Efficient engine equals race wins

One of the sweeping changes in the Red Bull Air Race rules in 2014 was standardization of the raceplane engines, making for a more level playing field. Ever since, the teams have all been trying to get more – hopefully much more – out of that race-tuned Lycoming power plant than their opponents. And that means being efficient.

The six-cylinder Lycoming engine has a solid history in the world of competition aerobatics. However, the version used in the raceplanes has been customized to the exact specifications of the Red Bull Air Race, with every one built in Lycoming’s Advanced Technology Center.

Keeping cool

To be as powerful as possible, a raceplane engine needs cool, dense air running through it. That is the job of the inlets on the front of the engine cowling – what appear like “holes” near the nose of the plane that together with the propeller often resemble a “face.” If you look closely, you will notice that the faces of the 14 raceplanes are each a bit different, and that is because every team technician has his own thoughts on the best way to cool the engine.

The technicians in the Red Bull Air Race know that the air inlets of their raceplane can create the difference between winning and losing. The engine not only needs plenty of cool air to be sucked in, but to get hot air out quickly as well. Optimizing the airflow over the cylinders and the oil cooler is a difficult challenge in every track and climate – but with possible temperatures of 25°C or more in Abu Dhabi, keeping the engine’s temperature cool will be absolutely essential for a competitive time.

Think about exercising. If you run in high temperatures and at low air density (the “thin” air of high altitude), you will find it difficult to breathe and to perform at your best. A clear, cool day close to sea level is what you need for easy breathing and good running. A highly tuned race engine works the same way, but the “breathing” has to be a compromise: Make the inlets too small, and the engine will get hot and lose power. Make them too large, and they will create too much drag, slowing the raceplane down.

Figuring out the best cooling refinements for the raceplane is a unique challenge for the technicians, because the type of flying in the Red Bull Air Race can not be compared to anything else.

It’s in the mix

Even though the pilots can not control the temperature at the race locations, there is something they can do to ensure that they are running their engine at its optimum – they must get the fuel mixture correct. To run at peak performance and for perfect, efficient combustion to occur, the engine needs the ratio of air to fuel to be 14.7 parts air to one part fuel. The pilots have a manual control that adjusts the fuel mixture, but it is a delicate balancing act.

If there is too much fuel in the mixture, it will be too “rich,” and some will be left in the combustion chamber, meaning the engine will lose power. On the other hand, if there is too little fuel in the mixture, it will run “lean”, again losing power. For the teams to make sure they are getting the correct mixture into their engines, some have added a device called a lambda sensor.

Red Bull Air Race Technical Director Jim “Jimbo” Reed explains: “The sensor measures the CO2 [carbon dioxide], similar to a sensor in a car. There is a display in the cockpit that reads the stoichiometric number, which measures particle density. If you have more fuel per air, then it reads a lower number because there is not as much carbon produced. As you start to get to the correct mixture, a certain number pops up that tells you you’re doing the right thing.”

The lambda sensor, which is placed in the exhaust to collect the readings, works in all conditions, no matter the altitude or temperature. “The conditions don’t make a difference to the 14-to-one ratio, so you want the same readout – but if you’re at a higher altitude, you’ll be taking in less air, so you need less fuel to keep the same ratio,” continues Reed.

The Technical Director goes on to emphasize that getting the mixture right can make a huge difference in the racetrack. “The mixture ratio is linear to the horsepower produced, so if you can keep the engine cool enough and can maintain the mixture correctly, you’ll get maximum power,” he says. “This is essential to a fast race, because from full-rich to full-lean in the engine you can have a difference in horsepower of eight percent!”

See which team can run their engine efficiently enough to take the early season lead: Tickets for the Red Bull Air Race season opener in Abu Dhabi on 2-3 February are on sale now. For all the latest news and information, visit www.redbullairrace.com.

Red Bull Air Race 2018 Calendar
2-3 February: Abu Dhabi, UAE
21-22 April: Cannes, France
26-27 May: Europe, location TBA
23-24 June: Budapest, Hungary
4-5 August: Asia, location TBA
25-26 August: Kazan, Russia
6-7 October: Indianapolis, USA
November: Asia, location TBA

About Red Bull Air Race
Created in 2003, the Red Bull Air Race World Championship has held more than 80 races around the globe. The Red Bull Air Race World Championship features the world’s best race pilots in a pure motorsport competition that combines speed, precision and skill. Using the fastest, most agile, lightweight racing planes, pilots hit speeds of 370kmh while enduring forces of up to 10G as they navigate a low-level slalom track marked by 25-meter-high, air-filled pylons. In 2014, the Challenger Cup was conceived to help the next generation of pilots develop the skills needed for potential advancement to the Master Class that vies for the World Championship.