F-106 3D Printed Jet

[telnar1236]

While I was working on the more detailed little bits remaining in the big F-106, I had an idea for what I could do with the smaller F-106 which doesn't quite have enough lift since I have a whole fuselage already printed and ready to go.

This is definitely a bit down the road if I get to it at all, but, on paper at least, the forward swept wings should give it a comparable stall speed to the big version, and a huge boost in high angle of attack performance too. The cost is that it will probably be slower and more sensitive to CG which means it won't be as good at carrying payloads like FPV equipment or anything I put in the payload bay.

It looks like the higher aspect ratio wing gets a much higher lift slope while the forward sweep keeps it from stalling till it hits an absurdly high AOA. The section of the wing left over from the delta also still generates a leading edge vortex which also helps improve the performance at high angles of attack.

 

[Mutley]

That wing fence idea is bloody brilliant. I am having a brain fart, did a version of the F-106 have a "coke bottle" shape that allowed less span-wise lift distribution? I may be butchering the theory... "area rule" I may be thinking...

 

[telnar1236]

That wing fence idea is bloody brilliant. I am having a brain fart, did a version of the F-106 have a "coke bottle" shape that allowed less span-wise lift distribution? I may be butchering the theory... "area rule" I may be thinking...

Thanks, I'm surprised we don't see something like them on some fun-scale designs since they seem like they should be pretty effective. Maybe they just look too funny or maybe there's a drawback to them I missed.
The real F-106 definitely had an area ruled fuselage, and the larger version of the model also has one. The wing should be further forwards to match up with the area ruling, but I accidentally put the wing too far back early on in the CAD and by the time I realized it, I was far enough along not to want to go back in and fix it.

But unfortunately that's mostly for reducing transonic drag in the real things. I've seen some things suggesting it might help reduce flow separation at lower speeds and reduce drag, but mostly at this scale it's just aesthetic. The real plane also had small conventional wing fences to reduce the spanwise flow, which might be what you're thinking of. I've also modeled them in the 80mm version, but from the CFD they don't really seem to have much impact at this scale. Certainly nothing like the apex fences I was looking at earlier in this thread, so they're mostly aesthetic too.

 

[JetCrafts]

While I was working on the more detailed little bits remaining in the big F-106, I had an idea for what I could do with the smaller F-106 which doesn't quite have enough lift since I have a whole fuselage already printed and ready to go.
View attachment 247872
This is definitely a bit down the road if I get to it at all, but, on paper at least, the forward swept wings should give it a comparable stall speed to the big version, and a huge boost in high angle of attack performance too. The cost is that it will probably be slower and more sensitive to CG which means it won't be as good at carrying payloads like FPV equipment or anything I put in the payload bay.
View attachment 247873
It looks like the higher aspect ratio wing gets a much higher lift slope while the forward sweep keeps it from stalling till it hits an absurdly high AOA. The section of the wing left over from the delta also still generates a leading edge vortex which also helps improve the performance at high angles of attack.
View attachment 247875

yooooooooooooooooooooooooo

 

[telnar1236]

This past week I got sucked down the rabbit hole of figuring out how to 3D print the wings in ABS. I was looking at the plane's design and realized that it was almost entirely ABS anyways so I wondered if I could get it that little bit remaining. It gets pretty hot here in the summer, so having a fully ABS plane would give me more flexibility to leave the plane in the car for a few minutes and not need to worry about it warping. It would also save about 150-200g of weight since ABS is less dense than PLA which is always a positive. And I think I pulled it off - I have a fully ABS wing that didn't warp coming off the print bed so I'm happy.
In terms of progress towards the first flight, all that remains is the design of the landing gear and landing gear bays, and then the plane will be ready to fly.

 

[Houndpup Rc]

This past week I got sucked down the rabbit hole of figuring out how to 3D print the wings in ABS. I was looking at the plane's design and realized that it was almost entirely ABS anyways so I wondered if I could get it that little bit remaining. It gets pretty hot here in the summer, so having a fully ABS plane would give me more flexibility to leave the plane in the car for a few minutes and not need to worry about it warping. It would also save about 150-200g of weight since ABS is less dense than PLA which is always a positive. And I think I pulled it off - I have a fully ABS wing that didn't warp coming off the print bed so I'm happy.
In terms of progress towards the first flight, all that remains is the design of the landing gear and landing gear bays, and then the plane will be ready to fly.

Are you going to get a video?

 

[telnar1236]

Are you going to get a video?

That's the plan. It's not quite to the point of being ready to fly yet, but you can see a video of the 70mm version in post 10. The hope is that the 80mm will fly about the same, just with a lower stall speed.

 

[telnar1236]

I ran into a bit of trouble with the design of the main gear. I forgot to account for how thick the 64mm Dubro wheels I had selected are. So, when I tried to design the gear, any possible design had the wheels sticking out the bottom. I spent quite a while trying to figure out how to fit them with options ranging from redesigning the fuselage to trying to switch to 50mm wheels, but any of the options I could come up would have compromised the fuselage structure or required me to have a 3mm pin for the wheel on this 5'10" long airplane which would have been too weak. Therefore, I've decided to design and print my own wheels. I'm a bit worried about the ability of the wheels to grip the runway, but this is the only option I can think of that will let the wheels fit in the plane.

The wheels and gear struts look extremely thin from the front, but that's mostly because of how big the F-106 is - the gear struts are similar in thickness to the F-104.

The very restricted space available results in a somewhat strange shape for the gear, so I'll see how well it holds up. There's a decent chance something will break, but that's what testing is all about

And, fortunately, it actually fits in the space available so I will have some form of gear, at least.

However, if this gear works, it will mean this plane has fully 3D printed struts and wheels with working suspension using a rubber band spring which is something I've been meaning to design for some time.

 

[telnar1236]

With a test print of one of the gear struts in hand, I'm feeling a lot more confident. The strut feels strong and can easily push down on a scale with the kind of force I expect it to see in operation.

Most critically, it fits into the printed wing as neatly as it does into the wing in the CAD model.

 

[Houndpup Rc]

With a test print of one of the gear struts in hand, I'm feeling a lot more confident. The strut feels strong and can easily push down on a scale with the kind of force I expect it to see in operation.
View attachment 248314
Most critically, it fits into the printed wing as neatly as it does into the wing in the CAD model.
View attachment 248315

What CAD do you use?

 

[telnar1236]

What CAD do you use?

Fusion 360. It's free for hobbyists and I like the workflow. But pretty much any full-featured CAD will allow the same things and it's pretty much a toss-up on which one is best.

 

[Houndpup Rc]

Fusion 360. It's free for hobbyists and I like the workflow. But pretty much any full-featured CAD will allow the same things and it's pretty much a toss-up on which one is best.

Oh....I was just wondering if you used FreeCAD

 

[Mr Man]

I too use fusion if I’m going to 3d pri t something, but for foam planes, onshape.

 

[telnar1236]

Oh....I was just wondering if you used FreeCAD

I have used it, but Freecad is much harder to use than most other software and even if you know what you're doing it takes twice as long to do anything. Fusion 360 is a much better optimized piece of software and both are free, so I use Freecad very rarely

 

[Houndpup Rc]

I have used it, but Freecad is much harder to use than most other software and even if you know what you're doing it takes twice as long to do anything. Fusion 360 is a much better optimized piece of software and both are free, so I use Freecad very rarely

Okay, I think I will look into Fusion 360 and see if it will work on Linux Mint.

 

[Houndpup Rc]

Hey @Mr Man it looks like onshape works on linux, how is it for 3D designing?

 

[Mr Man]

Hey @Mr Man it looks like onshape works on linux, how is it for 3D designing?

I like it, interface is pretty easy to get used too. And it has lots of tools.

 

[Mr Man]

RcTestFlight on Youtube uses it quite a bit.

 

[Flying Cherokee]

RcTestFlight on Youtube uses it quite a bit.

Indeed.

 

[Houndpup Rc]

I like it, interface is pretty easy to get used too. And it has lots of tools.

I think I will give it a try. can you do 2D in it too?