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RC Jets: Parts and Construction

From "Radio Control Hobbies"
episode RCH-210

Bob Violett shows Chris a sheet of laser-cut parts used in the construction of BVM jets.

In this segment, Bob Violett takes Chris Chianelli on a tour of the BVM facility where the parts are manufactured and elements are assembled for high-end RC jet aircraft.

Because RC jets travel at such extraordinarily high speeds, structural integrity of the airplane bodies is essential. The parts that make up those airplanes are precision-made at BVM. Thousands of individual parts are cut by lasers that are controlled to exact specifications by computer.

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Figure A

Figure B

High-End Manufacture of High-Performance Parts

A sampling of the precision-made parts can be seen on a sheet of plywood that has been laser-cut into a number of individual parts for BVM's Bobcat ® model (figure A). This sheet includes ribs and other parts for assembly. The parts are all made from a computer-based template so that they fit together simply and securely. One of BVM's aircraft might typically contain around 100 of these kinds of components.
The same computer-controlled technology is used to cut out parts using a router that turns a carbide cutter-bit at 25,000 rpm (figure B). This machine is used to cut carbon-fiber parts as well as some critical plywood parts.

Figure C

Figure D
The technology being used is known as CNC manufacturing, with the initials standing for "computer-numeric control." As an example, for wooden frame-parts, the computer directs a CO2-laser as it cuts precise and intricate designs from 1/8-inch plywood (figures C and D).

Figure E

Figure F

Parts Assembly

Bob next takes Chris to a part of the BVM facility where individual parts are put together to form individual elements for the jet-craft such as wings and fuselage.

Technician Dave Valdez specializes in the assembly of the F-100 wing (figures E and F), among others. He has been building BVM jets for 14 years. Here Dave is putting on the final application of glue in the assembly of the internal structure of the wing.

Figure G

Figure H
The skin of the wing, made from a laminate of fiberglass cloth, balsa-wood and carbon-fiber, is first laid into a female mold. The skin is then sealed in a vacuum bag and placed in an oven and cured overnight. Once it is removed, it is sanded and prepped for then internal elements to be put in place.
Carbon-fiber and balsa-wood structural elements, made earlier on the CNC machines, are meticulously laid in place, connected and glued using a specialized "aeropoxy" glue (figures G and H).
Once the internal parts are all in place, the top skin of the wing is put in position and the entire wing structure is clamped securely into a mold to allow it to cure. The result is a single, structurally rigid wing-piece.
The wing has fiber spars that are bolted together and that interface with the fuselage and landing gear of the plane. The F-100 has a leading-edge slat that moves during takeoff and landing, so slat-tracks must be built into the wing using a very accurate fixture. Precision-made slat rails, the separate slat piece and the servos for the ailerons and landing gear are hand-installed by the modeler in final assembly of the plane's wing.

Figure I

Figure J

Figure K
The jet fuselage is created using a mold. Fuselages are left in the mold until they are ready for use. The top portion of the mold is removed to reveal the structure of the fuselage (figures I and J), including a considerable amount of detail that comes from the mold template-pattern.
The mold-pattern is made using the CNC technology and, in this case, includes gun-ports, vents, landing-gear doors speed-break recesses, and panel lines.
Meticulous care is also used in making the supporting framework used to create the canopy section of the jets (figure K). The wood framework structure keeps the part stable, making it easier for the modeler to work with. The internal framework parts are made using the CNC laser machine and essentially serve as a jig during the manufacturing process. Once the canopy is complete, the internal wood parts can be removed.