The Nerdoligist FF20

[iceking1152]

I discovered this edf jet on YouTube when searching for F-20 Tigersharks that people had made. The channel is The Nerdoligist, I am posting the plans here with his permission - "All my IP is free as a way to give back". He generously added optional 3D print files for The canopy - both front and rear section, the nose cone, and a vent for free online here.

Build Video and testing - Nerdoligist content.

My parts list:
X Fly 64mm 12 Blades EDF Ducted Fan with 4S 2840-KV3200 - $33
Hobbywing Skywalker 80A ESC with Reverse, had to solder on XT60 - $39
5x 9g Miuzei Metal Gear Servos - 2Ail, 2Elev, 1Rud - $10
HRB 3000mAH 4s Lipo with XT60 - $30 (use between planes, but I bought it for this as it's my first 4s)
Radiomaster R88 for now, that I salvaged out of my mini sea duck as it was only using 5 channels, so it got an R86 that a local hobby store had - $20
4 Sheets of foamboard - $20
5mm square carbon fiber spar - $15
FT Landing Gear, but I use my own 3D prints - $10
Total: $177 ($147 without battery)

I wanted to share my journey building this as it is now my 3rd foam board plane, but first EDF jet to be owned and built. I have finally learned CAD enough to design parts to weigh it down with. His design is a belly lander, so I have designed landing gear adaptors somewhat based on the prints in the FT Tricycle Gear that I had bought, but made to fit around the square 5mm carbon spar that I used to reinforce the wings, with a removable bottom section that the gear attaches to. Also, I am not the first to design a 64mm EDF motor mount, but this one is mine for this application. The design for the gear is somewhat final as I have already built them into the wings, so I attached the current iteration .stl. I can still modify the lower portion, though.
This is a picture of the final iteration in HIS video:

So far I have made the wing assembly and affixed my landing gear adaptors, shown below. Everyone at my club says a trope of EDF jets is owners punch the gear through the wings, so I attached these directly to the spar. I cut out a portion all the way through the of the bottom of the wing right near the end of the foam spar on the inside before folding it to accommodate them. They have M3 threaded insert holes, which is going to be a big thing for this project as I bought a 100 pack of them and 800 pack of M3 screws. These screws hold on the bottom portion that accommodates FT Medium Landing Gear Wire which is 3/16" using the same bend around technique you'd use with their design. This way the gear is still removable, and even though the upper parts juts out below the fuselage line, I could always make a cover to put on there when the gear is not in use to replace the skid that's right next to it. I probably will do this because I need to cut that portion away anyways as I forgot to put control horns on the servos before gluing them in.

The pieces on top are the top pieces with the holes for the M3 threaded inserts. The inner holes on the bottom pieces are for the landing gear wire, and the outer, bigger holes are for M3 screws to hold these pieces on. They should slot into place with the bar/recess.

Top piece with the inserts.

Top pieces installed in the mostly-finished wing assembly. I am using a 5mm square carbon fiber spar, these top pieces have a square hole that these fit snugly on.

V1 and V2 of the 64mm EDF motor mount. V2 is close, but needs some adjusting. I am currently printing V3 that makes that thrust tube holder a separate piece, among a few other small changes. I will post the files once it's ready.

 

[Mr Man]

I discovered this edf jet on YouTube when searching for F-20 Tigersharks that people had made. The channel is The Nerdoligist, I am posting the plans here with his permission - "All my IP is free as a way to give back". He generously added optional 3D print files for The canopy - both front and rear section, the nose cone, and a vent for free online here.

Build Video and testing - Nerdoligist content.

My parts list:
X Fly 64mm 12 Blades EDF Ducted Fan with 4S 2840-KV3200 - $33
Hobbywing Skywalker 80A ESC with Reverse, had to solder on XT60 - $39
5x 9g Miuzei Metal Gear Servos - 2Ail, 2Elev, 1Rud - $10
HRB 3000mAH 4s Lipo with XT60 - $30 (use between planes, but I bought it for this as it's my first 4s)
Radiomaster R88 for now, that I salvaged out of my mini sea duck as it was only using 5 channels, so it got an R86 that a local hobby store had - $20
4 Sheets of foamboard - $20
5mm square carbon fiber spar - $15
FT Landing Gear, but I use my own 3D prints - $10
Total: $157 ($127 without battery)

I wanted to share my journey building this as it is now my 3rd foam board plane, but first EDF jet to be owned and built. I have finally learned CAD enough to design parts to weigh it down with. His design is a belly lander, so I have designed landing gear adaptors somewhat based on the prints in the FT Tricycle Gear that I had bought, but made to fit around the square 5mm carbon spar that I used to reinforce the wings, with a removable bottom section that the gear attaches to. Also, I am not the first to design a 64mm EDF motor mount, but this one is mine for this application. The design for the gear is somewhat final as I have already built them into the wings, so I attached the current iteration .stl. I can still modify the lower portion, though.
This is a picture of the final iteration in HIS video:
View attachment 256397
So far I have made the wing assembly and affixed my landing gear adaptors, shown below. Everyone at my club says a trope of EDF jets is owners punch the gear through the wings, so I attached these directly to the spar. I cut out a portion all the way through the of the bottom of the wing right near the end of the foam spar on the inside before folding it to accommodate them. They have M3 threaded insert holes, which is going to be a big thing for this project as I bought a 100 pack of them and 800 pack of M3 screws. These screws hold on the bottom portion that accommodates FT Medium Landing Gear Wire which is 3/16" using the same bend around technique you'd use with their design. This way the gear is still removable, and even though the upper parts juts out below the fuselage line, I could always make a cover to put on there when the gear is not in use to replace the skid that's right next to it. I probably will do this because I need to cut that portion away anyways as I forgot to put control horns on the servos before gluing them in.
View attachment 256398
The pieces on top are the top pieces with the holes for the M3 threaded inserts. The inner holes on the bottom pieces are for the landing gear wire, and the outer, bigger holes are for M3 screws to hold these pieces on. They should slot into place with the bar/recess.
View attachment 256399
Top piece with the inserts.
View attachment 256400
Top pieces installed in the mostly-finished wing assembly. I am using a 5mm square carbon fiber spar, these top pieces have a square hole that these fit snugly on. View attachment 256401
V1 and V2 of the 64mm EDF motor mount. V2 is close, but needs some adjusting. I am currently printing V3 that makes that thrust tube holder a separate piece, among a few other small changes. I will post the files once it's ready.

Awesome!

 

[iceking1152]

Update with progress from yesterday:

The white motor mount is V3 which works well and will be going in the bird. It requires 4 m3 threaded inserts to work (6.5mm deep holes in all). The thrust tube holder is optional since there isn’t a thrust tube on this plane stock. I am opting to put my HStab on the bottom of the fuselage instead of the top, so the next project is to make formers to replace the sections of the top of the rear fuse that I cut away and to hold the thrust tube. I will post V3 files later today.

Glued in the front fuselage. Getting F1 in place and having a tight hold was very difficult. I suggest holding it with strong tape. Use the same rolling over the edge of the table technique shown in the build video to achieve all of these curves, such as this one on the bottom of the front fuselage.

Attached “intake plenum” to the front fuse-wing assembly. I forgot to align the insert holes from the top of the front fuse piece to the bottom of the intake plenum piece, I was too focused on having other things be in place/straight and it slipped my mind when gluing the intake plenum down.
If I was to do this again, and I likely will as it’s my first EDF (future lawn dart), I would glue the top of the front fuse to the bottom of the intake plenum first before gluing that whole assembly to the wing assembly. It would be easier to achieve flush fitment between both horizontal surfaces because you’d be able to test fit and see the tabs on the top of the front fuse go into the bottom of the intake without being tucked away and hidden by the wing. Then I could just trim as necessary per usual and glue the whole thing down at once with good fitment. At least that’s the plan…
I printed a few of the vents from his link and was going to use them as cheater vents. I began cutting one out, but got cold feet and stopped. It will be good to have them to put in later if it’s starved of air.

 

[iceking1152]

I was able to get some rough test-fitting done today with a few progressions, but that’s about all I can do for now as I just realized the bullet connectors from my ESC won’t fit to those on my EDF. So I probably shouldn’t glue the rear fuse-motor mount combo in place yet, to make soldering new connectors easier. I trimmed the bottom of the Vstab to barely protrude from the bottom of the top fuselage cover, to provide room for the thrust tube. A lot of time was spent staring at the project and theory crafting, but my tangible progress for today is that I made and affixed a thrust tube, I made the “exhaust” foam board piece, and I glued the motor mount into place. I also got help from my dad with bending the landing gear wire into place, I will probably revise the design on the lower portion of that to be more aerodynamic and have more forgiving fitment tolerances on one side to necessitate less accuracy when making the wire bends.

I was able to bend the medium FT landing gear wire to shape to fit into the bottom landing gear parts decently well, but I will likely tweak the design to make the channel deeper and allow for less accurate bends.

Fitment examination with the exhaust piece to get an approximation for thrust tube length. I cut away most of the top of the rear fuse to accommodate the thrust tube. It probably doesn’t need many 3d printed formers, except for one to close it off at the end. I wanted to do this as I was mostly worried about having something to secure the vstab into, but it will probably be fine.

After gluing down the motor mount I went to go plug everything in to test thrust direction and realized the bullet connectors don’t match. Oops!

Fitment of most of the pieces clipped together, except for the rear fuse and vstab being loose.

Thrust tube is taped in place and allowed me to trim the vstab to shape. I will be able to get everything together once I can connect the EDF and ESC! Lesson learned about not testing connections when I got the items >1 week ago. My current project is to make a 3d printed fixture to allow for steering nose gear

 

[L Edge]

How long is the thrust tube?

 

[iceking1152]

How long is the thrust tube?

25.8cm length, 64mm inlet and I shot for 55mm exhaust. The 2840 motor would subtract 28mm from the exhaust diameter, I plugged in the numbers into a calculator linked on an ancient Flite Test article. It said 90% would be ~55mm exhaust diameter. The thrust tube still protrudes a bit as shown in the last pic, the foam board exhaust cover isn’t yet glued on so I can still trim both pieces as needed

 

[iceking1152]

During my first thrust test yesterday on 4s after I got the 4mm bullets soldered on, the back half of the plane flew off the desk at 1/2 throttle that I carelessly set it to right after I plugged it in.

Test fitting with the printed thrust tube. This was an easier way to control the diameter, though it isn’t easily swappable. I made up some formers for the thrust tube to be held up and the rudder to be held in place but I didn’t end up using them.

Motor mount and rear fuse and joined with the main fuselage and I was making up the nose as I was procrastinating putting on the top fuselage cover. This was as far as I got last night.

Making up the cockpit. This area was really tricky and I made janky fixes to get mine to be somewhat acceptable. The progression goes from horrifying to not bad from 10+ feet.

With the collection.

Setting up my custom steering nose gear. It’s a tight fit with my 3000mah battery, I may have to get a smaller one for the vent to not be blocked. But the cg is fine with the battery still. I was glad to be adding weight in the nose with the servo and the contraption though. The white vent is a remix I reverse engineered from the one the Nerdoligist provided. I made it shorter to accommodate the nose gear assembly. This was an excellent CAD exercise. It was supposed to interface with the nose gear assembly with and m3 and threaded insert but I broke the tab off. It will be fine without it

Sitting up on the incomplete landing gear. The nose gear has a glued in control horn, so that’s as long as it’s going to get in the nose unless I adjust it. This nose gear is completely removable, just take off the bottom collet and then you can slide it up enough to access the top collet. You’d have to take off the glued-on control horn, though.
I got it hooked up to my transmitter and couldn’t get reverse thrust to work. Maybe I had to program my ESC, but it’s too late now. Hopefully the fix is in the TX. The thrust test seems acceptable. I just need to finish up the landing gear, glue in the small vent, and make control linkages, then it’s good to maiden.

 

[iceking1152]

Attaching some of the .stl I made here. The FLGSA, or front landing gear steering assembly uses 1 servo and the medium flite test landing gear wire - 3mm. You can screw or hot glue in the servo. The top bar (dark blue) is for support but is optional, uses m3 threaded insert and screw. So does the bracket at the bottom to join it with the vent, both are optional. The nub is a spacer you can print, I have one between the fuselage and the collet on the bottom, as well as one on the top side for spacing.

Thrust tube and motor mount. The former for the rudder and the holder didn't end up making it into this bird as they needed some adjustment and I realized they were dead weight. The thrust tube holds fine with some tape. I sectioned it so it would be feasible to print, the tubes should interlock together nicely. Again, another great cad exercise for me. The thrust tube holder is attached with m3 threaded inserts and screws. The thrust tube is optional and will require modification of the rear fuse and the rudder to install.
I haven't yet changed the rear landing gear, it works fine for now.

 

[iceking1152]

Got my steering nose gear working, video here:

 

[iceking1152]

Maiden flight went super well. Takeoff was a bit sketchy as I was about to go off the runway. The ground handling is great. The air handling is also great. I don’t have much to compare it to as it is my first EDF, but it was a lot of fun. I had my timer set for 3m and landed with ~45% left in my 3000mah 4s.
The front landing gear assembly got messed up but didn’t break on my hard landing (shown below), I was able to fix it enough to be rickety but acceptable for another flight. Turns out that support that I made but left out would’ve been useful. I am going to use what I learned today about the shortcomings of this design to revise the design of the front landing gear to prioritize serviceability and durability. Right now it is not easily removable.

The control horn skipped over the support peg and got stuck on the other side. I was able to loosen the gear enough to get it back on the correct side, but the steering box lost a lot of adhesion to the fuse on the impact, so it was rickety and uneven after that.

I will be getting a scale soon to have a better idea about weights of things. This will help a lot for the V2 of this bird…

 

[LitterBug]

Nice timing with the other jet flying over. Sounded like you hit the afterburner!

 

[Mr Man]

Great job!

 

[iceking1152]

I made a custom fitted battery tray for this build and my battery in place of the vent that I did not end up using. It's a very tight fit with my 3000mah 4s and I need to have the receiver and the battery cables on top of the battery to have enough weight in the nose for the cg to balance with the marks from the plans. I am not sure what effect my mods had, likely weighted the tail end compared to stock if I had to guess, so without the motor mount and thrust tube it probably would be a bit more forgiving. This tray allows 0 adjustment, it is solely meant for this 1 battery.
I am currently working on a 3d printed front hatch section, the section that is currently poster board. This would allow me to 1. better magnetize/attach it, 2. achieve better/less ugly fitment, and 3. allow me to cut out the bottom section to open up more room in the battery compartment. This will bode well for when I get into FPV and scale this design up to 90mm EDF or something crazy when I'm a bit further along with the hobby.
The blue bar at the top of the steering gear is doing a ton to keep it laterally stable, but it blocks the servo arm a bit. It's a bit cursed/illegal but I moved the servo arm to be offset so it doesn't run into the post section of the bar.