High Speed RC Jet Car Is A Harsh Teacher

August 28, 2022 by Danie Conradie 8 Comments

Making machines go fast has always been a seemingly unavoidable impulse for humans. With the advent of radio control, it’s possible to get a taste of the rush without putting your life and too much money on the line. In the spirit of speed, [James Whomsley] strapped a jet turbine engine to an RC car, and learned some hard lessons along the way.

The car started as a four-wheel drive electric race car, but [James] removed most of the drive train components and mounted the jet turbine engine on a pair of 3D printed struts. Originally intended for large-scale RC planes, the little jet engine produces about 120 N of thrust. To allow the car to stop, [James] kept the drive shafts and connected them to a centrally mounted disk brake unit.

For the first high-speed test runs, James added a vacuum-formed shell and a pair of large vertical stabilizers for high-speed stability. On the 3rd test run at a local racetrack, the car got up to 190 km/h (118 MPH) before it veered off the track and crashed. Fortunately, the chassis and engine only sustained minor damage and were easy to repair.

James rebuilt the car with a lower engine to reduce the center of gravity and added an electronic gyro in an attempt to stabilize the car at high speed. Time ran out, and he wasn’t able to test the car before taking it to a high-speed RC event held on a runway. This led to another crash when the car again veered off the track after badly oscillating. After checking the onboard footage, [James] discovered the receiver had experienced a loss of signal, and an incorrect fail-safe setting made the engine go full throttle. After more tests, James also found that excessive play in the steering mechanism had caused the gyro to induce oscillations.

Although this car failed in the end, [James] intends to take the lessons learned into a new high-speed car build. [rctestflight] also did some testing with an EDF-powered RC car recently, and used a drone flight controller for high speed stability. This is not [James]’ first foray into speed machines, having previously experimented with a rocket plane.

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Electric Land Speed Racing Can Be Lightning Fast

July 8, 2021 by Lewin Day 4 Comments

Land speed racing is a pursuit of ultimate speed above all else. Most cars typically run on huge, flat salt pans, and racers run flat out for miles in a straight line, attempting to push their machines to the limit. Like most motorsports, the history of land speed racing has traditionally been centred around internal combustion, but electric racers have long been out there chasing land speed records as well.

The Need For Speed

At the most famous land speed trials, such as Bonneville’s Speed Week, speed runs take place over miles and miles of open salt, with timing traps along the way to determine competitor’s speeds. These tracks are long enough that acceleration is of little concern, which is of great benefit to electric runners. Additionally, only one or two runs is required to set a record. This means that heavy batteries aren’t always needed, as the distance a competitor must travel is short, and even if the batteries are heavy, it doesn’t excessively affect top speed.

With an eye to that, land speed competitors in electric classes are typically classified into weight classes. This is due to the fact that bigger, heavier battery packs can deliver more current, and thus potentially have a performance advantage over lighter vehicles. Thus, typical classes run by most salt flats competitions involve the E1 class, which allows for vehicles under 1100 lbs, the E2 class, for vehicles up to 2200 lbs, and the E3 class, which is for anything 2200 lbs and above. The FIA also publish their own set of classes, again separated by weight, though to a much more granular degree.

Procedures for setting records vary depending on the venue and the record in question. Local records at salt venues like El Mirage can typically be broken with a single run faster than the standing record, while Bonneville Speed Week competitors must set a higher average speed across two runs on two consecutive days. FIA records differ again, and are perhaps the most stringent, requiring competitors to set a faster average across two runs in opposite directions, set within an hour of each other, to attempt to minimise the effect of wind on the result. Things can sometimes get confusing, as many FIA records, for example, are set at the Bonneville salt flats, but not actually in Speed Week competition or by Speed Week rules. Continue reading “Electric Land Speed Racing Can Be Lightning Fast” →

How To Get Into Cars: Land Speed Racing

June 17, 2021 by Lewin Day 12 Comments

Land speed racing is one of the oldest forms of motorsport, and quite literally consists of going very, very fast in (ideally) a straight line. The higher the speed your car can attain, the better! It’s about the pure pursuit of top speed above all else, and building a car to compete is a calling for a dedicated few. If you’d like to join them, here’s how to go about it.

Faster, Faster, Faster!

A great example of the “36HP” Volkswagen class, which challenges competitors to set land speed records using only classic VW engines, with categories for various levels of modification. Note the aero wheels and raked stance. Credit: Utah Salt Flats Racing Association

While taking the outright land speed record typically requires a jet-engined sled of singular design, there is plenty of land speed competition to be had in various classes for competitors fielding their own entries. There are vintage classes for older technology engines, still popular from the dawn of hotrodding, like Ford Flathead V8s and other contemporary motors. There are also classes split by engine displacement, number of cylinders, aerodynamic modifications, or the type of fuel used.

Racers often pick a record or set of records they wish to beat – for example, wanting to set the the fastest speed for a gasoline-powered, naturally-aspirated four cylinder – and build their car to that end. Alternatively, a racer might build a car with a large V8 engine, for example, to compete in one class, and then disable several cylinders on a later run to try and snatch records in lower classes as well. Continue reading “How To Get Into Cars: Land Speed Racing” →