
An
interesting feature of this plane is the folding propeller. It's
definitely a non-scale feature, and something you normally see
on sailplanes, not on radial-engined warbirds.
I
just couldn't bring myself to install the pilot that was included
with the kit. Scale pilots are just not my thing, and quite frankly,
they freak me out a little :)
The
final step in assembly was installing the belly pan. After the
wing is attached and aligned, the belly pan is simply glued to
the bottom of the wing. It's not structural, so there's no need
to strip the covering from the wing where the pan makes contact.
I simply placed a small dot of medium CA every 1/2” down
each mounting flange, and held the belly pan in place until it
set in place.
The
included decal sheet includes this familiar cottontail.
Even
at a distance, the scale detail stands out due to the color
selection.
The
P-47D's squadron number 88 prominently displayed.
The
battery hatch blends right in. It's located directly behind
the cowl.
JustGoFly
batteries use Sabin cells, rated for 25C. After dozens of
flights, they're easily outperforming the budget-priced
packs.
Even
perched on a starting stand, the P-47 looks imposing.
So, how does it fly? In short, it flies GREAT!
Before I attempt to fly any plane, I do a
completely unscientific full-throttle pull test. It's one
of those things that you can just “feel.” You
know if the plane is going to go or not. When that big 11”
folding prop spooled up, I knew this little P-47 wasn't
going to have any problem.
If a plane has landing gear, I always like
to at least attempt to take off from the ground. The field
had just been mowed, but it was getting on into the evening
and the grass was getting sticky from the settling dew.
That grass grabbed on to the little wheels like Velcro and
held the plane fast when I goosed the throttle, causing
a nose-over and prop strike.
A quick inspection of the plane yielded no
signs of damage, so I tried again. This time I was able
to feather the throttle and get the plane rolling. From
there it was only a short scoot across the grass before
the P-47 broke ground and climbed out.
Long story short, that is the only shortcoming
of Airborne's P-47. If you want to use the landing gear,
the runway must be a hard surface, or extremely short, dry
grass. I've resorted to hand launching and belly landing
with the gear up. This isn't as much fun as scale takeoffs
and landings, but it's a lot easier on the plane.
Beyond that, I could find little fault with
the flying qualities. This scale P-47 really shines when
being flown in a scale fashion, but it has excellent sport
plane and aerobatic capabilities too.
Once the plane was trimmed out and flying
straight, I made a few laps around the field to get acquainted
with the plane. LiPoly batteries can vary greatly from brand
to brand, but the Sabin cells in the 3S 2200 pack I got
from JustGoFly.com carry plenty of punch to cruise at a
bit more than half throttle.
Full throttle speed is significantly faster
than cruise, but not so fast that the plane became uncomfortable
to fly, or looked ridiculously out of scale. Axial rolls
need only a touch of rudder correction, but a P-47 is meant
to do runway-length victory rolls! Not to worry, it excells
at those too, along with all the basics.
Flipping the high rate switch on flips the
scale switch off. The little P-47 will do any sport plane
aerobatics you ask it to do. Vertical is good for 300 feet
of altitude before it runs out of steam, but add in full
rudder, and the plane kicks over into a perfect stall turn.
I had my timer set for 6 minutes, and before
I knew it, the alarm was beeping. With plenty of power left,
I made several approaches just to get a feel for the slow
speed handling. There was nothing to worry about; the P-47
is rock solid right down to stall speed. Of course, I tried
to land gear-down the first time out, and of course, it
caught in the grass and flipped over. Subsequent landings
have been gear-up, and uneventful.
If anything, the power system is underutilized.
Whether I fly the P-47 scale, or tear a few new holes in
the sky, the batteries always come out cool as a cucumber.
Since the plane really doesn't need it, I haven't tried
any different props to see what happens.
Of
all the planes I've flown this summer, I've flown the Airborne
Models P-47D the most, even ignoring the short time I've
owned it.. I've literally flown it dozens of times, which
for me, is some sort of record. I only get so many flying
hours in a summer and normally I like to fly as many different
planes as possible. This one got more than its fair share
of attention, and it's easy to see why: It's a handy size,
uses inexpensive common packs, flies well, and looks good.
The
World Models Distributed
exclusively by: AirBorne Models, LLC
2403 Research Drive,
Livermore, CA 94550
USA
Support Phone: (925) 371-0922
email: sales@airborne-models.com
Website: www.airborne-models.com
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The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.
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