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Proteus - an OpenSCAD slope soarer design

by spinorkit Feb 6, 2017
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ahha found it, in some of your youtubes it says Sandymount and when I googled it, it says it's in Ireland. Hence I thought that was where you live, but even so, I am still envious of where you fly

I desperately want to print the larger version and with a rear motor mount, but I am restricted to a 210 x 210 x 205 print area of my Anycubic i3 Mega, and as an old fart I don't know the first thing about cad programs and am too old to learn, is there some very helpful person out there that can cut each piece of this plane in half and re upload them to me so that I can then increase the part size in Cura to end up with the larger plane. Being on a disability pension means that buying a printer with a bigger build volume is out of the question. I would be most grateful to any person that is willing to help me out

Hi Barry,
If you can wait a week or two, I have just finished printing a 1.8 m version of this .
The maximum height required to print the parts is 200 mm (the wing has 8 sections not including the tip fins). I have not flown it yet.

I have written an option in the Openscad code for a fuselage with a rear mounted motor, but I have not yet tried printing that for this particular configuration, hence the delay.

The aerofoil is the PW51.

that will be awesome mate. As I said, I really do appreciate both, your work and your willingness to help others out, you really are a true gentleman and I look forward to the new 1.8 mt version as before my accident all my planes were over 2mt wingspans, and I really miss them since selling them all and now fly quads and small electrics, and want something bigger so yeah, I can wait a week or two. Again, thank you.P.S. I am very envious of where you live and fly, the fun I could have there would be immeasurable

Hi Barry,
I am working on the motor version of the 1.8 m Proteus Plus, but in case you are interested in something smaller and quicker to print, I just noticed this:

Proteus with motor mount an z max 183mm - Remix

thank you Kit, but I am happy to wait for the 1.8mt version, do you have any files for the front or wings that I can start printing until you finish the rear motor part

My intent is that the wings will be the same as for this:
They should be ok, but bear in mind I have not had a chance to fly that yet. The nose will be longer. I would like to put a RunCam split camera in the nose if possible.

Proteus Plus PW51

Kit, is the nose that is in the plus version correct or will you be altering it to accommodate the camera. Just so I know if I can start printing the nose or still have to wait, I will be fitting a cheapish camera but there is enough room already for mine. I don't want to print the nose and then find that you are going to alter it and it not fit the motor style rear

Barry, I will be modifying the nose. The problem is the battery and the camera both have to completely fit in the nose, since the spar joiner is in the way and just behind the nose section. My intent is to set the processor board for the RunCam Spit into the roof of the nose above the battery, held in place with Duo Lock, with the camera in front of the battery. I will probably need to increase the height of the fuselage as well as the length of the nose. I need to program models of the battery, the processor board and the camera to see how to fit this all in. Then there is the worry about the CoG with all that weight in the nose. Gliders are much simpler!
I am aiming for a powered glider not a rocket ship, using a small motor (D2822 or D2830), 1500-1800 MAH 3S battery and folding prop.
I attach stls for a proposed fuselage with no camera to give you an idea of what it would look like. I have neither printed this nor tested the fit for a battery.
I would print the motor mount in PET, ABS or nylon. My intent is to change length of the motor mount to achieve the correct CoG.
I have limited the height of the rear fuselage to 204 mm.

Kit, in answer to your question re flying rear mount planes, I have the FX-79 Buffalo, which is the 2mt wingspan equivalent to your FX-61 and also the series 2 Volantex Raptor, as well as a diy launcher that utilizes a length of speargun rubber and small parachute.
I live in an area that is mostly wheat farming and as such I get some excellent thermals so this "powered glider" type plane is very well suited to me as I can get long flights on a smaller battery because I use the thermals to assist the motor and not rely on motor power alone.
Can you tell me where the COG should be and what throws I should set on the control surfaces initially

ok that is good to know, so I will just continue printing wing parts for the time being. Are you aware that the 4 control surfaces are all a different lengths, is this by design? as I would have expected only two different lengths not all 4 being different.
My days of powered rocket ships are far far behind me, my reflexes are just not quite what they used to be, so a large powered glider is exactly what I was looking for

I have only provided the left hand flap and elevon, since you can make the right hand ones by mirroring in the slicer. The flap and elevon are slightly different lengths and each comprised of 2 pieces that need to be glued together with a 2 mm OD CF rod and CA glue, after a little sanding of the mating ends.

what is it that you younger guys say. Duh! or is it Doh I think thats it from memory of what my son always said, mimicking Homer Simpson. I didn't realise that it was a case of each control surface being in two peices

I had over looked the fact that the original Proteus did not need this, so I have now added a sentence describing how to join the pieces to the "Thing Details" for the Proteus Plus.

At 60 I'm perhaps not so young.

Bugger, I should have taken a closer look at the CF vitamins before starting to build this plane, after checking all of Aliexpress and E-Bay i can't find anywhere to by just 1 length of each of the different sizes of flat, round and tube. Everyone wants a minimum order between 5 and 16 lengths and upwards of $26 freight for each supplier, so I am going to have to print the main body when you upload it, and then mothball the plane until I can figure out what I am going to do with all the leftover Carbon Fibre, that is after I save enough money to purchase it in the first place. This was going to be the last plane I ever build as after this one I will have nowhere to store any more

Sorry, it seems the shipping cost has gone up by about a factor of 2 or 3 since I bought my supply of CF strip a couple of years ago. I got a range of sizes all 1 m long from the same supplier (and asked for the shipping to be combined) because I was not sure what would work best. Since the shipping cost depended on the length not the weight, it seemed quite reasonable then. The actual price of the CF seems to have stayed constant.
Also, for me the CF cost is pretty small compared to the kilograms of PLA+ and Polyflex I waste prototyping these designs - I always seem to make stupid mistakes that I don't catch until I have printed the part, and getting the tolerances right can also be tricky.

oh well, the last piece of the wings is rolling off the printer in about 2 hours so I will be dropping back here every afternoon to see if the main body pieces for the pro plus have been uploaded. I am on a disability pension and my wife is stage 4 terminal cancer so money is a hell of a lot tighter than it used to be when it was nothing for me to blow a few hundred on a new 65cc 2 stroke engine for my piper cub or some other thing, plus the aussie dollar is so low in value I pretty much need to pay double and triple what you guys pay once the $$ exchange rate is factored in

well friend I am the same age, so your doing alright considering.
I am on so much medication for pain, that my brain struggles. So much that you can't teach this old dog new tricks like using CAD software or like my other hobby robotics using arduino, so I rely on really great people like yourself to do the hard work, so I don't have to, but one thing is sure and that is I appreciate yours and everyone elses help

Ok thank you Kit, I will start printing the wings and if you can let me know when the fuselage with motor mount is ready, it will be most appreciated.

Comments deleted.

spinorkit can you please share solid version of the model, there is no chance that i can do any changes to the shell body. is that possible for you?


Hi demirdemir,
I don't know what you mean by "solid version".
This an OpenSCAD design. You can download the complete source code in the .scad files under the "Thing Files" page.

It was not designed in SolidWorks or a similar CAD system.


Thank you for the response,

I have downloaded all the files, however all the parts seem to be shell and i cannot edit them. I have tried catia, solidworks and keycreator all of these programs recognize the files as shell not a solid body which can be edited. Hope i have described it well. I have also downloaded scad and tried to modify it there but the program hangs every time i have tried it. Is there any chance that you can save it as solid body not shell so i can modify it further?


The stl files are exported from OpenSCAD and are basically solid apart from cut-outs for spars etc. That is why you have to print them with a very low infill percentage. They are not shells.

I don't know how to export them any other way.

Stinger is 150cm. I think Im trying to run before I can walk. I will build the Proteus as standard and then look to modifications. I can see that increasing the sweepback makes the wing tip mounted fins moment arm longer and increases their effectiveness . But I have found tip mounted fins very vulnerable. I need to use a longer fuselage than you with my single central mounted fin. I came across a very intresting article on full sized aircraft see attachment.

Thanks for the interesting document.
The first versions of Proteus had flat plate fins which kept breaking on fairly ordinary landings.
Much to my surprise, I have only broken one fin of the blended NACA foil fins ( after a 40 m plummet into the ground tip first as result of a spin-out from a loop).
But I have not tried DSing.

Hi , Reducing the sweep would allow a one peice spar to extend to the wi g tips which controlls wing flex. The Pw51 airfoil is one I have had some success with .I have attached a photo of my battered "Stinger" .It is made from EPP foam, with a spar made from two carbon golf shafts joined with a tool steel bar. it.weighs 1.5 kg without ballast I have managed 110mph dynamic soaring my local welsh mountains. I am primaly interested in speed . I must admit its a bit of a pig to loop. I realise that a printed sloper may not be up to the rigors of DS ( printed with carbon impregnated filament? ) It would be interesting to compare different accurately made airfoils on otherwise identical models

Ok, that makes sense, for DS you will want to control flutter well!
What is the span of your "Stinger"?

I have some carbon impregnated PET. It is stiff but brittle.
I find PLA+ printed at 240 C or more and layer thickness > 0.2 mm to ensure good layer adhesion is the best. PET is brittle for shock loads and ABS warps too much for large structures.
With PLA+ I rely on printing single layers thin enough (0.4mm) that they flex rather than cracking.
With weight not being a problem you could print a double layer skin with infill between the layers to increase the stiffness but still have some shock absorbing capacity.
You might not need the spar going all the way to the tips. A single spar doesn't do much to prevent the tips fluttering in a rotational mode.

Hi wou,d it be possible to easily change the airfoil to PW51 by replacing the data in the MH-45.scad file? Also reduce the wing sweep back?

I had a quick go at this, but the code needs some additional changes to make it handle the reduction in the thickness of the aerofoil. At the moment I have no free time to do this, although I am very interested to do it.

I am curious why you want to reduce the sweep?
Increasing the "tail moment" by increasing the sweep slightly in the Proteus V2 greatly improved the handling characteristics, at least for slope aerobatics.

Can you put cura settings? Infill and Shell? My pieces are too heavy.

Hi, I too used Cura with my Series 1 3D printer and printed heavy wing parts. While re-reading the printer settings here, tweaking Cura params, test print, and re-reading printer settings here, repeat, I think I figured out the proper Cura settings in Expert-Basic Mode. Here is what I used with Cura 1.5.0

Layer Height: Wings 0.24 and the rest 0.2
Shell Thickness: 0.4
Bottom/Top Thickness: 0.72 (Since 3 Layers was called for in S3D for this project)
Infill Type: 3D
Infill Distance: 13.8 (This gives us the 2.9% overall infill in this project's description)
Extrusion Width: 0.4

With above params, resulting number of shells is 1, infill is 2.9%, bottom thickness consist of 3 layers, and top thickness consist of 3 layers.

Thank you very much for providing this information!
I have a few questions though, as someone who does not use cura.

I wonder why you set the Bottom/Top thickness to 1.2 mm when 3 x 0.24 = 0.72 mm?

I am not sure what "3D" infill corresponds to in cura 4.0.0, but I see that "Cubic Subdivision" seems to be very light. Light enough to increase the infill % up to 5%, perhaps.

Note that the most important way I reduce the weight of the infill is reducing the "Infill Line Width" to 0.29 mm, down from the 0.4 used for the walls.

Thanks spinorkit for pointing out the error in Bottom/Top thickness. You are right about 0.24 and the thickness should be 0.72 I mistakenly used 0.4 when calculating the thickness. I'll adjust the post above.

Cura 1.5.0 "3D" infill is actually "Cubic" in later versions. It has greater density than "Cubic Subdivision."

Also thanks for clarifying on the infill weight reduction. There is definitely a difference when reducing "Infill Line Width" vs just changing overall infill to 2.9%. Cura 1.5.0 doesn't let me change the "Infill Line Width."

I will upgrade to the newer version of Cura as it supposedly supports the Series 1 and then use your print parameters.

I have not used cura for many years, but I just installed version 4.0.0 to have a look. After turning on the expert settings, for a wing section I would set :

Layer Height: 0.24 mm
Line width: 0.4
Wall line width: 0.4
outer wall line width: 0.4
Infill Line Width: 0.29
Initial layer line width: 150%

Wall thickness: 0.4
Wall line count: 1
Top layers: 3
Bottom layers: 3

Infill Density: 4 to 5 %
Infill pattern: Cubic Subdivision

Note I have not tried printing with these cura settings. They are based on what I use in S3D, but cura does not have the "fast honey comb" infill I use in S3D, which is very light and provides just the right amount of support to the skin.

Hello, I have a question as you had made it. What about if you join the parts together with small possible screw or M3 screw rather than joining them with glue. As it will held the parts strong together and I think that with the even screws on both sides will keep the plane balance. As a result less chance of it to break.

What do you think about it.

Hi, most of the joins are simply taped together, as I said in the instructions, "The only pieces I glue together are the nose to the rear fuselage and the servo guards to the wing (both with thick cyanoacrylate)". Screws are generally more work and make the structure weaker than tape because they concentrate shock loads at small points rather than spreading them over a large area. Tape also has some elasticity and reinforces the surface around the joins. It is hard to beat fiber-reinforced tape for making robust joins. Believe me, I have crashed this plane enough times to know!

Hi, I do not know in which side position I should print the Finns, maybe you have a tip?

One of the images is a screen shot from Simplify 3D showing how the fins are placed on the bed for printing.
This also shows the support I add (manually) at the trailing edge.
I have just moved this screen shot so it is now the 5th picture in the list of images/videos above.

Thank you for your prompt answer! :)

Hello, please help, I do not know how to get from the model stl that will be divided for printing, the enclosed parts stl contain only the left part. Please send someone STL for a complete airplane?

Hi, you can create the right-hand parts by reflecting the left parts in your slicer. E.g. for Simplify3D, chose Mesh | Mirror Mesh | Mirror X (or Mirror y).

Two times lucky, I managed to get my Proteus up in the air again :-) A challenge as I had to choose a small motor and a big battery to get the CG right, resulting in a ship a little too heavy. Very nice to fly once in the air, very fast and it looks so good! Thank you Spinorkit! Description on my Make Site -
and in the YouTube video:

Proteus - an OpenSCAD slope soarer design

Thanks for sharing!
Nice scenery, great flying, beautiful landing!

Very nice model , I want to print the motorglider version
I looked to the available modified fuse rear but it seems to me that the hole in the fuselage is to small for the motors cables , moreover the room inside the fuselage looks too small for 3s 2200mA battery , receiver , esc and connectors , I want some room to move the battery foreward just in case the model get tail heavy , so I would like to make a few changes.
I am not using openSCAD but FreeCAD and I would like to make the changes using this tool..
FreeCAD opens the OpenSCAD files if saved in csg format , can you be so kind to save the Proteus in this Format ?
Many thanks

I'm sorry, but OpenSCAD does not support exporting .scad files to csg format as far as I can tell, so I don't know how to do this.
Does FreeCAD support importing .scad files?

FreeCAD should be able to open files from OpenSCAD , when I set the function import FreeCAD shows the supported format , among them OpenSCAD csg format.
Anyway I printed the fuselage size 200 , front and rear part , the rear part is the motorized version , the Zippy battery 3S 2200 mA desn't fit in the fuselage too tight at least 3 mm more hight and wide are needed to let the battery slides freely in position , second I placed the receiver the fuselage is nearly full there is no room for the ESC.
The fuselage size 230 has the same dimensions, isn't it ?
I tryed also another way , import in FreeCAD STL files which are mesh and than transform in solids , but unfortunally this procedure works well only for simple shapes .

Comments deleted.

Does someone has factory files? Is it supposed to fit in a standard 220x220x220 printing volume? Looks like wing root exeeds 242mm hight.

The wing parts print on a 200x200 mm bed if you align them along a diagonal using your slicer. The parts with names ending in 200 need a z height of 200mm while those ending in 230 need a 230mm z height.

Hi spinorkit, I printed a motorized version with the remixed fuselage from halfliterpete and it flies great. Thanks for sharing the Proteus with us.
I read somewhere about a larger Proteus v2. How is it coming along?

Many thanks for the tip. Much appreciated, I'm glad your motorized one flies well!
The bigger version is called the Proteus Plus, has a 1.6 m span and flaps. I was just flying it today actually. I am just waiting to get some decent video before publishing it. It's a bit slower, especially with the flaps down, easier to fly and better suited to lighter winds, but a bit more fragile.
I have been experimenting with the design to get it a bit more robust. For quite some time I have been using a fuselage printed completely out of semi-flexible (and therefore indestructible) Polymakr Polyflex.
It uses 2 carbon fiber strips swept back like a V for a spar, along with a 3D printed spar joiner. This joiner takes up quite a bit of room in the middle of the fuselage, so it would need significant changes to the shape and size of the fuselage to fit a battery for a motorized version.
Would you be interested in using it as a glider?

HI there! I would be really interested in the Proteus Plus as I only fly gliders.
I live near the coast in New Zealand and we have fantastic slopes!
Where can I find the prioject?

That sounds great, especially the bit about the flaps and the greater wingspan.
As I am living in a flat region, I would again be interested in a motorized version.
If you could manage to incorporate a motor mount and space for a battery into your design it would be awesome.
I am looking forward to see a video of the Plus in action!

Is anyone else having a problem where the fins are not attached to the wingtips? When I render them, the blend section is missing so the fin is disconnected from the wing tip. The attached screenshot shows the wingtip on my slicer.

I've not used SCAD before so am probably missing something basic and any pointers would be much appreciated. Thanks

Does it look alright in OpenSCAD after rendering with F6?
Are there any error messages in the OpenSCAD console after rendering with F6?
What version of OpenSCAD are you using?
That blend section is quite sensitive to the parameters and it is fairly easy to set parameters that cause error messages in OpenSCAD.

Thank you for responding, spinorkit! I am using OpenSCAD v2015.03-2 on Win64 freshly installed for this purpose.

The render shows the same discontinuity - it isn't as easy to visualise in the graphic so used the slicer graphic.

Rendering just the tip, the console window reports as in the attached text file. I note that there is an error reported but really don't understand what it is telling me!

ERROR: Alternate construction failed. CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: e->incident_sface() != SFace_const_handle() File: /opt/mxe/usr/x86_64-w64-mingw32.static/include/CGAL/Nef_S2/SM_const_decorator.h

That version of OpenSCAD is not able to render the blend section.
I just tried the latest development snap shot 2017.11.12 and it fails as well.

So you will need to download this version (which works for me):

Thank you again. That does seem to be working - testing now.

I did wonder when the latest version I could find had 2015 in the name! :-)

Do you know whether this will change anything else on the model? I've rendered and started printing the other parts and would rather not redo them but if this will change the dimensions then I'd rather start again and redo them all with the same version.

I would be very surprised if the dimensions or shape changed with the version of OpenSCAD.

Thanks again, spinorkit, for your assistance - and also for producing such a wonderful model! :-)

My motorized version with "ArduPilot":
Soon i release this remixed project with the enlarged fuselage...

Thanks for sharing the video.
Can you fix the link though? I think it should not have "edit".
Looking forward to seeing the remix.

Hi Macro,great flying!
What technique did you use to launch it?
What battery size, motor and prop?
A Make or Remix with photos would be interesting.

I launch it just like any other delta wing, like this one:

2A 30C 3S Li-Po battery, 6x4 propeller, 2212 1200 Kv motor.

Thanks for the video Marco.
So you use full throttle for the launch?
I normally fly slope soarers, so I don't have experience launching a pusher with the motor running at a flat field.

Hi spinorkit, i would like to try to automate the Proteus with "Ardupilot" but i would have some needs, keeping the same printed wings:

  • double the width of the central body (from 120 to 240mm)
  • slightly raise the central compartment (10/20 mm) and extend it by at least twice, for install the flight control, gps and others
  • stretch the nose 50mm

I tried but the result is not good, could you please correct it by keeping those dimensions in the file?
Canopy support in the rear fuselage is not good and and is too thick, and i can't position well the antenna holes.
Can you help me?

Hi Marco,
I hope to do this in a few days time, hopefully by this week-end.
How high does your printer go?
Have you printed wing sections with printerMaxZ = 300 yet?

I succeeded the resize but I had to remove the "duoStrips", I can't place it properly, but anyway I want to find an alternative way to fix the canopy.
However, I can't make the canopy stretch even in the back, I only succeeded in the nose.
EDIT: another improvement, much better with "noseFlatness = 1.5".

Did you try making the hatchAngle more -ve, e.g. -6 degrees?
The reason I chose duoStrips instead of magnets was because I thought I might one day put a Pixhawk controller in and I did not want to disturb the magnetometers.

Now i think the only problem is the "duoStrips", can you fix it for me in this version?

Yeah, with "hatchAngle = -6" is much better!

The external and internal dimension of my fuselage version It's exactly what I want, but i need to enlarge the dimension of the canopy, just for reference see the red line box, and the back fuselage does not give me the right support for the canopy with my resize parameters.
I need all this space to work comfortably inside this enlarged fuselage.

Did you print your existing wings with printerMaxZ = 250, rather than printerMaxZ = 230?
It's late here, I can't finish this tonight.

By the way, have you tried setting partToGenerate = ""; and using F5. It is ugly but fast for adjusting things like the hatch.

Hi Marco, I just uploaded a (rather hacky) modified version of your doubleSize fuselage file, which may work for you.

I print my wings with "printerMaxZ = 230".

Comments deleted.

Yes, full throttle!

Dear spinorkit, great design, thank you!
I almost finished printing the "230" version (motorized version).
For this reason i'm trying to stretch a little the nose, I added 50 mm, and the result is perfect:

noseLen = 140;

Original is "90".
Unfortunately the hatck does not stretch properly after rendering it, it remains too short.
Where is the problem?
How i can modify the hatch in OpenSCAD code to respect the correct resizing?


Hi Marco,
I have just uploaded a new scad source file (to Thing Files) that should allow increasing the noseLen parameter and still result in a hatch that fits.
The new scad file is called ProteusFlyingWing.scad and replaces CustomizableFlyingWing.scad (which I have left on Thingiverse because it matches the uploaded fuselage and hatch stls).
I have not yet printed either a fuselage or a hatch generated from this new code.
Unfortunately, I doubt the new hatch will fit your fuselage. You will probably need to print a new fuselage rear and possibly a new nose.


Hi spinorkit, thanks for the new scad source file.
By stretching the nose 50mm when rendering I find this 2mm hole (in the red circle) not centered in "FuselageRear" and "FuselageNose".
With the original value (90) it doesn't happen.
So stretching the nose the fuselage becomes thinner in the lower side, can you fix this?

Hi Marco,
I have just replaced the ProteusFlyingWing.scad file with a new version that should result in the fuselage joiner hole being centered better vertically as the noseLen changes.

spinorkit, great contribution thank you. Almost all printed now, and yet to fly. LOVE the OpenSCAD app & your file, took me a little bit to teach myself the language (just enough to be dangerous!), but managed to extend the nose and pump out each of the new part exports. Reason I extended the nose and widened the internal space was to accommodate a larger battery & balance the CG for a powered version.
Only problem I've found is the HATCH.
It fits properly but is too short on the aft end. It now doesn't actually overlap all the main rear section, it ends short, leaving a gap and no place to put the velcro retainer. Can you hint what parameter/lines I could change to get a longer Hatch please.

FYI -- my build log

Hi, this is a nice project ! I just sarted up to print this plane all in abs i dont know if it will fly but i got an complete left wing and it seem good ! I read that you fly with 685G so my goal are to not go over 585G!!!

PS. sorry for my english

Thanks! I am impressed you have managed to print a wing in ABS. I thought there would be too much warping for such large parts in ABS.
Is your printer enclosed( to keep the heat in)?

Yeah i Got an enclosed ! I dont know how to post à picture check those link

I only have only "glue" (with acetone Juice ) the wing section , no finition have been done . I really like ABS its really malleable with acetone tricks.

But what about inter-layers bonds? I like ABS, but my case shows thing I print from ABS are much less stiff in between of layers :( But maybe acetone juice cures this?

Great idea using foam for the enclosure! What temperature does it reach inside?

After some comments at YouTube I finally finished one with motor ( Its performance is amazing, even with braking propeller (beautiful planes mostly fly well - confirmed!). With the extra weight (motor etc.) it is very stable without yaw wobble discussed before. The question is if not to sacrifice some performance to get more forgiving flight characteristics - stall is an one way ticket to the planet Earth without any warning, which is worse with higher flying weight of motorised version. But you have what you paid for - the glide is perfect and as spinorkit wrote, it is not for beginners.
Thanks for the design!

Proteus with Motor Mount UNTESTED!

Thanks for the comments Dan. I have not noticed the stall being severe while slope soaring, despite flying it slowly at times while scratching for lift. Perhaps the yaw wobble has warned me off before I reached it! I have got it into a spin to the ground a few times when pulling too much up elevator in a loop.
Also, I fly with the CG on the dimples, which is fairly well forward I guess.
I am interested in details of the stall(s) you experienced.
Was it during straight and level flight, a turn, or a loop?
Did it tip stall into a spin?

I experienced stalls leading to spin several times in level flight after I tried to pull too much, and also at higher speeds in an attempt to loop with insufficient energy. COG was 2 mm (?) to the back, but it flew nicely without single beep at elevator trim so I kept testing. I wanted to shift COG slightly forward, which I think would surely help (maybe at a cost of slightly worse glide), but the last spin was unintentional and shifted COG to values that could not be measured anymore :-). I was really surprised by the performance it showed in my configuration. I want to try the original slope version (which is lighter by at least 100g) and a folding prop (which needs some mod to limit flapping blades to avoid their collision with wing trailing edges) for motor version.

I am also interested in making a version with a folding prop. I have not yet found a suitably small folding prop/motor combination so I would be interested to know what you decide on, not being expert in matching electric motors to props. When I get time I am aiming to do a version of the fuselage with a hollow tube motor mount with air vents near the nose, and at the rear of the tube, for cooling the battery and ESC.

Regarding the drive train, I decided to use what I have found in a drawer... 1400 kV motor ( and 8x6 prop ( The actual spinner diameter is only 31.5mm, but still a bit big for the motor and motor mount. I had to protect the wing with this: (it works better than it looks...). ESC is YEP 30A, set up for automatic timing and hard brake, battery is Zippy 1300mAh. This all gives 760 g static thrust at 11200 RPM and 19A (this is really low, but Agilent current probe said that). I tried not to bother with cooling holes (except four small holes in the motor mount that fit holes in the motor back plate) and surprisingly both the ESC and battery stayed just slightly warm in a hot day, partly due to reasonable motor/glide time proportion. Total flying weight was 685g, which I think could be reduced - e.g. by the use of weaker and lighter drive components.
I think something like this (there are versions with different kV available) would be OK since the ESC cooling is solved perfectly. It is not easy to find a prop spinner that small (such as Propeller blades should be chosen according to motor kV - both higher kV motors and corresponding bigger props are heavier but more efficient and vice versa. Since Proteus loves speed, props with high pitch are necessary.
A propos, after shifting CG close to the position marked on the fuselage, low speed stalls with spins disappeared, replaced with yaw wobble - exactly as you anticipated. It still needs to be really steered and I was able to do some high-speed stalls, but it is OK - it is a plane, not a Barbie accessory :-)

Folding propeller blade flapping stop
by maxad

Dan,I haven't done the stability analysis in xflr5 yet but I think increasing the sweep from 22 to 25 deg and reducing the taper so that
tipChord = 0.8*rootChord; should result in more stability and less propensity for tip stalls. This would also increase the area of the fins.

This is a simple change in OpenSCAD, but you need version 2017.01.20 which means going to the download page and scrolling way down to the development snap shots section. I have only tried the 64 bit version.

In case you are new to OpenSCAD:

Run the Openscad installer.

Then copy all 5 .scad files from the Proteus download into a folder of their own.

Double click on the CustomizableFlyingWing.scad file and OpenSCAD should start.

Choose Design | Preview (or F5) and you should see the shell of the Proteus displayed
Find the parameter tipChord parameter - it is on line 42. Change the 0.65 to 0.8.
Press F5 and you should see the tips widen.

The sweep is set on line 46.

When you are happy with the shape, set partToGenerate on line 22 to e.g.:
partToGenerate = "RootWing";
so that just the RootWing is generated.

Then use Design | Render (or F6) to prepare the stl.
This will take a few minutes.

When it is finished you can zoom in with the mouse wheel and use the buttons along the bottom of the 3D pane to check it looks ok from different angles.

When happy, click the "STL" button in the tool bar to save the stl.

Thanks for the detailed info, Kit. I have already tried to fiddle with the parameters you mentioned - and some others. I left my wings detachable (it is fine if everything incl. Tx fits small backpack) and wanted to make the connection between the wing and fuselage more rigid, so I wanted to use bigger diameter spar for next print. However, after changing the spar diameter to 7mm the spar tube intersects with servo lead tube. I have found that it was not just due to the diameter increase, but also the servo lead tube shifted towards the spar: I admit I was not able to figure out what happened in CAD data, I did not change anything but the spar dia. In addition, when I went through the stl in SkechUp, I noticed that the spar tube support is splitted and does not touch completely the inner wing surface: (this is a slicer output for original STL downloaded from here). Was that done on purpose? It makes the fuselage-wing connection a bit wobbly if not glued together. Thanks for your help or suggestions.

Yes Dan, you found a bug there, no doubt one of many! The spar/servo lead guide separation should scale better with sparD if you change the line around 1478 from:
overSparAngle = atan((servoLeadDepth-sparD+bendPosFromServo*tan(dihedral)+1.5)/bendPosFromServo);
"overSparAngle = atan((sparD/2+bendPosFromServo

  • tan(dihedral))/bendPosFromServo);"

You can check this more quickly by setting partToGenerate = ""; and uncommenting (delete the //) on line 194:
and hitting F5.

The split support for the spar tube is intentional. Cutting a thin slice out from the solid wing section is the means by which I force the slicer to generate a perimeter (i.e. the support) there. That slice also needs to avoid contacting the surface to prevent the slicer splitting the surface along the line of contact.
You could try reducing the slice thickness down from 0.1 mm in the first parameter for cube on line 1061:

Oops, I just realized increasing the sweep will make the wings incompatible with halfliterpete's motor mount fuselage, sorry. I need to get around to doing a motor mount version in OpenSCAD.

I'm very tickled that there is so much excitement and success with my hack! I haven't even flown it. I'm excited to see what a purpose built motor version would look like. Very cool!!!

Thanks for all this useful info and prop guard design Dan.
I assume you meant lower kV motors and correspondingly bigger props?
I've ordered a 28mm folding prop spinner, 7.5 x 4 and 7 x 6 blades, along with a 1800kV motor :

Yes - lower kV with bigger prop, sorry for the typo.

Excellent Design , and a very cool looking Slope soarer , I will print this off and add it to my build list , Thank you for the Share Spinorkit


p.s I think you could design a wonderful DLG that's printable

Thanks Bob!
My longer term plan was to move from flying wings to printing boom-tail gliders in the 1.6 to 2 m range. Do you have an idea what the maximum acceptable weight for a DLG would be?

Well Spinorkit ,
I think if you could keep flying weight if a 1.5m DLG to less than 350 grams you would be heading in the right direction , a bought 1 would be around 280 grams, but I would say that was light and that's why its 400 quid to buy . maybe print it without a skin ?, then use Modelling Film to cover the frame would lower weight of the wing and tail parts, I hope you do a thin wing aerofoil dlg size because it could be used for many models. Good Luck m8 , I really do hope your successful.

              Kind Regards  

Beautiful design and nicely arranged I think. I'm printing it now with a Tronxy X8 acquired last week and very impressed with print quality.
Prints looking great in clear and grey PLA. Hope to finish and fly in a couple of days.
Will let you know.... Thank you spinorkit.

Thanks Bruce, I'm looking forward to seeing some photos!

Just letting you know I have now added what I hope is useful information on printing temperatures, cutting carbon fiber, and control throws, to the Thing Details.

Does this design requires any mechanical motors or any thing like that
can you please tell me that which all parts need to be printed if i want to print one of these
i am really confused that which parts need to be printed

This is a glider, so in its original form (in the video) it has no motor for propulsion, just two servos for moving the control surfaces.
The fuselage has been modified (not by me) to accept a motor here:

The parts you need to print depend upon the maximum height your printer can print to.
If it can print as high as 230mm or more, print the parts with file names ending in 230.
If your printer cannot print as high as 230mm, but can print to 200 mm, then print the parts with files ending in 200.

If you have not setup and flown a R/C aircraft before you should go to a flying site and ask an experienced flier to test it out for you.
Better still, buy or build a foam or foam-board plane or wing to learn to fly with before attempting to fly this one.
This wing is definitely not suitable for learning to fly with.

Proteus with Motor Mount UNTESTED!

Love the design. Stupid question but what about the right wing sections? There are only left stl's

Just mirror the left wing

Thanks! Most slicers have an option to reflect an imported stl. In Simplify3d, it is under the Mesh menu. Choose mirror x or mirror y to convert a left stl to a right stl.

I'm very excitied when I thing about capabilitie to make this :)
It's really fly without motor? It's like gliter?

How did You design aerodynamics?(if I would like to make by myself) Can You propose some tut or book?


Yes, it is a glider with no motor.
It flies a bit fast for thermal soaring so it needs a steep slope with a wind of at least 8 knots to provide lift.

This website has a lot of information (and links) about designing gliders:

The best way to learn to fly a slope soarer is using a simulator such as this one:

This driver software lets you connect your R/C transmitter to your PC's sound card as a joystick to control the simulation:


Thx for answer.

I dont know german so I hope will make Yours. Will see. But I have a question. Can I put one or two motors in the back(on center)?


I just posted this...

No guarantees.... Untested.... Give it a try!

Proteus with Motor Mount UNTESTED!

I really like your work and would like to print that plane, but my printer only supports 160mm Z level.
Is there any chance you are going to upload modified parts which fit my printer?

I've tried to modify it myself but Solidworks isn't able to import .stl files and I'm quite a loser in Openscad.

It would give me great pleasure if you could help me :-)



It will take some work to achieve that. One problem is that the elevons will need to be printed in 2 pieces and glued together and they are pretty thin, but it should be possible.
I will start working on this, as time permits, but I won't be test printing those parts, so you need to be ok with doing the first test prints and possibly finding errors!

What are the complete build dimensions for your printer?


I have a printer with a 600mm x 600mm x 600mm build volume. I'd be interested in making a larger version of this sailplane that could take advantage of this vertical height., maybe one designed for 500mm high. I'm thinking that if making it any larger, I might run into other issues with warping or sticking to the bed. Do you have any advice? I have a few questions for you about printing a larger plane.

Do you have any plans for making models for a larger version?

If you had a larger printer and were making this same scale plane, would you combine any of the pieces?

If I wanted to scale up the STL files for a larger plane, which features need to remain the same size? I assume the hatch and battery holder cavities, the CF tube diameters, etc.

Any other changes, such as more weight in the nose?

Beautiful design by the way. Great job.

Wow, a printer that size certainly gives you lots of options and thus raises lot of questions!
I have been thinking about longer span planes, possibly using carbon fiber strip spars instead of tube.
Longer spans necessitate wing joiners for transport.

If I had a printer as big as yours I might try printing the wing root and tip in one piece (without the fin). It would get pretty tall and thin, but I notice your printer has a stationary bed so that may not matter.
Increasing the root chord would increase the warping forces, but then there is more area to stick to the bed so hopefully it would be ok. Increasing the height shouldn't cause any greater warping problems than the existing pieces have.
The main problem with simply scaling the stls (assuming you could get the correct diameter carbon fiber tube and rods) is that the servo cut out would no longer work . It would be much better to download the .scad files and adjust the parameters in OpenSCAD.

By the way, my printer goes to 250 mm height, but the reason I have stopped at 230 so far is that the standard servo leads would no longer reach the fuselage, so I would either need to solder longer leads on or make the lead conduit much wider so it could handle a plug (which is problematic because the conduit crosses above the spar and there is not much room).

One other important point - to transport this in a car on a sunny (Californian) day you really need a white box, perhaps made of coreflute and/or polystyrene foam to put it in. I left 2 of these in my car in the (New Zealand) sun for about 1 hour and even with the windows down a little bit, all the non-white PLA pieces were pretty much ruined.

If you keep the same sweep angle and increase the span, the center of lift moves back, so you might not need more nose weight.

If you let me know the sort size you would like to print, I can try tweaking the OpenSCAD code to cater for some larger options.


Thanks for all the great information Kit. Unfortunately I don't know OpenSCAD. I would love to print one that would use pieces scaled up for 500-550mm. If you scale them up, I'll print it. I'm thinking I should print the 230mm version first and then do the larger one. A friend of mine that used to build sailplanes moved to New Zealand. I'll send him the 230mm version when I make the bigger version.

Thanks again,

I have some ideas for a scheme for changing the design to use swept carbon strip spars instead of a straight carbon tube spar. This will remove many of the constraints on the design parameters and should make it possible to have spans of 2 m or more and higher aspect ratios.
There is quite a lot of work involved and I have little spare time, so it would definitely be worth practicing with the 230 version in the meantime.
Shipping the 230 version in pieces in the "untaped" state is certainly very practical.


Very nice model. Thanks for your citation about the instiration on my GASB One .
Your model flew better and without battery :)
I'm very happy to see your works and thanks again

GASB One - RC Flying wing fully printed (ONLY 9 PIECES GLUELESS)

Hi Carlo,
thank you for your great designs (and videos) which showed me that 3d printed airframes could be made to fly (and land) well!

Wonderful job. I'm so glad to see some honestly well-designed planes like this hitting Thingiverse. I'm working on some designs myself but am 3D CAD challenged so I appreciate the thought into developing airframes like this.

Thanks for your encouraging words! I learned a lot about OpenSCAD while doing this. Unfortunately, most of the code was written quick and rough before I knew better ways to do it, so there is a lot to improve!
While I find OpenSCAD a bit painful to use for a project this large, I have yet to master any other CAD tool well enough to do this sort of thing. Writing code suits the way I think and gives me a sense of being in control.
I built my printer 3 years ago and was skeptical about printing airframes with it. I was expecting a million pieces after the first heavy landing, but while it can't match the robustness of EPO foam, it flies much better than most foam wings and has survived some bad crashes with either no damage or minor damage requiring 5 minute repairs with cyano and/or tape.