USA # 3-1999

Bleriot XI Electric Conversion Part2
RC-04FR BLERIOT XI DATA SHEET

Would you believe 1/5-stand-off-scale Bleriot XI is an almost-ready-to-fly model! Why gunk it up with Gas when you can go clean with electric power! Read on, and we'll make it fly.
	If you have ever seen the 1965 movie"Those Magnificent Men and Their Flying Machines," you can't help being captivated by the slow-flying, elegant aeroplanes that participated in this fictional 1910 race. Though not specifically depicted in this movie, the 1909 Bleriot XI Channel Crosser captures the essence of the era and was cer­tainly the prototype for the planes shown, as it was the first aeroplane to be designed with a fuselage for the pilot to sit in. Upon reading that an almost ready to fly (ARF), stand-off scale, 1:5 version of the Bleriot XI was being imported by 3 Sea Bees Models, I just had to fly one with electric power, even though this model was designed for wet power.
Aveox 1406-4y motor with Planeta gearbox and 13x8 Master Airscrew electric propeller will pull our Bleroit through the sky.
This project, however, provided several unique challenges for an electric conversion -requiring some trial and error. First, this design has the propeller located directly in front of the wing, which could make it diffi­cult to position sufficient weight forward to achieve the recommended center of gravity (CG) location. Next, the Bleriot XI, with its numerous exposed wing support wires, wing warping wires, and open sided fuse­lage, will make for a model with a lot of drag, possibly much more drag than would be expected. Finally, the author is primarily an electric sailplane pilot with limited "power plane" experience.		This is how the components come out of the Box! And, it is all packed with care as each component is individually poly-bagged asd sealed.
Further, I was taxed because preparing for and competing in the 1998 AMA Electric Nationals in Muncie, Indiana delayed the start of construction of the Bleriot XI until August 10, 1998. And, I want­ed to have the Bleriot Xl's first flight at the KRC in Allentown, Pennsylvania on Saturday, September 19, 1998.
Twenty 2000.mAh "zapped" Sanyo cells provide the fuel for flight. The batteries had to be placed as far forward as possible due to the Bleriot's extremely short nose moment.	The Bleriot XI electric conversion  will be considered a success if:  1.Electric takeoff weight is the same as the wet powered version.  2.It has a flight time of at least 4 min­utes, with an adequate safety margin after that for landing.   3.The battery configuration fits inside the fuselage and still provides an opera­ble CG. Motor Sizing/Battery Configuration ­Round 1  Because of previous excellent results, my choice for power was an Aveox brushless motor. I contacted Matthew Orme at Aveox, who was very helpful and supportive of this project, and within ten minutes it was decided that the proper setup would be an Aveox 1406-4Y with a 3.7: 1 Planeta gearbox, using an M160 controller on 16 nicad cells, and swinging a 14 xl 0 propeller. Here is the decision-making process that was followed, including perfor­mance-confirming calculations. 1.Using Orme's Law: 1 cell per 50 square inches of wing area for a shoul­der wing plane.  832 square inches -7- 50 square inches/cell = 16.64 cells... 16 cells (Note: it is expected that fewer cells would be okay because the Bleriot XI is expected to be a docile flyer.)  2. With 4 minutes (0.06666 hour) minimum flight time at full throttle and using 2000 milliamp-hour (mAh) cells (2 amp hour), the maximum amperage was calculated to be 30 A.  amp hours / hours of minimum flight time = amp maximum capacity 2 amp hours / 0.06666 hour = 30 A, max. 3. Motor choice to meet these parame­ters: Aveox's 1406-4Y with Planeta 3.7:1 gearbox, using an M160 controller (4­21 cells), with a 14xl0 propeller on 16x2000 mAh cells will provide 80 ounces max thrust at 30 A. To give a degree of confidence that actual flight characteristics will be acceptable, the following calculations were made: 1. With a target weight of 129 ounces (the wet power takeoff weight of the prototype, including 16 ounces of fuel), the maximum thrust of 80 ounces equals a 62% thrust-to-weight-ratio, which is adequate for an agile sport flyer.  2.30 Ax 16 cells (at 1 volt per cell) = 480 Watts input power  129 ounces = 8.06 pounds 480 Watts / 8.06 pounds = 60 Watts of power per pound (power-to-weight ratio). This is indicative of an agile sport flyer.
To save weight, HITEC/RCD radio components were used including a Micro 555 receiver, HS85BB mighty-micro rudder servo, HS225BB super mini.micro elevator servo, HS225BB super mini-micro wing warping servo, and a JR Radio, 800 mAh four-cell receiver pack.
[You can increase the battery pack to 20 cells = 600 Watts of input power and the resulting new target weight of 8.56 pounds will still provide an improved power-to-weight-ratio of 70 Watts per pound. However, this is the absolute maximum power (Watt) limit for this motor.]   It was also decided that the 2000 mAh nicad cells will be of the "zapped" variety made by Steve Belknap at Diversity Model Aircraft. These cells provide a noticeably higher running voltage per cell that allows for lower amperage draw at a given power (Watt) level, thereby increasing flight duration possibly 20-30 seconds per flight. That doesn't sound like much, but in a 4- to 5-minute flight envelope, it could mean the difference between a controlled powered landing and a deadstick disas­ter (more on that later).
Kit Description Bob Brooke at 3 Sea Bees Models was very interested in seeing one of his Bleriot XIs with electric power. The almost three-month wait for the kit, caused by importing delays at the Philippine manufacturer, was well worth it. The ARF kit arrived in a large box with every component packed in a heavy sealed polybag, and wrapped in yards and yards of bubblewrap. The packaging showed real diligence and everything arrived in perfect condition. My initial impression was quality, quality, and quality. Not museum/mas­ter scale quality, but more quality than any sport scale modeler could ask for, at the savings of hundreds of hours of work to reproduce. The Bleriot XI is covered neatly with antique Solartex on the wing, rudder, stabilizer, and the cockpit portion of the fuselage. The for­ward fuselage is veneered with Philippine mahogany -a unique touch. Also provided is an aluminum cowl, wire wheels, a dummy three-cylinder engine, and a "display only" 18-inch sta­tic propeller. A complete hardware package is also included with the brac­ing/ control wires cut to length and completely fabricated with ends swaged and quality clevises attached. The only items I fabricated were six servo arm connectors for the .push/pull wires. These were made from 0.047inch music wire and consisted of a zbend immediately followed by a 1/8inch-diameter closed loop to accept the pre-formed swaged cable end. This would provide rotation at the servo arm without chafing the wire end. Personal preference also caused me to stiffen the elevator horn/elevator joint with a large epoxy fillet and the installation of 1/ 16-inch -inside-diameter brass bushings in both the elevator and rudder horns (four places) for the push/pull clevises to fit into, to minimize wear. The instruction manual that was supplied is still under development and lacked some critical setup information. But a call to Bob Brooke at 3 Sea Bees Models provided a quick response with the missing information. Feedback from this project will help fine tune the instruction manual and provide an electric power addendum.
(Table 1) Adjustable Component Weights
Wet Power (ounce)        23.0       12.5       3.5       16.0              55.0 ounces	motor assembly                flight pack motor mount  fuel/battery (16 cells)	Electric Power (ounce)       10.0       7.5       0.5       33.0       51.0 ounces
Weight Savings/Tradeoffs The takeoff weight goal of 129 ounces (8 pounds, 1 ounce) was equivalent to the wet power prototype that uses an OS 0.60 with a 16-ounce fuel tank (see Table 1).  The actual flight weight is projected to be 4 ounces less than the wet pow­ered prototype. Not a significant weight savings, but an achievement all the same, if everything works according to plan. The 5-ounce flight pack savings was achieved by using HITEC/RCD electronic components, including a Micro 555 receiver (0.70 ounce), HS85BB mighty-micro rudder servo (38 ounce-inches, torque; 0.70 ounce), HS225BB super mini-micro elevator servo (50 ounce-inches, torque; 0.95 ounce), HS225BB super mini-micro wing warping servo (50 ounce-inches, torque; 0.95 ounce), and a JR Radio, 800 mAh four-cell receiver pack (3.50 ounces, weight). The weight savings was calculated including an onloff switch and a receiver pack charging jack. The heavy, wet-power motor mount was replaced by the sheet alu­minum AERO VEE model MM-l elec­tric motor mount made by Stitzer Model Design, at only 1/2-ounce total weight, using the supplied nylon tie-wraps. Therefore, with judicious comi ponent selection, it is possible to supply electric power equivalent to the wet power at approximately the same weight, albeit, with somewhat shorter flight duration.
(Table 2) Aveox 1406.4Y jPlanetaj 20x2000 mAh Zapped Cells
Propeller Thrust (oz) AMP Volt RPM 13x6Zinger 61 19.0 22.2 8,400 13x7Zinger 68 26.5 22.2 8,000 13x8Zinger 67 27.6 22.2 7,900 13x8MasterAirscrew.electric 74 31.5 22.2 7,500
Equipment Installation / CG Location The cavernous fuselage allowed more than enough space for the 16-cell X 2000 mAh motor pack. There was also plenty of room for the radio equipment in the lower forward section of, the fuselage, with everything concealed except the wing-warping servo. It should be noted that, to prevent stalling the wing warping servo of 50 ounce-inches torque (Hitec/Rcd'. HS225BB), required a maximum 1.00. inch distance between the cable connections at the output arm. With the 1.0-inch servo arm spread, adequate! throw was still achieved. The only real" construction" required with this ARF, involved the rudder installation. The two rudder; hinges were epoxied in place with two 1/8-inch dowels installed through the rear post to lock the hinges in place. This construction was necessary so the fuselage could be shipped in a shorter configuration, sans rudder, to allow smaller shipping box. The motor was installed in the AERO VEE mount with tie-wraps and, bolted to the firewall with 4-40 socket. head screws threaded into T-nuts. The motor controller was Ve1cro-mounted to the firewall just above the motor. The wing warping wires were coordinated to provide approximately 5/8 inch movement up and down, while maintaining 1-inch of washout in each panel. The wing warping / washout setup was a real educational process for m, and took approximately 3 hours. The rudder was set for full throw of +-2-1/2 inches. The elevator horn was modified slightly to allow for 1-1/2 inches up and 1-1/2 inches down. The recommended CG location w 20% to 25% rearward (in back of the wing leading edge). This seemed too far forward to me because of the lifting tail and large tail volume, which, on my Old Timer electric sailplane, required a 65% rearward CG. Bob Brooke was kind enough to give me a list of eight modelers who had taken delivery of Bleriot XIs, in the hope that one of them could shed some light on how their plane's CG was set. Of the six I contacted, only one had his Bleriot XI flying -Burf Tunnell of Rancho Santa Margarita, California. Burf had first set up his Bleriot XI with the suggested 25% rearward CG and used a Saito 0.56 four-stroke for power. However, the Saito 0.56, provided only marginal power. While on the landing approach for his first flight, the engine quit. Because of the forward CG, the sub­stantial drag of the bracing/control wires and the limited up-elevator throw of I inch, as supplied, the plane nosed over and he was not able to level it off. This caused a severe impact on the spring-loaded landing gear assembly, but nothing broke. He subsequently changed the motor to a Saito 0.70 four­stroke, moved the CG back to the upper wing warping pylon, approxi­mately 40% rearward, increased the up­elevator throw to I -I /2-inches, and installed I inch of washout in each wing panel. He has since flown the Bleriot XI several times with this con­figuration and is very pleased with the docile flying style of his Bleriot XI. Burf also suggested that the takeoff should be at full throttle and directly into the wind, just like the original Bleriot XI. Not wanting to "reinvent the wheel," I incorporated all of Burf's suggestions, and have been very pleased with the results. But a problem arose! The 16­cell motor pack was not heavy enough, even when right next to the firewall, to allow a CG any further forward than a 50% rearward location -too far back for a safe first flight. A 20-cell pack moved all the way forward was required for a 39% rearward CG. The 20-cell pack layout is shown in the photo.  Now for the second round of calcu­lations.
Motor Sizing/Battery Configuration -Round II But how would the 20-cell motor pack affect the motor/prop configura­tion? I called Matthew Orme at Aveox again and he said this would be no problem as the extra cells would provide "friendly weight" when more cells convert to more duration at constant input power. That is 16 cells at 30A max = 480 watts and 480 watts from 20 cells = 24A max. Therefore, he rec­ommended a I3x6 propeller with 20 cells on the Aveox I406-4Y with the 3.7:1 Planeta gearbox, to again give approximately 80 ounces of maximum thrust, now at 24 amps. I was keenly aware that, potentially, my original fly­ing weight goal of 129 ounces had now gone up to 133 ounces (8 pounds,S ounces) with the four additional 2000 mAh cells. After completion, the actual flying weight on my first flight was 8 pounds, 4 ounces, only 3 ounces above my target, an insignificant amount I rationalized. The motor wiring was completed and although I briefly thought about installing a fuse into the motor power system, no fuse was installed. This was one time when my electric sailplaner's mentality would lead me astray, but not the only time. To this point I had spent a total of 30 hours on the project. But most of this time had been spent on the engi­neering phase. To the manufacturer's credit, the actual construction/installa­tion/control setup time was less than ten hours when using the above infor­mation, and I'm a slow builder.
Motor Static Testing To provide some comfort level before the initial flight, I decided to test a series of propellers with a fully charged 20-cell pack to observe their relative performance. The thrust was measured using a 50-pound electric fish scale, attached to the rear of the Bleriot XI using a bridle. The plane was raised at the rear and allowed to rest on its wheels. I am well aware that the absolute level of the test results will be suspect for many reasons, but the rela­tive performance should be revealing. Table 2 shows the results. These test results said three things to me: 1. The I3x8 Zinger propeller is inferior to the 13x7 Zinger. 2. Although the 13x6 Zinger was the most efficient at 3.21 ounces/A, the maximum thrust of 61 ounces seems only adequate for cruise and suggests questionable takeoff reserve power when 80 ounces of takeoff thrust was expected. 3. The 13x8 Master Airscrew electric propeller provided very close to the expected maximum thrust at 74 ounces, but the 31.5A reading was mar­ginally above the recommended maxi­mum power rating of the motor -600 Watts. My electric sailplaner's mentality grabbed hold of me again and I decided to try the first flight with the 13x8 Master Airscrew electric propeller. Why? Because I wanted a maximum thrust safety margin so the plane would take off as quickly as possible to avoid any ground handling mishaps. (Sailplaners believe that planes almost never break in the air, so we like take­offs to be by hand launch; and landings are done very slowly.) The higher than suggested maxi­mum amperage with this propeller was considered nominal and should allow for a 3-minute initial flight with reduced-throttle cruise settings
Bleriot XI Electric Conversion Part2>> RC-04FR BLERIOT XI DATA SHEET>>