PT-17 Stearman

PT-17 Stearman side
Stearman top
Stearman partsUsing PETG to print the PT-17 Stearman

My third printed RC plane is this Stearman. I tested single layer printing on my printer in PETG for this aircraft. Information about my 3D printing equipment you find in the post; printing the Kodo.  You can buy the STLs and Simplify 3D factory files from 3DLabPrint. I used Makerfill PETG for wings and fuselage, Polylite ASA for the black landing gear components, and some other smaller parts. PETG print filament is similar to PET (Polyethylene Terephthalate) but with enhanced properties due to the addition of glycol (PET+G = PETG or polyethylene terephthalate glycol-modified). Due to the excellent strength and impact resistance, PETG is appropriate for stress withstanding applications. Being amorphous in nature, PETG has good flexibility, machinability, and thermoforming characteristics, which allows the material to be hotline bent and welded. Here are some of its 3D print advantages; excellent layer adhesion, warp resistance, reduced shrinkage, high water-resistant, high temperature resistant. The temperature tolerance for PETG is around 75ºC. With PLA, on the other hand, you generally have to keep 3D printed parts below 55ºC to keep them solid. The cons of PETG for RC planes are higher flexibility can lead to twisting of the wings or fuselage during flight and the rather high density leading to a higher wing loading. To get good adhesion between the layers for single layer printing I had to give more filament material by setting the extrusion multiplayer 1.03 for the 0.25 mm layer height. Printing PETG material has some cons; PETG has a high density of 1.27 g/cc, so the plane will be havier than printed in ASA, HIPS, and lightweight PLA. There is also a tendency to have a lot of stringing and it's difficult to make bridges. To solve these problems and keeping printing time reasonable I had to print each part in more than one process. So I could change the print settings for some heights areas. For example for bridging, I had to slow down and reduce the extruder temperature on specific height areas.  Also, to reduce the stringing I try tried to use a filament retraction distance as low as possible on my printer, and use some coasting- and wipe distances.  To make some parts stiffer I had to print some heights areas of a part in a double-layer wall. My printer setting for PETG: Printing volume 200x200x180 mm, Extruder 0.4 mm, Layer Height 0.25 mm, Extruder Temp 245-235 ºC, Filament Speed max 40 - 15 mm/s, Bed 80 ºC, Cooling 60%-100%.

Electronics for this PT-17 Stearman

I used an Extron motor 2826/10 KV860 Outrunner with an Extron iQ-40 ESC, 4 Savox SH-0255 MG (Metal gear) servos, a Spektrum AR6610T 6 channel receiver,  and a Gens ACE 3000 mAh.


MOD1: Modified print processes to be able to make PETG bridges, avoid stringing, and to reinforce some part by printing some 2 layer bands.
MOD2: Modified motor section with extra an extra 20 mm motor shim, drilled holes in the 7 cylinders, and added approximately 70-gram lead to adjust the Centre of gravity.
MOD3: Modified the landing gear with metal springs and inox wheel shafts and copper tubes, and printed a higher infill in the front part of the PETG landing gear legs to get these stronger.
MOD4: Added A3Pro Gyro from Hobbyeagle to improve stability and the use of failsafe modes.
MOD5: To improve the looks I printed the plane in blue and red transparent PETG, the windscreens completely Makerfill transparent PETG, and the pilot chairs in Polymaker Polywood.
MOD6: Printed the tires in Makerfill Flex with no infill.
MOD7: The stripes on the ailerons, elevator, and rudder as are small pieces of red Oracover Transparent Fluorescent film ironed on the PETG.


Till now I did not maiden this RC Airplane. Al static tests were OK, the plane was certified for flying at or our RC terrain in Lier, Belgium, and I did a photoshoot. When the weather improves I will fly this plane.

Aircraft Characteristics after Modifications

Wing Span: Bi 1.2 m
Length: 0.9 m
Flight Weight: 2.7 kg
Wing Aera: 45 dm2
Wing Loading: 60 gr/dm2
Wing Cube Loading: WCL 8.9
Power: 4S 3000 mAh
Motor: Extron 2826/10 KV 860 Outrunner
Propeller: XOAR 1x 12x6 2-blade
Stall Speed: 34 km/u
Sound Pressure: 50 dB(A)/7m



Kodo Glider

Kodo side
Kodo wing
Kodo fuseStarting 3D printing RC Airplanes

This glider was my first attempt to print an RC airplane. Beginning 2019 I started to explore 3D printing. My first printer was a Da Vinci Jr 1.0 Pro from XYZprinting. The advantage of this printer is you didn't have to use only the filament from the printer manufacturer. The cons are small and not heated bed with limited slicer software. So I could experiment with PLA filament of different manufacturers and use other slicers like Cura. Finally, now I use the Simplify3D slicer, and mostly Polymaker and Makerfill filament. I try to keep the filament dry in some Polybox containers from Polymaker, use an Esun eBox Filament Dryer as a feeder. In September 2019 I bought a Balco Touchscreen 3D printer. This printer originated from a Wanhao Duplicator I3 plus. I did a lot of printer modifications, like a Plexi enclosure with some rpm-controlled fans, a glass plate on the bed, a Microswiss All metal Hotend with a Slotted cooling block, and a CNC Machined Lever and Extruder Plate. I Have upgraded the Balco firmware to ADVi3++ and use a Raspberry PI with Octoprint software and the Printoid App on my Android phone.  To connect to my printer from anywhere I have a separate Raspberry PI gateway with OpenVPN.

Printing the Kodo

When looking on the Internet for 3D printed RC airplanes I was charmed with the design of the Kraga Kodo. Here you can read the story behind Kraga. The combination of carbon struts, covering film, lightweight design, the compact fuselage with carbon reinforcement, and carbon tail tube.  Because of the rather low deformation temperature of PLA (55 ºC) and limited UV resistance I choose the white and black Polymaker Polylight ASA filament and Oracover Red Transparant Fluorescent film. ASA is light UV improved ABS with higher temperature (75 ºC) resistance before deformation than PLA. Polylight ASA has a lower specific weight of 1.04 g/cc versus 1.27 g/cc for PLA. I designed some extra ASA parts in FreeCAD 0.18  as battery support, a receiver-, and gyro support, some new tail horns, and winglets. Some of my Printer settings are; minimum Printing volume 200x200x180 mm, Extruder 0.4 mm, Layer Height 0.19 mm, Extruder Temp 245 ºC, Filament Speed max 40 mm/s, Bed 90 ºC, Cooling 0%.

Electronics for this Kodo

I used a Pichler Boost 18 motor with KV 1050 with a Pichler Boost  XQ 30 ESC, 4 Savox SH-0257 MG  (Metal gear) servos, a Spektrum AR6610T 6 channel receiver,  and a Turnigy nano-tech 3S 950 mAh battery.


MOD1: Modified the main wing connection with printed and glue base plate on the main wings and two super magnets.
MOD2: Modified the carbon control rods and newly designed ASA tail horns for the control surfaces of the V-tail to make steering directer and without play and binding.
MOD3: Added winglets to the main wings to try to improve the stability of the main wing and reduce the twisting forces when taking fast turns.
MOD4: Added A3super 3 Gyro from Hobbyeagle to improve stability and still to be able to use the ailerons as spoilerons to reduce landing distance.


A successful maiden flight. Good protection connection of the main wing, because I had a not so perfect grass landing, and on one wing part separated without any damage! There were some remarks from spectators about the flexibility of the main wing. They believed that the main wing would not hold, but it still does. A good gliding angle. I had to use the spoilerons to slow down the glider in the final landing phase to make it easier to land on the grass runway. After more flights and more wind, I experienced probably twisting of the main wing and in a low fast turn and had a crash, probable because of the twisting and some play on the V_tail steering.  I had only to replace the tail carbon rod and glue some cracks in the fuselage and one of the wings. Impressive little damage after flying into the ground. I modified the steering for the V-tail and installed the HobbyEagle A3super 3 V2 programmable 6-axis gyro. Did some more test flying. This plane performs well but the rather large flexibility of the main wing in ASA remains a weakness, probably because of the different material properties between ASA and original by Kraga proposed PLA.

Wing Span: 1.8 m
Length: 0.9 m
Flight Weight: 0.8 kg
Wing Aera: 26 dm2
Wing Loading: 31 gr/dm2
Wing Cube Loading: WCL 6
Power: 3S 950 mAh
Motor: Pichler boost 18 KV 1050 Outrunner
Propeller: 1x 9x6  2-blade folding
Stall Speed: 20 km/u
Sound Pressure: <50 dB(A)/7m