Sig Mfg. Co., Inc....401-7 South Front Street....Montezuma, Iowa 50171

The Spacewalker Story

In the small town of Henderson, North Carolina, lives a man who has been quietly designing and selling his homebuilt designs for several years now. His J-3 Kitten won Best New Design at the 1983 Sun-'N-Fun EAA Fly-In. He won a Grand Champion Prize at Oshkosh in 1984 with his J-4 Sportster, and in 1985 at Oshkosh, his J-6 Karatoo won the Outstanding New Design award. This prolific designer then decided to build himself a personal fun plane and in 1986 it flew for the first time. That airplane was named the Spacewalker and the designer of all of these prize-winners was Jesse Anglin.


The general layout of the spacewalker (low-wing, open-cockpit taildragger) was inspired by a ride that Jessie had in a PT-19 years ago. Power is provided by a 65 h.p. Continential with it's cyliners hanging in the breeze like a cub. Even though it was meant to be a personal airplane, public reaction has convinced him to market the plans and sell component parts through his company, Country Air, Inc.

The classic lines of the Spacewalker remind most aviation enthusiasts of Pete Bower's Fly Baby or the Ryan trainers. One writer even thought at first glance it was a Les Long creation of the Great Depression era. This is exactly the kind of feeling that Jesse wanted to evoke with this design. With ultra-efficient, gas-sipping, cross-country machines dominating the homebuilt industry today, it is strangely refreshing to see a brand new airplane designed solely for the pure pleasure of flight.

The Spacewalker fuselage is a welded steel tubing structure with wood formers and stringers in the turtledeck to give it some shape. The wing is fully cantilevered with a massive center section main spar and box spars in the outer wing panels. Drag loads are handled by diagonal compression trusses between the spars. The wing ribs are routed out of 1/4" plywood and the wingtips are molded fiberglass. The tail surfaces are simple welded steel tubing. Jesse sells plans for the Spacewalker as well as many component parts, including the completely welded fuselage frame.

When Maxey Hester (then Vice-President, Sig Mfg. Co.) saw a picture of the Spacewalker in the EAA magazine (Sport Aviation), he decided that a model of this airplane would be the perfect showplane for his new four-cylinder O.S. Pegasus engine. In December '86, he and Hazel Sig visited with Jesse Anglin and returned to Montezuma with a full set of plans for the full-scale Spacewalker and announced that they were going to build one! After waiting many months to receive all of the component parts from Jesse, work on the full-scale bird commenced here at the Sig factory. With much help from Dorothy and Burnis Fields of Interlachen, Florida, Maxey had his airplane finished and ready to fly in twelve weeks! It was the first Spacewalker, other than Jesse's, to be finished and flown.

Jesse Anglin has made many changes to his Spacewalker since it first flew. Originally, only the rear set of tail brace wires were installed and the exhaust pipes on the engine flared outward at the ends. Jesse said that the open pipes gave the airplane a distinctive sound, but it was just too loud to live with. The pipes were later routed into the cowl where they met at a centre muffler. Two more pipes route the exhaust straight down out of the bottom of the cowling. Jesse also added another set of tail brace wires to the front of the stabilizer at about the same time the changes were made to the exhaust system. Several months later he changed the shape of the windshield to improve the looks and wind protection. Also the engine originally had no cylinder cooling shrouds, but after a long cross-country trip in hot weather, he decided that they were needed. His latest change was to clip the outer wing panels two rib bays on each side.

On the other hand, Maxey had not made any visible changes to his airplane - he was happy with it just the way it was. More Spacewalkers were then being constructed all around the country. Most of these would probably have some minor differences in appearance because most homebuilder's love to modify designs to suit their taste. Maxey stuck very closely to the plans, so his airplane was almost identical to Jesse's except for the color of the paint!

About The Sig Model

The Sig 1/3 scale Spacewalker was designed with an eye towards scale construction techniques. The plywood ribs with lightening holes, the box spar with laminated spruce caps, the detachable wing panels, and the open fuselage framework are all copied from the full-scale bird. Most of the models built from this kit will end up weighing about 20 pounds, giving a wing loading of 25.6 oz.sq.ft.

We are all very excited about the flight performance of the model. We've never seen an airplane with that long of a wing and that much dihedral do rolls so axially. And according to Jesse Anglin, the full-scale Sapcewalker has the same trait. Loops, snaps, spins, and inverted flight are all so easy to do. With 1800 of wing area, landings are slow and stable. As for its scale accuracy, it was designed using the full-scale drawings. This is one airplane that will definately put a smile on the faces of scale and sport pilots alike!

Scale Data Sources

Builders that plan to enter their Spacewalkers in competition will need to collect some scale data on the particular aircraft they have chosen to model. The following list of sources should prove helpful.


  • SIG MFG. CO.-Color photo packs of both Jesse's (black and red) and Maxey's (red and yellow) airplanes.

  • KITPLANES, September 1988 -This issue features a beautiful color cover shot of Hazel and Maxey in their Spacewalker flying over the Iowa landscape. The accompanying article on pages 26-31 is the definitive piece of literature on the two aircraft to date. Full color photos include flight shots, ground shots (with models), and one of Hazel's instrument panel. Article by LeRoy Cook.

  • KITPLANES, August 1988 -A color photo on page 11 features Maxey's Spacewalker at Sun-'N-Fun '88 when his N number was still on the side of the fuselage. Jesse's and Hazel's airplanes are in the background, each with a model displayed.

  • SCALE R/C MODELER, August 1988 -On page 52 is a color photo similar to the previous month's cover shot. Although smaller, this photo shows more detail. A Sig model is in the foreground.

  • SCALE R/C MODELER, July 1988 -Cover photo. Although this color cover shot isn't particularly useful for documentation, it is a nice close-up photo of Hazel sitting in her Spacewalker at the 1988 Atlanta IMS Show.

  • SPORT AVIATION, October 1986 -On page 21 is a good color flight shot of the Spacewalker with Jesse at the controls. This is the photo that originally attracted Maxey to the design and led to his first trip to Jesse's hanger a few weeks later.

  • LIGHT PLANE WORLD, October 1986 -Complete article and photo study. Photos show the airplane with the original windshield and exhaust system.

  • HOMEBUILT AIRCRAFT, March 1987 -Complete article and photo study, including precover construction photos. The original windshield and exhaust system are shown.

  • SPORT AVIATION, July 1987 -On page 40 is a striking color photo taken at Sun-'N-Fun '87 of Jesse's airplane with our first prototype model next to it. The article is entitled "Dynamic Modeling," but there's no mention of the Spacewalker.

  • PRIVATE PILOT, June 1987 -On page 69, is another small photo of Jesse's bird and the scale model at Sun-'N-Fun. Interestingly, the caption reads "Skywalker," a common mistake when talking about this airplane.

  • KITPLANES, July 1987 -The Spacewalker is featured on the cover of this issue. It is a flight shot with Jesse at the controls wearing his "color coordinated" helmet. The helmet is a feature you may want to add to your scale pilot. Shows the original windshield, new exhaust system, and no cylinder shrouds. Inside is another color shot and a short article.

  • SPORT PILOT, July 1987 -There's an inset photo on the cover with Jesse flying over a beach. The article features a two page color photo of N107JA in flight and many black and white photos, including one of the instrument panel. Again, this has the old windshield, new exhaust, and no cylinder shrouds. The article is very good and includes a pilot report.

Die-Cut Balsa
11/8"x3"x20-1/2" Sheet No.1 FS-1, FS-2, Apron pieces
Silkscreened Balsa
21/4"x3"x14" Sheet No.2 WS-1, WS-2, WS-3 13/8"x4"x27" Sheet No.3 Stab, Elevator, Rudder Parts
Sheet Balsa
23/32"xI"x36"' Bottom Wing Sheeting, Center Sheeting 43/32"x1-1/2"x30'' Center Section T.E., & Aileron Well Sheeting 43/32"x1-1/2"x36'' Outer Panel T.E. Sheeting 23/32"x2"x36" Aileron Top, Center Section, & Servo BaySheeting
43/32"x3"x30" Center Section Sheeting 43/32"x3"x36" Wing PanelloE. Sheeting 31/8"x4"x21" Front Deck Sheeting 23/16"x1-1/2"x30" Aileron Leading Edge
13/16"x4"x12" Landing Gear Fill-In 21/4"x3"x12" Main Frame Fill-In 23/8"x4"x4-1/2" Fuselage Bottom
Block Balsa
21/2"x3-1/4"x2" L.G. Support Block 25/8"x3-1/4"xI" L.G. Support Block


Stick Balsa
183/32"x1/4"x36" Capstrips 23/32"x3/4"x30" Bottom Aileron Sheeting 11/8"x1/8"x24" Top Main Spar Spacers 81/8"x1/4"x36" Aileron Spars, Fill-Strips, Fabric Attach Strips
71/8"x3/8"x36" Top Stringers, Cable Exit Guides, Fill-Strips 31/8"x3/4"x36" Leading Edges 23/16"x1/4"x18" Fill-Strips 33/16"x3/8"x36" Tail Surface Diagonal Ribs
181/4"x1/4"x36" Forward Spars, Main Frames, Cross-Braces, Stringers 61/4"x1/2"x36" Rear Spars 31/4"x7/8"x36" Leading Edge Caps 33/8"x3/8"x36" Tail Surface Ribs
53/8"x3/4"x36" Tail Surface Frames 13/8" Triangle x2-1/2" Fin L.E. Brace 13/4" Triangle x36" PW Brace, Hold-down Block Brace, L.G. Block Brace 1I" Triangle x8" Firewall Brace
11/2"x 1-1/2"x8" Special Shaped T.E. Fill-In Block
13/8"xI"x1-1/2" BASSWOOD Control Horn Mount 21/2"x19/32"x4" BASSWOOD Rear L.G. Blocks, Grooved 21/2"xI"x4" BASSWOOD Front L.G. Blocks, Grooved 23/4"x3/4"x3" BASSWOOD Wing Mounting Blocks
23/16" dia.x2-1/2" BIRCH DOWELS Pushrod Ends 25/16" dia.x1-1/2" BIRCH DOWELS Wing Hold-Down Dowels
51/8"x3/8"x36" Stringers, Stab and Fin Brace 41/8"x3/4"x6" Main Spar Laminate 41/8"x3/4"x17-7/8" Main Spar Laminate 41/8"x3/4"x30-1/8" Main Spar Laminate
41/8"x3/4"x48" Main Spar Laminate 23/16"x1/2"x4-1/2" Spruce Spar Doubler 61/4"x1/4"x36" Fuselage Main Frame 11/4"x1/2"x 6" Tiller Bar Mount
13/8"x3/8"x36" Servo Rails, Elevator Joiner
Die-Cut Popular Plywood (Lite-Ply)
11/8"x8"x22" F-2, F-3, F-4, F-5, F-6, F-l, F-B, F-9, F-10 11/8"x8"x22" F·1A, PT-1, PB-1, Hatch Supports, Wing Center Sheeting 11/8"x8"x22" PT-2 21/8"x8"x22" PS-1
21/8"x9"x22" WTR, W-1A,.W-4A, SW-1, SW-2, SW-3 21/8"x6"x18" W·2, W-4 Wing Ribs 21/8"x9"x18" W-2, W-3, W-4 Wing Ribs 41/8"x12"x18" W-1, W-2, W-3, W·4 Wing Ribs
11/8"x7"x36" PS-2, PB-2, G-1, TM, TWM, F·6A, PF 11/8"x9-1/2"x36" SW-4 Shear Webs
Die-Cut Birch Plywood
11/16"x10-1/2"x7" Instrument Panel, JW·1, Dihedral Gauge, Wheel Pant Plates 13/32"x4·1/2"x9" DB·3, DB-4, Hold-Down Plates, L.G. Mount Plates 25/32"x7·1/2"x8" F·1 15/32"x2-1/2"x17" DB·1, DB·2
15/32"x10"x12" JW-2, JW-3, IW-1, IW-2
Sawn Plywood
121/8"x3/8"x10-1/2" LITE-PLY Rib Stiffeners 21/64"x5/8"x48" BIRCH PLYWOOD Wing Straps 23/32"x3"x4·1/4" BIRCH PLYWOOD Servo Access Hatches 21/8"x1"x6" BIRCH PLYWOOD PW
23/16"x1"x4" BIRCH PLYWOOD L.G. Block Doublers 21/4"x4·11/32"x1-5/16" BIRCH PLYWOOD JW-4
Wire Parts
13/32" dia. Straight Wire for Servo End of Elevator Pushrod 11/8" dia. Formed Top Shock Strut Wire 11/8" dia. Formed Bottom Shock Strut Wire 13/16" dia. Formed Front Main L.G. Wire
13/16" dia. Formed Rear Main L.G. Wire
Plastic Parts
1Left Dummy Engine Cylinders 1Right Dummy Engine Cylinders 1Cylinder Shrouds 1Fuel Cap Cover, Shock Spring Halves, Compass Halves
1.030"x8-1/2"x17" Clear Butyrate for Windshield
Fiberglass Parts
1Cowling 2Wheel Pants - LEFT AND RIGHT ARE THE SAME 1Left Wingtip 1Right Wingtip
Miscellaneous Parts
11/2" dia. x3 ft Green Foam Cockpit Coaming, Grooved 13/32" wide x7 ft Cockpit Lacing 132" long Fiberglass Pushrod Shaft (for elevator) 112"x19" 6 oz. Fiberglass Cloth (for L.G. & Wing Joint)
1Small Nylon Tubing (for Rudder Cable Guides & Throttle Pushrod) 120" long Steel Cable (for throttle pushrod) 1Full·Size Plans· Plate 1 1Full·Size Plans - Plate 2
1Full-Size Plans - Plate 3 1Full-Size Plans - Plate 4 1Decal Sheet 1Instruction Book
Special Extruded Aluminum Parts
22" long Rear Wing Joiner Channels 23" long Front Wing Joiner Channels 26" long Rear Wing Joiner Spars 29" long Front Wing Joiner Spars


Hardware Pack
62·56 x1/2" Mounting Bolts (1 rudder control horn, 5 tail brace wires) 24-40 x3/8" Mounting Bolts (for elevator control horn) 84-40 x1/2" Mounting Bolts (for rear wing joiner channels) 84-40 x1" Mounting Bolts (for front wing joiner channels)
106·32 x3/4" Mounting Bolts (for wing joiner spars) 16·32 x1" Mounting Bolt (for tiller bar) 64-40 x3/8" Socket Head Bolts (set screws for wing joiner channels) 26-32 x3/8" Socket Head Bolts (set screws for wheel pant mounts)
410-32 x1" Socket Head Bolts (for engine mounts) 62·56 Hex Nuts (1 rudder control horn, 5 tail brace wires) 16-32 Hex Nut (for tiller bar) 84·40 Aircraft Lock Nuts (for front wing joiner channels)
106·32 Aircraft Lock Nuts (for wing joiner spars) 104-40 Blind Nuts (8 for rear wing joiner channels, 2 for elevator horn) 410-32 Blind Nuts (for engine mounts) 8#4 Flat Metal Washers (for front wing joiner channels)
12#6 Flat Metal Washers (2 for tiller bar, 10 for wing joiner spars) 2#8 Flat Metal Washers (for wheel spacers) 8#2 x3/8" Sheet Metal Screws (for servo access hatches) 10#2 x1/2" Sheet Metal Screws (6 for cowl, 4 for tail brace wires)
4#4 x3/8" Sheet Metal Screws (for wheel pant mounts) 8#4 x1/2" Sheet Metal Screws (for I.g. straps) 21/4·20 x1·1/2" Molded Nylon Bolts (for wing attachment) 1Molded Nylon Tiller Bar
23/16" I.D. Molded Nylon Wheel Pant Mounts; with Brass Inserts 1Extra Large Molded Nylon Control Horn (for elevator) 1Molded Nylon Rudder Control Horn 290deg. Molded Nylon Bellcranks (for aileron control horns)
4Large Molded Nylon Landing Gear Straps 44·40 x8" Threaded Rods (2 aileron, 1 elevator, 1 rudder) 44-40 Metal RIC Links (2 aileron, 1 elevator, 1 rudder) 34-40 Solder Links (2 aileron, 1 elevator)
32-56 Nylon R/C Links (2 rudder, 1 throttle) 12-56 Solder Link (for throttle pushrod) 12-56 Threaded Coupler (for throttle pushrod) 23/16" Wheel Collars (for main landing gear)
26·32 Headless Set Screws (for 3/16" wheel collars) 14Steel Brace Wire Attach Tabs 103/32" O.D. x1/2" long Aluminum Tubing, (for tail brace wires) 1.027 x200" roll Steel C/L Cable (for rudder control and tail brace wires)
1roll - Soft Copper Wire (approx. 21 ft.) 15Giant Size XX Molded Nylon Hinges 15Steel Pins (for Hinges) 1Tailwheel Assembly (bagged separately)
NOTE: All of the hardware for the aluminum wing joiners is packed with the aluminum parts in a separate bag.


There are many different glues available today for model construction that it can be confusing to even the experienced modeler. To simplify matters, most glues can be classified as one of four types:
  1. Fast cyanoacrylate adhesives (abbreviated as C/A) such as Sig CA, Hot Stuff, Jet etc.
  2. Easy to use water-based wood glues such as Sig-Bond (yellow) and Sig Super-Weld (white).
  3. Super strong (but heavier) two-part epoxy glues such as Sig Kwik-Set (5 minute cure) and Sig Epoxy (3 hour cure).
  4. Traditional solvent-base model cements such as Sig-Ment.
Each of these types has different characteristics and advantages. Often times, the choice of which type to use is strictly a matter of personal preference based on your experience with a previous model. To help speed up assembly, C/A glue is recommended for general construction. You should also have on hand some epoxy (both 5 min. and slow dry) and Sig-Bond because these glues are called out in several places in these instructions.

Sig CA, like mose brands of cyanoacrylates, come in three viscosities- thin, medium, and thick. An accellerator spray and debonder are also available and are described below.
  • Sig CA Thin - Watery consistency, thin CA should only be used when the two parts to be joined are in perfect contact with zero gap. Capilliary action pulls this glue deep into the wood resulting in a very strong bond and it dries in just a few seconds. Thin CA can be used to tack assemblies together, but these joints should be glued again later with medium or thick CA.
  • Sig CA Medium - Our medium thickness CA is excellent for almost any step during construction. The extra thickness allows the glue to fill small gaps, but it does dry a little slower than a thin CA. If you want only one type of C/A, use medium thickness.
  • Sig CA Slow - This thickest formula is good for filling large gaps and building up strong fillets at joints requiring extra strength. It also dries slow enough to allow you to apply it to one part and position it on another before it dries. (With the thin and medium C/A's, the parts must be in contact and positioned correctly before glue application.) This feature is useful when laminating large sheeted areas like a fuselage side and a fuselage doubler.
  • Sig Kwik-Shot Accellerator - Spraying accellerator on CA (any thickness) will cure it almost instantly. Although CA is fast, it's sometimes nice to speed it up even more.
  • Debonder - This can be used to separate parts, but you'll probably use it for unsticking your fingers more than anything else!


CAUTION: Some people have experienced allergic reactions when exposed to epoxy or cyanoacrylate glues. This is very rare. However, it is extremely important that such glues, and also paints, thinners and solvents, be used with adequate ventilation to carry fumes away.

Notes Before Beginning Construction

Any references to right or left refers to your right or left as if you were seated in the cockpit.

To build good flying models , you need a good straight building board. Crocked models don't fly well! The building board can be a table, a workbench, a reject "door core" from the lumber yard, or whatever- as long as it is perfectly flat and untwisted. A 2ft.x6ft. board is recommended for the Spacewalker.

Cover the top surface of the building board with a piece of celotex-type wall board or foam board, into which pins can be easily pushed. Don't hesitate to use plenty of pins during assembly to hold drying parts in their correct position.

When pinning or gluing parts directly over the full-size plans, cover the plan with wax paper or plastic kitchen wrap to prevent gluing the parts to the plans.

The balsa die-cut parts have identification numbers printed on them. The plywood die-cut parts do not. Use the "Key to Die-Cut Birch Plywood Parts" and the "Key to Die-Cut Lite-Ply Parts", to mark the identification numbers on the corresponding plywood and Lite-Ply parts.

Leave all the die-cut parts in the sheets until needed for construction. Remove pieces from the sheets carefully. If difficulty is encounted, do not force the part from the sheet. Use a modeling knife to cut it free.


All of the other kit parts can be identified by the "Complete Kit Parts List". Sort the different sizes of sticks and sheets into individual piles to avoid confusion during building. Cut all long pieces of balsa first, followed by medium lengths, before cutting up any full length strips into short pieces.


An assortment of different size sanding blocks are indispensable tools for model construction. A good general purpose block can be made by wrapping a 9"x11" sheet of sandpaper around a piece of hardwood or plywood. Use three screws along one edge to hold the overlapped ends of the sandpaper. Put 80-grit paper on the block during general construction. Switch to 220-grit paper for final finish sanding just before covering.

Another handy block can be made by gluing sandpaper onto a 24" or 36" long piece of aluminum channel stock. Most hardware stores carry a rack of aluminum in various sizes and shapes. This long block is very useful for sanding leading and trailing edges accurately.

About The Building Sequence

The quickest and most efficient way to complete a model is to work on several pieces at the same time. While the glue is drying on one section, you can start on or proceed with another part. Work can even go forward on several sections of the same assembly at the same time, such as the front and rear sections of the fuselage. Keep in mind that the numbering sequence used in these instructions was chosen as the best way to explain the building of each major component and is not intended to be followed exact one-two-three fashion. Start on the wing at No.1 and after doing as many steps as is convenient, flip over to "Fuselage Construction" and do a step or two or three, then over to "Tail Surface Construction" and so forth. You will, of course, arrive at points where you can go no farther until another component is available. For example, you need a nearly completed wing before the fuselage can be entirely completed. Plan ahead! Read the instructions completely and study the full size plans before beginning construction.

Radio Requirements

You will need at least a four-channel radio system for your Spacewalker to operate the ailerons, elevator, rudder and throttle. Heavy-duty servos intended for use on 1/4-scale models are required for all of the flight controls. Also, use a receiver battery with at least a 1000mA capacity to power those servos for a safe amount of time. Be certain that your radio system's frequency is approved for use in R/C model aircraft. Using a frequency assigned to R/C model cars not only endangers your model to interference from model car drivers (who may not be in sight), it also is against the law.

About Printed Wood Parts

To answer the question we are sometimes asked - no, we do not print parts on wood to save money. It is actually more expensive to print the parts using a silk screen press than it is to run an equivalent sheet through our automatic feed die cutting machine. If we hand-sawed the parts it would be even more expensive and the labor cost would have to be added to the kit price. We believe that most modelers would rather cut their own out and save the cost. Since there are not many thick parts in our average kit, it really doesn't consume a lot of the total building time for the builder to do the parts.


The Spacewalker has a wing designed with removable outer panels so that it can be "broken down" into three easily-managed pieces for transporting. The outer panels are joined to the center section using extruded aluminum wing joiners and are held in place by three set screws on each side. The following instructions are strictly for the three-piece wing as shown on the plans.

Some modelers may prefer to build the wing as a one-piece unit. This will save about a pound in weight (through the omission of all the wingjoining hardware), but will require a full-size van or model trailer to transport the model. If you wish to build a one-piece wing instead of the standard three-piece wing, please read and follow the instructions concerning "How to Build a One-Piece Wing", included at the end of the Wing Construction Section. You should also read "About the Ailerons", included further on, before beginning work on the wing.

Notice that a nearly completed wing assembly is needed to complete construction on the fuselage. It is recommended that you begin to build the wing first so that it will be ready when you reach that point in the fuselage instructions.


Wing Subassemblies

Before beginning construction on the wing, there are a number of subassemblies that should be built and set aside until needed. This is done to avoid interruptions during the flow of the wing construction.


The main wing spars are laminated from 1/8"x3/4" spruce sticks as shown in the "Main Spar Assembly Diagram" on the plans (Plate 3). Build four main spars using a thin film of slow-drying epoxy to join each laminate. It is very important that the main spar assemblies be kept perfectly straight while drying. Any 'bends or twists built in now are there to stay!


Join two die-cut 1/8" lite-ply W-IA sub-ribs to two W-l wing ribs, being certain to make one left and one right. These subassemblies will serve as the two center ribs in the wing center section. The remaining two W-IA sub-ribs are not installed until the wing has been fitted to the fuselage.


Use scrap pieces of 1/16" balsa to join together two W-2 wing ribs. Make two of these subassemblies. These are the two ribs that will meet at the wing joint when the outer panel slides in place. The 1/16" balsa scraps serve as temporary spacers that hold the ribs in perfect alignment. After construction, the spacers are cut away, so locate them around the edges where it will be easy to get at them.


  1. Again, use scrap pieces of 1/16" balsa to join two W-4A sub-ribs to two W-3 wing ribs, being certain to make one left-hand and one righthand. These subassemblies are used at the inboard ends of the ailerons.
  2. Use scrap pieces of 1/16" balsa to join W-4A sub-ribs to two W-4 wing ribs. Make one left-hand and one right-hand. These subassemblies are used at the outboard ends of each aileron.


Prepare the aluminum wing joiner channels and wing joiner spars as shown in the diagrams below.

Carefully cut out the templates and accurately position them on the backs of the aluminum joiner channels. Use a punch to mark the channels at the center of each hole. Remove the templates, and drill carefully and slowly at the punch marks. Drill all holes with #33 drill bit and use a drill press if at all possible.



Epoxy together two die-cut 5/32" plywood IW-1 inner webs and use a weight to hold them flat while drying.


Glue the 3/16"x1"x4" plywood landing gear block doublers to the tops of the front landing gear blocks.

Wing Construction

The wing is built in two halves, each consisting of an outer panel and half of the center section. After construction, the outer panels are cut free and the center section halves are joined to complete the three-piece wing.


  1. Pin down one of the laminated spruce main spars over the plans.
  2. Glue and pin all of the 1/8" lite-ply wing ribs into position except for the W-1/W-1A subassembly at the wing center. Be sure to use the wing rib subassemblies that you prepared earlier in steps 3 and 4.
NOTE: The large lite-ply ribs may have a tendency to warp, making it difficult to align them on the plans at this time. To counteract this, be sure to pin each rib accurately at the rib alignment tabs. Then, as each spar or leading edge piece is added, gently pull each rib into position while gluing. By the time you have added the front spars, the rear spars, and the leading edges, the ribs should all be perfectly straight.


Glue another laminated spruce main spar assembly to the tops of the ribs. Use a builder's triangle to make certain each rib is vertical.


Locate the die-cut 1/16" plywood dihedral gauge. Position the W-1/W-1A wing rib subassembly in its position on the plans using the dihedral gauge to insure that it is at the proper dihedral angle. Glue the rib assembly to the spars.


Glue scrap pieces of 1/4" sq. balsa to the sides of the rib alignment tabs to accept pins. It's a lot easier to pin through balsa than lite-ply!


  1. Cut a 1/4" sq. x12" balsa forward spar from one of the 36" lengths provided. Glue this spar to the top of the center section ribs. The outboard end of this spar should be positioned about halfway between the two W-2 ribs at the wing joint.
  2. Glue a 1/4" sq. x 36" balsa forward spar into position on top of the outer panel wing ribs with its inboard end butted against, but not glued, to the center section forward spar.


  1. Cut a 1/8"x3/4"x12" balsa leading edge for the center section and glue it in place at the front of the ribs, again placing the outboard end between the two W-2 ribs at the wing joint.
  2. Add the 1/8"x3/4"x36" balsa leading edge to the outer panel.


  1. Cut a 1/4"x1/2"x12" balsa rear spar from one of the 36" lengths provided and glue it to the top of the center section ribs.
  2. Glue a 1/4"x1/2"x36" balsa rear spar in position on top of the outer panel wing ribs. This spar should butt up against the center section rear spar at the wing joint, but should not be glued to it.
  3. Repeat parts a. and b. of this step for the bottom rear spar. You will have to slide the spars under the ribs, then lift them into position.


  1. Cut a twelve-inch length of 3/32"x1-1/2" balsa from one of the 30" lengths provided (not one of the 36" pieces!) to serve as the center section trailing edge sheeting. Glue it in place on top of the center section wing ribs. Careful! Make sure that the back edge of the sheet is in the right place, directly above the trailing edge on the drawing.
  2. Glue the 3/32"x1-1/2"x36" balsa trailing edge in place on the outer panel, again being careful to check for the correct overhang.

Wing Joiner Assemblies


  1. Trial fit an IW-l inner web subassembly (from Step 6.) in its position between the spars and trim as necessary, but do not glue it in place. Also, trial fit a die-cut 1/16" plywood JW-l joiner web and, again, trim as necessary.
  2. Epoxy the IW-l subassembly to the JW-l joiner web as shown in the diagram. Wipe away any excess epoxy before it dries.
  3. Trial fit the die-cut 5/32" plywood IW-2 and JW-2 webs as you did before. Epoxy the pieces together as shown in the diagram. Notice that only the JW-2 joiner web closest to the wing joint has an IW-2 inner web glued to it. The outboard JW-2 web should also be fitted in position, but not glued.


  1. Insert one end of a front wing joiner spar into a front wing joiner channel so that it is flush with one end of the channel. Tighten the socket-head set screws snugly against the joiner spar.
    IMPORTANT: To avoid any misalignment later on, it is important that the set screws be tight while installing the aluminum wing joiner assembly.
  2. When dry, place the joiner webs in their position in the wing to check that they still fit, but don't glue.
  3. Position the wing joiner assembly on the joiner webs and clamp it in place. The assembly should be centered between and parallel to the spars. When satisfied that it is positioned correctly, mark JW-l and JW-2 at the drill holes. Remove the clamps, wing joiner assembly, and joiner webs from the wing.
BUILDER'S TIP: Scrap pieces of plywood placed against the back side of the spars provide a convenient
surface for the clamps used in this step.


  1. Accurately drill JW-l at the marks with a 3/32" drill bit and the JW-2 pieces at the marks with a 1/8" drill bit. Reinstall the joiner webs in the wing again, but do not glue.
  2. Bolt the aluminum wing joiner assembly in place using the hardware as indicated on the plan (Plate 3, see "Section A-A" and "B-B").
  3. When you are satisfied that the joiner webs and the aluminum wing joiners are fastened correctly, pull the whole works away from the spar. Spread epoxy over the back of the joiner webs where they contact the spar, then clamp them in place (being careful not to glue together the aluminum pieces). When dry, give the joiner webs and inner webs a generous coating of epoxy from the backside to insure a solid glue joint.


  1. Assemble a rear wing joiner channel and rear wing joiner spar and tighten the set screw.
  2. Lightly sand the front face of the rear spars where the joiner webs sit, just enough to provide a flat gluing surface.
  3. Pin or tape JW-3 and JW-4 in place, then clamp the rear wing joiner assembly on top of them. Carefully line-up the aluminum joiner so that it is parallel with the front joiner, and mark the positions of the drill holes. Remove the joiners and the webs from the wing.
  4. Carefully drill JW-3 with a 5/32" drill bit and JW-4 with a 1/8" drill bit. Bolt the wing joiner assembly on the joiner webs and make certain that it all still fits in the wing. Notice that the rear spar will have to be relieved slightly in spots to accept the blind nuts on the back of JW-3. When satisfied with the fit, epoxy the joiner webs to the front face of the rear spars.


  1. Trim the die-cut SW-1 shear web to fit between the two W-1 wing ribs. Notice that the bottom edge of this shear web is even with the top of the cutout for the landing gear block in W-1A.
  2. Glue a die-cut SW-2 shear web in place on the front of the spars. (No shear webs should be installed on the backside of the spars now because you will need to get at the pins in the bottom spar when it is time to remove the wing from the building board.)
  3. Lightly sand flat spots on the front of the rear spars (as you did before) where the SW-3 shear web and DB-4 dihedral brace are located, then glue SW-3 in place. DB-4 will be glued in later.
  4. Glue the die-cut SW-4 shear webs to the front of the main spars in the outer panel.


  1. Sand the top of the leading edge to the contour of the ribs. Be careful to avoid sanding the ribs and changing their shape.
  2. The leading edge is sheeted with 3/32"x3"x12" balsa on the center section (cut from 30" material) and 3/32" x 3" x 36" balsa on the outer panels. The sheeting should overlap onto the forward spars only about halfway. Start gluing at the spars and work forward to the leading edge, pinning or taping the sheets in place as you go. There will be excess sheeting forward of the leading edge.


Fill the gap at each W-2, W-3 and W-4 rib above the main spar with spacers made of short lengths of 1/8" sq. balsa. When dry, sand the spacers down even with the tops of the ribs.


Trim the 3/16"x1/2"x4-1/2" spruce spar doubler to fit between the ribs as shown on the plan. Glue this piece to the bottom spar only. This doubler is there to reinforce the weak point in the spar when a relief is cut in it later to pass the aileron pushrod.


Cut two 1/8"x1/4" balsa aileron spars to the correct length and glue them to the wing, one on top and one on bottom.


Use a 3/32"x2"x36" balsa sheet for the top aileron sheeting (save the excess for later). Glue this sheet to the top of the wing as shown. This sheet will eventually be sliced down its length when the aileron is cut from the wing.


25. Glue the 3/32"x1/4" capstrips to the tops of the wing ribs and aileron ribs as indicated on the plan. When dry, remove the wing from the building board.


Glue in the remaining SW-4 shear webs on the back of the main spar.

Now is a good time to look over your basic wing structure for any joints that may need another coat of glue. In particular, inspect the bond at all the rib, spar, and web joints.


  1. Carefully cut away all of the rib alignment tabs, then sand the bottom of the ribs and the rear edge of the trailing edge sheeting to the airfoil shape.
  2. Glue the 3/32"x1-1/2" balsa trailing edge sheeting to the bottom of the wing. Use epoxy glue where the bottom sheeting joins the top sheeting. The epoxy will not warp the trailing edge (as water-based glues might) and will strengthen the sharp edge so that it is not so easily damaged.


  1. Notch the bottom trailing edge sheeting in the position shown on the plans for the die-cut 3/32" plywood wing hold-down plate.
  2. Cut the 1/2"x1-1/2" special-cut balsa trailing edge fill-in block to fit between the W-l ribs and glue it in place.
  3. Glue the wing hold-down plate to the fill-in block at the notch that you made in "part a" of this step.


  1. Add the 1/4' sq. balsa forward spars to the bottom of the wing.
  2. Sand the leading edge to the bottom contour of the wing as you did in Step 20.
  3. Glue the 3/32"x3" balsa bottom leading edge sheeting in place in the same manner as the top leading edge sheeting. Notice that the center section sheeting must be cut about an inch short at the inboard end. Later, this sheeting will be cut away even further.
  4. When dry. trim the excess top and bottom sheeting flush with the front of the leading edge.


  1. Glue the 1/4"x7/8" balsa leading edge caps to the front of the wing. (Cut the 12" center section cap from a 36" length.) Use tape or pins to hold the leading edge caps flat. Let dry.
  2. Carve and sand the leading edge caps to the shape shown on the plans. Take your time with this step and try to keep the shape uniform along the entire leading edge. You can use the optional Leading Edge Carving Guide (Plate 3) to check the shape at random spots along the leading edge.


  1. Add the 3/32"x1" balsa bottom wing sheeting.
  2. Add the 3/32"x3/4" balsa bottom aileron sheeting.
  3. Use the leftover material from Step 24. for the servo bay sheeting. Make the pushrod exit cutout as shown on the plans then glue this sheeting to the bottom wing surface only.
  4. Glue in all the 3/32"x1/4" balsa capstrips on the wing bottom.


32. Carefully sand the entire wing half until all joints are smooth. Use a large sanding block to avoid sanding down anyone area too much.


Use a deep blade razor saw (such as an X-Acto No. 236) to cut through the top and bottom main wing spars and the temporary balsa spacers at the wing joint.
CAUTION: BE VERY CAREFUL NOT TO CUT OR EVEN NICK THE ALUMINUM JOINER SPARDURING THIS STEP. Even a very small nick in the joiner at this spot may become the starting point for a stress crack that could lead to a structural failure of the spar.
You may now loosen the set screws in the wing joiner channels and remove the outer panel from the center section half. Reassemble the wing parts to check for smooth operation of the joiner assemblies. Any binding or misalignment must be corrected before proceeding.


Repeat Steps 8 through 33 for the opposite wing half.

BUILDER'S TIP: Although it's not shown on the plans, we recommend that you install scrap pieces of lite-ply above and below the front wing joiner channel and joiner spar. This will prevent any possible movement of the aluminum parts.

Completing The Wing Center Section

The center section may at first appear to be overly complex or "overbuilt". You should remember, though, that it not only has to withstand the airloads from its nine·foot wing, it must also bear the brunt of the landing loads. Many of the following steps are required to make the landing gear attachment as safe, strong, and scale as possible.


  1. Sand the inboard and outboard ends of the center section halves bringing the spars, leading edges, and trailing edges flush with the end ribs. Trial fit the center section halves together with the die-cut 5/32" plywood DB-1 and DB-2 dihedral braces. The center ribs should meet flush when the dihedral braces are clamped in place temporarily. The long dihedral braces will automatically set the proper dihedral.
  2. Use slow-drying epoxy glue to join the two center section halves, DB-I, and DB-2. Hold everything in place with clamps until dry. Try for good joints and don't be stingy with the glue during this step! Before it dries, double check that the two halves are aligned perfectly with each other.


  1. Glue the SW-2shear webs to the back of the spar and dihedral braces to finish "boxing off" the spar.
  2. Add the 1/8" sq. balsa spacers to the top spar at the W-1 ribs.


Install the top center sheeting using pieces cut from the 3/32"x3"x30" balsa sheet provided (don't sheet the bottom yet).


  1. Use a razor saw to cut a 3/32" wide slot in the center ribs, just forward of the rear spars, to accept the die-cut plywood DB-4 dihedral brace.
  2. Trial fit DB-4 and trim to size, if necessary. Epoxy DB-4 to the rear spars and the ribs, again using clamps to hold it in place until dry.


REFER NOW TO THE FUSELAGE INSTRUCTIONS, STEP 85, BEFORE PROCEEDING. Several steps in the fuselage instructions actually involve work on the wing center section. Construction must be completed through Step 91 before continuing in this section.


  1. Fit the basswood rear landing gear blocks to the wing by beveling the ends to match at the center where they meet. You will have to cut away part of the SW-2 shear webs that interfere with the blocks. Glue the blocks in place.
  2. Epoxy the die-cut DB·3 dihedral brace to the front of the rear I.g. blocks. Clamp in place until dry.
  3. Reinforce each rear I.g. block with short lengths of 3/4" balsa triangle stock glued to the top of the blocks and SW-1.
  4. Add the die-cut 3/32" x 1/2" x 4" plywood I.g. mount plate to the wing. These plates provide a solid base for the nylon I.g. straps, and should be flush with the surface of the rear I.g. blocks. See the "Wing Rib Cross Section" at W-1 (Plate 3) for more clarity on their position.


  1. Carefully trim the wing leading edge flush with the support blocks to make a seat for the front landing gear block assemblies.
  2. Cut away the exposed portion of the two center W-1 ribs so that they are even with the front notches in the W-1A sub-ribs.
  3. Trim the front landing gear block assemblies so that their inner ends meet at the center with the proper dihedral angle and the outer ends are flush with the W-1A sub-ribs. The I.g. blocks must sit firmly in the W-1A front notches and should also sit flat against the support blocks and leading edge. Epoxy the blocks in place, being sure to use plenty of glue.
  4. Fit the 1/2"x3-1/4"x2" balsa landing gear support blocks between the front I.g. blocks and the forward spar. Glue them in place so that their surfaces are flush with the bottom edges of the W-1A ribs.


  1. Cut out the bottom center sheeting that fits between the front I.g. blocks and DB-3 from scrap 1/8" lite-ply and glue in place.
  2. Add the 3/32" balsa center sheeting to the bottom of the center section.
  3. Glue scraps of 3/32" balsa to the sides of the W-1A sub-ribs to finish off the bottom center sheeting.


Strips of 1/8"x3/8"x10-1/2" lite-ply are provided for stiffening the ribs at the wing joint. This is necessary to keep the ribs from bowing inwards when the covering material is applied and shrunk tight. Cut the rib stiffeners to length and glue them to the ribs, just below the capstrips. See the "Wing Rib Cross Section" at W-2 (Plate 3) for the exact positioning of the stiffeners.


Cut two 2"x19" strips of heavyweight fiberglass cloth from the material provided. (Save the rest of the fiberglass cloth for covering the landing gear fairings.) Apply the strips to the top and bottom of the center wing joint using slow-drying epoxy. You should cut the bottom strip into two pieces to avoid the slots for the landing gear wires. To apply the strips:
  1. Coat the wing center with slow-drying epoxy.
  2. Lay the fiberglass strip on top of the glue.
  3. Holding one end of the'strip so it won't move, "squeegee" the glue through the tape with a small paddle of scrap balsa. Scrape over the tape several times with the paddle to smooth the tape and remove the excess glue.
  4. When dry, sand lightly to remove any rough spots, being careful not to sand into the fiberglass cloth itself.

Finishing The Outer Wing Panels


  1. The die-cut 1/8" lite-ply hatch support fits under the edge of the capstrips and overlaps the forward edge of the servo bay sheeting 1/4". Glue the hatch support in place and add a 3/32"x1/4" balsa strip on the front edge so the covering material has a place to attach.
  2. Trim the 3/32"x3"x4-1/4" plywood servo access hatch as necessary to fit snugly over the hatch support. Drill 1/16" dia. holes through the corners of the hatch into the hatch support. The hatch is held on with four #2 x3/8" sheet metal screws. Be sure to mark each hatch so you can tell later which hatch goes with which wing!


  1. Glue in the 1/8"x3/8" lite-ply rib stiffeners. Don't forget the short pieces just inboard of the aileron.
  2. Sand down the inboard end of the wing panel bringing the spars, leading edge, and trailing edge flush with the side of the W-2 rib.


Saw out the aileron using a razor saw to cut through the ribs. Exactly where you cut is not too critical as long as it's somewhere between the rear spars and the aileron spars. Cut through the W-4 rib on the outboard end of the aileron, then remove and discard the part remaining attached to the aileron. The W-4Asubrib will serve as the outboard edge of the aileron. Use a sharp modeling knife to cut the top aileron sheeting and the temporary spacers on the inboard end.


  1. Trim and sand the back of the wing cutout until the ribs are even with the rear spars. Use a long sanding block to sand just enough to make the back edge flat, as shown here.
  2. Sheet the back of the wing cutout with 3/32" x 1-1/2" x 30" balsa, cut to length. When dry, trim the sheeting to airfoil contour.


  1. Sand the outer end of the wing panel, bringing all of the spars and sheeting flush with the end W-4 rib.
  2. Glue the die-cut lite-ply WTR wingtip rib to the end of the wing.
  3. The fiberglass wingtip can be glued to the wing using epoxy or CIA. Be sure to clean and lightly sand the inside of the fiberglass where the glue will come in contact. Notice that the wingtip overlaps only onto WTR when glued in place. Also notice that WTR does not extend all the way back to the rear point of the wingtip. The small gap that remains can be left as it is or filled with scrap baIsa.
  4. Feather the wingtip into the wing using model filler.


  1. Trim and sand.the front of the aileron in line with the angled, die-cut slits in the ribs.
  2. Add the 3/16" x 1-1/2" x 30"- balsa aileron leading edge.
  3. When dry, sand the aileron leading edge to shape.
  4. Sand each end of the aileron flat.


  1. Glue in the W-4A aileron rib in the position shown on the plans. The aileron rib may need some trimming to slip into place.
  2. The aileron control horn is actually a 90-degree bellcrank. Cut a slot in the aileron leading edge (don't cut the spar!) just large enough for one arm of the horn, then epoxy the horn firmly in place on the W-4A rib. See the "Wing Rib Cross Section" at W-4 (Plate 3) to see exactly how the horn is positioned.


51. Cut hinge slots in the aileron leading edge and the wing cutout to accept the nylon hinges. (See "Hinging Tips" below.) Use four hinges per aileron, in the positions shown on the plans. Trial fit the hinges and aileron on the wing, without glue, to check for smooth operation and proper fit. If there is any mismatch or binding, alter the slots as necessary to correct. The ailerons may be hinged permanently now, or after covering and finishing, if you prefer. Notice that the aileron should be positioned on the wing so that it has an equal gap, about 1/8", at each end. The gap at the leading edge should be 1/16" or smaller.
In many ways, building the wing in one piece will simplify construction. The only drawback is handling and transporting that big "surf board!". Even the size of your workshop should be taken into consideration since you will need to flip the wing over, turn it around, fit it to the fuselage, and even set it aside many times while you work. Think ahead! Having made the decision to build the one-piece wing, it becomes obvious that all of the steps involving the aluminum wing joiners can be skipped over during construction. The other major changes are as follows:
  • DELETE STEP 3. You won't need two W-2 wing ribs at the wing joint because the one-piece wing has no wing joints. When it comes time to place the ribs on the bottom main spar, install only the outboard W-2 rib at the joint.
  • MAINTAIN THE BOX SPAR. Even though the aluminum pieces have been omitted, the main spars still require plywood shear webs at those locations. The JW-2 webs can be used, but the JW-l webs will have to be replaced since they won't be long enough with the W-2 rib having been omitted. Use 1/8" lite-ply for the shear webs. The rear webs can be omitted completely.
  • SPLICETHE LEADING EDGE, SPARS AND SHEETING. The laminated spruce main spars won't require splicing, but the other spars will. Glue the ends of the spars together and reinforce the joints by bridging them with scrap balsa. Place all of the splices for the spars and leading edges towards the outboard end of each wing half. The leading edge sheeting and trailing edge sheeting should be carefully cut and located so that the splices are centered over a wing rib.


Repeat Steps 44 through 51 for the other outer wing panel.

By placing the control horn aft of the hinge line, the aileron will automatically have different movement; that is, it will hinge slightly further up than down. The further aft the horn, the more "differential". On an airplane like the Spacewalker, differential ailerons improve the quality of the turns in flight. The alternate aileron control horn position shown below will give more differential movement than the one shown on the plans, but it's not quite as sturdy. We recommend that you use the horn position shown here if you are building a wing with the "short" (four-bay) ailerons, since it will benefit more from the increased differential than will the longer aileron versions. Many of the new radio systems give the modeler the ability to adjust the aileron differential electronically, making the original horn position more desirable.
One of the difficulties of modeling a homebuilt aircraft is trying to keep up with all of the changes that are inevitably made by the aircraft's owner or designer. In the case of the Spacewalker, the ailerons were the primary focus of early redesign.
Jesse Anglin built the prototype Spacewalker (NI07 JA) with ailerons that spanned the full length of the outer wing panels (eight rib bays). He apparently felt that the ailerons were too long, so he changed the design by cutting the aileron length in half (four rib bays), leaving the chord the same. All full-scale Spacewalker builders, including Maxey Hester of Sig, were notified of the change. Therefore, N107JA is the only example of this design to use eight-bay ailerons.
Maxey flew his Spacewalker (N516MH) with the four-bay ailerons for the first time on September 4, 1987. Jesse Anglin was present that day at Sig Field and also took a turn at the stick. Mildly disappointed with the roll response of the short ailerons, Jesse decided later to make another design change: Split the difference! The six-bay aileron is now standard on the Spacewalker, even though none have been flown with that type of aileron. However, another full-scale Spacewalker was under construction at Sig when this kit was released. That airplane belongs to Hazel Sig and will be equipped with, you guessed it, six-bay ailerons!
We recommend that you build your model with the six-bay ailerons as shown on the plans, even if you intend to duplicate NI07JA or N516MH. Modifying the wing for longer or shorter ailerons should only be attempted by experienced giant-scale modelers. We have flown prototype models with all three types of ailerons and find the six-bay version is the best overall. The only real reason to use the "long" aileron or "short" aileron is perfect accuracy of outline in scale competition.
If you do decide to build the eight-bay ailerons, they must be stiffened by adding diagonal ribs between the existing ribs. Also, the ailerons should be covered with a high-strength fabric, such as Sig Koverall, for additional strength and stiffness. Add another hinge to each aileron, move the servo and control horn inboard one rib bay, and make certain that there is no "slop" in the control linkage which could lead to flutter.
Notice that materials for the eight-bay ailerons are not provided in the kit. However, the four-bay ailerons simply require you to cut off the aileron spars and sheeting to the smaller dimension. Leave the servo and control horn in the position shown, and eliminate one hinge.