|
Specs:
- Wingspan: 79 in (2007 mm)
- Wing Area: 1096 sq in (70.7 sq dm)
- Weight (glow): 8-8.75 lb (3600-3940 g) as a glow model.
- Weight (electric): 10.5 - 12.5 lbs. (4725-5625 g)
- Weight (as reviewed): 12.5 lbs (5625 g)
- Wing Loading (glow): 16.8-18.4 oz/sq ft (51-56 g/sq dm)
- Wing Loading (electric): 22.1-26.3 oz/sq ft (66-79 g/sq dm)
- Length: 54.5 in (1385 mm)
- Recommended Power (glow): 2-stroke .61-.75 cu in (10-12 cc) or 4-stroke .70-.91
cu in (11.5-15 cc) engine
- Recommended Power (electric): 28 to 36 cell power system
- Power System (as reviewed): 36 cell, RC2000, Aveox 1415/3Y motor, ModelAirTech
H-1500 belt drive (3:1 ratio), MaxCim 36-cell ESC,
Zinger 14x8.
- Available From: Great Planes - www.greatplanes.com
|
Introduction
I have always enjoyed building my own models and have never felt particularly
interested in Almost Ready to Fly (ARF) kits. However, I couldn’t help but find
myself excited by the Great Planes Spacewalker ARF, which I saw for the first time at a
local hobby shop. Here was a very lightweight, mostly built, IMAA and IMAC legal airplane
that would be a great way to test out the power system I had set aside for another, more
ambitious project.
Kit Contents
The kit is very complete and includes everything you will need except for the radio and
electric power system. The aircraft is built from balsa, plywood, and light ply and is
nicely covered in red and yellow monokote. The cowl and wheel pants are plastic, but the
cowl is reinforced with fiberglass strips and seems strong enough to survive several
seasons of flying.
I found no need to replace any of the included parts when constructing my kit, except
for the motor mount which would not work with my choice of power systems. All the included
hardware is of suitable quality. The only odd thing about the kit is that it comes with
something called a "fuel tank". This strange device was set aside. What purpose
it serves, I may never know.
Construction
There is very little building involved with this ARF model. I managed to build my kit
in a handful of evenings, including the time taken to figure out how to install the
batteries and other electric components.
The Wing
The wing is handsomely covered in a yellow and red sunburst pattern. Finishing the wing
is a simple process. Notice that Great Planes did you a favor by taping down a piece of
string inside the aileron servo cut-out. This makes it trivial to install aileron servo
extension wires. A nice touch!
Join the wing using epoxy. My plywood wing joiner did not fit until I sanded it down a
bit. Make sure it fits smoothly before putting any glue on the joiner.
No IMAA-legal model would be complete without aileron servos sticking out of the
bottom of the wing!
|
After the wing is joined, you can install the ailerons. Though it may
not look like it at first, the ailerons are not exactly the same. Each aileron has a
hardwood block underneath the covering, which will be used as a mount for the control
horn. This is an easy detail to miss. Double check that you have the ailerons matched with
their respective wing halves before hinging.
The Fuselage
The horizontal and vertical tail pieces are precovered and surprisingly lightweight for
their size. Installing them is as simple as cutting away part of the covering and gluing
the tail pieces into the slots you’ll find underneath the skin.
As you can see in this photo, the tail is of lightweight, built-up construction.
|
The Spacewalker uses a dual-pushrod arrangement for the elevator, rather
than connecting the elevator pieces together via a wire or dowel. Bending and
finishing the pushrods is a task left up to the modeler.
Equipment
With many conversion projects it can be difficult to find room for the equipment due to
the space taken up by the battery. The Great Planes Spacewalker ARF, on the other hand,
provides a cavernous fuselage with plenty of room for everything.
36 cells? No problem. Plenty of room for all of your equipment.
The battery consists of two 8 cell packs and two 10 cell packs. For the plane to
balance at the correct point, the packs had to be situated very close to the firewall, but
not quite touching.
I chose to use high-torque, metal-geared servos for the elevator and rudder.
Do not try to skimp on servos when building a large plane. Even a fairly
docile airplane like the Spacewalker deserves meaty servos.
|
Power system selection is an issue that has been dealt with in many
articles, so I won’t go into great detail on how I chose my system. The Spacewalker
ARF will fly well on nearly any ¼ scale electric power system from 28 to 36 cells. A
lightweight motor/gearbox combination and 28 cells will yield a finished plane that will
fly (and weigh) much like the glow version. My plane, with 36 cells, an Aveox 1415/3Y, and
a ModelAir-Tech H-1500 belt drive, comes in at
12.5 pounds. This is three pounds heavier than the glow version, but the performance is
excellent. This power system is roughly equivalent to a 1.20 sized glow engine.
This picture is taken with the cowl removed and the fuselage upside-down, to show
off the motor and the speed control. The H-1500 belt drive has a beefy, industrial
look to it and has proven itself to be capable of handling 1300 watts.
|
I chose to use the MaxCim Maxu35-36
ESC in my model. Tom Cimato, of MaxCim, is now selling versions of his controllers to work
with Aveox motors. MaxCim
makes fine controllers and this seemed like an excellent chance to test one of these new
units out.
The Conversion
Converting this model is child’s play. I had to toss out the supplied motor mount
because the H-1500 belt drive needed just a bit wider mount. I found one at the hobby shop
that worked perfectly. The electric motor system fits into the mount just like a glow
engine. I drilled holes in the firewall and used cable-ties to secure the ESC to the
firewall. I then cut several large holes in the firewall and a sizable hole in the balsa
floor of the canopy so that cooling air could flow in through the holes in the cowl, past
the electronics, into the fuselage/battery compartment, and out the canopy area.
Jim's Nifty "Connector Jack"
I hate the added complexity of a charging jack, but I don't want to be
forced to remove the wing to charge my planes. I want to bring several planes to the
flying field, assemble them, and then charge and fly without having to take anything apart
or going through any other hassles.
Over the years, I've tried many different approaches. I've made charging
jacks in some airplanes, made some models with quick release hatches, and even once or
twice I've velcroed the packs to the outside of planes. All of these tricks work,
but I've found an even easier solution for those of us who use Anderson-style connectors.
Ever noticed how the Anderson connectors, when joined, have a nice
mounting hole? Take advantage of that hole by passing the ESC lead out of the plane
and screwing it down on the bottom of the fuselage (or even the side if you aren't worried
about looks). Now cut a hole for the battery lead and pass the connector out the
hole.
Now all you have to do is plug in the connectors when you want to fly and
unplug the connectors when you want to charge. This effectively gives you both a
charging jack and an on/off switch, and is a great convenience for models that do not
require a scale finish.
A close-up of my "connector jack".
|
The battery pack fits in the fuselage easily. I simply had to use a dremel tool to
remove about ½ inch of the second fuselage former. My 36 cell battery consists of two 8
cell and two 10 cell packs, which are held in place using cable ties and velcro.
Everything fits so perfectly, it seems almost like the Spacewalker ARF is made for
electric power.
A lightning bolt sticker, from one of my daughter's Humungous Entertainment computer games, adds a nice
touch to this electrified model.
|
The power system I’ve chosen turns a Zinger 14x8 propeller at about
10,000 RPM right off the charge. This tapers off to somewhere around 9500 RPM during most
of the flight as the batteries lose their initial surge within 30 seconds or so. This
propeller draws roughly 35 amps at full throttle on a fresh charge.
Flying
The test flight was performed on a very windy day, but the winds were coming straight
down the runway so there was no reason not to fly the airplane. With 100 watts/pound, I
had no doubt that the plane would have plenty of power and its large size made me
confident that the wind would not cause any problems.
I taxied the airplane out to the center of the runway and did a few last minute checks
to make sure everything was secure. I decided to ease the throttle up slowly, but to my
surprise the Spacewalker decided to become airborne by the time I had reached half
throttle. The first flight was flown without once putting the throttle above the
3/4ths mark, yet still included a few loops and nice, tall stall turns.
After testing out the airplane thoroughly I’ve found that it is quite capable
aerobatically, but is still very easy to fly and land. I have not timed my flights yet
because I find myself flying until I am simply ready to quit. Based on experience, I can
predict that this plane will yield very enjoyable 8 to 10 minute flights. At full
throttle, the duration would only be 4 minutes or so, but full throttle flight with the
power system I’ve chosen would be so un-Spacewalker-like that I have little use for
trying that out.
First flight sans cowl, to facilitate tweaking of equipment. Tweaking proved
unnecessary as all components worked flawlessly.
What's that red thing on my shirt? Why its "Bob the
Tomato", from Veggie Tales. |
The next step in enjoying this plane was to take it to a giant scale
fly-in and see how well it fit in. It seemed that no one at the fly-in had ever seen a
large scale electric airplane before. As I walked out to the flight line, the announcer
came on and told everyone that an electric airplane was going to fly. It became eerily
quiet as everyone on the field immediately stopped what they were doing so they could
listen to the sound of the yellow and red Spacewalker as it performed graceful aerobatics.
After landing, many pilots came up and asked questions.
I found that the electric-powered Spacewalker fit in quite well with the other models
at the meet. It did not appear underpowered in any way. If you are looking for a way to
enjoy IMAA fly-ins but do not want to build your own giant scale airplane from scratch,
the Great Planes Spacewalker ARF is a good choice.
Recommendation
The Great Planes Spacewalker ARF is ideally suited to electric flyers who are looking
to try out giant scale without spending a lot of time building. The Spacewalker ARF is a
very lightweight airplane right out of the box and requires very little modification to
convert it to electric.
I’ve often thought of ARF models as overbuilt, but even if I started from scratch
I could probably only shave half a pound or so from the airplane. Great Planes has done a
fantastic job of keeping the airframe light. The fuselage, in particular, is well designed
and of the lightest possible construction. Any extra weight on the airframe is probably in
the wing, which seems a bit heavier than it needs to be, but only by a few ounces. The
nicest thing is that Great Planes has done all the hard work for you! If you have a
tight schedule, or if you simply don't like to build, this is a great way to start flying
the big stuff.
I needed a suitable pilot figure and finally decided to go with Wallace, a
character from an Academy Award winning series of claymation short films. Check out
Wallace on the web at www.aardman.com.
|
One thing I’ve learned from the Spacewalker is how much fun giant
scale can be. Truly, nothing flies quite like a large model. The Spacewalker looks much
more realistic and stately in the air than a small model ever could. However, large models
are not for everyone. There is a very real effort involved in transporting a large model
and the storage concerns cannot be overlooked either. But, having made the commitment,
I’ve found giant scale to be very rewarding.
I life a pretty hectic lifestyle that involves a lot of business travel and very little
free time. To me, a quality ARF like the Spacewalker is a godsend, as it allows me to
enjoy the hobby without feeling hurried on the other projects I’m working on. To
some, an almost ready-to-fly model might even make the difference between being in the
hobby or being unable to participate at all. Either way, the Spacewalker gets a big
"thumbs-up" for being a quality product that assembles quickly and flies well.
Apr 01, 2009, 12:53 AM
Similar Threads
