Hawker Hurricane and Hawker Hunter

[Andrew Fernie]

I really wanted to spend more time flying, but until the weather dries up a bit more of my hobby time has to be indoors. So, here is some information about two planes I have been working on. Both are 3D printed, but very different designs. I printed, built and flew a Northern Pike (https://www.thingiverse.com/thing:3040294) a few years ago and it flew very nicely until it had a hard landing. It used standard PLA (the most common 3D printed material) and was a bit brittle. Eventually I will get another one built in PETG which will hopefully be a bit more forgiving.

Both of these new planes are printed from Light Weight PLA (LW-PLA). If you look at a 1kg spool of regular PLA and another 1kg spool of LW-PLA they look about the same size so it doesn't seem like the LW-PLA is really lighter. But, when it is printed at slightly higher temperatures than regular PLA it expands like a foam and you end up with roughly 1/2 the weight for the same volume. It is also more flexible than regular PLA, and sands and paints nicely. The surface finish isn't perfect (unless you want to do a lot of filling and sanding), but stand back a few feet and it looks fine.

[Andrew Fernie]

The first of these new planes is a Hawker Hurricane Mk II (https://3dlabprint.com/shop/hurricanemkii/). The download is US$20 which seems very fair to me given the effort that went into the design and preparation. 42" wingspan, retractable gear (or fixed if you prefer). It was an easy build with about a bit less than 40 prints to make for a total of about 40 hours of print time over about a week. It is designed to be produced on 3D printers with a 200mm x 200mm x 200mm build volume, so pretty much any printer. Parts are glued together with medium (or thick) CA.

I mentioned above that LW-PLA is easy to paint. I went to the dollar store and bought a bunch of 4 oz bottles of acrylic craft paint for $2 each and my wife helped me mix the colors to match a photograph. Colors were brushed on then the aircraft was sprayed with an clear acrylic satin top coat to get a consistent finish. Decals were produced by printing (standard inkjet) on self-adhesive vinyl paper and sprayed with the same clear top coat. They didn't stick to the aircraft all that well, but some 3M-77 spray adhesive fixed that.

There are two servos and two electric landing gear in the wings, so four servo leads with three channels. Space is a bit tight between the wing and fuselage so to make assembly at the field a bit easier I used an SBUS converter that allows four channels to be driven from the SBUS output from the receiver. So, only one connector to hookup. All of the FrSky receivers I have come across have an SBUS output, and I think that it was Futaba that came up with originally. Not sure what Spektrum's equivalent would be.

[Andrew Fernie]

The next one, which is a bit more ambitious is a Hawker Hunter EDF (https://cults3d.com/en/3d-model/game/hawker-hunter-f-mk-6-70mm-edf-jet). This is a free download. It only has a 37" wingspan, but is 49 inches long, and is a more complex structure overall. I have liked the Hunter aircraft for many years - I think that the proportions and lines look "right". I handled the flight controls for the simulator built by CAE in the mid-80's, and had the chance to perform some tests on a privately owned aircraft at the Mojave airport in California (see attached photo). Ground test only, but we had the engine running.

This is also printed in LW-PLA. About 40 prints with a total of about 115 hours of print time. The elapsed time in days isn't three time as long as with the Hurricane as there are some long prints (7-9 hours) which can run overnight. It needs a 210mm x 210mm x 205mm build volume, so it too should be OK on most common printers. The prints are almost finished (need to redo the canopy), and the two main fuselage sub-assemblies are done. I have a limited tolerance for CA fumes and the designer of the Hunter suggests clear Gorilla Glue so I am using that. It seems to work very well - you just need to have a bit of patience to allow it to dry rather than the instant gratification (and sneezing) you get with CA. I will use the same dollar store acrylic paint technique as I used for the Hurricane.

If you are not into building and just want to fly, 3D printed planes probably aren't for you - not nearly as rugged as other build approaches so I don't expect that the lifetime will be all that long. On the other hand they are cheap to build (assuming you already have a printer). I have used about two rolls of LW-PLA for both planes, so a total of about $100 for the two airframes. If the worst happens then back to the printer to make a replacement. Also, you can have something a little different from the others out at the field.

[briankizner]

Nice work and a very clear explanation of the process

[Tarek Hassoune]

You did a very good job Andrew nice finish. I did print a Cessna a while ago it flew very good but on landing I lost the front gear although it was a perfect and smooth landing, ever since I stoped printing planes

[Xavier]

Nice planes Andrew. My friend Leo has printed more than 40 airplanes since 2019 and I tried a few of them. In general they flew as well as any other similar planes.
The designs and the printers are way better than the first ones I have seen almost 10 years ago so the planes are better also and lighter.
Indeed there is a lot of work into designing the plane properly. Anyone just have to try doing it to realize that 20$ is actually very cheap :-)
Leo printed a Notos for me 4 years ago and the plane has more than 100 flights now. It is equiped with a motor out of a crashed Maule and 4 small Hitec servos 5055MG.
It's still fly as well as new. I used it many times to practice pattern and Imac sequences and even did one flight in a contest.
In the first few flights, I did a few adjustements and when Leo printed one for himself, he set it up the same. On the first flight, the plane was flying as well as mine. Anyone remember the last time they build 2 identical planes that flew the same on the first flight ? :D
Enjoy the flying.
Xavier

[Andrew Fernie]

100 flights! You give me hope, Xavier. Any idea of what material he used?

[Andrew Fernie]

Found the Notos (https://www.planeprint.com/notos) - combination of PLA, LW-PLA, and TPU. They have a few nice models, including a few with 70mm EDF like the one I have for the Hunter. Maybe I will give one of them a try.

[Xavier]

Indeed mostly LW-PLA. I think the PLA is from the nose to the trailing edge and the first section of the wing at the root. The TPU is probably the wheels and the hinges for the control surfaces. There is also a small o'ring on the canopy lock.