3D/Foamboard High Performance F-16 Discussion and Design

[Houndpup Rc]

Hey guys! So I have started a new project that I expect will take a LONG time to design.....I want to design a high performance F-16 64mm EDF jet...For a while I was thinking that I would do it master series style, but I have been thinking about it and to get smooth enough ducts I think that 3D printing the fuselage will be my best bet (Not to mention it will look the most cool!) I am still on the fence as to whether wings made from foamboard would be better or not....

I do not currently have a 3D printer but I am hoping to get one this fall, so I figured that this would be a good time to start designing!

I am hoping that this thing will do 100mph+ so I think dual EDF is my best bet....Do you guys think that 100+ is too much to hope? Any suggestions welcome! @telnar1236 @Mr Man @Mid7night @CrshNBrn @Patriot Rc @LitterBug @L Edge @Proptastic @AIRFORGE @Flying Cherokee @Flying Monkey fab

-Pup

 

[Houndpup Rc]

I hope to have it build like this one in this video:

 

[telnar1236]

With a powerful 64mm fan, 100+ mph is pretty doable, though I think most 64mm jets are more in the 80-mph range. I'm curious about the method of packaging of a dual EDF in an F-16 airframe, though if you don't mind some creative liberties with the design you could do a twin engine F-16.

 

[Houndpup Rc]

With a powerful 64mm fan, 100+ mph is pretty doable, though I think most 64mm jets are more in the 80-mph range. I'm curious about the method of packaging of a dual EDF in an F-16 airframe, though if you don't mind some creative liberties with the design you could do a twin engine F-16.

Yeah, I gotta figure that out as well as keep the wing span around 30"

 

[Houndpup Rc]

I am going to keep each part small enough to fit on a 200x200x200m workspace as I believe that is the common size for most consumer printer nowadays.

 

[Flying Monkey fab]

opinion // I love my 3d printer and will have two soon but I have yet to find a LW PLA that makes major components of acceptable weight. Great for bits and bobs but not for wings and fuselage. //

Not trying to discourage you , just buffer your expectations.

 

[Houndpup Rc]

opinion // I love my 3d printer and will have two soon but I have yet to find a LW PLA that makes major components of acceptable weight. Great for bits and bobs but not for wings and fuselage. //

Not trying to discourage you , just buffer your expectations.

It seems to have worked well for @telnar1236 that guy in the video...The key is how you make the internal structure it sounds like.

 

[telnar1236]

I think that there are two big advantages to 3D printing. The big one is reproducibility. If you crash a foam board plane, you have to rebuild it or repair it, where with a 3D printed plane, you hit the button and a couple days later you have a whole new airframe with a minimum work on your part. It lets you do more stupid stuff with your planes with less fear of crashing, because it's cheap, both in money and time.
The other thing it gives you is much greater precision than can be achieved with foam. This means you can get more lift, more reliably, from a given wing area. It doesn't fully offset the higher weight, but it helps more than you might expect. It also should make it possible to build much lower drag designs than with foam board.
In terms of weight, like Houndpup Rc said, it's mostly a matter of always designing in less structure than you think you need. Small 3D printed designs will always be less durable than foam, but with LW-PLA and a vase mode structure, they can be just as light, and due to the higher lift available, some of the designs, especially from Eclipson, can pair amazing aerodynamics with very low weight and be very floaty. My own designs use ABS which doesn't do as well in smaller airframes, but once you get up above around 45" or 50", you actually start to get that weight back, and once you get up to around 60" or 70", an ABS airframe is actually lighter than a comparable foam airframe since it gives you the ability to control the structure with much greater precision.

 

[Houndpup Rc]

I think that there are two big advantages to 3D printing. The big one is reproducibility. If you crash a foam board plane, you have to rebuild it or repair it, where with a 3D printed plane, you hit the button and a couple days later you have a whole new airframe with a minimum work on your part. It lets you do more stupid stuff with your planes with less fear of crashing, because it's cheap, both in money and time.
The other thing it gives you is much greater precision than can be achieved with foam. This means you can get more lift, more reliably, from a given wing area. It doesn't fully offset the higher weight, but it helps more than you might expect. It also should make it possible to build much lower drag designs than with foam board.
In terms of weight, like Houndpup Rc said, it's mostly a matter of always designing in less structure than you think you need. Small 3D printed designs will always be less durable than foam, but with LW-PLA and a vase mode structure, they can be just as light, and due to the higher lift available, some of the designs, especially from Eclipson, can pair amazing aerodynamics with very low weight and be very floaty. My own designs use ABS which doesn't do as well in smaller airframes, but once you get up above around 45" or 50", you actually start to get that weight back, and once you get up to around 60" or 70", an ABS airframe is actually lighter than a comparable foam airframe since it gives you the ability to control the structure with much greater precision.

I suppose though, because of the control of greater precision that you should be more scientific on how you make your airfoils ect....(AKA. Don't just eye it up and call it good....)

 

[Houndpup Rc]

Got something going!

 

[Houndpup Rc]

Decided to redo it.....

 

[Houndpup Rc]

And the result is:

 

[Houndpup Rc]

What do you think @telnar1236?

 

[Houndpup Rc]

There! I think I got the nose done!

 

[Mr Man]

There! I think I got the nose done!
View attachment 253479

Cool!

 

[Proptastic]

Hey guys! So I have started a new project that I expect will take a LONG time to design.....I want to design a high performance F-16 64mm EDF jet...For a while I was thinking that I would do it master series style, but I have been thinking about it and to get smooth enough ducts I think that 3D printing the fuselage will be my best bet (Not to mention it will look the most cool!) I am still on the fence as to whether wings made from foamboard would be better or not....

I do not currently have a 3D printer but I am hoping to get one this fall, so I figured that this would be a good time to start designing!

I am hoping that this thing will do 100mph+ so I think dual EDF is my best bet....Do you guys think that 100+ is too much to hope? Any suggestions welcome! @telnar1236 @Mr Man @Mid7night @CrshNBrn @Patriot Rc @LitterBug @L Edge @Proptastic @AIRFORGE @Flying Cherokee @Flying Monkey fab

-Pup

One good project leads to another, and I love an F-16. I'll be watching.

 

[telnar1236]

What do you think @telnar1236?
View attachment 253477

It looks good. A couple of important things to consider are printability and weight. A good rule is to limit overhangs greater than 45 degrees as much as possible. You also need to consider the cooling time for each layer. Very thin towers like the Pitot tube will struggle with cooling, so it may be worth printing it separately horizontally and then inserting it. The picture in black is what I'm thinking it looks like right now, where the picture in red might be more printable and lighter. For wings and tails, you can frequently just use 3-5% infill and a single wall, or 2 for LW-PLA, and not model the internal structure, but for the fuselage this tends to end up quite heavy.

The other thing to consider is wall thickness and structure. You only want a single 0.4 mm perimeter as your entire skin. It may already be that thin, but I can't tell from the picture. Adding 0.8mm thick longerons in as part of the skin also increases strength and helps reduce warping.

This is what the nose cone looks like in my jet trainer, so not all that different, but with changes like those I'm mentioning.

Finally, you may have already done this, but it may be worth putting models of the various parts you'll be using where they should go in your model from very early on in CAD. It's very easy to design a great plane and then realize your electronics don't quite fit.

The other possible approach is the vase mode approach like what Eclipson uses. There are some tutorials online for it, but as a whole, it's harder to model but prints better. I don't use it very much, but it's definitely a good method.

 

[Houndpup Rc]

It looks good. A couple of important things to consider are printability and weight.

So I did a mass calculation in FreeCAD and then I stick the numbers into ChatGPT and it calculated: PLA ≈ 1.25 g/cm³ = 0.00125 g/mm³ giving me a approx weight of 35g for that nose cone....

 

[Houndpup Rc]

Very thin towers like the Pitot tube will struggle with cooling, so it may be worth printing it separately horizontally and then inserting it.

Yeah, I had this as a separate piece that will insert into the nose cone (There is a second former back in there)

 

[Houndpup Rc]

The picture in black is what I'm thinking it looks like right now, where the picture in red might be more printable and lighter.

So this is what I have currently: