rFactor 2

rFactor 2

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Early Development Preview (WIP) Brabham BT44B 1975
 
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May 6, 2016 @ 5:32am
Oct 11, 2016 @ 7:56am
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Early Development Preview (WIP) Brabham BT44B 1975

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Description
Steam Development Preview

Have you ever been curious to try an rFactor 2 car in its early development stages?

Here's your chance to do it! We are proud to announce a brand new series of content that will be released here exclusively, through the Steam workshop - it's called the “Development Preview (WIP).”
You will get to witness “the making of” the Brabham BT44B (1975), watch its graphics and physics take shape, and participate with your feedback.

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Further Details

The car is in early development preview stage, which means that in no area do we consider the car complete, although certain areas may be near completion, anything is subject to change.
This first installment is very early in the visual department, however, we obtained the physics from a high quality 3rd party source.

The original physics are essentially an rFactor 1 compatible format, and so this car and the corresponding blog http://isiforums.net/f/entry.php/5-Hello-and-welcome-to-our-new-physics-development-blog can be thought of as an example of converting, and then optimizing physics parameters to suit the rFactor 2 engine.
If you follow this car, you will see progression from various updates available in the rF2 engine, but it also shows that an rFactor 1 vehicle physics, can work rather well in rFactor 2. A lot has been done to maintain backward compatibility of files from the older engine.

The first installment is utilizing only the original rFactor 1 engine compatible physics parameters, with the exception of the mandatory TGM tyre model. The current tyres are not yet optimized and are a mildly tweaked copy of the most similar tyres currently created and available to us so far in rFactor 2. It does not incorporate the new CPM model advances. This will obviously change as we progress and build a dedicated tyre set for this car.
Since rFactor, there have also been some minor physics corrections to the core of rFactor 2, which also improve the accuracy.

Brabham BT44B
By 1975, it was standard practice to marry a Cosworth DFV engine to a Hewland FG gearbox and to base your car around this proven combination. The BT44B was no exception, and rightly so, as the car achieved Brabhams most successful season since 1969. The Brabham BT44B was an advanced machine, managing 2nd place in the constructors title of 1975, by significantly improving upon reliability of the BT44 while improving performance in key areas. The car was designed by the legendary Gordon Murray and presented a sleek, simple package that also emphasised a low centre of gravity, as evidenced by the triangular shape of the 'sidepod' area.

Driving technique.
The then recent trend was to put smaller tyres on the front, and ever larger tyres on the rear of the car, the former done primarily for aerodynamic purposes, while the latter was merited by the need to maximise drive from the powerful 470hp Cosworth DFV. To generate the needed heat in the rear tyres (and simultaneously not overload front tyres) the weight had been shifting rearwards to match. The resulting driving style is a somewhat nervous, but controllable car which needs to be driven hard, and owing to bias-ply tyre constructions, in a loose manner where you constantly drive in a shallow slide.
To get the most from the vehicle, brake late, trailing into the corner as necessary, turn in progressively but sharply, then balance the car with the throttle and steering. The car is mostly driven from the back end, use the powerful engine to keep the car pointed in the right direction. To exit you will want to apply ever more throttle to ensure the maximum grip is being used, and sliding the rear end will not harm your speed, though it remains possible to overdrive. The car is quite neutral in balance, and the setup quite open, allowing the driver to change the cars characteristics to suit their driving style.

Braking.
Aerodynamic downforce was still a relatively new, but already well established concept in racing. The car produces about 800kg of it at top speed. Though not quite increasing grip in a linear sense, this means that with the car weighing only 650kg with driver (795kg on a full tank), the braking potential is nearly double at vmax, compared to when static. This requires a firmer foot on the brake pedal on initial application, and easing off before entering the corner. Lockups are easy, and another new concept of ventilated brake discs allow for excellent stopping distances and brakes quite resilient to fade, while not impervious to overheating. Owing to the low radius of the front tyres, their inertia is quite low, making lockups quite sudden. It will take practice to perfect, but braking is quite rewarding in this car. Another important factor is that you will need to blip the throttle upon down-shifting to avoid locking rears, even if their massive stature sedates this effect to a certain extent.

Accelerating and Shifting.
Despite the low weight of the vehicle, and the power of the Cosworth, giving some 470hp @ 10500RPM, the grip given by the approximately 411mm wide rear tyres (tread width) mostly allows aggressive throttle applications. In certain conditions, such as very low speed driving and wet weather driving, it will still be quite easy to overcome the grip and slide or spin the rear end excessively. Rough throttle inputs usually do not yield to the best lap times, and easing into it delivers the best results. When taking higher speed corners, the aerodynamics significantly improves grip and it should not require caressing the throttle too much.
The engine was known to be somewhat fragile in revs exceeding point where peak power is delivered, thus the engine is limited to approximately 10,600RPM, with short shifting hurting performance quite significantly. Thus we can say that short shifting is only recommended to do so if conserving fuel or limiting wheelspin under slippery conditions.

Tyre Management.
Not only were tyres becoming wider, but also softer. Despite this, it was still clearly possible to do a complete race on one set of tyres, but some caution was needed to ensure the tyres degradation was kept to levels allowing the driver to be competitive through an entire race. Even with ever improving pitstop times it would not yet be worth the time required to change tyres.
The Brabham BT44B was also a little bit harder on its tyres than competitors, while the tyres can be damaged, it was possible to push near flat out for an entire race without too many issues. You should be looking to keep the car in a shallow slide and keep excessive sliding to a minimum, as needed when fighting for position. The optimum operating temperature is approximately 70-100°C. The peak slip angle is around 7-11° and should not be exceeded often, even though the grip fall-off is low.
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30 Comments
Christopher_E  [author] Jan 17 @ 1:48am 
The project is still ongoing :)
Mak80_ Jan 15 @ 12:19pm 
no development news?!?
is project stopped?
3 months without any updates?
soul_talk Jan 14 @ 1:44pm 
Very good job, but it seems to me that is excessive longitudinal grip, it is hard to go to spin even in first gear
Alex72 Dec 24, 2016 @ 6:05pm 
Super cool thank you! :)
Dirty_Harry Nov 25, 2016 @ 12:59pm 
No download link yet punks !
texaco83ita Nov 21, 2016 @ 12:57pm 
Good job guys
gorka.santisteban Oct 11, 2016 @ 2:51pm 
Superb car Christopher. It was a success in the first race of our BT44 league in Interlagos.
One thing I think this car needs: A delay when driving auto-clutch. In the testes I've done, the car changes gears faster in auto-clutch and paddles than using left foot cutch pedal and H shifter. A delay should be able to compensate this.
Thanks for your great and hard work
Harris Muhammad Oct 11, 2016 @ 9:01am 
Thank you Christopher, for making this.... great mod !
Christopher_E  [author] Oct 11, 2016 @ 8:11am 
Latest Version is up v088 - Changelog added
Proff_Chaos Sep 6, 2016 @ 12:21am 
This is a great mod. Thanks for this, and I look forward to the finished work.