Pinch Hitter (oz1090)

 

Pinch Hitter (oz1090) by Paul Plecan 1943 - plan thumbnail

About this Plan

Pinch Hitter. Free flight gas model. Designed to be built using pine/spruce, during WWII when balsa was not available. Note this is not a full-size plan.

Quote: "Pinch Hitter, by Paul Pleacn and Gil Shurman. No balsa? Don't worry! Learn all the secrets of hardwood technique by building this 'substitute' gas job.

HERE y'are, boys - a gas job, complete, ready to fly, without even a splinter of balsa in it. Here are some of the advantages: First, it's cheaper, as you can always pickup some scrap pine or spruce and have a friend strip it for you. Second, the all hardwood construction makes possible a tough and resilient framework that can 'take it' better than any balsa model. The design lends itself to contest work very well - what with its thin flying surfaces, general sliminess, high-lift airfoil, generous moment aria, and reflex section stabilizer airfoil. If you have a Rogers 29 or similar motor on hand, try building this unusual ship.

The original model gave the authors quite a shock in that it didn't quite reach weight rule, necessitating additional doping and heavier batteries. The most outstanding characteristic, however, is the flexibility of the model. Subjected to plenty of flying and transportation manhandling, the model is still in perfect condition. Impacts have shattered the tissue at times, but the framework is still as sound as the day it was assembled.

You, too, can make the Pinch Hitter. It's easy. First, two main side frames are constructed of 1/8 square pine, spruce, or what have you. Even mahogany is OK, but don't saw the legs off the family piano! Almost any type of glue can be used, as parts of the original model were held together with Weldwood, Casco, and regular cement. No difference in strength has been noticed, but it should be mentioned that three coats of cement were used where formerly one sufficed.

Allow the main frames to dry by working on some other part to take up your time. The cross pieces are now cut out according to the lengths given in the top view. The two sides should be assembled directly over the top view before adding stringers. See sketch on plan for details of braces that run through fuselage to support the stringers. Odd lengths can be used here, as they will be trimmed to exact size before the stringers are added. These braces should be fastened to the cross braces and uprights with a few turns of thread and at least two coats of cement to secure them in place. Since the rudder is so simple, it may be assembled right on the fuselage once the curved sheet pieces have been cut out and the outline cemented together. All that remains is to fit the spar in place and bend the cap-strip ribs around it. Do not forget to taper the last inch of the spar tip so that it blends into the thin curved-sheet outline above it. Wing-mount formers W-1 are now cemented in place, care being exercised that they remain flat while the cement dries, providing a smooth area for the wing to rest on.

The stabilizer is constructed next. Pin down the outlines directly on the plan and place the bottom rib cap strips in their respective positions. The spar is tapered now and fitted in place, followed by bending the top rib cap strips over it to obtain the desired camber. Cut the bottom portion of the rudder to outline shape and cement to the cambered side of the stabilizer.

The wing ribs are cut out of 1/16 sheet pine en masse, once a motordriven jig saw has been located. Maybe one of your friends has a vibratortype saw, which will be highly satisfactory. Cut eighteen sheets of wood to the necessary width and length, and after they have been lightly nailed together, trace the main rib outline on the top one. Now you can go to town with the saw, but be careful, as an airfoil with smoothly blended curves is the only type that is efficient.

Cut the trailing edge short on two of these ribs to obtain the # 11 ribs. The tip ribs (#12) are now cut out, followed by cutting out the centersection ribs (three required) which are split vertically to allow space for the spar joiners. Assemble both panels on a flat surface and allow to dry well. After propping up the tips 6-1/4 in, the spar joiners may be added (see sketch on plan). After the cement or glue has dried, cover the center-section leading edge with two-ply bristol board or similar material to strengthen the center portion..."

Supplementary file notes

Planfile includes article.
The same scan of the same plan, now scaled up to fullsize at 56in span. It is low resolution, but usable.

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Pinch Hitter (oz1090) by Paul Plecan 1943 - model pic

Datafile:

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Pinch Hitter (oz1090) by Paul Plecan 1943 - pic 004.jpg
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Notes

* Credit field

The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.

Scaling

This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.

 

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