An update on Electric Control Line Aerobatics
Blue Tooth, Blue Ray, HD, WiFi, Broadband, DLP, 802.11n, GPS, XM Satellite, GMS, SMS, WAP, I-mode, GPRS, MMS, CDMA, TDMA, D_AMPS, Fuzzy Logic, CMOS, MOSFET, MEMS, NEMS…………….etc, etc, etc.
Feeling left out yet? I could go on for a few more pages but if you do not know the meaning and application of the terms above, you are OLD!! (and these are just the easy ones!)
This is the world of a child celebrating his\her first birthday today. They will use, manipulate and redefine these and many other standards for their own purposes in the years to come. In all likelihood, the first car they will drive will be a Hybrid or pure electric powered vehicle. The first plane they will fly in will be able to make a trip to any major airport without the pilot touching the controls except for taxiing out to the runway. If they need a new body part or need to repair an existing one, one will be grown specifically for that purpose and it will integrate with their existing body without rejection.
Children do not wear wristwatches anymore. Instead, they look at their cell phones to tell the time. The amount of pure technological information they are asked to assimilate and make use of is staggering.
Children born today will laugh at you when they are teenagers if you try to tell them that small two or four stroke IC motors are an efficient use of technology to power a model plane. Almost everything in that child’s world is electronic, portable and powered by hi-tech batteries. Right now, battery technology is evolving at the rate of about one generation per 1.5 years. By the time our newly born child is fifteen, he will likely have seen some twenty to thirty more generations of battery technology pass by.
Yes, that’s how fast the world is changing. Your only decision is in how you are going to deal with the inevitable change. It is not something you have any control over. Moreover, it is not something to waste your time trying to. Life is short, far too short to erect artificial barriers to insulate ones self from the inevitable.
The state of Electric powered control line aerobatics:
Few people have seen an electric powered control line plane fly. Fewer still have flown one and even fewer still have built one. There are lots of opinions but little hard fact. So if I may, I will offer some facts and the occasional opinion on just where we are.
Q:
How competitive is an electric powered plane vs. an IC powered plane?
A:
It is both my own opinion and that of people you all highly respect that at the top level of competition, electric gives nothing away to other power trains. It is my humble opinion that smaller size electric power trains although adequate for sport flying are not able to match the performance on a size for size basis with comparable IC power trains. This is the result of economies of scale and power and can not be solved at the present by just building lighter.
Q:
Is electric power more or less expensive than IC power?
A:
If you do not already have the chargers, balancers, power supplies, extra batteries and electrical testing equipment then it is SUBSTANTIALLY more expensive. If you have all of the above and you are looking at the basic cost of a medium priced basic power train (motor, ESC, one battery, timer) then it is probably only TWICE as expensive as a similar .40 powered setup for a plane the size of a Twister. At the upper end it is about the same as full tuned pipe P.A. .65 setup. (not counting the support equipment or batteries)
The complete power train and support equipment for the most basic setup (not including plane) will cost you a bare minimum of $400.00. And at that you will have only two batteries. Five batteries would be the bare minimum to sustain a day of flying while charging and eight to ten required to be competitive.
Q:
What is the lifespan of the batteries in an electric powered setup?
A:
That depends to some extent on how much you paid for your batteries in the first place, what type of equipment you will be using to charge them, The rate that you will charge them and what type of environment they will be used in. High quality batteries cost more. High quality, LiPo specific computer controlled chargers and balancers cost more. The current thinking is that a new Thunder Power ProLite battery pack should last upwards of three hundred cycles or more if handled properly.
It should be noted that if you are not well beyond the stage where you are still crashing planes, then you should not consider electric flight. LiPo’s have a thin aluminum foil skin and will not tolerate a crash. Further, if you are new to the game you should know that a LiPo battery can EXPLODE!! up to fifteen minutes after it has been abused either in a crash or by improper loading during use or charging. Do not put one in your car to charge or after a crash and walk away!
Q:
Do I need to purchase the testing equipment sometimes suggested?
A:
Yes. This is not just for the “Pros”. You can not “see” electricity and you can do yourself or someone else a lot of harm if the various components are not hooked up properly or if they are not functioning as they should. The voltages we are playing with in larger planes can hurt you. You should have a WattMeter or E-Meter and a good Digital Multimeter at a minimum and an IR Temp gun to monitor battery pack, motor and ESC temps.
Q:
Can I save money by starting with a smaller system?
A:
Not as much as you think and only if you never want to move to a bigger system. Remember that the most basic setup will cost you about $400. For that, you will get small batteries, a charger and balancer that will only work with lower cell count batteries and an ESC that will not handle higher amp draws. All of these will need to be replaced at substantial cost should you wish to move up to a “full size” competitive ship.
Q:
What happens if they change the shape, size or weight of my battery?
A:
Therein lays a problem. The fuel for an IC powered plane always has the same shape and virtually the same weight. (Hence the design can remain the same for all time) The fuel for an electric powered plane comes in a physical form of differing weights, strengths and physical dimensions. SHOCKWAVE was only designed to work with (and can only physically accommodate) one battery, the Thunder Power ProLite 5S2PB 4200 mah brick battery pack. This pack and its technology were only four months old when I started the design. It took more than a year to design and produce the first plane. In that time, Thunder Power announced a new chemistry (TP Xtreme) and this resulted in a whole new series of weights, dimensions and strengths NONE OF WHICH WILL FIT INTO SHOCKWAVE !! I am not complaining mind you. There is no level of performance that I need that this package can not produce, at least any that I am currently aware of or feel a great need to possess. But the day will come (I am giving it a year at best) when Thunder Power will no longer produce that battery in those dimensions. This will occur for ALL current Lipo batteries regardless of manufacturer at some not too distant point! On that date SHOCKWAVE would not be worth building again. A whole new airframe based on the new battery weight, strength, and physical dimensions would need to be designed.
Q:
I have read that electric power trains are pretty simple compared to IC?
A:
If you mean that you can throw a switch and the engine springs to life then yes. If you mean that there is no challenge in developing an electric power train then you are in for a rude awakening!
Starting with the battery, you must decide which form factor, the number of volts, the number of amps, the number of cell in series, the number of cells in parallel, the required “C” rating, how you will mount it, how you will cool it, how you will remove it, how you will connect it, how to break it in, how much to charge it, what to charge it with, when to charge it and how to measure its various parameters.
Brushless out-runner electric motors are complex. You can change and may want to know the impact of changing the number of poles, the number of winds, the gauge of wire, the type of wind whether WYE , DELTA, STAR, the air gap, the type of magnet, the length and thickness of magnets, stator core material properties, motor shaft support, the diameter and length of the stator, type of case material, balance of rotating parts and cooling.
The Electronic Speed Control (ESC) is no less complex but if you are going to make improvements here you will need to know some hardcore electronics and be able to understand complex logic. Not all ESCs are made the same and not all Governor modes function the same. If you really want to have control over this environment you had better become fast friends with the guy who made your ESC since without his help, you will not achieve the results you had anticipated. Will he want to become fast friends with you? Not likely.
The timer/processor is no different. To make one yourself, you will have to know a fair bit about electronics and if you want to manufacture one then you will need to deal with surface mount technology and embedded programming.
So do you really need to know all of the above? No. But simple or lacking in challenge it is not!
Q:
Can I retrofit an electric power train into an existing model?
A:
While it may by possible to mount all of the components somewhere in or on the fuselage of an existing plane, I think the most likely outcome will be a nose heavy model. This would be OK if your intent was only to test various components for future use. If you want competitive performance, you may be disappointed. Check out how the battery is mounted in the electric Clown. The battery in SHOCKWAVE is mounted more than one inch inside the leading edge of the wing and the nose moment is shorter than a normal IC powered stunter.
Smaller systems do not generate as much heat as larger systems and you may get away with just mounting things where they will fit. In larger planes, the battery, ESC and motor will need to be cooled since they will be run at almost full power for the duration of the flight. There are also limitations on the length of cables you can use from the battery to the ESC and then to the motor.
At a minimum, I would suggest that you start with either a kit and modify it for proper balance from scratch or use an ARC (like the Vector 40) and rebuild the nose from the wing forward. In any case, your tail moment will probably still be too short to balance properly without the addition of extra weight. As a benchmark to compare where you are weight wise, SHOCKWAVE weighs 38 ounces as a full take apart, fully painted 710 square inch model. The plane less battery weighs 54 ounces and with battery 70 ounces.
The best result will come from building a plane which is matched to the chosen power train and is structurally optimized for electric power.
Q:
Are the AMA and FAI trying to eliminate the use of existing IC model engines?
A:
Nothing could be further from the truth. I am not aware (and I am reasonably well informed) of ANY movement to limit or reduce the use of IC model engines in control line aerobatics. You see they don’t have to. The society in which we live is doing a bang up job of seeing to it that if we want to continue to fly at many sites, that we modify the manner in which we do so. So if you want to fly “Shelf Line” (that the new event where old geezers sit at Formica tables in their polyester pants and white belts and drink coffee from melmac cups while engaging in exciting conversation about the models that line the shelves of their hobby rooms) then just stick your head in the sand. Personally, I want to continue to fly my models ON the CIRCLE at the PARK. That said, I think it will be some time if ever before the above organizations need to enforce a ban on IC engines. I fully intend on going to the VSC someday soon with a sparker.
Q:
Are the rules governing the use of electric models slanted in their favour?
A:
If you mean have the rules been modified to enable electric powered models to start and stop on command and thus be able to be used the answer is yes. If you mean is it a good idea to promote the use of modern technology to our new born child above, the answer is also yes. If you mean do they enjoy an unfair competitive advantage over existing IC engines the answer is no. At best, they are on a par. If you can think of a model that can not be powered in a competitive manner with a .90 two stroke and tuned pipe, then you are not current on the state of modern IC model engines. After all, the motor is only turning the prop, it is not moving the handle.
The rules are constantly under review and if ANY unfair advantage was perceived by the rules makers, it would be acted upon. This is the case with the rationalization of engine displacements to .90 for both two and four stroke.
Q:
Should electric power be allowed in OTS?
A:
IMHO, Unless and until the society in which we live or some other authority tells us that we can not fly our old IC engines or we simply run out people interested in flying the event, I do not think that electric should be permitted. You see as much as I embrace the hi-tech world with open arms, I truly love the spirit of an event that was enacted to preserve the past. No electric in OTS. I have no issues with it being used in Classic although I think you would have a hard time putting a competitive package together.
If you love model aviation or all of aviation as I do, you will realize at some point that you have a responsibility to protect and preserve the best elements of what you have participated in and pass them on to someone else hopefully much younger that yourself. If control line flying survives for any great period of time, it will be with battery powered electric motors on the plane and young people who know what all of the gibberish at the top of this post is all about.
I invite your comments
Kim.
Topic: Electric Control Line Aerobatics - an update on where we are (Read 2607 times)
