Tech obtain: Tips of the commerce in IndyCar gasoline saving
After discussing why groups will resort to gasoline saving within the final column, the pure follow-up query is, how do groups go about doing this? Whereas there are lots of strategic causes that groups will flip to gasoline saving throughout a race, in each situation groups will attempt to save gasoline in essentially the most environment friendly approach attainable. That’s, minimizing the lap time penalty as greatest they will whereas nonetheless hitting the gasoline goal.
How groups go about minimizing their lap time loss when needing to avoid wasting gasoline is determined by a number of elements: the aptitude of the engine producer to run completely different engine modes, the power of the motive force to adapt their driving method, in addition to the traits of the observe and the present visitors state of affairs. Engine producers, groups, and drivers will work collectively and spend big quantities of sources to optimize this facet of efficiency, be it on the dyno, in simulation, or throughout observe testing. The flexibility to avoid wasting gasoline with out shedding a lot time could be a big differentiator all through a race.
There are two major strategies for saving gasoline: the motive force can both change engine modes, or incorporate lifting and coasting. Every has their very own benefits and downsides, however they successfully obtain the identical factor: finishing the lap whereas saving gasoline in comparison with operating at 100%. Deciding essentially the most environment friendly approach to make use of one or each of those strategies over a whole lap nonetheless, could be very troublesome. Oftentimes, there are an infinite variety of methods to hit the identical gasoline goal, so groups will set about utilizing the engineering instruments at their disposal to search out the very best method.
Altering engine modes is comparatively easy. The engine producer can load numerous settings into the automotive’s ECU, which may then be chosen by the motive force by adjusting a dial on the steering wheel in the course of the race. Doing so will successfully (and with out giving an excessive amount of away) cut back engine energy and gasoline consumption in lockstep.
With regards to gasoline saving, that is the place the battle between producers lies. Providing lowered gasoline consumption for a similar energy in comparison with the competitors not solely offers groups extra race tempo when hitting the identical gasoline goal, but in addition opens up the variety of technique choices obtainable to them.
Since gasoline targets can change all through the race, groups will all the time guarantee there are a number of choices obtainable on the dial, every with its personal compromise of energy discount and lowered gasoline consumption. Groups can even use information from observe periods to advise over the radio as to what engine mode ought to be used for a given gasoline goal. With engine modes, the motive force can proceed to push with their driving model whereas nonetheless saving gasoline. Sometimes, when resorting to altering engine modes, acceleration is the largest compromise to efficiency (although there’s additionally an impact on prime velocity) resulting from having much less energy obtainable. On the plus facet, drivers can proceed to assault brake zones and nook entries they usually usually would.
Raise and coast
The commonest gasoline saving method for a driver is ‘carry and coast.’ As the motive force is nearing the tip of a straight and approaching a brake zone, they’ll carry nicely earlier than the traditional braking level, coast with none enter on throttle or brake for far, after which apply the brake when sufficiently near nook entry.
Alexander Rossi confirmed simply how efficient the carry and coast method may be at Indy in 2016. F. Peirce Williams/Motorsport Photographs
The concept is that gasoline consumption is intently tied to being on-throttle, so if a driver wants to scale back consumption, they must carry for some period of time in the course of the lap. Lifting in the direction of the tip of a straight is right as a result of that is when the motive force is closest to prime velocity, so they’ll coast farther, and due to this fact save extra gasoline. Moreover, a automotive is accelerating a lot much less on the finish of the straight than it’s at the start (since acceleration begins to taper off the nearer the automotive will get to prime velocity), so lifting on the finish of the straight can be much less penalizing on lap time. Subsequently, the upper the entry velocity right into a nook, the higher it usually is to make use of carry and coast to avoid wasting gasoline.
The primary profit to carry and coast is that there is no such thing as a de-tuning of the engine: acceleration for many of the straight stays the identical as it could when not saving gasoline. Nonetheless, the detriment to carry and coast is sort of clear: on a regular basis loss is concentrated at nook entries.
Evaluating gasoline save strategies
To get an preliminary comparability between approaches, engineers will flip to a significant device referred to as lap time simulation. This can be a software program that can use a numerically modeled automotive, observe, and driver to resolve physics equations as a approach of making information for a digital lap as if it actually occurred on observe, however with the good thing about each single parameter being managed by the engineer.
Lap time simulation is a vastly advanced topic in its personal proper; one that may do all the things from investigating potential setups to predicting the impact of fixing ambient situations. It is among the most necessary items of software program an engineer will use. For the scope of this text although, it permits the engineer to match gasoline saving approaches to see whether or not altering engine mode or carry and coast is the quickest technique to hit a gasoline goal.
Beginning with essentially the most fundamental of examples, a simulation of accelerating from the apex of 1 nook, down a straight, to the apex of the following nook is modeled. Working at 100% burns 0.301 gallons, however say the gasoline goal is 0.286 gallons (5% financial savings). The engine producer – who has been performing some work on the dyno – says that they’ve three engine modes to strive. The primary is full energy and full consumption (Mode 1), the following presents 4% energy discount for a 5% financial savings in gasoline consumption (Mode 2), and the ultimate choice presents 8% energy discount for 9% gasoline financial savings (Mode 3). Lap time simulation may be run iteratively as a way to clear up for the required carry and coast distance till the gasoline goal is achieved. Mode 1 goes to require 135 ft of carry and coast to hit the gasoline goal, Mode 2 will nonetheless want 50 ft of carry and coast, and Mode 3 may be run with none driving changes wanted to be made. With these simulations, overlays of velocity, gasoline consumption, and lap time (plotted versus distance) may be in comparison with a push lap with no gasoline saving, and the outcomes can then be analyzed.
Transfer your cursor over the graphs to disclose extra particulars
On this instance, all three gasoline saving approaches use the identical quantity of gasoline, however utilizing Mode 1 and 135 ft of carry and coast is 0.23s sooner than going straight to Mode 3. That may be a large period of time for only one nook! Additionally of word, utilizing Mode 1 and 135 ft of carry and coast is barely 0.02s than pushing flat-out, which is hardly any loss time in any respect for utilizing 5% much less gasoline. When executed effectively, the lap time loss from gasoline saving can near nothing.