Starting my first scratch build - the FT Flyer Swappable


Staff member
Once upon a time, not so long ago (literally just a few weeks)...

... I decided to (once again) look into building a little quadcopter to fool around when I stumbled upon videos by some crazy guys not only having fun with simple multirotors, but also with DIY planes built from stuff called foamboard. I remembered that material, since I've used it to hang pictures on the wall now and then and how impressed I was with it's strength. And damn these guys were having fun, especially when crashing their planes straight into the ground. :cool:

Slowly their enthusiasm crept into my brain and started changing everything I always thought I knew about RC flying in general - like how expensive the planes are and that they are usually done once you lose control. But even more about the square people that call themselves RC pilots on their prestigious flying fields where only members are allowed. This was different from what I expected - a lot.

I always loved planes and flying, playing with the wind (and being played with) or at least with a simulator. I decided that it was time to start (and invest) in a new hobby.

For my multirotor plans I already went out of budget and got myself a Tim Taylor style Transmitter. I decided that I needed something with at least 6 channels, better more and ended with 16 plus telemetry (I love numbers...)

  • Transmitter FrSky Taranis X9D Rev. b
  • Receiver FrSky X8R 8/16Ch with Telemetry
  • FrSky Lipo Voltage Sensor w/ S.Port
  • FrSky S.Port GPS Sensor (v2)
Fast forward to today (well thursday) when I went to a local hobbyshop and bought some additional equipment:

  • 2 x Multiplex Servo Nano-S (UNI) - 8g
  • 1 x SimProp Electronic APC Slow Fly Prop 8x4.7
  • 1 x LRP 600 mAh, 2 S, 30 C Expert Line LiPo
  • 1 x HiTEC Multiplex multi charger X1mf plus
  • 1 x Robbe Roxxy BL Control Micro 10A ESC
  • 1 x Robbe Roxxy brushless motor 2824-26, 1380 kv
  • 1 x 120 cm spring steel, 1.2 mm diameter
  • 2 x Mini pushrod connector (too small for steel diameter...)
  • 1 x Aircraft plywood, beech, 1.5 mm
While looking for foamboard I noticed that the manufacturer of the Kapa Line foamboard is located near my hometown, so I stopped there on the way to visit my family and was able to get 5 second quality boards (70 x 100 cm) for 1 Euro each. I think Kapa is heavier than the Dollar Tree foamboard (the 5 boards weigh about 2666 g) , but I have no reference, so I just have to try it. Handling seems similar: I can cut all the way through, make 50 % score cuts, "snap" the foam and remove the paper if necessary.

Working at the IT department of a university I had no problems with plotting the FT Flyer Swappable full size plans and found a lab where people allowed me to laser cut the firewall.

So I used my Saturday evening and started this:


Of course there were a few a lot of small problems like:

  • skewed cuts (looks like my free hand cuts are better than trying to push the blade along a ruler?),
  • a broken BBQ skewer just after gluing it into the front,
  • missing packing tape,
  • missing control horns,
  • soldering station in different city does not allow to solder bullet connectors
  • angled motor holder
  • mini pushrod connectors are too small for the steel rod
  • servos too big for the hole - easily fixed, of course.
  • no throw gauge

And finally I managed to glue my power pod under the inverted(!) wings while trying to give the fuselage some extra stability. This needed some chirurgical precision to "unglue"...

But problems aside - with a lot of virtual help from Josh, I managed to get to this state:


Also some questions came into my mind while building: :confused:

  • What diameter are the FT BBQ skewers? Mine seem to be a lot thinner...
  • Are plans for the control horns available?
  • Does it make a difference on what side the control horns go (paper hinge / cut side)?
  • What diameter is the gear rod?
  • Josh mentions a throw gauge, but it is not on the plan. Where do I get it?
  • Where is the CG on the FT Flyer?

Next step: Fixing the above problems and getting it into the air. ;)
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I'm a care bear...Really?
bbq skewer is just under .5cm.... my ruler does not smaller. plan for the horns are out there but you can make your own. 1.57 mm for the wire I use for all my lighter scratch builds. I like to put my controls opposite the cut side

Ron B

Posted a thousand or more times
On the plans there were 2 small circles near the power pod that marked the cg.
lg rod is about 2mm piano wire. some have used coat hanger wire.


Dedicated foam bender
Better to have the controls split so one is on one side and the other is on the other side. If memory serves, the rudder is on the left, elevator to the right. As long as your pivot is directly over the hinge line, it doesn't matter if you are on the hinge or bevel side. I have done both ways with no ill effects.


Professional noob
For a throw gauge, i just made my own. The angle you will need is about 19 degrees. For control horns, FliteTest has a video on scratch building tips that shows you how to make a control horn out of a zip tie.


Staff member
Thanks for the input guys. I love this community. It's one of the most helpful ones I've been a member of so far.

Instead of using BBQ skewers I now used a 3mm wooden rod from my hobby shop which is a lot more stable too.

I've found plans for a users version of the control horns, so I could get them laser cut from 1.5 mm wood. For a beginner like me this helps because I can adjust the throw more easily. If I use a zip tie as a replacement I have a fixed angle after gluing it in.

After cutting the foam parts I threw away the paper and went back to the trash later to check for cg markings, but somehow missed them. Perhaps I've looked on the wrong side of the paper? =)

For the landing gear I've now used 2.5 mm spring steel from the hobby shop again, which is really hard to bend and probably too heavy anyway.

Which is my next problem. After fixing some stupid mistakes and making more (like having a mounted prop when connecting the battery for the first time to a not initialized ESC) I now have a plane that looks like it might be ready to fly.

The problem, is: it weighs (without battery) 415 g with landing gear (375 g without). That is a lot more than the 225 g the "official" model weighs. The main reason being that Kapa foamboard probably is a lot heavier.

My motor / prop / battery combination delivers about 220-230 g of thrust according to the manufacturer. Will that be enough to fly?

Ah, whatever. As soon as weather and time will allow it, I will just push the throttle and see if it moves. If not, I will change stuff and learn what to modify to finally fly.

If everything fails, I can still fall back to my original multirotor plans ;)

PS: The hobby shop guys already reply with "see you tomorrow" when I tell them I really got everything this time.