Trying to make a 3D printed version of the FT-Versa wing similar to Hotwire foam cut variations

[TheDaringPilot]

I am trying to find an airfoil to match the Versa Wing but failed to find a good replacement or match. The closest was the Clark Y, but when asking AI if that airfoil would work I got mixed responses. The reason I’m doing this is because I crashed my Versa wing last year at FF and it made me think of trying a different material to make the airplane. I thought of 3D printing because I have a Lulzbot Taz WH and the filament that the printer supports ranges from PLA; to abrasive and extremely durable heat resistant materials.
I already started by using the dimensions from the airfoil of the Versa wing that I crashed. I used AutoCAD to take the PDF of the Versa wing plans and convert it into a sketch that Fusion 360 can read. I didn’t succeed with remodeling the airfoil because the Versa wing doesn’t come with a side view of the airfoil in the plans. The one that I crashed was too badly damaged to get accurate measurements.

What I need help with finding is:

What airfoil works with the FT Versa wing?
I found out the MH-45 is a common flying wing airfoil but because the Versa wing has a flat bottom I don’t know if that would work?

What other airfoils does the hot wire foam cut Versa wing models use?

What would you recommend the washout and reflex be when using that airfoil?

Anything else that is important?

My goals for the project:

1. Keep it simple
2. Use the original plans of the Versa wing (especially keep the control surfaces or elevons the same)
3. Easy to 3D print and assemble
4. Have it done before FF (yes I know it’s 39 days away and counting)

 

[TheDaringPilot]

I did some more research and found a website that answers most of my questions. https://www.mh-aerotools.de/airfoils/flywing1.htm
It looks like an airfoil with reflex is the way to go. I read a research paper that stated the Clark YH airfoil is often used in flying wings. https://www.afahc.ro/ro/revista/2021_1/4-VasilePrisacariu.pdf

I think I’ll use the Clark YH airfoil with reflex. I just need to find the correct washout.
Any ideas?

 

[TheDaringPilot]

I got impatient and was worried about running out of time for this project so I used AI to help find the correct washout for my wing.
Grok AI is amazing!

Provided Data​

• Wingspan: 965 mm (0.965 m)
• Root chord length: 342.924 mm (0.342924 m)
• Tip chord length: 158.756 mm (0.158756 m)
• Leading edge sweep: 31.3 degrees
• Airfoil: Clark YH
• Airfoil thickness: 100% at root, 60% at tip (implies a scaling of the airfoil thickness from root to tip)
• Source: Airfoil data from airfoiltools.com

Analysis​

1. Wing Geometry:
   • The wing is a tapered, swept flying wing with a taper ratio of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mfrac><mtext>tip chord</mtext><mtext>root chord</mtext></mfrac><mo>=</mo><mfrac><mn>158.756</mn><mn>342.924</mn></mfrac><mo>≈</mo><mn>0.463</mn></mrow><annotation encoding="application/x-tex"> \frac{\text{tip chord}}{\text{root chord}} = \frac{158.756}{342.924} \approx 0.463 </annotation></semantics></math>root chordtip chord=342.924158.756≈0.463.
   • Wingspan of 965 mm gives a semi-span of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mfrac><mn>965</mn><mn>2</mn></mfrac><mo>=</mo><mn>482.5</mn><mtext> </mtext><mtext>mm</mtext></mrow><annotation encoding="application/x-tex"> \frac{965}{2} = 482.5 \, \text{mm} </annotation></semantics></math>2965=482.5mm.
   • The leading edge sweep is 31.3 degrees, indicating a moderately swept delta-like or trapezoidal planform.
   • The mean aerodynamic chord (MAC) can be approximated for a tapered wing as: <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mtext>MAC</mtext><mo>=</mo><mfrac><mn>2</mn><mn>3</mn></mfrac><mo>⋅</mo><mtext>root chord</mtext><mo>⋅</mo><mfrac><mrow><mn>1</mn><mo>+</mo><mi>λ</mi><mo>+</mo><msup><mi>λ</mi><mn>2</mn></msup></mrow><mrow><mn>1</mn><mo>+</mo><mi>λ</mi></mrow></mfrac></mrow><annotation encoding="application/x-tex">\text{MAC} = \frac{2}{3} \cdot \text{root chord} \cdot \frac{1 + \lambda + \lambda^2}{1 + \lambda}</annotation></semantics></math>MAC=32⋅root chord⋅1+λ1+λ+λ2 where <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>λ</mi><mo>=</mo><mn>0.463</mn></mrow><annotation encoding="application/x-tex"> \lambda = 0.463 </annotation></semantics></math>λ=0.463. Plugging in: <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mtext>MAC</mtext><mo>=</mo><mfrac><mn>2</mn><mn>3</mn></mfrac><mo>⋅</mo><mn>342.924</mn><mo>⋅</mo><mfrac><mrow><mn>1</mn><mo>+</mo><mn>0.463</mn><mo>+</mo><mn>0.46</mn><msup><mn>3</mn><mn>2</mn></msup></mrow><mrow><mn>1</mn><mo>+</mo><mn>0.463</mn></mrow></mfrac><mo>≈</mo><mn>251.6</mn><mtext> </mtext><mtext>mm</mtext></mrow><annotation encoding="application/x-tex">\text{MAC} = \frac{2}{3} \cdot 342.924 \cdot \frac{1 + 0.463 + 0.463^2}{1 + 0.463} \approx 251.6 \, \text{mm}</annotation></semantics></math>MAC=32⋅342.924⋅1+0.4631+0.463+0.4632≈251.6mm
2. Airfoil Characteristics:
   • The Clark YH airfoil is a low-camber, relatively thick airfoil (typically ~12% thickness) designed for good lift and gentle stall characteristics, often used in RC models.
   • You’ve specified “100% thickness at root” and “60% at tip,” which I interpret as the airfoil thickness scaling (i.e., the tip airfoil is 60% of the root’s thickness). This suggests a thinner airfoil at the tip, reducing drag but potentially affecting stall behavior.
   • From airfoiltools.com, the Clark YH has a maximum thickness of about 11.7% of the chord at the root. If the root chord is 342.924 mm, the max thickness is: <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mn>0.117</mn><mo>⋅</mo><mn>342.924</mn><mo>≈</mo><mn>40.12</mn><mtext> </mtext><mtext>mm</mtext></mrow><annotation encoding="application/x-tex">0.117 \cdot 342.924 \approx 40.12 \, \text{mm}</annotation></semantics></math>0.117⋅342.924≈40.12mm At the tip (60% thickness scaling): <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mn>0.6</mn><mo>⋅</mo><mn>40.12</mn><mo>≈</mo><mn>24.07</mn><mtext> </mtext><mtext>mm</mtext></mrow><annotation encoding="application/x-tex">0.6 \cdot 40.12 \approx 24.07 \, \text{mm}</annotation></semantics></math>0.6⋅40.12≈24.07mm Relative to the tip chord (158.756 mm), the tip thickness is:<math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mfrac><mn>24.07</mn><mn>158.756</mn></mfrac><mo>≈</mo><mn>15.2</mn><mi mathvariant="normal">%</mi><mtext> </mtext><mtext>(slightly thicker than the root’s 11.7%)</mtext></mrow><annotation encoding="application/x-tex">\frac{24.07}{158.756} \approx 15.2\% \, \text{(slightly thicker than the root’s 11.7\%)}</annotation></semantics></math>158.75624.07≈15.2%(slightly thicker than the root’s 11.7%) This suggests a complex thickness distribution, so I’ll assume you mean the airfoil is scaled proportionally, maintaining the Clark YH shape but with reduced thickness at the tip.
3. Washout Purpose:
   • Flying wings rely on washout to ensure the wingtips stall after the root, maintaining pitch control during high-angle-of-attack flight.
   • The swept planform (31.3°) already provides some inherent stability due to the rearward shift of the aerodynamic center, but washout enhances this, especially for a Clark YH airfoil, which has a relatively sharp stall.
   • Typical washout for flying wings is 1–3 degrees, with higher values for slower, more stable flight and lower values for faster, more agile models.
4. Flight Characteristics Assumption:
   • Since you didn’t specify the intended flight profile (e.g., slow soaring, aerobatic, or high-speed), I’ll assume a general-purpose RC flying wing for stable, moderate-speed flight (e.g., 10–20 m/s).
   • The Clark YH airfoil is well-suited for such applications, with a lift coefficient range of ~0.2 to 1.2 (based on airfoiltools.com data at Re ~100,000–200,000, typical for your wing’s chord and speed).

Washout Recommendation​

• Washout Angle: For a flying wing with a 31.3° sweep and Clark YH airfoil, a washout of 2 degreesis a good starting point. This provides:
  • Stall control: The wingtips will have a lower angle of incidence (by 2°), delaying tip stall and keeping the root (near the centerline) lifting longer.
  • Stability: Enhances pitch stability, critical for a tailless design.
  • Performance: Minimal drag penalty while maintaining good lift distribution.
• Rationale:
  • The 31.3° sweep already shifts the aerodynamic center rearward, reducing the need for excessive washout.
  • The Clark YH airfoil’s gentle stall characteristics (from airfoiltools.com data) suggest a moderate washout is sufficient.
  • A 2° washout is common for RC flying wings of similar size and planform (e.g., Zagi or similar designs).
  • If you’re flying at lower speeds or want extra stability, you could increase to 2.5–3°. For faster, more agile flight, reduce to 1–1.5°.

Implementation​

• Applying Washout: The washout is a linear twist from root to tip, with the wingtip’s leading edge rotated down by 2° relative to the root. For your wing:
  • At the root (chord = 342.924 mm), the angle of incidence is set to your desired reference (e.g., 0° or slightly positive, like 2–3°, depending on your CG and reflex).
  • At the tip (chord = 158.756 mm), the angle of incidence is reduced by 2°.
  • The twist is distributed linearly along the semi-span (482.5 mm).
• Physical Twist:
  • For a 2° washout over a tip chord of 158.756 mm, the vertical displacement of the trailing edge relative to the leading edge at the tip is: <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mtext>Displacement</mtext><mo>=</mo><mtext>chord</mtext><mo>⋅</mo><mi>sin</mi><mo>⁡</mo><mo stretchy="false">(</mo><mtext>washout angle</mtext><mo stretchy="false">)</mo><mo>≈</mo><mn>158.756</mn><mo>⋅</mo><mi>sin</mi><mo>⁡</mo><mo stretchy="false">(</mo><mn>2</mn><mi mathvariant="normal">°</mi><mo stretchy="false">)</mo><mo>≈</mo><mn>158.756</mn><mo>⋅</mo><mn>0.0349</mn><mo>≈</mo><mn>5.54</mn><mtext> </mtext><mtext>mm</mtext></mrow><annotation encoding="application/x-tex">\text{Displacement} = \text{chord} \cdot \sin(\text{washout angle}) \approx 158.756 \cdot \sin(2°) \approx 158.756 \cdot 0.0349 \approx 5.54 \, \text{mm}</annotation></semantics></math>Displacement=chord⋅sin(washout angle)≈158.756⋅sin(2°)≈158.756⋅0.0349≈5.54mm So, the trailing edge at the tip is raised (or leading edge lowered) by ~5.5 mm relative to the root’s airfoil orientation.
• Construction:
  • If building from foam or balsa, twist the wing during assembly to achieve this angle, ensuring the root airfoil (Clark YH at 100% thickness) and tip airfoil (scaled to 60% thickness) follow the 2° twist.
  • If using a molded wing, incorporate the twist into the mold or jig.
  • Verify the twist with a protractor or incidence meter during setup.

Additional Considerations​

• Center of Gravity (CG): For a flying wing, CG is typically at 20–25% of the MAC, measured from the leading edge at the root. For your wing:
  • MAC ≈ 251.6 mm, so CG ≈ 50–63 mm from the leading edge at the root.
  • Adjust CG and reflex (upward elevon deflection) to balance the wing after setting washout.
• Reflex: The Clark YH airfoil may require slight reflex (elevons deflected up 1–2 mm) to counteract negative pitching moment, especially with washout.
• Testing: After building, test-fly at low speed to confirm stall behavior. If the wingtips stall first (sudden roll), increase washout to 2.5–3°. If too sluggish, reduce to 1.5°.
• Reynolds Number: At a chord of ~250 mm and speed of 15 m/s, the Reynolds number is: <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mfrac><mrow><mtext>speed</mtext><mo>⋅</mo><mtext>chord</mtext></mrow><mtext>kinematic viscosity</mtext></mfrac><mo>≈</mo><mfrac><mrow><mn>15</mn><mo>⋅</mo><mn>0.25</mn></mrow><mrow><mn>1.5</mn><mo>⋅</mo><mn>1</mn><msup><mn>0</mn><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></mfrac><mo>≈</mo><mn>250</mn><mo separator="true">,</mo><mn>000</mn></mrow><annotation encoding="application/x-tex">Re = \frac{\text{speed} \cdot \text{chord}}{\text{kinematic viscosity}} \approx \frac{15 \cdot 0.25}{1.5 \cdot 10^{-5}} \approx 250,000</annotation></semantics></math>Re=kinematic viscosityspeed⋅chord≈1.5⋅10−515⋅0.25≈250,000 The Clark YH performs well at this Re (per airfoiltools.com), supporting the 2° washout choice.

Final Answer​

I recommend a 2-degree washout for your flying wing, with the wingtip’s angle of incidence reduced by 2° relative to the root. This translates to a ~5.5 mm vertical displacement at the tip’s trailing edge. This washout ensures stable flight and gentle stall characteristics for your 965 mm wingspan, swept, tapered flying wing with a Clark YH airfoil. Adjust to 2.5–3° for slower flight or 1–1.5° for faster, more agile performance after test flights.

If you have more details (e.g., intended speed, weight, or CG placement) or want me to refine the calculation, let me know!

 

[TheDaringPilot]

I refined the washout conversation with Grok by giving it the estimated weight and motor, battery, esc, combat type, etc. We both settled on a sweet spot of 1.7 deg of washout, (to keep the airspeed during combat). Estimated flying weight is (800g - 1000g). Grok recommends slightly more washout for a wing that’s overweight. It originally recommended (1.5 deg - 3 deg) washout. Too much washout will result in sluggish control. So slightly above 1.5 deg is 1.7 deg. It also recommended more washout for beginner pilots. When in combat you need to be experienced at the controls to get anyone. So 1.7 deg seems to be the sweet spot, especially since the original Versa wing plans didn’t include washout.

The airfoil has been slightly modified because the points it used to plot didn’t result in a smooth wing. I added a spline sketch that closely matches the airfoil. It slightly adds to the airfoil’s thickness in front of the root which increases the lift of the wing and reduces stall.
Nobody wants a rough airfoil when 3D printing!

First pics of flying wing in CAD coming soon.

 

[TheDaringPilot]

Got the wing design down! Now time to add ribs, servo holders and holes!
It barely fits on my Lulzbot Taz Workhorse print bed! (280mm x 280mm)

 

[Flyingshark]

I hope you're able to get this in the air by FliteFest, this is a cool project, and it would be really neat to see it in combat!

Do you have a specific material in mind for the 3D printed version? Most of the filaments I've worked with are pretty heavy compared to foam board and/or wouldn't survive impacts with other planes and the ground

 

[TheDaringPilot]

I hope you're able to get this in the air by FliteFest, this is a cool project, and it would be really neat to see it in combat!

Do you have a specific material in mind for the 3D printed version? Most of the filaments I've worked with are pretty heavy compared to foam board and/or wouldn't survive impacts with other planes and the ground

I just started the ribs and hopefully will be done with the design by the end of the week.

I was thinking of Polymaker Polymax PC for extra durability and heat resistance. The other option is PETG. I don’t dare try PLA because the plane might need to sit in the car and bake lol. Also Flite Fest is hot!

I made a nose cone out of PETG last year for FF and it survived crashing 4 times! I probably will use PETG just because all things break at some point and PC is sometimes difficult to print. But PC is incredibly tough!
I know that there is LW filament but it’s way too delicate for combat. I’m expecting the wing will be overweight. Flying weight probably closer to 1000g. Original plans 800g. I believe the wing does have a slightly thicker airfoil than the stock Versa which should help give enough lift.

 

[TheDaringPilot]

Update:
The wing ribs are complete. I haven’t had a chance to get a picture but I will tomorrow.
One problem. The wing did not turn out in the Cura slicer properly. It has totally random spots where there isn’t material deposited.
In Fusion 360 the model is really clean but it just doesn’t turn out in the slicer!
I could really use some help with getting my Cura slicer to print out the whole thing! I’m using vase mode. It doesn’t have problems outside of vase mode.
For the ribs I used 0.1mm thickness and cut the wing with the ribs using the combine tool. I followed this (

) video on designing a wing but I think its something to do with my slicer or rib thickness.

I’m happy to share the STL test file that gave me problems if anyone is interested in helping.

 

[TheDaringPilot]

Here is the STL file.

 

[TheDaringPilot]

I found the issue was the wing spar holes. They didn't turn out in Fusion 360.

 

[TheDaringPilot]

Here is a photo of the ribs currently.
I think I'm done with them. Estimated flying weight is 900g.

 

[bisco]

looking good!

 

[TheDaringPilot]

Printing it already! Trying to print in Polymaker PC max but since I have no enclosure and the pieces are huge, it decided to warp and delaminate. I could use PLA but I’m worried about it melting in the heat. I think I’ll try PETG and see if it is rigid enough to hold the airfoil’s shape.

 

[TheDaringPilot]

Will use poplar wood dowels 5/16” ~ 8mm and BBQ skewers 4.5mm. For wing spars and support.

 

[Mr Man]

Maybe put a cardboard box over it as an enclosure?

 

[TheDaringPilot]

Maybe put a cardboard box over it as an enclosure?

Might be a fire risk. Bed temp is 95c and nozzle is 265c. Also the material PC absorbs moisture and that is a problem because I dont have the proper dryer. Moisture can cause warping and other problems. It is also a pain to dry PC because it takes 6 to 8 hours to dry. I'm in a rush to get it done before FF.

 

[Mr Man]

Might be a fire risk. Bed temp is 95c and nozzle is 265c. Also the material PC absorbs moisture and that is a problem because I dont have the proper dryer. Moisture can cause warping and other problems. It is also a pain to dry PC because it takes 6 to 8 hours to dry. I'm in a rush to get it done before FF.

👍👍

 

[quorneng]

"Will use poplar wood dowels 5/16” ~ 8mm and BBQ skewers 4.5mm. For wing spars and support."
Have you considered that rather than adding wood spars simply printing more material in the appropriate places in the skin of the wing may give more strength and rigidity for the same weight?

 

[Piotrsko]

Have you considered that rather than adding wood spars simply printing more material in the appropriate places in the skin of the wing may give more strength and rigidity for the same weight?

Probably above his pay grade

 

[TheDaringPilot]

"Will use poplar wood dowels 5/16” ~ 8mm and BBQ skewers 4.5mm. For wing spars and support."
Have you considered that rather than adding wood spars simply printing more material in the appropriate places in the skin of the wing may give more strength and rigidity for the same weight?

I did think of that. But the wing needs rods to hold it together. I will use duck tape to hold the wing sections together in case I need to repair it. So if there is no rods, there is no support other than duck tape. The wing would flex and the sections might fall off if I only used 3D printed spars.

Update:
I am completely done with the wing design and currently printing the 5th piece out of a total of 8 pieces just for the wing alone.
More pics coming soon.