Skybolt (oz7537)

About this Plan

Sig Skybolt. Radio control scale model of the homebuilt Steen Skybolt, for .45 - .60 power. Discontinued kit from SIG.

Quote: "LaMar Steen's homebuilt Skybolt is not only a great looking airplane but a practical design as well. There are no machined parts and a welding torch and ordinary shop tools are sufficient to construct it. The prototype was built by LaMar's students in the Aerospace program at Manual High School in Denver - a fact which will help clarify the lettering on the decal in this kit.

Full symmetrical wing sections are used to aid aerobatic characteristics and the structure is stressed for 9 G's plus and 8 G's negative. The top wing span is 24 feet and the lower span is 23 feet. One quality that has made it so popular is the reasonable size of the cockpits. An information pack on the Steen Skybolt with 3-view can be obtained for $2.00 from Steen Aero Lab, Inc., 15623 DeGaulle Circle, Brighton, Colorado 80601.

ABOUT THE MODEL Our version of the Skybolt was designed with easy building and good model flight characteristics in mind and the exact scale outlines have been modified. It is primarily intended for the NSPA-AMA biplane stunt event and for sport flying. However it can be used for Sport Scale events if desired. In this connection it should be noted that the available 3-view is not quite like the actual airplane in that a different shape and style of cowling is shown so it is recommended that pictures alone be used as a scale presentation for judging. AMA Sport Scale rules do not require a 3-view for competition - photos only may be used if desired.

It's common with homebuilt's for some component shapes to vary from plane to plane depending on how the individual builders happened to bend the tubing. The tail surfaces on Skybolts are an example of this artistic expression. We used the general shape shown on the Steen three-view and if you wish to emphasize the Sportt Scale aspect, be sure and check photos of the particular Skybolt example being copied for exact shape.

The color scheme of the model was taken from the markings of LaMar's airplane as it, was originally painted. He has since redone it in a more complex pattern with air brushed edges between the colors, while his first version needed only masking tape.

Hale Wallace painted his Skybolt pre-production model like his full-size Skybolt. This is a colorful arrangement but requires more masking to reproduce the checkerboarded under-surfaces. An alternate decal is available with stars, license numbers and the Skybolt name for the cowl to duplicate his airplane.

Hale used a more elaborately shaped cowling on his Skybolt, as have some other home builders of the design. The fairing behind the spinner and the lower scoop can be made from balsa. Glue balsa to the cowling plastic with Sig-Ment. Paint the balsa parts with Sig Sanding Sealer to fill the wood grain.

Single or Double Ailerons? The original model used single ailerons on the lower wing to keep the linkages to the servo simple. The installation was very effective, gave good response and as rapid a roll rate as desired. The complications of hooking up the double ailerons are not worth the trouble for sport fliers the single ailerons are more than adequate. As a matter of fact, the single aileron set up can give a good account of itself at a contest. For high level competition and expert fliers the double ailerons will probably be desired. They provide maximum control leverage and a very rapid roll rate for performing complicated free-style maneuvers.

Muffler Installation. Large chamber type mufflers should be located completely outside the cowl on an extension pipe. The Du Bro Muff-L-Aire or similar stack-type mufflers have a neater appearance. These work well if the plates are taken off and varnish and carbon cleaned away occasionally..."

This good scan was posted up on the HPA site by Cavaliere. I took that scan and spent maybe 2 hours cleaning it up, removed all the background noise, removed the paper creases, also darkened the ink lines slightly for better clarity, too.

See RCGroups thread here http://www.rcgroups.com/forums/showpost.php?p=27312808&postcount=21 for more info on the old SIG kit.

Update 18/03/2016: Added extra sheet showing hand-traced parts, thanks to mjb.

Update 23/06/2018: Added build manual, thanks to GT.

Update 11/12/2024: Added kit review from RCM&E June 1992. thanks to RFJ.

Quote: "SIG Skybolt. David Matthews builds La Mar Steen's beautiful bipe.

The name Skybolt is one that suggests power combined with beauty and that is just what the Sig Skybolt is. The model has been designed as a stunt/sport scale machine from La Mar Steen's full size homebuilt prototype version. The exact scale outlines of the model have been slightly modified to accommodate the modellers needs and it utilises a fully built-up structure which is a pleasure to piece together. As all modellers and full size enthusiasts know, biplanes have a certain extra character, something that Sig's Skybolt oozes in. Designed for the larger engine sizes, I chose an ASP .61 ABC which was to prove more than adequate for the task in hand. With four function R/C at the ready I began the construction process.

The box of bits is cellophane wrapped, this I would guess is to ensure that all the parts packed in the factory arrive at their new home at the same time without the need for the purchase of more balsa. A big plus for this kit. Opening any kit, for me, is like Christmas all over again because you never know what to expect next. The mass of wood and ply has to be seen to be believed, and not just for it's quality but also for the sheer precision of the pre-cut parts.

The thing that stands out most is the one piece plastic turtle decking and cowl parts, all of which are of impeccable quality, another hallmark of the manufacturer. As I said the wood chosen is first rate with correct densities used in all the right places. Typical, but very important, are the safety tips about the operation of models that are printed on the box, plans and the instruction booklet of this Stateside kit.

The instruction booklet is 36 pages in size, though not all of this is text. There are a lot of black & white photographs to help with the scale detailing should one wish to do so. As this is an American kit, a dictionary to define some of the American products wouldn't come amiss as items such as 'SIG-MENT' are probably not as common in this part of the world.

The accessory packs are full of good quality parts and added to this, Sig have included the items needed for the construction of either the two or four aileron version models, one with torque rods and the other with bell-cranks. As the latter was preferred, those torque rods will be installed in a future model. All that is left to supply is the tank, wheels and preferred covering medium. No canopy is supplied, a piece of acetate sheet being used for a windshield.

Let's get started: Referring to the instruction manual, the first recommended stage is the fuselage construction which is sheer simplicity due to the fact that the sides, while looking like a stringered structure are in fact sheet, with the stringer added at a later stage. Most of the materials used here are 1/4 in sq balsa strips with several ply formers allocated for strength. The use of a jig would be of great benefit but as one was not available I made up my own.

Routed hardwood, similar to that of u/c blocks, are used to hold the cabane struts to the fuselage. These struts are made from 1/8in preformed piano wire which I chose to silver solder together to ensure that parting of these components was not likely to happen.

That plastic fuselage top is installed only when the tail assembly has been permanently fixed into position. Balsa stringers are added to the sheeted sides and on the bottom of the fuselage, ensuring that the spacing is equal on both sides.

The cowl comprised of three parts that needed very little work in order to ensure that a good fit between it and the body. These three pieces were stuck together using M.E.K. in order to fuse the plastic, thus ensuring a stronger joint. The same method was used to join the wheel pants as they also come in two parts.

When these structures had set I gave them a good rub down using 400 grade wet 'n' dry in order to remove those nasty imperfections which can destroy the final appearance of any model. These were put aside in order that the rest of the model could be built.

On to the cabane struts; in the instruction manual there are two methods which can be employed. I chose to make up the struts using the method devised by a modeller in the States by the name of Jerry Smith. This method allows for the removal of the struts at the covering/painting stage..."

Supplementary file notes

Parts (tailplane outline and interplane struts).
Manual.
Review.

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