Lotus Renault GP: Fluid Inerter

Lotus Renault GP (LRGP) have been on one of the teams most innovative with their suspension over the past decade. As RenaultF1 They introduced the Tuned Mass Damper (TMD) back in 2006 and have since raced conventional Inerters. Inerters are a special component in the suspension to counteract spring effect of the Tyres\Suspension, using a spinning mass on a threaded rod to control these loads.

LRGP have also been one of the teams racing hydraulically interlinked suspension and have looked at other ways to legally alter the suspensions performance. It seems this work has lead to the discovery of a new form of Inerter, primarily using fluid for the Inerter effect. This new development has been termed by the team a “Fluid Inerter”.

A cross section of the patented Fluid Inerter

The intellectual property rights to this development have been safeguarded by Patent, allowing the details to be freely accessible in the pubic domain (the source for the picture at the top of this article). My attention was drawn to this development by Italian Mechanical Engineer Rodolfo De Vita, a specialist in Torsional Dampers and Dual Mass Flywheels (DMF).

Background
Becoming ever more complex the suspension in an F1 car has a number of devices to counter loads fed into the chassis, in order to maintain the ideal conditions at the tyre contact patch. We understand the role of springs and dampers, but there remain other spring effects within the suspension system, not least from the high profile tyres. Their spring effect goes undamped and hence is largely out of the control of the teams in setting up the car. Being able to counteract these uncontrolled forces in a suspension will allow the tyre to main better contact with the ground for more consistent grip. In 2003 Cambridge Universities, Dr Malcolm Smith proposed a mechanical method of controlling these loads via the Inerter. McLaren took up this idea and tested the idea in 2004 then went on to race an Inerter in 2005.
In size and construction the Inerter looks like any other damper. Being placed in the same position as a Heave Damper it was well hidden and unknown to most people. Until the “Spygate” saga in 2007, when the design was referenced as both the “J-Damper” and “a Damper with a Spinning Mass”. It wasn’t until May 2008 that I was able to understand and expose the details of the Inerter concept, publishing its details in Autosport.com (subscribers only http://www.autosport.com/journal/article.php/id/1554 ). Co-incidentally this article is cited in the patent documentation!

A Mechanical Interter

An Inerter can be configured in two ways: a linear and a rotary format. In both guises the device uses a toothed drive to spin a mass. Likened to the same effect as a bicycle bell, the load fed into the bells lever is dissipated by the spinning element. In F1 teams use a cylindrical mass screwed onto a threaded rod inside a damper body. One end of the rod is affixed to one side of the suspension and the damper body to the other side of the suspension. Reacting to the acceleration of the suspension, the Inerter absorbs the loads that would otherwise not be controlled by the velocity sensitive conventional dampers.

The Renault 2006 Front Tuned Mass Damper (TMD) - Copyight: Craig Scarborough

The Inerter predates Renaults TMD, which aimed to achieve the same effect. With the TMD a weight is suspended on spring to offset the same forces being fed into the chassis as the Inerter. Renault first raced the TMD in 2005, its discovery by Giorgio Piola around Monaco of that year; both forced a development race and an enquiry by the FIA. It was subsequently banned on what proved to be false grounds. The FIA citing a movable aerodynamic effect as the reason for its ban.
Unaware of its effect on the contact patch, I initially saw the device as a means to prevent the front wing pitching downwards when braking. The inertia of the suspended mass keeping the nose from pitching downwards during the initial braking phase. This I thought would prevent the car from being pitch sensitive. Despite a lengthy court room case, this “aero” function was upheld as the reason for the ban of the device.
Ironically the McLaren was using the Inerter at the time, and despite it being used for the same function was not banned and remains legal and in universal use to this day.

LRGP’s Fluid Inerter Concept
Reading the detail of the LRGP patent, it’s clear this was at least partly a surprise discovery. The Patent states the discovery was “based on lab testing of another hydraulic suspension device”, when it was found that the effect of the fluid within the system “has a very significant inertia effect”.
I would suspect this discovery was made during the development of the linked suspension system. Where fluid lines are used to link the suspension in a similar manner to the Mercedes system I detailed earlier this year (https://scarbsf1.wordpress.com/2011/10/17/mercedes-innovative-linked-rear-suspension/). Perhaps the longer fluid lines to link front and rear suspension provided the discovery, rather than the very short left to right linking pipework. I understand Renault have had hydraulically linked suspension on the car since at least 2009.
With this insight LRGP have proposed a Fluid Inerter using both the inertia of the fluid and a spinning mass. By making the Inerter device more like a damper, where by a damper rod displaces fluid; this fluid is then piped into a circuit to spin the mass. There by both effects can be created. It is the inertance of the fluid that differentiates the LRGP patent to the conventional Inerter proposed by Dr Malcolm Smith.
Inertance is a new term and I’ll quote the patent for LRGP’s explanation of the effect.
“Hydraulic fluid inertance means” concerns an arrangement in which the presence of a hydraulic fluid provides an inertance, where inertance is a measure of the fluid pressure which is required to bring about a change in fluid flow rate in a system. Between the terminals this translates to an inertial force which resists acceleration.
LRGP found that the fluid used was critical to the efficiency of the design. In particular to make it effective for the lightweight and small packaging volume required to make the device work within the tight confines of an F1 footwell or gearbox. Needing to be incompressible and low viscosity, they have proposed several fluids, such as water and oil, but the preference appears to be for Mercury. Although a metal, it’s liquid at ambient temperatures and very dense. This means smaller fluid lines filled with mercury will provide the necessary inertance, compared to larger amounts of less dense fluids. Passing from one chamber in the damper body via the fluid line to the other chamber, the detail design of the length and diameter of the fluid lines are key in creating the correct tuned inertance effect. Just “1 to 50g” of fluid is required to get the desired effect. The range of inertial reaction is quoted as “10 to 500kg, which is a typical range required in Formula One racing cars”.
As a side note McLaren decouple this inertial reaction force into different measured units. Rather than Kg of Inertial force, McLaren use the term “Zog”, this allows them to hide the actual units set up on their Inerter.
Renault suggests winding the lines around the damper body as one solution for the packaging of the fluid circuit. Additionally a valve or shim stack in the damper rod would also alter the amount of fluid displaced, to further tailor the Inerters effect.
With Mercury having a high coefficient of thermal expansion, the patent suggests using a relief valve emptying into another chamber is used to ensure the system has a constant volume of fluid.
Clearly the emphasis is on the fluid to provide the inertance effect, the patent citing a minimum 50%, up to as much as 90% of the inertance coming from the fluid.

In Detail

The device uses the left hand casing as the fluid cylinder & the right hand casing for bump rubbers

Not only does the Patent contain the conceptual information on the Inerter, but also detailed cross sections. I have simplified these to explain the Inerters construction. LRGP have been able to condense the entire solution into a single self contained component, which fits into the same volume as the conventional Inerter.
The device is made up of a main body and a damper rod. The main body split into left and right sections bolted together. The left hand casing forms the cylinder, not only contains the fluid, but also channels machined in the outer casing form the fluid lines. Such that no external pipework is required. The right hand casing allows the damper rod to pass through and also houses bump stops to prevent the device bottoming at the end of its 16mm of bump travel or 23mm of droop travel. In total the device is just 220mm long (eye to eye).
In cross section we can see the casing is a complex machined part. With the right hand chamber formed with bushes, seals and endplates to create the cylinder for the damper rods to pass through. The damper rod along with its shim stack valve pass through the cylinder like piston as the suspension compresses and rebounds. The mercury within is displaced and passes through channels into the channels machined into the wall of the body.

Installation

The Inerter (yellow) is mounted between the rockers

LRGP provide a diagram for the Inerters mounting. This being a typical position between the pushrod rockers. No doubt a similar mounting is found between the rear pull rod rockers. Externally it would be hard distinguish the Fluid Inerter from a Mechanical version. Albeit the Renault front bulkhead design shows almost nothing of the Inerter inside the footwell. The steering rack and anti roll bar getting in the way of the small aperture inside the front of the monocoque. Thus we cannot be clear if the device has raced.

Benefits
One benefit is the technology is proprietary to LRGP and not used under license via Penske or Dr Malcolm Smith. Thus LRGP are free to use and develop this technology freely.
I couldn’t state whether the Fluid Inerter has any compliance benefits over a mechanical one. Perhaps it’s easier to tune via the shim stack in the damper rod, rather than the fixed specification of the mechanical Inerter. Equally it may be easier to maintain, teams needing to strip clean and re-grease their Mechanical Inerters frequently to maintain their smooth operation.
It seems one advantage to this device might be lightweight. The tiny amount of fluid required would be lighter than an equivalent spinning mass. As Inerters tend to be mounted relatively high a weight saving will aid CofG height, as well as ballast placement.
One negative issue is that Mercury is a hazardous material. Considering the unit is positioned ahead of the driver’s legs, any mercury leakage as a result of a major accident will only complicate the health issues for the Driver and Marshalls. I am not aware of Mercury being specifically restricted by the FIA approved material list. Although with just a few CC’s of the liquid contained within the cylinder, this might not be regarded as an issue by the FIA.

Conclusion
However the team came across this solution, it is a new direction for Inerter development. The solution is totally legal, as set by the precedent of the mechanical Inerter being allowed to race, even when the TMD wasn’t
It will be interesting other teams come forward with new Inerter or linked suspension solutions. The only problem is few teams patent their design to allow us such insight to their design.

A view of the outer casing

A cross section of the Inerter

An exploded view of the parts

More references on Inerters

http://www.montefiore.ulg.ac.be/doc/smith09.pdf

http://www.ieeecss.org/sites/ieeecss.org/files/documents/IoCT-Part2-14FormulaOne-HR.pdf

Analysis: Rotary Dampers

The Rotary damper has been an innovation that has recently come and gone in F1. Typically F1 cars use Linear\telescopic dampers. However, in 2003 Sachs Race Engineering developed a Rotary version of a classic monotube damper for Ferrari. This was a tidier solution for packaging the dampers at the rear of the car. Since 2003 several teams have used Rotary dampers, Toyota, Midland and most notably Brawn GP. Who won the 2009 championship with these fitted at the rear of the car. I have recently come across a Rotary damper as fitted to the Midland car in 2006 and thus we have the chance to look into the detail of this development. I’ve also been in touch with two of the designers who have raced this device and they have given us some unique insight into its use.

Firstly John McQuilliam, who is now Designer for Marussia, but back in 2006, was the designer for Midland F1 (previously Jordan, latterly Spyker and Force India). The Midland M16 was the first of the teams’ cars to exploit Rotary dampers, as McQuilliam explains “I remember we were working with Sachs, as we had their Clutches on the car at the time. The Ferrari had Rotary dampers and it looked to be such a neat installation, we wanted to do something similar “. But this was not a total success, as their use on the Midland was short lived as they were replaced mid season with Linear dampers.

Secondly we have insight from the ex-Brawn Designer Jorg Zander, now running his own consultancy (http://jz-engineering.com/). As Honda were leaving F1 and the Brawn GP team was created, due to the Honda link the team had been using Japanese Showa dampers, but Zander was persuaded to switch to a Rotary design. As Zander recalls “Showa did a brilliant job and they would have provided us with continued support, but my boss was keen to go down the Rotary damper path with Sachs”. He adds that “the car still won the championship!”. Along with the Ferrari wins during their use of the Sachs Rotary damper, it’s clear that the technology has had a lot of success in F1. But it is still blighted by a reputation of being a troublesome technology.

Linear dampers
A conventional Linear damper is made up from a cylindrical body in which a damper rod slides in and out of (much like a bicycle pump). A valve at the end of the damper rod passes through the inside of the cylinder which is filled damper oil and the oil passing through the vales controls the rate of movement of the damper. Being cylindrical it is easy to machine in a lathe and oil is kept in place with simple circular seals.
The Dampers are installed on the car by one end being secured to the gearbox case, the other end to a rocker which re-orientates the movement from the pushrod into the movement of the damper. The rocker can be made up of several levers splined to a single shaft and requires several bearings to make the suspension movement friction free. This amasses into quite a lot of separate components which all need space to fit in.

Rotary Damper Anatomy

A top view of the Rotary Damper

Essentially the Rotary damper rotates the axial movement of the Linear damper into a Rotary movement. All the components have the same function, they just move in a different orientation. Thus the damper body is deep “keyhole” shape and the damper rod (known as the vane) rotates in the body, the vanes arm sweeping through a small angular rotation in the keystone section of damper body. The damping valves are placed in the face of the damper vane and work in exactly the same manner as a Linear damper.

Obviously the shape is the biggest difference and manufacturing the damper is far harder due to the fact that the parts have to be CNC milled and not spun in a lathe.

Its clear to see how the Vane moves inside the Casing to provide the Damping effect

Damper body

A view inside the cavity of the Damper Body

We can see the damper body is a robust metal housing machined from solid. Open on one side to allow the damper vane to be installed, there is a closing plate sealed with an “O” ring and 13 small bolts. To allow the damper vane to pivot the body features two bearings and seal arrangements, one on the closing plate the other is the main housing.

Damper body closing plate, with integrated Anti Roll Bar link mounting

As the housing also acts the suspension rocker, there are also elements machined into its outer face to accommodate this function. Firstly the housing acts as the rocker linkage, so a rocker arm is part of the machined shape. One of these eyes in the rocker will mount the heave damper and the other eye has bearing to accept the pushrod. Showing the packaging efficiency of the Rotary damper a further spherical bearing is fitted to a machined section of the cover plate. This accepts the Anti Roll Bar linkage. Thus for the Midland, no further suspension elements need to be fitted to anything but the damper housing. In the case of the all F1 Rotary dampers, the damper body rotates and the damper rod is fixed to the gearbox (via splines). As one part moves and the remains static, the vane moves through the oil filled cavity, the reaction force of these two parts creates the damping effect. To allow the damper body to rotate in the gearbox, two bearing surfaces are machined into the outer face of the housing and cover plate.


One additional external feature is machined into the damper body, a single damper valve. I believe this is a valve to compensate for the effect of heat on the volume of oil inside the casing. The valve offsets the thermal expansion of the oil to ensure there is a constant volume of oil within the damper cavity.

Damper vane

DLC coated Damper vane, the damping valve being bolted into the face of the arm

Inside the damper body sits the damper vane. This is a highly finished and possibly DLC coated component. Even when degreased this part had the feel of a lightly oiled component. The friction reducing coating being there to reduce the friction created by the vane moving inside the housing. Again machined (as most F1 parts are) from solid, the damper vane is formed of two shapes.
Firstly, the spindle that sits in the bearings that allows the arm to the rotate. One end of this spindle has splines machined into it.
Then secondly a flat plate shape is formed into the vane, this is the equivalent of the Linear dampers damping rod. This arm needs to be a close fit to the damper cavity in order to accurately control oil for the damping effect. It’s the edges of this arm that need to be sealed against the housing. A single square edged seal is fitted into a machined groove around the periphery of the vane. There are also four friction reducing pads (two on each side) to aid the movement of the vane against the body.

The three sides of the vane have a seal and friction reducing pads

Providing the damping effect the damper valve is a simply circular shim stack arrangement fitted to hole machined into the vanes face. This valve set up is almost identical to the set up used on the end of a Linear damper. This is perhaps the only aspect of the Rotary damper that directly echoes a Linear set up.

Installation

When installed on the gearbox the damper is clearly visible

As already alluded to, the Rotary damper is fitted to the gearbox casing and forms both the damper and the rocker. The damper vane slides into splines machined into the gearbox casing and a bearing locates on the bearing surface of the cover plate. Then another bracket fits to the rear of the gearbox to locate the rear bearing and secure the damper in place. The torsion bar passes through the damper engaging in splined in the spindle of the damper vane and also on the front face of the gearbox. Splines on the protruding section of the damper body are probably for the preload adjuster arm.

The Heave Spring and Anti Roll Bar are also mounted direct to the Damper

The pushrod passing up from the lower wishbone fits to the rocker, as does the heave spring\damper which sits over the top of the damper to attach to the other side damper. One end of the anti roll bar attaches to each spherical bearing and then the installation is complete.

Pros and Cons of Rotary Dampers
As explained the main benefit is the packaging of these units. Typically Linear dampers are operated by rockers and the dampers are then either laid across the top of the gearbox or sit vertically (requiring a recess in the top of the gearbox case). Either option carries complications in the cars structure or aero. With a Rotary damper the unit forms both the rocker and the damper and takes up far less volume.

As the damper vane permanently sits inside the casing, as the vane sweeps through the radial movement, no oil displaced. This is described a constant volume system. Unlike a monotube damper where the damper rod displaces fluid inside the damper body. This requires a method to offset the movement of the excess fluid. Typically separate nitrogen charged cylinder is used, the gas is compressed by the displaced fluid. But this in itself creates a small spring effect inside the damper. Other methods include the though rod damper, whereby the damper rod passes through both ends of the damper body, thus displacing no fluid. However through rod dampers do require additional seals and this creates some additional friction in the design.

Other key benefits of the simpler Rotary design are weight reduction, with fewer parts the 950g damper with its integrated rocker is lighter than a conventional damper and separate rocker set up. John McQuilliam confirms “We did achieve a weight saving over the conventional layout when you consider the damper, its drive arm and reaction bracket.” McQuilliam goes to on to highlight its packaging and resultant aero benefits “also the packaging is easier, without finding a volume for the damper. Akio Haga who is now alternating chief designer at Force India was laying out the rear suspension back then and we had a few different lay outs, mainly to try and keep the mechanicals out of which ever area the Aero was telling us was most important”.
With there being less parts to be splined together and less bearings in the Rotary design is also stiffer and suffers much less from slop. Jorg Zander explains “the good side of the Rotary damper is that because of the rocker integration, the system is very stiff and direct, so there is little losses due to backlash in linkages, ball joints, etc. which meant it had a good high frequency response”.

So with the damper being a constant volume design, structurally stiff, lightweight and easy to package why has it not become the norm for F1 suspensions?

There is a simplistic argument bandied about that the damping effect is the reason they do not work so well. Neither designer suggested this was the case to me, although at the time McQuilliam did suggest to me it was a factor, but corrected himself with hindsight “I think the damping was actually reasonable”. McQuilliam continues to highlight a more specific deficiency in the Rotary design, “there is a much more complicated sealing arrangement in the damper, adding stiction”. Stiction is one of the enemies of the suspension designer, a mix of terms meaning “sticky” “friction”. This is seen as initial friction, then smoother running. This non Linearity of response is hard to design out. Where as the inherent spring rate added by a gas charged damper can be considered in the overall suspension spring rate, stiction cannot. Zander also echoes this issue “However, the downside is that due to the high internal pressure, the hydraulic seals had to have reasonable preload, which induced a large amount of friction and hysteresis”. This internal pressure also lead to structural issues, the Ex Brawn designer tells me “the high internal pressures caused local deformation of the housing, as well as the vane, this lead to increased friction and pretty inconsistent damping characteristics. Initial developments started with Aluminium, then Ti and steel options to gain stiffness to reduce the issues caused due to deformation. The Midland Damper that I have appears to be titanium. This was an earlier design compared to the Sachs dampers run on the Brawn in 2009. It is possible to see the ribs machined in to the casing to reinforce the device from deformation.

Another argument quoted in the press is the small size of the damper, which results in a lack of oil or radial movement. I removed some 75cc of fluid from the damper and the damping chamber was quite large. The limited radial movement was not seen to be a major problem, being taken into account in the rocker sizing, although both designers point out it still had to be factored in. Zander explains “The angular displacement wasn’t so much of an issue in 2009 and in previous years, but with the heavier fuel loads from 2010 that should be something to be considered.” Seeing as the 2009 Brawn BGP001 was succeeded by the Mercedes W01, it’s interesting to note the latter went back to Linear dampers.

Away from the technical argument of Rotary over Linear there was one other factor which perhaps underlines the less publicised aspect of the designers’ role, budgets! But when we recall that Midland and Brawn were both teams managing a tight budget, this last issue makes sense. Both designers highlighted price as one of the major issues of the Rotary damper. McQuilliam starting by saying “They were mighty expensive, so not good value for money for the weight saving”. Zanders more recent recollection of the Brawn days provides this insight “I think a bigger argument against it for some teams, were the cost of such a Rotary damper. Depending on the specification, it was in the region of about €15.000 per piece”. With these being sealed dampers for each set up, a pair of dampers (€30,000) would be on the car and a multitude of other dampers pairs in the pits, each set up for different damping characteristics.

Conclusion
Clearly the stiction and internal stiffness issues need to be addressed with the design. Evolution via detail design has overcome similar issues with Linear dampers, so presumably the same could be resolved for Rotary dampers too.
The cost issue still remains; inherently they are a complex and high precision part. Where as turning on a lathe produces the correct finish for a Linear damper, careful milling operations are required for the damper body of the Rotary damper, which will inevitably make this an expensive part to produce. No doubt more teams using the damper would drive the price down.
It’s interesting to note that the Sachs Race Engineering website no longer details Rotary dampers as part of their range. Instead conventional Linear dampers and a Through-Rod version of the same, form the basis of their product range and their current Formula1 teams use these Linear format dampers.
Given the choice between Rotary and Linear, Zander sums up the decision well “I would at the current stage of damper technology development prefer Linear dampers over Rotary ones. The friction can be controlled in a better way and problems like cavitation are well understood and do not cause any issues in contemporary Linear damper designs. Also the flexibility with Linear damper designs is much wider, considering systems like: frequency depending damping, high & low speed damping, drop off characteristics (blow by valves, pressure relief valves)”.
Perhaps the Rotary damper will be explored in F1 again at some point, but for now the Linear damper is the sole solution in F1.

Front Anti Roll Bar Solutions

An excellent Sutton Images picture seen on F1Talks.pl, taken through the aperture on the front of the McLaren has given us a rare chance to see the set up of the front suspension.

(http://www.f1talks.pl/2011/08/25/czwartek-na-spa/?pid=4590).

Typically most teams follow the same set up for the front suspension in terms of the placement of the rockers, torsion bars, dampers anti roll bars and heave elements. As unlike with rear suspension, the raised front end almost dictates a pushrod set up in order to the get the correct installation angle of the pushrod. However the McLaren antiroll bar shows there is some variation in comparison to the norm and also highlights Ferraris similar thinking in this area.

In comparison to my more recent posts, this is not a breakthrough in design, simply a chance to see the teams playing with packaging to achieve similar aims.

Typical front suspension

As an overview of the conventional of the rocker assembly in the attached diagram shows the rockers are operated by the pushrod, a lever formed by the rocker operates each of the suspension elements. Compressing the heave spring and wheel dampers, extending the inerter and twisting the torsion bars.

A typical "U" shaped ARB: Arms connect the torsion bar to the rockers via drop links

Typically teams use a “U” shape anti roll bar (ARB). In this set up the antiroll bar is connected to the rocker via drop links, and then each arm twists the torsion bar when the car is in roll. When the car is in heave (car going up and down, no roll) the ARB simply rotates in its mounts and adds no stiffness to the suspension. Different torsion bars in the anti roll bar create different roll stiffness rates for the suspension. Teams will either switch the entire ARB assembly for a different rate ARB. Red Bull have engineered their ARB for the torsion bar to be removed transversely through the side of the monocoque, in a similar fashion to removing the normal torsion bars.
However McLaren and Ferrari have gone a slightly different route.

Mclarens ARB

McLarens ARB is formed of two blades joined by a drop link

In McLarens case their ARB is a simple blade type arrangement. These blades are splined to each rocker the blades are joined at their ends by bearings and a drop link.

In roll, the blades react against each to create roll stiffness

When in roll the rockers rotate in the same direction, one blade goes down and the other goes up, the stiff drop link transfers these opposing forces and the blades flex. These opposing forces add stiffness to the front suspension in roll.

In heave, the blades move together

In heave the rockers rotate in different directions, both blades move down and the increasing gap between their ends is taken up by the drop link. So the blades do not flex and do not contribute to heave stiffness.
Different thickness blades create different roll stiffness; they must be removed from the rockers and replaced to achieve this.

Ferraris ARB

Ferraris ARB uses two blades joined by an elegant arched guide

Ferrari have used this solution at least since the late nineties, the idea has been seen on older Minardis too. I suspect the idea was taken to Minardi by Gustav Brunner, who may also be the creator of this elegant solution.
Similar to McLaren the roll stiffness is provided by blades splined to the rockers. But the connecting mechanism is instead a single bearing sliding inside an arched guide. Just as with McLaren ARB, when in roll the two ends push against each other to create the reaction force to prevent roll. When in heave the bearing slides through the arc of the guide and no force is passed into the suspension.

Summary
I don’t believe either of these solutions has a compliance benefit over the other. The McLaren\Ferrari systems may be take up a little less space inside the nose and may weigh a little less. But both will be a little more complex when changing the roll stiffness.

Assemblies

A legal but flexible T-Tray Splitter: The ‘See-Saw’ solution

For over a decade, the FIA have tried to reduce front wing performance by increasing its ride height. Moving the wing clear of the track for less “ground effect”, reduces the wings efficiency and handicaps downforce. When the major aero rules changes came in for 2009, the loss of the central spoon section and the smaller allowable working surfaces for the front wing, made getting downforce from it even harder.
Through out this period, teams have sought to gain front wing performance, largely by trying to make the wing closer to the ground. Either via flex or by altering the attitude of the car (i.e. rake). As has been explained before in this blog, the issue with making the front wing lower by raking the car is that the T-Tray splitter gets in the way. Teams have sought to make the splitter flexible to allow it move up and allow for a lower front wing.
to combat this the FIA have a deflection test to ensure the splitters are not flexing and that front wing ride height is maintained. In response to accusations about several teams splitters, at Monza last year the FIA doubled the test to 5mm of movement for a 2000 Newton (~200kg) load. Yet in 2011 we still see cars with a nose-down raked attitude and wings nearly scraping the ground. How can a splitter meet the FIA deflection and still flex on track? I have a theory for a splitter construction, that actually exploits the method of the FIA test to provide the splitter greater stiffness during the test.

Background
Typically teams run splitters mounted to the underside of the monocoque. The splitter is often made from metal to act as ballast, with additional carbon fibre bodywork to form the aero surfaces. Beneath the splitter runs the Skid block (plank). Made to FIA dimensions the plank features holes for measuring wear.
The splitter is bolted securely to the underside of the tub by bolts and in some cases with a small strut at the leading to aid installation stiffness. Disregarding the strut, the splitter is effectively installed in a cantilever arrangement. The protruding section of splitter will need to bend upward when grounding on track or on the FIA test rig.

With a typical splitter, wear will occur only at the leading edge of the plank

With a car in a raked attitude, when on track the splitter will exhibit a classic wear pattern, the tip of the splitter will wear away in a wedge shape roughly equivalent to the rake angle of the car. During normal running, for cars with high rake angles its likely no other wear may take place along the length of the plank. If the car runs a front ride height that’s too low, the splitter will wear away leading to exclusion at post race scrutineering.

See-Saw Solution

A pivot half way along the splitter creates a 'see saw' effect

Rather than run a cantilever mounted splitter, my theory would be to run the splitter mounted on a pivot. Taking the length of the removable section of splitter, the pivot woudl need to be half way along its length. Which would be roughly inline with the heel of the monocoque. Not having any significant mount at the rear of the removable section of splitter would allow the splitter to pivot like a ‘see saw’.

With the 'see saw' splitter, grounding on track will bend the plank & create two wear spots.

Now when the splitter grounds on track, the leading edge will tilt up and the trailing edge tilt down. This ‘See-Saw’ effect, will allow a slightly lower front ride height as the splitter will be deflecting upwards. To achieve this the plank will need to flex, as the front section of plank must now be a minimum of 1m long, far longer than the splitter. The drooping trailing edge of the splitter will now make the plank contact the ground, leading to a distinctive wear pattern. Now having plank wear in two placed, beneath the splitters leading edge and the trailing edge. This will also have the benefit of spreading the wear over a larger area of plank and reducing the likely hood that the front inspection hole will be excessively worn. The fulcrum point need not be the overtly obvious pivot I have drawn and the entire exterior of the splitter could be covered in bodywork, which will have enough strength to keep the splitter in place when stationery, but deform enough to allow the splitter to ‘see-saw’. But in this guise the splitter will not have the strength to meet the 200kg load from the FIA test.  so how will it pass the test?

The current format of the FIA test, actually aids the pivoted splitter.

The FIA test is carried out on the multi functional rig that is used for the other regulatory checks. The car is driven up onto the rig and then steel pins protruding up from the rig, locate in corresponding holes in the plank. The sections of floor under the wheel are dropped away and the cars ~580kg (640Kg less driver) weight sits on its belly (the plank\reference plane floor).
Then a hydraulic strut with load and displacement sensors extends upwards beneath the front splitter. The 2000n load is applied and the deflection measured.

With a typical splitter the FIA load bends the splitter like a cantilever

For a cantilever splitter, the test tries to bend the splitter upwards straining on the bolts at its tail end.

For a 'see saw' splitter, the weight of the car is on one side of the fulcrum, making it harder to deflect the other end upwards

Where as for the ‘see-saw’ splitter the test tries rock the splitter, effectively trying to bend the splitter like beam about its fulcrum. But the cars weight is sitting on the tail end of the splitter, preventing the splitter tilting upwards. As long as the splitters beam strength is enough to meet the test, then it will pass. Being a long metal structure, it should not be hard to make the splitter strong enough.
So as the FIA tests the cars weight sat down on the splitter, it actually aids the splitters ability to beat the test. If the test were to apply the load to the splitter, when the car is supported on its own wheels and not its floor, then the car would surely fail the test.

Interpretations
The biggest flaw is this theory is the wording of article 3.17.5 which describes the test and the mounting of the splitter. But typically the FIA rules are both vague and overly specific at the same time. The regulation states that mounting between the “front of the bodywork on the reference plane” and the “survival cell” (Monocoque) must be not be capable of deflection. The definition of “front of the bodywork” might mean its leading edge, but might not incorporate stays further back along the car. Equally the design of the fulcrum need not be the pivot I drew, but a simpler solid but flexible part, that is not suspected to deflect.
As with all borderline legal parts, this would need to be carefully assessed against the wording of the rules. But where’s there’s ambiguity, there’s a chance to exploit.

The legal interpretation of the regulations not withstanding, this is a feasible solution.  The biggest risk to running it, is if the FIA change the test process without notice.  This could catch the team out, although normal FIA process is to warn the team and ask for the design to be altered and pass the test at the next event.  Thus unlikely to cause an exclusion or  ban.

 

Footnote: A team have asked the FIA for clarification on the use of this splitter construction with a view to using it themselves.  Charlie Whiting has made it clear it would not be and added that the deflection may now be altered to ensure the rules and test are not being exploited.

Pitstop set up adjustments during the race

During most races we see the mechanics make adjustments to the car during pitstops. During each stint radio communications between the driver and his race engineer will discuss the cars balance. Whether the car tends to oversteer or understeer. Since the ban on active technologies there’s little the teams can do to alter the car during the race. Currently only front wing adjustment, rear wing gurney removal and tyre pressures are easily changed during the hectic 3-4s pitstops.

Front wing adjustment

Front Flap Adjuster (arrowed)

This is the most flexible and simplest adjustment, during the stop the mechanics can raise or lower the front flap, via threaded adjusters in the mountings. Known as FFA (front flap angle), a greater angle will reduce aero induced understeer and less FFA similarly reduces oversteer. The race engineer will call for the mechanics to make so many ‘turns’ of wing. A ‘turn’ is quite simple a 360-degree rotation of the adjuster screw. One teams ‘turn’ will not necessarily be the same as another teams, as the wing\adjuster geometry will be different for every team.
Teams have historically used a cranked handled wrench for this purpose, although teams have recently been using cordless drill type adjusters. The collar of the drill modified to quickly deliver a specific number of turns, which are pre-set into the collar mechanism.
Between 2009 & 2010 drivers had the option to use the adjustable front wing flap mechanism. Allowed in the rules in 2009 as a pre-DRS overtaking aid. Although the idea did not really aid overtaking, teams did use it for the driver to alter balance during practice and in race stints.

Rear wing adjustment

A 'taped-on'Gurney flap (arrowed)

Although common in US single seat racing, rear wing adjustments are not common in F1. No team runs a threaded flap angle adjustment mechanism, preferring multiple ‘holes’ in the endplate to screw the flap into or machined inserts providing similar adjustment. In rear wing parlance, a ‘hole’ is also one unit of wing adjustment, similar to a turn of FFA. Clearly unfastening, repositioning and re-fastening a rear flap is impractical in a pit stop. However rear downforce is also tuned via the gurney flap, an “L” shaped strip along the trailing edge of the rear wing. By switching the gurney for a taller or wider strip, downforce can be increased. These strips are attached simply by tape, so are quickly removed. However fitting one does take time, requiring the wing surface to be clean and often heat guns are used to ensure the adhesive tape is sticking properly. Due to this, in the race teams are largely faced with the only option of removing a gurney and not adding one. Typically teams will add a more powerful gurney for a wet race, if the race dries then the teams will remove it. Less gurney will also decrease drag slightly and hence boost top speed.  Removing a gurney is a relaiutrvely simple process, as the strip is taped to the wing only via its leading edge.  The mechanic standing behind the wing pushes the gurney forwards and then rip sits off at an angle, taking the tape with it.
In the 2011 Suzuka Grand prix Felipe Massa was reporting understeer and his race engineer Rob Smedley radioed “Ok, we will do that rear wing thing”. At Massas subsequent pitstop, the rear wing gurney was removed. Reducing rear downforce to balance the car.

http://www.f1talks.pl/?p=11461&pid=5892

A Ferrari mechanic attaching a gurney with tape (via F1talks.pl & sutton images.com)

Tyre pressure adjustment

Wing adjustments are largely affecting medium to fast turn performance, at lower speeds the wings are less influential and the mechanical grip needs to be altered. Since the 1994 ban on active technologies, the drivers have no ability to alter the cars suspension. Before that drivers typically had the option to alter anti roll bar stiffness from levers in the cockpit.
So now the teams are left with just the option to alter tyre pressures in the race. Just as with wing adjustments, tyre pressure changes at the front or the rear alter balance. Again ahead of the pitstop the driver and race engineer will agree the change and the new set of tyres will be prepared in advance, pressurised to the right PSI.
During the 2005 season with no tyre changes teams had the mechanics with back pack mounted nitrogen cylinders, as the car stopped for refuelling, the mechanics would rapidly alter the tyre pressures to change the balance of the car.

Other changes during the race
While major balance changes are possible with wing and tyre pressure changed only at the pitstops, the driver does have some other methods to alter the cars balance, from the cockpit. Brake bias is a common adjustment allowing the driver to alter the brake bias front to rear. This can alter the turn-in to corners, as well as tune brake temperatures and locking wheels.
KERS harvesting (charging the batteries under braking) will also have a similar effect as brake bias. Drivers can alter this setting from the steering wheel.
More influential is the differential; this will alter the car at all three points in a turn; entry\mid\exit. A tighter differential will aid traction out of turns, but induce understeer going into them. Drivers will be altering each of the three settings to get the correct, mechanical set up to balance the car.
One area that’s been much talked about this year is the engines overrun settings. But these settings have been used for much longer to manage corner entry balance. How the engine behaves when the driver is off the throttle going into turns affects the rear tyre grip. A stronger overrun setting will create more engine braking, dragging the rear axle slightly on turn in. Which can make an oversteering the car more stable. Conversely softer overrun setting will suit an understeering car.
Lastly throttle and engine maps will affect the car on corner exit. Intuitively fiercer maps will make a car want to oversteer out of turns, offsetting understeer.

Red Bull – Monza Diffuser Analysis


Red Bull appeared in Monza was a further development of their diffuser. Changes largely appeared to be focussed on the treatment of the trailing edge of the bodywork. For Monza the diffuser gained a flap around almost the entire periphery of the trailing edge.

Highlighted in Yellow, RBR had a flap spanning around most of the diffusers trailing edge

This flap has been used above the diffuser since the start of the season, but the flap has been narrower, being only fitted in-between the rear wing endplates. As explained in my analysis of the floor as seen at Monaco (https://scarbsf1.wordpress.com/2011/06/08/red-bull-monaco-floor-analysis/ ).

Many pictures were taken of the flap now extending around the sides of the diffuser, which I tweeted about during the Monza GP weekend. But it was the fan video taken during the race, as Mark Webbers stricken RB7 was craned off the track that has shown the floor in greater detail. The video posted on Youtube.com by atomik153 and seen here (http://youtu.be/swoomrzECdM ). This clearly shows the floor from about 3m 40s into the clip. Obviously this must have been unpleasant for Red Bull as the floor is so clearly visible, I know that the other teams have seen this clip. Many fans having seen the detail at the back of the diffuser and suggested the slot created around the diffuser was some form of double diffuser or cooling outlet. While the pictures might suggest this, the slot is merely the gap between the aerofoil shaped flap and the diffuser.  This following illustration shows how the flap is actualy shaped.  There are two parts; the new curved side sections and the pre-existing top sections.

When exploded, you can appreciate how the new bodywork forms a flap around the diffuser

Diffuser trailing edge theory

Few ideas in F1 are new, merely older ideas reinterpreted and expanded upon. This flap is not a new idea, its merely an extension of the gurneys teams have been fitted to the trailing edge of downforce producing devices since the sixties. Gurneys have been added to the end of a diffuser to aid the low-pressure region above and behind the diffuser. This practice has been increasingly important with the limit on diffuser height and other rules banning supplementary channels such as the double diffuser. As far back as the late nineties teams replaced this gurney with an aerofoil section flap. Notably Arrows and latterly Super Aguri used flaps placed above the diffusers trailing edge.

The need for this sort of treatment at the back of the diffuser might at first be confusing. A diffuser is a part of the underfloor, by accelerating air under the floor, low pressure is created and thus downforce is generated. With so many restrictions on the geometry of the floor and diffuser, teams cannot simply enlarge the diffuser for more performance. So they are forced into working different areas of the device harder for the same effect. One area is maximise pressure ahead of the floors leading edge, the other is the lower the pressure behind the trailing edge. This helps flow out of the diffuser, to maintain mass flow under the floor. Although the rules limit the height of the diffuser, this is only the height below the tunnels to the reference plane. Teams have a small amount of space above the diffuser for bodywork and the common gurney fits into the area. Gurneys work by creating a contra rotating flow behind the upright section, this creates low pressure and helps pull airflow from beneath the wing. On a diffuser this has the same effect as a slightly higher diffuser exit.

A gurney creates low pressure by the contra rotating vortcies behind the gurney

The gurney can work above the diffuser, as teams have been paying so much attention to getting high pressure air over the top of the diffuser. This airflow is used to drive the vortices spiralling behind the gurney flap. The better the airflow over the diffuser to the gurney the more effective it can be.   However Gurneys cannot be infinitely increased in size and still maintain their effect. As the gurney gets too large the dual vortices break up and the low pressure effect is lost. Many teams have found this limit this year and have moved to the next solution which is a perforated gurney.

A perforated gurney can be larger as it's offset from the diffuser allowing airflow to pass under the gurney

This is a similar vertical device fitted to the diffusers trailing edge, but there is a gap between the bottom of the gurney and the diffuser. Airflows through this gap to create the distinctive contra rotating airflow behind the gurney. Again this has the same effect as creating a larger diffuser exit and hence creates more downforce.

An aeroil shaped flap can be larger and more efficient than a Gurney

While the gurney is a relatively blunt solution, Such is the quality of the airflow over the diffuser now that teams are able to fit a more conventional aerofoil shaped flap above the diffuser for a similar effect. Without the contra rotating flow of the gurney this solution can be scaled up, as long as the flow to the flap is maintained. Many teams have this solution fitted along the top edge of the diffuser. Although Red Bull are the only teams to have fitted to the side of the diffusers trailing edge. Increasingly teams are seeing the diffuser exit as a 3D shape, the diffuser not only diverges vertically at the exit , but also laterally. No doubt exhaust blowing does allow some of these devices to be effective.

In Detail: The flap on Red Bulls diffuser

We can expect its use to be expanded for next year with larger flaps above the diffuser and flaps around the entire periphery of the diffuser. A long with Rake this will be a critical design feature for 2012, as a result sidepod design will become one of the critical factors in aero design, making sure the top of the diffuser is fed with good airflow. As so few other areas provide potential gains for improving aero efficiency.

Other notes on the Red Bull Floor

Fences

Red Bull fit three fences in each side of the diffuser, these prevent different pressures regions migrating from one side of the diffuser to another. They help maintain downforce and sensitivity. Its interesting to note the fences are not triangular in side profile, I.e. that they don’t meet at the kick line between the floor and diffuser, instead they start a few centimeters behind the axle line with a rounded vertical leading edge.

Starter Motor Hole


As mentioned in the Monaco RBR floor analysis the starter motor hole is blown by ducts in the upper side of the floor. This injects some energy into the flow in the middle of the diffuser. This so called boat-tail section is where the steeped underbody merged with the higher step plane. With the lower centre section and plank, getting airflow into the area is difficult and separation can easily occur if the angle of the floor is too steep. Having the starter motor hole blown helps maintain airflow in this area.

Metal Floor

Exhaust Blown Diffuser Flow

Book Review: Haynes Red Bull Racing F1 Car

When Red Bull Racing launched their new car for 2011, the event was marked by a very special press pack. The pack was formatted in the style of the well-known Haynes maintenance manuals (PDF). This in itself this was a great book, but almost unnoticed within its pages was the intended publishing of a complete Haynes style workshop manual on the RB6 car.
Now some six months later the Haynes Red Bull Racing F1 Car Owners Workshop Manual (RB6 2010) has been published. As its rare a Technical F1 book is published, not least one with insight into such a current car, I’ve decided to review the book in detail.

Summary
At 180 pages long the book has enough space to cover quite a wide range of topics and it does so. Starting with a background to the team, moving on to the cars technology, to overviews of its design and operation. With its familiar graphical style and hardback format it certainly gives the feel of a proper workshop manual. However this is somewhat skin deep and the pages within, soon revert to a more typical book on F1, although some flashes of the Haynes style do remain.

Steve Rendle is credited as the writer of the book and Red Bull Racing themselves have allowed close up photography of the car and its parts, as well as providing a lot of CAD images.
But clearly a lot of editing has been carried out by Red Bull Racing and the book falls short of its presentation as a manual for the RB6. Despite its confusing title, the book is probably better described as a summary of contemporary F1 technology from the past 3 years.
As the last in depth technical F1 book was the heavy weight title from Peter Wright showcasing Ferraris F1 technology from 2000, this remains a useful source of recent F1 technology.
This places the books target audience, somewhere between the complete novice and those already of a more technical mindset.

Anatomy

With forewords by Christian Horner and Adrian Newey, the opening 21 pages are a background to the team and detail of the 2010 season that brought RBR the championships. Then starts the core 100 page chapter on the cars anatomy, which opens with a pseudo cutaway of the car showing a CAD rendering of its internals.

Firstly the monocoques design and manufacture is covered, with images of the tubs moulds being laid up and CAD images of the RB4 (2008) chassis and its fuel tank location. Although little is made of the fuel tank design.
Moving on to aerodynamics, the text takes a simplistic approach to explaining aero, but there is an interesting illustration of the cars downforce distribution front to rear. This does highlight the downforce created by the wings and diffuser, but also the kick in downforce at the leading edge of the floor, but this is not adequately explained in the text. Mention is made of the front wing and the flexing that RBR deny, this is explained with a simple illustration showing the deflection test. The driver adjustable front flap, which was legal during 2009-2010 seasons, is explained, in particular that the wing was hydraulically actuated. When I understood that in 2009, only Toyota used a hydraulic mechanism over the electric motor system used by all other teams. In trying to explain the nose cone, the text and an illustration show a high nose and low nose configuration, but does not remark why one is beneficial over the other.

This section also covers very brief summaries of bargeboards, sidepods and the floor. Some nice close up photos of these parts included, but again with little explanation. An illustration at this point highlights the other FIA deflection test altered in 2010, which was aimed at Red Bulls alleged flexing T-Tray splitter. In this section the text cites Ferraris sprung floor of 2007, but not the allegation that RBR’s was flexing in 2010. A further simple graphic illustrates the venturi effect of the floor and diffuser, and then the text goes into simple explanations of both the double diffuser and the exhaust blown diffuser.
Having been one of the technical innovations of 2010 and since banned, the book is able to cover the F-Duct is some detail. A complete CAD render of the ducting is provided on page 53; this shows an additional inlet to the drivers control duct that was never visible on the car. This extra duct served the same function as the nose mounted scoop on the McLaren that introduced the F-Duct to F1.
Thus with aerodynamics covered in some 23 pages, the text moves onto suspension and the expectation of detail on the RB5-6’s trademark pullrod rear suspension. After a summary of the purpose of an F1 cars suspension, Pages 58-59 have some fantastic CAD renderings of front suspension, uprights and hub layouts. However the rear suspension rendering stops short at the pull rod and no rocker, spring, damper layouts are detailed. Hardly a secret item, so lacking this detail is let down for a book announced as an RB6 workshop manual. A lesser point, but also highlighting the censorship of some fairly key technical designs, was the lack of any reference to Inerters (Inertia or J-Dampers), The suspension rendering simply pointing to the inerter and calls it the ‘heave spring’, while naming the actual heave spring damper as simply another ‘damper’. Inerters have been in F1 since 2006, predating Renault’s mass damper. Their design and purpose is well documented and shouldn’t be considered something that needs censoring. It’s also this section that fails to showcase the RB5-6 gearbox case. Instead using a pushrod suspended RB4 (2008) gearbox, albeit one made in carbon fibre.
The steering column, rack and track rods are similarly illustrated with CAD images. This usefully shows the articulation in the column, but little of the hydraulic power assistance mechanism. Page 67 starts the section on brakes, again fantastic CAD images supply the visual reference for the upright, brake caliper and brake duct design. As well as a schematic of the brake pedal, master cylinder and brake line layout of the entire car. A nod to more typical Haynes manuals shows the removal of the brake caliper and measure of the Carbon disc\pad. A further CAD image shows the brake bias arrangement with both the pivot at the pedal and the ratchet control in the cockpit for the driver to alter bias.
Although not a RBR component the Renault engine is covered in the next Chapter. An overview of the complex engine rules regarding the design and the specification freeze kicks off this section and cites the tolerances and compression ratio for a typical F1 engine. Pneumatic valves, for along time an F1-only technology are explained, but even I failed to understand the schematic illustrating these on page 77. Also covered in the engine section is some more detail on the fuel, oil and cooling systems. With useful specifics, like capacity of the oil system at 4 litres and water coolant at 8 litres. Again some nice CAD images illustrate the radiators within the sidepod. Many sections have a yellow highlighted feature column; this sections feature is on the engine start up procedure, one of the mundane, but rarely talked about processes around an F1 car (other features are on the shark fin and brake wear). As KERS wasn’t used up until 2011, this topic is skipped through with a just a short explanation of the system.

Moving rearward to the transmission system, the old RB4 gearbox makes a reappearance. Again this disappoints, as some quite common F1 technology does not get covered. Page88 shows some close up photos of a gear cluster, but this is not a seamless shift gearbox. In fact seamless shift isn’t mentioned, even though it made its RBR debut in 2008, the year of the gearbox showcased in the book. I know many will highlight that this might be a secret technology. But most teams sport a dual gear selector barrel, each selector looking after alternate gears to provide the rapid shift required to be competitive in F1. So I think this is another technology that could be explained but hasn’t been.
Tyres, Wheel and Wheel nuts get a short section, before the text moves onto electronics. A large part of the electronic system on a current F1 car is now standardised by the Single ECU (SECU) and the peripherals that are designed to support it. So this section is unusually detailed in pointing out the hardware and where it’s fitted to the car. From the tiny battery to the critical SECU itself. Other electronic systems are briefly described from the Radio, drivers drink system to the rain light.
Of critical importance to the modern F1 car are hydraulics, which are detailed on p105. As with the other sections, CAD images and some photos of the items themselves explain the hydraulic system, although there isn’t a complete overview of how it all fits together.
Rounding off the anatomy chapter is the section of safety items and the cockpit. The steering wheel and pedals are well illustrated with CAD drawings and keys to the buttons on the wheel itself and on the switch panel inside the cockpit.

While I have pointed that the hardware shown in the anatomy chapter isn’t necessarily of the RB6, what is on show is obviously genuine and recent RBR. So for those not so familiar with the cars constituent parts, there isn’t a better source of this available in print today. Even web resources will fail to have such a comprehensive breakdown of an F1 car.

The Designers view

Moving away from the Haynes format of a workshop manual, the book then moves into a chapter on the cars design, with comments from Adrian Newey. It details the Design Team structure and some of the key individuals are listed. The text then covers the key design parameters; centre of the gravity and the centre of pressure (downforce). Plus the design solutions used to understand them; CFD, Wind Tunnels and other simulation techniques. Each being briefly covered, before similar short sections on testing and development close this chapter.
Although the text makes reference to creating ‘the package’, something Newey excels at. This section doesn’t provide the insight into the overall design philosophy, which one might have hoped for.

The Race Engineers view
Where as the Designers view chapter was limited, the race Engineers section was a little more insightful into the rarely talked about discipline of getting the car to perform on track. The process of setting up the car is covered; from the understanding of the data, to the set up variables that the race engineer can tune; suspension, aero, ballast, gearing brakes and even engine. Usefully the grand prix weekend is broken down onto the key events from scrutineering, to running the car and the post race debrief. Feature columns in this chapter include; Vettels pre race preparation and the countdown to the race start.

The Drivers view
Ending the book is an interview style chapter on the driver’s time in the car, mainly the driver’s perspective from within the cockpit when driving the car on the limit and the mindset for a qualifying lap. A simplistic telemetry trace of a lap around Silverstone is illustrated, although there is little written to explain the traces (brakes, speed and gear), this is accompanied by Mark Webbers breakdown of a lap around the new Silverstone circuit.

In conclusion
When I first got this book, I was constantly asked if it was worth the purchase or if I’d recommend it. If my review is critical at points, it’s mainly because some technology that could have been covered wasn’t. Or, that the content falls short of the books title suggesting it was a manual for the RB6.
Those points aside, I have learnt things from this book. Like details of the F-duct system, the Front Flap Adjuster and a wealth of smaller facts. There isn’t a better book on the contemporary F1 car. In particular the CAD drawings and close-up photos, just simply aren’t in the public domain. From the pictures we got over the race weekends, we never get to see half the hardware and design work that’s pictured in this book. So I’ll keep this book on hand for reference for several seasons to come.

Overall I’d recommend this book to anyone with a technical interest in F1.

Many thanks to Haynes Publishing who have allowed me to use their Images and PDFs to illustrate this article

This book is available from Haynes

History: Periscope Exhausts

Following the meeting of the Technical Working Group, the FIA have agreed to mandate periscope style exhausts from 2012. This has been in an effort to rid the sport of exhaust blown diffusers, a trend that has dominated aero development in 2010 & 2011. While initially it was the FIA’s intention to move exhausts to the rear of the diffuser, the teams preferred to route the exhaust out of the top of the sidepods “periscope” style. This solution is far more aero neutral and prevents teams developing new complex exhaust routing to gain what little aero advantage there is from the rear exit. Also it benefits the engine suppliers who don’t have to retune their engines for long secondary exhaust pipe lengths.

It’s interesting to note the history of the periscope exhaust, as this was at first a retrograde step in aerodynamic development. Historically F1 cars ran their exhausts straight out of the back of the car. Only the introduction of ground affects and turbo engines forced a packaging rethink to exhausts routing through the top of the engine cover. When ground effects were banned and teams sought to find some aero gains at the rear, it was Jean Claude Migeot, who was then the head of aero at Renault, doing the exhaust blown diffuser solution in 1983. This trend continued through the late nineties, when F1 engines were normally aspirated and the V10 format became the trend, as were ever higher rev ceilings. Teams were finding the aerodynamics sensitive to throttle position and slowly they started to move the exhaust away from the diffuser kick line and towards the trailing edge to reduce this sensitivity. This necessitated quite long secondary exhaust pipe lengths (the single pipe section leading from the multipipe collector). This passed the exhaust in close proximity to the gearbox and hydraulics as well as the rear suspension, which at the time was starting to be made form carbon fibre. Back in ate nineties materials were not as advanced as they are now and heat resistant materials were not as effective.

In 1998 this forced Ferrari into a rethink of the exhaust solution. Head of Aero at Ferrari at the time was Willem Toet, he explained to ScarbsF1 how the periscope came to be. He starts with an honest explanation “I was sort of forced into the periscope exhausts at Ferrari”. At the time Ferrari were developing their 90-degree V10 engine, seeking to find higher revs to regain the power lost from the more powerful V12s. This engine developed was the catalyst for the move according to Toet “Long pipes didn’t suit the engine at all so we needed to go short”. Unable to create the long secondary pipes the traditional rear exits were unviable, however their first solution was not immediately the periscope, “We found the best solution, quite an aero gain at the time, was to exit the exhausts out of the sides of the bodywork beside and ahead of the rear tyres with an extra panel to protect the tyres from hot exhausts. That’s how the car was launched”. This solution met the initial aero and engine development targets, but was not without its problems, as Toet adds “The materials available at the time weren’t so advanced and we had mechanical grip and driver feel problems associated with the rear suspension, still steel on the Ferrari in those days, deforming under temperature. We were forced to abandon this due to the handling feel of the car”.
Again the workaround was not the periscopes “We went to a simple blown diffuser but the performance loss was “noticeable”. We then tried a short pipe leading into but not connected to a secondary pipe but had some fires due to exhaust flame outs off throttle that then caused problems”. With other solutions finally exhausted Toet shifted to an up and out exhaust solution, which we tend to call periscopes, but he terms snorkels. Toet concludes “And so the exhaust snorkels were born. Then with lots of optimisations we got them to work quite well (not as good a solution aerodynamically speaking as the side exits but not bad in the end). The solution then allowed for tighter rear bodywork which began to bring further benefits”. Looking at the rear of the 1998 Ferrari F300, the first design of periscope stood the test of time and in concept hasn’t changed much in the ten subsequent years. Ferrari of course had initial problems with the periscope design. Although the shorter exhaust bundle kept the radiated heat away from the side of the gearbox, where the suspension and hydraulics are packaged. But instead the hotter exhaust plume played over the rear bodywork of the car and critically over the suspension. Ferrari suffered suspension problems despite their early attempts at heat reflective materials being added to the upper wishbone. Detail development continued and by the end of the season Ferrari had proven the periscope was a workable solution.

F300 periscope exhaust, courtesy of Gurneyflap.com

It was a while before other teams followed the periscope solution. As their engine suppliers demanded shorter pipes, their carbon fibre suspension struggled with the heat and the throttle sensitivity upset the handling. So eventually every team switched to the up and out solution. By 2001 nearly all teams had gone this route. Leaving just Minardi and McLaren with blown diffusers. Minardi exiting their exhaust relatively high up over the trailing edge of the diffuser, at the time technical director Gabrielle Tredozi told me this was to reduce heat rejection and throttle sensitivity. However the team did trial some low exit exhausts, similar to McLarens at the high speed tracks of Indianapolis and Monza. But for 2002 the Asiatech V10 engine Minardi were to use demanded shorter exhausts and Minardi went for the periscope design with the Gabrielle Tredozi designed PS02.
Up to the 2001 MP4-16 Adrian Newey at McLaren directed his exhausts low down through the central boat tail of the diffuser. But in 2002 Newey was forced to go with periscopes, as he explained to me in my first ever interview with him in 2002 “The 2000-2001 cars had the same engine, we now have new engine, and different V angle that’s obviously changed, some of the packaging of the car the engine also has some different requirements, which is affecting us. Requests from the engine supplier Ilmor were different exhaust system requirements which meant we could no longer continue with putting the exhausts exits out through the floor so we had to go for top exits”. I pressed him if this was purely for engine demands, which he confirmed, but when asked if it was specifically for shorter pipe lengths he cautiously replied “I’d rather not go into details; we couldn’t accommodate what was wanted”.
So by 2002 every team had exploited the less sensitive, but aerodynamically inferior periscope design. It seems the effect of blowing the top rear wing or beam wing was of little advantage with the periscope design. However the trend in the 2000’s was for ever tighter sidepods, the periscope design enabled teams to go much further with the slimness of the coke bottle area as the pipes no longer needed to exit rearwards through the tail of the sidepod, they could be packaged further forwards in the sidepods. Slimmer and slimmer rear ends were developed, all to the benefit of the diffuser airflow, which in itself reaped aero gains. Initially the teams had the exhaust collector point upwards, with the short secondary pipe pointing up the turning 90 degrees to exit rearwards horizontally. As sidepod heights and widths reduced it became better to point the collector forwards and curl the secondary pipe in a “U” bend to point backwards. This placed the bulk of the exhaust system above the radiators and left very little volume to the side or behind the engine, to the benefit of the slim rear aerodynamics.
During the 2000s teams continuously varied the exit format of the exhaust. At some points during the decade an oval exit was used with a small horizontal stiffener added for strength. Also the exit varied between flush to the sidepod surface and protruding through the bodywork. Ferrari adopted a protruding exhaust, surrounded by a tall fairing that aided the extraction hot air from the sidepods. Some teams also exploited the hot exhaust for rear tyre temperature. Jordan exited their exhaust high and wide through the flip up ahead of the rear wheel. They had optional exhaust pipes that sent more of the exhaust plume over the rear tyres to increase their temperature. Renault also briefly tried a scoop that caught some of the exhaust plume and directed it over the rear wheel.
Then in 2010, it was Adrian Newey who returned the exhaust position to low down on the RB6, in order to exploit the fast moving exhausts gasses passing over and through the diffuser, the Exhaust Blown Diffuser was reborn. Several teams discarded periscopes during 2010 for low exhausts. But for the start of 2011 every team had gone for a low exit and the periscope disappeared. It appeared as though it was lost from F1. Now with its mandatory renaissance in 2012, it will be interesting to see if teams can further develop this simple concept further.

History: BAR Honda 2-3 Element Rear Wing

copyright: Craig Scarborough

Looking at the Ferrari Spanish GP rear wing with its literal interpretation of the slot gap separators, it brought to mind another rear wing designed to work around the rules. Back in 2004 the FIA introduced a further limit on upper rear wing elements, going down from three to just two elements, a rule that stands to this day. In 2003 teams ran with what was often called a bi-plane rear wing. That is the three elements were mounted as: a two element wing (main plane and flap) and a further element cascaded above them. When two elements were mandated, the wording in the technical regulations was vague and defined what constituted the two closed sections by defining how large a space was allowed between them. This left some opportunity for a different interpretation. Willem Toet was then the Head of Aero at BAR Honda, he and his design team found a way to make a three element wing meet the wording of the two element wing.

Credit: Willem Toet

By joining the three element wings cascade element to the flap with twisted vanes, the cross section of the assembly always met the FIA definition of a closed section. Each of the 20 vanes joind the two wing elements such that any cross section always had the upper and lower elements joned by part of a vane. This met the rules, just as the fishbone exhaust outlets in 2009 or the F-duct slots in 2010 met the closed section rule.

This high downforce wing was initially envisaged for a Monaco Debut, but was already prepared before the car was launched. BAR had planned a media launch day at Barcelona, as was often the practice back in those days, the teams reserved the track the day before for a shakedown and filming. Taking this opportunity to test the wing the team ran the 20-3 element design for several laps and then hid it away from the media arriving for the launch the next day. Un be known to the technical team, these laps were photographed and filmed for the teams official website and PR material. At one point it was said this “secret” rear wing was on the front page of the BAR Honda website! Once discovered the public images were removed, but BAR feared the secret was out. The wing was track tested at Silverstone by Anthony Davidson. I was unaware of the wing and only noticed the vanes when reviewing the photographs. Although I recalled that the team were fitting a gurney to the car at the time that had slots cut out. At the time I thought this was to allow the carbon fibre gurney to flex around a curved wing. Then my first inspection of the images made me think that a gurney with 20mm serration was being tested. Only later did I discover the 2-3 element wing was being tested and the reasoning behind it. However BAR feared a protest would be lodged if they raced the wing at Monaco so it never appeared at the principality.

Later in the season BAR innovated again with deep fences being fitted to the rear wing, both these and the 2-3 element wing prompted clarifications from the FIA on variation in aspect ratios of the rear wings cross section. Although not published, these demands probably still stand today.

Credit: Willem Toet

 

Red Bull – Monaco floor analysis

Monaco is a unique venue, not just for the layout of the circuit, but also the pit lane facilities provided to the teams. With no space for a conventional paddock and pit building, the teams park their transporters away from the small pit garages. Thus parts have to be ferried in-between the trucks and the pit, as well as parts being stored in the upper floor of the pit facility. Luckily for F1s technical observers, this presents an opportunity to see parts not normally exhibited in front of fans. Just such an opportunity presented itself to Jean Baptiste (@jeanbaptiste76) who saw Mark Webbers floor being lifted up to the mezzanine, through the crowd he was able to a quick photo of the entire assembly. From a single picture we have been to gather a lot of info on the design of Red Bulls floor. We’ve confirmed where the exhaust blows, how the trailing edge forms a flap and exclusively how the starter motor hole is blown by ducts in the upper floor. There also a wealth of detail not normally visible, although not unique to Red bull, seeing this detail is a rare treat.

Firstly we can see that this is a floor that has been run on the car, evident by the burns and dirt generated to what would otherwise be pristine black and silver floor. I suspect this is a floor assembly used for free practice, as the floor ahead of the rear tyres still sports the tyre temperature sensors. These are not typically run from qualifying onwards.

We can also see that the floor is in one complete piece, which is unusual. Normally the front t-tray splitter section is removable. Perhaps with the front splitter being lighter this season, it no longer formed of a large piece of ballast, making having a one piece floor more convenient. Plus the new more stringent splitter deflection tests are probably easier overcome with a single structural assembly, rather than two assemblies bolted to the car. Plus we can see the front bargeboards are a permanent fitment to the floor, whilst the sidepod fins are unbolted from the floor and remain attached to the sidepod fronts.

Exhaust routing

Silver coating (zircotech) and gold film provide heat shielding

We’ve seen many pictures of the Red bull exhaust system, how it curls down to pass the exhaust along the floor towards the outer 5cm of floor aside the rear tyres. Obviously no exhausts are fitted to the floor, but the general heat protection within the engine bay appears a coating applied to the carbon floor (most likely Zircotech). Additional local heat protection is provided with separate heat shields and gold reflective sheet, under the exhaust area. The exhausts then run out of the engine bay and along the floor. Again reflective coating is used on the bare floor beneath.

The exhausts route along the floor and blow beneath the diffuser

We can then see the exhaust exits to the edge of the tyre decks 9the small section of floor between the tyre and diffuser. This area is extensively cut away and the edge of the floor is a metallic part which curls up to encourage the exhaust to pass beneath the floor and into the diffuser. We have seen from pre-season (https://scarbsf1.wordpress.com/2011/02/02/red-bull-rb7-open-fronted-exhaust-blown-diffuser/) that the exhaust curls up into the outer top half of the diffuser, further proven by the additional heat protective coating applied in this area. Recent pictures of the Ferrari being craned away in Spain, show that Ferrari do not shape the floor to encourage as exhaust flow to pass under the floor, McLaren are also more similar to Ferrari than Red bull in this regard. As of Monaco 2011, Red Bull were the only team to passing the exhaust flow under the outer edges of the floor towards the diffuser.

Trailing edge flap

On the diffusers trailing edge a flap aids downforce

Red Bull switched to a revised diffuser at the Chinese GP, this exploited a new treatment to the top trailing edge of the diffuser. Rather than a simple Gurney, the team formed a flap above the trailing edge in-between the rear wing endplates. This was not a new feature in F1, Toro Rosso launched their car with just such a flap and historically many cars have sported the detached gurneys of flaps. The Arrows cars in the 2000s sported just such devices. Completely legal, these simple aerofoil sections of bodywork, sit within the allowable area for bodywork at the rear of the car. Much like the gurney, these devices aim to use the high pressure air moving over the diffuser to create a low pressure region above the diffuser exit, to drive more flow out of the diffuser beneath. Effectively making the diffusers exit area larger than a simple exit.

Blown starter hole

Two inlets lead to ducts (yellow) that feed the Starter Motor Hole with airflow

What’s most interesting from Jean Baptistes picture are the two ducts set into the floor ahead of the diffuser. Looking closer we can see these two inlets, lead to ducts that pass inside the engine bay and either side of the starter motor tube. The starter motor hole in the boat-tail of the diffuser is a wide slot, so I believe these ducts blow the starter motor slot. Until other teams cottoned on to Newey’s exploitation of the outer 5cm of floor, most teams pointed their exhausts towards the Starter Motor Hole (SMH), as a way of using the high velocity exhaust gas, to drive more flow through the diffuser and thus create lower pressure for more downforce. With Newey’s outer blown diffuser he could not exploit the large SMH with his exhausts, so this solution allows him to exhaust-blow the diffuser and passively-blow the SMH. By passive-blowing, I mean the exhaust is not used to blow the SMH, but simply the normal airflow over the car. Of course the effect of this passive blowing is dependant on the airflow approaching the ducts inlets. The RB7 has all enclosing bodywork around the gearbox and floor. So airflow could not directly lead to the SMH. So Newey has had to duct flow to this area. It’s unlikely that the flow arriving at these ducts is that powerful, having had to pass around the sidepods and over the fairings covering the exhausts. This is likely to be a small aero gain, albeit one that other teams with similar gearbox fairings could employ. Should the engine mapping ban make the outer blown diffuser solution too sensitive to throttle position, then this duct could receive the exhaust flow to still provide a degree of blown diffuser.

Other details

The T-Tray is formed with the floor and has an opening normally covering by the plank

Away from the unique Red Bull features, the floor exhibits a lot of standard practice for contemporary F1 floors. In Red Bulls case the floor completely encloses the underneath of the car, only a small open section in the t-tray splitter is open. This opening will be enclosed when the plank is fitted to the car. There’s probably a matching section of ballast attached under the chassis that fits in the hole, allowing the ballast to sit a precious few millimetres closer the ground.

An older Red Bull floor (this floor can be purchased via F1-247.com)

With other teams more sections of the floor above the plank are open, and in some cases the base of the monocoque also forms the floor, so the removable floor section has even larger openings.

Enclosed Lower Leading: note the ECU inside the hollow section

The area forming the front lower leading edge of the floor also has to house the Side Impact Tubes (SITs). Clearly with a one piece floor like this, the floor cannot be removed with the SITs still attached to the monocoque. Many teams have the SITs removed with the floor, by unbolting them at the side of the monocoque. This would appear to be the case the RB7 floor. Although not visible in this photo, presumably the removed SITs remain with the car, so possibly this floor is being changed, rather than stored temporarily for refitting.

Such is the tight packaging of the area within the sidepods; space for electronic boxes is limited. We can see a small black box and loom within the enclosed section of floor. Just to the rear of this there appears to be a blue-grey square set into the floor. This is probably a transparent window for sensors to project through, most likely the ride height sensors. Normally three are fitted, one to the left one the right and another at the front or rear, these three ride heights can be extrapolated to provide the engineer with the cars attitude to the track.

Note the wiring for sensors passing around the floor

There is also a reasonable amount of wiring loomed around different areas of the floor. When wiring was seen dangling from Vettels front wing mounts earlier this year, people were quick to assume, this related to wing flex. But instead a lot of the car is instrumented, both for data acquisition but also troubleshooting during the race. In the case of the floor, two measurements are commonly taken, pressure and temperature. Pressure sensors log the pressure beneath the floor, should a car suffer damage in the race, the team can tell from the telemetry if a change in pressure readings are likely to cause handling problems. Equally teams have been known to fit temperature sensors the titanium fasteners holding the plank to the chassis. If these skid blocks, ground too frequently they will heat up. This delta in temperature will alert the team that the plank might be suffering undue wear and cause legality problems in scrutineering.

More pictures from @Jeanbaptiste76

http://twitpic.com/57snf2

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