Ron van Sommeren

Both Scorpion_Calc and Dualsky_calc are derived from MM_Calc by Louis Fourdan. Probably only different in motor-database. Most recent version can always be found here: http://www.rcgroups.com/forums/showthread.php?t=736782 A compilation of other e-flight calculators: http://www.rcgroups.com/power-systems-13/ -> first sticky thread Vriendelijke groeten Ron

Elektromodellflug site in English Met vriendelijke  groeten Ron

Connector test, in German but the numbers are international of course: -> www.elektromodellflug.de -> Datenbank -> Hochstromsteckersysteme  Vriendelijke groeten Ron

http://www.torcman.de/peterslrk/Warum_dreht_er_so_eng.html -> classic 3-phase drive (I will send my bank account number to the people at Torcman    Don't worry, these articles were written by Peter Rother before the Torcman company existed)   

'Our' brushed and brushless motors are/operate iso-synchronous. Animation & simulations, in- or outrunner makes no difference: http://www.rcgroups.com/forums/showthread.php?t=216928 How does a brushless motor work: http://www.rcuniverse.com/forum/m_1558046/tm.htm Workings of controllers for brushless motors: http://www.torcman.de/peterslrk/index_eng.html -> SPEEDY-BL self made brushless controller Here you can see how motor inductance smoothes out motorcurrent (the higher inductance, the more a coil resists changes in current): http://www.consult-g2.com/course.html -> CHAPTER 9: ELECTRONIC CONTROLLER

Actually Peter, it was Vintage1 on RCGroups who straightened me out on HV systems a few years ago Vriendelijke groeten Ron

Veryvery simplified 'controller', just operate the three on-off-on switches in the correct order to get the idea. The current limiting lamp is essential because at these low (manual) 'frequencies' the motor acts as (is) a massive short!

From the motors point of view, system voltage does not matter, assuming we use motors with the same copper fill factor (preferably maximal of course). Say we want to go up a factor two in voltage. To keep the same rpm (and powerconsumption), Kv has to go down by a factor 2 . In order to get that lower Kv, the number of winds must increase by factor two -> wire resistance increases by factor 2. To make rome for the extra winds, the cross-sectional area of the wires must be reduced by a factor 2 too -> wire resistance again increases by factor 2. All in all, resistance now has increased by factor four. Current is half the original current. And since P_loss = I²R, nothing has changed. On the other hand, losses in the battery-leads are reduced by factor four. And asssuming we use batteries with half the original capacity to keep the amount of available battery energy the same, battery losses are halved because battery resistance doubles and battery current halves. Vriendelijke groeten Ron

Sorry guys, it should read 'cubed increase in power' instead of 'squared increase in power'.  Mike, ask your wife what 'truste' means

alert!! To muddle things a bit more, Increasing the voltage in a BLDC system will give a squared increase in power and a squared increase in motor-current  Vriendelijke groeten Ron int. electric fly-in, Nijmegen, Netherlands NL RC flying forum

New Scorpion_Calc version  (subscribe to that thread): http://www.rcgroups.com/forums/showthread.php?t=736782 Vriendelijke groeten Ron 

Scorpion_Calc and Dualsky_Calc are MM_Calc specials/derivatives, developed by Louis Fourdan from France. Scorpion version also available on http://www.innov8tivedesigns.com/ (US Scorpion distributor). E-flight calculator compilation: http://www.rcgroups.com/forums/showthread.php?t=606703 I have not yet incorporated the 2 or 3 calculators mentioned in the last posts in the compilation. For some reason, editing the numbered list is a pain in the neck,everytime extra returns are added between lines. Vriendelijke groeten Ron van Sommeren • brushless motor building tips & tricks • diy brushless motor discussion group • Drive Calculator download & discussion group

Start your car engine and let it tick over stationary. Now turn on the headlights and rear-window de-fogging. You will hear the motor sagging a bit because now it's more difficult to crank the alternator.  Vriendelijke groeten Ron

More cogging, user 'Martin_G' ("Götzenberger") designs the statorshapes for Scorpion: http://www.rcgroups.com/forums/showthread.php?t=859562 Vriendelijke groeten Ron

'flus' = flux 'schwankug(en) = change(s), variation(s)

See the pictures here, 'rasten' = 'cogging' : http://www.powercroco.de/rasten.html

Cogging, or the lack of it, is not a good indicator for quality, power, efficiency, torque, magnet stength etc. Too many parameters effect cogging, Timbo already mentioned a few. Also statortooth geometry, ironquality (magnetic), flux ring iron quality and thickness, magnet shape, gap between magnet and stator, gap between magnets themselves, magnet mis-alignemnts (radial and axial, skewed) and ratio of #statorpoles <> #magnetpoles. The closer this ratio is to 1, the lower the cogging (3slot/2magnet versus 60slot/62magnets). However, a ratio of 1 will give excessive cogging. That's no problem because a with an equal number of magnetpoles and statorpoles motor would never start by itself. Cogging is not effected by number of winds and Kv, it's a magnetic effect, not an electric effect. The rotor wants to take a (locally) position were the energy in the system is the lowest (and resistance against flux, magnetic resistance a.k.a reluctance is the lowest too). When shorting the motorleads you will feel more 'cogging'. This is not cogging but the effect of the motor operating as a shorted generator. Vriendelijke groeten Ron

A Kv=1000rmp/Volt motor on 2 cells 'is the same' as a Kv=500rmp/Volt motor on 4cells.

Not quite, the above only applies to motors of the same make and type that only differ in Kv. Ohms law is not what you should apply here, not used at this point. Resistance 'only' plays a role in efficiency. Kv is not affected by the cross-sectional surface area of wire, or wires in parallel. But, the lower the area, the higher the resistance, the more rpm will collapse under load, the motor’s 'stiffness' is lower. As long as wire is not too thin, resistance does not effect Kv. A motor is not a simple resistor where current goes up linear with voltage. Current goes up with voltage squared. Double the voltage and current will go up by factor of four! A voltage increase of 50% will give a current increase of 125%. Going from 3 to 4 cells gives a factor 4/3 in voltage and a factor (4/3)^2 = 1,8 in current, an 80% increase. To keep the current within the motors limits, you'd probably have to prop down. Motors, brushless or brushed, don't have a voltage range. They can run at any voltage, provided it does not exceed its rpm, or its insulation limits (voltage would kill you anyway if it were that high). It's the current in combination with not enough cooling that can kill. A voltage rating is just something the marketing departments come up with. Current (and power too) goes up cubed with Kv. A 20% higher Kv and current wants to increase by factor (1.2)^3 = 1,72, an increase of 70% in current! Mind you, this is theoretical, I ignored resistance. Because of the wire resistance, the motor 'sees' a lower voltage, and rpm increase will not exactly be according to Kv*voltage. Therefore, current will not increase exactly cubed with rpm. Furthermore, I'm assuming the battery and controller can supply the current. Vriendelijke groeten Ron

My 'perfect sync' only applies to brushless controllers, not to brushed controllers.  Vriendelijk groeten Ron

And if it works, the motors would be in PERFECT sync, you would not hear that lovely typical multi-engine sound (= beat??) Prettig weekend Ron van Sommeren near Nijmegen, the Netherlands int. electric fly-in http://home.hetnet.nl/~ronvans/