McLaren MP4-30

The car was nicknamed the "size zero Formula One car" by the team for its distinct sharply tapered rear end, which was achieved by designing the Honda engine to operate at higher temperatures than other engines. At the end of the season, the car recorded a best finish of fifth place at the Hungarian Grand Prix, and had scored just twenty-seven points, leaving McLaren ninth in the World Constructors' Championship. Button and Alonso were classified in sixteenth and seventeenth positions respectively, in the World Drivers' Championship, while Magnussen was not formally classified. McLaren’s ninth-place finish in the 2015 Constructors’ Championship was their worst performance since 1980 (wikipedia-search).

Design team Having developed the McLaren MP4-29 in 2014, Tim Goss and Neil Oatley returned to design and build the MP4-30. Peter Prodromou, who previously worked for McLaren between 1991 and 2006, was recruited back to the team from Red Bull Racing—where he had served as the team's Head of Aerodynamics—to aid in designing the MP4-30 and to oversee the team's trackside operations alongside former Sauber designer Matt Morris. The RA615H engine was developed at Honda's Automobile Research and Development facilities in Utsunomiya in Tochigi Prefecture—the same facility used to develop the Honda Civic WTCC for use in the World Touring Car Championship and the Honda NSX-GT to compete in the Japanese Super GT championship—with the project led by Yasuhisa Arai and also McLaren earned direct factory works support from Honda.

Early development

Honda had previously competed in Formula One as a constructor when they purchased British American Racing in 2006, before selling the team to Brawn GP ahead of the 2009 season. With the sport introducing a brand-new engine formula in 2014 and Mercedes, their engine-supplier, establishing their own team, McLaren sought a new engine supplier with a view to a long-term relationship. The partnership with Honda was first announced in May 2013, and the RA615H engine spent the next eighteen months in development. The team used Mercedes' PU106A Hybrid engine in the McLaren MP4-29 throughout the 2014 season. Development of the McLaren MP4-30 started with the McLaren MP4-29H/1X1, a variation of the MP4-29 that was developed to test the new engine. The car made appearances at test sessions at the Silverstone and Yas Marina Circuits, where it was driven by McLaren's testing and development driver Stoffel Vandoorne. The testing programme of the MP4-29H/1X1 was limited by technical problems with the engine that prevented significant running and the chassis was shelved following its appearance at Yas Marina, with the team carrying the engine over to the MP4-30 chassis ahead of the first pre-season test of the 2015 season at Jerez de la Frontera. The car was the first of the 2015 entries to pass its mandatory crash tests, getting final approval from the Fédération Internationale de l'Automobile (FIA) in December 2014.

Livery Ahead of the 2015 season, McLaren revealed the MP4-30 car with a black and silver chrome livery with red trim on 29 January 2015. The initial livery was criticized by fans because it included the silver element which was considered as Mercedes-Benz's de facto official corporate colour that caused disappointment for most McLaren fans. Later in the season, McLaren ditched the original black, silver and red trim livery and thus unveiled a revised livery featuring dominant black and red colours starting from the Spanish Grand Prix.

Pre-season testing The MP4-30 made its début at the first pre-season test at the Circuito de Jerez. The team endured a difficult start, with the RA615H engine suffering from a series of recurring mechanical faults that restricted the team's running over the four days, and they finished the test having completed the least amount of mileage among those present. The issues that had plagued the car were not resolved in time for the second test at the Circuit de Barcelona-Catalunya, prompting McLaren to replace some parts supplied by Honda with parts that they had developed independently in 2014. The team finally managed to get some substantial running in during the final test in Barcelona; after completing just seven laps on the first day, Jenson Button was able to complete over one hundred on the second. However, with two weeks until the opening race, the longest stint of continuous running that the MP4-30 had completed was twelve laps of the Barcelona circuit. This distance—55.8 km (34.7 mi)—is less than a quarter of a full Grand Prix distance of 307.1 km (190.8 mi).

Testing accident The team's pre-season preparations were overshadowed by an accident involving Fernando Alonso on the final day of testing that saw Alonso hospitalised with a concussion and ruled out of the third and final test. Kevin Magnussen, McLaren's test and reserve driver, was drafted in as his replacement for the remainder of the test and the opening round of the season. Alonso later attributed the accident to a steering failure, although McLaren maintained that there was no evidence of a car failure in the telemetry data following the accident.

Power unit — Honda RA615H

An analysis of the RA615H revealed that Honda had developed the power unit with the 2016 season in mind; although no substantial revisions to the Technical Regulations had been put forward, the decision was made so that Honda could make a head-start on developing its 2016 engine without wasting time trying to maintain development of a juvenile power unit in 2015. Furthermore, with McLaren developing the MP4-30 to have tight packaging, Honda introduced several radical concepts to the engine that allowed them to develop a smaller engine that weighed just 145 kg (320 lb) and would fit within the confines of the chassis, with the trade-off being that it required additional water cooling to keep temperatures under control. First, the turbocharger was split and positioned alongside the Motor Generator Unit-Heat (MGU-H)—the generator harvesting heat energy from the exhaust manifold used to power the turbine—and positioned within the cylinder banks forming the 'V' configuration of the engine. In order to make this fit, Honda eschewed the use of a centrifugal fan in its single-stage compressor in favour of using several smaller fans positioned at intervals along a shaft. Although this would limit the ability of the turbocharger to build up the maximum amount of boost pressure, the 100 kg/h (220 lb/h) fuel flow limit introduced in 2014 minimised the impact of this. The Motor Generator Unit-Kinetic (MGU-K)—the generator harvesting energy from the engine spinning while under braking—was positioned in front of the engine to deliver energy directly to the crankshaft, following the convention established with the introduction of the kinetic energy recovery system in 2009. The batteries housing the energy harvested by the MGU-H and MGU-K were merged with the Electronic Control Unit and positioned in front of the engine. Both the MGU-H and MGU-K were capable of harvesting 4 MJ (1.1 kWh) of energy per lap. However, under the 2015 regulations, both systems could only deploy 2 MJ (0.56 kWh) of energy per lap. At the Hungarian Grand Prix, it was noted that Honda had taken the unusual step of giving each engine an individual designation such as "PU18 'Greyhawk'" and "PU22 'Erica'".

In-season development

With each engine manufacturer on the 2015 grid being granted some limited scope to develop their engines, McLaren and Honda were given some leeway to develop the RA615H power unit before it was required to be homologated despite having had eighteen months of uninterrupted development prior to the first race. Under the 2015 regulations, the power units were divided into thirty-two areas for development, and Honda were given permission to develop nine over the course of the season. The first engine updates were introduced at the Canadian Grand Prix, aimed at improving the reliability of the motor generator units, but by mid-season, the engine was reported to be producing 120 bhp (89 kW) less power than the Mercedes PU106B Hybrid engine, the benchmark of the 2015 grid. During preparations for the British Grand Prix, Ron Dennis, the McLaren CEO and chairman, noted that the team was encouraged by the aerodynamic data they had collected on the chassis, particularly its mid-corner speeds which he claimed were similar to those produced by other teams. He further added that the car's performance issues could be traced back to a lack of outright power and poor fuel efficiency from the engine. Éric Boullier, the team principal, further suggested that the main problem that the team faced was improving the efficiency of the RA615H's energy recovery systems, both in harvesting and deploying the additional power, and that by developing these areas, the car could make up several seconds on lap time, enough for the car to compete regularly for podium finishes. After the engine struggled with reliability issues throughout the first half of the season, Yasuhisa Arai declared himself happy with Honda's progress following the British Grand Prix and announced that the development focus would switch to improving the performance of the RA615H ahead of the next round of planned updates at the Belgian Grand Prix, with plans for a wider range of updates spread out over the remainder of the season, with the Singapore Grand Prix earmarked as the first race that would be representative of the new engine's performance. Honda predicted that the updated RA615H would produce enough horsepower to rival the Ferrari 059/4 engine. Despite being an average 13.3 km/h (8.3 mph) slower than the fastest driver through the speed trap over the first half of the season, an analysis of the engine's performance revealed that it had gradually reduced the deficit to the Renault Energy-F1 2015. Yasuhisa Arai went on to suggest that the engine had a 25 bhp (18.6 kW) advantage over Renault, but was still an estimated 50 bhp (37.3 kW) behind Mercedes. The updates introduced in Belgium included changes to the combustion chamber, intake and exhaust aimed at reducing stress on other engine components to allow them to operate at peak efficiency. An analysis of the team's mechanical problems further suggested that there was a critical fault in the internal combustion chamber that was having a residual effect on the other components by placing undue stress on them, and an inefficient MGU-H that was using energy faster than it could be harvested with the net effect that the engine would lose up to 160 bhp (120 kW) halfway through a lap. During the race, the car was observed to be harvesting energy at the top of the Kemmel Straight—the fastest point on the circuit—while other cars were deploying their energy at the same place. Despite Arai's insistence that the RA615H had an advantage over the Renault engine, Fernando Alonso estimated that the car was losing up to three seconds per lap to Mercedes at the Italian Grand Prix and was unable to attack or defend its position against the Renault-powered Scuderia Toro Rosso cars, even with the drag reduction system deployed. Alonso's comments came amidst the first public signs of tension between McLaren and Honda with reports that the team had requested that Arai be removed from his position as Project Manager. An analysis of the development carried out by rival manufacturers revealed that both Mercedes and Ferrari had found an additional 40 bhp (29.8 kW) over the course of the season through the development of bespoke fuel blends and the reconfiguration of their combustion chambers to promote more efficient fuel burning, offsetting the gains made by Honda. Honda started to introduce their third and final round of upgrades ahead of the Russian Grand Prix, focusing on the internal combustion engine and associated exhaust parts with the aim of improving the efficiency of the MGU-H and gradually introducing new parts over the next three rounds. The engine ancillaries were reconfigured to allow for better packaging within the chassis, while the axial compressor was replaced with a more conventional—albeit smaller—design. The exhaust wastegate was also updated ahead of planned development for 2016, with the exhaust outlets reconfigured to improve the engine's power curve. Honda chose to focus on the internal combustion engine instead of directly addressing the problems with the MGU-H as they felt that the problems could not be adequately addressed with their remaining allowance for in-season development, and instead deferred development of the MGU-H until the end of the season when the restrictions on development would be lifted. The upgrades were given to Alonso, with Button scheduled to receive them two rounds later at the Mexican Grand Prix. The updates were received positively by Alonso, who pointed out that he had been setting lap times that were faster than those recorded by Lewis Hamilton during the opening phase of the race, and that the team had identified the potential to gain two and a half seconds per lap in 2016 through further refining of the engine and by adopting aerodynamic design elements used by other teams. Button was less optimistic, pointing out that the engine would struggle in Mexico as the high altitude of the Autódromo Hermanos Rodríguez—some 2,229 metres (7,313.0 ft) above sea level—would leave the turbine down on power given the low density of the air. Although the team's predictions of a difficult weekend were proven true after qualifying, they highlighted the deficit to the leading Mercedes through the less power-dependent sectors of the circuit as being consistently within three tenths of a second, the narrowest the margin had been over the course of the season.

Reception The RA615H was widely criticised by the wider Formula One community, with the team's struggles becoming a recurring theme throughout the 2015 season. This criticism was particularly directed at Honda's Project Manager Yasuhisa Arai and the rigidly compartmentalised structure between the two companies that saw Honda develop the engine independently of and with minimal input from McLaren, and their failure to recruit any engineers from rival engine manufacturers Mercedes, Ferrari and Renault, even after Arai's acknowledgement that Honda had underestimated the demands of the sport and the technology required to compete. Responding to the criticism, Arai claimed that the "size zero" approach demanded by McLaren—attempting to create a more compact design to fit the tight packaging of the MP4-30 chassis—had compromised the overall design of the engine and limited the ability to develop it over the course of the season. Fernando Alonso defended the move, suggesting that Honda's independent development programme would make it difficult for other manufacturers to copy the RA615H's design. McLaren CEO Ron Dennis took a broader view, attributing the team's difficult season to a range of factors—including chassis development and staff morale—rather than the engine performance alone. Further criticism was directed towards McLaren's decision to consciously limit Honda's involvement in the sport to supplying a single team, with Scuderia Toro Rosso and the embattled Manor Marussia touted as a potential Honda customer to gather additional data. However, the team rejected the criticism, arguing that the infrastructure needed to establish such a partnership would distract from their own campaign, and earmarking the 2017 season as the earliest possible date that an expansion could be considered. With the team revising its performance targets down from podiums to regular points, Éric Boullier acknowledged that the team would be facing a budgetary shortfall for the 2016 season, estimated to be some US$23 million (£15 million), as the team had originally anticipated finishing fifth rather than ninth in World Constructors' Championship, and with it, a great share of prize money. In the build-up to the Japanese Grand Prix, Alonso noted that although addressing the power unit's shortcomings remained the team's biggest challenge, he was unhappy with some of their trackside operations, citing a lack of running in Friday practice sessions, under-preparedness in starting procedures and pit stops, and unreliability of other parts—such as the gearbox—as compounding the problems with the engine. After being powerless to defend against repeated overtakes during the race, Alonso was overheard condemning the RA615H as "embarrassing" and a "GP2 engine" over the radio. Despite Honda alluding to running the engine at its peak performance at the Hungarian Grand Prix, the former driver and Sky Sports commentator Martin Brundle opined that he felt McLaren were pursuing a research and development programme rather than a pure racing programme, and so were looking for different outcomes for the season rather than outright results. With Button qualifying thirteenth for the Russian Grand Prix, half a second behind the Red Bull of Daniil Kvyat, Brundle described the team as having made "their first meaningful progress of the season". However, three races later and following the upgrade introduced in Mexico, Brundle said that the engine was still down on power, inefficient, and lacking reliability and therefore suffering the same issues that had plagued it since the start of the season. At the conclusion of the 2015 season, Yasuhisa Arai left his role within the team. He was replaced by Yusuke Hasegawa, the managing director of Honda Research and Development, as Honda focused on development of the RA615H's successor, the RA6