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May 29, 2018, 04:39 PM
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Build Log

Jas 39 Gripen 1/10


About a year ago I decided to give it a go to design and 3d print a edf model. I started out with a Su-27/30 in mind, but as the modelling progressed it turned out that fuselage would be quite much heavier than I calculated with, meaning that the model would be more or less a brick in the air with the resulting wing load. A little sad as the CAD model was almost finished, but hey.

So, what other models are there that have bigger wings? Living in Sweden, actually just a couple kilometers away from the Saab plant where they build and test fly the Jas 39, said plane came to my mind. Doesn't it looks like it has way bigger wings than the SU27/30? Doing the math, and yes, it does have a considerable larger wing area compared to the Sukhoi. It will still be heavy, but the wingload figures are closer to "a fast edf" than "a stone with a edf attached to it".

Said and done, many dark winter nights were spent modeling, considering that I'm not especially good at this thing with complex surface shapes.

Unfortunately, almost finished with the fuselage and ready to print, I remembered that I like nice details. Such as retractable landing gear >_< Buying retracts doesn't really fit in the book of a "completely" 3d printed plane, so I was stuck with modelling a complete set of retracts, incl a steerable nose one, doh... However, I doubt that these will handle a rough landing very well, so my initial plan is to use them only during takeoff (and for show, of course ) and then belly land on some nice soft grass.

A landing gear and a couple of month later (wife+kids+house+job makes the progress sloooow), I could finally start to print

I printed the fourth section today, and the plane is actually starting to take shape. Very satisfying
If anyone think that they could do something fun with a more or less complete CAD modell of an RC SU-30, I'm happy to send a .stp file
Last edited by evolve; May 29, 2018 at 04:48 PM.
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May 29, 2018, 07:23 PM
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TyberJV44's Avatar
Nice, what are the dimensions and edf size?
May 30, 2018, 01:58 AM
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Approximate specs;
Length: 1400mm
Wingspan 840mm
Takeoff weight: ~2000g
EDF: 70mm
ESC: 70A
Battery: 2x3s packs in series
May 30, 2018, 04:11 AM
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union1's Avatar
Fantastic job Evolve! (no pun intended!)
Do you plan on making the files available for others to print (maybe for a small fee even)
I'd be very interested in doing something with your Su-30 files. I've done quite lot using a 3D milling machine for cutting models in foam and would love to give your Su a go.

Pete
Latest blog entry: SR-71 for 2 x 70mm EDF
May 30, 2018, 06:07 AM
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You got PM with CAD file for the SU-30 Pete! A milled sukhoi would be really interesting to see

And I'm hoping that the end result of the 39 will be satisfying enouth that I can share it without being ashamed for it.
May 30, 2018, 06:16 AM
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Lynxman's Avatar
Nice Gripen model. Are you printing single extrusion walls?

Check out my 3D printed project: https://www.rcgroups.com/forums/show...6-5-scale-L-39
May 30, 2018, 06:40 AM
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Lynxman, that's a really nice plane you have built, I'm impressed! Looks like you landing gear will handle alot more load than mine too

The plan was to use single extrusion outer surface, but I didn't have soo much luck with it. I ended up doing something inbetween, I set the extrusion width to 0,25mm (still using 0,4 nozzle), making the the slicer (Simplify3D) create two perimiters for a 0,46mm wall. This way, the inner structure doesn't interfear with the surface finish, that was my problem with a single wall. The result is actually surprisingly good.
Last edited by evolve; May 30, 2018 at 03:13 PM. Reason: I ment extrusion width, not nozzle diam.
May 30, 2018, 06:41 AM
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Lynxman's Avatar
Good idea. I'll have to try that myself.
May 30, 2018, 09:17 AM
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Dirty Dee's Avatar
Very cool! I have a 3D printed A330-300 planned as a project this year and will be attempting to make it in ABS as PLA isn't the best in hot weather.

Very clever tricking the slicer with the nozzle settings, I also need to test it myself.
Jun 05, 2018, 04:31 PM
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Another 34hours of printing and section 5 is done!
I'm really surprised with the reliability of this printer (Wanhao duplicator i3+). I haven't counted hours but an estimate based on the number of prints x average print time is that it has been squeezing out plastic for about 300 hours without a glitch. Okay, not completely without a glitch, but noting that has created any downtime.

However, it starts to resemble something that looks like an aircraft Slightly heavier than I was aiming for, but still manageable. The now completed part of the fuselage ended up at 600g, which means about 1300g total fuselage weight (incl wings).
Jun 05, 2018, 07:31 PM
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TyberJV44's Avatar
Way of the future. Looks good, will you be 3D printing the wings as well?
Jun 06, 2018, 09:27 AM
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Lynxman's Avatar
I use the same CA glue from Biltema. Unbeatable value for money.
Jun 06, 2018, 01:23 PM
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Quote:
Originally Posted by Lynxman
I use the same CA glue from Biltema. Unbeatable value for money.
Good stuff
I really like using CA with activator as I can fixate one point with a small spray and then focus on aligning the rest.
Jun 12, 2018, 05:02 PM
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Another section printed, two to go on the fuselage (Last section not glued in the pic, hence the missalignment)
I have printed a wing too, but need to do some more experimenting on the attachment between the wing and fuselage. The tolerances were apparently too tight so the wing could not slide property on its rail. There will be some trial and error to find the sweet spot between too tight and too sloppy.
Jun 12, 2018, 05:21 PM
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Lynxman's Avatar
Looking good!


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