The following interview was conducted with Mark Taylor of FTR Moto2 early in 2011. MotoMatters.com visited FTR's factory in Buckingham last year and spoke to Taylor about the development of the British Moto2 chassis builder's radically revised fairing, and the role of computational fluid dynamics in designing and verifying the aero packages of racing motorcycles. Taylor and FTR graciously discussed their work in some depth, and offered us a glimpse into exactly what goes into designing a racing motorcycle.
When the 2011 FTR Moto2 machine made its debut at the Valencia Moto2 tests at the start of last year, the one thing that caught the eye was the seemingly huge circular air intake on the front of the bike. The large hole, quickly dubbed "the gaping maw", was a radical departure from the current paddock fashion of letterbox-style air intakes, with long, thin, and often nipped in the middle the shape gracing most racing motorcycles at present.
So why did FTR decide to buck the trend and go with the great big hole on the front of the fairing? We spoke to FTR's engineering guru Mark Taylor at the Moto2 chassis manufacturer's Buckinghamshire base and put exactly that question to him.
The change, Taylor explained, came out of computer modeling work that FTR had undertaken over the winter. Some Computational Fluid Dynamics, or CFD, modeling had been done on the 2010 bodywork to identify the strengths and weaknesses of the fairing. The CFD models had highlighted a number of areas for improvement, both internally and externally on the bike.
The circular air inlet was part of a push to raise airbox air pressure, Taylor said, airbox pressure being a key ingredient of engine performance at high revs. The higher the airbox pressure, the more air there is going into the cylinders, and the more oxygen there is to mix with fuel. CFD modeling had shown that on the old design - a thin, letterbox shape pinched in the middle - the route that incoming air took on its way into the airbox meant there were a number of places where eddies and turbulence caused pressure to drop, reducing the effective charge into the airbox and meaning filling was less than optimum.
The circular inlet killed two birds with one stone. By virtue of both its shape and its location, the round hole took more incoming air straight into the airbox, making use of the point of maximum air pressure on the nose of the fairing. "This point here, right on the nose, is a big dollop of drag," Taylor said, indicating a large red button of high pressure on the nose of the 2010 fairing in a CFD diagram. "You've got this great big knob of drag, straight on the bib of the nose." By putting the circular air intake right behind that point, FTR was able to turn that pressure point to its advantage.
The higher location of the intake - or rather of its center - added a secondary benefit as well. On the old design, the air was led up and then along the steering stem, before being forced into the airbox proper. The new circular inlet meant that the air passage into the airbox no longer had to be moved up, but could be channeled more or less directly into the top of the airbox.
"You can see here that the section behind the inlet is creating a bit of a problem," Taylor explains, pointing to a region of low pressure in the inlet path of the 2010 design, "as the air is coming in, it's slowing the air, it's creating turbulence behind it." The old inlet had another problem too: "The other thing is you're taking the air up, and then asking it to come down."
The circular shape itself was also an advantage, Taylor said. "The other problem with [a narrow, letterbox intake like on the 2010 FTR] is that you've got a boundary layer of air, say about 5 millimeters around the entry." The boundary layer is the region of air directly next to the surface of the air intake, which is slowed by the surface, creating drag. "So the real intake area is actually much smaller. With a thin, narrow intake, the area occupied by the boundary layer is very large in proportion to the actual intake area." As a circle has the smallest circumference - and therefore the smallest boundary area - a circular intake gives the largest area of intake with the smallest losses to drag in the boundary layer.
The 2010 FTR Moto2 bike, ridden by Jason DiSalvo at Indianapolis, with the thin intake
A year later: the 2011 FTR Moto2 bike with the large, circular intake, ridden by Tito Rabat at Indianapolis
That physical aspect was what made the intake look so strange. Used to smaller, thinner, more rectangular intakes, suddenly seeing a gaping circle came as something of a shock to most racing fans. But the look of the intake was deceptive, Taylor said, sketching the original intake shape on a notepad to illustrate his point. He then illustrated the idea behind the circular intake with simple action, miming taking hold of the top part of the thin letterbox shape, and pulling it upwards, as if pulling apart the two long edges, restoring a circle which had been squashed. "The new, round intake looks very big doesn't it?" Taylor said, an impish grin on his face, "but actually, if you flatten it out, it's about the same size as the old "letterbox" style intake. People always say it looks massive, but actually, it's not that much bigger."
The circular intake does not remove the drag created by the forward point of the fairing, the point at which the fairing pushes through the air, Taylor clarified, but it did allow FTR to make the best use of both the air pressure on the fairing and the layout of the steering head. "You're always going to encounter a dollop of drag on the nose," Taylor said, "but by using the circular air intake, the bottom point of the intake is in exactly the same place and we've brought the intake up and created a smooth path into the airbox. We've lost the turbulence and pressure drop caused by asking the air to change direction." The FTR engineering mastermind dismissed arguments that excess air spilling over from airbox would cause more turbulence around the air intake, and spread out over the fairing causing more drag. "There is this argument that the air can go in and then bounce straight back out again," Taylor explained, "but a lot of that is handled by what we've done further down the intake, by tapering and angling it."
Results from CFD modeling were more than promising, showing a theoretical 21% increase in airbox pressure and a 1% decrease in drag. In practice, the gains were lower, but impressive nonetheless. When the Moto2 teams running the FTR chassis received their 2011 machines at the Valencia tests back in February, the data showed that airbox pressure was up by 10% over the 2010 model, and well above the numbers reported by the teams running the Suter package. More importantly, airbox pressure stayed stable even at high revs, not dropping off as the engine tries to suck as much air as possible out of the airbox.
The gains can even be felt by the rider. Speaking after the Qatar Moto2 round, Avintia-STX rider Kenny Noyes - contesting the 2011 Moto2 championship on a Fogi Racing FTR - said he really noticed it down Qatar's long front straight. "I could just pass the other guys on the gas," Noyes said, "I didn't really have to try to slipstream them much."
Those results - both in terms of data and rider feedback - have been crucial to FTR, not just as validation of the work they have done, but also as a tool to persuade the teams that the intake shape was a step in the right direction. The conservatism of the racing teams has been the biggest surprise to FTR, Taylor said, and persuading them that certain engineering directions were the right thing has proven almost impossible sometimes.
Most of the Moto2 teams came out of the 250cc class, and were used to having Aprilia tell them exactly what would work and what wouldn't, and what they could change and what they couldn't That left the teams afraid to experiment and step outside of the boundaries of the familiar. Taylor sums the situation up pithily: "The big problem with the racing teams is they're so blinkered. If it wasn't done on a Matchless in 1966, then it's probably a stupid idea and there's no point bothering."
Being able to point to the data has allowed FTR to help the teams overcome their conservatism, and see that the changes have a clear and positive effect. "When we first showed the designs and the CFD to the teams, they all said, 'It's too big, it's too round, Ducati don't do it like that, Honda don't do it like that.'" Taylor related. "At the end of the second day of the test, we could show them the numbers from the airbox pressure measurements, a 10% increase in airbox pressure, and it's constant throughout the rev range." That data was enough to convince even the most hardened sceptic.
That change in attitude was necessary, as the FTR had undergone radical changes over the winter. "The one comment we had on the first day at Valencia, is all the other teams had said, the Suter had started their development from here, and had moved forward a bit. The Moriwaki was here, and had moved forward this much. The FTR was different. All our teams said 'We didn't realize that you would change as much as you have changed,'" Taylor said. "And we had a good base point, but we wanted to analyze it and see where we could move it forward," the FTR man continued, saying they had found a number of key areas. "Not little tweaks, but big steps. And these were not just changes we were making for the sake of changing things."
To get round the natural conservatism of the teams, FTR had also set up its own private test team, Taylor revealed, allowing them to pursue developments without worrying about the reactions of the teams, or having to rely on the feedback from the teams. "Testing with teams doesn't always produce good data, as they can have their own reasons for not liking a change, and will sometimes be looking for reasons to ditch it," Taylor said. "Having our own test team means we control the data, and the data it produces is neutral. We have a baseline and we can validate ideas against the baseline we have. We control it, we decide to what to test. We can then give the parts to the teams and they can decide for themselves whether they want to run them or not."