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2008 Qatar FP3 Day 2 - Rossi Finds Some Pace

Once again it was Casey Stoner who was fastest during the early session of Free Practice, ahead of this evening's official qualifying session. And once again, it was Jorge Lorenzo who was second fastest, just as the Spaniard was last night. But behind Lorenzo was his team mate and seven-time world champion Valentino Rossi, who took nearly 8/10ths off his previous fastest lap time.

More importantly, it wasn't all the Stoner Show this session, with Valentino Rossi and Jorge Lorenzo both holding top spot during the session, albeit briefly. Stoner is obviously fast right from the off, but others seem to be improving behind him.

Alex de Angelis was the other rookie to be quick, finishing in 4th, and giving Bridgestone 3 of the top 4 spots. The Bridgestone tires are quicker in the earlier part of the evening, when the track still has some heat left in it, but get worse in the depths of night. Which is unfortunate for the men on Japanese rubber, as that is when the race is due to be won.

With Andrea Dovizioso in 6th, the first factory Honda is Dani Pedrosa in 7th place, forced to see two satellite Hondas ahead of him. But Pedrosa is faring better than his team mate, as Hayden is languishing down in 15th spot, ahead of Marco Melandri, who must be wondering what he's doing wrong.

Qualifying begins at 11pm local time, when more will be revealed.

Pos. No. Rider Manufacturer Fast Lap Diff Diff Previous
1 1 Casey STONER DUCATI 1'55.186
2 48 Jorge LORENZO YAMAHA 1'55.299 0.113 0.113
3 46 Valentino ROSSI YAMAHA 1'55.598 0.412 0.299
4 15 Alex DE ANGELIS HONDA 1'55.659 0.473 0.061
5 5 Colin EDWARDS YAMAHA 1'55.746 0.560 0.087
6 4 Andrea DOVIZIOSO HONDA 1'55.788 0.602 0.042
7 2 Dani PEDROSA HONDA 1'55.902 0.716 0.114
8 7 Chris VERMEULEN SUZUKI 1'56.108 0.922 0.206
9 14 Randy DE PUNIET HONDA 1'56.371 1.185 0.263
10 52 James TOSELAND YAMAHA 1'56.467 1.281 0.096
11 21 John HOPKINS KAWASAKI 1'56.472 1.286 0.005
12 65 Loris CAPIROSSI SUZUKI 1'56.516 1.330 0.044
13 56 Shinya NAKANO HONDA 1'56.741 1.555 0.225
14 24 Toni ELIAS DUCATI 1'56.789 1.603 0.048
15 69 Nicky HAYDEN HONDA 1'56.971 1.785 0.182
16 33 Marco MELANDRI DUCATI 1'57.658 2.472 0.687
17 13 Anthony WEST KAWASAKI 1'57.777 2.591 0.119
18 50 Sylvain GUINTOLI DUCATI 1'57.800 2.614 0.023

Hayden And Pedrosa To Use 2007 RC212V At Losail?

After Honda got their predictions of how to build a title-winning 800cc MotoGP bike so utterly wrong in 2007, expectations were raised that they would not make the same mistake again in 2008. If there was ever a year that you might expect HRC to come out with an unbeatable factory bike, surely this would be it.

Apparently, those expectations are also wide of the mark, for this afternoon, at Losail, Repsol Honda staff were spotted by our Italian counterparts GPOne.com unpacking the parts for 2007 RC212Vs from flight cases, and cleaning them ready for use. The initial diagnosis is that HRC will be testing the 2007 bikes during Friday's free practice sessions, pitting them up against the 2008 bikes to see which is faster.

Such a decision would be a remarkable implicit admission by HRC that their new bike is just not up to scratch yet. However, there are a few mitigating circumstances: the new factory RC212V suffered serious problems with grip during the night tests last week at Losail, as the cool track temperatures played havoc with traction. With no burning desert sun to warm the track, track temperature remains stubbornly around air temp, which is falling to around 10-15 degrees Centigrade out in the desert. The problem was highlighted by the fact that on race tires, the satellite Hondas - all basically running a version of the 2007bike which was victorious at Valencia - were significantly quicker than the factory Repsol bikes during the tests under the floodlights.

Although remarkable, the choice to revert to the previous year's bike would not be unique: in 1984, "Fast" Freddie Spencer elected not to run the brand new V4 Honda 500 at the German GP, choosing instead to go out on the older V3 design. Spencer claimed both the pole and the win that race, a fact which may help allay any qualms held by Nicky Hayden or Dani Pedrosa.

~~~ UPDATE ~~~

The story has just been confirmed by Motorcycle News. MCN's Matthew Birt is saying that Hayden will definitely be running the 2007 RC212V, while Pedrosa is as yet undecided.

Rusty Writes: Musco, Lighting Up The World of Sports

For those of you who did not recently watch the Daytona 500 here in The States, you missed your best opportunity to see the handiwork of Musco Lighting prior to the GP of Qatar. Musco has been the premier outdoor lighting specialists in The States for 32 years. I first heard of them 23 (or more) years ago while I was marching in drum & bugles corps on American and Canadian football fields. For three years in the mid '80s, the annual Finals competitions were held in Madison, WI. Musco is from nearby (relatively speaking) Iowa, and there was quite a discussion about their amazing ability to use temporary lighting stands to illuminate the somewhat large Camp Randall Stadium that played host for the Finals. At the time, that stadium did not have permanent lighting. Musco was beginning to be known for showing up at a football stadium with their large trucks and providing enough light for a live television broadcast where such a thing had not been previously possible at night.

A few years later they pioneered a plan to light large oval racetracks known here as "superspeedways". NASCAR superspeedways are generally more than 1 mile around and often feature turns sufficiently banked so as to resemble a velodrome or the inside of a bowl. Because of this, the power of their engines, and their aerodynamic designs, the top-tier cars could average over 200 mph every lap on the largest and most-banked tracks - if the sanctioning body would allow it. Oval tracks are all around the American map, and smaller tracks have been lit with more conventional overhead lighting for decades. But these smaller tracks do not feature race cars approaching the speeds of the larger tracks, and they do not need to look good for a national television audience.

The event that changed the course of motor sports history was held at the Charlotte Motor Speedway in May of 1992. I happened to have visited there about a month before the race and got a little inside information on what to expect. The event was the NASCAR "all-star" sprint race, then called The Winston. It was such a success (and looked spectacular on television), that over the next few years, more speedways purchased similar lighting arrangements. Eventually a plan was developed to envelope the 2.5 miles that are Daytona (Charlotte is 1.5 miles around), and the first night race there was scheduled for the Summer of 1998.

It took much less time to realize the advertising potential of special "night race" liveries. The cars that already featured the more exotic colors looked especially brilliant under the lights, so new, more eye-catching paint schemes were quickly imagined for subsequent night races.

The key to their innovation was at the ground level. Naturally, overhead lights had been around a long time, but to eliminate shadows and dark gaps, a method of lighting the track from the infield without blinding the drivers was also necessary. The invention is ingenious and must be seen to be fully appreciated, but essentially, the lights (in the original design) are on the ground and shine up into mirrored boxes that are carefully arrayed to light the track without putting a glare in the drivers' eyes. The result is a beautiful, brightly lit track with no shadows, where a driver would have to go the wrong direction to be blinded by these infield lights. These devices came to be known by their product name "Mirtran", once Musco developed an enclosure that housed the mirrors, blinders, and light fixture all in one box. These are now what you will see making long-throw, tight beams of light that seem to emanate from relatively short posts (reportedly as "short" as 3 metres at Losail).

As ingenious as the original design is, it is admittedly less difficult to light a bowl-shaped track where the racing surface is banked toward the infield. American Stock cars, like Touring series cars in the rest of the world, have roofs the keep overhead lights out of the drivers' eyes. In addition, a race car driver's head is kept at a relatively constant height. For a road course that is - literally - desert flat and features right and left turns that double back on themselves, Musco has a much more complex array of variables to manage. The ever-changing altitude of the riders' heads from as high as 1.5 meters to probably less than .5 meter (in Toni Elias' case) must be factored into the design of the arrays. They will have to calculate every conceivable line of sight on or near the track and ensure that there is no reasonable way that a rider could end up looking into one of the light boxes while still on his motorcycle.

In staring at a map of the Losail Circuit, it was not obvious to me how they're going to do it. But I certainly trust Musco's engineering ability to make this new challenge stunningly beautiful. I had hoped to establish a connection with a company spokesman or engineer to inquire about some of the specific challenges involved in this project, but alas, I do not appear to have large enough credentials to warrant having my phone calls returned.

Now that the test sessions have completed and photos are available, I must say that I am slightly surprised by what I see. Considering what I have gotten used to here in The States, some of these pictures strike me as a little dark, which concurs with the reports from the riders. In some shots, one can see just how far these beams of light are traveling to reach their intended section of tarmac. Naturally, camera placements are critical to what we see, and artificial lighting can wreak havoc on previously ideal locations. Hopefully the various camera crews are hard at work this week finding the best new perches and are not just resting on their laurels. As an American, spoiled by the NASCAR experience, I have high expectations for what we all will see on television this weekend and in the ensuing photos. I imagine, if things appear as they should, most of the bikes will have special liveries for future night racing. And that just might be a bigger story than the actual race.

Nicky Hayden's 2006 Championship Leathers For Sale

Dean Adams, the driving force behind the outstanding Superbikeplanet.com website, is auctioning off some of the motorcycle racing memorabilia he has collected over the many years he has been working as a journalist, the proceeds of which go to the Merlyn Plumlee scholarship fund. The fund was set up after the sad demise of Merlyn Plumlee, the former Honda AMA crew chief, widely touted as one of the best ever to wield a clipboard and spanner.

The latest item to be auctioned off is a unique piece of MotoGP history: a set of leathers worn by 2006 MotoGP world champion Nicky Hayden during his championship campaign. The leathers are signed by Hayden, who won the AMA Superbike title with Plumlee in his garage. Current bidding (as of February 28th) stands at $3,380, which given the continuing weakness of the US Dollar, is a real bargain for a European racing fan. The auction is due to run until March 9th, so you still have plenty of time to obtain a remarkable keepsake.

Adams will be auctioning off several more items over the course of the year, so keep an eye out for his other items on eBay.

Guest Column - Why Big Bang Engines Work

The piece we ran by Sean McConnell on an alternative approach to big bang engines kicked up quite a lot of debate about the merits of big bang engines vs screamer firing orders. As luck would have it, this week's episode of Bob Hayes' utterly outstanding MotoGPOD podcast featured an excellent discussion on the history and theory of big bang engines by Scott Jones. The segment was so well-written that we asked Scott if we could run it here, as a counterpoint to Sean's article. Scott, whose outstanding photos of the 2007 Laguna Seca race we were privileged enough to show last year, graciously allowed us permission.

We think this is one of the best explanations of how, and more importantly, why big bang engines work we have seen. We hope you agree.

Why Big Bang Engines Work

By Scott Jones

One way to look at MotoGP is as a continuing struggle to balance ever-increasing horsepower with a contact patch about the size of a compact disk. While common sense says that tire technology and suspension tuning have the most influence over where the limit of traction lies, for the last two and a half decades an element of internal engine architecture has had a profound effect on rear wheel traction and overall rideability.

MotoGP fans hear the big bang engine mentioned frequently, but what is it, and why does it improve a rider's control? The first question is easily explained. The second is not.

The idea behind the big bang engine is to move the pistons closer together around the crankshaft and make them fire in quick succession, rather than every 180 degrees as in an engine with a rational firing order. And instead of firing each cylinder individually, you fire two cylinders at a time, creating two large bangs per firing cycle instead of four smaller ones. The concept has its roots in flat track racing, where Harley big-bang V-twins dominated for decades. The premiere class saw big bang engines in Suzuki test bikes in the early 1970s. Cagiva tried their Bombardone engine in the mid 1980s, but it was Honda that made the big bang design an integral part of road racing with their 1992 NSR500. With this bike, Mick Doohan handily won the first four races of the season and would likely have run away with the championship had he not crashed so badly in practice at Assen and missed the next four races.

When Honda unveiled their big banger in 1992, the sound was dramatically different from the rest of the bikes on the grid. Other manufacturers brought audio analyzing equipment to the track to figure out what Honda was doing differently. The audio trick worked and soon afterward, the other teams were playing catch up, both on and off the track, putting their own big bangers into development to compete with the NSR500.

In the modern era, however, one can no longer tell for sure just by an engine's sound if it's a big banger or a rational firing order screamer. The many technological advances MotoGP has seen since the early 1990s have removed the distinct audible difference of this engine design. Engineers now choose inline or V layouts; single or multiple crankshafts; spring, mechanical or gas-powered valves; and so on, and each manufacturer must decide if a big bang layout works better with their other design choices than a rational firing order. The 2007 season saw bikes on both sides of this fence. One company even switched sides in the middle of the season! This is the protean nature of MotoGP: the bikes are always changing as teams search for whatever combination of technology will produce even a slight advantage.

But as development of the big banger continued in the 1990s, engineers had to determine what degree of separation was optimal for the overall engine architecture. For example, the first responses to the 1992 NSR500 were said to be a Cagiva that fired its pistons 66 degrees apart and a Suzuki that found 15 degrees to be the magic number. The only constant was that big bang engines, combined with the technologies of the day, made for lower lap times even as some very clever people wondered why this design made such a big difference to a bike's rideability.

Given nature's bias against things that are out of balance, the big bang engine is a crazy idea that should create more problems than it could possibly solve. You may remember the right hand rule from basic physics. Imagine an engine's crankshaft spinning in its case and turn your right hand in the same direction the crankshaft is turning. If you extend your right thumb, you have just identified a vector, or gyro effect, that the spinning crankshaft is generating.

The faster a crankshaft is spinning, the stronger that vector is and the harder it is for the rider to turn the bike away from that vector. Dual crankshaft engines produce a better handling motorcycle by reducing the engine's internal gyro effects. But adding a heavy, throbbing big bang to the firing cycle complicates this situation with its lopsided pulse. Such imbalance, especially in machines with as many moving parts as a motorcycle engine, usually leads to unwanted vibrations, which lead to inefficient function, which leads to loss of power, which leads to decreased performance and slower speed. Then add to the equation that the increased torque from the double piston firing and the close proximity of the timing requires a heavier, stronger crankshaft, bearings and gears. You have a heavy, less efficient, imbalanced engine making fewer horsepower than the engine with the rational firing order. But this big banger just happens to have the advantage of increased rideability.

And sometimes a given advantage is significant enough to outweigh its disadvantages. Loss of power is one thing, but as we know, MotoGP bikes have more power than they can efficiently use. With power to spare, some vibration in the right place just might be a good thing.

It is, according to a 1992 article by Kevin Cameron, who explained the big bang engine's benefit as an effective compensation for the increasing grip found when radial tires replaced bias-ply tires. Remember those amazing high side crashes we used to see so often with the 500s? The frequency of high sides reached a peak with the introduction of radial tires because the radials would grip like crazy until a certain point, then suddenly break loose, only to grip again just as suddenly a split-second later. This process happened faster than a rider's perception could detect it, which meant that one moment he was riding at the limit and the next he was flying over the handlebars. With bias-ply tires, the transition from full grip to full sliding was gradual, and the rider could feel the limit of traction approaching as the rear end of the bike started to hang out more and more. With the new radial tires, however, by the time he found the limit of traction it was too late.

But how can the firing scheme of the engine give the rider better feedback about rear tire grip? There are at least two theories about this.

One theory suggests that while human perception is much too coarse to tell one millisecond from another, a MotoGP tire endures its very stressful and very short life being profoundly affected by many forces, one distinct millisecond to the next. Not only is gravity forcing the tire against the road surface, but as the bike is leaning from side to side the tire is fighting severe lateral pressure. The bike is also braking frequently and, most importantly for this discussion, accelerating with tremendous power.

Under acceleration, the aforementioned milliseconds 'feel' different to the tire because it senses each rotation of the crankshaft not as one steady force but as an ever-changing pressure. As a cylinder fires, for a very brief moment that force pushing the tire forward is at its most intense. But quickly that force decreases as the piston slows down a bit on its way to the bottom of its stroke. Once there, it reverses direction and heads back up on the exhaust stroke. If no other pistons were involved, it would continue to slow down on the intake and compression strokes until the next ignition forced it to accelerate again. When you fire pistons individually and every 180 degrees of crankshaft rotation, the rear tire feels a cumulative affect of these brief forces of acceleration as a relatively regular and steady pressure - good for times when conditions are ideal, but bad when, say, the power of the engine combines with other factors to cause a loss of rear tire grip. The tire suddenly breaks free of its grip and spins until grip returns, which it always does, and often so suddenly that the rider experiences a high side.

Instead of the rational firing order's more even pressure under acceleration, a force that makes the tire grip grip grip until it suddenly breaks loose, the big banger delivers huge, torque-filled pulses due to two cylinders firing right before the other two cylinders. The engine's entire power cycle is compressed into a brief double pulse that at high revs momentarily overcomes the tire's grip and causes a very brief slip. After the double bang, the tire recovers its grip as the pistons decelerate and progress toward the next combustion strokes. This first theory says that the series of ultra-brief slips creates a unique situation when exiting turns. As revs climb, lateral forces on the tire cause these micro slips to become sideways movement of the bike's rear end. The rider can use this gradual increase in lateral slippage to sense the limit, just like he could with a bias-ply tire's gradually increasing slippage. Thus the big bang engine makes a radial tire mimic the best quality of a bias-ply tire, its gradual slipping as it approaches the final limit of traction.

This was the theory back in 1992 when Cameron explained the big bang engine's benefits in Cycleworld. It was also thought that compressing the timing of all combustion strokes gave the tire rubber time to rest up between big bangs and thus maintain top performance longer into the race. But as recently as November, 2007, Michael Scott wrote: "The tire people have yet to understand why a syncopated drumbeat of firing intervals should be easier on their rubber than the steady, even pulse of an inline four, but it is clearly so." After many years of considering why the big bang engine delivers its undeniable benefits, some very clever people are still wondering exactly why it works.

Which brings us to a more current theory, that of Yamaha's chief engineer, Masao Furusawa. At the end of the 2007 season, Furusawa gave a presentation in which he explained his theory of the big banger's benefits in terms of the engine's internal harmonics. Instead of reintroducing gradual lateral slipping to help the rider sense the limit of grip, the quick dual pulses of the big bang engine create a much different harmonic state during acceleration.

Just as the tire in the previous theory can sense subtle differences in the forces of the accelerating and decelerating piston, the crankshaft in Furusawa's theory creates a noticeably different harmonic signature when the pistons are fired in close succession.

Again we are dealing with milliseconds and distinct changes in the movement of various engine parts during those very brief periods. Friction causes the piston to decelerate after combustion, and so does the necessity of reversing direction when the piston approaches top dead center and bottom dead center. Again, think back to beginning physics and how something moving in a given direction at a given velocity wants to keep doing just that. After ignition, the piston is moving very quickly down the bore until it reaches the limit imposed by the connecting rod. Rather suddenly it is forced to stop, and then head in the opposite direction. As it is moving down the bore, it has considerable inertia and kinetic energy, both of which have to be accounted for as part of the reverse of direction. Both forces are absorbed by the crankshaft, something Furusawa called 'inertia torque' to differentiate these forces from combustion torque, the force created by the ignition of the fuel mixture.

Just as wind resistance increases exponentially as speed climbs, so inertial torque increases as the revs climb. So while inertia torque is a factor in your road bike, you don't operate its engine at sufficient revs to notice a problem. But MotoGP engines run fast enough that inertia torque becomes a very noticeable problem indeed.

To explain just how this problem manifests itself on the track, Furusawa used the metaphor of tuning a radio. As you turn the dial searching for the desired station, you hear the noise of signal interference decrease as you approach a spot where the signal strength is at its peak. The noise is still there, but the interference is low enough that you hear a clear signal. In Furusawa's metaphor, the rider is using the throttle to tune in a good signal to the rear tire. If there is too much noise between the throttle and the tire, the rider doesn't sense a strong signal and has little notion of where the limit of traction lies. If the interference is low enough, the rider has a good connection to the tire via the throttle and can get closer to the limit of traction.

Inertia torque is noisy, and thus interferes with the rider's ability to tune in a good signal. Enter the big banger, which reduces the periods of inertia torque by compressing the firing pattern. As the crankshaft is absorbing inertia and kinetic energy from the pistons and connecting rods, it's doing so in a smaller window of its revolution. The result is a longer period of each revolution that is noise free, or relatively so, giving the rider a stronger signal between the throttle and the rear tire.

In spite of their troubled 2007 performance, Yamaha had done much testing of different big bang engine schemes, and according to Furusawa, all results backed up his inertia torque theory. Is the big banger question answered once and for all? Maybe, and maybe not. Scientific history is full of explanations that were accepted one day, only to be refuted with more complete data the next. That two such experienced and clever individuals as Kevin Cameron and Masao Furusawa have had such different ideas about why the big bang design works suggests that we may never know, in any definitive way, the big banger's secret. Given, the two theories presented here are decades apart, and the older theory is based more on speculation than on testing data. But Michael Scott's recent remark about the tire people still not knowing why the big banger is easier on their tires makes plain that there are still big bang mysteries to be solved. We may never know everything, because the dominant package in MotoGP last year was a screamer, not a big banger.

In spite of the big banger's successes since 1992, it has not always been the design of choice in the premier class. As a prototype series, MotoGP finds its engineers constantly re-evaluating older technologies as new ones arrive on the scene. The big bang engine is no exception, and it has come and gone according to influences such as continued tire development and rule changes. The switch from two-stroke to four-stroke engines was a major reset for designers, and the early 990cc engines were for the most part screamers as engineers sought maximum horsepower to complete with the holdover 500cc two-strokers in 2002. But when Ducati announced it would enter the premiere class, it went back to the big bang engine right away. In February 2002, Ducati Corse Director Claudio Domenicali explained the decision like this:
"...further analysis led us to decide that the best solution was a 'double twin' and therefore we designed an engine with four round pistons which, thanks to a simultaneous two-by-two firing order, reproduces the working cycle of a twin. This will generate the 'big bang' effect, making the rear tire work in a way that extends its duration and improves rider feeling when exiting curves."
While that first MotoGP Ducati showed promise, it wasn't until Ducati replaced their big bang engine with a screamer in the 800cc GP7 that they won the world championship.

Ever since 1992, engineers have faced the dilemma: more horsepower at the expense of rideability with a screamer engine, or less power with an advantage when exiting corners with a big banger? Again, each new technology must be taken into account in the search for the current season's best solution. When pneumatic valve systems entered the scene and offered higher revs and more power, once again teams had to re-evaluate the screamer-big banger question. As tires improve, teams must decide if this year's rubber is good enough to allow the abandonment of big bang engines. The big bang pendulum swings back and forth. Sometimes teams reveal their choices, and sometimes they don't. Ducati announced that the GP7 would be a screamer when the bike was revealed at the beginning of the season. Kawasaki announced that their 2005 engine would be a big banger as part of that bike's introduction. Yamaha switched to a big banger in 2004 but didn't publicly confirm this choice until the 2007 season ended. In a recent interview on GPone.com, Randy Mamola said that Honda switched from a big banger to a screamer during the 2007 season. This was likely due to the lack of power relative to the Ducati at the beginning of the year. Honda continued to push the last spring-valved engine in MotoGP to its probable limit of performance, and by the end of the year had the engine Ducati feared most.

So what will we see in 2008? Honda's testing of their new pneumatic-valved engine has not been the success they were hoping for, and it looks like Hayden and Pedrosa will begin the season on last year's spring-valved screamer until HRC can get the required power from the newer technology.

From Furusawa's presentation, it seems clear that Yamaha will stay with a big banger for its harmonic superiority, though in the aforementioned GPone.com interview, Mamola speculated that Yamaha will certainly offer Rossi a screamer at some point if their current package continues to lag behind more powerful engines.

Ducati will almost certainly stay with an updated version of its GP7 screamer. Suzuki seems content with their big banger, but 12 weeks after the Valencia test, teams went to Sepang, where Kawasaki, a big bang proponent since 2005, made news by testing a screamer engine. A team spokesman would not admit that the team is moving away from the big bang engine for competition, saying that this was a test of 'other technologies.'

Other technologies are always a complication. Honda proved that the big banger was the right way to go in 1992. The dramatic change in tires when radials replaced bias-ply tires made the big bang engine a success, regardless of exactly why the different firing scheme worked. But other technologies happen, and something as significant as a fundamental change in tire construction has arrived that may very well make the big banger a thing of the past: electronic control of power delivery. Ducati's electronics package is said to combine GPS data (to tell the computer exactly where the bike is on the track) with live lean angle information so the computer knows just what the bike is doing and can control the engine's output accordingly. Computer-controlled engine mapping is now done not only on a gear-by-gear basis, but also on a corner by corner basis. As electronics get more and more sophisticated, the rider gets more and more help controlling the power, which is just what the big bang engine is supposed to do at the expense of added weight and lower horsepower.

So Kawasaki was using a screamer to test other technologies, rather than considering a switch from big banger to screamer for competition? Does a team need to admit that it would like more horsepower if their electronics allowed their riders to get that extra power to the ground? It seems that a screamer test is more likely a test of the team's electronics, to see if the current computer package is capable of taming the added power the rational firing order produces. Or, in Furusawa's terms, is the new software sophisticated enough to overcome the signal noise generated by inertia torque and give the rider a good throttle-to-rear tire connection?

So the big banger's future is far from certain. Advancing electronic control of power delivery could spell its demise. Or, something like the recent spec tire and spec ECU threats could become reality, forcing teams to abandon the allure of the screamer's greater power and return to big bang engines. The only thing that is certain is that MotoGP will continue to change as engineers search for even a slight advantage of technology. For the foreseeable future, at least, the big bang engine will certainly be one of the many factors they will consider.

Scott Jones is a photographer and writer. You can see more of his photographs over at http://www.turn2photography.com/, or read his blog over at http://blog.scottjones.net/. You can contact him via his website.

Guest Column - Why Big Bang Engines Work

The piece we ran by Sean McConnell on an alternative approach to big bang engines kicked up quite a lot of debate about the merits of big bang engines vs screamer firing orders. As luck would have it, this week's episode of Bob Hayes' utterly outstanding MotoGPOD podcast featured an excellent discussion on the history and theory of big bang engines by Scott Jones. The segment was so well-written that we asked Scott if we could run it here, as a counterpoint to Sean's article. Scott, whose outstanding photos of the 2007 Laguna Seca race we were privileged enough to show last year, graciously allowed us permission.

We think this is one of the best explanations of how, and more importantly, why big bang engines work we have seen. We hope you agree.

Why Big Bang Engines Work

By Scott Jones

One way to look at MotoGP is as a continuing struggle to balance ever-increasing horsepower with a contact patch about the size of a compact disk. While common sense says that tire technology and suspension tuning have the most influence over where the limit of traction lies, for the last two and a half decades an element of internal engine architecture has had a profound effect on rear wheel traction and overall rideability.

MotoGP fans hear the big bang engine mentioned frequently, but what is it, and why does it improve a rider's control? The first question is easily explained. The second is not.

The idea behind the big bang engine is to move the pistons closer together around the crankshaft and make them fire in quick succession, rather than every 180 degrees as in an engine with a rational firing order. And instead of firing each cylinder individually, you fire two cylinders at a time, creating two large bangs per firing cycle instead of four smaller ones. The concept has its roots in flat track racing, where Harley big-bang V-twins dominated for decades. The premiere class saw big bang engines in Suzuki test bikes in the early 1970s. Cagiva tried their Bombardone engine in the mid 1980s, but it was Honda that made the big bang design an integral part of road racing with their 1992 NSR500. With this bike, Mick Doohan handily won the first four races of the season and would likely have run away with the championship had he not crashed so badly in practice at Assen and missed the next four races.

When Honda unveiled their big banger in 1992, the sound was dramatically different from the rest of the bikes on the grid. Other manufacturers brought audio analyzing equipment to the track to figure out what Honda was doing differently. The audio trick worked and soon afterward, the other teams were playing catch up, both on and off the track, putting their own big bangers into development to compete with the NSR500.

In the modern era, however, one can no longer tell for sure just by an engine's sound if it's a big banger or a rational firing order screamer. The many technological advances MotoGP has seen since the early 1990s have removed the distinct audible difference of this engine design. Engineers now choose inline or V layouts; single or multiple crankshafts; spring, mechanical or gas-powered valves; and so on, and each manufacturer must decide if a big bang layout works better with their other design choices than a rational firing order. The 2007 season saw bikes on both sides of this fence. One company even switched sides in the middle of the season! This is the protean nature of MotoGP: the bikes are always changing as teams search for whatever combination of technology will produce even a slight advantage.

But as development of the big banger continued in the 1990s, engineers had to determine what degree of separation was optimal for the overall engine architecture. For example, the first responses to the 1992 NSR500 were said to be a Cagiva that fired its pistons 66 degrees apart and a Suzuki that found 15 degrees to be the magic number. The only constant was that big bang engines, combined with the technologies of the day, made for lower lap times even as some very clever people wondered why this design made such a big difference to a bike's rideability.

Given nature's bias against things that are out of balance, the big bang engine is a crazy idea that should create more problems than it could possibly solve. You may remember the right hand rule from basic physics. Imagine an engine's crankshaft spinning in its case and turn your right hand in the same direction the crankshaft is turning. If you extend your right thumb, you have just identified a vector, or gyro effect, that the spinning crankshaft is generating.

The faster a crankshaft is spinning, the stronger that vector is and the harder it is for the rider to turn the bike away from that vector. Dual crankshaft engines produce a better handling motorcycle by reducing the engine's internal gyro effects. But adding a heavy, throbbing big bang to the firing cycle complicates this situation with its lopsided pulse. Such imbalance, especially in machines with as many moving parts as a motorcycle engine, usually leads to unwanted vibrations, which lead to inefficient function, which leads to loss of power, which leads to decreased performance and slower speed. Then add to the equation that the increased torque from the double piston firing and the close proximity of the timing requires a heavier, stronger crankshaft, bearings and gears. You have a heavy, less efficient, imbalanced engine making fewer horsepower than the engine with the rational firing order. But this big banger just happens to have the advantage of increased rideability.

And sometimes a given advantage is significant enough to outweigh its disadvantages. Loss of power is one thing, but as we know, MotoGP bikes have more power than they can efficiently use. With power to spare, some vibration in the right place just might be a good thing.

It is, according to a 1992 article by Kevin Cameron, who explained the big bang engine's benefit as an effective compensation for the increasing grip found when radial tires replaced bias-ply tires. Remember those amazing high side crashes we used to see so often with the 500s? The frequency of high sides reached a peak with the introduction of radial tires because the radials would grip like crazy until a certain point, then suddenly break loose, only to grip again just as suddenly a split-second later. This process happened faster than a rider's perception could detect it, which meant that one moment he was riding at the limit and the next he was flying over the handlebars. With bias-ply tires, the transition from full grip to full sliding was gradual, and the rider could feel the limit of traction approaching as the rear end of the bike started to hang out more and more. With the new radial tires, however, by the time he found the limit of traction it was too late.

But how can the firing scheme of the engine give the rider better feedback about rear tire grip? There are at least two theories about this.

One theory suggests that while human perception is much too coarse to tell one millisecond from another, a MotoGP tire endures its very stressful and very short life being profoundly affected by many forces, one distinct millisecond to the next. Not only is gravity forcing the tire against the road surface, but as the bike is leaning from side to side the tire is fighting severe lateral pressure. The bike is also braking frequently and, most importantly for this discussion, accelerating with tremendous power.

Under acceleration, the aforementioned milliseconds 'feel' different to the tire because it senses each rotation of the crankshaft not as one steady force but as an ever-changing pressure. As a cylinder fires, for a very brief moment that force pushing the tire forward is at its most intense. But quickly that force decreases as the piston slows down a bit on its way to the bottom of its stroke. Once there, it reverses direction and heads back up on the exhaust stroke. If no other pistons were involved, it would continue to slow down on the intake and compression strokes until the next ignition forced it to accelerate again. When you fire pistons individually and every 180 degrees of crankshaft rotation, the rear tire feels a cumulative affect of these brief forces of acceleration as a relatively regular and steady pressure - good for times when conditions are ideal, but bad when, say, the power of the engine combines with other factors to cause a loss of rear tire grip. The tire suddenly breaks free of its grip and spins until grip returns, which it always does, and often so suddenly that the rider experiences a high side.

Instead of the rational firing order's more even pressure under acceleration, a force that makes the tire grip grip grip until it suddenly breaks loose, the big banger delivers huge, torque-filled pulses due to two cylinders firing right before the other two cylinders. The engine's entire power cycle is compressed into a brief double pulse that at high revs momentarily overcomes the tire's grip and causes a very brief slip. After the double bang, the tire recovers its grip as the pistons decelerate and progress toward the next combustion strokes. This first theory says that the series of ultra-brief slips creates a unique situation when exiting turns. As revs climb, lateral forces on the tire cause these micro slips to become sideways movement of the bike's rear end. The rider can use this gradual increase in lateral slippage to sense the limit, just like he could with a bias-ply tire's gradually increasing slippage. Thus the big bang engine makes a radial tire mimic the best quality of a bias-ply tire, its gradual slipping as it approaches the final limit of traction.

This was the theory back in 1992 when Cameron explained the big bang engine's benefits in Cycleworld. It was also thought that compressing the timing of all combustion strokes gave the tire rubber time to rest up between big bangs and thus maintain top performance longer into the race. But as recently as November, 2007, Michael Scott wrote: "The tire people have yet to understand why a syncopated drumbeat of firing intervals should be easier on their rubber than the steady, even pulse of an inline four, but it is clearly so." After many years of considering why the big bang engine delivers its undeniable benefits, some very clever people are still wondering exactly why it works.

Which brings us to a more current theory, that of Yamaha's chief engineer, Masao Furusawa. At the end of the 2007 season, Furusawa gave a presentation in which he explained his theory of the big banger's benefits in terms of the engine's internal harmonics. Instead of reintroducing gradual lateral slipping to help the rider sense the limit of grip, the quick dual pulses of the big bang engine create a much different harmonic state during acceleration.

Just as the tire in the previous theory can sense subtle differences in the forces of the accelerating and decelerating piston, the crankshaft in Furusawa's theory creates a noticeably different harmonic signature when the pistons are fired in close succession.

Again we are dealing with milliseconds and distinct changes in the movement of various engine parts during those very brief periods. Friction causes the piston to decelerate after combustion, and so does the necessity of reversing direction when the piston approaches top dead center and bottom dead center. Again, think back to beginning physics and how something moving in a given direction at a given velocity wants to keep doing just that. After ignition, the piston is moving very quickly down the bore until it reaches the limit imposed by the connecting rod. Rather suddenly it is forced to stop, and then head in the opposite direction. As it is moving down the bore, it has considerable inertia and kinetic energy, both of which have to be accounted for as part of the reverse of direction. Both forces are absorbed by the crankshaft, something Furusawa called 'inertia torque' to differentiate these forces from combustion torque, the force created by the ignition of the fuel mixture.

Just as wind resistance increases exponentially as speed climbs, so inertial torque increases as the revs climb. So while inertia torque is a factor in your road bike, you don't operate its engine at sufficient revs to notice a problem. But MotoGP engines run fast enough that inertia torque becomes a very noticeable problem indeed.

To explain just how this problem manifests itself on the track, Furusawa used the metaphor of tuning a radio. As you turn the dial searching for the desired station, you hear the noise of signal interference decrease as you approach a spot where the signal strength is at its peak. The noise is still there, but the interference is low enough that you hear a clear signal. In Furusawa's metaphor, the rider is using the throttle to tune in a good signal to the rear tire. If there is too much noise between the throttle and the tire, the rider doesn't sense a strong signal and has little notion of where the limit of traction lies. If the interference is low enough, the rider has a good connection to the tire via the throttle and can get closer to the limit of traction.

Inertia torque is noisy, and thus interferes with the rider's ability to tune in a good signal. Enter the big banger, which reduces the periods of inertia torque by compressing the firing pattern. As the crankshaft is absorbing inertia and kinetic energy from the pistons and connecting rods, it's doing so in a smaller window of its revolution. The result is a longer period of each revolution that is noise free, or relatively so, giving the rider a stronger signal between the throttle and the rear tire.

In spite of their troubled 2007 performance, Yamaha had done much testing of different big bang engine schemes, and according to Furusawa, all results backed up his inertia torque theory. Is the big banger question answered once and for all? Maybe, and maybe not. Scientific history is full of explanations that were accepted one day, only to be refuted with more complete data the next. That two such experienced and clever individuals as Kevin Cameron and Masao Furusawa have had such different ideas about why the big bang design works suggests that we may never know, in any definitive way, the big banger's secret. Given, the two theories presented here are decades apart, and the older theory is based more on speculation than on testing data. But Michael Scott's recent remark about the tire people still not knowing why the big banger is easier on their tires makes plain that there are still big bang mysteries to be solved. We may never know everything, because the dominant package in MotoGP last year was a screamer, not a big banger.

In spite of the big banger's successes since 1992, it has not always been the design of choice in the premier class. As a prototype series, MotoGP finds its engineers constantly re-evaluating older technologies as new ones arrive on the scene. The big bang engine is no exception, and it has come and gone according to influences such as continued tire development and rule changes. The switch from two-stroke to four-stroke engines was a major reset for designers, and the early 990cc engines were for the most part screamers as engineers sought maximum horsepower to complete with the holdover 500cc two-strokers in 2002. But when Ducati announced it would enter the premiere class, it went back to the big bang engine right away. In February 2002, Ducati Corse Director Claudio Domenicali explained the decision like this:
"...further analysis led us to decide that the best solution was a 'double twin' and therefore we designed an engine with four round pistons which, thanks to a simultaneous two-by-two firing order, reproduces the working cycle of a twin. This will generate the 'big bang' effect, making the rear tire work in a way that extends its duration and improves rider feeling when exiting curves."
While that first MotoGP Ducati showed promise, it wasn't until Ducati replaced their big bang engine with a screamer in the 800cc GP7 that they won the world championship.

Ever since 1992, engineers have faced the dilemma: more horsepower at the expense of rideability with a screamer engine, or less power with an advantage when exiting corners with a big banger? Again, each new technology must be taken into account in the search for the current season's best solution. When pneumatic valve systems entered the scene and offered higher revs and more power, once again teams had to re-evaluate the screamer-big banger question. As tires improve, teams must decide if this year's rubber is good enough to allow the abandonment of big bang engines. The big bang pendulum swings back and forth. Sometimes teams reveal their choices, and sometimes they don't. Ducati announced that the GP7 would be a screamer when the bike was revealed at the beginning of the season. Kawasaki announced that their 2005 engine would be a big banger as part of that bike's introduction. Yamaha switched to a big banger in 2004 but didn't publicly confirm this choice until the 2007 season ended. In a recent interview on GPone.com, Randy Mamola said that Honda switched from a big banger to a screamer during the 2007 season. This was likely due to the lack of power relative to the Ducati at the beginning of the year. Honda continued to push the last spring-valved engine in MotoGP to its probable limit of performance, and by the end of the year had the engine Ducati feared most.

So what will we see in 2008? Honda's testing of their new pneumatic-valved engine has not been the success they were hoping for, and it looks like Hayden and Pedrosa will begin the season on last year's spring-valved screamer until HRC can get the required power from the newer technology.

From Furusawa's presentation, it seems clear that Yamaha will stay with a big banger for its harmonic superiority, though in the aforementioned GPone.com interview, Mamola speculated that Yamaha will certainly offer Rossi a screamer at some point if their current package continues to lag behind more powerful engines.

Ducati will almost certainly stay with an updated version of its GP7 screamer. Suzuki seems content with their big banger, but 12 weeks after the Valencia test, teams went to Sepang, where Kawasaki, a big bang proponent since 2005, made news by testing a screamer engine. A team spokesman would not admit that the team is moving away from the big bang engine for competition, saying that this was a test of 'other technologies.'

Other technologies are always a complication. Honda proved that the big banger was the right way to go in 1992. The dramatic change in tires when radials replaced bias-ply tires made the big bang engine a success, regardless of exactly why the different firing scheme worked. But other technologies happen, and something as significant as a fundamental change in tire construction has arrived that may very well make the big banger a thing of the past: electronic control of power delivery. Ducati's electronics package is said to combine GPS data (to tell the computer exactly where the bike is on the track) with live lean angle information so the computer knows just what the bike is doing and can control the engine's output accordingly. Computer-controlled engine mapping is now done not only on a gear-by-gear basis, but also on a corner by corner basis. As electronics get more and more sophisticated, the rider gets more and more help controlling the power, which is just what the big bang engine is supposed to do at the expense of added weight and lower horsepower.

So Kawasaki was using a screamer to test other technologies, rather than considering a switch from big banger to screamer for competition? Does a team need to admit that it would like more horsepower if their electronics allowed their riders to get that extra power to the ground? It seems that a screamer test is more likely a test of the team's electronics, to see if the current computer package is capable of taming the added power the rational firing order produces. Or, in Furusawa's terms, is the new software sophisticated enough to overcome the signal noise generated by inertia torque and give the rider a good throttle-to-rear tire connection?

So the big banger's future is far from certain. Advancing electronic control of power delivery could spell its demise. Or, something like the recent spec tire and spec ECU threats could become reality, forcing teams to abandon the allure of the screamer's greater power and return to big bang engines. The only thing that is certain is that MotoGP will continue to change as engineers search for even a slight advantage of technology. For the foreseeable future, at least, the big bang engine will certainly be one of the many factors they will consider.

Scott Jones is a photographer and writer. You can see more of his photographs over at http://www.turn2photography.com/, or read his blog over at http://blog.scottjones.net/. You can contact him via his website.

More Regulatory Madness - This Time, It's Rev Limits

It seems that Ducati's first world championship title has upset the major Japanese manufacturers a very great deal. After Honda got the FIM and MSMA to reduce the capacity to 800cc, they fully expected to be able to dominate the MotoGP class as they had after the previous change, the switch to four-stroke engines in 2002. They had not reckoned on a tiny Italian factory stealing their thunder by gambling on maximum horsepower, and humiliating the big players, and natural heirs to the MotoGP crown.

So it seems like the big players - or more specifically, Honda and Yamaha - have hit upon a quick way to neutralize the threat posed by Borgo Panigale: Autosport is reporting that Honda and Yamaha are pushing for rev limits to be introduced in MotoGP. Under the scheme, engines would have an artificial ceiling set on the maximum number of revs per minute they could spin at. More interestingly, the figure quoted is a maximum of 19,000 rpm. The fact that the Ducati is the only bike to rev above that number cannot be a coincidence: all of the other manufacturers' powerplants stop revving at around 19,000.

For both Honda and Yamaha, any such rule would be a godsend, as Honda is struggling to get its pneumatic valve engine working, and is having to make do with the limits imposed on engine speeds by using conventional steel springs, generally thought to be around the 17-18 thousand rpm mark. The other proponent is Yamaha, who have struggled in the horsepower stakes ever since the inception of the four stroke era in MotoGP, and have had to rely on outstanding handling and the riding genius of Valentino Rossi to remain competitive. With limits on engine speeds, Yamaha would at least be chasing a target which has stopped moving quite so quickly.

Understandably, Ducati oppose the move. They feel, with some justification, that they are being penalized for using the natural advantages of the desmodromic system they have become synonymous with, despite only switching to the system some 50-odd years after its first use. Honda's RC212V project leader, Shinichi Kokubu, cited costs as a reason for imposing rev limits, but Ducati's engineering genius, and the brains behind the GP8 project, Filippo Preziosi dismissed this argument out of hand. "I say since we are able to get this performance with a system that is fitted on a road bike like the Monster 695, the issue of costs doesn't hold water," he told the Gazzetto dello Sport.

Ducati are not alone in their opposition: Kawasaki are also against the limits. As the factory with the smallest budget in MotoGP, any such regulations would hit Kawasaki the hardest.

The proposed rule changes are unlikely to be accepted, as they would most likely require a unanimous vote of the MSMA, which comprises the motorcycle manufacturers involved in racing. But the proposal is an ominous sign. When Dorna CEO Carmelo Ezpeleta threatened to impose a single tire on MotoGP at the end of last year, he unwittingly opened a Pandora's box, with manufacturers now seemingly willing to use rule changes as political bargaining chips for exerting pressure. But MotoGP's problems should surely not be settled in the political arena, but out on the track. In a prototype series, rev limits surely have no place.

Guest Column - The Big Bang vs. Screamer Debate in MotoGP

With the MotoGP teams switching back and forth between "big bang" and "screamer" firing orders, there is a lot of discussion about the relative advantages and disadvantages of the two engine configurations. On the one hand, Ducati has elected to switch back to the screamer configuration, with a great deal of success, while Kawasaki is working hard on its own version of the screamer, their task made more complicated by the fact that the Green Machine is an inline four. In the other camp, Yamaha are utterly convinced of the merits of the big bang engine, and have declared that they will not use a screamer again.

And there are those who believe there are even more options that this. An Australian physicist and motorcycle racer called Sean McConnell sent us a piece exploring some of the rationale behind the big bang, and offering a suggestion on how to get the benefits of both firing orders. We hope you enjoy it.

The Big Bang vs. Screamer Debate in MotoGP
by Sean McConnell

I haven't really had too much to say of late of my racing activity, except that I'm selling my bike and plan to buy something bigger, but this issue of screamer style engine vs. big bang in MotoGP is something that has piqued my interest of late, see this article on Crash.net for a bit of a background, that site contains many such articles on the topic that can be found with a simple search. Here's my two cents on the issue.

For the uninitiated a screamer style engine is one that:

"Has an equal amount of time between the firing order of each cylinder during the rotation of the crankshaft"

For a four cylinder engine, a screamer configuration would see one cylinder firing every 180 degrees of rotation on the crank.

A big bang styled engine is one that:

"has a very short interval of time between the firing order of each cylinder, and an extended break until each cylinder fires again."

It takes 720 degrees of crankshaft rotation for a four stroke engine to complete the well known cycle of intake, compression, ignition and exhaust. In a four cylinder, MotoGP big bang engine, all the cylinders fire within a very small angular range of each other, my guess would be within 90 degrees.

The guiding philosophy being that in a big bang engine, the "relaxation time" is long enough between the time when the engine is applying force to the road (the first 90 or so degrees of crankshaft rotation, or ignition) and the time when it's going through the non-force applying functions of a four stroke engine (exhaust intake and compression), that the remaining 630 degrees allow the tyre to re-grip, such that if too much force is applied during that 90 degrees of ignition and the tyre begins to slide, there is still 630 degrees of non force application. This provides a buffer for the rider to not be sent over the handlebars.

Changing up through the gears means that force is applied to the wheel with decreasing angular frequency. For example, if there is a one to one relationship (we'll call this first gear) between the application of force to the wheel and the engine, then in the big bang style engine cited above, force will be applied to the wheel through the angles 0 to 45 degrees, then no force between 45 to 180 degrees, then force from 180 to 225 degrees then no force from 225 to 360 degrees, thus completing one full rotation of the wheel. As the gearing increases, the angular frequency decreases, if there is a 2 to one relationship (we'll call this 2nd gear) then force is applied between 0 and 22.5 degrees, no force from 22.5 to 90 degrees and so on.

So we have seen how the angular frequency decreases with gearing, shortening the time the tyre has to re-grip the road if too much force is applied during ignition. As wheel speed increases, the time it takes to complete one full rotation naturally decreases. So there are two things that shorten the time a wheel has to re-grip the road if too much force is applied during ignition, wheel speed and gearing. The higher the speed and the higher the gear, the less "buffer" a rider has during a slide.

Until now we have only focussed on a big bang engine, for a screamer engine, the situation is certainly far worse. A big bang engine can provide far more "buffer" as speed and gear increases than can a screamer. The screamer engine effectively is applying force constantly to the wheel, there is never any (useable) relaxation time. When Honda switched the NSR500 to a screamer in 1997, riders we're throwing themselves off all the time, only the skill of the rider could compensate for such a nasty peice of machinery, one of the reasons Mick Doohan won an incredible 12 of 15 races that year.

But there is a way for a screamer to compete with the big bang in this battle to squeeze in some sort of relaxation time for the tyre, should there be a sudden loss of grip. The solution comes from, as indeed the entire development of motorcycles, the bicycle. In time trials, it is not uncommon for cyclists to employ an elliptical front sprocket (a bicycle mechanic would call it a chainring). The reason being that an elliptical sprocket can smooth out the application of force to the tyre by changing the torque profile during the rotation of the crankshaft. On a bicycle, the main application of force is to push down on the pedal, the rest of the rotation of the crankshaft, you are simply waiting until your leg is in position to re-apply that downward force. The elliptical front sprocket drastically shortens this waiting time between the application of force. The torque profile changes as your leg reaches the bottom of the stroke, the gearing decreases at the bottom of the stroke, pedaling becomes easier, and your leg moves quicker through this period of non-force application, significantly extending the time that force is applied to the tyre.

For a MotoGP machine, the philosophy is the same, but applied in reverse. Where an elliptical sprocket is used to smooth out the force application on a bicycle, it can be used to roughen it up on a motorcycle. What I'm suggesting is that an elliptical rear sprocket would change the torque profile as the wheel rotates, this is exactly what a big bang engine does, except now a screamer can play the same game. At zero degrees of wheel rotation, with an elliptical gear, whose semi major axis is vertical, the engine would "see" a large sprocket, and consequently the wheel would be easier to turn. At 90 degrees of wheel rotation, the semi minor axis would be vertical and the engine would "see" a small sprocket and the wheel would be harder to turn. What this means is that when the semi minor axis is at the vertical, this is the point at which it is most difficult for the engine to continue to over-apply force, and cause the wheel to continue sliding, allowing the rider a buffer that he doesn't get with a circular sprocket.

The added advantage of an elliptical gear is that it also eliminates the problem talked about earlier of decreasing the time between the application of force with increasing gear. Because it is the final drive sprocket, the application of force is greatest at 0 and 180 degrees (semi major axis at the vertical) and least at 90 and 270 degrees (semi minor axis at vertical) no matter what gear the bike is in. So in this case, the only thing acting to shorten the time between the application of force is naturally the increasing wheel speed, as described above.

Finally, there is the other argument for using the big bang engine, and it's an argument I can totally agree with. You can read about it in an article by Julian Ryder over on Superbikeplanet.com. It is the idea that a big bang configuration is able to somehow improve the quality of the "signal" that a rider receives from the rear tyre, so that they can better understand what the rear tyre is saying to them. Furusawa talks about a connection between throttle and tyre in terms of harmonics, and for me the explanation is simple. The philosophy is that with a big bang, and as I speculate an elliptical sprocket, you can apply some sort of input, such as the application of throttle to a tyre, and be given in return a useable amount of time to determine what that input has done to affect the motorcycle. It's like a feedback system, but with a screamer engine, the input is constant and permanent, there is no time to "hear" anything other than the input signal, you never get the chance to "hear" the feedback signal.

One potential problem for an elliptical rear sprocket is that it would cause the chain to flop around a bit more than usual, although I'm sure a simple mechanism could be devised to take the slack out of the chain, similar to a bicycle derailleur. In saying that however, the eccentricity of the sprocket would not need to be terribly much to achieve the desired effect, and a "derailleur" of sorts mightn't be necessary, and besides that, if you've ever been to a race and watched a chain driven motorcycle, you'd know how much the chain flops about anyway. It is not clear to me why none of the teams that have ever used a screamer style engine did not or have not tried this, as from an engineering perspective, it is the simplest solution to the problem. And according to Occam's razor, the simplest solution is usually the best.

Sean McConnell lives in Australia, and writes his own blog ranging over a broad spectrum of subjects called Join the RevoluSEAN!. You can also read the article printed above over on his blog.

Ten Kate: MotoGP An Option For 2009

As the World Superbike opener in Qatar approaches, the media is focusing its attention on some of the more unusual aspects of the World Superbike paddock. One of those anomalies is the HANNSpree Ten Kate Honda team, which is fielding not 2 but 3 top names in the Superbike championship: former MotoGP veteran Carlos Checa, double British Superbike champion Ryuichi Kiyonari, and reigning World Supersport title holder Kenan Sofuoglu. An unusual step, as every other team consists of either 2 riders, or a senior team of 2 experienced veterans, and a junior team comprising 2 up and coming talents.

This unusual team line up has had the Dutch motorcycling press asking questions. In an online interview (in Dutch) with team boss Ronald ten Kate, the magazine MOTO73 asked whether the three-man team was part of a plan for a MotoGP entry in 2009. Ten Kate's response was interesting: Instead of flat out denying it, as you would expect, the Ten Kate team boss was flustered, telling the interviewer, Marjo Muntjewerf, "You've caught me off guard, there..." He then went on to say that running three top riders was part of a plan to build up a team structure "to allow us to possibly do something alongside our current efforts in the future. You don't run a third rider without a reason, a third rider is part of realizing our future plans. Those plans could be to introduce a proper Junior team in World Superbikes ... On the other hand, we could use that same structure as a basis for an entry into MotoGP."

Whatever the current status of their plans, running a third rider in World Superbikes means that by the end of the season, Ten Kate Honda will have three fully-trained teams of mechanics, and enough personnel to mount a serious MotoGP effort. With Lucio Cecchinello, team boss of Team LCR speaking publicly about his plans to achieve even better results in 2009, before the 2008 season has even started, it looks like the race for 2009 satellite Hondas is in full swing already. With so many titles in World Superbike and World Supersport under their belts, Ten Kate surely have a very strong hand indeed when it comes to getting support for a MotoGP entry in 2009.

Ducati And Dorna Quash Schumacher Rumors

The rumors that Michael Schumacher was preparing to race in MotoGP as a wildcard, which we reported here earlier, are turning out to be just that, rumors. According to Autosport.com, both Carmelo Ezpeleta, the CEO of Dorna, and Ducati team boss Livio Suppo rejected the suggestion out of hand. Suppo denied ever having spoken to the German Formula 1 champion about the matter, and Ezpeleta dismissed the rumor with a joke: "Maybe we'll have him racing with Kimi Raikkonen in a sidecar!"

Any prospect of Schumacher turning his hand to professional motorcycle racing is looking increasingly improbable. MotoGP is very much a young man's game, and with Schumacher due to turn 39 this year, he has his age against him.

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