Radio-controlled cars operate at the same frequency. How to set up an RC car? Sequence of changes

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How to set up an RC car?

Model tuning is needed not only to show the fastest laps. For most people, this is absolutely unnecessary. But, even for driving around a summer cottage, it would be nice to have good and intelligible handling so that the model obeys you perfectly on the track. This article is the foundation on the path to understanding the physics of a machine. It is not aimed at professional riders, but at those who have just started to ride.
The goal of the article is not to confuse you in a huge mass of settings, but to tell a little about what can be changed and how these changes will affect the behavior of the machine.
The order of change can be very diverse, translations of books on model settings have appeared on the network, so some may throw a stone at me that, they say, I don’t know the degree of influence of each setting on the behavior of the model. I will say right away that the degree of influence of this or that change changes when the tires (off-road, road tires, micropore) and coating change. Therefore, since the article is aimed at a very wide range of models, it would be inappropriate to state the order of changes and the degree of their impact. Although, of course, I will talk about this below.
How to set up your car
First of all, you need to adhere to the following rules: make only one change per race in order to feel how the change made has affected the behavior of the car; but the most important thing is to stop at the time. You don't have to stop when you have your best lap time. The main thing is that you can confidently drive the car and cope with it in any modes. For beginners, these two things are very often not the same. Therefore, to begin with, the landmark is this - the car should allow you to easily and accurately conduct the race, and this is already 90 percent of the victory.
What to change?
Camber angle (Camber)
Camber is one of the main tuning elements. As you can see from the figure, this is the angle between the plane of rotation of the wheel and the vertical axis. For each car (suspension geometry) there is an optimal angle that gives the greatest grip. The angles are different for the front and rear suspension. The optimal camber changes as the surface changes - for asphalt one corner gives maximum grip, another for carpet, and so on. Therefore, for each coverage, this angle must be searched. Changing the angle of inclination of the wheels should be made from 0 to -3 degrees. It makes no sense anymore, tk. it is in this range that its optimal value is located.
The main idea of changing the angle of inclination is as follows:
"Larger" angle means better grip (in the case of wheels "stalling" to the center of the model, this angle is considered negative, therefore it is not entirely correct to talk about an increase in the angle, but we will consider it positive and talk about its increase)
less angle - less grip
Toe-in
Toe-in of the rear wheels increases the stability of the car on a straight line and in corners, that is, it kind of increases the grip of the rear wheels with the surface, but reduces the maximum speed. As a rule, the convergence is changed either by installing different hubs or supports of the lower arms. Basically, both have the same effect. If better understeer is required, then the toe angle should be reduced, and if, on the contrary, understeer is needed, then the angle should be increased.
Toe-in of the front wheels varies from +1 to -1 degrees (from wheel toe-out, respectively). The setting of these angles affects the moment of entry into the turn. This is the main task of convergence change. The toe angle also has a small effect on the behavior of the machine inside the bend.
larger angle - the model handles better and enters the turn faster, that is, it acquires the features of oversteer
less angle - the model acquires the features of understeer, so it enters the corner more smoothly and turns worse inside the corner

Camber angle

Negative Camber Wheel.

Camber angle is the angle between the vertical axis of the wheel and the vertical axis of the car when viewed from the front or rear of the car. If the top of the wheel is farther outward than the bottom of the wheel, this is called positive breakdown. If the bottom of the wheel is farther outward than the top of the wheel, this is called negative collapse.
The camber angle affects the handling characteristics of the car. As a general rule of thumb, increasing negative camber improves traction on that wheel when cornering (within certain limits). This is because it gives us a tire with a better cornering force distribution, a better angle to the road, increasing the contact patch and transmitting forces through the vertical plane of the tire rather than through lateral force through the tire. Another reason for using negative camber is the tendency of the rubber tire to roll against itself when cornering. If the wheel has zero camber, the inner edge of the tire's contact patch begins to lift off the ground, thus reducing the contact patch area. By using negative camber, this effect is reduced, thus maximizing the tire contact patch.
On the other hand, for the maximum amount of acceleration in the straight section, maximum grip will be obtained when the camber angle is zero and the tire tread is parallel to the road. Correct camber distribution is a major factor in the suspension design, and should include not only the idealized geometric model, but also the actual behavior of the suspension components: bending, distortion, elasticity, etc.
Most cars have some form of double-arm suspension that allows you to adjust the camber angle (as well as camber gain).

Camber Intake

Camber gain is a measure of how the camber angle changes when the suspension is compressed. This is determined by the length of the suspension arms and the angle between the upper and lower suspension arms. If the upper and lower suspension arms are parallel, camber will not change when the suspension is compressed. If the angle between the suspension arms is significant, camber will increase as the suspension is compressed.
A certain amount of camber gain is useful in keeping the tire parallel to the ground when the car rolls in a corner.
Note: the suspension arms should either be parallel or closer together on the inside (car side) than on the wheel side. Having suspension arms that are closer together on the wheel side than on the car side will cause a radical change in camber angles (the car will behave erratically).
Camber gain will determine how the roll center of the car behaves. The roll center of the car, in turn, determines how the weight transfer will occur when cornering, and this has a significant impact on handling (see below for more on this).

Caster Angle

The caster (or castor) angle is the angular deviation from the vertical axis of the suspension of a wheel in a car, measured in the longitudinal direction (the angle of the pivot axis of the wheel when viewed from the side of the car). This is the angle between the hinge line (in a car, an imaginary line that goes through the center of the upper ball joint to the center of the lower ball joint) and the vertical. The caster angle can be adjusted to optimize the handling of the car in certain driving situations.
The pivot points of the wheel are inclined so that a line drawn through them intersects the road surface slightly in front of the wheel contact point. The purpose of this is to provide some degree of self-centering of the steering - the wheel rolls behind the wheel pivot. This makes the car easier to steer and improves stability on straight sections (reducing the tendency to drift off track). Excessive caster angle will make the handling harder and less responsive, however, in off-road competition, larger caster angles are used to improve camber gain when cornering.

Toe-In and Toe-Out

Toe is the symmetrical angle each wheel makes to the longitudinal axis of the car. Toe-in is when the front of the wheels is pointing towards the centerline of the car.

Front toe angle
Basically, the increased toe (the front of the wheels are closer to each other than the rear of the wheels) provides more stability on straight sections at the cost of some slower cornering response, as well as slightly increased drag as the wheels now run slightly sideways.
Toe-in on the front wheels will result in more responsive handling and faster corner entry. However, front toe-out usually means a less stable car (more jerky).

Rear toe angle
The rear wheels of your car should always be adjusted to some degree of toe (although 0 degree toe is acceptable in some conditions). Basically, the more toe-in, the more stable the car will be. However, keep in mind that increasing the toe angle (front or rear) will reduce the speed on straight sections (especially when using stock motors).
Another related concept is that a convergence suitable for a straight section will not be suitable for a turn, as the inner wheel must go in a smaller radius than the outer wheel. To compensate for this, the steering rods are usually more or less consistent with the Ackermann steering principle, modified to fit the characteristics of a particular car.

Ackerman's angle

The Ackermann principle in steering is the geometric arrangement of the steering rods of a car designed to solve the problem of having the inner and outer wheels follow different radii when cornering.
When the car turns, it follows a path that is part of its turning circle centered somewhere along a line through the rear axle. The swiveled wheels should be tilted so that they both make an angle of 90 degrees with a line drawn from the center of the circle through the center of the wheel. Since the wheel on the outside of the bend will follow a larger radius than the wheel on the inside of the bend, it must be rotated at a different angle.
The Ackermann principle in steering will automatically compensate for this by moving the steering joints inward so that they are on a line drawn between the pivot of the wheel and the center of the rear axle. The steering joints are connected by a rigid rod, which in turn is part of the steering mechanism. This arrangement ensures that at any angle of rotation, the centers of the circles along which the wheels follow will be at the same common point.

Slip angle

The slip angle is the angle between the actual path of the wheel and the direction it is pointing. The slip angle results in a lateral force perpendicular to the direction of travel of the wheel - an angular force. This angular force increases approximately linearly for the first few degrees of the slip angle, then increases non-linearly to a maximum, after which it begins to decrease (when the wheel begins to slide).
A non-zero slip angle results from tire deformation. As the wheel rotates, the frictional force between the tire contact patch and the road causes the individual tread “elements” (infinitesimal tread sections) to remain stationary relative to the road.
This deflection of the tire results in an increase in slip angle and angular force.
Since the forces exerted on the wheels by the weight of the car are not evenly distributed, the slip angle of each wheel will be different. The relationship between slip angles will determine how the car behaves in a given corner. If the ratio of the front slip angle to the rear slip angle is greater than 1: 1, the car will understeer, and if the ratio is less than 1: 1, it will contribute to oversteer. The actual instantaneous slip angle depends on many factors, including the condition of the road surface, but the suspension of a car can be designed to provide specific dynamic characteristics.
The main means of adjusting the resulting slip angles is to change the relative roll front-to-back by adjusting the amount of front and rear lateral weight transfer. This can be achieved by changing the heights of the roll centers, or by adjusting the roll stiffness, by changing the suspension, or by adding anti-roll bars.

Weight Transfer

Weight transfer refers to the transfer of weight supported by each wheel during acceleration (longitudinal and lateral). This includes accelerating, braking, or turning. Understanding weight transfer is critical to understanding the dynamics of a car.
Weight transfer occurs as the center of gravity (CoG) shifts during the maneuvers of the car. Acceleration causes the center of mass to rotate about the geometric axis, resulting in a shift in the center of gravity (CoG). Front-to-back weight transfer is proportional to the ratio of the center of gravity height to the car's wheelbase, and lateral weight transfer (total to the front and rear) is proportional to the ratio of the center of gravity height to the car's track as well as the height of its roll center (explained below).
For example, when the car accelerates, its weight is shifted towards the rear wheels. You can observe this as the car leans back noticeably, or "crouches". Conversely, when braking, weight is transferred towards the front wheels (the nose "dives" towards the ground). Likewise, during changes in direction (lateral acceleration), weight is transferred to the outside of the corner.
Weight transfer causes a change in the available grip on all four wheels when the car brakes, accelerates, or turns. For example, since the weight is transferred to the front during braking, the front wheels do most of the braking work. This shift of "work" to one pair of wheels from the other results in a loss of total available grip.
If the lateral weight transfer reaches the wheel load at one end of the car, the inner wheel at that end will lift, causing a change in handling characteristics. If this weight transfer reaches half the car's weight, it starts to roll over. Some large trucks will roll over before sliding, and road cars usually only roll over when they leave the road.

Roll center

The roll center of a car is an imaginary point marking the center around which the car rolls (when cornering) when viewed from the front (or rear).
The position of the geometric roll center is dictated solely by the suspension geometry. The official definition of roll center is: "The point in the cross section through any pair of wheel centers at which lateral forces can be applied to the spring-loaded mass without creating suspension roll."
The roll center value can only be estimated when the car's center of mass is taken into account. If there is a difference between the positions of the center of mass and the center of roll, then a "moment shoulder" is created. When the car experiences lateral acceleration in a corner, the roll center moves up or down, and the size of the moment arm, combined with the spring rate and anti-roll bar, dictates the amount of roll in the corner.
The geometric roll center of a car can be found using the following basic geometric procedures when the car is in a static state:

Draw imaginary lines parallel to the suspension arms (red). Then draw imaginary lines between the intersection points of the red lines and the lower centers of the wheels, as shown in the picture (in green). The intersection of these green lines is the roll center.
You should note that the roll center moves when the suspension is compressed or lifted, so it is really the instant roll center. How much this center of roll moves when the suspension is compressed is determined by the length of the suspension arms and the angle between the upper and lower suspension arms (or adjustable suspension links).
When the suspension is compressed, the roll center rises higher and the moment arm (the distance between the roll center and the car's center of gravity (CoG in the illustration)) will decrease. This will mean that when the suspension is compressed (for example, when cornering), the car will have less tendency to roll (which is good if you do not want to roll over).
When using high-grip tires (foam rubber), you must set the suspension arms so that the center of roll rises significantly when the suspension is compressed. ICE road cars have very aggressive suspension arm angles to raise the roll center when cornering and prevent roll-over when using foam tires.
Using parallel, equal length suspension arms results in a fixed roll center. This means that as the car is tilted, the moment shoulder will force the car to roll more and more. As a general rule of thumb, the higher your car's center of gravity, the higher the roll center should be in order to avoid rollover.

"Bump Steer" is the tendency of the wheel to turn as it moves up the suspension travel. On most cars, the front wheels tend to toe out (the front of the wheel moves outward) when the suspension is compressed. This provides understeer when cornering (when you hit a bump while cornering, the car tends to straighten out). Excessive "bump steer" increases tire wear and makes the car jerky on uneven tracks.

"Bump Steer" and Roll Center
On a bump, both wheels lift together. When rolling, one wheel rises and the other falls. This usually produces more toe on one wheel and more toe on the other wheel, thus providing a turning effect. In a simple analysis, you can simply assume that the roll steer is similar to "bump steer", but in practice, things like the anti-roll bar have an effect that changes it.
The "bump steer" can be increased by raising the outer hinge or lowering the inner hinge. Small adjustments are usually required.

Understeer

Understeer is a condition for cornering the car in which the car's circular path has a noticeably larger diameter than the circle indicated by the direction of the wheels. This effect is the opposite of oversteer, and in simple words, understeer is a condition in which the front wheels do not follow the path the driver wants to corner, but instead follow a more straight path.
This is also often referred to as pushing or failing to turn. A car is called "jammed" because it is stable and far from drifting.
As well as oversteer, understeer has many sources such as mechanical traction, aerodynamics and suspension.
Traditionally, understeer occurs when the front wheels have insufficient traction while cornering, so the front of the car has less mechanical traction and cannot follow the trajectory in a corner.
Camber angles, ground clearance, and center of gravity are important factors that determine an understeer / oversteer condition.
It is a general rule that manufacturers deliberately tune their cars to have a little understeer. If the car has a little understeer, it is more stable (within the average driver's ability) when there are sudden changes in direction.

How to adjust your car to reduce understeer
You should start by increasing the negative camber of the front wheels (never go over -3 degrees for road cars and 5-6 degrees for off-road cars).
Another way to reduce understeer is to reduce negative rear camber (this should always be<=0 градусов).
Another way to reduce understeer is to lower the stiffness or remove the front anti-roll bar (or increase the stiffness of the rear anti-roll bar).
It is important to note that any adjustments are subject to compromise. The car has a limited amount of total grip that can be distributed between the front and rear wheels.

Oversteer

A car is oversteer when the rear wheels do not follow the front wheels but instead slide towards the outside of the bend. Oversteer can lead to skidding.
A car's tendency to oversteer is influenced by several factors such as mechanical traction, aerodynamics, suspension and driving style.
The oversteer limit occurs when the rear tires exceed their lateral grip limit during a corner before the front tires do, thus causing the rear of the car to point towards the outside of the corner. In a general sense, oversteer is a condition where the slip angle of the rear tires is greater than the slip angle of the front tires.
RWD cars are more prone to oversteer, especially when using throttle in tight corners. This is because the rear tires have to withstand lateral forces and engine thrust.
A car's tendency to oversteer usually increases when the front suspension is softened or the rear suspension is tightened (or when a rear anti-roll bar is added). Camber angles, ground clearance and tire temperature class can also be used to tune the balance of the car.
An oversteer car can also be called "free" or "unclamped".

How do you distinguish between oversteer and understeer?
When you enter a corner, oversteer is when the car turns sharper than you expect, and understeer is when the car turns less than you expect.
Oversteer or understeer is the question
As previously mentioned, any adjustments are subject to compromise. The car has limited grip that can be distributed between the front and rear wheels (this can be expanded with aerodynamics, but that's another story).
All sports cars develop a higher lateral (i.e. lateral slip) speed than the direction the wheels are pointing in. The difference between the circle the wheels roll in and the direction they point in is the slip angle. If the slip angles of the front and rear wheels are the same, the car has a neutral steering balance. If the slip angle of the front wheels is greater than the slip angle of the rear wheels, the car is said to be understeer. If the slip angle of the rear wheels is greater than the slip angle of the front wheels, the car is said to be oversteer.
Just remember that an understeer car hits the guardrail at the front, an oversteer car hits the guardrail at the rear, and a neutral car hits the guardrail at both ends at the same time.

Other important factors to consider

Any car can experience understeer or oversteer depending on road conditions, speed, available grip and driver action. The design of a car, however, tends to be at an individual "limit" condition when the car reaches and exceeds the grip limits. "Ultimate understeer" refers to a car that, by design, tends to understeer when the angular acceleration exceeds the tire grip.
The steering limit is a function of the front / rear relative roll resistance (suspension stiffness), front / rear weight distribution, and front / rear tire grip. A car with a heavy front end and low rear roll resistance (due to soft springs and / or low stiffness, or lack of rear anti-roll bars) will tend to be extremely understeer: its front tires, being heavily loaded even in a static state, will reach their grip limits earlier than the rear tires and thus develop large slip angles. Front-wheel drive cars are also prone to understeer as they usually not only have a heavy front end, but putting power to the front wheels also reduces their grip available for cornering. This often results in a "jitter" effect on the front wheels as grip changes unexpectedly due to the transfer of power from the engine to the road and control.
While understeer and oversteer can both cause a loss of control, many manufacturers design their cars for ultimate understeer on the assumption that it is easier for the average driver to control than limit oversteer. Unlike extreme oversteer, which often requires multiple steering adjustments, understeer can often be reduced by decelerating.
Understeer can occur not only during acceleration into a corner, it can also occur during hard braking. If the brake balance (braking force on the front and rear axle) is too far forward, it can cause understeer. This is caused by blocking of the front wheels and loss of effective steering. The opposite effect can also occur, if the brake balance is too far backward, the rear end of the car will skid.
Athletes, on asphalt surfaces, generally prefer neutral balance (with a slight tendency towards understeer or oversteer depending on the track and driving style), as understeer and oversteer result in a loss of speed during cornering. In rear wheel drive cars, understeer generally gives better results, as the rear wheels need some available traction to accelerate the car out of corners.

Spring rate

The spring rate is a tool for adjusting the ride height of the car and its position during suspension. Spring stiffness is a coefficient used to measure the amount of compression resistance.
Springs that are too hard or too soft will actually cause the car to have no suspension at all.
Spring rate, referred to the wheel (Wheel rate)
The spring rate, referred to the wheel, is the effective spring rate when measured at the wheel.
The stiffness of the spring, reduced to the wheel, is usually equal to or significantly less than the stiffness of the spring itself. Typically, the springs are attached to the suspension arms or other parts of the suspension pivot system. Suppose that when the wheel is offset 1 ", the spring is 0.75" biased, the lever ratio is 0.75: 1. The spring stiffness, referred to the wheel, is calculated by squaring the lever ratio (0.5625), multiplying by the spring stiffness and by the sine of the spring angle. The ratio is squared due to two effects. The ratio is applied to strength and distance traveled.

Suspension Travel

Suspension travel is the distance from the bottom of the suspension travel (when the car is on a stand and the wheels are hanging freely) to the top of the suspension travel (when the car's wheels can no longer be lifted higher). The wheel reaching the lower or upper limit can cause serious control problems. "Reaching the limit" can be caused by overshooting the travel of the suspension, chassis, or the like. or touching the road with the body or other components of the car.

Damping

Damping is the control of movement or vibration through the use of hydraulic shock absorbers. Damping controls the travel speed and suspension resistance of the car. A car without damping will oscillate up and down. With suitable damping, the car will return to normal in a minimal amount of time. Damping in modern cars can be controlled by increasing or decreasing the viscosity of the fluid (or the size of the piston bores) in the shock absorbers.

Anti-dive and Anti-squat

Anti-dive and anti-squat are expressed as a percentage and refer to the front dive when braking and the rear squat when accelerating. They can be thought of as doubles for braking and acceleration, while roll center height works in corners. The main reason for their difference is the different design goals for the front and rear suspension, while the suspension is usually symmetrical between the right and left sides of the car.
Anti-dive and anti-squat percentages are always calculated relative to the vertical plane that intersects the car's center of gravity. Let's look at anti-squat first. Determine the location of the rear instantaneous suspension center when looking at the car from the side. Draw a line from the tire contact patch through the instantaneous center, this will be the vector of the wheel's force. Now draw a vertical line through the car's center of gravity. Anti-squat is the ratio between the height of the intersection of the wheel's force vector and the height of the center of gravity, expressed as a percentage. An anti-squat value of 50% will mean that the acceleration force vector is midway between the ground and the center of gravity.

Anti-dive is the counterpart of anti-squat and works for the front suspension during braking.

Circle of forces

A circle of forces is a useful way to think about the dynamic interaction between the car tire and the road surface. In the diagram below, we are looking at the wheel from above so that the road surface lies in the x-y plane. The car to which the wheel is attached moves in the positive y direction.

In this example, the car will turn right (i.e. the positive x direction is towards the center of the turn). Note that the plane of rotation of the wheel is at an angle to the actual direction in which the wheel is moving (in the positive y direction). This angle is the slip angle.
F is limited to a dotted circle, F can be any combination of Fx (turn) and Fy (acceleration or deceleration) components that does not exceed the dotted circle. If the combination of forces Fx and Fy goes out of the circle, the tire loses grip (you slip or you are skidded).
In this example, the tire generates a force component in the x (Fx) direction that, when transmitted to the chassis of the car through the suspension system, in combination with similar forces from the rest of the wheels, will cause the car to turn to the right. The diameter of the circle of forces, and therefore the maximum horizontal force that a tire can generate, is influenced by many factors, including tire construction and condition (age and temperature range), road surface quality, and vertical wheel loading.

Critical speed

An understeer car has a concomitant mode of instability called critical speed. When approaching this speed, the control becomes more and more sensitive. At critical speed, the yaw rate becomes infinite, which means that the car continues to turn even when the wheels are straightened. Above the critical speed, a simple analysis indicates that the steering angle must be reversed (counter-steering). An understeer car is not affected by this, which is one of the reasons high-speed cars are tuned for understeer.

Finding the middle ground (or a balanced car)

A car that does not suffer from oversteer or understeer when used at its limit has neutral balance. It seems intuitive that athletes would prefer a little oversteer for turning the car around a corner, but this is not commonly used for two reasons. Early acceleration, once the car passes the corner apex, allows the car to pick up additional speed on the next straight leg. The driver who accelerates earlier or harder has a big advantage. The rear tires require some excess grip to accelerate the car in this critical cornering phase, while the front tires can devote all their grip to the corner. Therefore, the car should be tuned with a slight tendency to understeer or should be slightly "pinched". Also, an oversteer car is jerky, increasing the likelihood of losing control during prolonged competition or when reacting to an unexpected situation.
Please be aware that this is only applicable for pavement competitions. Competition on clay is a completely different story.
Some successful drivers prefer a little oversteer in their cars, preferring a quieter car that gets into corners more easily. It should be noted that the judgment about the handling balance of the car is not objective. Driving style is a major factor in the perceived balance of a car. Therefore, two drivers with identical cars often use them with different balance settings. And both can call the balance of their cars "neutral".

Model tuning is needed not only to show the fastest laps. For most people, this is absolutely unnecessary. But, even for driving around a summer cottage, it would be nice to have good and intelligible handling so that the model obeys you perfectly on the track. This article is the foundation on the path to understanding the physics of a machine. It is not aimed at professional riders, but at those who have just started to ride.

The goal of the article is not to confuse you in a huge mass of settings, but to tell a little about what can be changed and how these changes will affect the behavior of the machine.

The order of change can be very diverse, translations of books on model settings have appeared on the network, so some may throw a stone at me that, they say, I don’t know the degree of influence of each setting on the behavior of the model. I will say right away that the degree of influence of this or that change changes when the tires (off-road, road tires, micropore) and coating change. Therefore, since the article is aimed at a very wide range of models, it would be inappropriate to state the order of changes and the degree of their impact. Although, of course, I will talk about this below.

How to set up your car

First of all, you need to adhere to the following rules: make only one change per race in order to feel how the change made has affected the behavior of the car; but the most important thing is to stop at the time. You don't have to stop when you have your best lap time. The main thing is that you can confidently drive the car and cope with it in any modes. For beginners, these two things are very often not the same. Therefore, to begin with, the landmark is this - the car should allow you to easily and accurately conduct the race, and this is already 90 percent of the victory.

What to change?

Camber angle (Camber)

Camber is one of the main tuning elements. As you can see from the figure, this is the angle between the plane of rotation of the wheel and the vertical axis. For each car (suspension geometry) there is an optimal angle that gives the greatest grip. The angles are different for the front and rear suspension. The optimal camber changes as the surface changes - for asphalt one corner gives maximum grip, another for carpet, and so on. Therefore, for each coverage, this angle must be searched. Changing the angle of inclination of the wheels should be made from 0 to -3 degrees. It makes no sense anymore, tk. it is in this range that its optimal value is located.

The main idea of changing the angle of inclination is as follows:

"Larger" angle means better grip (in the case of wheels "stalling" to the center of the model, this angle is considered negative, therefore it is not entirely correct to talk about an increase in the angle, but we will consider it positive and talk about its increase)
less angle - less grip

Toe-in

Toe-in of the rear wheels increases the stability of the car on a straight line and in corners, that is, it kind of increases the grip of the rear wheels with the surface, but reduces the maximum speed. As a rule, the convergence is changed either by installing different hubs or supports of the lower arms. Basically, both have the same effect. If better understeer is required, then the toe angle should be reduced, and if, on the contrary, understeer is needed, then the angle should be increased.

Toe-in of the front wheels varies from +1 to -1 degrees (from wheel toe-out, respectively). The setting of these angles affects the moment of entry into the turn. This is the main task of convergence change. The toe angle also has a small effect on the behavior of the machine inside the bend.

larger angle - the model handles better and enters the turn faster, that is, it acquires the features of oversteer
less angle - the model acquires the features of understeer, so it enters a turn more smoothly and turns worse inside a turn

Suspension stiffness

This is the easiest way to change the steering and stability of the model, though not the most efficient. The stiffness of the spring (as, in part, and the viscosity of the oil) affects the "adhesion" of the wheels to the road. Of course, talking about changing the grip of the wheels with the road when changing the stiffness of the suspension is not correct, since it is not the grip as such that changes. But the term “adhesion change” is easier to understand. In the next article I will try to explain and prove that the grip of the wheels remains constant, but completely different things change. So, wheel grip decreases with increasing suspension stiffness and oil viscosity, but you cannot increase the stiffness excessively, otherwise the car will become nervous due to the constant separation of the wheels from the road. Installing soft springs and oil increases traction. Again, don't run to the store looking for the softest springs and oil. Excessive traction causes the car to slow down too much when cornering. As the racers say, she starts to "get stuck" in the corner. This is a very bad effect, as it is not always easy to feel it, the car can have excellent balance and good handling, and the lap times deteriorate dramatically. Therefore, for each coverage, you will have to find a balance between the two extremes. As for the oil, on hummock trails (especially on winter trails built on a plank floor) it is necessary to fill up with very soft 20 - 30WT oil. Otherwise, the wheels will start to lift off the road and the traction will decrease. On flat trails with good grip, 40-50WT is fine.

When adjusting the suspension stiffness, the rule is as follows:

the stiffer the front suspension, the worse the car turns, it becomes more resistant to rear axle drift.
the softer the rear suspension, the less the model turns, but becomes less prone to rear axle drift.
the softer the front suspension, the more pronounced oversteer, and the higher the tendency to drift of the rear axle
the stiffer the rear suspension, the more the handling becomes oversteer.

The angle of inclination of the shock absorbers

The angle of inclination of the shock absorbers, in fact, affects the stiffness of the suspension. The closer to the wheel the lower mount of the shock absorber (we move it to hole 4), the higher the stiffness of the suspension and, accordingly, the worse the adhesion of the wheels to the road. Moreover, if the upper mount is also moved closer to the wheel (hole 1), the suspension becomes even more rigid. If you move the attachment point to hole 6, the suspension becomes softer, as in the case of moving the upper attachment point into hole 3. The effect of changing the position of the shock absorber attachment points is the same as changing the stiffness of the springs.

Kingpin tilt angle

The tilt angle of the king pin is the angle of inclination of the axis of rotation (1) of the steering knuckle relative to the vertical axis. The people call the pivot a pivot (or hub) in which the steering knuckle is installed.

The main influence of the angle of inclination of the king pin is at the moment of entry into the turn, in addition, it contributes to the change in controllability within the turn. As a rule, the angle of inclination of the king pin is changed either by moving the upper link along the longitudinal axis of the chassis, or by replacing the king pin itself. An increase in the angle of inclination of the king pin improves the entrance to the turn - the car enters it more sharply, but there is a tendency to skid the rear axle. Some people believe that at a large angle of inclination of the kingpin, the exit from the turn with an open throttle worsens - the model floats out of the turn. But from my experience in model management and engineering experience, I can say with confidence that it does not affect the exit from the turn. Decreasing the tilt angle worsens corner entry - the model becomes less sharp, but easier to control - the car becomes more stable.

The angle of inclination of the swing axis of the lower arm

It's good that some of the engineers thought of changing such things. After all, the angle of inclination of the levers (front and rear) affects only the individual phases of the passage of the turn - separately for the entrance to the turn and separately for the exit.

The exit from the turn (on gas) is influenced by the angle of inclination of the rear levers. With an increase in the angle, the grip of the wheels with the road "deteriorates", while at an open throttle and with the wheels turned, the car tends to go to the inner radius. That is, the tendency to skid of the rear axle increases when the throttle is open (in principle, with poor adhesion of the wheels to the road, the model can even turn around). With a decrease in the angle of inclination, the grip during acceleration improves, so it becomes easier to accelerate, but there is no effect when the model tends to go to a smaller radius on gas, the latter, with skillful handling, helps to quickly go through corners and get out of them.

The tilt angle of the front levers affects corner entry when throttle is released. As the lean angle increases, the model enters the corner more smoothly and acquires understeer features at the entrance. As the angle decreases, the effect is correspondingly opposite.

Lateral Roll Center Position

center of mass of the machine
upper arm
lower arm
roll center
chassis
wheel

The roll center position changes the grip of the wheels when cornering. The roll center is the point about which the chassis rotates due to inertial forces. The higher the center of roll is (the closer it is to the center of mass), the less roll and more traction. That is:

Raising the center of roll at the rear will impair steering but increase stability.
Lowering the roll center improves steering but reduces stability.
Increasing the center of roll at the front improves steering, but reduces stability.
Lowering the center of roll at the front will impair steering and increase stability.

Finding the center of the roll is very simple: mentally extend the upper and lower levers and determine the point of intersection of the imaginary lines. From this point we draw a straight line to the center of the contact patch of the wheel with the road. The intersection of this line and the center of the chassis is the roll center.

If the attachment point of the upper arm to the chassis (5) is lowered down, the center of roll will rise. If you raise the attachment point of the upper arm to the hub, the roll center will also rise.

Clearance

Ground clearance, or ground clearance, affects three things - roll-over stability, traction, and handling.

With the first point, everything is simple, the higher the clearance, the higher the tendency of the model to overturn (the position of the center of gravity increases).

In the second case, the increase in ground clearance increases the roll in the corner, which in turn worsens the traction of the wheels.

With the difference in ground clearance in front and behind, the following thing is obtained. If the front clearance is lower than the rear, then the roll in front will be less, and, accordingly, the grip of the front wheels with the road is better - the car will become oversteer. If the rear clearance is lower than the front, then the model will acquire understeer.

Here's a quick summary of what can be changed and how it will affect the behavior of the model. To begin with, these settings are enough to learn how to drive well without making mistakes on the track.

Sequence of changes

The sequence can be varied. Many top riders change only what will eliminate the imperfections in the car's behavior on a given track. They always know what exactly they need to change. Therefore, we must strive to clearly understand how the car behaves in corners, and what in the behavior does not suit you specifically.

As a rule, the factory settings are included with the machine. Testers who select these settings try to make them universal for all tracks as much as possible so that inexperienced modelers do not climb into the jungle.

Before starting training, you need to check the following points:

set clearance
install the same springs and fill in the same oil.

Then you can start setting up the model.

You can start tweaking the model small. For example, from the angles of inclination of the wheels. Moreover, it is best to make a very big difference - 1.5 ... 2 degrees.

If there are small flaws in the behavior of the car, then they can be eliminated by limiting the corners (remember, you should easily cope with the car, that is, there should be a little understeer). If the disadvantages are significant (the model unfolds), then the next stage is to change the angle of inclination of the king pin and the positions of the roll centers. As a rule, this is enough to achieve an acceptable picture of the car's handling, and the nuances are introduced by the rest of the settings.

See you on the track!

On the eve of important competitions, before the end of the assembly of a KIT set of a car, after accidents, at the time of buying a car with a partial assembly and in a number of other predictable or spontaneous cases, there may be an urgent need to buy a remote control for a radio-controlled typewriter. How not to miss a choice, and what features should you pay special attention to? This is what we will tell you about below!

Varieties of remote controls

The control equipment consists of a transmitter, with the help of which the modeler sends control commands and a receiver installed on the car, which catches the signal, decodes it and transmits it for further execution by executive devices: servos, regulators. This is how the car drives, turns, stops, as soon as you press the corresponding button or perform the necessary combination of actions on the remote control.

Car modelers mainly use pistol-style transmitters where the remote control is held in the hand like a pistol. The throttle trigger is located under the index finger. When you press back (towards yourself), the car goes, if you press in front, it brakes and stops. If no force is applied, the trigger will return to the neutral (middle) position. There is a small wheel on the side of the remote control - this is not a decorative element, but the most important control tool! With its help, all turns are performed. Clockwise rotation of the wheel turns the wheels to the right, counter-clockwise directs the model to the left.

There are also joystick transmitters. They are held with two hands, and are controlled by the right and left sticks. But this type of equipment is rare for high-quality cars. They can be found on most aerial vehicles, and in rare cases - on toy radio-controlled cars.

Therefore, with one important point, how to choose a remote control for a radio-controlled car, we have already figured out - we need a pistol-type remote control. Move on.

What characteristics should you pay attention to when choosing

Despite the fact that in any model store you can choose both simple, budget equipment, and very multifunctional, expensive, professional, general parameters that you should pay attention to will be:

Frequency
Hardware channels
Range of action

Communication between the remote control for a radio-controlled car and the receiver is provided using radio waves, and the main indicator in this case is the carrier frequency. Recently, modelers are actively switching to 2.4 GHz transmitters, as it is practically immune to interference. This allows you to collect a large number of radio-controlled cars in one place and start them simultaneously, while equipment with a frequency of 27 MHz or 40 MHz reacts negatively to the presence of foreign devices. Radio signals can overlap and interrupt each other, due to which control over the model is lost.

If you decide to buy a remote control for a radio-controlled car, you will probably pay attention to the indication in the description of the number of channels (2-channel, 3CH, etc.) We are talking about control channels, each of which is responsible for one of the model's actions. As a rule, for the car to drive, two channels are sufficient - engine operation (gas / brake) and direction of travel (turns). You can find simple toy cars in which the third channel is responsible for remote switching on of headlights.

In sophisticated professional models, a third channel for controlling the mixture formation in the internal combustion engine or for locking the differential.

This question is interesting to many beginners. Sufficient range so that you can feel comfortable in a spacious hall or on rough terrain - 100-150 meters, then the machine is lost from sight. The power of modern transmitters is enough to transmit commands over a distance of 200-300 meters.

An example of a high-quality, budgetary remote control for a radio-controlled car is. This is a 3-channel system operating in the 2.4GHz band. The third channel gives more opportunities for the modeler's creativity and expands the functionality of the car, for example, it allows you to control headlights or turn signals. In the transmitter's memory, you can program and save settings for 10 different car models!

Radio control revolutionaries - the best remotes for your car

The use of telemetry systems has become a real revolution in the world of radio-controlled cars! The modeler no longer needs to guess what speed the model develops, what voltage the on-board battery has, how much fuel is left in the tank, to what temperature the engine has warmed up, how many revolutions it makes, etc. The main difference from conventional equipment is that the signal is transmitted in two directions: from the pilot to the model and from the telemetry sensors to the console.

Miniature sensors allow you to monitor the condition of your car in real time. The required data can be displayed on the remote control display or on the PC monitor. Agree, it is very convenient to always be aware of the "internal" state of the car. Such a system is easy to integrate and easy to configure.

An example of an "advanced" type of remote control -. The device works on the "DSM2" technology, which provides the most accurate and fast response. Other distinctive features include a large screen, which graphically displays data about the settings and the state of the model. Spektrum DX3R is considered the fastest of its kind and is guaranteed to lead you to victory!

In the Planeta Hobby online store, you can easily select equipment for controlling models, you can buy a remote control for a radio-controlled car and other necessary electronics :, etc. Make your choice right! If you cannot decide on your own, please contact us, we will be happy to help!