Scorpion Mk2 assembly day 8: Final steps.
This is the final stage of the Scorpion assembly.
It involves installing and drilling the wing tube, the fins, setting the batteries and installing the receiver.
My receiver choice went for the Weatronic micro 12, which I consider as being one of the best device on the market for a great price. It offer invaluable features to me like data logging and advanced flight analysis which enables me to validate the flight tests.
The switch is an Emcotec BIC v2. A nice device that works as a battery backer, voltage regulator and capacity counter. It works pretty much like a Kodiak system and is very handy for A123 elements.
It also gives indication of each battery voltage, actual used current and total capacity used. That is interesting when testing the electrical system before maiden. I have used the BIC for many years in hot/ desert conditions in Dubai and never had a problem with it.
The wing tube is very easy to install. It is just a matter of centering it in the fuselage and drilling the center through the main bulkhead to fix it. Then the wing panels just need to be assembled and the tube drilled through the pre-made hole. Really a matter of minutes.
The same process goes for the fins. It takes a little bit more time as there is no driling mark on the fuselage. You'll have to make sure that you will drill through the tube and not outside of it. The best technique I found was to use a powerful LED flash light to highlight the tube area by transparency from the inside of the fuselage. Worked out very well and it only took me a few minutes to find the drilling sweet spot. I used countersi
nk screws for the fins that come flush on the fuselage.
The batteries have to go into the nose. I used two ThunderPower 3700 mAh LiPo batteries for the receiver and one 4000 mAh LiPo battery for the engine. A typical flight burns 200 mAh so I guess that two 2000 mAh battery would be largely sufficient for a good afternoon of flights. Similarly a 2500 mAh ECu battery would be sufficient as well. With the heavier batteries I used, I have to place them as far aft in the nose section as I could. Lighter batteries could go further forward in the long aircraft nose.
The aircraft setup should be done according to the user manual. The throws are good and the only thing I did not implement was exponentials. At 155 mm, the CG is fairly fore and the model certainly feels nose heavy, but I still recommend to start with this setting to get used to its flight characteristics. It makes the Scorpion very stable and very easy to fly. Also the plane does not stall at this CG.
I went for a full battery of tests before the first flight, including fuel system test, engine test, electrical system test and range test. All was perfect and the maiden went very smooth.
The electric gear together with the VT-80 make this airplane extremely easy to setup at the field. It is just a matter of bolting the wings and filing the tank. I get the plane ready within 5 minutes after I arrive at the field and similarly the car is ready to go in 5 minutes after the last flight. Very convenient for those who have the family waiting at home!