My Impressions of the new electric setup !
Well, you could imagine my surprise and happiness when the Focus 2 first went up in the air. I was totally surprised by the power, smoothness and slow downline capability of the airplane. People that came along to watch me fly were amaized in general of the characteristics this plane has shown straight off the bat. So much of what I read about other peoples experiences with the Hacker / Thunderpower setup materialized in front of my eyes and I found myself agreeing with them and fell in love with my new plane. Now it came down to practice, practice and more practice. The possibility presented itself for me to go for the Canadian team. I had a lot of catching up to do.
After several weeks of practicing on the new setup I took note and realized the limitations of this particular airplane, motor, prop configuration. I also have a theory about why. First of all and almost immediately I weighed the airplane and realized I was overweight by a few ounces. So the obvious things where taken off the airplane or components were modified to save weight. Wheel pants came off, and use of super light wheels. I even trimmed excess velcro off the straps used to hold the batteries in place. The final result was a of weight something around 4.9695 KG depending on the TPbattery set I used. Now with the new lighter Thuderpower 10S 3P's the weight situation is well under control. The noise produced by the Hacker C50 gearbox seemed not to be of concern. Naturally It sounds much different than any 4 stroke of 2 stroke glow engine, its just that the frequency pitch is higher and when read by a sound meter was right on the limit. Not a good feeling but legal is legal no matter how close to the limit. As for airplane speed I initially noticed how much breaking there was in having a huge 22 inch APC prop. It was a great feeling to have those extra moments of time to line up the plane or do whatever had to be done on any given down-line leg of a maneuver. I however noticed that especially in wind, most of the throttle was needed in horizontal maneuvers or the plane did not groove properly and was unstable. Verticle performance was wonderful. Point rolls also needed a fair bit more rudder correction and more throttle than I would have liked. My theory of why this could be so is simply this. The Focus 2 is designed for a glow engine which swings a much smaller prop at higher RPM. The resulting smaller tighter volume of air pushed by the prop is concentrated much more tightly over the tail surface compared to a larger prop pushing a larger area of air not as fast. I guess that a re-design of the tail section would be in order for this configuration. Also, It seems to me that the Focus likes a bit of speed. My conclusions about speed are this. The e-version of the Focus 2 with Hacker C50 has to be flown fast. Downline segments of maneuvers can be nice and slow.
Battery flight times and charging. I spent little time in figuring out what was possible as far as how much I could push my batteries in a flight. I adopted this one way of managing battery resources on a typical preactice day. Employing 3 sets of batteries and employing 2 chargers. Fly 1rst set for 7-8 minutes, land, replace with second set, charge 1rst set for about 20 minutes while flying 2nd set. Land, change to 3rd set Fly for 7-8 minutes, land, go back to 1rst set and charge 2nd set. Land, wait about 15 minutes and fly the 2nd set. So, with 3 batteries and a bit of waiting around one is able to have 4-5 flights in an evening. As for competition, one set of batteries are good for one flight and you must re-charge for the next flight. Charging at the end of each practice day at home was a 3 hour deal. Pain in the butt.
One of the new pains about an electric setup is charging batteries. Charging is about the most time consuming boring and mentally painful chores that one has to perform and it is not so straight forward as one would imagine. The batteries that I am using are a Thunderpower Lipo 42 volt system. Two - 21 Volt battery packs are hooked up in series while in flight however they are charged separately. I have been using the Astro Chargers for Lipo batteries both at the field (charging between flights) and at home. Each battery pack after a practice session is drained (to acceptable level) and needs to be on charge in a monitored, well ventilated environment with a 12 volt power source. The draw of the two chargers going at once reads is a touch over 12 amps on the chargers but I am told recently that the draw is much more than that. That's a lot of amps! and each battery pack takes about an hour to charge up. To have a decent practice session, one must employ 3 sets of batteries, so that means a nightly charging session of about 3 hours. Not fun and very frustrating if your power source keeps dipping below the required voltage for the charger to work properly.(ie. more than 10 volts) I guess that the trick is to have a proper Deep cycle battery or batteries (Not Canadian tire crap) and a good Deep cycle battery charger, or you can put the batteries on charge on your car battery while your car is running (waste of gas and nerves) To get this charging setup going it requires money and trial and error. I returned a few defective deep cycle batteries as well as crappy chargers. I have figured out a way after re-wiring my car to charge batteries on the way to and the way from the flying field which saves time and electricity. I have run some 12 amp wire from the battery to the tail of my SUV and hook up the chargers there. So far I have blown a 12 amp fuse that was part of the circuit. I guess the chargers do draw more than 12 amps :) This means I simply have to throttle back the charge rate a bit.
At the end of the day I have a smile on my face. Airplane clean and new looking and minimal cleaning required. No servo damage or replacement / maintenance at all. A few 22 inch props chipped because of poor prop clearance. This year already I have a couple of new Gel cell deep cycle batteries ready for testing. Also I am looking forward to getting my new plan back from Jeff Stevens. He is putting together my new project. An Impact ARF. This will be flying with a Plettenberg Xtra Outrunner and the same Thundershower setup.
