Formula One car development blog

Pirelli escapes trouble with standing waves in tyres

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It was just 2 years ago when Pirelli attracted some negative publicity with tyre cuts at the same Spa-Francorchamps when on Friday and Saturday, images revealed considerable standing waves in the rear tyres of some cars. It's a known phenomenon, but the intensity of it at Spa even left some top engineers without explanations.

Perhaps the most obvious occurrence was the one on Lewis Hamilton's Mercedes F1 W08. As he exited the chicane and powered up onto the start finish straight, the car vibrated intensely for around 5 seconds. The vibrations were thanks to an unusual deformation of both rear tyres, even though Hamilton wasn't particularly hard on the kerbs. A bit later on in qualifying, the deformation broke off a rear wing element on Lance Stroll's Williams as well. The issue cost him a second run in Q1.

On Saturday evening, after Pirelli had asked teams to share data, so they could better analyse the issue, Williams' Paddy Lowe confirmed he didn't see such deformation before.

"We have often seen before a kind of standing wave in the sidewall, but in this case, we're seeing a standing wave on the tread with sort of a flat threepenny bit shape to it," he said. "I've never seen that before. It's a very high amount of energy in that."

Pirelli reported on Sunday morning the issue was of no real concern to them, with lab simulations showing no immediate issue with the tyres themselves. Mario Isola, Pirelli's motorsport chief, said they were still trying to understand the matter.

"It looks like we have this vibration just out of Turn 19 and Turn 1, so it is a specific point," he admitted, "it's not on all the circuit. But because it is the first time we see it so clearly, and maybe also the slow motion images were announcing a little bit this effect, when we see this, we want to understand it.

"We are checking with all the teams, because it's important to have feedback from them. They have not only the data, they look at the suspension, they look at the floor, they look at the wings, so they can give us more complete feedback. Obviously if you touch certain frequencies, then you can generate a failure."

Indeed, the rotational force exerted on the wheels, combined with high grip of the tyres creates flexing in the tyre walls. At a certain frequency - which depends partly on the tyre construction - flexural waves can form around the edge of the tyre. It appears that in this case at Spa, the energy in the waves was such that the tyre wall didn't normalise when completing a full rotation, resulting in the more than obvious shudder of the car itself.

It'll be interesting to see if Pirelli can discover and reveal a complete explanation, and if such behaviour will be seen again at Monza, where cars similarly accelerate hard out of slow corners.



Internals of Ferrari's 2014 water-to-air intercooler exposed

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Thanks to the bankrupty and public sale of some assets of the former Marussia F1 Team, we now get to take a very up-close look at some of the car's parts from 2014. Peter Bjorck for instance has bought a number of Ferrari engine parts, including the water-to-air intercooler and the unique butterfly wastegate from the Ferrari 059/3 engine as it ran during the 2014 season, the first year of the new hybrid turbo engines in F1.

In the below clip, Peter walks us through the intercooler, which sat in the engine's V. Air flew through it to cool it down before being guided towards the cylinder air intake plenums, one for each cylinder bank. Unpacking shows 16240 small water pipes in the aluminum intercooler.


F1 2017 explained: Power unit changes

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Following up on their videos on regulation changes, Mercedes have now highlighted the impact of these changes on the power unit.

In essence, it comes down to coping with the difficulty of having more full throttle each and every lap, while having to work against the increased drag that comes with the additional downforce. The increased stresses that will be put on the engine have resulted in a slightly heaver power unit for Mercedes, whereas the cooling requirement have also gone up so that the engine does not overheat while it is burning more fuel, and hence rejects more heat.

Mercedes' engine chief Andy Cowell also explains why a 10% increase in full throttle per lap resulting in only a 5% increase in allowed fuel for the race, resulting in the availability of 105kg of fuel for each and every race in the 2017 season. Cowell said "this will at least prevent the crazy fuel saving measures that we have seen during 2014".


Exhaust solutions, mickey mouse or snowman?

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In a strange twist of events, fans have actually managed to create a little extra area for freedom of design in Formula One cars. The repeated calls for increased engine noise have made the FIA to request an investigation into what could be done to enhance the noise output of the new V6 Hybrid engines. The result of Magnetti Marelli's investigation, during which the company's engineers repeatedly visited F1's engine supplier dynos was that an additional exhaust pipe could resolve a bit of the problems.

The new regulations stipulate that either one or two seperate waste gate exhaust pipes must be added on the car, with the rules making clear that all pipes must be in promity to each other to avoid another attempt for designers to exploit the gases to their aerodynamic benefit.

Mercedes' engine chief, Andy Cowell, explained this week at Barcelona that the wastegate pipe could work as a silencer on the main exhaust. In particular when the wastegate is closed, its pipe is actually a dead end, making it a dampening chamber on the main exhaust. By removing that dead end, and creating a seperate exhaust pipe for the wastegate, the sound "is more pure, with less distortion".

Mercedes have measured this change on their dyno, and noticed an increase of maximum sound, up from 124dB to 128dB - whereas the V8 engines using until 2013 produced aroun 130dB. He did however also say that those are lab measurements, and should be taken with a grain of salt: "In the dyno, you don't have air passing around the exhaust pipes, which is obviously happening when the car is on track. This can have a significant effect on the sound levels. It also depends on the circuit, the accoustics with the grandstands, so essentially it comes down to perception".

On their 2016 cars, all but one team have chosen have two wastegate pipes. Mercedes put its pipes close together underneath the main exhaust, Red Bull have them a bit further apart from each other, and Williams even more. This setup is already being referred to as the "inverted mickey mouse" set-up. The resemblence is striking when looking at the Red Bull RB12 layout. Renault meanwhile have opted for a single, bigger pipe above the main exhaust. This has been nicknamed the "snowman" layout, again, no comment needed there.

The fact that most teams have chosen to have 2 wastegate exhaust pipes is interesting, especially when you consider that the Mercedes engine only has a single wastegate valve, meaning that teams need to split up the wastegate outlet into two pipes. According to Paddy Lowe, this has all to do with packaging: "It really isn't a big deal what kind of layout you are using. We have chosen two smaller pipes because of packaging reasons".

He also confirmed there is no real aerodynamic gain from the position of the pipes, except of course the packaging advantages of one layout to another, as a more streamlined or compact bodywork can of course have their impact in the car's drag or downforce generation.

It should also be noted that, while the current variety is a nice possibility in the regulations, teams and the FIA are currently still investigating an alternative route to improve engine sound.


Honda repositions oil cooler on new engine spec

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Honda have spent 3 of its 7 development tokens to resolve some of the most important issues of the carmakers' current F1 power plant, and subsequently made the upgraded engine specification available to McLaren for initial running on Friday at Spa-Francorchamps.

Part of the engine's upgrade include modifications on the combustion chamber, the intake and the exhaust system layout in an attempt to increase efficiency. The team have also reduced mechanical friction by changing the gear train system.

One visible change to the engine is the relocation of the oil cooler, as marked in the image. This cooler was previously and uniquely mounted high up in the engine cover, behind the airbox, and therefore somewhat apart from the engine itself. As the picture shows, this radiator has been moved to above the gearbox, slightly angled upwards to the back. The new location has reduced the length of the connections while enabling aerodynamicists to reduce the volume of the roll hoop and move the central outlet funnel lower down to increase rear wing efficiency. There will of course also be the benefit of the lowered centre of gravity, improving the car's cornering characteristics.

Also note that Honda's upgrades are not all present on the engines introduced at Belgium, with some items to be added and changed at the next two races.

At Belgium only, Jenson Button amassed penalties to drop him 50 grid positions, while Fernando Alonso totalled 55. Both had two new internal combustion engines fitted on their cars, 2 turbo chargers, 2 MGU-H and 2 MGU-K units. The Spaniard in addition took another penalty for the use of the 6th electrical control unit. The strategical solution enabled the McLaren drivers to take the penalties by dropping just 2 grid positions each, thanks to a rule change that made the penalties non-transferable to the next races.


Mercedes ditches log style exhaust on PU106B

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Following a year of running with a very compact log style exhaust (as pictured) in 2014, Mercedes have now chosen to ditch the concept and go for a more conventional equal lenght exhaust manifold as seen on the 2014 Renault engine.

An obviously different noise coming from the Mercedes powered cars yesterday was followed by a further confirmation from Mercedes' Head of Engines at Brixworth, Andy Cowell that the new Mercedes 2015 power unit, named PU106B, features an 'entirely new exhaust concept'.

Having strolled around in the pitlane at Jerez, I can confirm that at least Lotus is not running with a log style exhaust, but instead a wrapped package of exhaust tubes very similar in size and location to the configuration of the Renault powered cars in 2014. Sadly a picture is missing, but I'm sure visual confirmation will follow.

In 2014, Mercedes already started testing with an equal length exhaust manifold before switching to a log type at the final pre-season test in Bahrain. While that proved to be a good solution, not in the least for packaging reasons, an equal length manifold can provide advantages for the effectiveness of the turbo. As exhaust tuning is a rather complex subject and designing the optimal exhaust layout depends highly on the power requirements for a certain rpm range, it may be that the change is influenced by the reportedly higher revolutions that the new Mercedes is capable of.


What to learn from a temperature camera?

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Since the introduction of Formula One's new thermal camera images, there has been talk about the relevancy of the images, leaving apart the obvious coolness that is associated with it. It is for sure that such imaging will help people understand the complex nature of Formula One, and increase the technical interest in the sport.

Before going into what we've been seeing, one needs to take into account that the images are not meant to give away technical details that other teams could use. Instead, their calibration is not made public, making it unclear when an area is considered hot enough by the camera to be visualised as blue, purple, red, yellow or white. It is even possible that this calibration is not linear either, making it even less useful from a technical perspective. Nonetheless, the new images are worth a look, as they do certainly show a few things that were known before, but not actually visible.

At the Italian Grand Prix in Monza, FOM repeatedly showed images of the front wheels on Paul Di Resta's car. There it was clear that the sidewalls are considerably cooler than the thread, while the car's negative camber setting - a common feature in racecar setup - made sure the inside of the front tyres take the main load when the car is running in a straight line. When cornering, it is obvious how this camber setting works, as the roll of the car offsets this camber on the the outer front tyre - the one that takes the biggest load - making its thread heat up evenly across the entire width.

Now at the Singapore Grand Prix, Felipe Massa's Ferrari featured a rearward looking camera, showing how the rear tyres heat up and cool down during the course of a lap. That image showed that the rear tyres are heating up mostly during acceleration, and to a little less extent under braking. This is of course easily explained by the weight transfer of the car, as under braking, the weight shifts forward, hence also why the brake balance is set up so that more brake pressure is applied to the front wheels.

In addition, it's also clear that there is less or no camber on the rear wheels, as they have to work at their best on a straight line as well. Any minor camber angle however is easily offset by the downforce on the rear wheels, pushing the entire thread onto the tarmac under acceleration.

One final, and perhaps the most interesting observation we can make, is how the inner wall of the rear tyre is heating up. It is clear that this is mostly due to the Coanda exhausts that direct the hot stream of exhaust gases down onto the car's floor, passing alongside the tyre. This considerably heats up the rear tyres and has been a particular problem for some teams to keep under control. Mercedes AMG for instance reverted to their traditional exhaust during 2012 after finding out that their tried Coanda exhaust layout worsened rear tyre wear.

In the below clip, you will also clearly see how the tyre wall is hotter when the car is accelerating hard - due to the high RPM of the engine and hence the more powerful exhaust stream. Also look at the behaviour under braking, where downshifts are followed by a short increase in rear tyre wall temperature, again due to the increase of engine revolutions. All this of course is influenced by engine mappings, but as most teams now have a good understanding of the tyres, it's unlikely anyone is using less afterburn than possible to preserve the tyres.


Note that the only time the sidewalls of the front tyres were seen coloured, and thus relatively warm, was when cars left the pits, hence with the tyres still warmed up by the blankets.


Lotus tries extended wheelbase, no racing yet

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Lotus have been talking up their extended wheelbase E21 for a while now, but after strength testing was not completed in time ahead of the Belgian GP, its debut came at Monza. The team brought two sets of parts and opted to give Raikkonen only a chance to try it out in the Friday sessions.

The Finn though believed there was little or no performance gain in it, underlined by the fact that he and Grosjean - who still ran the shorter version - set identical best laptimes during FP2.

While usual wheelbase extensions are done by adding a spacer in between the gearbox and the engine, Lotus opted for a simpler solution by modified only the front suspension. While the pick up points remained the same, the frontal suspension arms are now angled less backward, moving the wheel forward relative to the chassis. Depending on the source, this increases the wheelbase between 7 to 10cm.

Because this also moves the front wheel axle forward, the nose also needed to be elongated, as the front wing had to be moved forward as well to comply with the regulations. Interestingly, the longer nose also saw the camera pickup points move forward, move further than the extension of the nose itself.

The change was thought of to change the weight transfer characteristics of the car, but should also enable a small aerodynamic gain as the front wheels are now further ahead of the sidepods.

Even though Lotus is convinced of its advantages, the suspension was replaced again on the #7 car on Friday night, reverting Raikkonen to the regular version. Team principal Eric Boullier however confirmed that it will definitely be seen again in future races.


Heat protective floor coating to shield against exhaust flow

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Red Bull Racing have likely kicked off a new trend in Formula One, as the team appeared with obvious coating on the car's floor, downstream of the exhausts. With the RB9 having one of the most effective designs to pull the exhaust gases down to the car's floor to seal the diffuser, its carbon fibre floor is also very much exposed to the heat of the burning hot exhaust gases flowing over the floor. Such single sided heat exposure is a risk for the carbon fibre laminate which may end up slightly bent, creating an unwanted effect on the car's aerodynamics. The severity of this very much depends on the exact thermal conductivity of the carbon fibres and the temperature resistance of the resin between the sheets.

Although the team have obviously not revealed which coating exactly is being used, one of the most popular suppliers of protective coatings in Formula One is Zircotec. Apart from coatings to protect against heat, the company has coatings that provide protection against wear; coatings that offer electrical insulation; and coatings (non-metallic) that offer electrical conduction, e.g. for earthing and for shielding sensitive instruments against stray interference signals.

In Red Bull's case it is quite obvious that its coating is targeted at protecting the carbon fibre floor against heat, seeing the area where it is applied. It is clear to see where, as the typical carbon fibre structure is hidden by the uniform colour of the coating.

Coatings like Zircotec's Performance range (known to be used in F1) are obvious candidates for this. They can be applied to a range of thicknesses from very thin (say 0.05mm thick) up to say 0.5mm thickness depending upon the required level of protection. Teams are also often requesting the coatings to be coloured to help disguise where they are used and which ones exactly are used.

Similar coatings can be found on various carbon composite components to protect them from fire/heat damage. These include brake components; various engine and exhaust heat shields; and engine parts. Additionally, as there are coating for metal parts as well, such as those currently used on exhausts, it could well be that the use of these coatings will expand even further due to the high number of new hot components that will be introduced around the engine as of 2014.


Red Bull use McLaren alternator on RB9

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After rumours emerged in the Italian press about RBR's alternator, Renault Sport have now confirmed to F1Technical that Red Bull Racing is indeed using a McLaren Electronic System alternator in combination with the Renault engine. The firm notes this is the case "for some time now", with all other Renault powered teams still using the Magnetti Marelli alternators, similar to last year.

Renault's technical director, Rob White, says this is the result of the problems during 2012: "We suffered unacceptable recurrent reliability issues with alternators fitted to the RS27-2012 engine that we supply to all our teams. At Renault, we take full responsibility for the design and integration of the engine and ancillary equipment supplied to our teams, including the alternator. We worked with the support of our teams and suppliers to develop countermeasures to eradicate last year’s problems. The work was underway before the end of the 2012 season. It was completed during the winter and validation was signed off in pre-season testing. These solutions have been implemented on alternators for all of our teams and we continue to monitor the situation closely."

While having two different alternator options now fitted on the RS27-2013, Renault also pointed out that the options to pick are still in Renault's hands, and that two alternatives are now available due to differing electrical requirements on different cars.

"The alternator generates electrical power to match the electrical consumption of the car and to maintain the charge of the battery. For chassis reasons, the electrical power requirement may vary between different types of car. In parallel to addressing the reliability issues experienced in 2012, and having consulted all our teams, we have increased the electrical power capacity of our alternators. To manage the technical and logistic risks, we have worked with two suppliers for the electro-magnetic components to provide alternator parts to our specifications. Responsibility for alternator supply to the teams and supplier choice for all components and assembly operations remains with Renault."

The options appeared to have paid off, as no issue was found on any car so far this year.