Dual Plane Wing

This weekend, I spent some time fitting a flap after the main plane of the rear wing and some new end-plates to facilitate this.  I used the old end-plates as templates and drilled a couple of holes to fit the main plane.  Once the end-plates were fitted, I used a flat-bladed screwdriver to remove the foam core around the edges.  Some black epoxy filler sealed the gap and after 24 hours to cure, a quick once over with a sanding attachment in the Dremel made them good enough.  If I was fussy, I'd make it a bit neater and use a polishing bit too, but I compete against the clock, not the flannel!

End-plate foam removed and sealed

In the absence of any data to decide where to mount the flap in relation to the main plane, I took an educated guess with a 6mm slot.  Marking in the right place, I clamped both end plates together with the holes for mounting the main plane to ensure the flap was mounted symmetrically and drilled a hole.  After mounting the end-plates back on the main plane, I bolted in the flap.  Using the angle brackets that previously mounted the flap, I relocated them to fit the slightly wider main plane and angled the flap to the same angle as the trailing edge of the main plane.  Dremel to the rescue and I drilled the second locating hole.  Wing fitted!

Rear wing fitted

Admittedly, there's a few issues to be sorted out.  The flap is narrower than the main plane, so there's a 12mm gap between the end-plate and the flap at each end.  Also, the flap is flexing and I think it's safe to say it's flexible enough that it will close the slot gap between the two at speed.  A couple of supports along its length should solve that minor problem.

Of course, I've no idea of its performance, so the next task is to fit the spare camera to the rear wing support and tuft-test the underside to ensure the flow remains attached in normal conditions.  The data from the next event will show whether it's producing more downforce and more drag.  I'm hoping for lots of the former and very little of the latter!

Bike vs Car

The debate has raged on for years.  It’s like a religious war.  Cars can ultimately be faster, but bikes can come from a showroom with a tax disc for the price of a hatchback that will out-perform anything on four wheels you can buy for 5 numbers and the bonus ball.  Even Top Gear have compared the two.  So, what better time to dig up old ground than TT week and what better course to compare the two on than the Isle of Man TT course?

The challenge is to estimate the performance of my bike-engined car and compare it to the performance of the bike.  The ADR seems the ideal vehicle of comparison as it uses a production 1000cc bike engine fitted into a spaceframe chassis, clothed in composite bodywork.  It also takes two people, but not in this test!  The first thing to note is that the ADR has a top speed of around 130mph with the GSXR-1000 bike engine fitted, so we’re never going to beat John McGuinness in the ADR.  The outright lap record for a car is 19:37.4 by Mark Higgins in a pretty standard Subaru Impreza WRX STI.  The problem here is that this record equates to 115.3mph average lap speed!  Clearly, the ADR is going to struggle to match these speeds.

By the same token, the sidecar record is 116.7mph, which was set by Nick Crowe and Dan Sayle on a 600cc outfit.  The only slower records are that of the 125cc bikes at 110.52mph and the Zero TT electric record of 104mph.  Even the Superstock record is now over 130mph, thanks to the amazing year Ian Hutchinson had in 2010.

So, now we’ve set a few targets, how do we try and beat them?  I don’t have the skills or the balls to take on the TT course and it’s unlikely that the organisers would let me have a go if I did, so the only way to find out is from my desk at home.  For this task, I need some data from the course and a decent model of my ADR to plumb into a simulation tool.  I’m using the free version of LapSim 2009 for simulation and thanks to quite a lot of past effort, I have a pretty good model of the ADR that’s representative of the actual pace of the car.

Race Technology have been kind enough to offer sample data on their website, which includes a lap of the TT course.  I opened that data in their software and exported it to CSV.  As the data was logged on a bike, it doesn’t have the right lateral G figures, but the Race Technology software generates corner radius, so some simple maths generated lateral G from the speed and corner radius.  With this now corrected, I imported the data into LapSim and generated a circuit.  A few minutes later, LapSim had generated a simulated lap for the ADR.

With the data to hand, let’s walk through the lap and see how the Superbike and ADR compare.  The lap for the Superbike is around 19:30, so it’s not a record-breaking lap, but fast all the same.  So, off the line and the superbike reaches 236kph (147mph) before slowing down to 206kph (129mph) at Bray Hill.  The ADR is still accelerating, having started a flying lap compared to the standing start of the bike and takes Bray Hill completely flat at 205kph (128mph), just 0.45 ahead of the bike, despite the flying start.

On the way down to Quarter Bridge, the bike is up to 248kph (155mph), whilst the ADR is still flat out at 206kph (129mph).  The ADR is much later on the brakes, pulling back all that time lost on the straight to round Quarter Bridge 0.62 ahead.  The ADR briefly snatches 5th at around 190kph (119mph) before Union Mills compared to around 230kph (144mph) on the bike, yet the later braking and higher apex speed mean the ADR pulls over 2 seconds lead by the apex.

From here on, it’s flat in 6th at 210kph (131mph) all the way down to Balleraine in the ADR whilst the bike is peaking at over 280kph (175mph) and slowing for all the corners.  Initially, the high speeds see the bike recovering those 2 seconds and making a further 10 seconds, but the slower corners for the bike that the ADR takes flat see the gap down to 8.35 at Balleraine.  The section to Glen Helen is ADR territory and just a couple of tenths separate the two on the apex, the ADR snatching a brief lead before the exit of the corner, before relinquishing it on the straight.  Again, there’s no match for top speed and the bike shoots up to almost 270kph (169mph), accelerating and decelerating for the corners leading to Kirk Michael, whilst the ADR is flat in top, losing 5.58 seconds in the process.

It’s flat out again up to Quarry Bends and the half way point in the lap.  The gap is pretty stable at 5.34 seconds and the ADR is still flat in 6th.  Onwards through Selby Bridge and Parliament Square, it’s the same story of the hare and the tortoise and coming into Ramsey, it’s still about 5.5 seconds that separates the two, the bike still ahead.  The tight section through Ramsey works in the ADR’s favour though and it pulls back the gap to 1.27 seconds by the hairpin and finally makes the pass at the Waterworks to take the lead.  By the Gooseneck, the ADR is 3.4 seconds in the lead, the corners being just right to take advantage of the aero and pull out a lead.

It’s short-lived though, as the bike spears past on the Mountain Mile at 270kph (169mph), opening out a 3 second lead on that straight alone.  By Windy Corner though, the ADR’s pulled it back, the high speeds generating huge amounts of downforce through the corners and it’s 3.6 seconds clear.

A couple of short straights is all the bike needs to buzz past at over 260kph (162mph) on the run out of Creg Ny Baa and that means it’s close on the run down to the finish.  In fact, they’re side-by side at Signpost, but the ADR’s pulled out 5 seconds by Governor’s Bridge and there, on the exit of the final corner is where we’ll leave it as the bike slowed to enter the pits.  The gap?  6.9 seconds.  The average speed for the ADR?  117.827mph.  Faster than the outright car record, faster than the Sidecar lap record and faster than the fastest lady.

Or is it?  You see, there are a few assumptions here.  Firstly, that the car can straight-line the corners like a bike.  Secondly, that the grip is representative of what I’ve seen before in the ADR.  Thirdly, that the car can be driven to its maximum over 60km.  The first assumption sounds impossible, but is actually pretty good.  The bikes lean during turns, so they’re not that narrow as they look on the straights or in the pits.  Also, this doesn’t matter so much on the wide (compared to a single lane track as seen on hillclimbs) roads.  The grip is a total unknown, but it’s unlikely to be that far out.  The third assumption means that it’d take a prodigious talent and balls that’d need their own seat belts to take Higgins’ record in the ADR.

What this does highlight is the amazing talent of car and driver to achieve what Higgins did in a production car on road tyres.  It also highlights just how great these riders are to go two minutes faster around the track than this virtual lap, which was pretty easy from my desk!

Sensibility aside, just what would it take to beat the superbikes?  Let’s stick a Powertec-tuned ‘Busa lump in the ADR and see what we can do.  We’re up to 126.778mph and taken Bruce Anstey’s Supersport record with it, but we’re buzzing off the limiter in top gear for almost half the lap, so we’ll add a tooth to the front sprocket.  The extra 13kph (8mph) at top speed (now 236kph/148mph) is enough to lop almost 30 seconds off the lap time and many of those corners that were previously flat out now need a lift or even a dab of brake.  Bray Hill is still flat in 6th though and that’s 233kph (146mph).  Most importantly, we’re through the 130mph barrier at 130.336, just a whisker off Ian Hutchinson’s Superstock record.

Now I’ve really got the thirst for the outright record, so it’s off to Holeshot Racing for a 350bhp turbo kit and another two teeth on the front sprocket.  That’s done it!  Not only has it broken the outright record, but the 17 minute barrier, the 140mph barrier and the 16 minute barrier!  141.578mph is the result, although the bike is still faster in a straight line.  Bray Hill is still flat in 6th, but this time it’s taken at 261kph (163mph)!  Top speed is now 264kph (165mph) and still held for a large portion of the circuit.

If anyone has rFactor and fancies trying to match this time in their own home with a steering wheel and a computer, please get in touch for some data to simulate the course and the car.  I’d certainly like to see the video…

New Wheels and Surplus Tyres

Tonight, I picked up a nice set of magnesium OZ rims for my wets.  Sadly, the rims are a bit wide for my wets, so I need a new set of wets around 250/570R13 at the rear and 200/550R13 at the front.  I've also got the following surplus to requirements:

2x 180/550R13 Avons of unknown age and compound
2x 250/570R13 Avons of unknown age and compound
2x 180/515-13 Yokohama sticky hillclimb slicks with little use
2x 200/550-13 Yokohama sticky hillclimb slicks bought new last summer
1x 200/550-13 Yokohama sticky hillclimb slick orphaned by a punctured mate last summer
2x 160/530R13 Avon hillclimb wets that look new but have been used at least once
2x 180/565R13 Avon hillclimb wets that look new but have been used at least once

7x 3 piece 13" split rims with a 16x250mm PCD, comprising:
2x 7" width
2x 7.5" width
2x 8" width
2x 9" width (one with centre)

Use the contact form or call 0782 595 3858.

Hub and Aero Upgrades

Since the broken wheel at Castle Combe, there's been a few updates.  I had the option of finding a new set of wheels or replacing the centres (all four to match).  The 4" PCD of the ADR Sport 2 isn't such a popular size and the chances of finding a suitable replacement set in time for the next round of the ASWMC Sprint Championship were small.  Replacement centres would have to be custom made with a lead time of more than a month.  Adrian at ADR suggested a third option to upgrade all four corners of the car to ADR3 spec, which allows fitment of Dallara F3 wheels, which are more readily available.  This gives improved braking, lighter hubs and lighter wheels.  Most importantly, the parts were all in stock and I could be ready for Clay Pigeon.

I got to work pulling all four corners off the car and carting them down to ADR in Holyport.  It wasn't until the rear hubs were separated from the uprights that we realised the ADR3 hubs wouldn't fit my uprights, which are bespoke like most other items rearwards of the driver in order to convert the car from the original live axle to a chain driven double-wishbone arrangement.  By this time, the front was already upgraded and the best way forwards was to get a new bespoke pair of hubs sorted at the rear.  Luckily, everything at ADR is designed in CAD and a few keystrokes later, a new design was sent out for machining.

Sadly, there wasn't enough time for the new hubs to be made before the next event and they arrived a couple of days after the event.  In the meantime, I got to work on other matters.  I took the front of the sidepods off to allow air to escape from the front wheelarch, relieving high pressure and reducing lift.  As a plus point, it also removed 2kg of fibreglass.

Whilst in the garage, I spied my spare rear wing, which is a dual element design.  Having recently purchased some new larger end plates, this seemed the obvious chance to upgrade.  I used Foilsim 3 to estimate the performance of the wings, which suggested 152lbs of downforce at 10 degrees around Camp corner for the main plane.  Now I need to establish just where the flap needs to be mounted and at what angle to achieve similar drag and, hopefully, better downforce.  CFD Gurus, please apply here!

With all that analysis to be done, I took the car down to ADR so that the new uprights could be fitted.  At the same time, I had all the rod ends and bearings in the suspension replaced as after 8 years, I've no idea of their history.  The corner weights and the alignment had to be reset at the same time.  The car now has ADR3 lightweight hubs, new discs, new calipers, new rod ends and bearings throughout, new magnesium OZ wheels and, because the new wheels are wider, a new set of tyres.  If I don't see a step in performance, I'll be disappointed!

Mallory Park Data Debug

Mallory Park was the scene for the first event of the season and the first time behind the wheel for about 9 months.  What does the data say about how I got on?  Starting at the beginning of the data, I’ve plotted RPM for second practice and both timed runs against distance.  You can see that I tried 3 different launch strategies in the three runs, but they all worked out the same by the time I’d covered the first 20 metres.  What this also shows is that by the time I’m doing 32mph, acceleration is governed by power rather than grip.

 RPM from the start line

The second thing of note is that there’s a spike in the revs at about 28 metres into the run on all three runs, as shown by the cross on the vertical marker.  This means there’s a slip between the engine and the road, so it’s either wheelspin or clutch slip.  That could be a bump in the road or a torque spike at that point in the rev range.  The spike doesn’t happen at the same point in the other gears, so that suggests it’s not clutch slip.  It does, however, happen at the same point in first gear after the spin in second practice, suggesting that the tyres are breaking traction as the engine comes on cam.

Moving up towards second gear, the next thing of note is the point at which I changed gear for the first time.  Interestingly, it got progressively further up the rev range as the day progressed and the end result was marginal at best.

The entry into the first corner was tentative in my first run, so in the second practice run, I decided to enter it flat.  I was pleased to see that it was flat in third gear, but less pleased to see the chicane appear as quickly as it did.  You can see that in the second screenshot, where I’ve removed the first timed run.  The blue lines show second practice (top) and normalised RPM (bottom), whilst the red lines show the same traces for the second timed run.  The normalised RPM channels are simply RPM divided by the ratio for that gear.  These traces are directly comparable from the first vertical dotted line to the solid vertical line.

Turn 1 RPM

In second practice, the revs continue to climb (top blue line) in 3rd gear all the way through the corner and speed continues to climb as a result.  The next thing to note is that the red traces dip at 317 metres into the run, showing I’m on the brakes for the chicane.  At this same point, the blue traces show I was going 5mph quicker in second practice and the dip in the blue lines showing braking start at 341 metres and going 7mph faster than the other trace showed 24 metres earlier, which is probably why I arrived at the chicane backwards.  Clearly, I learned too much from that spin and was far too tentative in the afternoon as braking 24 metres later was clearly the problem, rather than the extra speed.

So, how smooth is my driving?  Looking at the acceleration data, we can get an idea.  The image shows the acceleration off the line at the bottom, moving about a bit and a small amount of yaw when the line moves to the right.  A single line connects the acceleration zone to the cornering zone on the left.  The line moves about quite a lot on the left side of the graph, suggesting noise, a lot of bumps or a lack of smoothness from the driver.  Most likely, a combination of all three.  Intriguingly, we know that speed didn’t really vary on this, the final run throughout the corner, so the acceleration G being consistently positive doesn’t stack up.  There’s several possibilities; the sensor is mis-calibrated, the acceleration through the corner is making the rear end squat under acceleration and tilting the sensor or the car is oversteering slightly throughout the corner and the acceleration shown is actually a component of the lateral G.

Turn 1 acceleration

Acceleration data can be viewed in other ways too.  Look at this graph showing the longitudinal acceleration stacked on top of the lateral acceleration.  The data is normalised so that acceleration is positive for all directions.  You can instantly see that the highest points on the graph are when braking into a corner, turning into the first chicane (around sample 300) and also into the hairpin (around sample 950).  You can also see that I completed my braking before turning into the second chicane (around sample 600) by the trough in the graph.  This shows I braked too early and coasted into the corner, not utilising all of the grip available from the tyres.  Tenths to be gained there and also at the similar point in the final chicane (around sample 1040), which I entered with just a lift of the throttle and again on the change of direction in the chicane.

Acceleration stacked

Additional information