10-16-2016, 12:30 PM
The Grand Prix Commission which oversees MotoGP racing has banned winglets, effective for the 2017 racing season. The decision was made back in June but hasn’t been well-publicized, and has hardly received any reasoned discussion in the motorsports media, mostly because the preponderance of motorcycle journalists are not familiar with subsonic aerodynamics and don’t really have much to add to the discussion. Another reason is that no data regarding winglet performance has ever been released to the press or public, for understandable reasons.
Manuel Pecino’s recent article in Sport Rider attempted to discuss the technology, and the reasons behind the ban, but as Mr. Pecino himself acknowledged, he is a layman and does not have a clear understanding of just what effect winglets would actually have on racing motorcycles.
Features like winglets sound plausible and appealing to the average person, but are really ineffective for road racing motorcycles when taken at their true engineering value. Underscoring this point, Marc Marquez reminded reporters at the Motegi press conference on October 14th that he did not use winglets at Aragon, and was apparently not planning to use them at Motegi. In his own words, “Already in Aragon I ride without winglets...it was the small ones in the fairing, but no difference.”
As Marc Marquez has learned first-hand, a professional evaluation indicates winglets can be problematic when used on a single track vehicle, as opposed to an airplane or automobile such as a Formula One racing car.
An analysis of the effect of winglets is very simple by today’s aerodynamic standards; these principles were first documented by the Wright Brothers using a home-made wind tunnel and later refined, and can be found on file with the National Advisory Committee for Aeronautics (NACA), formed in 1915.
By any standard, the winglets fitted to MotoGP motorcycles are extremely crude devices more akin to air brakes, and are bound to create as many, if not more, problems than they might solve. If we examine the two benefits cited by Mr. Pecino, as explained to him by others, we can find the problems after reviewing the well-known aerodynamic effects of a crude airfoil on a moving object.
The first of these benefits is ostensibly additional downforce, which delays, reduces, or eliminates the onset of power reduction by the motorcycle’s ECU to reduce front-wheel lift. There are two aspects of this feature that have to be understood from both an aerodynamic and engineering perspective. First is the basic rule of energy; you can’t get something for nothing. Any airfoil creates drag in proportion to lift. Thus, the negative lift, or downforce, created by the winglets is accompanied by a fair amount of drag, which the motorcycle’s engine must overcome.
While the winglets do create negative lift, the thrust needed to overcome the drag of the winglets themselves amounts to a certain amount of horsepower. How much? Without knowing the area of the winglets, efficiency of the design, and angle of attack, it’s hard to say. Assuming a coefficient of lift of 0.8, and a winglet area of 1.5 square feet, the downforce would range from about 30 pounds at 100 mph to 140 pounds at 215 mph. Induced drag adds around 15% to those figures. This is for the winglets alone; figuring in turbulence and other parasitic drag, the net loss in power available for thrust is perhaps 1-2 horsepower. But the number could be quite a lot higher depending on design factors, perhaps as much as 15-20 horsepower at top speeds. Consider the last two wins by Honda; both Dani Pedrosa and Marc Marquez won either without any winglets (Pedrosa, at Misano) or with only the smallest vestigial version fitted (Marquez, at Aragon). Suzuki’s Maverick Vinales won Silverstone handily with only vestigial winglets. Both empirical evidence and aerodynamic analysis strongly suggest any benefit to acceleration imparted by winglets is offset by other factors created by their presence, including drag and turbulence.
Pecino’s article also relates that both braking and cornering are improved by the downforce of winglets, according to his sources. A review of the aerodynamics at play actually reveals unpredictable and perhaps undesirable results.
The first of these, braking, is said to be enhanced because the winglets increase the downforce on the front tire, thus expanding the size of the contact patch and increased the available braking forces.
As might be guessed by anyone familar with braking at the limit (rear tire off the ground), there is only a certain amount of braking available, and the rider is able to bring all of that to bear through direct control inputs, by applying the front brake and putting up to 100 percent of the bike’s weight on the front tire. The rider can then modulate the lever to extract the maximum braking available for any given set of conditions. Rider skill and judgment are all that are needed to achieve maximum braking, and well beyond. With up to 150 pounds of downforce, the winglets will reduce the lever pressure needed at high speeds on first application of the brakes, rather like a backseat rider. But as the speed rapidly decreases, the effect of the downforce is dramatically reduced because lift and drag are proportional to the square of the speed. Rolling off the throttle with these “airbrakes” fitted at high speeds results in a much quicker initial deceleration than if they were not fitted. The “helping hand” provided by the winglets’ downforce at 200 mph is reduced to one-fourth that amount at 100 mph. This is not a linear control input, and is completely undesirable when trying to line a racing motorcycle up for a turn and modulate the brakes as the rider enters the corner.
Some of these corners are taken well into triple-digit speeds, which creates yet another control issue, again detrimental to both the bike’s handling and the rider’s sense of fine control.
An airfoil creates only downforce when level with the horizon. But when banked, it creates both a side force and downforce. This is how an airplane turns. These forces are roughly equal. At 100 mph, the forces created by a set of winglets are substantial. When banked at 50 degrees, about half that force is trying to push the motorcycle laterally off the racetrack, to the outside of the turn. The other half is putting pressure on the contact patch of the front tire. The rider has to compensate for these forces by countersteering and hanging off the motorcycle to an extreme degree. Again, it’s the analogy of an “unseen hand” and unwanted crosswind interfering with rider control, and at maximum lean (which can exceed 60 degrees at times) the last thing the rider needs is an additional crosswind force as created by those winglets.
Anyone who watches MotoGP racing regularly has see many unexplained lowsides where the rider simply lost the front for no apparent reason. At Motegi this past weekend, both Jorge Lorenzo and Valentino Rossi crashed out of the October 16th race due to inexplicable lowside events. The Yamaha chassis is known to be more sensitive to front-end setup, which gives it better mid-corner speed but creates issues with corner entry and initial loading of the front contact patch. The Honda, with its V4 engine, is set up to be steered more like a dirtbike, especially for Marquez, and is less susceptible to this. Look to the winglets for the possible source of the problem. On the knife-edge of control at maximum lean, the few extra pounds of lateral and down forces can mean an unexpected loss of traction. The calculations clearly show this.
On top of the control problems and negative effects created by these winglets, there is also the issue of wake turbulence, and the obvious safety issues created by having a pointed or edged shape attached firmly to the front of the motorcycle.
The riders do not need aerodynamic aids to help them manage the motorcycle. Controlling the bike’s direction and velocity is their job and that’s why they must be exceptional athletes. As anyone who’s spent time riding a racetrack at high speeds knows, it’s an exhausting task, even at a track day level.
Road racing motorcycles are not airplanes, and their single-track configuration does not lend itself to aerodynamic solutions other than effective streamlining and the routing of intake and cooling air flow. Beyond those features, the efficiencies must reside in the chassis, engine, and tire design as well as the ECU and control interfaces. In the last analysis, it’s the rider’s job to make it all work.
Manuel Pecino’s recent article in Sport Rider attempted to discuss the technology, and the reasons behind the ban, but as Mr. Pecino himself acknowledged, he is a layman and does not have a clear understanding of just what effect winglets would actually have on racing motorcycles.
Features like winglets sound plausible and appealing to the average person, but are really ineffective for road racing motorcycles when taken at their true engineering value. Underscoring this point, Marc Marquez reminded reporters at the Motegi press conference on October 14th that he did not use winglets at Aragon, and was apparently not planning to use them at Motegi. In his own words, “Already in Aragon I ride without winglets...it was the small ones in the fairing, but no difference.”
As Marc Marquez has learned first-hand, a professional evaluation indicates winglets can be problematic when used on a single track vehicle, as opposed to an airplane or automobile such as a Formula One racing car.
An analysis of the effect of winglets is very simple by today’s aerodynamic standards; these principles were first documented by the Wright Brothers using a home-made wind tunnel and later refined, and can be found on file with the National Advisory Committee for Aeronautics (NACA), formed in 1915.
By any standard, the winglets fitted to MotoGP motorcycles are extremely crude devices more akin to air brakes, and are bound to create as many, if not more, problems than they might solve. If we examine the two benefits cited by Mr. Pecino, as explained to him by others, we can find the problems after reviewing the well-known aerodynamic effects of a crude airfoil on a moving object.
The first of these benefits is ostensibly additional downforce, which delays, reduces, or eliminates the onset of power reduction by the motorcycle’s ECU to reduce front-wheel lift. There are two aspects of this feature that have to be understood from both an aerodynamic and engineering perspective. First is the basic rule of energy; you can’t get something for nothing. Any airfoil creates drag in proportion to lift. Thus, the negative lift, or downforce, created by the winglets is accompanied by a fair amount of drag, which the motorcycle’s engine must overcome.
While the winglets do create negative lift, the thrust needed to overcome the drag of the winglets themselves amounts to a certain amount of horsepower. How much? Without knowing the area of the winglets, efficiency of the design, and angle of attack, it’s hard to say. Assuming a coefficient of lift of 0.8, and a winglet area of 1.5 square feet, the downforce would range from about 30 pounds at 100 mph to 140 pounds at 215 mph. Induced drag adds around 15% to those figures. This is for the winglets alone; figuring in turbulence and other parasitic drag, the net loss in power available for thrust is perhaps 1-2 horsepower. But the number could be quite a lot higher depending on design factors, perhaps as much as 15-20 horsepower at top speeds. Consider the last two wins by Honda; both Dani Pedrosa and Marc Marquez won either without any winglets (Pedrosa, at Misano) or with only the smallest vestigial version fitted (Marquez, at Aragon). Suzuki’s Maverick Vinales won Silverstone handily with only vestigial winglets. Both empirical evidence and aerodynamic analysis strongly suggest any benefit to acceleration imparted by winglets is offset by other factors created by their presence, including drag and turbulence.
Pecino’s article also relates that both braking and cornering are improved by the downforce of winglets, according to his sources. A review of the aerodynamics at play actually reveals unpredictable and perhaps undesirable results.
The first of these, braking, is said to be enhanced because the winglets increase the downforce on the front tire, thus expanding the size of the contact patch and increased the available braking forces.
As might be guessed by anyone familar with braking at the limit (rear tire off the ground), there is only a certain amount of braking available, and the rider is able to bring all of that to bear through direct control inputs, by applying the front brake and putting up to 100 percent of the bike’s weight on the front tire. The rider can then modulate the lever to extract the maximum braking available for any given set of conditions. Rider skill and judgment are all that are needed to achieve maximum braking, and well beyond. With up to 150 pounds of downforce, the winglets will reduce the lever pressure needed at high speeds on first application of the brakes, rather like a backseat rider. But as the speed rapidly decreases, the effect of the downforce is dramatically reduced because lift and drag are proportional to the square of the speed. Rolling off the throttle with these “airbrakes” fitted at high speeds results in a much quicker initial deceleration than if they were not fitted. The “helping hand” provided by the winglets’ downforce at 200 mph is reduced to one-fourth that amount at 100 mph. This is not a linear control input, and is completely undesirable when trying to line a racing motorcycle up for a turn and modulate the brakes as the rider enters the corner.
Some of these corners are taken well into triple-digit speeds, which creates yet another control issue, again detrimental to both the bike’s handling and the rider’s sense of fine control.
An airfoil creates only downforce when level with the horizon. But when banked, it creates both a side force and downforce. This is how an airplane turns. These forces are roughly equal. At 100 mph, the forces created by a set of winglets are substantial. When banked at 50 degrees, about half that force is trying to push the motorcycle laterally off the racetrack, to the outside of the turn. The other half is putting pressure on the contact patch of the front tire. The rider has to compensate for these forces by countersteering and hanging off the motorcycle to an extreme degree. Again, it’s the analogy of an “unseen hand” and unwanted crosswind interfering with rider control, and at maximum lean (which can exceed 60 degrees at times) the last thing the rider needs is an additional crosswind force as created by those winglets.
Anyone who watches MotoGP racing regularly has see many unexplained lowsides where the rider simply lost the front for no apparent reason. At Motegi this past weekend, both Jorge Lorenzo and Valentino Rossi crashed out of the October 16th race due to inexplicable lowside events. The Yamaha chassis is known to be more sensitive to front-end setup, which gives it better mid-corner speed but creates issues with corner entry and initial loading of the front contact patch. The Honda, with its V4 engine, is set up to be steered more like a dirtbike, especially for Marquez, and is less susceptible to this. Look to the winglets for the possible source of the problem. On the knife-edge of control at maximum lean, the few extra pounds of lateral and down forces can mean an unexpected loss of traction. The calculations clearly show this.
On top of the control problems and negative effects created by these winglets, there is also the issue of wake turbulence, and the obvious safety issues created by having a pointed or edged shape attached firmly to the front of the motorcycle.
The riders do not need aerodynamic aids to help them manage the motorcycle. Controlling the bike’s direction and velocity is their job and that’s why they must be exceptional athletes. As anyone who’s spent time riding a racetrack at high speeds knows, it’s an exhausting task, even at a track day level.
Road racing motorcycles are not airplanes, and their single-track configuration does not lend itself to aerodynamic solutions other than effective streamlining and the routing of intake and cooling air flow. Beyond those features, the efficiencies must reside in the chassis, engine, and tire design as well as the ECU and control interfaces. In the last analysis, it’s the rider’s job to make it all work.
