|Bob converted his Flyin'
King to electric power using nicads in 1999, just before lithium
batteries became popular. He thoroughly documents his conversion
"I built a Flyin' King, a high-wing trainer/utility plane from BTE late last year. I now have about 40 flights on the plane so I am posting my impressions. An e-conversion of this plane was reviewed in S&E Modeler in May 1999. I built mine with fewer mods than did the author of the S&E review. My plane came out 9 lbs 3 oxs with an Astro G-40, standard gearing, 18 Sanyo 1700s, MAS 13x10 e-prop, Jomar SM4 ESC, Stitzer Aero-Vee motor mount.
"The plane is rudder, elevator, ailerons (1 servo per wing), and flaps for a total of 5 full-size servos. The wing is 80" with a 16" chord and total surface area of 1280. The wing loading is about 17 oz/sq ft. With the 13x10 prop I have 3" prop clearance with the tail held parallel to the ground. This allows ROGs off less than ideal grass surfaces. The landing gear is wide and VERY strong with no bowing under the weight of the plane. I am using 4" lite ply wheels. The plans say you can use up to 6" wheels, but 4" seem to work fine. I elected to build it as a tail dragger and therefore purchased the optional tail wheel. It comes with a nose gear. This is probably not the best plane for a first-time project due to a more involved building process than most, however, it is by far the finest kit I have ever built. It's one of those that you open the box and marvel at the quality of the components. In my opinion, the quality justified the price for the kit and tailwheel assembly. A project like this takes me 4 months or so to build - working with quality components makes that 4 months a pleasure.
"The plane in the above setup ROGs from asphalt on 2/3 throttle in 40 feet. Flying the King is a pleasure, but here too, it is not for the first-time flyer. It is a large plane and needs aileron/rudder coordination for smooth turns. Ailerons alone don't work as well. It is also faster than what I would have expected. It tools through the sky quite briskly. Stalls are not. Nose it up into a stall and the plane will stop flying, nose down almost as if to pivot on an imaginary rod that runs through the fuse sides, and starts flying again. I remember my first flight. As can be expected, I was real nervous and had a flying partner land it. He was bringing it into a slight headwind and the speed of the plane, now about two feet above the runway, decreased to less than walking speed. The plane practically descended vertically and softly (like a helicopter) those last two feet. Talk about heart in mouth.
"My primary incentive to building the King was the flaps. I had never used flaps and wanted to give them a try. Both the flaps and ailerons are substantial (their chord is probably 3-4") and they span most of the 80". The flaps are done in a different color covering and it is impressive when they drop. They drop about 75 degrees and are effective. I have down elevator programmed in so when I drop flaps the plane does not balloon up. It is also neat to drop the flaps about 30 degrees and then takeoff. The plane takes off in a shorter distance and climbs more steeply, as would be expected. The plane will loop, with only slight nose down, quite nicely. Rolls are slow and not real pretty, but that is me as much as it is the plane.... and that's not why I bought this plane.
"My only disappointment with the flying experience was the duration of flight. With the 18 Sanyo 1700s I was getting 6 minutes motor on, then I would set up for landing. The total flight duration was about 7 minutes. I would have enough power to taxi back but that was about it. Last week I bought 20 Panasonic 3000 NiMH cells (two 10 packs, in Powertubes) from Pete Peterson of MEC. I cycled therm on my SR Smart Charger and they showed 2890 mAH. I recharged at 3 amps (took 65 minutes) and off to the field. Note, Pete says he charges the first time at 3A and all other charges at 4A and his Panasoncs have been working great after about a year. Before I went to the field I checked the draw and found it to be 45 amps... too much so I changed to a MAS E 13x8 and the amp draw was now 35... great. At the field I throttled up (after peaking) and got a 14-minute motor on flight. I was at full throttle for about one minute (for takeoff and climb) and then cruising at about 1/2 to 2/3 throttle. I flew until the batteries were spent and then floated her in. I was extremely pleased with 14 minutes motor on time. I now feel comfortable setting the timer at 10 minutes and knowing I will have time to set up and land. The batteries upon landing were warm but not even close to being hot. I would have felt comfortable re-charging after 5 minutes of cool down. That was the only flight yesterday due to time constraints but I am very encouraged with the results. Note, I did change 4 parameters in the power setup. I changed the number of cells (18 to 20), the capacity of cells (1700 to 3000), the prop (13x10 to 13x8), and the battery composition (NiCD to NiMH)."