120% FT-"Speed" Arrow

I liked the looks of the FT-Arrow from the first it was released. I've been pondering what to do with this as I have a bunch of spare parts lying around but none of the Mini size. I've also been wanting to build something that is just plain fast and this idea started to come together.

First question how can I make it from what I have around and how can I make it go fast!

I figure I need to build it around the motor. I have a 2212 2700kv motor and a couple of 1300mah 4s batteries in stock in my parts but these are quite a bit bigger and heavier than what the plans call for.

This is where I did some guessing. I decided to print the plans out at 120% size to carry the extra weight.

Here's how I print the plans oversize:

I don't have a big printer and am too cheap to pay the print shop to print them out so I print them out on 8.5 x 11 printer paper and tape them together so to if you want to print these at a larger size follow these steps

1. Download the full plans not the tiled ones
2. Only up size the plans not the first two pages which are just the instructions for the plans
   The picture below is the print settings used for this build.
3. "Pages to Print" select 3-4,
4. "Page Scaling and Handling" select Poster, Tile size 120% and click cut marks.

When you do this everything works out in proportion to the original plans. The cut outs for the A and B folds are a bit loose now that they are printed at120% the size but the foam board is not bigger. I found that I just cheated to the inside of the lines and it worked out fine. The CG marks still work were they are marked on the plans.

From this point on I cut out the DT foam board and follow the build the same as the build video. 

I did find that the motor mount on the plans was a bit too small for the larger motor even at 120% so I custom made this at about 1 3/4' square. I glued this centered on the mini power pod

My wing turned out to 35 wing span.

When I fitted all the electronics in there I found that my 1300mah fit in just right. I just got lucky here. However I couldn't put on the center cover with the bigger battery in there.

Here's how it turned out.

I covered the bottom with white packing tape to help water proof it as it is winter here and its going to get wet in the snow. I also put on some black just to help with visibility. I also put on 3 push rod supports as my wires are very thin and bend in the push direction. 

Here is a video with a bunch of low passes and speed tests. I edited this video to just show the fast passes and close up shots. The parts in the video which are sunny are a test of a 6x5.5 prop. I'm not sure if it is faster than the 4 pitch prop. With this prop I can't fly at full for long as the current is at the max for both the motor and the ESC.

I was very curious to how fast it turned out so I mounted my Quanum GPS data logger on there and took it out for another flight. The Quanum connects to the GPS and will log the max speed. I have it set up on my AUX channel and when I am ready for the speed run I turn on the switch and it logs data until I turn it back off. I took the speed readings travelling 90 deg to the wind at level flight so I believe that is fairly accurate. (Logger measures ground speed not air speed so travelling up or down wind will make the reading unacurate)

See below the max speed reached. 126.5 km/hr or 78.6 mph. Thats quite fast for a little wing.

The point of this article is to show that with a bit of adjustment you can make something work with spare parts you might have in stock. It also shows the versitility of the Flite Test designs. I think I will build a second one of these but for FPV. I will attempt to break it down into two parts to fit in a backpack. Stay tuned. 

Parts in the this build

• Banggood 2212 2700kv
• RC Timer 30Amp ESC
• 5.5 x 4 Prop and tested with a 6 x 5.5
• Hextronic 5g servos
• 2 sheets of Adams Ready Board
• OrangeRX 6 chanel RX
• 1300mah 4s battery