1. CA adhesive can be used to assemble the cowl. Hold the plastic joiner in place on the inside of one cowl half. Leave half of the joiner strip extending over the edge so as to tap onto the other cowl half when it is attached. Flow a few drops of adhesive under the edge of the strip. It will spread along the seam by capillary action.Squeeze and hold together any area of the strip that is not down tight against the cowl. Be careful not to let the adhesive get under your finger. Let dry, then hold down the other half and glue it in the same manner.Let dry and even up the back of the cowl with a sanding block.
  2. Use the full-size drawing for a pattern to mark out the openings in the cowl. Cut out the openings with a sharp knife or a Dremel tool with a drum sander attachment. Bring the cutouts right up to the lines using small sanding tools or a fine-tooth file. You will have to make small cutouts for the rocker arm covers if you are using a single cylinder engine.
  3. Make a cutout in the front of the cowling for the engine's prop shaft. The cutout should leave plenty of clearance for the front end of the engine, but should be smaller than the 3" spinner diameter.


  1. With the engine mounted, tape the cowling into its final position on the fuselage. Check its fit by temporarily placing the 3" spinner on the prop shaft. When viewed from the side, the spinner should blend perfectly into the top curve of the cowling. Be sure to leave at least 1/16" clearance between the spinner and the cowling.
  2. Drill the pilot holes through the cowling and into the fuselage sides in six places using a 1/16" drill bit. The top holes on each side should pass directly through the spruce longeron. The bottom hole on each side should also pass through the bottom spruce piece of the fuselage main frame. Remove the cowling.
  3. Redrill the six holes in the fuselage with a 11/64" drill bit for the threaded inserts. Using the 4-40 x 1/2" panhead screws, thread the screws into the insert and place a small drop of 5 minute epoxy or slow CA on the insert. Be careful not to get any glue on the threads of the insert or the exposed threads of the screw. Screw the insert into the fuselage until the insert is flush with the fuselage side. When the glue dries the screws can be removed.
  4. Redrill the holes in the cowling with a 1/8" drill bit.


95. Trim out the left and right plastic dummy engine cylinders using a knife or scissors. Use a sanding block to smooth the edges, leaving a 1/16" gluing flange around the cylinders and exhaust pipes. The cylinders can be glued to the cowling before or after painting using thin cyanoacrylate adhesive. Locate the cylinders as shown in the photo.

NOTE: Use the same dimensions shown here for the dummy engine on the left side of the cowling. Notice that, when viewed from the top, the right-hand cylinders will be staggered aft of the left-hand cylinders, just as they are on the full-scale Continential engine.


Cut out the cylinder shroud pattern and tape it to the plastic molding. Mark around the pattern and the back of the molding, remove the pattern, and carefully cut out the cylinder shroud. Flip the pattern over and use it to mark the other side of the molding. The shrouds may need a little trimming for a perfect fit on the dummy cylinders. The top edge of the shrouds should be in contact with the cowling, just above the cylinders. The back flange of the shrouds should be pressed up against the back cylinder.

Wing Straps

Two pieces of 1/64"x7/8"x36" plywood are provided for optional wing straps to simulate the aluminum straps used by Maxey Hester on his full-scale Spacewalker II. The straps may be omitted from the model. Wrap the strips of plywood completely around the leading edge and cut off any excess at the trailing edge.

Fuel Cap Cover And Compass Assembly

The teardrop-shaped fuel cap cover should be trimmed from the plastic sheet leaving a 1/16" to 3/32" flange around the perimeter. The flange gives plenty of gluing surface and is scale. For best appearance, paint the cover separately and glue it to the finished fuselage with CA.

The molded plastic compass is assembled in a fashion similar to the plastic shock springs. Cut out the halves as close to the base as possible, then sand each piece until they match and the compass assembly appears round when the halves are held together. Glue the halves together using CA, dope thinner, or MEK as you did before. The "bulge" at the bottom of the compass was necessary for molding purposes and must be trimmed off after assembly. Paint the compass flat black before gluing it to the painted fuselage.


It is generally easiest to mount all of your radio equipment and pushrods in the model before covering and painting. Once the initial installation has been made and all the bugs worked but, you can remove the radio system and then reinstall it when the airplane is finished.


Mounting Servos in the Fuselage

The fore and aft location of the servos is generally not critical for balancing purposes. The servos in the photo model were mounted towards the rear of the radio compartment to help keep the pushrod lengths as short as possible.
Use wood screws to mount your servos directly to the hardwood servo rails. Cut two servo rails from the 3/8" sq. spruce provided in the kit and epoxy them across the inside of the fuselage with the proper spacing for your servos. Glue scrap pieces of balsa to the fuselage sides around the ends of the servo rails so that they can never come loose in flight.

Elevator Hookup

Instructions for assembling the fiberglass elevator pushrod are on the plans (Plate 3). Use 3/32" dia. music wire and a 4-40 solder clevis (supplied in the kit) at the servo end of the pushrod. Notice that after the fuselage is covered, a pushrod exit slot will have to be cut into the fabric. We suggest that you duplicate the full-scale practice of reinforcing around a cutout in the fabric using a thin plastic reinforcement cut from scrap ABS. Use the pushrod exit reinforcement pattern. Apply it to the covering by brushing clear dope on the fabric and pushing the reinforcement onto the wet paint. When dry, the plastic should be firmly bonded and the fabric inside the ring can be cut out with a sharp knife.

Rudder Hookup

A 4-40 threaded rod and clevis are supplied to serve as the rudder pushrod between the rudder servo and the tiller bar. Make a 90 deg. bend in the pushrod to engage in one of the inner holes on the tiller bar and use a wheel collar or soldered washer to permanently hold it in place.
Instructions for mounting the tiller bar and hooking up the rudder cables are on the plan (Plate 3). You can check your rudder hookup by watching its response to commands from the transmitter. If the rudder doesn't want to return back to neutral after letting go of the stick, the cables may need more tension or there is a bind somewhere in the system. Small discrepancies around neutral (1/16" or less) are okay, but larger variations are unacceptable. Be certain to periodically check the tension of the rudder cables as they may tend to loosen after several flights.

Throttle Hookup

All the materials to assemble a flexible-cable throttle pushrod as shown below are supplied in the kit. It should be supported at the servo end so that it is aimed directly at the output arm on the throttle servo. Cut a support block from scrap balsa and glue it firmly in place against the fuselage side. Epoxy the nylon outer tubing to the support block. Route the cable so that it makes as few curves as possible and provide at least one support between the servo and the firewall to keep it from buckling or flexing under load.


Aileron Hookup

In addition to a fifth servo, you will need to purchase two extension cords, a "Y" harness, and a single Horizontal Servo. All radio manufacturers have these items available as stock equipment. It is best to keep the extension cords as short as possible, 16" should be long enough when the "Y" harness length is added to it. Excessively long cords have been known to cause radio interference under certain conditions.

Temporarily fit the 1/8" die-cut Lie-Ply servo mount between the W-3 ribs, but don't glue it in place yet. Mount the servos to the Horizontal Servo Tray with four screws that are supplied with the tray. Now drill two 1/8" dia. holes through the tray, one on either side of the servo. These holes will allow the installation and removal of the servo tray with 4-40 x 3/16" macine screws.

Position the tray on the plywood servo mount in the wing, making sure that the servo arm is lined up with the slot in the servo bay sheeting. (Keep in mind that both servos must be located towards the outer end of the wing so that the ailerons will work properly when plugged into the "Y" harness.) When you have the servo lined up, use a pencil to mark the plywood mount at the two holes in the plastic servo tray.

Remove the servo tray and servo mount from the wing. Drill the plywood servo mount at the marks with a 9/64" drill bit, then glue in two 4-40 blind nuts. Reinstall the servo mount back in the wing, this time gluing it in place. Reinforce the glue joints with two short lengths of 3/16" sq. balsa.

Receiver and Battery

Wrap the receiver and battery pack separately in foam rubber (such as SIGRF240), held on with rubber bands or tape, to protect them from engine vibration. The best location in the fuselage for the receiver and battery can't be determined until your model is completely finished. Shifting these components fore or aft can help get the model balanced properly. Be certain that both are secured into position so that they can't shift around in flight.

The receiver antenna can be run out of the bottom of the fuselage and taped at the aft end. This will expose the antenna without making it too conspicuous. It may also be mounted inside the fuselage in a long piece of nylon tubing glued into one of the corners. The switch and charging jack can be mounted on PT-1 in the cockpit opening for easy access.

WARNING - DANGER! -Important: Read These Warnings:
  • Do Not fly control line or towline models within 300 feet of electric power lines. Instant death from electrocution can result from coming near them. Direct contact is not necessary.
  • A model airplane motor gets very hot and can cause serious burns. Do not touch the motor during or after operation.
  • Keep clear of the propeller. It can cut off a finger or put out an eye. Make sure the propeller is securely fastened in place and is not cracked.
  • Model airplane fuel is flammable and poisonous. Take the same precautions while transporting and using it that you would with a can of gasoline or a bottle of poison.
  • Remember that it is possible to lose control of a model airplane. Do not fly in locations where the model may hit people or damage property if loss of control occurs.
  • Check your model and equipment regularly to insure it is in safe operating condition.


There are many engines available today that are suited for the Spacewalker II, and each one has features that will require some amount of thought and engineering. Builders also have their own preferences regarding mufflers, engine mounts, etc., so nearly every Spacewalker II model will have something of a custom engine installation.


When choosing an engine, keep in mind the type of performance that you wish the model to have. If you want great aerobatic capability and vertical performance, use an engine towards the upper end of the recommended size range. If you want more scale-like flying qualities, engine size towards the bottom of the range may suit you better. Keep in mind that even engines at the bottom of the range will put a Spacewalker II through most aerobatic maneuvers.

The engine shown here is a Saito 120, mounted inverted on a Dave Brown glass-filled mount, #1204. The Saito 120 can also be side-mounted (cylinder horizontal), but it will stick out of the side of the cowl and interfere with the dummy engine cylinders. It would also need a higher fuel tank location, requiring you to cut into the plywood top, which is not recommended.

This particular engine installation has worked well without any on-board ignition system. However the reliability of most glow engines will be improved by on-board "glow", and the Spacewalker II is certainly capable of hauling the extra weight. An on-board ignition system uses a battery carried in the aircraft to keep the glow plug "hot" at all times (or just at low throttle, depending on the system.) On-board glow will also allow you to start the engine without hooking up an external battery. On this installation, a starting battery with a long extension is passed through a hole in the bottom of the cowl to engage the glow plug.

Most engines will require an extension on the needle valve to bring it to the edge of the cowling so that the mixture can be easily adjusted. We used a length of brass tubing, soldered to the needle valve at one end and soldered a 4-40 socket head bolt to the other end. A 4-40 balldriver is used to adjust the needle through a small hole in the cowling while the engine is running. The socket head/balldriver technique works especially well because the tool doesn't want to vibrate out of place like a screwdriver might.

Another Spacewalker II prototype used an O.S. 120 Twin for power. This is a twin, four cycle engine that provides flawless performance and reliability. Enough power to put the Spacewalker II through all the aerobatics that most sport pilots are capable of performing!

As you can see, custom exhaust extensions were fabricated for each cylinder from brass tubing, and routed to the air exit opening in the bottom of the cowl. This engine uses the same type of socket head needle valve extension described earlier.

The main things to remember when installing your engine are generally common sense, but are listed here to help those builders with little experience.

  1. Make certain that the engine is mounted solidly and all bolts are tight
  2. Use a muffler! The exhaust tubes should be routed through holes in the bottom of the cowling or out the cooling air exit. Long extension tubes must be braced or clamped to the structure to avoid damage from engine vibration.
  3. Provide a simple means of adjusting the needle valve setting without having to remove the cowling. There should also be easy access to fuel lines, glow plus, etc.
  4. Be sure that no parts of the engine, exhaust system, or spinner come into contact with the cowling.


Use only those propellers recommended in the instructions supplied with your engine.


The 3" dia. Tru-Turn spinner is shown on the plans. It has a true scale shape and diameter. Of course, other spinners may be used, but they may not have the correct scale appearance. Tru-Turn spinners are machined from aluminum bar stock and are of a very high quality. Also be sure to get the proper Tru-Turn prop nut assembly to fit your engines.



For the strongest, most durable, and most realistic finish on your framed-up Spacewalker II, we recommend that it be covered with some type of fabric, such as Sig Koverall. No matter what you choose for covering material, it will not conceal a rough framework. Be sure all surfaces are sanded smooth before proceeding.

The manufacturer's directions for applying iron-on coverings are packed with the material. Follow these closely, for different types of material have different iron temperatures and techniques of application. The rest of these instructions describe the use of Sig Koverall.

Koverall is a polyester-base, heat-shrinkable, synthetic fabric much like the covering used on full-scale aircraft such as the Spacewalker II. Its toughness makes it ideally suited to giant-scale model aircraft - we've used it successfully on all of our Spacewalker II prototypes. It is relatively low cost and will add a great deal of strength to the model's framework. It can be applied to the model using dope or Sig Stix-lt, a heat-activated adhesive.

Surface Preparation

Whichever application method is used, you should first brush two coats of clear dope onto the framework wherever the covering material makes contact (even the capstrips on the wing). If you plan to use dope for the entire finish, use Sig Supercoat (butyrate dope) for the first two coats. If you plan to use enamels or epoxy colors, use Sig Nitrate dope. Lightly sand after each coat to remove any raised grain or fuzz.

Applying Koverall With Dope

The bottom of the wing is a good place to start covering. Cut a piece of material about an inch larger all around the panel, with the grain running spanwise. (The grain of woven materials runs parallel to the finished bias edge.) Lay the Koverall on the wing, pulling out any major wrinkles. Koverall shrinks up considerably under heat - there's no need to worry about such things as packaging fold creases because they will come out easily with the iron. Brush clear dope around all the edges. This will soak through the fabric and adhere it to the dope already dried into the framework. Allow the dope to dry before trimming off the excess material with a sharp razor blade. Check for any rough edges or places that are not stuck down properly and apply more dope, let dry.

Applying Koverall With Stix-It

Directions for applying Koverall with Stix-It are on the can. The basic procedure is to apply Stix-lt around the edges of the framework where you want the covering to attach. When dry, the fabric can be ironed-on around the edges where the Stix-It was applied.

Shrinking and Sealing Koverall

After both sides of a surface are covered, shrink the Koverall evenly with an iron or hot-air gun (read the Koverall package instructions). The fabric can now be sealed with three or four coats of clear dope. Thin the dope until it brushes on easily and flows out smooth (about 25% to 30% thinner). The first coat should be applied sparingly to avoid puddles underneath the fabric. The second coat will seal most of the pores of the Koverall and from then on running through will not be a problem. Sand the model VERY LIGHTLY with FINE sandpaper after the second coat is dry. The next two coats will completely seal and begin to fill the weave of the fabric. When dry, sand again. Your Spacewalker II is now ready to be finished with its colored paint scheme.

Some Notes on Covering the Spacewalker II

The covering on the wing can be extended to cover the entire ABS wingtip. This will add a little strength to the tip and provides a more consistent surface for the paint.

The fuselage can be covered two different ways. The easiest method is to use four separate pieces of material; one for the bottom, two for the sides, and one for the turtledeck, applied in that order. The turtledeck piece should end about halfway on the small dorsal fin (R-6).


The covering material for the fin is then overlapped 1/4" onto the turtledeck fabric. This does leave a seam, but it can be mostly hidden by applying a few extra coats of dope in this area and sanding lightly. This method was used on the photo model and the seam is hardly noticeable.

A perfectly smooth fin fillet can be achieved by covering the fuselage with three pieces of material; one for the bottom and another two, each covering one fuselage side, half the turtledeck, and one side of the fin. This method is a little trickier, but it does produce fewer seams. Don't shrink the fabric until all of the pieces have been firmly attached to the framework. No matter which way you cover the fuselage, the fabric on the fin should attach to the first 5/16" sq. balsa rib up from the bottom.

Paint Schemes

The eye-catching "spike" paint scheme used on Maxey Hester's yellow and red Spacewalker II was painted with Ditzler's Durathane. Maxey's colors can be duplicated using Sig Supercoat Dope in the formulas to the right.

Paint Formulas to Match N516HM

Of course, Sig Cub Yellow and Sig Light Red can be substituted if you aren't interested in a perfect color match. We've found that a light coat or two of Sig White dope provides an even base for the colored dope and actually reduces the total amount of paint necessary. It is generally better to apply light colors first, followed by darker trim colors.

Maxey's original full scale paint scheme was red and white and was painted with Sig Supercoat Light Red and White.

The paint scheme patterns given on the plans can be used for either aircraft. The patterns can be cut (or traced) from the plans and positioned directly on the airplane. Draw around the pattern lightly with a soft lead pencil, remove the pattern, and mask off the surface using the lines as your guide. We use "low-tack" drafting tape to mask off paint schemes on our models. Seal the edge of the tape with a coat of clear dope before applying the trim color. If you have used Sig Supercoat Dope throughout, a final coat of clear over the color paint will add a nice gloss to the finish. Do not try to mix different brands of paint. Use Sig products from the start and follow the instructions that come with them carefully for best results.

The pin stripes on both airplanes really help to set off the colors. We used 1/16" wide tape on the model and it looked just fine even though it wasn't scale.

Other homebuilt Spacewalker IIs should be appearing shortly all around the country with other paint schemes. If you are not particularly interested in scale competition, you will probably want to come up with your own design.

Painting the ABS Plastic Parts

The plastic parts should be sanded to remove the gloss before they are painted. Use only 220-grit or finer sandpaper. We recommend that the plastic parts be painted with Sig Supercoat Dope for best results. Sig Plastinamel, Hobbypoxy, K&B Superpoxy, and Dulux (automotive) enamel have also been proven compatible with ABS plastic and can be used if desired. K&B primer may also be used for a smooth undercoat. Do not use other paints, dopes, or finishes without first testing to make certain it is compatible with the plastic.
CAUTION: Do not try to cover the ABS plastic parts with Monokote or other iron-on types of covering material. The heat may melt and distort the plastic.

Decal Application

All the decals necessary to duplicate N516HM are supplied in the kit. Notice that the curved Spacewalker logos have been pre-aligned with the little spacemen so that they can be applied in one piece.
Model fuels are hard on decals. Even if you are using no nitromethane in your fuel, the oil can still get under the decals and loosen them. Try to direct your exhaust out to an area without decals. Coating the decals with auto paste wax will help protect them, but the wax must be replaced at regular intervals. If needed, replacement decals are available from Sig.
  • Cut out the decals with a pair of sharp scissors. Leave about 1/32" to 1/16" of clear edge around the decal. Round the corners as you are cutting.
  • Wet the surface on which the decal will be placed with soapy water (use dishwashing detergent).
  • Place the decal on the model and squeegee the water from underneath with a balsa paddle and allow to dry.
This procedure will prevent air from being trapped underneath as is possible when the decals are applied dry.


Interior Detailing

Some modelers enjoy spending many hours providing their models with intricate detailing, while others spend no time at all. The cockpit area of your Spacewalker II can be given as much scale detailing as you wish, however no materials (except for the plywood instrument panel) are provided in the kit. The following recommendations will add immensely to the overall impact and realism of the model without taking too much time.

Paint the Interior
The wood inside the cockpit must be protected with several coats of clear dope. Once it is sealed, some flat black or gray painted on the exposed areas will help give a less obtrusive appearance.

Instrument Panel
Maxey Hester used a plywood panel in their airplanes, so the die-cut 1/16" plywood instrument panel provided in the kit will appear very realistic when finished with several clear coats of dope or varnish. Several manufacturer's make 1/4-scale aircraft instruments that can be fitted to the panel to give your model an added touch of realism. After painting and adding details to the panel, it can be glued permanently in place.

A few manufacturer's also produce 1/4-scale pilots that are easily painted and mounted to the plywood top. Notice that the pilot should be placed well towards the back of the cockpit opening.

Pre-Flight Checkout

Be certain to range check your radio equipment according to the manufacturer's instructions before attempting test flights. A lot of problems can also be avoided if your engine has been well broken-in and the idle adjustment perfected on a test stand or in another airplane before installation in the new model.


For test flights, the following are suggested:
ELEVATOR 3/4" UP and 3/4" DOWN
AILERON 1" UP and 3/4" DOWN

The control measurements listed above should give full aerobatic capability if your Spacewalker II is properly balanced. Test flights may indicate a need for more or less movement, depending on individual model performance and personal preference.

Balance your model somewhere in the C.G. (Center of Gravity) Range shown on the plans. For test flights it is better to balance in the forward portion of the range than in the rearward portion. Add weight to the nose if necessary - trying to fly with the C.G. too far back is much more dangerous than the slight increase in wing loading caused by adding lead to the nose!


The Spacewalker II has proven to be one of the most exciting models that we've ever flown. Although it will perform the full range of aerobatic maneuvers, it will settle down for slow, stable landing approaches and touchdowns. It's a fun and easy aircraft to fly, but it is not a basic trainer. Do not attempt to fly your Spacewalker II unless you've logged some flight time on other low-wing aircraft. Have an experienced pilot assist you, particularly on test flights.

In the air, you will find the Spacewalker II to be very smooth and stable. It's aerobatic capabilities will definitely please any sport pilot. After the model has been trimmed and you are more familiar with its flying qualities, you may want to experiment with slight changes in control surface travel and balance point until the model flies and reacts just the way you like it. Advanced pilots who are striving for maximum realism and smoothness should "coordinate" their turns by adding a small amount of rudder at the same time, and in the same direction, as the aileron. Many of the newer radio systems offer a "coupling" feature which will automatically deflect the rudder slightly when you use the aileron stick. We have used this feature successfully on our Spacewalker IIs. The proper amount of rudder movement is about 1/2" each direction with full deflection of the ailerons.


When the time comes to land your Spacewalker II, remember to keep your control inputs smooth and gentle to avoid overcontrolling. When you are certain that the model will make it to the runway (even if the engine quits), bring the throttle to full low and concentrate on keeping the wings level during final approach. Slow the model down during the entire approach by slowly feeding in up elevator. Just before the model touches, flare the landing by carefully feeding in more up elevator. Hold the model just inches off the ground until your elevator stick is pulled all the way back. The Spacewalker II should settle down to a perfect "threepoint" landing with a short rollout. Taxi back slowly and graciously accept all the praise offered by onlookers. Your Spacewalker II will surely be the hit of the flight line!


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SIG MFG. CO., INC............Montezuma, Iowa 50171-0520
In use of our products, Sig Mfg. Co.'s only obligation shall be to replace such quantity of the product proven to be defective. User shall determine the suitability of the product for his or her intended use and shall assume all risk and liability in connection therewith.