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.

 

[iceking1152]

It's been awhile, but I have some updates regarding this project. I crashed my original version on its 4th flight way back in April, and it took up space with the nose section cut off for awhile, until I fixed it recently. In the meantime, I built a second version, but that will be detailed in a later comment, I am focusing on V1 here.
Crash diagnosis: dropping a wing on turn into final approach, causing loss of orientation.
Learnings: Don't yank elevator too hard during a banked turn to turn sharper, use rudder instead. Also, paint the plane so each part is visually distinct.

With the fuselage in remarkable shape, all electronics still working, it only made sense to cut off the afflicted nose section and graft a new one on. I opted to use the original 3d printed nosecone and canopy pieces since they were in good shape, even though the PLA nosecone directly impacted the ground.

The repair used a front fuselage section that I cut away from a scrapped build during the V2 process. I cut away the tabs on the top and bottom that normally secure it into the intake and bottom of the wing so I could slide the hidden portion of the front fuse down the hole that was exposed from cutting the nose section away. Essentially, everything forward of the wing base is a single new piece, that extends about 5 inches down into the fuselage. I cut a popsicle stick into 2 thinner sections to reinforce the seam between the 2 new and old pieces, and hot glued these to the bottom, under the battery tray.
The battery tray underwent a big re-design for the V2, but since I copied and pasted it into this airframe, known shortcomings and all just to get it flying again quicker, I'll post about it here.

Now the battery tray is longer to allow adjustability for the battery position, as well as strengthen the fuselage. It is also one piece with the front gear steering assembly, to enhance the strength of it. I repositioned the vertical post to be out of the way of the servo arm, but it ended up still in the way so I had to make some cursed angles on the pushrod and horns, which made it so it doesn't turn to the left well at all. I fixed this by manually trimming it to go left and I just held some right rudder while taxiing, takeoff and landing, to get it to go straight. Suboptimal indeed and in need of a redesign. The vertical post has 3 holes to hold some magnets for the canopy. I knocked out the rear wall of the battery tray to allow the rats nest, receiver, and battery to be pushed further aft. After some hard landings that ended up in the grass, the 3d print cracked at the base where the fillet holds the axle tube to the base. It also broke the x support away from the wall of the servo holder. I fixed this with a zip tie around the axle tube and the servo holder, and this held up super well. .stl attached for anyone interested, even though it is far from dialed in.

I found gluing the servo horn to the axle to be unreliable until I used instant cure CA. That has held super well.

The front gear suspension is awesome, it is a cheap piece off amazon. Currently unavailable but this is what it is, make sure it's the 12 volt one (joke): https://www.amazon.com/dp/B09KC7PXCM/?tag=lstir-20

Rebuilt v1 weight without battery.
The flights:
Both planes had a huge starboard roll moment. I physically trimmed it out on V1 with about 1mm deflection on both sides and this got it to fly dead on. For a plane with a grafted on nose section, I was surprised it performed as well as it did. I had to tone down AIL and ELEV rates to about 75% and expo 30% to get it smooth, I switch to this from 100% after takeoff. It rolls like a drill bit, quite axially. I could vertical loop and turn around that way easily, also vertically climb. It flies inverted decently well but I didn't try that too much.
When guessing what speeds it would get, my friends joked that I liked to land at 70mph. At first I struggled to slow it down on landing approach, but this plane glides super well and I had to learn to trust that.
As for speeds, I got 65mph into a 10mph headwind at 45* dive from ~300ft. I think it could go over 80 in other conditions and with a tailwind. During this speed testing I accidentally put a 4s battery in my rebuilt sea otter and got it to 78mph with a 15-20mph tailwind!
With my new battery tray, I was able to fit a 3300 (weight 352g) and get about 4.25mins of flight time of spirited EDF enjoyment, cells down to 3.8v.
I had 14 total flights before crashing. I lost orientation on turn into landing approach after dropping a wing, but managed to save it on the 13th flight, unlike this exact scenario which led to the original crash and it happened again on flight 14. Somehow, this crash wasn't as bad and will be fixed soon. This is how I found it before touching it. It may have flown down from a tree since I used throttle to echo locate it. It flew over an entire forest plot next to our field since I gunned it to max throttle as I regained orientation during the crash sequence.
After crashing twice with loss of orientation being a factor, it only reinforces my confidence in my choice to strictly only fly V2 once before taking it to paint.

 

[iceking1152]

V2 Build:
Just a little bit of detailing left to do. Putting the final picture at the beginning of this post.

Using updated plans by @AIRFORGE , I made a sister plane to my original F-20 using the EDF, ESC, and landing gear generously donated to me by a friend from his crashed 64mm Viper. The difference in these plans is night and day. Most notably, besides specific fixes we discussed, having each piece be distinct instead of needing to be mirrored helped reduce human error by a large margin. No discredit to the original hand-drawn plans, but Airforge knocked the digitized version out of the park.

I originally wired my nav lights into the power wires for my servos, but I noticed this to be an issue when the lone LED on the tail began to melt away the foam it was glued into. After realizing I'd need to solder resistors, or use an LED controller, I ripped apart the almost-done plane, and salvaged what I could.

After cutting away the rear fuselage and nose sections to be reused, I began again. The cut-away nose section ended up being grafted onto V1, and I made a nice new one for this V2.

Build notes:
1) In my original post, I bolded and emphasized the following:
"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".
I believe this was misguided and it is instead better to set the front fuselage into the wings, then the intake plenum on top of that assembly. I will edit the original post with a cross-out.

2) Using clamps to hold the bend of the front fuselage section while securing F0 and F1 helped immensely. I used some foam to pad the clamps so as to not make an impression in the foam.

3) Vertical stabilizer strengthening: I ran a small carbon rod all the way down the vstab. I did this by cutting a foam-depth line from the top to bottom, scoring the foam on each side with the rod, then gluing it in the channel and holding it flat while the glue dried. This gave enough strength that lateral forces on the vstab began to move the "Fuse Top" piece. I added a small bulkhead at the rear of the fuse that alleviated this, but being hot glued to a posterboard thrust tube, I'm not sure how structural this hotfix truly is.

4) Canopy fitment back to front: I like to leave a little extra posterboard hanging off the canopy pieces to be trimmed away as needed. It also helps to leave a ledge off the rear of each piece, so the front of the canopy can slot under the poster board hanging off the back of "Fuse Top Front".

5) Updated battery tray/front landing gear assembly, as well as motor mount. I made a hyper-minimalist 64mm motor mount, but I believe the design is faulty as it allows a lot of air to pass by the EDF, into the area enclosed by the exhaust, in between the thrust tube and inner wall of the rear fuse. I began to experiment with learning lofts to make a fairing at the front, but scrapped that and glued in some foam scraps to help alleviate this, but I think it may have a parachute effect?

After iterating on the battery tray from the last post, my latest design is much stronger and finally allows for the full range of steering in both directions! Unfortunately for V2, this latest iteration made it into V1 after a 2nd rebuild, but not into this V2 that this post is about. I will continue to beat on it in V1 and test for issues, but for the most part, I am happy with this iteration. I added a small slot to put a zip tie around the front section, as this helped me hotfix a prior iteration at the field to keep flying. Not that I anticipate needing it, but now affixing a zip tie in the future will be easier and more secure.

Thanks for reading! If anything in this thread helps, inspires or entertains someone, I will be happy.

 

[bisco]

wow, just beautiful. love the paint scheme!