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RC Glossary


New to the RC Hobbies? What does buggy, bulkhead, nitro mean in radio control car hobbies? Check out the glossary for remote control cars below.


  • H Arm --
  • A suspension arm that resembles the letter 'H'. H arms are usually used on models that use a single (lower) suspension arm and an upper control arm or?turnbuckle, with C hubs or uprights.

  • Halls Sensor (Brushless Motor) --
  • A stationary sensor used in sensored brushless motors to detect the position of the motor.

  • Hand Wound Armature --
  • An armature that has the copper wire wrapped around the armature by a real, live person. The windings on hand wound armatures are more compact and precise than those wound by a machine, resulting in better balance and less vibration. Of course, people get paid more money than machines to wind armatures, so expect to pay more for the increase in performance.

  • Handout --
  • The motors, batteries, or tires that are given to racers in some spec races. The handouts are the same for each driver, ensuring an even playing field. The cost of handouts is usually covered in the entrance fee or donated.

  • Hard Anodized - Hard Coated --
  • An anodizing treatment that provides extra wear protection to a part. Hard anodized parts are easily distinguished by their cool, gun-metal gray color.

  • Hard Body --
  • Refers to an RC body molded from polycarbonate or styrene plastics instead of the more traditional vacuum formed lexan. Hard bodies offer superior detail compared to lexan bodies, but are more prone to cracking or damage. In addition, hard bodies tend to weigh more than lexan bodies. Still, nothing beats the detail of a hard body for scale rides, just remember to paint the outside.

  • Hard Cut Off --
  • Refers to the operation of an LVC (low voltage cut off) system. An LVC with hard cut off instantly shuts down all power to the model when the voltage threshold is reached. This, of course, stops the model dead in it's tracks. LVCs with hard cut off are commonly used for RC cars.

  • Hardwire --
  • Refers to soldering electrical connections (such as those between batteries, ESCs, and motors) instead of using plugs or connectors. This provides the least electrical resistance, but makes working on your ride a pain in the butt. There are many zero loss connectors available that makes hardwiring a thing of the past.

  • Head - (1) Nitro Engine --
  • This may be the most noticeable part of a nitro engine. The head is bolted to the top of the engine block, sealing off the combustion chamber (and keeping the piston from falling out). The head holds the glow plug, and has many fins to help dissipate heat - some may even have removable fins to fine tune engine cooling for various temperatures.

  • Head - (2) Computing Box --
  • That thing on top of your shoulders - use it when problem solving or common sense is required.

  • Head Clearance --
  • Refers to the distance between the bottom of the head and the sleeve on a nitro engine. Head clearance affects the compression of the engine, and is adjusted using head shims. If the clearance is too low (small), it may lead to detonation, or the top of the piston may actually strike the glow plug. Adjusting clearance is usually only reserved for the 'pros' looking for that millisecond on a lap times - so, unless you're racing the Nats next week, your engine is just fine.

  • Head Guard --
  • A durable, plastic part that is snapped or screwed to the top of a nitro engine's head to help protect it from damage.

  • Head Shim --
  • A thin 'washer' that fits between the head and sleeve of a nitro engine. Adding or removing shims alters the combustion pressure of the engine by changing the head clearance.

  • Header - Manifold --
  • This is the tube that runs from the exhaust port of a nitro engine to the pipe or muffler. The header is attached to the engine with either springs or bolts and is attached to the pipe with springs or a silicone coupler. Header length affects back pressure to the engine, which affects the powerband. A longer header will help the engine produce more power in the higher RPM range (to improve top speed), while a shorter header will help it produce more power in the lower RPM range (to improve acceleration). In some cases, a metal connector between the manifold and pipe may be referred as a header.

  • Header --
  • A bent piece of aluminum tubing used on Nitro cars that transfers exhaust gases from the engine case to the tuned pipe or muffler.?

  • Header Spring --
  • On some models or engines (especially for 1/8 scale buggies), the manifold is held to the engine and / or pipe with springs instead of couplers. This allows the header and pipe to 'give' during hard impacts without damaging components. Many racers 'double up' on the springs to ensure a tight fit.

  • Heat Cycle Break in (Nitro Engine) --
  • A method used to break in nitro engines. Heat cycling consists of running the engine at low speeds and rich settings at the beginning, then slowly increasing speeds and leaning the setting after each tank of fuel. This is usually done for about 5 tanks of fuel. Always follow the manufacturers recommendations for breaking in a new engine.

  • Heat Gun --
  • This is basically a hair dryer for dudes. Heat guns blow out a stream of focused hot air, and the upper end models may even have adjustable temperature settings. Heat guns are used to shrink heat shrink tubing and casings, warm large decals for easier application, and even warm nitro engines for easier cold weather starting.

  • Heat Shrink (Casing) --
  • A plastic 'envelope' that shrinks in size when heat is applied (such as with a heat gun, hair dryer, or lighter) to provide a snug fit. This casing is commonly applied to batteries, battery packs, and ESCs at the factory, but DIY types can also get the stuff for custom applications.

  • Heat Shrink (Tubing) --
  • A rubberized tubing that shrinks in size when heat is applied (such as with a heat gun, hair dryer, or lighter) to provide a snug fit. The tubing acts as insulation for exposed wire when soldering electrical connections. The tubing is slid over the wire and away from the solder joint before soldering, then once the connection is soldered and cooled, the tubing is slid over the connection and shrunk in place with heat.

  • Heat Sink --
  • A series or row of fins on a metal part that increases the surface area to improve heat dissipation. Many ESCs have a heat sink 'block', and the head on a nitro engine is basically a large heat sink. A heat sink may be available as a separate part to help cool high temp items such as motors and batteries, or it may be milled into existing parts, such as engine or motor mounts.

  • HEMI (WIND) --
  • "Refers to a way of winding the coils in an electric motor. The hemi wind results in 1/2 turns less than the actual turn rating for the motor (thus a 10T hemi wound motor is actually a 9.5T), but the resistance remains the same. This adds a little more top end power to the motor. The hemi wind is named after the Japanese """"hemi"""" slot car motor that pioneered the winding style."

  • HERTZ - Hz íV HZ --
  • A measurement of frequencies. 1 Hz = 1 cycle per second. For RC, Hz usually refers to the operating range of ESCs (drive frequency), while MHz (megahertz) and GHz (gigahertz) refers to the operating range of radio systems.

  • HEX Adapter --
  • "A hex shaped """"sleeve"""" that slides over a wheel hex to increase the size, allowing the use of rims designed for larger wheel hexes."

  • HEX Driver --
  • A tool resembling a common screwdriver, but the tip of the shaft is ground to a 6 sided (hexagonal) shape. Hex drivers are the Ferrari's of the allen wrench - often available with hard ground replaceable shafts, machined alloy handles, and neat-o keen anodizing. Get some and save your fingers some pain.

  • HEX Head --
  • A screw that uses a 6 sided (hexagonal) indentation in the head for the tool to fit into. A hex head screw requires a hex driver or allen wrench of the appropriate size to tighten or loosen the screw. Hex head screws are less likely to strip out than the more common phillips head screw. Hex heads are a common RC upgrade, and sets are usually available in exotic materials (such as aluminum or titanium) for most popular models. The most common sizes of RC hex head screws are: (STANDARD) 1/16, 5/64, 3/32 - (METRIC) 1.5 mm, 2 mm, 2.5 mm.

  • HEX Pin --
  • See AXLE PIN

  • HEX íV Wheel HEX --
  • A 6 sided adapter used to key the rim to the axle on many models (especially monster trucks, truggies, and 1:8 buggies). The hex is keyed to the axle pin with a slot on the back, and a hex shaped recess in the rim is keyed to the hex - the whole thing is held together with the wheel nut. Rims are available in various hex sizes, with the most popular being 10 mm (sedan size), 14mm (maxx size), 17mm, 23mm, and 27mm (for 1:8 buggies and truggies).

  • High Speed Needle Valve - HSN --
  • The high speed needle valve regulates the amount of fuel that enters the carb of a nitro engine at high speeds (RPM). This is the tall needle valve located on the carb. Rotating the needle valve clockwise lets in less fuel (leans the air / fuel mixture), while turning the needle valve counter-clockwise lets in more fuel (richens the air / fuel mixture). Always adjust the HSN before adjusting the low speed needle.

  • High Variance Wind - HVW - Split Wind --
  • When the coils of an electric motor are wound with 1 large diameter wire along with 1 or more smaller diameter wires, it is referred to as a high variance wind (HVW) or split wind. A split wind results in faster spool up (acceleration), but loses some top end power compared to conventional winds that use the same size diameter for all wires.

  • Hinge Pin --
  • "A straight pin of steel or titanium that allows the suspension arms to pivot in one direction. Hingepins may be held in place with E clips, setscrews, or captured mounts, depending on the model. Normally 3mm or 1/8"""" in diameter, a hinge pin can be any length."

  • Hinge Pin Insert --
  • Used with some captured hinge pin mounts, inserts are cam style 'buttons' that hold the ends of the hinge pins in place. The inserts can be rotated or replaced to alter caster and toe settings.

  • Hit --
  • "Another term for """"glitch""""."

  • Hobby Grade (RC) --
  • "When it comes to RC, the old adage of """"You get what you pay for"""" holds true. Virtually every part on hobby grade RCs can be replaced, repaired, rebuilt, tuned, modified, and upgraded - unlike the toy grade stuff you might pick up at your local Wally World, which usually becomes landfill after a few weeks. Did I mention speed, handling, and quality?"""

  • Hobby Knife - X ACTO --
  • A small, pen-like knife with interchangeable blades. These knives are used for everything from trimming flash from plastic parts to trimming decals, and will inevitably be used for emergency repairs. Stock up on some ,11 blades, they're the bomb for anything from detail trimming to hack and slash work. X ACTO is a brand name commonly used to refer to hobby knives.

  • Holding Power (SERVO) --
  • Similar to torque (oz. in.), holding power is the weight a servo can hold without moving position. Holding power is usually about 3 times the torque rating (120 oz in torque = 360 oz in holding power). Holding power is a very important rating to know when choosing a steering servo for rock crawlers.

  • Hole in the Head --
  • Stick a glow plug in it.

  • Hole Shot --
  • Refers to gaining the lead at the start of the race due to faster acceleration, which puts you at the lead of the pack and out of harms way during the crashfest in turn 1. Getting the hole shot is great when all racers start at the same time (such as with staged or gate starts). but becomes less important with staggered starts.

  • Hop Up --
  • An aftermarket part that increases the durability or performance of a model.

  • Horsepower - HP --
  • During the 'olden times', horsepower referred to how many horses it took to do a job (such as pulling a stump). Today, it refers to how fast we can potentially go and how high our wheelies can be. In essence, horsepower is a measurement of potential energy (i.e. work done / time). For electrical motors, 1 HP = 745.7 watts of potential energy per second. For nitro and gas engines, 1 HP = 550 ft. lbs. per second. HP = torque x rpm / 5,252 - so even though a standard servo and a standard nitro engine may both produce around 100 oz. in. of torque, the engine spins at a much higher rpm than the servo (about 30,000 rpm compared to about 60 rpm), which gives the engine that much more HP.

  • HSN --
  • Abbreviation for High Speed Needle Valve

  • Hub Carrier --
  • Also called uprights, these are the parts of the suspension that hold the axles and bearings the wheels of the car turn on.

  • Hump Pack --
  • A receiver battery pack that has been assembled with the cells stacked in a 'chopped off pyramid' style, resembling a 'hump', with at least 1 cell on top of the other cells. The most common hump pack is a 5 cell receiver pack with 3 cells on bottom and 2 cells on top. Hump packs are designed to fit in the tight confines of the battery boxes on most 2WD nitro stadium trucks.

  • HVW --
  • Abbreviation for High Variance Wind

  • Hydra Lock íV Hydraulic Lock --
  • This is what happens when a nitro engine becomes flooded with excess fuel. The fuel prevents the piston from reaching TDC, which 'locks up' the engine - preventing it from turning over. To clear a hydra locked engine: remove the glow plug, turn the engine upside down and crank it over a few times until all the excess fuel has drained out, replace the glow plug, then try starting the engine again without priming.

  • Hz --
  • Abbreviation for HERTZ

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