Researcher 7 (oz8054)

About this Plan

Researcher 7. Radio control sport model. Twin-boom design.

Quote: "The Researcher No, 7 design is the direct result of two years of intensive study, testing and building the six 'Researchers' that preceded it. Each one of the ships, No. 1 through No. 6, all contributed to the configuration, structural design, and equipment placement in ship No. 7.

Ships No. 1 and No, 2 had a 70 inch wingspan and angled booms that positioned the stabilizer above the thrust line, Both had a semi-symmetrical airfoil. These two features caused the planes to climb at higher airspeeds with a nominal roll rate. Both planes weighed in excess of ten pounds. Ship No. 2 utilized rudders but they were ineffective

Ship No. 3 approximated ship No. 7's configuration but utilized a semi-symmetrical airfoil with a 48 inch span and 38 inch length. The booms and horizontal stab were centertined as was the thrust line. Its airspeed capabilities were far better than ships No, 1 and 2. The roll rate, pitch rate, and rate of vertical climb were almost double that of the previous planes, while the slow flight capabilities were almost unbelievably slow without any tendency to inadvertently snap.

Ship No. 4 was a departure from the previous three in order to examine the possibilities of even a shorter wingspan. No. 4 was a flying wing type with a 36 inch span, 24 inch chord length and a 4 inch chord depth. It was a pusher, like the rest, but had a symmetrical airfoil and no booms. The prop ran in an opening in the wing with the stab in line behind the propeller. This plane had absolute stability with a slow roll and pitch rate. It flew as well inverted as it did right side up. Large fins at the ends of the wing gave good directional stability, but due to the slow roll and pitch rate, ship No. 5 became necessary.

Ship No. 5, I decided, would have all the features I thought necessary for a truly high performance WC airplane. A symmetrical 36 inch span, 14 inch chord length and 2 inch chord depth wing was used with a 36 inch O.A.L. Flaps opposite the elevator and the rudder with large upper and lower centerline fins were employed in an attempt to increase the pitch and yaw rates. A short in my transmitter antenna lead ended this test on the first flight, too soon to evaluate the merits of the above mentioned features.

Ship No. 6 was almost a duplicate of No. 3 with the following excep-tions: a thick symmetrical airfoil and large rudders were used with an attempt made at making the booms lighter and the nose wider. The roll and pitch rate of this plane was rather slow and the rudders were ineffective, causing only a little adverse yaw. This plane, like all of the "Researchers", had wide main gear, nose wheel steer-ing and brakes which made ground handling a pleasure. Armed with the previously mentioned performance characteristics and functional advan-tages which will be brought out later in this article, Researcher No. 7 was built and test flown in the following sequence:

Construction. A 12 x 48 in piece of plywood, 1/2 in thick, covered with a 1/2 in thick piece of Celotex makes an ideal portable jig and building board for this plane. In this manner, you can work on the coffee table, kitchen table, or card table, and pick it up and put it away while the plane is in the con-truction stage if necessary. Construction proceeds as follows:

Cover the workboard with Saran Wrap, install six 3 in pieces of masking tape across the two 1/4 x 1/2 boom webs in equal distances from one end to the other, and pin the webs to the workboard, making sure they are pinned straight with the sticky side of the tape facing up.

Lay the arrowshafts down on the tape, touching the web full length. Roll the arrowshafts away from the web 90 degrees and run a heavy bead of epoxy cement along the full length of the tops of the arrowshafts, Then, roll one arrowshaft in next to the web and press the tape down against the top of the web. Roll the other arrow-shaft in against the other side of the web and press the tape down on top of the first tape strap. Once again, sight down the broom assembly and make sure it is perfectly straight. If a bow is left in them at this point the bow will be permanent when tilt epoxy sets up. Centerline one of the wing ribs on one end of both booms and mark and cut the end of the booms to coincide with the nose of the rib. This will insure a snug fit in the leading edge and give proper wing-boom alignment when the booms are installed. Cut the aft ends of booms to the correct length and you have just completed a major portion of the model's construction.."

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