Has anybody printed something like this?

[Geeto67]

So I don't own a 3d printer but I am what you would call 3d printer curious (meaning I really want to get into this but haven't the funds or the first idea where to start). I was scanning through Thingiverse today and I saw this:

https://www.thingiverse.com/thing:2622604



I also saw this one:
http://www.instructables.com/id/Biplane-10-300S/

I have casually seen these types of airplanes before, 3d printed skeleton structures, in my google searches but I have yet to see one actually built up or flying. I'm not talking about those skinned ones from 3d print lab, those planes are nice and all but heavy and complex due to the sheer amount of plastic.

Does anybody have any experience in building a model this way?

how do you get film to stick to it? How do they fly?
how do they compare to conventional balsa or even the foamboard planes?
how do you keep warping to a minimum?

this seems like there is a lot of potential here but I just don't see it much in use.

 

[jhitesma]

Well, the thingiverse one would be unprintable as is. At least on a common FDM printer (basically all desktop 3D printers). You could probably do it with a stereolithographic printer or powder bed printer..but those are far less common and way more expensive.

I haven't tried building any traditional structure but printed in 3D plastic planes since really it seems kind of silly to me. The plastic is going to be heavier than balsa and accuracy isn't going to be as good. Not to mention the potential issues of attaching covering and how well it holds up.

It just doesn't seem to be well designed for the materials at hand. Planes are built out of wood that way due in large part to the engineering requirements of wood. The requirements of plastic are considerably different and the 3d labs prints approach makes a lot more sense to me.

 

[Geeto67]

I haven't tried building any traditional structure but printed in 3D plastic planes since really it seems kind of silly to me. The plastic is going to be heavier than balsa and accuracy isn't going to be as good. Not to mention the potential issues of attaching covering and how well it holds up.

It just doesn't seem to be well designed for the materials at hand. Planes are built out of wood that way due in large part to the engineering requirements of wood. The requirements of plastic are considerably different and the 3d labs prints approach makes a lot more sense to me.

I don't know that I agree with these statements. The plastic has a very high tensile strength for it's weight and I think the weight difference is the key. The 3d print lab airplanes I think illustrate this perfectly in just how heavy they are compared to a comparable size balsa airplane. The trestle design in the ultimate bipe link I posted seems to actually be the better way to build this - use the benefits of the strength of the plastic through geometry rather than just using more material (like balsa airplanes do).

Can I ask what experience you have printing airplanes? people are covering these airplanes so I don't know that the covering is really all that much of a problem, just something that requires a different technique due to temp sensitivity. I was kind hoping for people with first hand knowledge to weigh in, not naysayers and doubting Thomases.

 

[LitterBug]

Geeto67,
I have thought about taking a balsa plan, 3D printing it, and building it just for fun. Have not made it past the thought process yet. If nothing else, it would make a nice display piece in my cubicle at work. It would not take much work to print some test pieces up to compare weight density, strength, etc... Might make for an interesting project to build balsa and printed versions of the same plan for comparison purposes. It is a shame that it is getting difficult to find balsa kits.

Cheers!
LitterBug

 

[LitterBug]

One other consideration is time to print vs time to cut. Printing parts is going to take a much longer time than laser cutting balsa.... An interesting spin on this would be to build a MPCNC, then print and cut parts from the same plans on the MPCNC. Could certainly reduce the infill on the 3D printed parts to reduce time and weight, but balsa is really going to be hard to beat.

Cheers!
LitterBug

 

[Geeto67]

One other consideration is time to print vs time to cut. Printing parts is going to take a much longer time than laser cutting balsa.... An interesting spin on this would be to build a MPCNC, then print and cut parts from the same plans on the MPCNC. Could certainly reduce the infill on the 3D printed parts to reduce time and weight, but balsa is really going to be hard to beat.

Cheers!
LitterBug

Time is the avenger. However, I kinda feel like the time lost in waiting for a print could be made up for in the assembly phase with the right design. One thing the 3d Lab prints are far superior on it the modular self aligning pieces that click together and then you glue the joint. Think about it like this - if you were assembling a wing you could in theory print three ribs at a time assembled on leading and trailing edge spars with interlocking tabs. Then when you get home (because your printer has been running while you were at work) you just take the printed wing sections and connect them, the tabs cause them to self align. I think that would be quicker overall than building a jigged up balsa wing because it uses background time to print instead of requiring you to actually be there placing every rib.

here is a 3d printed hellcat I found on RC Forums:


I can't imagine this being heavier than the same size balsa equivalent, but look at how much less material is used.

I kinda see the future of 3d printed planes in the hobby going the way of this:


rather than this:


but I just don't see as many people working on the trestle designs over the skinned designs. Maybe it has to do with the time investment, which with my very limited 3d modeling experience and knowledge (3d studio max animation in the 90's) is not all that great a gap. but I could be wrong.

 

[LitterBug]

Well.... the 3D lab print stuff isn't quite as easy as click together. I have a whole lot of time invested in an EASYMAX001 that still hasn't flown. There is still a ton of experimentation that has to be done based on the matierial, printer, color, alignment of the moon when it comes to printing those parts.

The servo and motor mounts aren't very flexible which makes it almost a requirement that you use exactly the parts it was designed around. I have built balsa, and I have printed. The feel of a balsa wing is MUCH better. I do want to try a hybrid approach using 3D printed ribs, carbon spars, and covering with film.

Do you have any plans in particular that you would want to try working with. Since you are here in town, Maybe I could work on the printing, and you could do the building.

Cheers!
LitterBug

EDIT: Actually I see the .STL files in the original post for the instructables one. I'll look at printing them up and maybe we can do a team build on this. It is a HUGE number of parts....

 

[LitterBug]

Actually found another RCgroups thread from Mid7Night, someone who is VERY active with foamboard here on the forums. Here is his initial design and thread: https://www.rcgroups.com/forums/showthread.php?1757258-Design-Print-Fly-3D-Printed-Organic-Design. The recurring theme I see in all of the 3D printed attempts is WEIGHT issues.....

Cheers!
LitterBug

 

[jhitesma]

To be fair I'm not huge on the 3Dlab prints planes. I've discussed the details in other threads about them but basically the way they're designed just doesn't work well for printing for me. They don't slice with slic3r due to funny geometry, and I'm not a fan of Cura which they do slice well because I've never managed to get quality thin wall prints with Cura (but have had no problems getting great thin wall prints with slic3r.) Basically the 3Dlab prints designs have funky geometry to trick Cura into working well, but since Cura and my printer don't get along well I can't print their designs. I've tried a few of their sample parts but have had nothing but trouble with them.

I did 3D print a similar designed plane:

374g before adding motor and electronics.






I built it back in March but didn't get a chance to fly it until just a week ago. I live in the desert and usually fly over hard dirt and rocks which didn't seem wise to fly this over. And the few grassy fields around are usually filled with soccer players. Plus being printed in PLA I was nervous about taking it out in summer since PLA will deform quite easily after just a few minutes in a hot car - and even with the AC going my truck in summer is hotter than cars is most parts of the country

Unfortunately the maiden flight didn't go too well - I had the throws dialed back too far and even with full stick wasn't able to correct for my lousy toss quick enough:



(Click for better video)


I had my wife and daughter along but my daughter is too young to toss this thing, and I had just let my wife try tossing my FT-29 to launch me and twice in a row she threw it down into the nose when she freaked out as I throttled up - so I wasn't going to have her try to launch this one!

But...


Surveying the wreckage there's actually no damage to the printed parts. The only thing that failed were the CA glue joints, the plastic is still fully intact. So...a few minutes with the CA and I should have it ready to fly again. The only CA my LHS had in stock when I assembled it was foam safe CA and didn't seem to bond very well. They've since restocked and so I have as well and will be looking forward to re-gluing it shortly with some normal CA.

I've also built and flown balsa planes though I build slowly and fly seldom since I'm even slower about making repairs! I currently have a plans built RV3 I've been working on for almost 2 years and have actually been thinking about digging in on again since my dining room table is finally clear again due to Thanksgiving so I've finally got room to finish assemblying the wing

I also 3D printed a few small gliders and have build small balsa gliders - which is why I feel 3D printed structure would be heavier than the equivalent balsa structure. Even printed very thin the 3D printed gliders were considerably heavier than similarly sized Balsa gliders.

PLA is generally 1.25 g/cm^3

Balsa is all over the place depending on the grade: http://www.modelaviation.com/balsa

But even the heaviest at 14lb/cu.ft works out as 0.224258 g/cm^3

PLA is not the lightest 3D printable plastic but it is one that has similar structural rigidity to balsa.

PETG is heavier at 1.27 g/cm^3 and less stiff so it's not a great option.

ABS is lighter at 1.07 g/cm^3 but still considerably heavier than balsa. It's also less stiff than PLA and very difficult to print thin without warping.

Nylon is 1.15g so lighter than PLA but still heavier than ABS...but even less stiff than any of the others and still heavier than Balsa.

HIPS is 1.08 - I've never tried it though and don't know how it compares structurally.

HDPE and LDPE are lower still at 0.91-0.97 g/cm^3 but not at all common for 3D printing and not very stiff.

So...yeah...balsa IS lighter than anything you can 3D print.

 

[Geeto67]

Well.... the 3D lab print stuff isn't quite as easy as click together. I have a whole lot of time invested in an EASYMAX001 that still hasn't flown. There is still a ton of experimentation that has to be done based on the matierial, printer, color, alignment of the moon when it comes to printing those parts.

I hear that is a common complaint. I have been trying to look for someone to print a Stearman for me but the people doing it for others are booked, and places like shapeways want too much money and don't want to "adjust" anything.

The servo and motor mounts aren't very flexible which makes it almost a requirement that you use exactly the parts it was designed around. I have built balsa, and I have printed. The feel of a balsa wing is MUCH better. I do want to try a hybrid approach using 3D printed ribs, carbon spars, and covering with film.

I am not gonna lie, I love balsa airplanes too. I am not a balsa snob to the point that other things should be excluded because experimentation is how progress gets made and foam and foamboard has made the hobby way more approachable.

Do you have any plans in particular that you would want to try working with. Since you are here in town, Maybe I could work on the printing, and you could do the building.

I don't have any digital files but I have some old paper plans for a waco cabin biplane and a Mooney M20 that I have been looking at working with in some form. Interestingly enough there are a lot of older "box contruction" airplanes that could probably work well with this once the pieces get redesigned. I would love to work on something with you if for no other reason then to learn how to do this 3d stuff firsthand.

EDIT: Actually I see the .STL files in the original post for the instructables one. I'll look at printing them up and maybe we can do a team build on this. It is a HUGE number of parts....

I think that would be fun.

The recurring theme I see in all of the 3D printed attempts is WEIGHT issues.....

Every material has its own limitations. When I was a kid (1980's) I used to get a lot of old (1950's-70's) Stearling and Peck Polymers kits where the wood had been heat cycled in these tiny cardboard boxes for decades and were brittle as all get out. I had to learn techniques to restore rigidity and moisture to the balsa in a pre-internet environment in order to get anything built because the pieces would splinter and turn to dust taking them out of the sheet. And then I had to battle weight issues and warping with some of those techniques. So balsa is by no means a "perfect" medium, neither is foam board, and neither is plastic. But that doesn't mean we shouldn't try and the only way to try is by doing.

I can tell you one thing I am kind of looking forward to in the future - playing with those materials that can be polished like metal (colorfabb makes it I think). How great would it be if in the near future people in the hobby could print an airplane that under clear covering looks like it has a metal substructure? it would take scale flying detail to the next level. Or mixed media assembly techniques that could make complex wing shapes more approachable.

 

[Geeto67]

To be fair I'm not huge on the 3Dlab prints planes. I've discussed the details in other threads about them but basically the way they're designed just doesn't work well for printing for me. They don't slice with slic3r due to funny geometry, and I'm not a fan of Cura which they do slice well because I've never managed to get quality thin wall prints with Cura (but have had no problems getting great thin wall prints with slic3r.) Basically the 3Dlab prints designs have funky geometry to trick Cura into working well, but since Cura and my printer don't get along well I can't print their designs. I've tried a few of their sample parts but have had nothing but trouble with them....

Much better information, thank you!!!!

I am still not entirely convinced that balsa is lighter in the finished product, even though it is in same size comparisons. I just don't know that the tech is being used in the most efficient way at the moment.

The smaller the airplane, the more sensitive weight is, so for small gliders balsa is superior. But when it comes to a larger airplane, I think you can use significantly less material in plastic than you need in balsa to get the same shapes and strength, and that is where the advantage lies. I'm not talking about huge airplanes either, maybe things as small as 30" wingspans, but probably not smaller.

 

[LitterBug]

I have been trying to look for someone to print a Stearman for me but the people doing it for others are booked, and places like shapeways want too much money and don't want to "adjust" anything.

I think we could work together on this. I love the Stearman and almost picked it as my first print last winter but went with the EASYMAX001 instead. I started a Guillows PT-17 about two years ago.

FYI, despite the Big10 championship game being on Saturday night, I will be going to the Indoor Fly at the Continent Saturday night.

Cheers!
LitterBug

 

[jhitesma]

Much better information, thank you!!!!

I have more time today because I'm waiting on server updates

I am still not entirely convinced that balsa is lighter in the finished product, even though it is in same size comparisons. I just don't know that the tech is being used in the most efficient way at the moment.

That's the key issue IMHO. Using the materials in the most efficient way.

Just replacing balsa with plastic is going to be heavier. So taking a set of balsa plans and just printing the parts in plastic you'll always wind up with a heavier end result.

But that's not using the material to it's best abilities. I think this is what 3D lab prints is trying to do and is IMHO the right approach.

A traditional balsa plane most of it's weight is in the structure and the skin contributes very little weight. The skin does contribute strength though how much varies - tissue doesn't do as much as the various plastic coatings.

With the 3D lab prints planes he minimizes the internal frame and instead most of the strength comes from the skin. Same with the design I printed. But...they still have a good bit of internal structure - more than I suspect is really necessary.

I think the 3D lab prints designs are going in the right direction - but I also think we're just seeing the tip of the iceberg and the next few years we'll see more and more techniques evolve.

I'm not ruling out using a 3D printed frame with traditional covering...but just taking an existing balsa design and printing it is IMHO a very misguided approach. Designing a new structure designed to be printed and to take advantage of the properties of plastic (built in hinges is an obvious start) is the way to go...and something I've yet to see anyone do but am looking forward to seeing happen.

 

[Geeto67]

I guess what I am looking for is the applicability to people looking for scale airplanes and how it can be used to that end. It's much less restrictive to think of it in terms of a non-scale airplane design, but getting a shape that looks like a familiar airplane without the weight penalty - that's the key.

So far the skin method seems to be the way it is going for people to make scale airplanes because it requires much less engineering, much less time modeling, and is approachable, and the penalty is weight. but looking at a 3dprintlab airplane I think there are sections you can cut whole pieces out of the fuselage and wing, cover with thin covering and still have a perfectly flying airplane with no loss of structural integrity.

 

[LitterBug]

Geeto67, If you want a quick example to play with, I could easily finish printing the EASYMAX and get all the printed parts to you. I just need to print the main left wing parts. Maybe once you have an example in your hands you will have a good reference to start with. Printing the others, while not out of the question, would be quite time consuming in comparison.

Cheers!
LitterBug

 

[Geeto67]

Geeto67, If you want a quick example to play with, I could easily finish printing the EASYMAX and get all the printed parts to you. I just need to print the main left wing parts. Maybe once you have an example in your hands you will have a good reference to start with. Printing the others, while not out of the question, would be quite time consuming in comparison.

Cheers!
LitterBug

No worries, and not in a rush. We should meet up and talk about it in person. Do you have any details about the indoor fly? I know the last one was 11/22 but I don't know about the one this saturday.

 

[LitterBug]

Here's the main info page with all the latest details. http://horizonindoor.com/

Cheers!
LitterBug

 

[Geeto67]

I guess I'll see you there. Check your PM's by the way.

 

[LitterBug]

Good meeting you last night at the indoor fly! Been digging around for more examples, here's an interesting 3D printed, covered design:
http://www.circuitgrove.com/products/openrc-swift-freeopen

This is more along the lines of what I've been thinking about trying with an old balsa design. Kind of a hybrid 3D-print, Carbon spar, and possibly even some balsa stringers.

Cheers!
LitterBug

EDIT: OH the irony. He covered it in balsa.... D'OH!

 

[jhitesma]

On a somewhat related note. My friend who occasionally takes me up in his full scale plane sent me a PDF today about someone who used their 3D printer to make a prop for their "real" plane.

I'm not sure if I can share the PDF he sent me or not yet...waiting to hear back on that. But basically it's a CF prop and the guy used his 3D printer to print the core he used to build up the carbon fiber. So the 3D printed parts aren't structural - they're just there to act as a skeleton to support the carbon fiber layup while it cures. He did leave them in though and didn't make any attempt to remove them after the CF had cured so the 3D printed parts are still there in his actual prop that he's flying with.

My take on it was that it seemed a horribly inefficient way to do it. If he has the resources to build his own plane (it's on a kitplane) and his own prop, then why not build a CNC machine and machine the cores instead. Would take WAY less time. He quotes 6-18 hours per piece to print and he's got 5 pieces per blade on a 3 blade prop. Even at 6 hours each that's over 90 hours to print! Machine those cores out of balsa on a CNC and he'd be done in one afternoon.

Kind of like my friend building his CNC machine. He asked me if I could 3D print the plates for him...but I looked at them and the smallest one was going to be a 4 hour+ print...but a 10 minute machining job on my 3D printed CNC machine. I ended up machining all of his plates in less than half time than it would have taken to print 1. And I suspect they're stronger than the printed parts would have been.

I love my 3D printer...but it's not the best tool for every job Then again I also love my CNC but it's not the best tool either! I REALLY love having a selection of tools I built and can customize so I've ALWAYS got the right tool for the job at hand






[ Says the guy who spent more on tools than parts this weekend to fix his Truck....but that was mostly because I used it as an excuse to upgrade my torque wrench that was older than me ]