MICRO-FLYING
3D RESIN-
PRINTED
MICRO
AIRPLANES
By Joe Malinchak | joemal@echoes.net
MY FRIEND, Gordon Johnson, has been exploring the use of 3D resin-printed parts on micro airplanes. His latest is a Stick Bombshell, which has Bombshell-shaped wing and tail surfaces with a carbon-fiber stick fuselage. It’s covered with transparent iron-on covering to show off the built-up balsa flying surfaces. Gordon describes it as an Old-Timer-looking stick airplane that is similar to a Vapor but with a slightly larger wingspan at 18 inches.
The goal for the airplane was to have a similar or lower wing loading than that of the current Night Vapor, which, at 25 grams, has a loading of 1.7 ounces per sq. ft. The Stick Bombshell has 110 sq. in. of wing area and came in with a final weight of 27.7 grams and a loading of 1.3 ounces per sq. ft.
The Stick Bombshell is powered by a brushless gearbox made by a hobbyist named Vladimir in Russia (Vladimir88 on RCGroups) that weighs a mere 1.77 grams and puts out 23 grams of thrust from a 5-inch propeller.
Gordon’s other goal was to see whether he could design and print all of the pieces to connect the carbon fiber and balsa on his Elegoo Mars 4 3D resin printer. He designed the pieces using Fusion 360, which has a free version for hobbyists. Printed pieces include the motor mount, battery mount, receiver mount, landing gear, wing pylon connecting pieces, the mount for the horizontal stabilizer, and even the mount for the tail skid. Gordon also designed and printed micro versions of five-spoke star wheels that are popular for park flyers and made black foam tires for them.
A picture is worth a thousand words, so look at those in this column for close-ups of some of the printed pieces in this airplane. Gordon also has a
build thread on RCGroups in the Scratchbuilt Indoor and Micro Models forum, with lots of details on this model.
Gordon’s other goal was to design and 3D-print the servos to control the airplane. These servos were a collaboration with Dan Schlarch, from Georgia. Contact Dan at the email address located at the end of this column in “Sources” for more information about these servos.
The servos weigh 0.75 grams each, and the gears and housing were resin-printed.
The processor is from a Buzzard Models 1.7-gram servo that uses a magnet and Hall sensor for positioning feedback.
The design goal of this airplane was for it to be able to cruise around at an indoor flying facility similar to a Vapor but to be different and look like an Old-Timer. The first flight of the Stick Bombshell is on Gordon’s YouTube channel; the link is listed in “Sources.” He said that it required almost no trim and flew nicely right away.
This model demonstrates that hobbyists can now design and print a multitude of plastic pieces with incredible precision by using 3D resin printers. Until recently, these kinds of fittings and pieces had to be manufactured in large quantities using injection-molding equipment and expensive molds. 3D resin printers allow pieces to be designed for one-off micro models. Care needs to be taken to balance strength with weight; however, Gordon’s model shows what can be done by a hobbyist with a fairly standard 3D resin printer.
SOURCES:
Stick Bombshell 1st Flight
YouTube
https://youtu.be/nXHkgTTwigA?si=Gqo8s9_P1nETyYK
Stick Fuselage old timer Baby Bombshell (now w/Video)
RCGroups
www.rcgroups.com/forums/showthread.php?4604111-Stick-Fuselage-old-timer-...(now-w-Video)
Dan Schlarach
danlovesbetsy@gmail.com
Buzzard Models
info@buzzardmodels.com
www.buzzardmodels.com
Elegoo
3dp@elegoo.com
https://us.elegoo.com
Autodesk
www.autodesk.com
