Andy Borgogna’s All American Sr. converted for electric flight (above). Note the cooling air intake on the model’s hatch. Cooling is essential on the electric components. The flight battery as well as the electric components are easily accessible thanks to the removable hatch (at right).
“After spending a lot of time speaking with electronic engineers and other techni- cal experts, I was able to get a decent grounding (no pun intended) in what made electric powered control line work. Now it was on to the field testing process which in- volved creating systems (motor, controller, timer, and battery). Most of these worked to a greater or lesser extent, but they were all relatively costly since controllers, batteries, and a decent charger were all priced over $100 each. Sure I could equate the charger and batteries to the cost of fuel and tell my- self that all I was doing was buying my fuel in bulk. That allowed me to tell myself that each flight was actually equal to or cheaper than a similar flight with my OS Max FP. “So what? I still could not get that perfect flight every time and when I did, it still was a constant speed without the 4-2-4 break or the tuned pipe effect I was used to. That is why I kept looking at new products and new techniques.
“While I was spending time doing this a couple of nice things happened. First batter- ies came down in price and got lighter in weight. This meant that the battery that used to cost me $150 now cost under $100. That was good as it not only drove my cost per flight down, but it made the initial up front layout of cash much easier to swallow. I could now use a less powerful motor due to the low- er weight it had to pull through the air. A less powerful motor usually equates to a lower cost. This was all very nice, but I still had that constant speed flight with no 4-2-4 or tuned pipe action. Hey, 4.8 second lap times are fine, but the maneuvers sure come up fast! “All of a sudden I was told about this fel- low in South Africa who had come up with a timer that could actually read the speed of the prop shaft as it rotated and could control the rpm all by itself. That really got my in-
Air exits top and bottom
Bolts through plywood into motor
Air intakes Air intake
terest, so I contacted him. After conversing with Keith Renecle, I decided to get a couple of his timers just to see if they really worked. Talk about a pleasant surprise! Not only did these timers work, but they solved a lot of the problems I was experiencing with my field test electric power systems. “In the first place as soon as the timer sensed that the prop had stopped rotating, it instantly shut the system down. Hey, a prop strike on a takeoff had stopped my prop and before I could get to the model and shut off the switch, the power surges had cooked a $600 system. This was never going to hap- pen again! In the second place the Renecle (KR Governor) timer took over the control- ling of the rpm. That meant that I could set my initial rpm with a tach and know that it would run at that speed every single time. No more worry about getting the perfect nee- dle setting for my second official flight in the afternoon!
“Also of great importance was the fact that since the timer controlled the rpm, I no longer required a very expensive electronic speed controller. This drove my costs down by at least $40 per power system. But the third thing about this new timer was that somehow Keith Renecle had figured out how to create the perfect 4-2-4 break or to be more accurate, an electronic tuned pipe ef- fect. Now my system would give me 5.4 sec- ond lap times and automatically increase power when I hit the maneuver. Hey, now I had a system that worked just like the old 4- 2-4 and newer tuned pipe power systems that I was comfortable with.
“What I now had was a fully field tested power system that worked every time I flipped the switch. I now had the OS Max FP in an electric powered control line system. Not only that but the initial cost to acquire the system was just about equal to what I
would have to spend on a decent contest tuned glow engine.
“To sum things up here is what we have. 1) Initial cost for the system equal to a de- cent competition level glow engine.
2) A perfect motor run every time I flip the switch.
3) The ability to change my rpm, flight length, or power boost with the press of a button (no laptop computer needed).
4) Instant safety shut down in the event of a prop strike.
5) A flight that is similar to what I have come to expect from a really great glow engine run.
6) No more need to fuel proof everything. 7) The ability to fly almost anywhere without getting hassled about engine noise.
“I don’t know about you but this sounds
really good to me. Of course I still do not hear that engine sound. Maybe I’ll have to come up with something that can hold a playing card on the fuselage side so that it hits the back of the prop (something like I used to do with my bicycle back in the day to make that engine sound).
“In all seriousness, give electric a thought or two. Maybe you, like me, will find reasons that gives it a place in your future power sys- tems. If not, don’t worry about it at all. Glow engines are not dead in spite of what some of the prophets have been saying. When you get right down to real facts and take all of the garbage out of it, electric power systems are just a different way of making the plane go through the air. I still see Fox .35, ST 60, and tuned pipe powered models win contests and am likely to do so for the rest of my life. Now I am probably going to see more electric pow- ered model win as well.” “Thanks for your attention.”
—ERIC RULE
Just as with ignition engines, heat is the enemy on electric models. Note the air intakes (above) on the front of the nose as well as the air exits in the rear. Eric employed a method of capturing the motor between two ply walls (at right).
FLYING MODELS
Motor shaft captured by sealed ball bearing
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