• Wing Span: 79.0 in (201 cm)
• Wing Area: 1096 sq in (7071 cm²)
• Length: 54.5 in (138 cm)
• Weight: 8.8 lbs (4.0 kg)
• Engine: .61 - .75 2 - cycle
  (10.0 - 12.0cc 2 - cycle)
  .70 - .91 4 - cycle
  (11.5 - 15.0 cc 4 - cycle)
• 5 Servos required

All parts in the kit were bagged and secured with cardboard dividers. A wire control rod had gotten between a wing and the box top and dented the wing. The initial impression was "Wow, they got this right". Construction looked strong and light and many details looked well thought out such as built-in right thrust. The glue used for the general construction looked like an epoxy type that is thick enough to make a small fillet in the corners. It felt harder than the hot-melt stuff. The glue joints looked very good.

The Monokote was pretty well done. There were overlapping pieces in the red trim with slight misalignments, and the over whole plane, the covering was saggy and wrinkled. Overall, the job is satisfactory but less than what would be expected from Great Planes.

All parts were present including a pair of foam tires and Great Planes rubber tires. The wire main gear and both sets of wheels were 4mm, a bit larger than 5/32". The main gear appeared to have welded joints and to be plated with a shiny, slightly dark finish. The kit came with two fuel tanks; a Great Planes 14 ounce unit and one marked "Xing Yu 420cc". It was assumed the Great Planes tank was added after problems with the other. There is a large bag of good quality hardware. The pushrods seemed a bit on the lightweight side with 2-56 wire and 3/8" wood. A nice adjustable Great Planes engine mount was included. The molded parts looked pretty good although the cowl was really thin. The glass weave was easily seen in the cowl surface texture. The wing tips were thin plastic and looked fragile. The 24-page instruction manual is complete and accurate, well illustrated and easily understood. There are no transfers or decals included. An instrument panel with decal would have been nice a nice addition.

First the Monokote was tightened nicely with iron and heat gun. About an hour each was spent on fuselage and wing. The tail surfaces were pricked with a pin to allow the Monokote to shrink down without ballooning. Missile Red Monokote was used to add trim to the fin and stabilizer, which dressed up the plane nicely. The only paint required was on the inside surfaces of the cockpit.

The instructions were followed to join the wings, add the bolt plate, and mount the wings to the fuselage. Due to a tip in the R/C Modeler review, balancing the plane laterally was postponed until the final step then the molded wingtips were installed. The wing bolts were ground to more of a point to ease their centering into the threaded nylon blocks. Measurement showed one wingtip about 1/8" forward of the other, and it was determined that this would be acceptable. At this point, all hinge slots were enlarged. Next the tail surfaces were installed. The saddle for the stabilizer needed a bit of sanding to level it with the wing, and the fin slot was opened on one side to align it with the centerline. Titebond was used for all structural joints. Cub Yellow Monokote was used to seal all the joints at the tail.

A total of 15 hinges were required, 3 for each flight surface. The instructions did not say how large to cut them from the 2" X 9" piece of CA-type hinge material provided. The Great Planes online technical help department responded almost immediately to the question saying to make them 3/4" X 1". Instead, the entire sheet was used to make 16 hinges at 1 1/8" X 1". They were installed with the long dimension parallel to the hinge line.

A Sullivan #860 tailwheel unit was installed for its shock absorption and durability. The main gear was installed and fitted with Dubro plastic skis. The skis are pretty small but should work fine on firmer snow.

The O.S. Engines .91 Surpass was mounted almost at the front tips of the supplied Great Planes adjustable .60-1.20 nylon engine mount. The supplied engine mounting #6 x 1" sheet metal screws were found to be soft, flat-headed wood screw types with the underside of the head bevelled 45 degrees. They should be replaced with hardened cap screws. The throttle cable outer tube was installed, leaving it loose inside the fuselage. There was enough room between the firewall and the carburetor for the cable to come straight out to the throttle arm. The Surpass header and muffler were run toward the center line just ahead of the firewall and a Hobbico silicone extension was used to exit below the cowl. The supplied red plastic spinner was too dark so a yellow Dubro unit was used with the Master Airscrew 14x6 propeller.

The large hole in the firewall was filled with lite-ply and fuelproofed, then drilled with three (3) 1/4" holes for fuel lines. The Great Planes fuel tank was installed with blocks of foam rubber. A tank support of 1/8"x1" lite-ply was glued to the former at the tank mid-point.

The cowl was very thin. On closer inspection, it appeared to be a very thin red plastic vacuum molded part with fiberglass cloth applied to the inside. The plastic was cracked during assembly and not given much hope for longevity. Thin card stock was taped to the fuselage side back far enough to allow the cowl to slip on underneath it. The card stock was then traced and cut out for the engine and the cowl was installed by placing the lip for the spinner 6 1/8" from the firewall, and the outline for the cut out traced onto it. The hole was made with a Dremel tool and carbide burr. Once it was big enough to allow the cowl to be installed with the engine in place, the cowl and fuselage were drilled for the cowl mounting screws. The fuselage holes were then enlarged to 1/8" and short pieces of inner Golden Rod were epoxied in place to be used as screw anchors. Hopefully they will not vibrate out during flight. A 1/2" sanding drum on the Dremel cleaned up the opening nicely. By starting undersized and cutting and fitting, a nice result was made. The cowl was also trimmed at the back bottom edge for a cooling hole and exit for the muffler extension. Holes were made for the needle and choke cable, and the molded openings in the front were bored out. To allow easier installation of the cowl, the opening for the prop driver was opened up to within about 1/8" of the outside edge of the raised portion. By time the airplane was completed, the cowl was curling up around its back edge and around the engine cut-out, not very good looking.

Airtronics 102 standard servos were used on all surfaces with one for each elevator half. A Cirrus CS-30BB mini-servo was installed for the throttle. The tail surface servos were mounted on hardwood rails just behind the fuel tank area. The front rail was glued to the back of the former, both glued to the fuselage sides with "L" shaped pieces of lite-ply added around them for bracing. The throttle servo was mounted on the fuselage side between the two formers.

Installing the aileron servos sticking out in the air results in an ugly installation. The aileron servo leads were attached to 24" extension cables and the connectors were taped for security. The extension cables were then drawn through the wings using the pre-installed strings. The servos were mounted according to the instructions.

At this point, confusion started. The ailerons are open framework with plywood mounting plates for the control horns built in. However, the plates are located back of the balsa leading edge of the aileron and are about 1/2" too far back to mount the horns. Great Planes technical support was contacted again and they stated that standard Great Planes aileron horns would work fine yet they would only mount into the soft balsa edge, not into the plywood plate. Other horns were considered yet still would not locate back far enough. Finally, squares of Monokote were removed at the desired horn locations and 3/4" x 3/4" squares of 1/16" birch plywood were glued to the balsa and plywood plates to provide strong support for the aileron horns. These were then covered with more Monokote and the horns were attached with small wood screws. The aileron control rods are #2-56 wire with the supplied plastic clevises at the horns and nylon keepers at the servo arms.

Two (2) Y-harnesses were used for the aileron and elevators servos. Two (2) Great Planes switch and charge jack mounts were installed in the cockpit floor just behind the servos with each switch plugging into the receiver. The receiver was wrapped in foam and placed behind the switches. A small piece of balsa was glued to the top of the former behind the pilot's head next to the top stringer and drilled for the antenna exit. Pieces of servo arm were used both as a strain relief at the exit hole and at the end of the antenna. A bar of wood was fashioned to secure the receiver. The bar screws to blocks glued to the fuselage sides. Two (2) 4.8 volt batteries were installed just behind the firewall in the foam beneath the fuel tank, one (1) 1100 mah and the other 700 mah, because that is what was on hand.

It was felt that the control horns should have more solid bases than the soft balsa. The elevators and rudder were pierced in a dozen places through the Monokote and out the other side with a pin and soaked with thin CA. Each elevator was connected using the supplied regular nylon horns and one of the 3/8" dowels with the supplied #2-56 wire. The rods cross at the tail to minimize required bending. The rods are in contact where they cross but since they are both moving together it did not seem to matter. To get both servos running the same direction it was necessary to move one toward the center of the fuselage and run the rod between the fuselage side and the servo, while running the other rod to the side of its servo away from the fuselage side. Pushrod braces were installed at the wing trailing edge former to minimize bending. With no ability to install bracing near the tail there is still too much bending in the pushrods.

The rudder was set up with a pull-pull cable system. Two (2) Goldberg standard nylon horns were used by using one of them as a "nut plate" for the other. This was done by drilling one of them with 1/16" holes to line up with the other horn, then the horns were mounted to the rudder using the supplied bolts which thread into the 1/16" holes. The cables are vinyl covered Kevlar. At each end a clevis was used with a very short control rod with an eye bent into its end to accept the cable, which loops through the eye and back through a metal sleeve. The metal sleeve is then crimped onto the cable. Adjustment is possible at the clevises. The supplied nylon clevis was used at the rudder and metal Sullivan units at the servo, with their metal retainer clips and locknuts. The locknuts were glued with CA for security.

With the exit holes for the rudder near the bottom of the fuselage and the ones for the elevator just below the elevator, there was no interference between the rods and cables. Goldberg molded fairings were installed in the slots at the tail, hopefully to minimize oil penetration. The supplied throttle cable was a nice braided steel unit that was very flexible. It operated perfectly with a short, nearly straight run.

The recommended control surface throws were set for both high and low rates and throttle adjustment were made. After reading reviews of the kit and online comments from other builders, the elevators were trimmed slightly down, about 1/16".

Great Planes self-adhesive foam tape was applied to the wing saddle after it was fuel-proofed with thin CA. Two (2) lengths of black rubbery plastic tubing were supplied, one slit down its length, the other not. The slit one was installed as cockpit coaming with RC-56 glue after CA was applied to the cockpit rim to make it hard.

An instrument panel was made of 1/8" balsa. The panel decoration was drawn on a CAD program, printed, glued to the wood, and sprayed with clear Krylon acrylic plastic. (The instrument panel CAD file is available for download in DXF format.) Balsa spacers were added to the back of the panel, which was then glued to the former at the front of the cockpit. The windscreen was judged too tall and trimmed down a bit and installed with RC-56 glue. Black trim covering was applied to the base of the windscreen. A Williams Bros. 1/4 scale pilot was assembled and built up with 1/2" balsa under his base. He was painted with a red-and-yellow helmet to match the plane. Sunglasses were fashioned from black polystyrene and installed. The molded fuel level fairing was placed on the fuselage, its perimeter marked, the Monokote removed, and the fairing glued on.

The next problem encountered was how to balance this monster. A method was required that could balance the plane precisely without denting the balsa wing. A triangular piece of minicell foam was found that looked perfect for this application. The foam is soft but firm enough to support the Spacewalker. It was cut in two pieces that were about 3" cubes. Short pieces of wire were inserted under the pointed tops and the pieces mounted to the tops of two sawhorses. This way the plane could be balanced with the landing gear hanging between the sawhorses. The wires protrude from the foam enough to secure a measuring tape. Great Planes specifies a balance point 4 1/4" behind the wing leading edge. This calculates at 31.5% of the 13.5" chord and was judged too far back for test flights. To bring the balance point up to about 29 percent of chord at 3 7/8" back, 1 1/2 oz. of lead were attached to the engine mount. A small balsa block was hollowed to accept 1/2 oz. of lead shot and epoxy and glued to the left balsa wingtip. The molded plastic wingtips were then glued in place.

With the plane secured to a ground stake, the engine was started and adjusted. At this point it was mid-afternoon and very warm and sunny. The snow had become loose and slushy, barely supporting the aircraft. A taxi test was made while up-elevator was held. When the elevator was relaxed to neutral the plane nosed into the snow. A second taxi run was made and at about 1/2 to 2/3 of take-off speed, with up elevator still held, the plane took off at a nose-high angle of about 30 degrees. The nose was quickly lowered and the plane smoothly climbed to safe altitude. At this very low airspeed, down trim was needed to level the flight path of the plane. Slight aileron trim was made. A couple of short circuits were flown. Ailerons were switched to low rate. More airspeed was thought desirable and at about 1/2 throttle a very moderate airspeed required more down trim. The plane seemed very light and floaty and easily handled, definitely flying "on the wing". It gave the impression of flying a low-wing Cub. This is at 6300 feet elevation. At this point the engine started running roughly, the speed pulsing more and more. Throttle was advanced without affect and the engine died. A smooth and slow approach was made to a soft landing. The Spacewalker skied 20 yards and nosed over, flipping into the soft snow. Upon retrieval the muffler with header pipe was hanging from the pressure line and had apparently caught in the skis, flipping the plane. The exhaust flange on the engine was broken. It apparently broke in flight, depressurizing the fuel tank, causing the engine to die. The nylon wing bolt mounts were also found to be broken. One of the soft engine mounting screws was also broken.

Repairs were now necessary before additional flight tests could be made. What appeared true is that even more down trim is required. The plane seemed very well powered and very easy to fly. It would probably have been very difficult to handle at the recommended balance point.

Great Planes offers a convincing sport scale ARF model of the Spacewalker, in quarter scale, for a very reasonable price. The construction and covering appear well done. The Monokote can be tightened down nicely and can easily be matched later for repairs. Assembly is mostly well thought out and could be accomplished by any moderately skilled modeler. The molded parts are not going to withstand any punishment, so better quality replacements should be included in the budget. The recommended engine sizes are appropriate. The heavier #4-40 size control hardware required by the IMAA should probably be used with larger engines and by pilots wanting faster and more aerobatic performance. It is expected that further flight testing will show the Spacewalker to be a fun-to-fly sport plane with moderate aerobatic capacities, and gentle enough handling to be flown comfortably by most intermediate level flyers.