The Ampeer ON-LINE!
May 2010
The Club Newsletter of the Electric Flyers Only, Inc
AMA Charter 2354
Walled Lake, MI, USA
Editor: Ken Myers

Fly the Future - Fly Electric!

     I love this meet. There is a lot of laid back flying with some of the Midwest's best pilots, Electric Flight Designers, Builders and Authors. I wouldn't miss it! It is a lot of fun for everyone with an interest in electric flight. KM

     The 2010 Mid-America Electric Flies (Mid-Am) will be held on July 10 & 11 at the MRCS 7 mile Rd. flying field in Salem Twp., MI.

Flyer Here

Map and Hotels List Here

Hi Ken,

     I felt well enough to fly today. I maidened the Contender ---WOW! I think it is going to be my "go to" plane for this season. It took off like a rocket -- straight up! Oops, full down trim. Perfect. Two clicks right aileron -- dead-on. I flew most of the flight at 2/3 throttle. Man this baby gets SMALL in a HURRY! Stalls are a non-event. Maybe that was because she was slightly nose heavy on the first flight. It still took almost no elevator when inverted so the CG (fore-and-aft balance) must be close.
     I tried the flaps. Wow, there was major ballooning and a drop off to the right. A touch and go with no flap was awesome! I did a few more loops rolls, stall turns, attempted spins and then it was time to land. Smooth as silk! Now I gotta get me a 60 size!

     The April 1 EFO meeting was held at Ken's house. Once again, the turnout was very good, and we all had a great time. Many of us were excited because the "official flying season opener" the Toledo RC Expo was coming up fast.

     Rick Sawicki brought his latest control line electrically powered model, the Legacy, to share with us. Rick has been doing electric control line for at least six years now. He was, in his younger days, a top competitor in control line, along with his father.
     The airframe was constructed from a Brodak Legacy kit with some parts substitution and modifications made by Rick. www.brodak.com

     He has built a motor hatch and mounting system so that he can easily change between an AXI, Scorpion and Arrowind outrunner. You can see his special mount in his hand in the picture of the three motors. It has an AXI mounted to it right now.

     Rick uses a standard Castle Creations ESC that is controlled by his timer/controller. He uses the helicopter governor mode to keep his up-lines and down-lines at the same speed. The Will Hubin timer controls the voltage to the ESC and the time. It sells for about $23.
     If you have questions about control line flying using electric power, Rick would be happy to answer them for you. You can reach him via email at rrrjjjsss@aol.com.

     James Frolik, who lives in Cologne, Germany, sent Ken a DVD of John Borgen's DC-9-21. Jim sent along the following via email as a background.

     About ten years ago an R/C modeling acquaintance introduced me to John Borgen of Copenhagen, Denmark. Earlier John had undertaken an ambitious project to build an EDF model replica of Scandinavian Airlines System's (SAS) very first Airbus, an A300-B4. Ironically he was not a crazy EDF modeler himself, but just a casual eflight hobbyist, and, most important, an occasional R/C scale modeling judge. Yet he had a burning desire to build an electric ducted fan modelÑactually a semi-tribute to SAS-of a commercial jet that is something not really seen at scale competition events.
     Many modelers in Denmark, Germany, and elsewhere in Europe were surprised by John's fine craftsmanship and attention to detail, even with his homemade wooden EDF units. His Airbus eventually flew, first in 2001, and today hangs undamaged in his basement. It was replaced by his next ambitious and even more detailed DC-9-21, Rane Viking, a replica of the last SAS DC-9 in service and which his good friend, SAS Capt. Torben Sorensen (retired), ferried to the airliner storage boneyard about 7 years ago at Roswell, New Mexico.
     John and Torben had become good friends when both were active R/C scale modeling judges. This friendship encouraged John to build a DC-9 EDF model because Toben had logged over 12,000 as Pilot-in-Command in this type and his association allowed John access to SAS hangars to inspect and measure Rane Viking (and other DC-9s). Torben eventually retired about 6 years ago as SAS's most senior captain, having logged over 20,000 hours. So it's slowly becoming clear this EDF model has an interesting history, with actual napkin sketches dating back to 2001.
     Throughout John's EDF endeavors he's had Ralf Dvorak as his designated R/C model pilot. Their association was established via the EDF and scale modeling grapevine. An R/C modeling enthusiast for as long as he can remember, and also an expert EDF modeler who's flown for the German National Team, Ralf professionally flew the Canadair Challenger 601RJ for the German Air Force and often had German government officials as passengers, including the German Chancellor. A few years ago he left the German Air Force and is now a captain at NetJets Europe where he flies the Hawker 800XPC bizjet. Without a doubt the combination of John, Torben, and Ralf makes a highly talented team.
     And Ralf Dvorak is that acquaintance who introduced me to John Borgen. During his Air Force days he was based at the Cologne/Bonn Airport when Bonn was still the German capitol. Upon seeing John's Airbus I had a good feeling there was a beautiful story-and more to come.
     With John's DC-9-21 that "more to come" is here-and it hasn't stopped building momentum. As a hobbyist photographer and videographer, I decided to offer my assistance documenting Rane Viking's first flights. It also offered me a good reason to learn Apple's movie editing program, Final Cut Express (which isn't really an express, but certainly a bit more streamlined and less expensive than Final Cut Pro). Additionally, as a former full-time performing musician for nearly 25 years, I am quite creative and had some latent visually artistic desires to fulfill. So I enlisted my video services to John Borgen.
     The result is DC-9-21 Part 1, Part 2, and Part 3. I suspect you have already seen some of the trilogy. Part 3 was just uploaded to Vimeo.com on 28 February 2010. So for your next issue of the Ampeer here are the video links and a photo taken by Torben S¿rensen.

Part 1 www.vimeo.com/7043207

Part 2 www.vimeo.com/7043579

Part 3 www.vimeo.com/9814202

Regards,
James Frolik

     James also sent along this nice still of the model in flight.

     During the watching of the video, there were plenty of snacks. Once the group had completed that DVD, Ken put on his video "Electric Flying in the 90's". All of the footage on VCR tape was captured prior to 1990. Some of the newer EFO members had not seen these archival videos and were amazed at what many of use were actually doing with electric power before 1990. Thank you Keith Shaw!
     Our next meeting will be on Saturday, May 1 at the Midwest RC Society 7 Mile Rd. flying field. Everyone with an interest is welcome to come our and join us, and if you have your AMA membership card with you, we invite you to fly with us.

     Happy Easter. Hope you don't mind fielding a few questions but I am transitioning from Ni-cads to lithium after resisting for some time and need some advice. Truth be known, I need lots of advice. I'm building a Cessna 195. It has a wingspan of 59 inches and a predicted ready to fly (RTF) weight of 5.0 -5.5 pounds with a wing cube loading (CWL) of 12.29 oz./cu.ft. I am not a very good pilot, so your data on CWL says I may have my hands full.
     If your model is the one published in Flying Models with the plans and plastics available from http://richuravitch.com and the laser cut parts from www.hobbyhangar.com, then it has 536 sq.in. of wing area. KM

Photo from hobbyhangar.com Web site

     The "kit" is a set of plans and all of the laser cut wood. The rest I have to scrounge. In any event, this overweight beauty can't carry the weight of Ni-cads, which leads me to A123s. I don't care for all the inconveniences of Li-poly batteries.
     Ken, I can't tell you how grateful I am for all the literature you've published on A123s. It has all been saved and studied over and over.
     Unless it's possible to get a lot of weight out of this plane it appears it will need five cells. Radical RC's web site makes a believable pitch on their ability to perform as a quality A123 source for custom packs. Do you have or know of any experience with them re A123s?

     I've made up all of my A123 packs from DEWALT packs, except my first pack, a 6S, which I purchased from Big E RC. I can tell you about Dave Thacker though. He is top notch, first rate, a great guy who stands behind his products! Radical RC is excellent to deal with. I'm sure that Dave can provide you a pre-made flight pack or two at a fair price with excellent work. I've known Dave for many, many years now and Im more impressed with him and his business each time we meet. He is our major vendor at the Mid-Am. He'll be at Toledo if you are driving down. KM

     I need to buy a charger that will handle [I think] Li-poly batteries and A123s with a built-in balancer and up to five cells. What would you suggest?

     Not the least expensive, but one of the absolutely easiest to use with very good power out is the FMAdirect CellPro 10S. I've had experience with several other "upscale chargers" and this is by far the simplest to use that I have personally run across. While not cheap, it is a great value. Be sure to find out what type of balancer plugs Dave is putting on your packs. You'll need that info to order the correct adapter for the CellPro 10S. Using the CellPro 10S at 10 amps, you should be able to charge an empty "A123" 2300mAh pack in less than 15 minutes. KM

     Just one more question before I stop burning up all your time. Compared to Ni-cads how much cooling air do "A123s" need?

     All batteries need cooling, how much depends on the ambient temperature and how much work you are asking them to do. Lithium based cells, in general, like to run a little warm for best power. A little warm means not cold. Don't read that as more than a little warm, like warm or hot! Try to get as much cooling over them as you would Ni-Cads. If it is a bit less, that probably won't be significant to their lifespan. These really are the perfect transition cells for us old Ni-Cad/NiMH users. They are lighter than what we were used to using and just about as maintenance free. They really do need balancing every so often, especially at first. If you decide to go with the CellPro 10S, then you'll always be balancing your packs as the balance lead must always be connected for the 10S to charge. No problem really. That is just the way it is. KM

     Here in southern Brazil we barely felt the equinox changes, our temperatures are still around mid seventies. Only in July we are expected to get some forties and thirties but not less than that. Flying is all year round, when we have the time for that. Right now I'm quite busy, traveling a lot and flying a little less than intended.
     Anyway it is not to complain as we are making good money for that, looking forward to retirement.
     You can take a peek at my flying site in Google Maps at
Flying Field link or at www.conesulmodelismo.com.br only in Portuguese, unfortunately.
     Thanks for your wonderful Ampeer job. Every issue is a gift of joy when it appears at my inbox. And the last one was no exception. I was particularly pleased with Ralph Cook's contribution, since I had done about the same calculations for some motors I had at hand. Only the GWS's used Diameter-Length numbers, but I measured their stators and achieved good correlations with either estimated or published power figures. It seemed natural for me that it should be so, by the reasons herr Cook told us so clearly in his article. I felt the power should be proportional to the stator volume the same way glow engines power is proportional to piston displacement volume. And I guess variations in stroke to diameter relationship change the maximum attainable RPM about the same way length to diameter relationship does in an outrunner, although in inverse relation (smaller stroke/diameter or bigger length/diameter produces more RPM, volumes being the same).
     Internal combustion engines, which have as much stroke as the piston diameter are called "square" and when that relation is below one we call them "super-squares", which are capable of greater rotational speeds. We could also call "square" motors those with same length and diameter numbers, and "supersquares" those lengthier relative to their diameter. On the opposite end, greater strokes/diameter and smaller length/diameter produces higher torque, being capable of turning bigger propellers, for the same volumes.
     Here too, I guess we could find Kv is somewhat correlated to the length to diameter proportion, although the winding counts in each pole also play an important role for which I see no equivalent in combustion engines. I once proposed to use diameter, length, winding count and phase connection to name a motor, e.g. 2304/18T STAR stands for 23mm diameter, 4mm length, 18 turns per pole, star wired phases. GWS small motors are numbered that way, I have a 2212/13T RLK and a 2205/15T RLK.
     Adding more cells has the same effect as increasing intake pressure; add too much and you blow up your machine. Too little cells are equivalent to using a smaller carburetor; it ends up restricting the juice getting into the converting machine, whether it be electrons or fuel molecules. And the pack capacity is akin to the fuel tank capacity; this one is already obvious to most of present electric fliers. The secret will be making the calculations herr Cook did. Once we have all the math done it will be easier to convert almost any glow or gas model to electric simply by comparing motor specifications.
     The first step is standardizing the way we rate the motors, the same way we find in the internal combustion arena. I strongly support using stator diameter, length and Kv (or better yet, stator volume and Kv) as a first approximation to that.
     I enclosed two pictures of myself with two of my planes. One is an electric conversion of a Randy Randolph .049 Bee-tween that I used to fly with revamped CD motors like a 2304/18T STAR.

     The other picture is from my former .25 powered Sturdy Birdy that now carries a Dualsky XM3536CA-8 in the nose, this motor does not follow the proposed standard as it measures 35mm diameter and 36mm length overall, bell and base included. I had not yet disassembled it to take stator numbers. I am the last one from left to right in both photos.

     Take care and enjoy your flying and EFO Meetings!

     My conversion of the E-flite PT-17 Stearman into Super Stearman N56772 is ready for its maiden flight. I have posted a complete description of the conversion on RC Groups at www.rcgroups.com/forums/showthread.php?t=1222582
     Details regarding the power system and my new Hitec 2.4GHz radio system will be in next month's issue.