Here are some more advanced topics about motors. Learn how to get the fastest motor for your specific racing needs.
Big "Comm" versus Small "Comm"
In general, big commutators provide more torque while the regular size commutator provide more rpms.
Big comms - High load, high current applications. Off-road racing.
Small comms - High rpms, lower current applications. On-road racing.
Number of Turns
Refers to how many times the copper wire is wound around each pole of the armature. Basic guide:
More Turns (e.g. 19T) = Higher torque, less rpm, longer battery life. Slower but easier to drive.
Less Turns (e.g. 12T) = Less torque, more rpm, shorter battery life. Faster but more difficult to drive.
Number of Winds
Besides the number of turns, the number of winds refer to the number of wires wound around the armature. Basic guide:
Single Wind = Most bottom end power. Power is achieved at lower rpms. For short racing tracks with a lot of turns.
Double / Triple / Quad = Less bottom end power. Power is achieved at higher rpms. For long racing tracks with long straights.
Comm Drops
Usually designed to increase power in stock motors, and usually increases rpms. But using commutator drops would require frequent motor rebuilding. Use only a few drops before each run, and clean the motor with a high quality motor spray after each run.
Hand versus Machine Wound
The method of wrapping wires around the armature is either done by a machine or a human being.
Hand wound - More precise, more power, more expensive.
Machine wound - Less precise, less power, less expensive.
Balancing
The typical rc electric motor has 3 poles, with each pole having wires wound around it. If each pole is properly balanced (i.e. same weight), then the armature can rotate smoothly, providing maximum power.
There are two methods used to get a balanced armature. One is by removing material from the armature pole. This method will also reduce the motor's power.
The better method is to apply epoxy to balance the armatures. This is better because it will not affect the magnetic field, and not reduce power.
Heat Sinks
Heat is the major enemy, especially in electric motors. So to get the maximum power it is important to keep your motor as cool as possible. Aluminum heat sinks help dissipate heat and keep your motor cool.
Lets touch on recoil motor, a good basic method can already wind up with an estimated insane RPM of 120000, 5 times faster then a usual Plasma Dash?? Speed recorded will be at least 85km/hr +/-, comparing to plasma, only 55km/hr +/- max.. However, we wont be able to fully utilized this amount of RPM, which will drastically drop due to other factors; batteries, work load, heat and Torque.. Torque, also called moment or moment of force, is the tendency of a force to rotate an object about an axis,[1] fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist. In more basic terms, torque measures how hard something is rotated.. Torque strongly affects how long a motor can last running on a track too, higher torque gives you more endurance on the long run.. A good example can be seen *here*, even Tamiya motors are manufactured with differently for various uses.. For example, compare a atomic-tuned with a torque-tuned as below:
Atomic-Tuned:
- RPM 13700 with torque of 10 g-cm, requires 1300mAh
Torque-tuned:
- RPM 12000 with torque of 14.5 g-cm, requires 1200mAh
From that comparison, its quite obvious that Atomic-tuned can run faster on the tracks.. However, it consumes more power as compare to a Torque-tuned.. On a long tech course, its wiser to use a Torque tuned, although overall its slower by a little, survivability does makes a difference that way..
Lets move on to more facts on recoil motor mainly on this few points:
- Thicker wires, high transmission of current flow, hence higher top speed
- More coils on the rotator provides a high torque
- The stronger the magnetic field inside the motor, the higher the torque is
- High current passing through, give higher speed
- Wire thickness are between 0.35-0.65, any thinner/thicker hinders ability
- 3 different materials; expensive gold, silver, cheapest and most common copper
- Good Quality of wires can be judged: malleability, toughness
deep red color
insulation on wire not easily wear off
Important Factors while recoiling:
- Every single round have to be tighten and well spaced, if any "looseness" or gap spotted in any steps, best to restart
- The recoil pattern have to stay constant on the 3 sides of the rotator, this is to prevent too much unnecessary vibration produced
- Magnet chosen should be of the same strength, irregardless of normal or super magnet, thicker magnet tend to be closer to the rotator, hence higher torque can be achieved
- A survey done among top racers of Japan/Taiwan, thick magnet are actually too close to the rotator while its running, too much torque in fact prevents their cars' max speed from going any higher
- Racers usually choose to use thin super magnet, as its more versatile
- You might choose to use a thin and a thick magnet, or a super magnet and the other normal one
- The above method is only used on special occasions, however not recommended
- Wise to try out the same thickness of wire, recoiling different methods, or different thickness of wire on a same method of recoil for better effects
main source: http://sgmini4wd.com/forum/
