Tailless DLG - Hybrid construction

[Gadeirus]

Right, so, since I'm waiting for a new ESC to show up to continue on my speed challenge designs, I decided to design something else using some small(ish) electronics I had already puchased a while back for a different build idea.

I'm trying my hand at building a plank/tailless DLG using hybrid construction of 3D printing, DTFB, and some carbon sprinkled in for good measure.

I've never designed or even flown anything lacking a horizontal stabilizer so this may very well end in disaster, but I've learned a lot about designing in the process and am trying out some new (to me) ideas.

I've named this one "FlingWing" because I'm just infinitely clever and creative like that

Span is 1,050mm, roughly 14.4dm^2 area, Solidworks is predicting a flying weight under 200g, so we'll see if I can make that happen. Elevon control only. Using PLA for all things plastic, a 1m long 5mm hollow square carbon tube for a wing spar, and DTFB for the wings and vertical stabilizer.

Few screenshots:

I'll start posting the build in the next post.

 

[Gadeirus]

I've built and flown several models already using 3D printed fuselage pods etc. though always modeling exact wall thicknesses and so on. This time I'm trying the more "normal" way of doing it, namely thin walls and light infill but otherwise "solid" parts.

Here are all of the plastic bits printed off, using white PLA because that's what I had at hand. If/when I build another one I'll be sure to order something more colorful. Approximately 4 hour print and everything easily fits in one go. Since I've been super skeptical about using a single wall and infill like so many people do, I printed with 2 walls and 5% gyroid infill. Parts are pretty light and I'm pleasantly surprised by the strength, this gives me a lot to think about for some...other...airplanes I've got partially designed.

Battery slides into a pocket in the nose, works pretty well though I've already got an idea or two to improve this even more:

Part of the wing hold down scheme, a large nylon hex nut in pocket and then a cover plate CA'd over top:

Here you can see the remainder of the wing hold down set up. A central "spine" for the wing that has some fingers that hook into slots in the fuselage pod. The large boss in the spine is where a flat-head nylon screw goes through. There's also a square hole that the carbon wing spar slides into.

You can kind of see what I've got going on for the vertical stabilizer, too. There's a separate plastic piece that will be bonded into a notch in the foamboard stabilizer, and then that whole thing can be slid into the back of the fuselage pod and fastened with some M3 nuts and screws. Not entirely sure why I went through the trouble of doing this, though I like to think that the stabilizer is most likely to take damage during a landing so this way (in theory) I can replace that more easily.

Another new thing I'm trying is canopy attachment since I always seem to struggle with this. As you can (maybe) see, the fuselage pod is grooved and the canopy has flanges at the bottom that slide into them. There is also a small spot on canopy and fuselage pod for magnets that will be CA'd in place once they arrive. Works pretty well so far, it's a little too loose, need to tighten up my clearances a bit.

Test fitting electronics. May have to rob a servo from something else. I ordered a few more but it's going to be a while before they show up, unfortunately. I also made a hole/tunnel for the Rx antenna, you can see the antenna sticking out the bottom.

Little 4-channel Radiomaster Rx I bought, it's quite small and light. Should have measured and modeled the Rx up myself. I found someone else's model of it and it's not quite right, therefore the inside of my fuselage is a little too narrow to get it to fit the way I want. That's what I get for being lazy, I suppose. There's a "trough" of sorts that runs underneath the receiver area for me to run servo leads through. I only have one in there at the moment, and it looks like I'll be able to get a second through without much trouble. So far the canopy still fits over all of this no problem, pretty happy how this is all working out so far.

That's all for tonight. I've got my drawings printed out and taped together already so tomorrow I can start cutting foamboard. As an added bonus, everything fits on a single sheet of DTFB.

Only things I still need to procure are a can of 3M77 spray glue I want to try to use to laminate sheets for the wing, and then something to cover the wings with. I'm keen to try some laminating plastic, but if I can't find something like that locally I may just use packing tape or something.

 

[Bricks]

Finding CG will be interesting nice work.

 

[Gadeirus]

Finding CG will be interesting nice work.

Yes, agreed! In CAD it looks spot on, but I'm not going to trust in that. After I had already started gluing the fuselage together I realized I had meant to design in some space for weights so that I could adjust CG.

I've run into enough little things I'd like to change already during the build that I may just go ahead and make those changes and print another.

 

[Gadeirus]

Yeah, went ahead and modified the design. Tweaked a few things, knocked 25mm of length out of the tail, and added a pocket below the battery to put some weights into. Not my favorite solution, but it'll do without having to do a bigger redesign, it's printing now.

 

[Gadeirus]

As luck would have it, I still had a bunch of bright orange filament, so I used that.

You can see the tail is 25mm shorter now. I opened up some parts of the inside some more so now the Rx fits better and the servo leads can be routed a little easier. Snugged up the canopy fitment some, added a pocket for weights under the battery area. Another fun (to me at least) thing I added was a little wedge shaped cutout under the battery, so now the battery can be slid forward, then if you push down on the end of it with your finger it will tip up, making it even easier to get out.

 

[Gadeirus]

Magnets showed up today

 

[Gadeirus]

Not done yet but we're getting there.

Going to have to make a new elevon, I broke one during sanding. On the other wing half I did the sanding first, will cut the elevon off afterwards.

Relatively happy with how the wing is turning out. Profile sanding sucks, not enjoying that, but between the carbon spar and the fiber reinforced tape it's shaping up to be decently stout. Working on covering the whole thing in packing tape, too.

 

[Gadeirus]

So, at this point really just waiting for some servos that I ordered to show up, install those, and it'll be mostly ready to go.

The wing and vertical stabilizer are completely stripped of their paper and covered in packing tape. What I should have foreseen is the utter lack of torsional rigidity of the elevons when doing this, they are now very limp noodle and I need to fix that issue before attempting a flight.

I also haven't yet bothered to add a throwing peg, I'm going to wait until I can try some hand launches to see if it's even remotely close to being capable of flight.

 

[telnar1236]

Magnets showed up today

Magnets and 3D printing work really well together - with foam the plane flexes in flight a lot and the magnets can come loose, but with how stiff 3D prints are, it feels like the work a lot better