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Completely 3D Printed Mini Mustang

#1
After building (and crashing) a foam board Mini Mustang, I got the idea to try to print one. I'm very near to being ready for the maiden flight - the last 3D printed piece is about half an hour away from done, and then it's just stuffing the electronics in it.

Here's the progress so far:
jHEs6n.jpg


Please excuse the aesthetics on the prototype; it hasn't been the focus ;)

I've been making adjustments to the CAD as I've been putting together the prototype; namely adjusting tolerances, adding mounting points, fixing the warp on the ailerons, etc.

The biggest thing to note is that this thing is heavy. I think once it's ready to fly it'll be around two pounds. I'm hoping with a Power Pack F it'll still manage to maintain a better than 1:1 thrust to weight ratio, but who knows!

If I do future 3D printed designs, I'm probably going to take a much different approach to it. Since this design is built to foam board specs, the walls are 4mm - probably totally unnecessary. I could go down as low as 2 or even 1.2mm and still have good durability. I also wouldn't need big flat surfaces (nearly every piece is designed to be printed standing up), which would let me match the aesthetics of the actual plane it's based on much more closely.

I'll also seriously consider doing more of a hybrid design with a foam wing and 3d printed everything else. The wing was the most time consuming thing to print and adds a lot of weight. In addition, between the fuselage and the wing, the wing is way faster and easier to build in terms of foam. Unless this thing has shockingly good durability (which it might, considering the carbon fiber spar I put in it), the tradeoffs just don't seem that great in favor of 3D printing it. The current design on the 3D printed fuselage has a hole a tad too small to use the FT Mini Mustang wing though, unfortunately. I will probably adjust that.

Once I take it out for its maiden, I'll release both the CAD file and the STLs for printing it. Happy flying!
 
#4
Awesome job! I’m also working on some 3D printed FT designs. Couple questions...

1. What slicer are you using? I’m using simplify 3-D Since it is the only one that I can get to print thin walls successfully.
2. Are you creating custom ribs or using infill?
3. Have you tried static thrust testing? I usually hold my plane vertically by the tail, and run the motor up to see how much weight it relieves.

I’m looking forward to see how it does in flight testing.

JG
 
#5
I was hoping to get this done Wednesday but I had one heck of a time getting this new-fangled S6R to bind to this new-fangled Taranis QX7. But after trying everything in the book and a little extra, I finally got it binded, so I'll be plopping in the electronics tonight. Gotta have it ready for the weekend!

More pics soon!

Awesome job! I’m also working on some 3D printed FT designs. Couple questions...

1. What slicer are you using? I’m using simplify 3-D Since it is the only one that I can get to print thin walls successfully.
2. Are you creating custom ribs or using infill?
3. Have you tried static thrust testing? I usually hold my plane vertically by the tail, and run the motor up to see how much weight it relieves.

I’m looking forward to see how it does in flight testing.

JG
1. Cura 1.5.x, as that's the one recommended for (or at least distributed with) the MonoPrice Maker Select Plus printer I have (aka Wanhao i3 Plus). I used to use slic3r when I had a kit Prusa i3, but I find Cura works a lot better. I'll get around to updating my settings to use Cura 3.x .... eventually.

2. Using 10 to 15% infill depending on the part. That said, there is a carbon fiber tube acting as a spar in the wing. This baby ain't bending no way no how ;) I think if you're willing to put in the time and effort though, ribs would probably work better. Like I mentioned in the OP, there are a looooot of design choices I'm going to do differently for future designs - 3D printed plastic is pretty fundamentally different than foam board, so building the plane according to specs from foam board plans leaves a lot of room for improvement. I could drop a heck of a lot of weight off this build without really sacrificing any strength by reducing the wall size from 4mm to 2mm (or even less), for example.

3. Not yet, but I shall! Had a lot of trouble getting the receiver binded for the first time.
 
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localfiend

High Alpha!
Mentor
#6
Cool man. Awesome to see somebody else playing with fusion 360 to make 3D printed planes. Starting out with a proven FT design is a pretty good way to go for a first attempt. A proven air-frame shape should do well if you can keep the weight down.

I have a feeling what you're got is going to be a bit difficult to deal with in the wing loading department. But it sounds like you're already thinking about version two.

At the mini mustang size I can pretty much guarantee that a carbon spar won't be needed to keep the wings strong enough in flight, the 3D printed plastic will be more than strong enough. The way you've got it built though, I'm thinking it will survive a pretty hard crash though. :D

I've got a couple of my own designs in progress right now. I'm using 3Dlabprint's planes as inspiration and am making all my own custom internal supports. You can get a lighter stronger product that way than with infill.

If your version 1.0 ends up too heavy you can go that route. You already have the solid bodies for the entire plane, you just need to make spars to go inside what you have.

This plane is gigantic, so your internal structure wouldn't be nearly so dense or complex. All the internal bits (spars, fitment aids etc), are separated from the outer surface of the plane by .8mm. This lets you print with a single outer perimeter without errors, excessive stringing, or excess weight while still ending up with a an air frame strong enough for flight.







Here's the build thread for the above if it's of interest. Probably should have posted it inside this forum section.

http://forum.flitetest.com/showthread.php?38420-3D-Printed-Hughes-P21-J-Devastator
 
#7
Oh man, your Fusion 360 skills are on a whole 'nother level than mine, haha. Thanks for the tips!

Yeah, weight, and as a byproduct balance, is turning out to be a huge issue. I ended up sticking a couple 1oz weights in the front just to get the cg even remotely in the right place, and it's still not-insignificantly far off. I'm hoping the stabilization on the S6R will help compensate, but there's an equal chance that'll totally blow up in my face aha. Weight management is #1 on the things to keep in mind for future designs. Also yeah that carbon fiber is probably totally unnecessary, I bought it before putting anything together :p

Related, RIP any chance of a 1:1 thrust to weight ratio. I'd estimate I'm around 0.75:1 now. Oops.

New pix as promised:
6s7jFt.jpg
Notch in the canopy is to accommodate one of those mini FPV cameras.

Gotta wire up the aileron servos and touch up some settings on the tx/rx. Most likely gonna put landing gear on it since I don't think hand launching will fly (pun intended) with such a low thrust to weight ratio. After that, it's p much ready for maiden this Saturday. Not sure if I have high hopes, but I do have high hopes that version 2 will be much better from everything I've learned making this one :D

Also, due to the coincidence of running out of grey filament and printing the tail in white, I've decided to name it "Fox Tail" after these fellas
YzrGEo.png

If Fox Tail survives the weekend, she gets a paint job ;)
 
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localfiend

High Alpha!
Mentor
#8
Oh man, your Fusion 360 skills are on a whole 'nother level than mine, haha. Thanks for the tips!
It's not so much skill as time spent on the model. If you've got the basics down, which you seem to, you can do something the same way. :D


Yeah, weight, and as a byproduct balance, is turning out to be a huge issue. I ended up sticking a couple 1oz weights in the front just to get the cg even remotely in the right place, and it's still not-insignificantly far off. I'm hoping the stabilization on the S6R will help compensate, but there's an equal chance that'll totally blow up in my face aha. Weight management is #1 on the things to keep in mind for future designs. Also yeah that carbon fiber is probably totally unnecessary, I bought it before putting anything together :p

Related, RIP any chance of a 1:1 thrust to weight ratio. I'd estimate I'm around 0.75:1 now. Oops.
I don't want to be a downer, but if it's that heavy, and still hasn't reached the balance point, you may want to skip flying this one and go straight to version 2.0. Unless you find value in spectacular crashes. Something I have to admit is often quite entertaining. :cool: Crashing my stuff always makes me laugh.

The FT mini warbirds are very CG sensitive. The acceptable CG range for any plane goes down the smaller your plane is, and a high wing loading makes it even worse. If you're determined to try a flight and don't mind risking your electronics, make sure it balances first. It will be better to have the correct CG and a lot more weight than be lighter with a tail heavy plane. The stabilization inside your RX probably won't be a help, and will likely be a hindrance if it isn't perfectly tuned, especially if it's tail heavy.
 
#9
I agree, but I’m in to spectacular crashes! LOL

Go get e’m and here’s to v2.

JG

PS with F360’s would anybody be interested in collaborating on a specific airframe? Might be fun to try.
 

localfiend

High Alpha!
Mentor
#10
I agree, but I’m in to spectacular crashes! LOL

Go get e’m and here’s to v2.

JG

PS with F360’s would anybody be interested in collaborating on a specific airframe? Might be fun to try.
I started on an F6F Hellcat a few weeks ago with the intention of making it into an open tutorial. It's not a super complicated plane but there are enough complex features I thought it might make for a good learning tool.

Got to get the Devastator done first though, or it won't get done. I'm bad about procrastinating. I'll start another thread so this one doesn't get hijacked.
 

bhursey

The Geeky Pilot
#11
Wold theses be powered by the same size quad motors as the foam ones? LOL need some small 3d printed planes as my cessna 152 is hugggggge...
 
#12
Oops forgot to update the thread lol.

As predicted, it was pretty tail heavy, and I had already added so much weight to the front to try to balance it that the thrust just wasn't enough.


However, version 2 is coming out quite nice thus far!

6C02JQ.jpg
dJQebw.jpg
 
#13
I started on an F6F Hellcat a few weeks ago with the intention of making it into an open tutorial. It's not a super complicated plane but there are enough complex features I thought it might make for a good learning tool.
A tutorial for Fusion 360 centered around plane design sounds mighty helpful! I didn't even know about the loft tool until after I finished printing version 1 :rolleyes:

I also just found the "inspect center of mass" tool and material properties that let me set weight so I'm gonna model in the electronics as well so I can get a good estimate of the CG BEFORE I print it this time
 
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localfiend

High Alpha!
Mentor
#15
Haha. Yeah, that flight went as expected. Always fun anyway, for me at least lol.

I like the way your version 2 is looking. More scale and you're looking to save some weight as well.

If you want, and don't mind sharing the fusion file with me I can quickly add some internal supports to the model for you to look at and perhaps copy throughout the rest of the model. It 's not super complicated, and I think I can help you shave off a pretty good weight percentage. Or at the very least, you could see what I'm doing and and take those concepts for version 3, or your next plane.

If you want to share something and not have it get messed up by another use, a good way to do so is make a new project folder, and save a version of your file into it. That'l make a completely separate copy. You can then invite people to the project folder who can look at or modify the files inside. My Fusion 360 account is localfiend@hotmail.com.
 

bhursey

The Geeky Pilot
#16
Suggestion I have is to extend the nose out to help with CG without adding to much more weight. That's what they did in the 3d print lab cessna. Well mabye scoot the wing back some?
 
#17
Oops.



Don't put your print in the oven to cure resin faster when your oven will only go as low as 170°F. Bad things happen.....

That's like 25 hours of printing and a quarter of a roll down the drain. Sad sad sad
 
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#18
Oh yeah, should probably post these first -
z9dCFvm.jpg
ChbjwPU.jpg
XRbkYLT.jpg
KobnHQo.jpg

Design is p much done apart from as-I-go changes. Until the incident a few minutes ago, things were going pretty darn well :p

It's definitely lighter by order of magnitudes, but still pretty darn strong. I have much higher hopes for this design.
 
#19
First of all nice 3D printing skills.

Second: Someone really needs to come up with a self foaming 3D printing filament or something similar to print foam objects..........and soon! ;)
 
#20
That got me curious and apparently you can actually print foam

https://3dprintingindustry.com/news/now-can-3d-print-memory-foam-34265/

Problem is it's not rigid foam, but rather something more akin to memory foam. But it's that's possible, maybe printing rigid foam is too. Someday!

I'd have to design it a lot differently and I definitely don't have the tools to do it, but a present-day idea would to be to print out a prototype, make a mold from it, then inject mold a foam version of it.
 
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