Interview: FTR's Mark Taylor on Aerodynamics and Air Intakes

The following interview was conducted with Mark Taylor of FTR Moto2 early in 2011. 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.

2010 FTR Moto2 bike
The 2010 FTR Moto2 bike, ridden by Jason DiSalvo at Indianapolis, with the thin intake

2011 FTR Moto2 bike
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."

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Nice interview, but why is it posted almost a year after it was taken? Most of this stuff is already outdated.

Why give your competitors your design information on new changes you are making? In Moto2 it's all about making the difference in chassis and aerodynamic design; as such you want to get some exclusive mileage out of an idea before other teams start copying it.

A year on, and this is no longer cutting edge and so they can talk about it. I'll bet there's stuff they're getting ready to add to the 2012 bikes that is being kept behind locked doors.

Also, I think he keeps articles like these for the "gaps" between action. It gives us something to discuss for awhile instead of passing through it during a race weekend.

Thanks for a great article.

I remember when I first saw their fairing with the big hole. My first thought was "wow, that makes a lot more sense, but if it is that simple why don't the factory bikes do it?"

Can the factories concern themselves that much with aesthetics to lose that much of an advantage even at this level? Or is there more to it than Mark Taylor would like to believe. I'm sure he's a hell of an engineer, but the resources he has is nothing compared to Honda engineering.

Maybe the factories are after more than just large volumes of air being packed into the air box, but more of a predictable and controllable flow at different speeds?

What Taylor has said is sensible, and entirely correct. The advantages of a lower area of boundary layer and a less turbulent airflow are obvious, and have been a feature of the LoPresti 'Howl Cowl' used on the Cessna Columbia (nee Lancair) for years - and the Columbia is one of the fastest piston-engined small planes in the world. The concept isn't as wonderful as LoPresti claims, but it does work.

"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."

Spoken like a true engineer..

Less FTRs in Moto2 this year suggests somebody's not happy with his pitch..I wonder why?

Aprilia made a pair of the best racing motorcycles ever, and it is much easier to loose HP on a RSA 125/250 that it is to make any extra. Aprilia had a 100 full time staff changing things by 0.25mm at a time. THAT is why nobody bothered touching the Aprilia is was already thought of, tested and proved by Jan Thiel himself. Nobody need concern themselves with 'improving' the Aprilia RSA you just have to ride it to it's potential.
It is also impossible to get 'more oxygen' through increased pressure, oxygen in the atmosphere is about 20.5% the world over at sea level. Higher airbox pressure just leads to increased dynamic compression.
Aero drag is good area to focus on though

I'm not sure I agree with you... that is the very concept of a turbo or super charger. Compress the air to get more oxygen molecules into the cylinder.

Also why you lose/gain horsepower due to altitude changes.

But, based on your previous knowledgeable posts, I know you know all that already... so maybe I am misunderstanding?

Ok, let's be clear about a few things.

First, increased pressure in the airbox doesn't give you more power, increased density does. Pressurizing the airbox increases the temperature as well as the density, so when you allow for 3% more pressure, you get about 2% more density, and hence about 2% more power.

Second, 3% extra pressure is about as much as you can do theoretically under ideal conditions, due to conservation of energy (ie you convert all of the kinetic energy of the incoming gas into pressure). So when he talks about 10% improvement, he is talking about 10% more of the less than 30millibars above atmospheric pressure, NOT increasing the absolute pressure in the airbox by 10% (100mbar). So we are talking about 0.3% increase in absolute pressure, hence 0.2% in density and power.

Third, since top speed increases as the third-root of maximum power, adding 0.2% of power will increase top speed by 0.13%, or about 0.35km/h or 0.1m/s. Hence it would take 40s to pull out from behind, draw level, pull a bike length in front and move back over. You'd need a rather long straight... No wonder the FTR power advantage doesn't seem to show up in the recorded top speeds.

In fact we are talking of a power advantage of about 0.002x90kW, or 180W. From memory, a cyclist who leaves the zip on his jersey halfway down burns an extra 10W at 50km/h, so that amount of drag would be 1.25kW at 250km/h. In other words, tight fitting leathers are likely to make a ten-times greater effect on top speed than the big-hole intake.

But I certainly agree that an FTR is more aerodynamic than a 1966 Matchless :)

Would a slight venturi effect somewhere in the length of the intake cause the air to expand slightly when entering the final space of the airbox, leading to a small drop in air temperature?

Not sure, just asking, but Boyle's law is pretty clear.

If you make the venturi just right... the pressure after will be almost the same as before, but lower in the middle. In practice, there will be boundary layer effects which will heat the air and dissipate the energy.

To get higher pressure without increasing temperature you'd need to feed the air through an intercooler. Really not worth doing and given the environment it's operating in, you'd be more likely to heat it than cool it.

BTW, the 2% density increase you get from ram air you could also get by lowering the temp in the airbox by 6°C... which is probably the best reason to have the air intake as far forward of the engine and radiator as possible :)

Backmarker thanks for the flowers :-) but it's still impossible to get more than 20.9% oxygen in earths atmosphere at any one time. What varies is the density or relative air density.Compressing the intake will increase pressure/density but not the available oxygen, like there will only ever be 100 cents in a dollar. The high veld at Kyalami required a specific set up and at sea level with Antarctic winds Phillip Island is great for HP(and seizing).

I saw an interesting pic of this years FTR..................................

If you have a container and fill it with air at 32psi you'll have more oxygen in that container than one filled at 16psi, even though the percentage of oxygen is the same. As you say, it increases the density. Density is mass/volume. If you increase the density while keeping the volume the same, you'll have more mass.

Yeah but that's not what you said originally. You said originally it's impossible to get more oxygen through increased pressure.

When in fact, it is. As has been said several times already, higher pressure -> higher density -> more oxygen per unit volume

And as was also pointed out... is how turbos and super chargers work.

I don't think anyone here would argue you can change nitrogen or CO2 to oxygen by increasing pressure.... only Jesus can do that.