Build Skyrocket
March 1965 Science & Mechanics

June 1941 Popular Science
June 1941 Science Popular Science - RF Cafe[Table of Contents]

Wax nostalgic over early technology. See articles from Popular Science, published 1872 - 2021. All copyrights are hereby acknowledged.

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Build Skyrocket

This is the famous RC plane that broke the world's altitude record by climbing 13,320 feet into the sky!

By Maynard L. Hill

President, Academy of Model Aeronautics

Would you like to set a world's record for radio-controlled aircraft? Skyrocket is the current holder of the world altitude record, but it hasn't gone its limit yet! So if you have a yen to try, look this baby over. It's easier to build and fly than you might think.

The present record of 13,320 ft. was set during a 37-minute flight on July 5, 1963. The model had already broken the old Russian-held record of 7,380 ft. in two successive flights to 11,960 ft. and 12,980 ft. at Dahlgren, Virginia, on the previous day, appropriately enough the Fourth of July.

Skyrocket used 14 ounces of fuel during a flight and it was always still climbing well each time it ran dry. I really believe the plane would go to 16,000 and perhaps 20,000 ft. without any special carburetors or superchargers on about 25 ounces of fuel.

Sides of fuselage are built one on top of the other. Use T-pins to hold work in place.

Use a sharp knife to separate frames where they became glued together during assembly.

Install floor aft of wing station as shown. Turn assembly upside down, pin and align it.

In building Skyrocket use a good grade balsa throughout except where other materials are specified. If building for altitude or endurance use the lighter grades of balsa. Double-glue all joints involving pieces cut across the grain. Put on a coating of glue to seal the grain, then let it dry before re-gluing and setting a piece in place.

Glue 1/16-in. sheet balsa to outside of both frames, then sand frames to same shape.

Install 1/4-in. longeron doublers and fire-wall doublers to inside surface of frames.

A 14-oz. condensed-milk can serves as fuel tank. Formers F-2-3-4-5 box it into place.

Fuselage, rudder and elevator. Start by building two fuselage sides, one on top of the other using T-pins to hold them in place.

Proceed using 1/4 x 1/4-inch, 1/4 x 1/2-inch and 1/4 x 1-inch stock as indicated, but do not install L-1 until later. Allow the assembled sides to dry overnight, then remove them from the building board and glue the 1/16-inch sheets to the outside of the structures. These sheets can be held during dry-ing by repinning the glued assembly to the board. When dry, remove from the board, trim off the excess from the sheets and sand the two sides to identical shape. Now separate the two sides where they became glued during assembly.

The sides are then laid on the building board with the 1/16-inch sheet facing down while the 1/4 x 1/4-inch firewall shoulders and the bottom 1/4 x 1/4-inch longeron doublers are installed. When dry, the fuselage sides are joined by gluing formers F6B and F7 in place along with the part of the 1/4-inch floor that runs aft from leading edge station.

Use a template when cutting ribs. Then nail ribs together and sand to a uniform shape.

Pin spar to board and position ribs, then glue on leading and trailing edges of wing.

Center-Section R-1 ribs are held to dihedral gussets by 1/4-in. strips cut at 45° angle.

Bottom leading edge (1/16-in. sheet balsa) is pinned to spar and the leading-edge strip.

Pin wing to board when installing the top leading-edge sheet and webbing between ribs.

Author M. Hill (right) is congratulated by AMA official on Skyrocket's historic flight.

Install cross members aft of the wing next, being sure the fuselage top view conforms to the drawing. Then install the firewall to which the nuts for engine mounting have been previously attached.

The 14-ounce tank shown was made from an empty condensed-milk can, some, 1/8-inch brass tubing and a bit of solder (or you can buy your tank at a hobby shop). The tank is held in place by F2, F3, F4 and F5 which are assembled with the tank glued in place in the fuselage.

Next install L-1, apply the 1/16-inch sheet top and complete the 1/4-inch forward floor using 1/4 x 1-inch pieces with the grain running across the fuselage. Also install the stabilizer incidence shims, and cover the top aft section and the forward floor with 1/16-inch sheet. Now set this assembly aside to dry.

Like the fuselage, the elevator and rudder assemblies are built by pinning them to a board. The stabilizer is made of 1/4 x 1/2-inch and 1/2 x 1/2-inch strips, and the elevator surface is made of very soft sheet balsa. The hinge is made by sewing with dacron or nylon thread. The vertical stabilizer (fin) is built up of 3/8 x 3/8-inch and 1/8 x 3/8-inch strips. The rudder is built up of 1/32-inch sheet and 1/4 x 1/4-inch balsa to allow the hinge pin and tiller bar to be tied with thread to the vertical post.

The rudder tiller bar is bent at right angles and inserted in its bottom bearing first. Then the fixed fin is brought down over the rudder to mate with the top rudder bearing. Glue the fin securely in place. When dry, install the rudder linkage, attach the elevator with rubber bands and install the elevator linkage. The rudder should deflect about 20° to 25° left and right and the elevator about 15° up and 10° down.

Install the antibuckle strips and landing-gear hooks and finish installing 1/16-inch sheet on the bottom. Also install 1/8-inch doublers in the wing mount area. Sand corners well, and when dry put on two coats of clear Butyrate dope. Put Celastic (a plastic which softens when dipped in dope thinner and hardens to a tough film when dry), or fiber-glass reinforcement over the firewall so that it reaches about 1/2 inch around the sides and top. Also put Celastic patches over the wing and tail dowel regions. Cover with nylon or silk directly over the sheet balsa and paint with two more coats of clear dope and the color dope of your choice.

Craft Print Available

Full-size plans for building Skyrocket may be obtained by ordering Craft Print No. 358. Send check or money order for $5 to:

Craft Print Dept., Science & Mechanics, 505 Park Ave., New York, N. Y. 10022.

Wing construction. Construction of the wing is simplified by the use of a flat-bottomed airfoil. First build the spars by pinning them to the building board. When dry, join them with the dihedral gussets. Now pin one side of the spars to the plans and slide all R2 ribs onto this side in a vertical position. Install trailing and leading edge strips and then ribs R1. When dry, remove from plan and repeat for the other side of the wing. Sand the leading edge strip to contour and install 1/16-inch sheet to bottom surface.

Now repin half the wing to the board and install the top 1/16-inch sheet and webbing between the ribs. This operation forms the D-tube out of the leading edge and makes a rigid structure that can later be doped without warping. When thoroughly dry, repeat the D-tube construction on the other half of the wing. Cut off the triangular section at the tips of the trailing edge and move it forward as shown. Sand the three tip ribs to conform to the new trailing edge.

Install the tips and the second leading edge strips. Sand smooth and paint with two or three coats of clear Butyrate dope and apply a Celastic strip over the center joint. Cover with silk or nylon.

Covering is best done by using four panels of material, one each for the top, bottom, right and left sections. Use Butyrate clear dope for cement. Wet one of the panels with water and stretch it loosely over the structure. Have a wet sponge handy to keep it damp. Paint through the material along the center chord-line. Allow it to dry tacky at this end and then stretch the panel span-wise and attach it to the tip at the other end by painting through the material.

Now paint through the leading and trailing edge areas and stretch the material chord-wise. Trim excess with a razor blade and repeat on the other panels. Paint again.

Install the .56 or .59 engine and throttle linkage, then check out all equipment with the engine off and with it running.

For information on setting up record attempts for model planes, write Academy of Model Aeronautics, 1025 Connecticut Ave., Washington, D.C.

Materials List - "Skyrocket"

IMAG HERE

Above materials are all available from any good hobby shop.

Radio Equipment

A Sampey Command Control 404 System was installed in the original Skyrocket. Detailed descriptions of this $390 system may be obtained by writing Sampey Co., 1607 Forseyth Rd., Orlando, Fla. Many other RC systems capable of operating Skyrocket are also available. They range in price from $60 (single channel) to $500 (4┬Ěchannel proportional). Most are available through Ace Radio Control, Box 301, Higginsville, Mo. The larger hobby shops also carry a representative inventory of these systems.

 

 

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