How To Get into Hobby RC: Short Course Trucks

‘Short Course Trucks’ are currently some of the most popular vehicles for RC racing. There are several reasons for the popularity of these designs. First of all, they replicate the full-scale short course racers that compete at outdoor tracks and stadiums all over the US. Perhaps a more significant aspect is that short course trucks are exciting to drive. Many short course designs are close adaptations of the top-tier 2-wheel-drive and 4-wheel-drive buggies that are at the cutting edge of RC off-road design.

RC short course trucks are not only for racing; they are also well suited to bashing. Their wide tires let them run on a variety of surfaces. It also helps that they have meaty bumpers and full-fendered bodies covering the tires. These help to keep the truck right side up when knocking into things like curbs and other vehicles.

The Cutback

My first short course truck is the Tower Hobbies Cutback. Although it has some race-ready features (brushless motor, full ball bearings), the Cutback is primarily meant for bashing. That works out great for me since I haven’t raced in years. That being said, the Cutback might be competitive at some local-level tracks.

This truck arrives fully assembled, with a painted body and a 2-channel 2.4GHz pistol-grip radio. I had to provide four AA batteries for the transmitter and onboard batteries to run the truck. I’ll talk more about those batteries in a bit.

Short Course Trucks are a popular aspect of RC for both racing and bashing. The vehicles emulate full-scale off-road racers.

This is a four-wheel-drive truck with three gear-type differentials, one on the front end, one on the rear end, and one on the drive shaft. The core of the chassis is a 3mm-thick aluminum plate. Attached to this plate is a nylon tub that houses the electronics and drive components. Other parts such as the suspension arms, bumpers and spur gear are made of molded nylon as well. Interestingly, all of these plastic parts are covered by a 1-year warranty with free replacement.

The Cutback includes an 80-amp Electronic Speed Control (ESC) with a built in cooling fan. This drives a 3600kV (RPM/volt) brushless motor that is longitudinally-mounted near the center of the chassis. Steering is provided by a metal-geared servo. Tower Hobbies states that both the ESC and servo are waterproof. Other than driving though a little mud and the occasional puddle, I have not tested this claim.

The Cutback includes a 3600kV brushless motor. Top speed in stock form is modest, but there are several options to spice it up.

The receiver is housed in a watertight box, while a covered channel cleanly routes all of the wires leading to/from this area. In fact, all of the wires on this truck are secured in-place with some form of clip or restraint. It makes for a clean layout.

The included transmitter is a no frills unit, but it works well. It appears to be the same radio that came with my Axial Wraith rock racer. It offers servo reversing, analog trims, and adjustable steering rate.

Velcro straps are provided to secure the battery to the left side of the chassis. So far, I have driven the Cutback with Duratrax Onyx 2S-5000mAh LiPo and Duratrax Onyx 6-cell 3000mAh NiMH batteries. Both of these packs fit in the provided battery mounting area with no issues. You could use a 7-cell NiCad/NiMH battery, but it would need to be in a “hump” configuration.

This photo illustrates the clean and simple layout of the Tower Hobbies Cutback.

Before running the Cutback for the first time, I gave it a thorough inspection to make sure everything was in order. I found that a few drops of oil had dripped on the inside of the body and the front end of the chassis. I assumed the oil had come from a leaky shock, but they all checked out fine. I never did find the source of the oil, so I cleaned it and pressed on.

Driving the Cutback

I have taken the Cutback to a handful of locations to test it on different types of terrain. So far, it has seen smooth blacktop, gravel, dirt, short grass, and rough pavement. The handling of the truck would no doubt benefit from using specific tires for each surface, but I’ve never dismounted the stock tires. I’m surprised not only by how well the tires work on all of these surfaces, but also how consistent the handling is from one surface to the next.

Part of this handling consistency is due to the low gearing of the Cutback. It has quite a lot of punch, but not much top-end speed. So you never get going fast enough to really push the handling limits of the truck. That’s not to say that the truck isn’t speedy…it’s pretty spunky by my standards, but race-tuned trucks would probably leave it in a cloud of dust.

The Cutback performs well on many different types of terrain, even without changing the tires.

My opinion of the Cutback’s speed is based on using the stock gearing and the batteries mentioned above (6-cell NiMH, 2-cell LiPo). The kit includes a smaller spur gear which can be swapped in to add some speed (at the cost of acceleration). Also, the stock electronics can be used with a 3-cell LiPo battery, which should really pep things up.

I may try one or both of those speed options at some point, but I’m happy with the stock setup for now. It’s plenty fast enough for the front yard/street driving I normally do. Plus, the low gearing provides run times over 20 minutes with the 2S-5000mAh LiPo.

Using the stock suspension setup, the Cutback tends to oversteer. It actually holds a line better when you stay on the power and let the front wheels pull it through. With some practice I was able to drift the truck through fast sweeping turns (except on grass).

I played with the variable steering rate adjustment on the radio. It can be set to the point where there is almost no steering at all. That’s no fun, but I found that toning down the steering throw a little below maximum helped to mitigate the oversteer issues.

The only part of the Cutback’s handling that I didn’t like was its tendency to nose over during jumps. You can sometimes control the “flying” attitude of a 4WD car with the throttle (more throttle makes the front end come up), but that technique had little effect here. The result was that anything more than a small jump often caused the Cutback to land on its front end–sometimes even tumbling. Perhaps this trait and the truck’s oversteer are signs that the balance point should be moved rearward. I don’t see many options for relocating components to redistribute the weight, but I may experiment with it.

The Cutback has a tendency to nose over during jumps, but it is a lot of fun to drive.

As with any RC or full-scale car, you can make adjustments to alter the handling of the Cutback. This could involve changing any number of parameters (shock springs, shock oil, shock pistons, weight distribution, suspension geometry, etc) to get the response you are looking for. When I was into racing, exploring the effects of these changes was all part of the fun for me. Now as a basher, I rarely take the time for suspension tuning.

The Cutback is somewhat limited in adjustment due to the molded, fixed-length steering rods and camber links (meaning toe-in and camber are not adjustable unless the stock parts are replaced). Again, I don’t miss these adjustments. In fact, I rather appreciate the durability and simplicity of the molded links. If you plan to race the Cutback, however, you’ll probably want to upgrade those parts.

I noticed a funny thing while running the stock tires on pavement. When doing donuts or slamming on the brakes, they make squealing sounds just like the tires on full-scale car, only not nearly as loud.

A possible concern was the interface between the pinion and spur gear being exposed to the elements. Since I was driving in areas with lots of small, loose rocks, I figured that it was only a matter of time before one got stuck between the gears. Well, that hasn’t happened yet. I can’t tell you how many tiny rocks I’ve dumped out of the chassis, but none have caused any type of damage.

I’ve bumped into a few immobile objects, rolled, and flipped the truck countless times. Nothing has broken yet. Even the body is still in pretty good shape. I thought that it would get creases and weak spots, but it is still holding strong and looking good. The Cutback is tough.

Final Thoughts

There’s way more to the Short Course scene than what I’ve explored so far. Even so, I’ve been very impressed by the variety of places that I can have fun with this truck. I suspect that I’ll continue to find new places to run it and develop new techniques to drive it. An off-road RC track not too far away that I recently discovered may be the perfect place to take the Cutback!

Terry spent 15 years as an engineer at the Johnson Space Center. He is now a freelance writer living in Lubbock, Texas. Visit his website at TerryDunn.org and follow Terry on Twitter: @weirdflight

SOURCE:http://www.tested.com/art/makers/528882-how-get-hobby-rc-short-course-trucks/

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