H.A.R.M. Opel Astra Basic RTR

Radio Control Car Action, Mar 2003 by Onorato, Paul

track test

1/5-SCALE GAS

COOKIN'

with gas

IF YOU'VE JUST GOT TO HAVE THE BIGGEST, BADDEST RC CAR ON THE BLOCK, your search is over. With 23cc of gasoline-burning, 2-stroke power under its nearly 3-foot-long Opel body, the H.A.R.M. Basic 1/5 scale out-powers and out-sizes all other types of fuelpowered RC machines. Of course, you'd expect any vehicle that's s scale to be big, but you probably wouldn't expect it to be ready to run and simple to work on. The Basic is both: it arrives fully assembled and painted with an installed JR Racing XR-3 FM radio system and Hitec large-scale servos. and the 2WD chassis is very much like the IA-scale hardware you're used to-only bigger. Getting into big-time RC has never been easier, if you can stick decals onto the body and zip-tie a battery pack into the chassis. you can handle the H.A.R.M. Opel Astra Basic RTR.

KIT FEATURES

CHASSIS. The H.A.R.M.'s huge, 4mm-thick chassis plate is spacious and features radiused edges to increase its overall strength. The front and rear bulkheads are made of plastic composite with aluminum for bracing, and the radio gear and fuel tray sit between them. There isn't a radio tray, but each electronic component is securely mounted on its own plastic supports. A plastic case conceals the receiver and shields it against moisture and dirt. A large plastic bumper protects the front end.

DRIVE TRAIN. The 2WD drive train is straightforward. Its 24-tooth clutch bell is attached to a 44-tooth spur gear that's mounted on a layshaft that has a 15-tooth gear at the opposite end; here, the gear meshes with a 50tooth diff gear. The diff is a large bevel-gear unit with an aluminum housing that takes up most of the room between the bulkhead. The diff gear is so large that it pokes out through the bottom of the chassis, but the car's extra ride height should prevent the gear from bottoming out. Steel dogbones connect the diff and transfer the power to the wheels, and a complete set of ball bearings is standard.

A vital component of the drive train is the braking system. I was a little surprised that H.A.R.M. employs just one brake disc to stop such a heavy car; testing will reveal its capability. The fiber-disc brake is keyed to the diff with cam-activated steel calipers.

ENGINE AND ACCESSORIES. The biggest difference between a 1/5-scale vehicle and other engine-powered RC cars is the powerplant. These big cars use 2-stroke gasoline engines like those used in chain saws and weed cutters. In this case, a 23cc Solo engine with a pull-starter gets the Opel under way. A twin-needle Walbro carb with primer bulb controls the fuel flow. The carb uses a paper-element air filter so the engine breathes clean air.

The no-frills-design exhaust system uses a canister-type muffler with a cast-aluminum tube to direct the exhaust out through the bottom of the car. For improved performance and increased horsepower, a tuned pipe is available. A 500cc fuel tank with a threaded fuel cap and built-in fuel filter allows the car to run for approximately 40 minutes.

SUSPENSION AND STEERING. The suspension design is basically a giantsize version of the 1/10-scale hardware we're used to seeing. Thick, plastic, lower H-arms are used on the front and rear, and adjustable upper links allow camber to be changed. The hub carriers and steering knuckles appear to be bulletproof. An aluminum arm is used on the steering knuckle to minimize the risk of breakage where the steering linkage is attached. The steering is controlled by a 1/4-scale servo that has been fitted with dual-control arms to allow a push/pull setup for maximum turning power.

A single bellcrank is fitted with a non-adjustable spring to protect the servo in a crash, and adjustable steering links are connected to the steering knuckles.

Giant, plastic-body, oil-filled shocks and stiff springs are mounted at each corner of the chassis. They arrive assembled and oil-filled and don't require tweaking. The lower shock-mounting positions are protected because they are set inboard of the lower H-arm; if the car hits a raised structure, the shocks aren't likely to be damaged.

BODY, WHEELS AND TIRES. The H.A.R.M. RTR is offered with a choice of three factory-painted polycarbonate bodies: the Opel Astra DTM (shown here), a Mercedes-Benz CLK-DTM and a custom Ford Outlaw pickup. The body is well painted, and the windows have been left clear instead of being covered with black stickers to simulate glass. All I had to do to finish the body was to cut out the wing and apply the stickers. The Opel is modeled after a full-scale racecar sponsored by Jagermeister, but unfortunately, these were the only stickers that weren't included. I cut some out of vinyl (you can purchase adhesive-backed vinyl at sign shops).

The wheels and tires are mounted and glued for you. Good thing; the grooved, hard-compound tires are incredibly hard, and it would be a bear to mount them. The one-piece multispoke wheels are solid and capture the look of their full-size counterparts. A metal collar reinforces the area where the hub is keyed to the wheel.