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Electrifying the Ace Bingo!

Notes on Converting the Ace Bingo to Electric Power, adapted from an article by Bob Rumsey

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Okay, I admit that I am guilty! I am... a kit basher. Not just your run of the mill kit basher, but one that converts gas kits to electric and enjoys every balsa stick of it.

For those of you who might be considering converting a gas kit but don't know where to start, here are some of the key factors that I consider when looking for a good conversion subject: Ample wing area (to account for increased battery weight), low overall initial weight (pick a kit that already has a lightweight design), and overall size and design (to allow enough room for batteries, easy access to motors and connectors, etc).

I chose the Ace Bingo because I felt that I could convert it for easy access to the motor pack, I could build the wing for 720 sq. inches of area and because I already owned the kit. I had originally purchased the kit to convert to a 60 with 28 cells, but the more I studied the plans the more I felt it would be a good subject for my conversion to a geared 40. I am happy to report that the choice was an excellent one.

I only made three modifications to the kit. They consisted of balsa fuselage sides in place of the lite ply, replacing some of the spruce spars and turtle deck stringers with balsa (the lower wing spar was reinforced with carbon fiber) and installing a balsa hatch for the power batteries in place of the plastic forward deck. I also added a balsa cowl to enclose the motor and streamline the structure. Of all these modifications, I would say that the most important change was the substitution for the spruce spars and turtle deck. These were no light weight 1/4'' square spruce but rather 3/8'' x 1/2'' main spars and 1/4'' square secondary spars top and bottom on each wing and 3/16'' square for the turtle deck. The 1/8'' square spruce turbulator spars were retained for the wings. NOTE that I reinforced one of the main spars with carbon fiber. I do feel that the main spars should not be changed unless some type of lightweight - high strength reinforcement is used. Fortunately the landing gear mounts directly to the fuselage so the carbon fiber on the lower spar is enough to handle the flight loads. To date I have performed all types of snaps, high speed turns and inverted flight with no sign of structural problems. I should mention that I built the shorter wing version with 720 square inches of area which, as I noted before, was at the high end of what I felt the required wing area should be. The total weight reduction was about 8 ounces with the spars being almost 6 of the 8.

I had decided that I wanted a larger plane that I would fly routinely. That meant several packs to provide extended time, so the forward battery hatch provides access without taking off the wing. The hatch was easily constructed from 3/16'' balsa and a Foremost recessed hatch release. The bottom of the battery compartment is 1/8'' lite ply (see you can still use part of the fuselage sides) glued to the top of the 1/4'' balsa wing saddle doublers. If you make this modification be sure to allow extra room in the compartment so the batteries can be shifted to adjust the CG. Once their correct position is determined, I use stiff foam to fill the excess area. The cowl was made from 3/16'' balsa sides some triangle filler and 1/2 inch balsa front. Notice that very little of the 1/2 inch front remains after shaping and hollowing. The completed cowl weighs 2 ounces covered.

Other weight reduction was gained by using such products as Sullivan Skylite wheels and the new relieved back plate offered by Tru Turn. The total weight of the Tru Turn all aluminum spinner with this new plate is equal to or less than the plastic models of similar size. I used the 3 inch FAI model and the fit is great. I also tried the speed control offered by Ace and have found it to be as advertised and then some. The speed transition is very linear, it has a failsafe startup mode in case your throttle stick is advanced when the control is powered up and it self adjusts to the frame rate and total stick travel of your transmitter.

With a Zinger 13x6-10 up front, the Bingo will really move. Almost any maneuver that does not require extended vertical flight is possible plus the plane is a pussycat to fly at slow speeds. In fact, even the initial elevator throw of 1/2 inch was not enough to create a stall at low speeds. Instead the plane just went into a mushing descent and this was with the CG near it's aft limit. I have also flown the Bingo with a Rev Up 13x7 which provides a more docile flight and reduces the current draw for slightly longer flights. For a gas to electric conversion using the Astro geared 40, I would certainly expect similar results for a variety of other 40 sized glow designs.


next up previous
Next: Until Next Month... Up: Front Page Previous: Engine Airleaks: Cause and

Craig Kulesa
Fri Dec 4 19:15:29 MST 1998