Modular F-104 70mm EDF Jet development and testing

[L Edge]

I've seen some of your work. It's really great stuff. That's a big printer you're talking about to do it all at once in 15" sections. Probably about $300 at the cheapest. But you could also print in smaller sections (up to 10") which means that what you're describing could be done on the lowest end printers. Materials wise, one roll of PLA should be plenty and goes for about $15-20

Hey, I give you a lot of credit for one of the few building EDF planes out of PLA. ? for you, How do you determine the overall weight(components as well as electronics /EDF/battery) for where to put the wing saddle to get CG right?

 

[telnar1236]

Hey, I give you a lot of credit for one of the few building EDF planes out of PLA. ? for you, How do you determine the overall weight(components as well as electronics /EDF/battery) for where to put the wing saddle to get CG right?

For off the shelf components, I just weigh them with a postage scale. For 3D printed components, Fusion 360 will give an estimate of weight and CG based on assigned materials, so I'll tend to make a material for solid PLA and then a couple materials for PLA at different infills. Then it's just a matter of taking the weighted average of the locations of the CGs of different components, or of making blocks that have the right mass in Fusion 360 for OTS parts and reading the CG location. The other thing I do is make a very big battery bay to give me as much room as possible to move the pack around. 3D printed planes are mostly empty space anyway, so it's pretty easy to make enough space that you can get the CG right. And, being perfectly honest, I sometimes mess up the way the plane balances (like with the prototype modular prop I posted about) and need to stick a ton of weight in the nose to get it to work.

The CG of just the 3D printed parts of the F-104

 

[L Edge]

For off the shelf components, I just weigh them with a postage scale. For 3D printed components, Fusion 360 will give an estimate of weight and CG based on assigned materials, so I'll tend to make a material for solid PLA and then a couple materials for PLA at different infills. Then it's just a matter of taking the weighted average of the locations of the CGs of different components, or of making blocks that have the right mass in Fusion 360 for OTS parts and reading the CG location. The other thing I do is make a very big battery bay to give me as much room as possible to move the pack around. 3D printed planes are mostly empty space anyway, so it's pretty easy to make enough space that you can get the CG right. And, being perfectly honest, I sometimes mess up the way the plane balances (like with the prototype modular prop I posted about) and need to stick a ton of weight in the nose to get it to work.

View attachment 240207
The CG of just the 3D printed parts of the F-104

Thanks, you presented a nice overall picture of 3D printing. Gone from balsa to foam to 3D PRINTING? Need to explore Fusion somewhat to decide if this is new route. Looking for stuff to print that is complicated design. Lot's of hours to learn their system commands. It's very tempting.

 

[telnar1236]

Thanks, you presented a nice overall picture of 3D printing. Gone from balsa to foam to 3D PRINTING? Need to explore Fusion somewhat to decide if this is new route. Looking for stuff to print that is complicated design. Lot's of hours to learn their system commands. It's very tempting.

I look forward to seeing what you do

 

[GH05T]

Yeah, after I recently learned modeling I think it's pretty good. Other than my mental issue with how to scale everything correctly it's a lot of fun.

Thanks, you presented a nice overall picture of 3D printing. Gone from balsa to foam to 3D PRINTING? Need to explore Fusion somewhat to decide if this is new route. Looking for stuff to print that is complicated design. Lot's of hours to learn their system commands. It's very tempting.

 

[Arsenalfan1]

Telnar1236, I tried to download the open source files for Power Broker's HMD-1 on Thinkverse but got a 404 error.

Please could you kindly provide a copy of the HMD-1 files you downloaded, if your f104 is also open source, I would appreciate if you would kindly provide the files for it as well.

 

[telnar1236]

Telnar1236, I tried to download the open source files for Power Broker's HMD-1 on Thinkverse but got a 404 error.

Please could you kindly provide a copy of the HMD-1 files you downloaded, if your f104 is also open source, I would appreciate if you would kindly provide the files for it as well.

I don't think it would really be appropriate for me to supply one of Power Broker's designs here. You will have to ask him about that issue. As far as the F-104, those files are already available in this thread a few posts back.

 

[Arsenalfan1]

The files are open source so they can be freely distributed as long as the attribution to Power_Broker is maintained, I reached out to him on the HMD-1 topic but he has not made any posts in quite a while so I am not sure if he is still reading comments.

I am quite sure that it would be completely ethical for you to make it available as long as you clearly state that Power_Broker was the creator of the files (that is how open source licenses work). If you do not wish to post it openly on the forum for everyone, you can make it available to me in a one on one conversation (I will start one now).

 

[telnar1236]

The files are open source so they can be freely distributed as long as the attribution to Power_Broker is maintained, I reached out to him on the HMD-1 topic but he has not made any posts in quite a while so I am not sure if he is still reading comments.

I am quite sure that it would be completely ethical for you to make it available as long as you clearly state that Power_Broker was the creator of the files (that is how open source licenses work). If you do not wish to post it openly on the forum for everyone, you can make it available to me in a one on one conversation (I will start one now).

I just tried the link as well but I'm getting the same error. I don't have a local copy of those files unfortunately. My model is similar in concept but pretty different in execution so I never downloaded them, sorry.

My concern was that @Power_Broker seems to have intentionally deleted those files and I didn't want to share something he had meant to take down.

 

[Arsenalfan1]

He clearly stated that all files are open source and added the remark "feel free to download them" so it is quite clear he wanted to contribute it to the community, a problem on the thingiverse site is likely to be the reason for the 404 error.

 

[telnar1236]

He clearly stated that all files are open source and added the remark "feel free to download them" so it is quite clear he wanted to contribute it to the community, a problem on the thingiverse site is likely to be the reason for the 404 error.

Again, I do not have the files and get precisely the same error you do. Regardless of my thoughts on if I should post them, I cannot.

 

[telnar1236]

While I'm working on rebuilding my F-104 for the final (hopefully) time, I have been working on the next modular plane design. This time, it's designed for FPV and should be simple to assemble and easy to fly in comparison to the F-104. It's a pretty standard configuration for this type of aircraft, built for gentle flight characteristics and good efficiency. It also gives me the opportunity to use one of my favorite airfoils, the Wortmann FX 63-100. While not really suited to aerobatics, it feels great on aircraft meant for stability and range. Another thing I'm working on for this aircraft is an internal wing structure better optimized for assembly. The wing on my earlier test airframe for a modular prop design held up fine in the air, but wasn't really suited to the harder impacts that came with landing, so I've returned to a fully modeled internal structure.

 

[telnar1236]

As I'm rebuilding the F-104, I've made a couple minor improvements. First, I redesigned the flaps (again) so that they maintain a cleaner profile with the top of the wing as they deflect. I've tried to illustrate in paint.

The other change was to finish the wing tip tanks. In general on F-104s, tip tanks improve every characteristic except for top speed, so I'm hoping to see the same for this model.

 

[telnar1236]

Here is some drone chase footage of the modular F-104 flying today in 17+ mph winds. The various changes make the pitch change with flaps much more manageable.

 

[GH05T]

This design has just caught a small interest of mine, it's a bit of a long shot but I think the body of this design could possibly be used for delta wing fighter designs, even some with canards, like some of the mirage designs, the viggen, and even the IAI kfir. I wonder if they could possibly be a future project you could try after you perfect the design

 

[telnar1236]

This design has just caught a small interest of mine, it's a bit of a long shot but I think the body of this design could possibly be used for delta wing fighter designs, even some with canards, like some of the mirage designs, the viggen, and even the IAI kfir. I wonder if they could possibly be a future project you could try after you perfect the design

The F-104 fuselage kind of looks like some delta wing fighter designs, but when you look closer, the proportions are all wrong. That said, delta winged fighters are in the future. The modular nature makes it simple for some parts of the fuselage to be switched out without needing to change everything. While the next steps are to finish up the last little bits of the F-104 and then move to a fully functional prop plane, I do plan on getting back to the MiG 21 I abandoned this past spring in a modular format (a tailed delta), and to make a Mirage III eventually.

 

[telnar1236]

A quick update on the modular plane: the F-104 is now pretty much done. I've had several successful flights but want to do a bit more testing (and hopefully get more and better video) before I release the final STLs. The weather hasn't been too cooperative recently (hence the most recent video in 17 mph winds), but a final version and build instructions should be available sooner rather than later. On top of the changes I've already mentioned, I redesigned the tail fuselage to improve the thrust line which makes the plane slightly less agile, but easier to handle on the landing approach.

As far as the modular FPV design I posted a couple months back, it's a bit of a dead end. I wasn't able to get the modular connections for the tail booms to quite work right, so I'll probably revisit the idea in a month or two.

Instead, I have decided to use the now proven ideas from the F-104 to continue with the modular jets and am working on a 4-channel jet trainer (first jet, not first plane). It's a straight wing design with an 1100mm wingspan designed to fly on the same power system as the F-104 and it makes use of the flight-proven nose and EDF fuselage sections from it. The tail fuselage is compatible too, but I have also designed a lower drag but less scale tail section that is dedicated to this design.

The plane is mostly printed/built and I hope to test it next time I test the F-104. It incorporates a lot of the learning from the earlier modular tests I did so I hope that I can get it flying without problems much faster.

You can see which parts of the plane I stole from my F-104 design since I was able to use spare parts/test prints to make them. The EDF fuselage has actually been flown three times now in the F-104.

 

[telnar1236]

Here is a slightly closer look at the second modular jet. Where the F-104 was designed to be semi-scale, the new modular jet is designed to take full advantage of the capabilities of the modular connection system.

The nose and EDF fuselage sections, as I have mentioned are from the F-104, while the core fuselage and tail fuselage are new. This will let me create multiple configurations of those fuselage sections more easily (e.g. a low wing fuselage, a mid wing fuselage, a high wing fuselage, and a delta wing fuselage, and the same for the tail section). Similarly, there will be a forward swept wing, the straight wing pictured here, a straight wing without wing fences, and an aft swept wing. And there will be various stabilizer configurations. For example, the horizontal and vertical stabilizer from the F-104 are compatible with this new plane as well.

Since the CG will need to shift forward and aft with different wing configurations, the landing gear also will need to be able to be moved. To make this possible, I designed a rail into the bottom of the fuselage with multiple mounting points for the gear.

Between the two rails, I also designed in access holes to make it easier to connect wires inside the fuselage. One of the things I learned from the F-104 was how much I relied on the holes for the retracts when connecting all the servos and running the ESC wires, so even though this new plane uses fixed gear, I wanted to keep that capability.

To help prevent tip stalls there are wing fences about 2/3 of the way out along the wing and vortex generators in front of the ailerons. Combined with the 3 degrees of wash out in the wingtip, this should give the design exceptionally gentle stall characteristics.

 

[LitterBug]

Being F104, it should be easy to turn it into a U2. :-D

 

[telnar1236]

Being F104, it should be easy to turn it into a U2. :-D

Eventually