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XF-18 Super Hornet - Twin 70mm EDF Jet - Build Pics & Plans

Mid7night

Jetman
Mentor
#1
FINALLY! I know many have been asking for these plans for a while, and now I've finally got the plans finished (enough) and enough build pics that I think it's time to release them to the wild.

First, here are the jet's specs:

Wingspan: 41"
Length: 59"
Power: Twin 70mm EDF (up to 74mm), 4S-6S
Control: All-moving Stabilators or Elevons, and (optional) ailerons

Since I've built this three different times, I'll include pictures from each build so you all have the most references possible, but please don't hesitate to ask questions about anything if you get stuck. There are a few minor differences from builds #1, #2 and #3, but they're very similar. Also attached are optional 3D-printed files that you can choose to use, or not. Pictures from each build will be in separate posts following this one.

I've always loved the Hornet, and the added angles of the Super Hornet make it that much sexier to me, so I knew I had to design one. I'm just sorry I've taken so long to let these plans out.

NOTE: No, this is not a "competing" build to John Overstreet's "BDF" powered version, and this one will not likely be an FT kit. Overstreet's design (along with his F-16 and others) will hopefully soon be official Flite Test Speed Build Kits, and I can't wait to build and fly one myself! But those are aimed at a totally different flying experience, and this one is a pure-power EDF build.

For the latest build, I need to give major thanks to all the people who donated to my crowd-fund "ask for help", but I'll talk more about that build in another post later on.

And now, on to the build!

P.S. Here are links to the landing gear I used on the Blue Angel's build:
Nose Gear: https://www.motionrc.com/products/freewing-90mm-edf-f-a-18c-hornet-nose-landing-gear
Main Gear: https://www.motionrc.com/products/freewing-90mm-edf-f-a-18c-hornet-main-landing-gear-right https://www.motionrc.com/products/freewing-90mm-edf-f-a-18c-hornet-main-landing-gear-left
 

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Mid7night

Jetman
Mentor
#2
Pics from Build #1

First (and last) flight of build #1 :D
 

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Mid7night

Jetman
Mentor
#3
Pics from build #2

Flight of build #2.5
 

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Mid7night

Jetman
Mentor
#4
Pics from build #3
 

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Mid7night

Jetman
Mentor
#5
Pics from build #3 part 2
 

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Mid7night

Jetman
Mentor
#11
Do you design on Inkscape and needle cut it out, or is it freehand cutting
I design in a program called MOI3D, and export DXFs and PDFs for either hand-cutting (PDFs), or sometimes I have a friend with a laser-cutter cut them from DXFs for me. The first one was hand cut (I think), and the rest were lasered by my buddy Stu. I still hand cut a lot though.
 

BATTLEAXE

Well-known member
#12
I design in a program called MOI3D, and export DXFs and PDFs for either hand-cutting (PDFs), or sometimes I have a friend with a laser-cutter cut them from DXFs for me. The first one was hand cut (I think), and the rest were lasered by my buddy Stu. I still hand cut a lot though.
I noticed that you have intricate spar designs in your wings which would be hard to shape given the curve of the airfoil. I figured you would have to have it done in some kind of program and not just a trial and error fit process like I am used to lol
 

Mid7night

Jetman
Mentor
#14
I noticed that you have intricate spar designs in your wings which would be hard to shape given the curve of the airfoil. I figured you would have to have it done in some kind of program and not just a trial and error fit process like I am used to lol
The actual foam spars aren't that complicated, they follow the folds in the upper surface. In the most recent build, the Blue Angels one, I added several cross members through the foam spars because that plane is going to be heavier and I wanted the wing to be stronger. Those CF tube spars were actually added on-the-fly, not designed in.
 

wilmracer

I build things that fly (sometimes)
Mentor
#16
So I wanted to chime in with another build of this awesome design! I've been following along with the build and I'm getting pretty close to having this one ready for maiden. I had several jets sitting in various stages of broken and when I got my hands on this design I decided to consolidate all those parts into one!

Ben's pictures and details show the build process really clearly. I did a few things a bit differently, but not because of any design flaw on Ben's part. I don't build with DTFB, so the foam I have doesn't have paper on it. What I do is use 3m77 on the plans, cut the parts, score and prep them, and then use 3M 90 and a covering iron to attach monokote to the exterior of the part. Then I can either pull the paper from the plans to save weight or leave it if I think a bit more strength is required. The result is I don't have to paint the finished plane and I've found that, at least in the region I live in, Monokote covered FB planes last longer than even the waterproof FB.

Since I'm not working with DTFB I do a few other tweaks as well. I balsa line leading edges for all surfaces (wings, horizontal and vertical stabs, and also ailerons/elevators). For the stabs I use 2 full layers of foam and then feather sand the trailing edge. When gluing the two halves I run a strip of 1/64th birch ply down the trailing edge and then sand to that. This lets you sand your trailing edge MUCH sharper than just FB and the edge will hold up much longer. Unlike Ben's original design, I'm not using full flying stabilators (elevons?). I've been flying a similarly sized F-18 for many years and it uses fixed stabs and elevators, so I opted to go that route. A bit simpler. It won't give me the low speed handling that Ben's will have, but I tend to fly jets fast and forget to slow down until I'm out of juice.

I did also add a bit of CF in the wings for some additional stiffness. I expect this should be a pretty quick plane. I'm running a pair of Dr. Mad Thrust 10 blade Alloy EDFs w. 3000kv motors on 4s, good for about 1350W each. I tried to run these in an SU-37 at FF last year on a HUGE 4S 10000mAh pack, but the total watts melted the XT90 and shorted the leads, puffing the pack in a pretty spectacular fashion. On this build I'm using separate packs, 4S 3000 or 4S 4000 mAh, each w/ 85 Amp ESCs and XT90 connectors. One pack runs the BEC for the receiver and servos and the other pack runs a separate BEC, set to 12V, that powers the afterburner LEDs.

Graphics are from Callie graphics. They did require a bit of modification and I'm still working on it, but so far so good!
 

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The Hangar

Well-known member
#19
Man, this is BEAUTIFUL! I would really love to build one but the edf's I was looking at were $40 a piece, and then I'd need to buy some 80 amp esc's which are another $40 a piece, and that doesn't include a 5000 mah 4s pack which would probably be another at least $50, probably more like $80. So unfortunatly this project is out of my budget at the moment, but I have the F-16 plans printed off and the batteries for that so all I need is one EDF and one ESC!
 

wilmracer

I build things that fly (sometimes)
Mentor
#20
I don't remember exactly, but I think it was around 5lbs. Carl's should be much closer to that build, maybe he can chime in with what his weighs.
Mine is currently weighing in at 5lb 2oz WITHOUT batteries. There will be a bit more weight, but not much. With 2 4s 3000 mAh packs the CG is close and she weighs in at 6lb 14oz. I expect 7lbs AUW.

That is in the ballpark of the Freewing 90mm F-18, maybe a touch lighter, and roughly the same size. With the EDFs I've got I'm looking at about 385 W per lb, which is a LOT. :eek::eek:

The model could be built a fair bit lighter. Leave off the LED Afterburners, use a different power system (go higher voltage and single battery, or maybe even use BDFs). Then don't bother with the balsa lined leading/trailing edges. Leave off the flaps, and maybe even the ailerons if you're going to do full flying stabilators. Use a smaller BEC (or use the BEC from one of your ESCs). This model has 2 Castle Creation 20amp BECs (1 for LEDs, 1 for flight). If you drop all that you can use a smaller receiver as well. I've got an 8 channel spektrum w/ telemetry and a satellite module.

I have no doubt this could be built for fun well under 6lbs. MAYBE even less with BDFs.

I'm hoping this one flies like a jet and gives some respectable triple-digit passes. And hopefully lasts for several seasons.