Shopping Tips 101
Speed Control Shopping Tips
Brushed/Brushless: An ESC and motor must match: Brushed motors need brushed ESCs. Brushless motors need brushless ESCs.
LiPo Batteries: If you use LiPo packs, you need a LiPo-compatible ESC. (These ESCs are also compatible with NiCd and NiMHs.)
On-Resistance: Lower numbers mean more efficiency and better performance overall.
Motor Limit: The "hottest" motor the ESC can handle. More turns (T) are okay.
Size/Weight: Smaller ESCs are easier to install, especially on 1/18 or 1/20 scale chassis. Less weight = more efficiency and power.
Price: Sport (fun) ESCs are the lowest in price. ESCs that offer more programmability and/or racing features tend to increase it.
Types: Forward-only or forward brake ESCs may be for sport or competition, depending on price. ESCs with Reverse are primarily for sport, but may include reverse lockout (disable) to make them race legal.
Battery Shopping Tips
Capacity: How much energy a cell can store. Capacities range from 50mAh (milliAmp hours) to 5400mAh.
Cell Set: A package of unassembled cells. Great for do-it-yourself types. More economical than prebuilt packs.
Configuration: How cells are assembled. Cells are end-to-end (in stick packs), side-to-side (in flat packs) and split into two side-by-side groups (in saddle packs). In hump packs, at least one cell is stacked on other cells.
LiPo, LiIon: While newer, lighter and more powerful than NiCd or NiMH cells, Lithium-Polymer (LiPo) and Lithium-Ion (LiIon) cells also cost more and require special chargers.
Matched Cells: Cells discharged at a specific (amp) rate and matched to others with similar run times and average voltages. Many are also processed to boost voltage. Most command a premium price.
NiCd (Nickel-Cadmium): The most common and economical type of battery. See NiMH, LiPo/LiIon.
NiMH (Nickel-Metal Hydride): About the same size and weight as NiCd cells, NiMH cells cost more but offer a wider (and higher) range of capacities. NiMHs are also more environmentally friendly, and require neither cycling or recycling.
Pack: A set of assembled, shrink-wrapped cells that includes a lead (wires) and connector. Packs cost a bit more than cell sets, but can be used immediately.
Sub-C Cells: Slightly smaller than typical "C" cells.
Voltage (V): A measure of force. Nominal voltage of a LiPo cell is 3.7V, vs. 1.2V for a NiCd or NiMH cell. More cells = more voltage = quicker acceleration!
Charger Shopping Tips
AC vs. DC: AC units plug into 110V home outlets. DC units require a 12V battery or power supply. AC/DC units can use both, so you can charge anywhere!
Capacity: How much energy a cell can store, in milliamp-hours (mAh).
Capacity, Charger: How many cells can be charged. May be expressed as a range of cell capacities (100-1,300mAh), voltages (1.2-9.6V) or cells (1-8).
Discharging: Draining energy from a cell or battery pack. Regular discharging conditions cells to perform better and last longer.
Fixed vs. Adjustable: Current Fixed chargers have only one charge rate. Chargers with adjustable rates allow you to tailor the rate to the battery capacity.
Lead-Acid/LiPo/NiCd/NiMH Battery types: A charger may be suitable for only one type of battery or all four. Be sure your battery and charger are compatible.
Timed vs. Peak: Timed units charge until time runs out. Peak units charge until the battery is fully charged and automatically turn off to prevent overcharging.
Air Radio Shopping Tips
ATV: Adjustable Travel Volume. Also referred to as end point adjustment, ATV lets you preset the maximum travel of a servo to either side of neutral. Allows you to tailor control outputs to your flying style.
Dual Rates: A two-position switch on your transmitter that makes the controls more or less sensitive. The lower rate is good for beginners who tend to overcontrol their models.
Exponential Rate: Offers servo travel that is not directly proportional to stick travel. Control response is milder below half-stick, but becomes increasingly stronger as stick travel approaches 100%. Great for aerobatics and trouble situations.
Mixing: Allows simultaneous operation of two or more channels from a single control input. A feature for intermediate-advanced fliers, which simplifies routine flying operations and makes more involved maneuvers possible.
Programmable: Refers to computer radios. Allows flight settings for different planes or types of craft to be electronically input and stored in memory for future use.
Servo Reversing: Allows you to change the direction of servo rotation by flipping a switch. Eases servo mounting and increases assembly flexibility.
Trainer System: Allows instructor to link his/her radio to a student's radio via a cord, and to take control of student's craft in-flight by flipping a switch.
Surface Radio Shopping Tips
ESC/Electronic Speed Controls: Unlike manual servo-operated speed controls, ESCs reduce speed-robbing weight and extend run times.
ATV/Adjustable Travel Volume: Also referred to as end point adjustment, ATV lets you preset the maximum travel of a servo either side of neutral. This allows a racer to shorten or lengthen their cars steering and throttle ranges to suit their own driving style
Servo Reversing: Allows you to change the direction your servo rotates by the flip of a switch. A nice feature that can save you the frustration of having your servo turn the wrong way.
Dual Rates: A feature on your transmitter that makes the controls more or less sensitive. The lower rate is good for beginners who tend to oversteer their model.
DSC/Direct Servo Control: DSC allows you to operate the servos in your system without transmitting frequency. This is ideal for pit checking your radio setup while others are operating on the same frequency.
Rechargable/Dry Batteries: Some advanced radio systems come with rechargeable batteries for your convenience. Others require "AA" batteries and must be supplied by the modeler. All rechargeable systems also include the proper wall charger (110VAC).
Servo Shopping Tips
Analog Servos: Lowest in cost, best for sport.
Digital Servos: Superior to analogs in speed, precision, smoothness, centering, holding power and dependability Downsides: higher cost, greater energy needs.
Size: How well does it fit? Modifications are possible, but may affect performance.
Ball Bearings (BB): Help servos last longer and run smoother and faster than bushing servos
Gears: Molded gears cost less. Metal gears are stronger and more dependable, but may cause interference.
Torque: Read "muscle." Does the servo have the power you need?
Brushless Servos: 30% faster than brushed digital servos, with five times more service life.
Programmable/S.Bus Servos: Allows programming of most (or all) parameters for truly custom performance.
Transit Time: Read "response time." Slower servos are more forgiving; faster servos excel at swift, strong response.
Coreless (Motor): Improves resolution for smoother operation (than cored motors).
Weight: Lighter is better. Added weight drains packs faster and can affect balance and handling.