Blippy (oz2514)

About this Plan

Blippy. Kochman's Blippy from American Modeler November 1957. A 40 inch span single channel RC with tricycle gear.

Quote: "In our last issue Aubrey Kochman told you how to check out your first radio control plane; now try his simple, sturdy wee rudder-only job. Blippy, by Aubrey Kochman.

Blippy was designed as a 'second' model to be small, compact and easily transportable even when the entire family - dog included - took off for a weekend jaunt to an R/C session. The choice of taking a five or six foot model and leaving part of the family at home or a 40 inch job and maintaining the peace made the smaller model a must.

Having a rather beat-up but still stuntable Babcock 465 mc two-channel job in flying condition, we planned this more realistic model for sport flying. Blippy has worked out so well it's now first in the hearts of the entire family.

As noted on the plans, fuselage width is governed by the size of the BCR-8B receiver box. Incidentally, this method of mounting has proven highly success-ful in preventing receiver damage under the most severe conditions. This radio compartment should be adequate for any rudder-only equipment and still leave plenty of hand-room for adjust-ment purposes.

Our finished model tips the scales at 30 ounces. Even so she is capable of some pretty fancy loops and rolls. With careful choice of lumber and a few less coats of color dope you can easily trim off 5 or 6 ounces which should result in a fully stuntable little bomb when powered by a hot .049 diesel or a docile .074 glo. For you sharp eyed readers, the .065 shown in the photos and used on the initial test flights has since been re-placed with an .074 Cub. A half plugged venturi and 3 degrees downthrust keep Blippy from reaching for too much alti-tude with glow. (An .074 diesel is cur-rently powering the model.)

As with all radio jobs, it is best if all necessary radio gear is on hand before construction of the fuselage begins. In this way should you not use the same receiver or escapement as the plans indicate it is simple to make the necessary construction changes for proper installa-tion of your equipment.

Construction-wise Blippy is quite conventional. Select two sheets of 3/32 by 3 in medium hard balsa preferably quarter grain stock for fuselage sides. It is important that the top edge of these sheets be absolutely straight as all incidence angles are measured from it.

In order for the bottom keel piece to fit properly the following procedure is recommended: cut one of the side pieces to shape as accurately and smoothly as possible; sight along the cut edge and use a sandpaper block to smooth out any irregularities; use this side as a template for the other side; cut very carefully so that no sandpapering is required. If done accurately this single cut has shaped the bottom edge of the side and the top edge of the bottom keel piece. Now cut the bottom edge of the keel to shape and set it aside.

Cut the slot for the stabilizer 1/4 in down from the straight edge of each side piece and parallel with it. Cabin side pieces between F1 and F3 are cut to shape and cemented in place. These should be 1/4 in higher at F2 than at F3. Mark off the position of all formers and the vertical 1/8 x 1/4 braces on both side pieces - cement in place. The diag-onal braces in the cabin section may also be added at this time or after F2 and F3 are in place. Cut all the formers to shape and cement F1, F2 and F3 in place. Check for squareness then add F4, F5 and F6.

Now install the escapement mount and torque rod. If other than a Babcock 465mc receiver is to be used decide on the type mounting and make the necessary provisions.

Add the 1/8 x 1/4 backbone piece between F3 and F6. Cut both formers F7 to identical shape and cement in place against F3 and the backbone. Sand the backbone to conform to the taper of the formers; start planking at F6 and work forward. It is best to plank both sides at the same time to prevent distortion. When you reach F4 install the Babcock 'J' antenna mount under the backbone between F3 and F4. Solder the vertical antenna in place. Complete the planking.

Bend main landing gear to shape; use J bolts to mount it to 3/32 plywood. Double cement the mount in place; when dry apply a third coat of cement.

Mark exact center on the bottom of all formers; cement bottom keel piece in place. Cut out for nose wheel clearance; add triangular bottom formers. Use soft 1/16 sheet to plank the bottom - note grain direction. Cut planking to form nose wheel well, use scrap balsa to fill in around the well. This is important to prevent dirt, grass and pebbles from getting into the fuselage through an otherwise open hole.

Nose gear is formed and mounted to F1; it is 1/8 in longer than the main gear. This reduces the distance of the take-off run and also allows the nose wheel to take the brunt of hard landings.

Cement 1/2 in sheet balsa to F1 to form the nose block; carve to shape. If a beam mounted engine is to be used, cement hardwood bearers in place. An additional sheet of hard 1/8 balsa may be used to space bearers properly. If a radial mount is required add a second 3/32 plywood firewall, positioning it for sufficient propeller clearance. Do not shorten the nose.

There is ample space in the battery compartment for additional A and B batteries if required. If such are needed eliminate the 1/8 sheet battery box... "

Update 04/02/2019: Added article, thank to RFJ.

Supplementary file notes

Article.

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