Let's talk dirt. Gut-wrenching torque, high-flying jumps and fast-acting suspension, offroad vehicles guarantee heart-pounding action on almost any surface, any time, anywhere. If you're limited in your choice of available racing or bashing spots or even undecided about where you'd like to run, an off-road vehicle is the ride for you.
Offroad vehicles are powered by electric motors, two-stroke nitro engines, or two- or four-stroke gasoline engines (for larger scales.) Kits and RTR's are available for rally cars, low-slung two or four-wheel drive buggies, aggressive-handling stadium trucks, and two- and four-wheel drive monster trucks, the gigantic beasts of offroad vehicles. This article is intended as a brief introduction to the various types of offroad vehicles available, as entire books have been written on each, and new and innovative variations are entering the market every year.
Rally Cars
Rally cars are a like a hybrid of onroad and offroad vehicles. Higher centered than onroad vehicles, they have the clearance required to bash around on rough terrain but still have the sleek onroad car look and handling on pavement. The shock absorber travel is not as long as other offroad vehicles, so they aren't quite as tough in the rough as buggies, trucks or monster trucks.
Electric Powered Buggies
Electric buggies, which come in 1/10 scale models and are designed to run a 6-cell sub-C battery pack driven by a 540-sized electric motor*, were the first offroad vehicles in the radio controlled hobby. Longer suspension travel, agressive low-geared transmissions, and completely adjustable precision-engineered steering and suspension elements make these the fastest offroad vehicles in the hobby**.
Modeled after full-scale dune-buggies width wide rear tires and lightweight narrow rail-type tires up front, electric buggies are lighter than other offroad vehicles. While this accounts for their nimble speed, it also makes them more difficult to drive well. They are easily bounced off track in rough terrain and will spin out in corners much more easily if the driver is too heavy on the throttle. Anxious errors over jumps, tabletops, and moguls can send them into uncontrollable cartwheels. In the hands of an experienced driver, however, an electric buggy that has been correctly set up can easily outdistance most other offroad vehicles and float around a track like it's on rails.
Electric buggies require one servo for steering and an electronic speed control to regulate speed and provide braking, or two servos, one for steering and a second to operate a manual speed control.* Braking is performed by a complex set of signals sent to the motor to stop it and hold it stationary.* All three receive their power from the 6-cell battery pack used to power the buggy.
Electric buggies generally come with a step-down three-gear differential type transmission, a slipper clutch traction control device, oil-dampened shocks, and a full list of adjustable steering and suspension elements to correctly set up the buggy for any offroad surface.* The chassis and suspension parts come in a wide variety of innovative materials, ranging from high-impact plastics to carbon-plastic composite materials. Depending on the battery capacity, motor, and other factors, run time of a buggy can range from ten to twenty minutes. If you've got the driving skills (or the patience to learn them,) an electric buggy is the choice for you.
Electric Stadium Trucks
Take the 1/10 scale electric buggy, raise the chassis a little higher with wider and larger diameter tires, give it longer suspension arms, longer shock absorbers, a slightly lower-geared transmission to compensate for the additional weight, power it with the same 540-size electric motor and 6-cell pack, and you have an electric powered stadium truck.
Like their little brothers, electric ST's are extremely nimble and quick but the additional weight actually makes them more forgiving in corners, jumps, and on rough terrain, and less sensitive to driving errors. While electric buggies have narrow rail-type tires up front, stadium truck front tires are the same width as the rear tires. In combination with the added weight of an ST, this gives them tons more steering in corners.
Also like their buggy counterparts, stadium trucks come with a step-down transmission, slipper clutch/traction control device, fully adjustable suspension elements, and use the same electronic systems for steering, speed regulation, and braking.* Because of the larger tires, ST's usually can benefit from a higher-torque steering servo* than buggies. You can expect slightly shorter run times due to the added weight of an ST. The biggest difference between buggies and stadium trucks is they are a little slower in straightline speed due to the additional weight, but far easier to drive. This makes a stadium truck a better choice for a beginner in the hobby.
Nitro Stadium Trucks
Nitro stadium trucks are pretty much what you'd expect, the same configuration as the 1/10 scale electric stadium truck with a .12-.15 cubic inch nitro-powered engine instead of the electronics and electric motor. In most cases, a manufacturer's nitro truck has an identical steering, transmission, wheel, tire, and suspension setup and sometimes even the parts themselves are identical.
The chassis and drive gear, called a spur gear, are usually the largest differences. Because of the added weight of the engine and the heat it generates, the chassis is usually made of anodized aluminum, whereas the electric version can be plastic, fiberglas, carbon fiber, or other lightweight material. An engine clutch drives a pinioned clutchbell against a 32 pitch spur gear, under which is usually a similar slipper clutch/traction control device. There are also a few extra parts to fortify the structure of the chassis, shock tower, and transmission due to the additional torque of a nitro engine.
Unlike electric buggies and stadium trucks, two servos are required - one for the steering, and one for the throttle/brake configuration.* Additionally, the absence of the 6-cell pack that powers the electrics requires a rechargeable battery pack of 4 or 5 AA sized cells to power the servos and receiver. Most nitro stadium trucks have an actual disk brake system integrated into the throttle system for stopping power.*
The standard fuel tank usually holds 75ml (about 2.5 ounces) and depending on the conditions will last between 15-25 minutes per tank, but you can refill the tank without shutting off the engine. You can run a nitro for hours without having to stop to recharge anything.
The biggest difference between electric and nitro powered stadium trucks is that there is a lot more to learn to get your nitro-powered truck running. With electrics, you charge the batteries, put them in, and go; with nitro powered models, you need to understand how to operate and tune your engine, and there are a few more issues to maintenance than with an electric. But like most nitro owners will tell you, once you get past that there's really no sense in going back to electric!
Nitro Buggies
Nitro-powered buggies, which usually come as four-wheel-drive and in 1/8 scale (although recently, 2WD 1/10 scale buggies have hit the market,) are truly in a class of their own. With a low center of gravity like their electric counterparts, the additional weight and 4WD of an offroad nitro buggy makes it more aggressive in turns and far less prone to errors due to rough track conditons.
This also makes nitro buggies one of the easiest offroad vehicles to drive, and drive fast. The additional drive up front literally pulls the vehicle through turns and with all four wheels providing drive action, they have the most traction available to any racing class offroad vehicle.
Like 4WD onroad cars, nitro buggies have both front and rear differentials but also sometimes have the transmission in the center of the vehicle instead of the rear. The drive to the front diff can be a shaft or belt drive, and most models come with single speed transmissions.
Monster Trucks
If you think bigger is better, you can't get much bigger than monster trucks. Huge oversized chevron-pattern tires, high ground clearance, and extra long suspension arms make MT's look, drive, and climb like their full-scale counterparts. Monster trucks first appeared on the R/C scene as electric trucks; when it was apparent the huge tires and extra weight provided some power and run-time challenges, models sporting dual 540-size electric motors appeared, designed to run with two 6-cell battery packs. It was only natural that nitro versions followed, and today there are so many monster truck configurations it's really difficult to choose which one is the baddest.
Monster trucks were not initially intended for a racing class but for the backyard bashers who are thrilled by the ability to attack any terrain or climb over anything. Generally four-wheel drive, most monster trucks come with eight shocks - two at each wheel - an aluminum "ladder" type chassis, forward and reverse power, and many models are available with two-speed forward transmissions.
Don't let the high center of gravity fool you - monster trucks are every bit as fast as many other vehicles and can go where no other R/C's can go. It's not uncommon to see MT's bounce right up over track pipes that stop most R/C's in their tracks. Monster trucks are so popular that official racing classes have formed on most racing circuits.
The monster truck's roots still grow deep: if you don't plan on racing and just want the toughest R/C you can get that will eat up any terrain, jump, or climb over anything, an electric or monster truck is a great selection.
Now that you have an overview of RTR's, kits, and the various types of onroad and offroad vehicles, let's take a closer look at the two main types of power these use, electric and nitro powered R/C's. Most of the vehicles we've discussed can come with either, and deciding on electric or nitro is an important part of your choice of which vehicle to buy.
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