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EDF FAQ's

Common FAQs about Motors, fan units, ESCs, and Batteries:


Question:  What size motor shaft, diameter, and KV rating do I need for 50mm edf plane?


Answer:  Depends on the maker, the shaft sizes can range from 2.0, 2.3, and 3.0mm’s.  Know your adapter sizes most Chinese fans do not offer different size adapters.  If you use a quality FAN like a wemo, then several adapters are offered. The most common size motor diameter a 50mm fan will hold is a 20mm’s.  When choosing a motor the first number is generally the diameter of the motor. This measurement is so that the motor will fit inside the edf unit. Example of motors numbers would be 18L(usually inrunner motor) the 18 would stand for 18mm’s.  The kv rating can range from 4500kv to 6000kv depending on the number cells used.


Question:  What size motor shaft, diameter, and KV rating do I need for 64mm edf plane?


Answer:  Shaft size, kind of a crapshoot here, 2.3 and 3.0mm are still equally common.  J-power, EDO, Riccs, LX, and Starmax normally use 2.3mm shafts especially if it’s an inrunner setup. The newer Freewing products are 3.0mm (outrunner) but, it’s a good idea to measure what you have so you can choose the proper motor if you are still going to use the stock fan.  A 20mm diameter motor is the most common size for a 64mm edf unit. KV’s range from 3500kv to 5200KV There are some 64mm motors that hold 28mm motors. Thrust ranges can be from 1lbs to about 2.2lbs.  The Norm is 3s to 4s setups.


3s 64mm Motors 4000, 4500, 4800, 5200kv brands on this site (Sapac, Freewing, and Cyclone Power)


4s 64mm Motors 3500, 3800, 4000, 4500kv brands on this site (Sapac, Freewing, and Cyclone Power)


Question: What size motor shaft, diameter, and KV rating do I need for 70 mm edf plane?(70mm is interchanges with 68mm and 69mm fans)

 
Answer:  4.0mm is the norm if your using the stock fan that is included in the kits.  The quality aftermarket edf units are usually 3.17mm with the exception of E-Flite DF15 Delta-V 15 69mm, OkModels, and Sapac. HET makes fans with both adapters sizes and so do Wemotec, Velocity RC, and Shubeler.  Most of the 70mm foam kits are designed for 4s setups and use motors ranging from 2650kv to 3000kv. (NOT VERY JET LIKE PERFORMANCE)  Quality motors on 4s setups start out a 3200kv and go up to 4100kv, you can see gains in excess of 1 lbs of thrust by upgrading the motor and fan.  Like anything though more power will require a better battery and better ESC, Stock edf setups from PNP’s draw around 40amps, a good power upgrade will likely draw 60 to 70 amps but, the performance gains are well worth it. (Jet Performance Assured)

3s 70mm motors range is from 4000 to 5000kv amps draw ranges from 50 to 80 amps depending on the fan unit efficiency.

4s 70mm motors range from 2650kv to 4800kv amp draw ranges from 38 to 100 amps depending on the fan units efficiency. Brands on this site (Freewing, Cyclone Power, ARC, Hoffman)

 


5s 70mm motors range from 2600kv to 4130kv amp draw ranges from 50 to 120 amps depending on the fans efficiency. Brands on this site (LX, Arc, and Hoffman)


6s 70mm motors range from 2100kv to 2950kv amp draw ranges from 46 to 85 amps there is one exception the ARC 28-58-1 it can run on 6s if setup with modified cooling it is 3180kv and the amp draw will be a little over 100amps for experimental extreme setups only.


EDFhobbies is going to be releasing its own line of motors after researching (weeks and weeks of searching) we have found the manufactures of the ARC and Velocity motors say good buy to $100.00 motors, we are going to make extreme rcing affordable to every pilot.


How to choose the right ESC (BEC, Voltages, Amps & Motor Timing)


On Board BEC or External:  For years the rule of thumb has been anything over 3s the use of a External BEC is recommended, the reason for this is that most on board BECs cannot step down voltages greater than 11.1v/13v down to a usable voltage required by the receiver to power the servos.  Some of the newer BECs however can do this but there is still a risk that if there is problem with the ESC you will lose not only engine power but also control surface response.  EDFhobbies recommends the use of an external BEC at all times and at higher voltages it is really cheap insurance.  The recommended installation area of the ext. BEC is on the deans male connector with the ESC battery wires opposite end of the ESC or away from the ESC.


Never run an ESC on higher voltages than it can handle, when the ESC gets hot it will either catch fire or shut down until it cools off.  This goes for the max amps it can handle as well.  A general but not all ways accurate way to identify a ESC max amps and Voltages are: 0 to 35A ESC is good for 12v or 11.1v lipo 40 to 50A good for 14.8v lipo or 15v, 60 to 100A 14.8v lipo to 22.2v lipo or 23v, and most 110v ESCs and higher are considerer to be HV or high voltage ESC for greater that 6s or 22.2v applications.  The HV usually never include any type of BEC, but times are changing and there are a few out there.


Motor timing is another useful tool.  Most ESCs are setup with LOW timing from the factory.  Some of the better motors can run on high timing and produce a lot more power, just be sure that your motor can handle the extra heat and amp draw that the high timing will produce.  Proper cooling for the ESC is also recommended a good rule of thumb is that the esc needs minimum 5mph of air movement to cool properly.  Ducted Fan setups are very hard on the battery, motor, and especially the esc. The quickest way to total a $500.00 jet is to cheap out on quality brand named esc and by choosing one that cannot handle the requirement of your power system.


For Example:


We recommend that you choose an ESC with at least a margin of 10 to 15amps to spare to power your setup.  So if you take for instance the Cyclone Power 2500kv motor installed in the Wemo mini 480 setup that draws around 52 to 54 amps you would choose an ESC with a minimum of 65 continuous amp draw.


Batteries:


Taking the above fan and motor combo example EDFhobbies recommends that you choose a battery a lot like the same way you choose your ESC. Give yourself some wiggle room on the amp draw.  EDFhobbies recommends at least a 20 amp draw margin. This will not only increase your battery life but will also give you some hidden power; the best way to do this is by increasing the C rating on the battery.  For Example going from the stock 20c batteries that normally comes in a RTF kit to a 35c or 45c battery.  So if the amps draw were 52 or 54 amps at wide-open throttle you would want to choose a battery that could handle 75amp constant.  Just a note that the mAh of a battery is generally recognized as for determining the duration of the flight times, (higher the mAh the longer the flight times) it is also used to calculate the continuous amp draw.  For example you take the C rating and multiply it by the mAh of the battery to get the constant amp draw the battery can handle.  So if you had a 3300mAh battery that was a 35c you would imply multiply 3300 X 35 to get 115.5 continuous amp draw.