Bringing Realistic Racing Action to Small Scale RC
RC racing has most of the fun of full-scale racing without all the dangers, expenses, and hassles. There are a lot of similarities in the racing lines and car setup strategies. But there are a few fun aspects of full-scale racing that are not as prevalent in on-road RC racing:
Close Battles: If we compare RC racing to full-scale racing, it's plain to see that RC racing in general tends to be a lot more hyperactive. To some degree, this adds to the excitement, but it has some drawbacks as well. Compared to full-scale racing, even the most skilled RC drivers are less often able to race side-by-side and bumper-to-bumper, because everything is happening so fast. How could we bring more of the predictability and precise control that exists in full-scale cars into RC, to promote closer and longer battles?
Braking: In full-scale racing, braking points, braking zones, trail braking and braking battles are a big part of the game. The most common place to pass is on the brakes while slowing for a turn. Some of the most intense moments in full-scale racing happen in the braking zones. How could we get more of this in RC?
Dips and Rises: Most full-scale road courses have elevation changes - ups, downs, dips and rises. The rises cause the cars to "get light" and drift towards the outside of the turns, and the dips give the cars higher traction that the drivers must take advantage of. Harnois Race Park has seamless dips and rises in the middle of turns, and the effect is quite fun!
Suspensful Sliding: Full-scale cars can slide out-of-control for an extended period of time. Sometimes they'll oversteer and run off into the grass on the inside of the turn. Other times they'll spin or push and slide off the outside of the turn. And other times the driver is able to recover the slide and suffers only some loss of speed. In high-traction RC racing, especially small-scale, when the cars slide sideways, they usually either immediately stop, or they "traction roll." This difference exists mainly because full-scale cars have a lot more momentum than RC cars, but could we get more of this suspenseful sliding sensation in RC?
The Finish Line: In some RC racing, the sensation of driving hard out of the last turn on the last lap and sprinting to the finish line to win by a wheel is lost. The end of timed heats can be rather anti-climactic. What is racing without a sprint to the finish line?
For 5 years now, we have been experimenting with track designs, car setup rules, and racing formats, striving to create an RC racing environment that better incorporates these aspects of full-scale racing. The Harnois Racing Formula DVD demonstrates success quite clearly, but we have a never ending string of ideas to take it even further!
Isn't this supposed to be "for fun?" So why have so many rules? Every sport in the world has rules that define that sport. Without something to define the game you are playing, there is no game, no challenge, and no fun. Even two guys playing one-on-one basketball have rules - they don't punch or tackle each other, or climb up the pole to force the ball through the hoop, or run down the street and put the ball in a different hoop. With no rules, and no track, what are you left with? Driving your RC car or truck back and forth outside in the street or yard with no particular goal or skill involved will get boring in about 5 minutes for most adults. If all the racers have different vehicles with different capabilities, there won't be much of a race. Given how variable and technical RC vehicles have become, it does take some very specific rules to get everyone in the same frame of mind and create a realistic and super fun racing event. We aim to bring all the challenges of full scale car racing into RC, so we can have all the fun of racing without the dangers and expenses. And it's most fun when you have more and better drivers, so we aim to encourage new drivers and help all of us become better drivers. And we don't want to have to continually spend more money and time developing the cars in order to keep up with each other - we just want to have good cars and race.
The Formula Harnois concept is all about promoting a style of RC racing that involves the closest, most intense, and most realistic battles possible in RC. The basic concept is to combine a realistically-proportioned track, realistically-powered cars, somewhat lower traction levels, and a more exciting racing format, to produce a more realistic, competitive, and exciting style of racing. Many more aspects of full scale racing come into play in this type of racing, such as braking zones and deliberate passing maneuvers. There are basically 4 components that make this realistic racing possible: Car configuration, track design, the racing format, and driver mentality. Each of these are discussed in detail below. One other important aspect is driver skill. You'll never have realistic racing with a bunch of sloppy drivers, but with the right car configuration, track design, race format, and driver mentality, drivers can drastically improve their learning curve and get a lot of practice with a good car in a good environment.
Car Configuration: The cars should have a realistic scale speed. All the cars should have equal levels of power and traction, but there should still be allowances for individual driver setup preferences and general car quality improvements. The cars should have a level of power that is appropriate for the size of the track and the traction level, so that the drivers will not be out of control with too much power. Since there will be a lot of cars racing very close together, all the cars must be stable, consistent, smooth, accurate, and predictable in order for this type of racing to work. This is all about close racing action and having cars that are too fast, out-of-control, or mismatched takes away from the fun for everyone because it causes people to get knocked out of the race or held up and taken out of the pack. With less speed there is also less speed differential between the cars, which means they can bump and nudge there way past each other while still staying in the battle. The cars are still very fast relative to the size of the track. A lot of skilled use of the brakes is required to do well. Although the concept can be applied to many types of RC racing vehicles, we use 1/18th scale vehicles because they have most of the driving quality of larger cars but are small enough to race on a tight indoor track. We use on-road vehicles because they require less space and they have smoother more predictable handling which promotes closer racing. And we prefer open-wheel cars because the impact physics are much more realistic and interesting (and downright hilarious).
Track Design: The track should be realistically proportioned, which means it will be narrower than usual with lots of curves. It should also incorporate realistic features such as rough runoff areas and sloped barriers that promote much smoother racing as compared to walled-in tracks. Our 1/18th scale track is only 22 to 28 inches wide, much narrower than usual for the type of car we are using. This more proportional scale lane width means that passing requires a lot more skill and strategy similar to full scale racing, and there is more battling for position amongst multiple cars. This may seem impossibly narrow, but because the cars also have a realistic speed, this realistic lane width actually works quite well, and allows for a more intricate track in any given size area. The smooth surface and spec foam tires provide a medium level of traction. The tighter track combined with medium traction levels reduces speeds and promotes smoother, more realistic, and more predicable lines, and improved driver reflexes, which allows the drivers and cars to race much closer together.
The Racing Format: The race format promotes driver interaction by putting all drivers on the track simultaneously, repeatedly starting the faster drivers behind the slower drivers, and running a large number of short races. The cars are regrouped every few laps creating many more opportunities for battles and close finishes. The best drivers will not be able to simply jump out front and run a bunch of fast laps, they'll have to weave through the pack every time. The newer drivers will get many opportunities to win, starting at the front of the grid. There being so many races creates the effect of an endurance race. Usually over 200 laps are completed by all drivers in each event. Lots of driving time speeds up the drivers' learning curves, and better driving overall leads to better racing. Every position in every race counts towards the final event score. Consistent smooth driving, tight lines, passing technique, race strategy, dealing with heavy traffic, and avoiding the pileups are the most important skills. This "sprint racing" format also means that there is no need for turn marshals interfering with the race. It is part of this racing that once you are flipped or stuck you DNF in that race. This encourages more careful realistic driving. You also don't need a timing system. More info about our Racing format is on the Results Page.
Driver Mentality: Drivers should work together to get all the cars working smoothly and having equal power and smooth handling, because this leads to the most exciting racing. It is not within the spirit of this style of racing to try to find loopholes in the rules to find more power or traction than the other drivers. But, drivers are encouraged to develop the cars for the sake of creating smoother, more predictable, or more accurate handling, and to pass those developments on to the other drivers. This is a considerable deviation from the usual racer's attitude, who is naturally trying to find ways to get more power and handling than the opponents. But in some friendly local racing, what's the point of trying to outdo your few opponents with more power and car setup? If you are just going to leave them in the dust without a challenge you might as well race by yourself. And you just might be racing by yourself if you don't encourage and help out the beginners so they can become better drivers. Beginners unable to understand the bizarre behaviors of their ill-handling cars will have a very difficult time improving their driving skills. Besides, the drivers who are always thinking they're going to win the race with power are typically the ones running everyone else off the track, and if you knock everyone else out of the race, then there's no longer a race! As soon as one car crashes, that's one less car in the race, and that much less competition and fun. Drivers should try not to crash into their opponents or run them off the track. The hilarious crashes will happen anyway, despite everyone's bets efforts to avoid them!
Formula Harnois - Specific Rules for Racing at Harnois Race Park
The following specific rules are designed to apply the Formula Harnois Concept to our specific racing environment. We encourage you to use this as a template to create your own rules for whatever kind of vehicle you want to use on whatever kind of track you have.
New Drivers, don't sweat all these details. You do not have to immediately have a car that meets these rules in order to race, just something kinda close. We will help you over time get your car in shape.
Car Model: All of our regular drivers are currently using the Xray M18 Standard, and this is strongly recommended. The HPI Micro RS4 also works but this car has been discontinued. The Xray M18 Pro or Xray Pro Lipo would probably also work, but we haven't tested it. Other 1/18th scale on-road vehicles may also work, but we do not have any experience with those vehicles yet, and there may be difficulties in making them match in performance, traction, and weight. Other possibilities include the Duratrax Vendetta TC, Robitronics Scalpel, and BRP SC18. Larger vehicles such as the RC18R are not compatible.
Equal Power: At the beginning of each event, the cars will be calibrated if necessary. This is done by drag racing the cars in pairs for the entire length of the longest straightaway on the track. The drivers should adjust their throttle end points until all the cars are about equal, with some give and take to account for differences such as gear ratio. If a driver needs to switch batteries, his car should be recalibrated if necessary. Any car should be recalibrated at any point during the racing event if it appears necessary.
Equal Power Alternate: All drivers are encouraged to use a transmitter that has an adjustable throttle end point setting to allow for calibration. Drivers who do not have a transmitter with that feature must use a battery and motor that gives the car an appropriate level of power for the track being used that day. Then the other drivers can calibrate to that speed. 1/18th scale cars can race on tracks with a wide variety of proportions and traction levels. Bigger tracks with higher traction require more power and smaller tracks or less traction may require very little power for good racing. For Harnois Race Park, because it is so tight and low traction, 4 AA rechargeable batteries and an unmodified 180 brushed motor is enough.
Motor and Batteries: As long as the transmitter has a throttle end point setting to allow for calibration, any motor or battery type can be used. However, when racing on Harnois Race Park as we typically do, which is very tight and low traction, very little power is required so just about anything will do.
Speed Control (ESC): Any speed control designed for racing that has a braking feature separate from reverse can be used. An option to spearately control reverse power is strongly preferred. In a lot of RC car racing, reverse is not allowed because it is disruptive. We prefer to allow reverse but only at a very slow speed as a compromise. A smooth braking feature is absolutely necessary.
Tires: Xray brand HARD FRONT and SOFT REAR pre-mounted foam only. No traction compounds or other tire treatments of any kind. Do not store the tires in a plastic bag with moisture. Do not apply traction compound. Do not apply CA glue to the edges. Nobody wants that kind of hassle here. The tires can and should be reused for many months. Tires are occasionally bulk ordered for the whole group so all drivers receive new tires at the same time. The slide-on style pre-mounted foam tires sold for the Xray M18 Standard also fit the HPI Micro RS4.
Transmitter/Receiver: Regular drivers will need a transmitter with adjustable throttle end point for the purpose of power calibration. In general, we strongly recommend a name-brand 2.4 GHz system with the following adjustments: steering exponential (aka arc); throttle, brake, and steering end points. The car's antennae should be kept inside the body unless this creates a reception problem.
Upgrade Parts: Only parts that are available to all drivers at a reasonable cost may be used.
Custom Parts: Any custom fabricated parts must be made available, with a reasonable amount of money, effort, and time, to any other driver who wishes to have that part. Custom parts may be developed for the purpose of making the cars more reliable, durable, accurate, smoother, etc.
Body: We prefer that everyone use open-wheel bodies, because the crash physics are just more fun and this keeps it equal, but any body can be used. Make it look good!
Dimensions: Car weight, as driven, must be between 390 and 420 grams (except for a car carrying a camera). The weight requirement is to keep the collision physics equal. Stock width must be maintained. Wheel base can be adjusted between 145mm and 170mm (stock is ~150mm). Do not install any parts that protrude far out the front or back of the car.
Car Condition: The car should be reliable and durable enough to go the whole event without having to stop consistently for time-consuming repairs - we want all the racers in the race as much as possible! To meet that description, a servo saver is almost certainly required. The car should have stable, accurate, smooth, and predictable handling. A high quality servo (HS-81 or better) is required. The car should not veer left or right due to acceleration or brakes. It should turn left and right with equal ability. It should make turns without suddenly spinning out. It should be able to turn sharp enough to actually make the turns. It should have predictable delivery of power and brakes. The suspension and steering should operate free of friction. The bearings and all other drive train parts should be in good shape so as not to cause unpredictable handling problems. The differentials should function smoothly and properly. The steering linkage screws and all other screws should be tight. The steering should consistently return to center - it should be able to consistently go straight down the straightaway! If a car is malfunctioning, spinning out suddenly, unable to track straight, or any other handling problem that disrupts the racing, it should be removed from the racing until fixed. But no worries, we'll help you fix it, whatever is wrong with it!
No Nonsense: No devices intended to give the car an unfair traction or power advantage. No aerodynamic downforce, including fans or wings or anything else, except for small wings typically used for aesthetic purposes. Only front tires can be mounted on the front, and only rear tires can be mounted on the rear. No 4 wheel steering. No weapons - this is not battle bots. All chassis adjustments must be symmetrical. Bottom line is aim to keep the cars equal in power and traction and enjoy racing. However, experiments to improving the the cars' stability, accuracy, smoothness, and predictability are encouraged.
Allowed Adjustments & Setup: Front and rear toe, front caster, front and rear differential tension, weight bias, gear ratio, ride height (preload and top-out-screws), spring stiffness, steering end points, braking end point (braking power), steering and throttle exponential (aka arc), and possibly other adjustments can be made. The lower chassis plate can be the stock composite, carbon fiber, or other. The upper chassis can be stock, carbon fiber, other, or removed altogether. Adjustable tie rods can be added for toe adjustment. 4 wheel brakes are required, which means one-way differentials can not be used, but otherwise, any differential may be used. Weight can be added to the car to adjust weight bias as long as the overall weight is within the specified range. Any spur and pinion gear combination may be used. Aftermarket springs and shocks may be used.
Formula Harnois - Adapting the rules for your track or type of vehicle
Our specific rules are for 1/18th scale on-road cars on our very unique track. This section suggests how you could use our rules as a template, adjust them to suit other tracks or types of vehicles, and still maintain the general Formula Harnois concept to promote super close and realistic racing.
Keep the Equal Power rule if possible. This does require that everyone has a transmitter with adjustable throttle end point. Alternatively, the vehicles can be made equal by specifying the battery type, motor type, and ESC, but there always seems to be differences anyway, and this takes more organization which can be difficult. Plus, using the throttle end point allows you to fine tune the speed of all the cars to suit the size of track that you are using on any given day.
Adjust your battery, motor, speed control, and/or throttle end points to make the speed of the cars appropriate for the size of the track and the traction level. If you can drive around the track on-throttle almost the whole way around, the car is too slow. In this case, make the cars faster, or better yet, make the track narrower and add more sharp turns (which will also make it longer!). If you can only hold the throttle on for a split second at a time without running off the track, the car is too fast. Too much power will result in sloppy, silly, and unrealistic racing. Ideally the car should have a level of power that makes it possible to hold the throttle full on for one or two seconds or more on one or more straights, but also requires braking or at least letting off the throttle to make the turns. 4wd cars should not have consistent problems with spinning out on throttle. This evaluation should be done by the more experienced drivers, but err on the side of making the cars slower as this will make for much smoother racing, and be more enjoyable for beginners.
The racing format suggests doing 3-lap races. For longer tracks, you could use fewer laps. Adjust the number of races you do depending on how much time you have.
Use lower traction surfaces if you can find them. RC cars are so hyperactive compared to full scale cars. Things are happening so fast that no RC car driver can react the way real car drivers can react. This is just a matter of the laws of physics. Using lower traction surfaces is one very good way to offset this. It helps slow things down and provides more time for drivers to make adjustments to their line and react to other cars around them, which makes for better racing. It's tempting to think that lower traction is more difficult, but not necessarily. The trick is to set up the cars to push (understeer) rather than spin out (oversteer). This is why we specify soft rear and hard front tires, to improve stability. One squirrelly car in a close pack can take out all the other cars and ruin an otherwise great race. Get very specific with the tire rule so that everyone is driving with the same amount of traction. The other trick to racing on lower traction surfaces is to agree to keep the power down to a controllable level to minimize sliding and maximizie controllability.
Recommended Setup for Xray M18 on Harnois Race Park
Use the composite chassis and no upper chassis plate, for maximum flexibility for smooth handling. Get the adjustable tie rods and set front and rear toe to near zero, otherwise the car will wonder around on the straightaway (not track straight). Use the 6-degree front caster A-arms for more responsive steering. Use the stock differentials with no tension to minimize unpredictable sliding. Set weight bias towards the back by mounting the batteries as far back as possible, for the best front-to-rear traction balance. Use the stock spur gear and the 17-tooth pinion. Use our CNC-machined carbon fiber leaf springs for friction-free suspension and steering movement, and set the ride height to be about 1/8-inch after the car "droops" or "sags" under its own weight. Reduce the brake end point as necessary (usually set it at around 70%) to prevent brake locking. Use a very high exponential arc setting (70-90%) for accurate straightaway corrections. Set the steering end points as far as the chassis mechanically allows, but reduce the end points or "dual rate" if the steering is too sensitive. See the Cars Page for pictures.