Race and Vehicle Simulations

“Fernando we’re not sure the fuel dash is working correctly. Can we have multi H13 position two?”

“Try purple C3 position three Jenson, exit diff locking.”

These words are typical of those we hear on pit-to-car broadcasts in Formula One (F1) racing in the modern era. Words of drivers who are making constant adjustments to their machines in order optimise the car’s performance, tyres, fuel, and now Energy Recovery Systems (ERS.).

In 2014, F1 introduced new rules to dictate that all cars must operate on Hybrid power units; a change that completely re-worked the way F1 cars were to function in a race situation, and would completely change the packaging requirements of the vehicle as laid down by the designers.

In 2015, McLaren commenced their relationship with Honda as a works engine partner with their new MP4-30 chassis that was mated to the Honda RA615H V6 internal combustion engine (ICU). This intricately engineered 1.6 litre lump did not come alone, however, as the hybrid rules dictate that an F1 car must run two ERS systems with an MGU-K (Motor Generator Unit-Kinetic) and an MGU-H (Motor Generator Unit-Heat) which recharge energy into a battery that can be deployed to the rear wheels adding an extra 160 horsepower (hp) to the 600-odd that the ICU is pushing out.

Some time ago, our good friends at iRacing announced that they would be modelling the McLaren-Honda MP4-30 within their venerable simulator.  This meant that us every day simracers would be given the chance to get to grips with the various controls and switches that Jenson Button and Fernando Alonso have spent the season with; a tantalising prospect at the time, but questions were there about exactly how much control we would have over the cars various systems.

We needn’t have worried:- iRacing’s history had given us a clue. Despite being considerably less complex as a racing machine, iRacing’s implementation of the 2009 Williams-Toyota FW31 covered all the bases admirably, with in car controls for various differential controls, variable brake bias and a few other “trick” bits of kit on the car. At RAVSIM we’re great believers in a car simulation being just that, if there is a switch in the real car, it should be in the sim, and you should be able to use it. Be it entry differential settings on an F1 car, or heater controls in a BMW E30, if the car has it, so should the sim. It’s not something most developers agree with, however.  Some sims don’t even trust us with controlling our own pit-lane speed limiter button, after all. Thankfully, iRacing’s view is a little more aligned to ours.

Last week the MP4-30 was released, and since then the bold and the brave of iRacing’s top drivers have been working day and night to understand the various settings and controls on the machine. With various in-car settings that can (and in some cases have to) be managed during a race, along with a few other settings and configurations that can only be worked with in the garage, it has been a minefield for some of the less technically minded simracers. As someone who has been fascinated with these controls since the car was released, I am going to try and see if I can decode some of the “magic” going on.

“Jenson default X5B.”
“You’re going to explain that one to me, I can’t find it.”

So to start with, let me skip back a little bit and try to explain what each of the components in the MP4-30’s power unit actually do.

First is the petrol engine, or ICU. I’d presume that if you’re a simracer and you’ve found your way to this site then you probably know what one of these is. In this case the Honda RA615H is a 1.6 litre V6 unit with the V set at 90 degrees, as dictated by the rules. The ICU is connected to a turbocharger allowing the engine to be more compact but produce similar power to the 2.4 litre V8 engines used in F1 prior to 2014. The turbocharger is a device used to efficiently utilise the energy stored with the engine’s exhaust gases, comprising of a turbine and compressor supported by bearings on the same axis.

Exhaust gas energy rotates the turbine powering the compressor, which in turn compresses and increases air fed into the engine’s combustion chamber, thus allowing for more fuel combustion and a higher power output.

In 2013, F1 engines were limited to 18,000 rpm, but from 2014, the rev limit was reduced to 15,000 rpm, along with a maximum regulated fuel flow of 100Kg/hour capped at 10,500 rpm. Thus, as power output increases proportionately with the amount of fuel burned, higher revs burn more fuel, and increase output, in a shorter time. By capping the maximum fuel flow at 10,500 rpm, the same amount of fuel flow is available with revs above this point, increasing mechanical resistance, and decreasing the merits of revving higher than 10,500 rpm. F1 engines of the past were designed to maintain higher revs to create higher output, but the new hybrid F1 shifts the focus to designing engines that use energy more efficiently.
In the cockpit this means that the driver has to be careful to shift up to the next gear at the right time in the rev range, rather than “run it to the limiter.” This efficiency is enforced yet further with a fuel limit in races of 100Kg, which often sees drivers having to use different engine modes for managing fuel consumption.

Within iRacing these settings can be adjusted in car by moving the “G” control between 0 and 9 (available on the in-car controls menu and visible on the gold thumb dial on the left of the steering wheel). The lowest setting, 0, gives 100% turbo boost pressure, with each increment upwards limiting the boost by 1%. Thus a setting of 9 gives 91% boost from the turbo. The higher settings provide better overall fuel consumption at the expense of ultimate power from the ICU component.

Whilst Honda’s ICU has come under some scrutiny for its performance in 2015, it’s fair to say that this is far from the weak link in the solution.  Honda’s experience in Japan’s Super GT with the hybrid CRZ GT300 machine, as well as their involvement in WTCC which operates with a similar “small-block allied to turbocharger” design, suggests that their engineering group have quite some experience in this area. Nevertheless, the RA615H was a completely new design, which facilitated McLaren introducing a new gearbox for 2015 to optimise the mating of the ICU and gearbox in the rear of the car.

“Jenson this is fuel three, we need fuel six.”
“You would not believe how early I am lifting off.”

Next up comes the MGU-K. This unit is not dissimilar to the KERS systems that F1 has been running since 2009. This takes electrical energy harvested from the rear axle under braking, which is stored in the ERS battery, and deploys it to the rear wheels when under power. When powering the car using electrical energy stored in the battery, the MGU-K adds 160 hp (at maximum deployment) to the ICU’s 600 horses.

This is not unlike the systems used in road cars such as Honda’s “Fit”. Within the F1 rulebook, however, the electrical energy charging the battery from the MGU-K is limited to 2 MegaJoules (MJ) per lap, and the maximum energy used by the battery to power the MGU-K is limited to 4 MJ per lap, presenting a compromise in management of this energy over a lap. With the design restrictions ensuring that energy is harvested at a lower rate than it can be deployed, there is even more compromise to be built into the equation.

Back in the iRacing cockpit we have a number of controls for the MGU-K that can be manipulated by the driver on the fly, as well as a few that can only be set in the pit lane. Let’s take a look:

MGU-K Regen gain (TRQ – Gold dial to the right of the steering wheel): With settings from 0-9. This manages how aggressively the MGU-K harvests energy from braking events. With 9 being the most aggressive setting and thus harvesting the most energy into the battery at a given time.

MGU-K deploy mode: Set to either Fixed or Adaptive, this determines how the MGU-K deploys power to the rear wheels with settings managed via separate switches. Fixed mode applies a fixed deployment rate at all times, whereas Adaptive will automatically adjust the MGU-K deployment rate to work to a set ERS battery charge state.

MGU-K deploy fixed (MFC – dial on the bottom left of the steering wheel): This defines a fixed rate of MGU-K power output to the rear wheels under power that is adjustable between a range of 1 to 14. With 1 being maximum output at all times (which will heavily decrease battery) and 14 being no deployment (leaving the ICU to do all the work). This setting only applies if the MGU-K deploy mode is set to fixed with the above switch.

MGU-K deploy adapt (MFH – dial on the bottom right of the steering wheel): In adaptive mode the dial is also adjustable between 1 and 14. This manages the MGU-K deployment rate based on a target ERS battery charge state. Thus setting the dial to 1 will set the deployment rate to a more aggressive (more power) rate with a minimum ERS charge set at 20%, with 14 managing the available battery to a maximum charge rate of 85%. Conceptually thus, on a setting of 1, once the battery gets towards 20% the adaptive system will reduce MGU-K deployment to allow the battery to recharge, and then automatically increase deployment again when more battery is available.

MGU-K deploy ramp (F – only available in the garage): This sets how aggressively the ERS power is deployed to the rear wheels upon throttle. Adjustable between 0 and 9, with 9 smoothing out the power delivery for improved traction and 0 offering a heavily aggressive deployment

The MGU-H is the next piece of the ERS system puzzle, which adds to the overall efficiency of the power unit. The MGU-H converts heat energy from exhaust gases into electrical energy to recharge the ERS battery. ERS-H is yet to be used in road going hybrid cars and consequently is a major area of research that may eventually benefit the greater motoring world.

Unlike the MGU-K, the F1 rulebook does not place any energy usage restrictions on the MGU-H. Electricity generated by the MGU-H may be fed directly into the MGU-K, effectively bypassing the MGU-K regeneration restrictions and tapping the full 160hp.  This highlights the importance of developing a system to fully utilize the MGU-H, and any new F1 power unit heavily depends on how effectively the MGU-H performs. Within iRacing there are no controls for the MGU-H as it operates based simply on the exhaust gases escaping from the manifold. What can be seen within the iRacing MP4-30 is that, when one sets the MGU-K regen setting to zero, there is still charge being pushed into the ERS battery, coming from the MGU-H. Alas, the charge harvested from the MGU-H is usually negligible, as the MGU-H will be sending energy to the MGU-K on throttle, so the overall power delivery needs to be balanced alongside MGU-K deploy and regen settings.

So how does it all hang together on the track? At all times, as long as the driver sets the switches accordingly, energy is harvested into the ERS battery, or is deployed from the ERS battery in different ways depending on what the car is doing.

Under braking the MGU-K generates electricity from part of the kinetic energy lost when the car is braking, and stores that electricity in the ERS battery. As the MGU-K’s maximum output is 160hp (or 120 kiloWatts) and the amount of energy allowed to be stored in the battery is 2MJ per lap, the MP4-30 needs to brake for around 16.7 seconds per lap to reach this maximum charge.

Upon acceleration out of corners the car can accelerate faster by adding the power output of the MGU-K to the ICU’s power output, in the process depleting the charge in the ERS battery. However, concurrently the MGU-H is utilising the exhaust gases to recharge the ERS battery while the turbocharger uses its compressor to send compressed air into the engine. Under full-acceleration, the exhaust energy fed to the turbine can increase to a point where it exceeds the amount of air the compressor can handle to feed into the engine, in this situation the MGU-H converts this excess exhaust energy into electricity, which it then sends directly to the MGU-K for deployment to the rear wheels.

There are no rules on how much electricity the MGU-H is allowed to generate, so the MGU-K’s output can be added to the ICU’s output without worrying about the rules on the amount of electricity that the battery can charge or discharge. Thus, unused exhaust energy can be efficiently used to accelerate faster.

The MGU-H also solves the problem of turbo “lag” on power application by using an electrical motor to power the turbo’s compressor, saving the turbine from having to wait for the exhaust gas to do so.

“Can you have a look at the braking for the hairpin please. How many more laps on the red button?”
“Jenson we have 11 laps red button remaining.”

Phew! So anyone coming fresh to modern F1 technology may need a break after reading all that. But it’s not quite over. There are a few more tricks up the F1 driver’s sleeve in the cockpit of the MP4-30. Like the FW31 before it, this car is fitted with various settings for management of the active differential at the rear of the car, as well as dynamic brake bias settings. I am not going to go into depth on these settings, but looking at the newer options available with this car we note that buttons can be mapped to functions such as the “Push-to-pass” and DRS.

Push-to-pass, or the overtake button (OT on the steering wheel), is simply a button that allows the MGU-K deploy mode to switch to its most aggressive deployment rate (1) for the duration that the button is held down. Whilst this obviously brings about a noted depletion in the ERS battery charge, it can be extremely useful to pull off an overtaking move.

DRS (Drag Reduction System) opens a slot gap in the rear wing on certain denoted parts of the circuit that significantly reduces drag and increases top speed. This is freely usable in practice and qualifying sessions, but restricted in the race to being used only when within one second of the car in front. Opening of the DRS has to be engaged by the driver, with one green light on the top left of the steering wheel becoming illuminated when entering the DRS detection zone (the area on the track in which you must be within one second of the car in front), which increases to two green lights when the car enters the DRS zone, at which point the driver should press the DRS button as soon as possible to maximise performance through the DRS zone. When the DRS is engaged, there will be four green lights on the dashboard. Opening the DRS in the rear wing has a knock-on effect of reducing rear downforce and thus upsetting the front to rear downforce balance. This is something the driver must be aware of when the DRS is open.

Managing the various in car systems when driving the car at speed is a juggling act that any aspiring McLaren-Honda MP4-30 driver in iRacing will have to master if they are to achieve success. Each circuit will differ in configuration as battery re-charge is dependent on braking events and total deployment will vary based on the amount of time on throttle. The key to this setup is to find an optimum balance between deploy and regen on the MGU-K that you can work within, whilst using the push-to-pass button to increase power at required intervals.

Naturally, you want to maximise performance with the lowest possible deployment setting, if MGU-K deployment is set to fixed. If you perform a lap with a deploy rate of 1, and a regen rate of 0 then you may find on some circuits that the ERS battery is flat before the end of the lap, with the maximum deployment of 2MJ completed well before the end of the lap. Thus you need to start to dial in some regen. The assumption would be that maximum regen would be desirable, to always recover as much battery in braking events, but the compromise here comes in braking performance. As the MGU-K works to harvest energy from the rear axle, there is a an additional diff locking effect that not only increases braking zones, but also introduces understeer into the corner entry phase. It is distinctly apparent in tests that with the lowest possible regen settings on the MGU-K, the shortest braking distances can be achieved. As well as that, the feeling in the car on entry is “cleaner”, whereby the driver feels more in control of the car’s balance upon entry to the corner via their own foot pedals. As the driver adjusts the MGU-K regen and deploy settings the balance of the car on entry and exit can change notably, meaning a driver has to become adaptable to these changes on the fly. A qualifying run with heavily aggressive MGU settings will suit for one lap, but when given the balancing act that may be required to maintain efficiency over a full race it is not unlikely to see a laptime difference of up to 4 or 5 seconds between the two sessions.

To find the optimum laptime in the MP4-30 a driver must work to find a balance between MGU-K deployment and regeneration that suits the particular track layout and their driving style. All the while maintaining sufficient ERS battery charge when you need it for overtaking, keeping fuel consumption under control (day-to-day iRacing races are typically 50% of F1 race distances with a fixed fuel load), hitting the DRS button in the right places, managing brake bias and differential settings as fuel load changes, and, you know, not crashing a car capable of hitting speeds well in excess of 200mph very quickly.

“Ok Jenson so manage the temperatures. We want you to save as much fuel as possible and we need some hard braking events to keep the temperature in the front brakes.”

“And rub your tummy and pat your head? Alright we can do this.”

Many column inches have been written this year about McLaren-Honda’s relative lack of performance compared to the rest of the F1 field. This is not noticeable in iRacing, of course, because there are no Mercedes, Ferraris or William’s out there on the track. As such the MP4-30 seems really rather fast.  One area the iRacer will not have to worry about as much as McLaren’s incumbent world champion drivers is heat management. At the beginning of the 2015 season there were notable concerns in Woking about the reliability of the MP4-30 with regards to its various ERS components. With the McLaren chassis being designed around the “size zero” design concept: Whereby to optimise airflow over the car for aerodynamic performance the internal packaging of components was made increasingly tight. Since 2014, with two MGU’s, a V6 ICU, turbocharger, compressor and turbine to shovel into the space behind the bulkhead and in front of the 8 speed gearbox and rear suspension assembly this design concept has pushed F1 engineers to the limit.

With the turbine reaching up to 1000 degrees Celsius, you have torsion bar dampers, anti-roll bars and hydraulic system components, servo valves, wiring harnesses and the like only a few millimetres behind the turbine which all need to be kept relatively cool and protected from the heat being generated. Meanwhile the aero guys are asking for less bodywork and thus less space internally.

From what is documented, this caused considerable reliability headaches for McLaren-Honda in the earlier part of the season, and drivers were routinely having to manage temperatures where possible by staying out of the dirty air of other cars, and careful brake temperature management.

iRacing, as yet, still does not allow us to manage radiators or cooling ducts within car setup, and while brake and engine temperature are modelled in the sim, there is no real management of it from the driver’s point of view required. As well as this, only one of Pirelli’s tyre compounds has been modelled, the yellow-walled soft tyre, which on first impressions is quite easy to manage on wear (At Road America and Nurburgring GP testing sessions).

With that aside, iRacing’s McLaren-Honda MP4-30 is a masterpiece of systems modelling in a commercial sim, and by putting control into the hands of the player and refusing to dumb it down the team in Bedford, MA can only be commended.

Driving the MP4-30 is a joy, driving it quickly is a huge challenge that truly allows us to appreciate the work that goes into each and every F1 race for the men in the cockpit.

With thanks to Fernando Alonso and Jenson Button for their illuminating quotes taken from the 2015 season.