ST4 OWL Flying Videos and Pictures

This model is inspired from the Stick Style model. Compared to other ST models, this AUW model has less weight due to its fuselage size. The wings consist of two parts (left wing and right wing) making it easy to transport. The wing control surfaces are ailerons and also flaps.  ST4 would be an all around model that you always want to bring with you to the flying field. With WCL around 10 – 11, it is not only good flying it as a sport flying plane but also doing some aerobatic maneuver.


Try to avoid printing all parts with 0.40mm extrusion width for getting the best experience with the model. If you still want to print with that extrusion width then try to print some parts with LW-PLA, ePLA-LW or PolyLight 1.0 such as stabilizers (at least/recommended). Saving some weight on the stabilizer parts will save significant amount of weight for the battery (nose side) to get the correct CoG.

ST4 OWL videos posted on the youtube were printed with all PLA+ and 0.32mm extrusion width. 

Spar Requirement:


– Primary Wing Spar : 1 x 12mm OD and 1000mm long fiber carbon tube (Required).

– Secondary Wing Spar : 1 x 8mm OD and 300mm long fiber carbon tube (Optional).

– Horizontal Stabilizer Spar : 1 x 5mm OD and 450 long fiber carbon tube (Optional).

Fiber Carbon/Aluminum Landing Gear Installation (Optional):

– Main landing gear base is provided if you would like to install your own landing gear.

– With the base glued into the fuselage (suggested to use hot glue), you can use screws to attach the landing gear.

– STL and STEP files are provided under “ST4 OWL – SUPPORT” Directory.

Center of Gravity (CoG):

FUSELAGE-0 Long Nose to Make CoG Correction

Weight and Time Estimation:

Following tables show the weight of printed parts, number of required filament rolls and time required to print. The numbers are taken from S3D slicer calculation. From experience, actual numbers show about -5% less than depicted in the table. But the number may vary from printer to printer due to:

– Stepper Jerk value.

– Stepper Acceleration value.

– Steps per unit (either calibrated or uncalibrated)

– Extruder quality/condition.

– Nozzle quality/condition.

– Filament quality/condition.

– Etc. 

For sure the relative number are useful when deciding to accept the total strengths or weights when printing. Picking higher strength to some parts are necessary to avoid breaking during high impact landing or sharp maneuver for example.  

Here are the summary tables:

Table of Contents

Update History

No Update for this model yet.

Recommended Setup

Battery Protector and/or Weight Balancer Holder for 2200mAh 3s/4s and 3300mAh 4s Battery:

One of challenges in 3D printed plane is where it has a wide range of possible total weight result. For example, the plane printed with 0.40mm comparing to 0.32mm extrusion width may end up the CoG moved about 2cm – 3cm backward with using the same battery. You may need to move the battery forward or add more weight at the nose to get back the CoG to its previous location. To solve this issue at the same time protecting your battery, the following STL files are created for your 2200mAh 3s/4s and 3300mAh 4s. Feel free to download and use the files (G-code files are also provided for Bowden or Direct Drive setup including STEP files).

Tools and Materials

OWLplane Printers (for your ref.)

See figures below some printers used, created, developed and modified by OWLplane. Two group printers are set, the first one is utilized only for printing PLA/PLA+ and the other one is utilized to print with ABS, ASA and HIPS filaments (the one with enclosures). Just hover onto the figures to find more information about them.

Modified all Bowden setup printers into Direct Drive but leave Tevo Tornado and Anycubic Mega as is (still in bowden setup).

Hardware Needed

For Fuselage and Hatch :

For Wings (except the control surfaces):

For Aileron, Flap, Stabilizer, Rudder and Elevator Servos:

*) Illustration only

Setup for Servo Travel/Throw

Suggested setup for medium travel/thrown are depicted below and you may adjust the setup according to your need.

3D Printed Motor Mount, Propeller Spinner, Collet and Spar

Motor Mount Requirement

Motor mount wall should be 3D printed with more heat resistance filaments such as ABS, ASA or HIPS. If your 3D printer does not have enclosure you may want to try with PETG filament (more heat resistance than PLA/PLA+). In case you still would like to use PLA, please do annealing process (not sure can do for standard PLA), some successful with HT-PLA/Hight Temp-PLA. Click here for you to read about annealing article.

Motor Mount
Propeller Spinner and Collet Requirement

OWLplane does not provide STL file for printed propeller spinner due to our concern about strength, shape and uniform weight when spinning at high speed. Not all 3D Printer has really free of skew issues for all their axes. The skew issue generates uneven shape that will lead to problem when spinning. Good spinner should be available in your local hobby store or online store, even that spinner, you still need to balance it before using it.

Spinner and Collet Requirement :

1. 50mm Diameter Size Spinner.

2. 5mm or 4mm Shaft Propeller Collet (check your purchased motor shaft to pick the right size propeller collet).

Please watch the following Videos to balance your Propeller and Spinner:

Assembly Figures

ST4 Fuselage Assembly

ST4 Wing Assembly

ST4 Horizontal Stabilizer Assembly

ST4 Vertical Stabilizer Assembly

ST4 Hatch Assembly Animation

ST4 Main Gear Assembly

Watch ST4 OWL Animation and Assembly Video
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