For more details see Section 30.2, “Motor selection guide” and Section 30.3, “Motor selection table” in the Chapter 30, Technical Appendix

6.4.1.21. Summary

If you choose a brushless motor, then an autorotation gear is highly recommended. Most brushless motors have extremely high torque so when the motor spools down, the "braking" effect will be very strong. This will very likely break the main gear teeth if you do not have an autorotation gear. The only exception to this is the Corona; the main gear on it is very tough and can handle a brushless motor without an autorotation gear.

The older sensored Aveox motors (12xx and 14xx series) are only rated to 20,000 rpm, and the JETI motors are only rated to 15,000 rpm. You must be careful not to exceed these rotational speeds otherwise the rotor may eject a magnet (i.e. "throw a magnet"). Therefore, I do not recommend these motors for helicopter use. The better motors such as the newer Aveox, MEGAs, Hackers are typically rated for 50k-70k rpm, which makes them a better choice for helicopter applications.

The Model Motors 2814/10 is not recommended for an ECO 8. The motor seems to have problems with the rotor wobbling and touching the stator windings which burns out both the motor and the ESC. There are also some reports that the magnets are not epoxied very well to the rotor and may shift position. Also, these motors are not very efficient, and run very, very hot when used in a helicopter.

Most of the HiMaxx motors are not very efficient and therefore are not very good for larger helicopters because they generate large amounts of heat. There was one report of an HB 3615-2100 used in an ECO 8, and it became "too hot to touch". The HiMaxx seems to work okay in microhelis such as the Hornet CP and Zoom. The choice of a motor with a proper Kv for a collective pitch helicopter is very important, because most motor ESCs are not efficient when running at much less than 90% throttle. If you run an ESC continuously at low throttle, the ESC will probably overheat. Therefore, you should select a motor + pinion combination that will allow the motor ESC to run at 90-95% throttle for best efficiency.

Pole counts for motors are unfortunately difficult to find, and are necessary to program some ESCs correctly. Here are the pole counts that I have managed to find:

• 2 pole: Hacker, Kontronik, Lehner, some Plettenberg

• 4 pole: Aveox, Neumotor, some Plettenberg

• 6 pole: Mega 16 and 22 series, some Plettenberg

Also see Tohru Shimizu's helicopter brushless motor page at: www.dokidoki.ne.jp/home2/tohrus/motorindexE.html

	Note
	Check the length of your motor mounting screws before mounting! If they go too deep into the motor they will short out a winding which will damage the motor. Even worse, if you try to run a motor with a shorted winding, it will burn out the ESC. So test the screw length by screwing it into the motor with your fingers before mounting in the frame.

For more details see Section 30.4, “Pinion selection guide” in Chapter 31, Glossary

Most helicopter manufacturers supply a range of pinions for their helicopters. You may require pinions with more teeth for some reason. The most common reason is for running outrunner motors which usually have a fairly low Kv and therefore require a pinion with a higher tooth count.

Some helicopters use metric pinions, and some use English pinions.

The smaller brass press-on pinions (1 and 1.5mm) can be very difficult to remove from motors. I do not recommend the GWS pinion puller for these - I have personally destroyed two GWS pinion pullers trying to remove this type of pinion. The Maxx products pinion puller (ACC650) is much sturdier than the GWS pinion puller. Also, many brass pinions can be pulled off motor shafts by using heat since brass has a high coefficient of thermal expansion.

The best way to remove these brass pinions is to clamp the motor in a vise, then press a hot blunt tip soldering iron on the end of the pinion (for maximum heat transfer), wait about four seconds to allow the pinion to become hot and expand, then pry off the pinion using needle nose pliers. Do not skip the soldering iron step, because otherwise you will pull the shaft out of the motor.

The best way to install a brass pinion on a motor is to use a vise. Put the motor and pinion between the jaws, and screw the vise shut to push the pinion onto the shaft. Be sure the back end of the shaft is pressed against the jaw otherwise you may damage the motor bearings.

When selecting pinions, be sure to check your helicopter manufacturer's pinions first. The pinions from the helicopter manufacturer usually work best for most models.

The standard connector for nonmicro helis is the 3.5mm bullet-style connector. These work well for up to 70 amps and are supplied with Schulze controllers.

For the main motor of FP micro helicopters and for tail rotors of micro helicopters, the most commonly used connector is the crimp pin from a D-sub connector. These are good up to about 4 amps and are available from Jameco Electronics; the female pins are part #43369 and the males are part #43377

For the main motor of CP micro helicopters there really is no standard. I personally use the MP Jet 1.8mm gold connectors, which are available from Aircraft World.

(See Chapter 31, Glossary for a definition of ESC)

If you plan to use a brushed motor, you will need a brushed motor ESC. If you plan to use a sensored brushless motor (like the X-250-4H) then you can use either a sensorless or sensored brushless motor controller. For the sensorless brushless motor controller, the sensor wires (connector) from the motor will not be connected to anything because the sensors are not required by the controller.

The sensored brushless motors may need to be sent back to the motor factory to reverse the motor direction if your rotor head is spinning in the wrong direction. Therefore, I recommend avoiding sensored brushless motors unless you already know the timing is for the desired direction of rotation.

If you plan to use a sensorless brushless motor, you will need a sensorless brushless motor controller. This motor type is not usable with a sensored brushless motor controller (such as the older Schulze Booster-40b).

An ESC used for main motor control must have the following characteristics are required (or must be programmable):

Most airplane ESCs are not suitable for helicopters because they have low throttle resolution, include a brake and have a fairly high low-voltage cutoff.

For the micro helis, the following are poular as main motor ESCs:

For the Corona, the following work:

For the ECO 8/16, the following work:

For the Logo 10, the following work:

Do not use the SMILE 40-6-18 in the Logo 10 - it tends to burn out!!!

The Hacker Masters seem to burn out in the Logo 10 as well due to ESD problems.

The JETI Micoprocessor (red label series) is not suitable for helis because the throttle control is not smooth and is rather "steppy". The Advance (blue label series) is supposedly better, but nobody I know has tried this.

Some ESCs have an optocoupler (usually called OPTO) instead of a BEC. The optocoupler electrically isolates the ESC from the control signal which reduces the possibility of interference from the external BEC.

The Kontronik ESCs have a good soft start and governor mode for use on helicopters. However, they do not have thermal overload protection.

The Schulze ESCs also have a good soft start and governor mode, and they do have thermal overload protection.

The Castle Creations Phoenix works fine in the Piccolos and the Corona but does not work well in the ECO 8/Logo 10 and larger helis. The current version of the firmware has a problem in three areas:

Therefore, the Phoenix is not suitable for larger helicopters until these firmware bugs are fixed.

If you are mounting the Phoenix ESC with double-stick tape, be sure to put the tape on the BEC side and not the FET side. The FET side generates the most heat, so it needs to be exposed to free air.

Phoenix 35 ESC showing the BEC side

The FET side is the side with the regular pattern of identical chips. The BEC side has a random collection of chips. Do NOT use a switch between the battery and ESC. Most switches will not handle the current and will become very hot. Also, if the battery is plugged into the helicopter, you should consider it live for basic safety reasons anyway.

(See Chapter 31, Glossary for a definition of ESC)

You will only need a tail motor ESC if the heli has a tail motor, obviously.

For the tail motor ESC, two characteristics are important: