Vultee BT-13 Valiant (oz11157)

About this Plan

Vultee Valiant. Rubber scale model military trainer.

Quote: "LATEST in the series of Vultee basic trainers used by the United States Army Air Corps which began auspiciously with the BT-13, the Valiant now serves as the BT-13A or LT-15, depending on engine installation. Powered by either Pratt & Whitney or Wright radial engine developing 450 hp, the Valiant has a top speed of 182 mph and a service ceiling of 21,000 feet. It has a wingspan of 42 ft, is 28 ft 7 in long, and measures 9 ft 1 in in overall height.

This fine training plane, designed expressly for the USAAF, is the backbone of our Air Cadets' basic flight training; practically every one of our boys who sprouts wings on his tunic soloed in this plane. The Valiant is ideally suited for rough training routines. Being extremely rugged and stable, Cadets with 'air sense' find little difficulty in learning to fly and solo in one of these ships even with 450 hp. mounted in the nose.

Incidentally, the author got a rather odd 'kick' out of modeling this basic trainer, for being an Aviation Cadet in Uncle Sam's Enlisted Reserve, he expects to be sitting in the cockpit of a BT-15 very shortly.

The model has been accurately reproduced and is worthy of any effort expended on its construction. It is not only attractive as a display model but is also a speedy, stable flier. Because of its excellent proportions it is ideal for scale endurance meets.

The model Valiant is simply constructed in the conventional manner. While the test ship was built of half balsa and half pine, the plans call for all balsa which is of course the best material. However it is readily adaptable to construction using slightly heavier white pine and basswood now being sold at most model shops. All wood should be selected carefully to assure the lightest, strongest structure possible. In the process of assembly all frames should be made with accuracy and each joint cemented firmly.

FUSELAGE: Begin construction by making the keel pieces. Trace top and bottom outlines of the side view to get the correct shape; the bottom keel is a continuous piece extending from nose to tail, and the top keel is two separate pieces. Average depth of the keels is about 3/16; they are cut from 1/8 sheet balsa. Bulkheads are shown full size on the plan and they are cut from 1/16 sheet except bulkheads A and B which are 1/8 sheet balsa. Two of each are required. You will notice that the bulkheads are marked where the stringers run; they are notched during the actual construction to insure accuracy. Cut the keel notches however and merely mark the other positions.

Pin the keel pieces into position over the plan and begin actual fuselage assembly. Temporarily cement a piece of 1/8 x 3/16 balsa between the top keels to join them at the opening created by the cockpit. Cement half the bulkheads to their respective positions and when dry remove from the plan and attach the remaining ones to the other side. Align the bulkheads accurately so they are exactly perpendicular to the keels. Cut notches in the bulkheads and insert the 1/16 sq stringer along the thrust line, being careful not to pull the fuselage out of line. Place the remaining stringers, cutting the notches as required with a sliver of a razor blade. Once a stringer is attached to one side, always place another in the corresponding position of the other side. After the stringers are all attached, the temporary brace at the cockpit is inserted.

The engine cowl is made of 1/16 sheet cemented between bulkheads A and B. Note that the sheet is laid on top of the stringers to cause a slight rise. Make a paper pattern of the cockpit shape and cut the 1/32 sheet balsa to the required shape. Pins and rubber bands will keep the sheeting in place until cement is dry. Cover the section behind bulkhead D with 1/32 sheet to form the turtleback. The cowl front is made from three discs of 1/8 sheet balsa which are cemented cross-grain. The discs have the centers removed to the extent indicated on the plans. Attach the unit to the first bulkhead A and when dry roughly cut to shape. Finish by carefully sandpapering the cowl and discs to required shape. The nose plug is hardwood. The removable nose plug is made to fit snugly into bulkhead A.

TAIL SURFACES: Construction of the tail surfaces is easy. Both the stabilizer and rudder are built in a similar manner. To obtain greater strength the stabilizer is built in one piece. All sizes are given in the plans. The tips are soft 1/8 sheet balsa. When dry the frames are removed from the plans. Trim the trailing edges and tips to a streamline shape, using a razor and sandpaper for this work. Check the rudder and stabilizer for warps. If you can, remove with steam. If it is necessary to use wood other than balsa for the stabilizer and rudder, it must be remembered that they be light but still strong. To accomplish this reduce the size of the various parts.

WING: The wing is easiest assembled in one piece; the builder will have to make a left side plan as there was insufficient room for it on the drawing. Ribs are cut from 1/16 sheet balsa and two of each is needed except No. 1. Sand them. carefully to the exact size and cut notches for the spar. Spar is cut from 1/16 sheet balsa as shown by the dotted lines. Leading edge is 1/8 x 1/4, trailing edge is 1/8 x 3/8 tapered stock. Tips are cut from 1/8 sheet and assembled over the plans. With pins hold the various parts in place over the plan until the cement has set. When dry, crack the spar and edges and install the required dihedral; recement the dihedral joints firmly. Finally trim and sand the leading and trailing edges and tips to conform with the airfoil shape.

To keep weight down to a minimum the builder using heavier wood will have to use material of smaller crossection, particularly the leading and trailing edges. Ribs should be cut from the thinnest stock and lightening holes at points of little stress will tend to reduce the weight of heavier material.

A landing gear of the type used on the Valiant always presents a problem to the model maker. However, the landing gear developed for this model is easy to make, accurate in appearance and strong enough to take all the abuse the model can give. .040 steel wire is used and the top is bent in such a manner as to join the wing spar and rib No. 3. Make a right and left strut. With thread bind the struts to the spar and then use needle and sew right through rib No. 3, and about the wire. Apply several coats of cement to the thread wrappings and adjacent areas. The rubber tubing covers are not slipped on until the wing has been covered..."

Note this plan has been stitched together from raw scans posted at http://www.theplanpage.com/Months/2108/2108.htm

Direct submission to Outerzone.

Supplementary file notes

Article, thanks to GTHunter.

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