ORECA developed an all new Le Mans Prototype in on behalf of the Rebellion team in 2014. Team Boss Bart Hayden had looked around at a number of options for a car to run in 2014 including the Dome S103 but in the ended opted to have a bespoke car created. The car was initially by the Toyota RV8K engine as was the case with Rebellion’s previous Lola chassis. An LMP2 version was launched in 2015.
The first concept sketches of the car bore little resemblance to the final design, though some elements did remain.
“The design bureau began the prototype study from a blank page and completed the project in record time” David Floury ORECA Technical Director enthuses. “Barely 12 months from the first pen stroke to the shakedown. We relied on our previous experience in order to reach our objectives. Of course, the approach had to be pragmatic and efficient along the same lines as the FIA/ACO technical regulations. Despite this we had no limit in terms of design. For example, there was no obligation to have very low sidepods. It was the aerodynamic developments and simulator results that dictated this choice. Then there were a few details where we could take a few liberties, such as integrating the REBELLION logo above the headlamps. But it was always performance that guided our choices.”
The car completed its first laps in April 2014, a month behind schedule. After the initial study phase, the design of the new Le Mans Prototype continues according to plan with each stage of the project progressing smoothly. Initially three chassis were to be built, two of them will became the two 2014 Rebellion race cars, the third chassis was built as a reserve, but many more examples were eventually built.
SHAKEDOWN: PAUL RICARD HTTT 2014
The Rebellion R-ONE made its track debut near ORECA’s facility in the South of France, although it was missing some components. “There was a lot to take into account, above and beyond the aerodynamics. We had an objective in terms of usage : to have a true capacity to affect the car’s settings, accessibility to parts, as well as the life cycle of said parts. We also had to adapt to the new regulations and to energy management which have a heavy impact on the car’s functions. Therefore we looked to reduce drag, focus on weight balance, etc. Innovation implies much research and development. At the same time, our budget isn’t the same as the major manufacturers and our situation doesn’t allow for maximum risk taking. Everything must be weighed with innovation against risk taken. It’s a fine balance that must be found between risk and reward” Floury adds
“There wasn’t a desire to have an either wide or thin nose. The ORECA 01 had a thin nose, but that’s because we began with an existing design. With the R-One, we had more latitude. Honestly, we have solutions for noses that are more original and perform better, but these were not realistic for a private constructor and in the time frame we had. It’s a compromise you have to find and accept” Floury concluded.
RACE 01: SPA
The Rebellion R-ONE made its public debut just ahead of the Spa Six Hours race in Belgium. After the first race at Silverstone, where the team ran 2013 spec Lola-Toyotas, securing a fourth place overall, the team went directly to the Paul Ricard HTTT to start testing the R-One and build the cars ready to race at Spa-Francorchamps.
The on track form of the R-ONE was not clear from its first days running at Spa, as both cars struggled with new car issues, one having most of its running curtailed with an electronic issue that saw it unable to start the engine without selecting a gear.
The new car was designed and developed by ORECA, and as a result many of the design elements of the new R ONE are inspired by other cars built by ORECA, this can clearly be seen when looking at the sidepod shape and the concept of the trailing edge of the front fenders.
The overall shape is clearly heavily inspired by the Courage LC70 / ORECA 01 (above) with the trailing edge of the front fender following a similar concept also.
Whilst the ORECA 01’s racing in the WEC’s LMP2 with the SMP, KCMG teams do not feature a turning vane on the lading edge of the side pod it is something that has been used in the past.
At the front of the car (above) more mixed heritage can be found with the Rebellion team apparently using headlights from the Peugeot 908 parts bin, possibly from the unraced hybrid of 2012 (below). However the newer car has its lights mounted differently and the upper section has a neat cutout in the shape of the Rebellion logo.
The front wing leading edge is clear to see, as are the Vulcan style brake ducts, partially taped up in this shot.
The rear wing main plane seems to have a slightly raised leading edge, as well as the now standard swan neck support.
At the rear the car features a large gurney between the wheel pods. Note with the left rear wheel removed its is possible to see right through the car from the rear. Again the general shape of the extreme rear of the car is similar to the ORECA 01, though being a coupe it does differ substantially in detail.
The wing mirrors on the R-ONE are nicely blended into the rear of the front wheel pod, an approach not seen on other LMP-1 designs. At the base of the leading edge of the front wheel arch there is a curious little turning vane, just visible below the ‘P1’ sticker.
A look under the engine cover of the R-ONE reveals the installation of the Toyota RV8K-LM engine, sitting quite low and forward in the car. The rear suspension is a conventional layout with pushrod actuated spring damper units mounted on top of the bespoke Xtrac transmission casing. The rear crash structure has been removed in this image.
Looking at the installation from the rear reveals that some of the loads from the roll hoop are transmitted to the gearbox casing with composite tubes.
LE MANS 24 HOURS
Shortly before the two Rebellions headed up to technical inspection it was announce that they would be running at 810kg, a 40kg weight break
2015 UPDATE & ORECA 05
At the start of the 2015 season Rebellion Racing opted to switch from the Toyota RV8K. The Japanese engine had long ceased production and the supply of parts had dwindled to the level that Toyota could no longer support the LMP1 version of it and the GT300 spec version used in the apr Prius. Retooling was not deemed worthwhile with a range of other Toyota engines in the pipeline.
Rebellion looked around at the available power units and opted for the AER twin turbo direct injection V6 (of currently unknown displacement) as seen above. The engine is shared with the current specification of the Kolles modified, Adess designed Lotus T128.
The new installation in the Rebellion saw the turbos mounted outboard in the side pods – with a new cooling layout featuring dual heat exchangers on both sides of the car (right side above, left side below).
The new installation also lead to a revised transmission, note the very neat bellhousing clearly a result of substantial FEA work at ORECA.
A nice look at the 2015 spec front bulkhead, note the master cylinders steering rack and torsion bars. The R1/ORECA 05 is one of only a few non works LMP’s to feature a torsion bar front end.
The Rebellion R1-AER features a distinctive twin entry air box mounted quite far back on the engine cover. The split is due to the box being so far back that the ORECA designers had no option other than to pass the mandatory fin through its centre. Looking at the internal layout of the pipework and plenum the separate entries on each side merge ahead of the air filter.
These layouts have been tried in Formula 1 but are rarely retained for long. It has been suggested that they give uneven airflow to the engine when the car is in yaw.
New cooling louvres have appeared on the top of the R1 side pods. Note the rearview mirror design.
A look at the control systems of the Rebellion R1 (above) and the rear suspension (below)
ORECA 05 Development & Comparison
Also at the start of 2015 ORECA introduced a new customer car for the LMP2 class. Dubbed the ORECA 05 the new car features the same chassis as the Rebellion, though almost everything else has been revised.
The front suspension concept carries over from the R1 as does the whole bulkhead concept, though the components used are made from lower cost materials.
The front crash structure is also a carry over part but the front aero, while visually similar, is significantly different to the Rebellion due to the differing regulations in this area.
The control systems of the ORECA 05 (above) differ substantially to those of the Rebellion even though both use the same core components such as the steering wheel housing.
Here we get a look at the rear end of the ORECA 05 with a Nissan engine installation. Note the spring damper layout of the rear suspension and the composite roll hoop supports connecting to the bell housing.
The engine air intake on the ORECA 05-Nissan is very conventional and essentially the same as that of the Rebellion-Toyota.
From the rear the family line from Courage LC70 to Rebellion R1 and ORECA 05 is clear. Indeed even between the aerodynamically different 2015 LMP1 (above) and 2015 LMP2 cars (below) the similarity of concept is striking. However notice the difference in rear wing width. The gurney difference is largely due to the LMP2 image being taken at Silverstone and the LMP1 at Le Mans.
At the front the differences are more obvious, though again the overall concept is similar. Both the Rebellion and ORECA 05 were designed purely in CFD.
Comparing the Rebellion Le Mans specific front aero dynamic package (above) you can see the twin front dive planes mounted below the headlight, as well as a small out board turning van on the leading edge of the front splitter. While on the LMP2 (below) the outer edge of the front splitter has an entirely different design with no turning vane and only a single forward projecting dive plane, though this has its own small turning vane.
In high downforce specification (below) the ORECA 05 also has a number of different elements used by its customer teams. The front splitter remains identical, but there are now two large dive planes with a slightly flared lower part of the wheel pod (compare the two Dunlop logos). Also the twin louvres at the leading edge of the wheel arch hole (air extractor) are not present in Le Mans trim.
The rear of the front wheel pod on the ORECA 05 (below) is a carry over of the concept used on the 2014 spec Rebellion that can be traced back to the later developments of the LC70.
2016
The Rebellion underwent a mild update for 2016, most notably including a switch to Dunlop tyres and suspension tweaks to get the best out of its new LMP1 product.
Aerodynamic development was primarily done using Ansys CFD software at ORECA (the image above is of the ORECA 05)
At Le Mans the Rebellion was fitted with its low drag aerodynamic package (above) which featured slightly re-profiled front fenders and new twin dive planes. At the start of the season it only ran a single plane (below).
While the Rebellion is allowed three aerodynamic upgrades per season in LMP1, its LMP2 sibling has a homologated aerodynamic package. Its high downforce and low drag kits are basically the same though with differing drive planes both of which can be seen earlier in this article. The headlights on the Rebellion have been revised for 2016 with LED clusters replacing the Peugeot 908 clusters ORECA found in the unused parts bin.
Because the two cars have been marketed very separately many people are still unaware that they are built around a common design and it is possible to convert one into the other. Compare the ORECA 05 front bulkhead (above) with that of the Rebellion (below), you will find very few differences.
note the electronic block just beside the master cylinders on the LMP1, absent on the LMP2, also the third element in the suspension is of a different design as in fact are the dampers.
A look at the Rebellion rear wing in Le Mans specification at the traditional test day grid line up.
Inside the Rebellion cockpit with most of the driver controls visible (we will post a shot taken from the other side of the car after scrutineering as well as the same angles of the ORECA 05) – note the screen facing away from the driver, its purpose is not clear as it can only be visible with the door of the car open. As it is next to the USB hook up for the engineers laptop it may be a engineers data screen.
At the start of the 2016 season Rebellion announced it would contest the full WEC with two cars powered by AER, “we will continue to use the AER P60 engine; last season it was a new installation in the Rebellion R-One chassis and whilst we achieved our target of taking the titles, there was still a lot of room for improvement on the reliability of the package. Together with AER we have been working hard on addressing the issues that came up in 2015 and we will make the necessary steps forward.” Bart Hayden said.
A look at the Nissan engine installation on the pair of (Renault) works entered ORECA 05’s which have been rebranded as Alpine A460’s. This project at one point could have morphed into a works Renault LMP1 programme had it decided to quit Formula 1 at the end of 2015. It is still possible that a variant of the Renault RE16 could find its way into the back of a prototype in future.
The AER engine had mixed success fitted to the R1, but it did provide good power offering the car a relatively high top speed.
AER’s engine (above and below) was one of four engines fitted to the ORECA tub, the others being the Toyota RV8K-LM, Nissan VK45DE and most recently the Gibson spec LMP2 V8.
At some races in the 2016 the Rebellion sported this neat little corner gurney on the trailing edge of the rear bodywork (below)
Here is a good look at the gearbox of the ORECA 05, very similar to that used on the R1.
2017: a third iteration
The ACO controversially changed the LMP2 technical regulations for the 2017 season, with only four chassis suppliers permitted in the class and only a single engine allowed. Curiously the ORECA 05 was the only existing chassis which could be adapted to suit the new regulations, fitting them perfectly before the new rules were published.
“The ORECA 05 was conceived in a record time with 2017 in mind. For that prototype we took into consideration most of what we knew of the 2017 technical rules at the time. That’s why the ORECA 05 was conceived with a width of 1900mm, instead of the 2000mm permitted by the current rules. This choice did affect the car’s performance, particularly on winding racetracks, but still was a good decision considering the overall scope of the project” Floury admits.
ORECA took advantage of this and rather than design an all new chassis (as Ligier had to) it decided to create an all new car on the basis of the ORECA 05/Rebellion chassis. The new car was called the ORECA 07.
“The ORECA 07 was conceived around the ORECA 05’s monocoque and shares a certain number of the 05’s mechanical components” Floury explains. “The idea was to build on the success and the quality of the ORECA 05 while developing performance. Our concept was to design a completely new car around a base of existing components thus allowing the teams who own an ORECA 05 to update it to the 07, by trying to control the cost of conversion. This is in keeping with the philosophy of cost cap and allows the teams to pay off their investments over a longer period. This approach imposed a few compromises compared to a scenario where we would have started the whole project from scratch. Yet it also presented several advantages. We have not made one single compromise as such, in terms of performance and packaging.”
Comparisons between the R1, 05 and 07 are inevitable so it makes sense to start at the front of the car.
The ORECA 07 (above) has an entirely new front impact structure compared to the 05 (below), the nose of the new car has an entirely different shape and aerodynamic concept. Whereas on the older car the nose was raised with a large duct underneath the 07 has a Toyota TS050 style low nose.
Note how different the nose shapes are, also note the slight raising and reshaping of the brake cooling ducts. Interestingly the front splitter concept has carried over and indeed can trace its roots right back to the ORECA modified Courage LC75 (below).
Behind the nose and front bodywork one of the most telling areas of any cars design can be found, the front bulkhead. There are notable differences in components between the R1, 05 and 07.
The R1 (above) was the first of the trio to appear, and as it raced in the LMP1 category used a number of higher specification components than the 05 (below). Note the different types of damper used.
The third design, the 07, retains the overall layout of the previous iterations but again there are component differences (below).
Le Mans 2017
David Floury describes the 2017 Le Mans update kit: “For this race only, the FIA and ACO have allowed LM P2 manufacturers to homologate a specific kit which price is regulated and cannot exceed 10,000€. This kit’s main objective is to reduce resistance in order to reach a good top speed and to improve performances in Le Mans. As for the ORECA 07, this kit essentially comprises new aerodynamics elements, both front and rear. They were mainly developed in CFD (digital wind tunnel), got tested and validated on Le Castellet track in November 2016, as part of development tests, and homologated in December 2016, as stipulated by the FIA. Additionally, it is important to note that rules & regulations do not allow to mix Le Mans and Sprint kits.”
The ORECA Le Mans update clearly works better than the offerings from Dallara, Ligier or Riley, with the cars dominating the pre race test. The Le Mans kit consists of a number of new or revised body panels. Immediately obvious is the removal and redesign of the front dive planes, with the Le Mans spec car sporting just a single element (below) compared to the WEC double element (above). 
Another area on the front of the car which has been changed slightly for Le Mans is the front wheel ‘air extractor’, these mandatory openings are designed to stop car flipping at high speed.
In WEC trim the ORECA is fitted with a lip on the leading edge of the hole (above) but this panel has been redesigned for Le Mans with the lip removed and a new leading edge fitted (below)
A neat design feature of the 2017 version of the car is the very curvy side panel, incorporating the exhaust exit.
Note the pair of tiny vortex generators just ahead of the rear wheel (below). Clearly a lot of effort was put into this region of the car by ORECA.
The front brake ducts on the ORECA are of some interest with a number of different blanking options on display.
Initially in WEC races the cars were all fitted with the version seen above, but at Le Mans a new variant was run during the pre-race test (below).
The base version has been seen in both the WEC and at Le Mans and is essentially just a small panel which does not blank off the duct at all. (below)
At Spa a different panel was used by some of the ORECAs taking part in that event (below).
And finally during the Le Mans test day yet another variant was in use. (below)
At the rear of the car one might expect to find significant differences between the WEC specification bodywork and the Le Mans kit but the differences are not great.
Compare the WEC rear bodywork (above) with the Le Mans spec (below) and the only major difference is the gurney.
Here is an unusual look at the rear bodywork of the ORECA from the inside looking outward.
The headlights of the ORECA drew attention during the Le Mans test. During daylight running the cars typically only run with the small LED clusters in the upper outside corners of the lamp pod illuminated.
But at times it appears that the clusters on the left do not always fully light up as can be seen comparing these two images. This is not something seen at either Silverstone or Spa, and seems to be a Le Mans specific issue.
During the Le Mans 24 Hours itself many of the ORECA 07’s in the field suffered lighting issues, not just with the headlights but also the number panels on the sides of the car as well as the LED tail-lights, especially on the left hand side of the cars. 
Here we get a good look at the Gibson V8 engine installation in the ORECA chassis, the latest in a long line of engines fitted to this monocoque design. 
