Home Quadcopter Diy RC Car Speed Calculator: 3 Straightforward Calculation Methods

RC Car Speed Calculator: 3 Straightforward Calculation Methods

Remote control (RC) cars are a popular source of entertainment and competition, with many enthusiasts seeking to maximize their vehicle’s top speed. Calculating the maximum speed of an RC car is not overly complex but requires some basic information and simple mathematical calculations. This article will introduce 3 straightforward calculation methods to help you better understand and master your RC car’s performance.

I. What information is needed to calculate RC car speed?

Before diving into calculating your RC car’s top speed, you’ll need to gather the following information:

Motor RPM (Revolutions Per Minute): This is the number of revolutions the motor makes in one minute. You can find this information in the motor’s specifications or the manufacturer’s website when purchasing an RC car. It is usually available in the motor’s spec sheet or on the manufacturer’s website. Maybe you know the KV value, how to convert brushless motor kv to rpm? Click to know: KV To RPM Calculator

Spur Gear Size (T): Refers to the number of teeth on the spur gear, which is connected to the motor shaft.

Pinion Gear Size (T): Refers to the number of teeth on the pinion gear, which is connected to the wheel axle. This information can typically be found in the RC car’s user manual, or if you purchased a vehicle kit, it will be listed in the parts inventory.

Internal Gear Ratio of the transmission: This is the ratio of the internal gears in the transmission, which affects the vehicle’s overall gear ratio. You can find detailed information about the vehicle’s transmission system in the user manual or on the manufacturer’s website.

Wheel Diameter (inches): This is the diameter of the wheels, used to calculate the distance the vehicle travels in one wheel revolution, i.e., the wheel’s circumference. Measuring the wheel diameter is a straightforward and direct method. You can use a tape measure or a measuring instrument to measure the wheel’s diameter.

Having this information will enable you to determine your RC car’s top speed using different calculation methods. Let’s explore each of these methods in detail.

II. RC Car Speed Calculator Way 1: Theoretical Calculation

This method involves using basic mathematical formulas to estimate the RC car’s top speed. It assumes no external factors like air resistance, friction, or gravity, making it a theoretical calculation.

The formula used for the calculation is as follows:

RC Car Top Speed = Motor RPM / (Spur Gear Size (T)/ Pinion Gear Size (T) × Internal Gear Ratio of the transmission) × Wheel Circumference × 60 minutes × 1.578 / 100000

Please note that 1.578/100000 is used to convert inches to feet. Although some factors are ignored in the calculation, this method still provides a good estimation of the vehicle’s theoretical speed.

Example:

Let’s assume you have an RC car with

a motor RPM of 25,000,

a spur Gear Size (T) of 20,

a pinion Gear Size (T) of 80,

an internal Gear Ratio of 2.0,

a wheel diameter of 4 inches.

RC Car Top Speed = 25,000 / (80 / 20 × 2.0）× (4 × 3.14159) × 60 × 1.578 / 100000 = (25,000 / 8) ×12.566 × 60 × 0.00001578 = 37.18 miles per hour

III. RC Car Speed Calculator Way 2: Purchase Speed Testing Meter

For those who don’t want to perform complex calculations, you can consider purchasing speed testing equipment such as the SkyRC GPS Speed Meter. These devices are available from reputable brands like SkyRC and can be purchased from RC car retailers, online stores, or the manufacturer’s official website.

By using speed testing equipment like the SkyRC GPS Speed Meter, you can accurately measure your RC car’s speed and altitude, providing real-time data to conveniently assess your vehicle’s performance. The SkyRC GPS Speed Meter comes with a compact GPS module and a concealed antenna design, weighing only 41 grams. Its highly sensitive GPS receiver chip allows for rapid positioning and allows the controller to record real-time speed and altitude. You can view speed, altitude, total mileage/kilometers, longitude, and latitude information at any time, enabling you to fine-tune your RC car for optimal performance.

IV. RC Car Speed Calculator Way 3: Video Speed Measurement with a Digital Camera

This is another simple and rough method where you can use a digital camera and some basic measurements to calculate your RC car’s speed. You need to mark two lines on a flat surface and ensure they are a certain distance apart. By recording a video of your car traveling between the two lines at its highest speed and using timing tools, you can measure the time taken and calculate the vehicle’s speed.

By analyzing the video frame by frame, you can determine the time taken from one point to another and, consequently, calculate the speed. While this method may not be as precise as professional equipment, it is a simple and viable option for most hobbyists.

Example:

On a flat surface, draw two lines 50 feet apart, leaving enough space on either side for the RC car to brake. Then, using a digital camera, record a video of the RC car traveling between these lines at its highest speed. By analyzing the video frame by frame, you determine that the car takes 2.5 seconds to travel from one line to the other.

RC Car Speed = 50 feet / 2.5 seconds × 0.68 = 13.6 miles per hour

V. RC Car Speed Calculator Way 4: Manual Speed Measurement

This method requires no special equipment, only some simple measurements and a stopwatch. You need to draw two lines 100 feet apart on a flat surface and ensure there is enough space on both sides for the RC car to brake and reach its top speed. Then, have your RC car travel between the two lines, and record the time it takes using a stopwatch.

By conducting multiple measurements and taking an average, you can calculate the time the vehicle takes to cover the 100 feet distance. Then, with a simple mathematical calculation, divide 100 by the average time and multiply by 0.68 to obtain the vehicle’s speed in miles per hour.

Manual speed measurement is a simple and straightforward method that requires no special equipment, only basic measuring tools and a timer. Let’s demonstrate how to manually measure an RC car’s top speed with a practical example.

Example:

Assume you have a 1/10 scale electric RC car, and you want to measure its top speed. First, find a flat, obstacle-free straight track or open area. Then, follow these steps to manually measure the speed:

Step 1: Preparation Before selecting the test location, ensure that there is no wind or other interfering factors and that the area is safe, with no people or other vehicles present.

Step 2: Mark Starting and Finishing Points Use ropes or other markers to indicate the starting and finishing points on the ground. Set the distance between the two markers at 100 feet for a more accurate measurement.

Step 3: Warm-Up Before beginning the test, give your RC car a brief warm-up time to ensure it is in optimal condition.

Step 4: Test Have the RC car start from the starting point, accelerate to its top speed, and maintain that speed until it reaches the finishing point. At the same time, use a timer to record the time it takes for the car to travel from the starting point to the finishing point.

Step 5: Multiple Tests Conduct multiple tests and record the time for each one. This helps reduce measurement errors and provides a more accurate result.

Step 6: Calculate Speed Use the following formula to calculate the RC car’s top speed: Speed (miles per hour) = 100 (feet) / Average Time (seconds) × 0.68

For example,

After conducting 5 tests, you get the following test times: 1.6 seconds, 1.7 seconds, 1.8 seconds, 1.7 seconds, and 1.9 seconds.

Average Time = (1.6 + 1.7 + 1.8 + 1.7 + 1.9) / 5 = 1.74 seconds

Speed = 100 (feet) / 1.74 (seconds) × 0.68 ≈ 39.08 miles per hour

Through manual speed measurement, you have successfully calculated your RC car’s top speed, which is approximately 39.08 miles per hour.

VI. Common Transmission Ratios for RC Cars:

Extreme High-speed tracks: 4.5:1 – 5.0:1
Fast High-speed tracks: 4.0:1 – 4.5:1
Moderate High-speed tracks: 3.5:1 – 4.0:1
All-purpose tracks: 3.0:1 – 3.5:1
Moderate Low-speed tracks: 2.0:1 – 2.5:1
Slow Low-speed tracks: 1.5:1 – 2.0:1
Extreme Low-speed tracks: 1.0:1 – 1.5:1

The transmission ratio plays a crucial role in determining the balance between acceleration and top speed of an RC car. Different tracks and driving styles require different transmission ratios to optimize performance. For high-speed tracks, a higher transmission ratio will provide more top speed at the cost of slower acceleration, while for low-speed tracks, a lower transmission ratio will improve acceleration at the expense of top speed. As with tire sizes and gear ratios, selecting the appropriate transmission ratio can greatly enhance your RC car’s overall performance on the specific track you’re racing on.

VII. Common Internal Gear Ratios for RC Cars:

Among RC car enthusiasts, there are some common internal gear ratios that influence the vehicle’s acceleration performance and top speed.

Some common internal gear ratios include:

2.0:1

2.5:1

3.0:1

3.5:1

4.0:1

These ratios cater to different tracks and driving styles. Lower gear ratios can provide higher acceleration performance, while higher gear ratios offer higher top speeds. Selecting the appropriate internal gear ratio is crucial for optimizing your RC car’s performance.

VIII. Common Wheel Diameters for RC Cars:

On the market, there are various RC car wheel sizes to choose from. Some common wheel diameter sizes are as follows:

2 inches

2.2 inches

2.4 inches

2.8 inches

3.0 inches

The wheel diameter directly impacts ground clearance and performance when traversing different terrains. Larger diameter wheels are typically suitable for off-road and uneven terrain, while smaller diameter wheels are more suitable for flat and high-speed tracks. Choosing the wheel diameter that suits your vehicle and driving needs will help you achieve better handling and driving experience.

IX. Popular Tire Sizes:

JConcepts Goose Bumps: 108 mm

Sweep Racing Terrain Crusher: 116 mm

Aka Racing Enduro: 105 mm

Team Losi Racing (TLR) Eclipse: 98 mm

Schumacher Mini Dart: 86 mm

DuraTrax Posse: 102 mm

Traxxas Anaconda: 88 mm

HPI Racing V-Groove: 92 mm

Team Associated Double Dee’s: 100 mm

These tire sizes cater to different RC car models and track conditions, offering various performance characteristics such as traction, grip, and durability. Depending on your driving preferences and the type of surface you’ll be racing on, choosing the right tire size is essential for optimizing your RC car’s performance.

Conclusion:

Regardless of the method you choose to calculate your RC car’s top speed, these simple calculations will provide you with a better understanding of your vehicle’s performance. From theoretical calculations to practical measurements, each method has its advantages and appropriate applications. By mastering these calculation methods, you can fine-tune and optimize your RC car to reach its peak performance, offering more excitement and challenges. Enjoy the passion of RC car driving!

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