1About flying it
At his wheel size and weight it will probably not take off on grass, as you can see in the video. You will need to take off on smooth asphalt or concrete. The asphalt I have access to here (video) is very stony and rough. So maybe a countryside good road, an empty parking lot, a field alley, etc, would do. Depending on several factors like elevation, final weight of your build, battery voltage, propeller pitch and motor, you might find that you need a longer runaway than expected. Mine in the video was about 15m and I felt like it was short like crazy. Always remember that this plane was meant to be a speed fighter in real life. So it’s small wing surface and incidence angle must be compensated with speed in order to keep it in the air.
This is definitely not a model to try if you are a beginner. Being a low winger and a speed plane it might require very quick reflexes in tight spaces and a lot of experience in this domain. Depending on the configuration, I expect that it can reach speeds of almost 10km/h. It’s over 1Kg of bullet. So this is no toy. Hitting somebody with this plane can cause severe injuries or even death. The creator of this thing (AKA ME) does not assume responsibility for any inconvenience, incident, property damage or casualty generated by improper use of this thing.
3How to build it
If you want to build this for yourself and wonder where I buy the servos, electronics and heat shrink film from, here's the link:
https://www.youtube.com/watch?v=X6wb0cdJtoM Watch the video first as I show how I welded the parts together. Yes you can heat and shrink the film on the plane without melting or deforming the PLA printed parts. No special coating required on the plastic parts. I got used to using my regular cloth iron set between ** and *** to glue and shrink the film. Some parts were left unperforated just as solid blocks. They can be printed better as hollow shells with 0% infill and they require trimming of some faces. I will add both the perforated and unperforated stls and you can decide which one to print depending on how much post printing processing you want to do. Check the printing instructions for more details.
4General printing instructions and guidelines
These are some guidelines derived from my printing experience and they could require readjusting according to your machine type and 3D printing techniques you use. I know people started experimenting with tilted prints to increase the strength and surface quality but I won’t be mentioning these things here. The instructions I’m giving here are more like what I used to achieve the product. So feel free to adopt and adapt.
For all the parts use Cura Creawsome Mod if you have a FDM printer. It seems to be fusing the filaments better and it has ironing functions on almost every layer. This results in compact prints. I tried other slicers and I even increased the extrusion factor, but only Cura gave me the necessary strength at the painful cost of increasing the printing time twice. I sliced the wheel lids with Slic3r and they ended up delaminating and breaking because of vibrations during a takeoff, as you see in the video.
Print all the parts at 0.1 to 0.2mm resolution. I printed all of them at 0.2mm layer height. It’s recommended to increase the printing temperature with up to 5% of your regular one for that specific type of filament you use. This could create oozing but the structures would end up more compact. I used 210⁰C for black and blue PLA.
Fuselage A section: The solid block one 4 shells, 6 top and bottom layers Trim the window section and the flat base with the soldering iron after printing. The perforated one Trim the window inner walls and make a hole into the flat base after printing to make it more lightweight.
Fuselage B,C,D sections Use support materials and print as they are. Aligning the fibres horizontally will give the parts the needed torsion strength. I used the line support pattern from Cura which comes off easily. I had almost no infill. I matched up the number of the shells with the number of top/bottom layers so I would get a pretty much solid print. Next time I would try to use only 3 shells and up to 4 top/bottom layers to make them lighter and use less material on them.
Fuselage E,F sections Reorientate the F piece nose down. I think I uploaded it nose up. So flat base down because this flat base will be the motor attachment plate and it needs to be compact. Be careful. Use at least 20 bottom layers for this F section so the motor will not be attached on a thin paper like shell. Print the E section as it is and don’t rotate. I printed both of these sections with no supports.
Cowl The long one looks better on the plane and fits nicer with the F section of the fuselage. I uploaded the short one too so you could install the one that fits better according to the size of your motor. Both of them prints with no supports, nose down. I think I uploaded the short one nose up so you will need to rotate it. If you decide to go with the short cowl, you would probably need to make the flat motor mounting plate of the F section less sharp around the edges. I had to fillet these edges with about 5mm to make the short cowl fit properly.
Exhaust arrays 2 to 3 shells 10% infill Attach permanently to the cowl using glue or spot welded with the soldering iron. I heated them up a little bit with the heatgun before gluing to the plane just to give them a curled shape that would follow the line of the fuselage better. I used 4 screws (2.5X8) to attach the cowl to the fuselage as you can see in the pictures.
Wings and middle section I generated the line support using Cura and I aligned the lines with the wing ribs. Check the last picture in the list for example
Cockpit Print using line support material. 2 shells, 4 top layers 0% infill trim the flat base after printing
I tried multiple string types to actuate the gear set but the best one proved to be some 1Kg fishing line as you can see in the image above. The springs are not helical ones but compression ones. I was having a pile of dismantled ones in my shop so I had to choose from different strengths and diameters. they are bout 6mm in diameter as the bolt is an M4.
The springs must have enough force to keep the lids opened and the gear down. The actuator and the string pulls the wheels closed. If the string breaks for some reasons after some hundred closing cycles, the wheel would then just fall open and the user would be able to land.
6How I painted it
I used some stencils printed on A4 paper to copy the letters and the flags to painter's tape. Then I took the painter's tape and attached it to the plane like in the picture below to create a mask for the paint. I then spray painted on top of it using spray cans.