My writing style is simply straight from brain to keyboard. No edits! There's more to come, but I need to spend time analysing the data from Abingdon and Prescott before I write the updates.
The Abingdon CAR-nival is a pretty hectic day for sprinting. Scrutineering, signing on and the drivers' briefing are half a mile from the paddock and there's a convoy run, two practice runs and two timed runs before lunch. After lunch, there's another convoy run, two practice runs and two timed runs on a different course. The day started dry, but it soon turned to rain, which became so bad that they halted the event for 45 minutes as the first corner was barely visible and water was flowing through the paddock. My boots have since fallen apart! A tentative morning after my Crystal Palace crash in the wet left me chasing the class lead, half a second behind, so as it dried out in the afternoon (bright sunshine and bone dry) it was all to play for. A good run put me comfortably in the lead and I was lucky enough to receive my trophy from John Watson!
To understand how I went at Abingdon this year, let's compare with last year. Initially, I made a better start in 2013, but the 2014 gearing was shorter and I was travelling faster within 70 metres of the start. Last year's car ran the low rear wing, whilst I ran with maximum rear wing in 2014 with the wing in its high up position and the flap at maximum angle. The rate of acceleration slowed and 200m into the course at less than 90mph, the 2013 car was going quicker. The 2014 car had pulled just half a tenth in this period of better acceleration. By the time I hopped on the brakes in 2013, I'd gained quarter of a second in just 350 metres.
This is where the time was gained. I was far braver (60 metres braver) on the brakes into the chicane. This gave me an overspeed of some 15mph during the braking zone and netting 1.13 seconds before the apex. A slower exit from a poor line through the right-hand of the chicane led to a speed difference onto the straight, even though much of the speed difference was pulled back by the straight. I presume a wider exit cost time on the final left in 2013 and that allied to the greater downforce and shorter ratios in 2014 closed the gap. The gap in speed carried on all down the straight, costing 0.33 seconds in 2014.
I was again far faster in 2014 on the way into the corner. On this run, I dragged the brakes slightly, scrubbing off 27mph by the apex, but being 9mph faster than 2013 at best. Apex speed was almost identical, but I did have tremendous understeer in 2014 suggesting that the high downforce setting was bringing the centre of pressure too far rearwards. I'll try a lower wing angle at a later date, which will reduce leverage on the front, hopefully giving more overall grip and lower drag. Another run showed a 4mph advantage in apex speed, suggesting I was also off the boil on that run. The later braking gave a tenth.
Helpfully, my data logger made this year's best run a few tenths quicker than last year's. Given that the official timing made last year's a 44.85 and this year's a 44.59, I think we can say that's within tolerance. Sadly, I don't have data from my best run last year, which was a second quicker than the reference lap shown here, but there's enough information here to say that the high downforce configuration is considerably slower as a much better drive resulted in a time just a few tenths quicker. Next year, I shall revert to a lower downforce configuration. It is worth noting that despite a further year of (ab)use on the same tyres, that apex speeds seem remarkably consistent.
Last edited by andylaurence on 23 Jun 2014, 23:24, edited 1 time in total.
After several years of sprinting and spectating at Prescott Hillclimb, I thought it was about time I tried the other side of the fence. I booked the first day of Longton DMC's first event at Prescott. Walking up the hill in the morning, I realised it's quite different from the tarmac versus the lawns. What struck me was the gradient that is not apparent until you walk it. I realise that sounds daft, like saying the most amazing thing about The Leaning Tower of Pisa is how much it leans, but it really is.
I struggled through most of the day to find any time. After taking a trip through the gravel at Pardon on the first run, I knew I needed to be careful with the amount of lock I had. I managed the next 3 runs within just 3 tenths, leaving me to shake the hand of Luke Trotman, with whom I had been battling all day, and congratulate him on his win. Totting up my best sectors of the day put me two-thirds of a second down. Knowing that wheelspin in Pardon was a big problem, I softened my dampers to minimum softness and gave it all on the final run, lopping 1.1 seconds off my best to take the win by 3 tenths. Both Luke and I were quite surprised.
Sadly, I don't have the data from the run, but I do have the camera footage and the split times to thumb through. Off the line, the timing system shows I was 0.45 behind Luke after 64 feet and my final launch was my best by 1/100th of a second. I was 2mph quicker under the bridge and my sector from 64 feet to Ettores was 2 tenths quicker than before and crucially almost a second quicker than Luke. I was over half a second up here and I had been faster all day!
The sector from Ettores to Midway includes Pardon Hairpin, which was where I really struggled. I lost 0.81 to Luke over this section and was now over 3 tenths down but I was 2 tenths quicker than I'd ever been before. Over the final section, I pulled out 0.61 seconds over Luke, beating my previous best by almost half a second. I set all my best sectors in the one run. The video shows I was over a tenth quicker through Orchard, two tenths quicker through Ettores, almost 4 tenths faster through Pardon and the same through Semicircle compared to my previous best.
After breaking the class record several times at Clay Pigeon and still not having my name on it, I was determined to fix it. A slow start in practice put me on a 74.44 coming into the timed runs, which was under the class record, but not under my best time. In the first timed run, I put in a 73.35, followed by a 73.39 and a 72.90. All three were under the class record and the final one half a second off my personal best when the chicane wasn't set out correctly. I was happy with that and even happier that the club gave an extra run afterwards.
It was coming into the second lap of this final run that the moment happened. I turned into the corner and heard a noise as the car spun to a halt. I was bemused, thinking the chain had gone and locked the rear end. It hadn't - the stud in the bottom of the upright keeping the wishbone attached had sheared. The rear wheel was flapping in the wind and there was no lifting equipment for the recovery team. I had to retrieve my trailer and winch it on with the help of all the marshals. Lucky it happened there though, as the consequences of a similar failure at Castle Combe the following weekend would have been severe.
Talking of Combe the following week, it was Sunday evening and scrutineering was at 07:30 on Saturday morning. The stud, naturally, was not available off-the-shelf. Luckily, Grant Motorsport stepped in and manufactured 3 new ones out of EN24 steel and removed the snapped off one from the upright as well as making a new brake line, which was nipped down to the braid. McGill Motorsport supplied some new rod ends for the wishbones (one had broken in sympathy) and it was all finished with 10 hours to spare before scrutineering. All I needed was some sleep!
Having finished the car just a few hours before the event, I wasn't feeling wholly prepared for the Dick Mayo Sprint held by Bristol Motor Club at Castle Combe Circuit. I was wholly prepared though and I rocked up at 07:00 as usual to get scrutineered as early as possible, grab breakfast and make time to chat to all the people I was bound to bump into at my home event. Importantly, I was competing against Andrew, who I'd cajoled into buying a Van Diemen RF01X from Dermot's emporium and this was his first ever sprint. Baptism of fire!
Other notables in the class was Matt Carter, fresh from his 3rd place finish in the run offs of the British Sprint Championship, Clive Wooster (who beat me at Llandow), Luke Trotman (who had forgiven me for taking his pot at Prescott) and Tom Arnold, who hoped his electrical gremlins were finally behind him after replacing ... everything! It was boiling hot and my objectives for the day were to beat my class record and take 2nd place (or nobble Matt's car and take the win). I wasn't feeling nasty, so I chose to aim for 2nd place!
On the first practice run, I needed to test the brakes, so I gave them a good firm press between Folly and Avon Rise to make sure I'd stop going into Quarry. I was back onto the pace by Hammerdown and the second half of the lap went together quite well. Given the brake testing, 4th place wasn't a surprise, but I was incredibly surprised to be within a second of my class record and only a few tenths off Luke in 2nd place. Matt had taken 3 seconds off the class record - foregone conclusion!
The second practice run was my opportunity to put a stamp on the timesheet and I put in a reasonable run that was 1.3 seconds inside my class record. Result! Matt was now 4 seconds under the record, Clive was also a few hundredths inside it and Luke was just 3 hundredths off it. I the day finished like that, I'd be happy, but Clive has a tendency to go faster each run, often by a second.
My afternoon started with the first timed run being a solitary hundredth quicker than my practice run. Unexpectedly, everyone else went slower, probably as a result of the heat cooking the tyres. Even Clive! That was one objective complete - I'd shattered my class record, even if Matt had obliterated it. Git! The second timed run was all or nothing and I went 2 hundredths slower, probably as a result of a little oversteer on the exit of Quarry. I'd like to say I was perfectly consistent, but I think the track conditions worsened at the same rate I improved. It was a good result though as the video shows the start line was a few feet further back and Castle Combe had decided to put tyres on the apexes for some reason, so the lines were a little more wiggly than normal!
There's been a lot of "I think" and "probably" here without a lot of evidence. There's a good reason for that. I've pulled out the Race Capture Pro as it's being replaced by a Xoombox from Xoomspeed. That neatly coincided with the little read-only tab on the SD card in the RacePak falling off, so it couldn't write to the memory card. The Xoombox will provide some solid data (whilst interfacing perfectly with Xoomcentre, which I've been using for a while as an analysis tool) as well as giving the possibility of adding launch control, traction control, flat-shifting, down-shift blipping, and even full pneumatic shifting. I've been collecting components from Chinese sellers with mixed success to build a dash (sequential shift lights and gear indicator) and pneumatic control system.
The closest I have to data at Combe is to compare video with my 2013 times, but not the class record as the video failed last year. I've split the track into several sections to compare the times. The first thing to note is that my 64 foot times were a few thousandths quicker, most likely reflecting the track temperature. By the end of the pit lane, I was 0.18 ahead this year, most likely for the same reason. I lost 0.12 through Folly, which suggests the car is accelerating less quickly. This isn't surprising as I was running the wing in its high position with the flap backed right off. It's more drag than the low drag configuration, but it doesn't correlate with the rest of the lap, perhaps because of alternate gear ratios and the other aero changes made over the winter. I was quicker from there to Avon Rise, probably through more commitment over the Rise. Maybe I wasn't flat last year or my line was different to account for the lower grip.
A few more hundredths through Quarry brought me back to a 0.15 advantage over 2013. I gained time to The Esses, suggesting a quicker exit speed from Quarry, which is what I felt at the time. Significant time was gained in The Esses, which is strange as I felt there was more to come and I thought I had always been fast there. Despite that, I seemed to have found nearly half a second and a few more hundredths through Old Paddock. I also gained significantly through Hammerdown, which suggests that either the ratios/aero changes have improved performance at these speeds or the extra speed carried through Old Paddock multiplied the gain on the run to Tower.
Significant time was made through Tower, which I know is my nemesis. I also managed a few tenths through Bobbies to finish 3 seconds ahead of my first timed run in 2013. The comparison is shown in the graph below.
Before finishing this write-up, I should point out Chris Buckley's performance. He'd never driven a sports racer, a car with slicks or an aero car and he turned up in his newly purchased Radical SR8. He knocked 15 seconds off his first practice time to finish barely a tenth behind me and set a new >1800cc class record. We've agreed to double drive our cars for the last two events, so he'll be aiming for my class record in the ADR at Clay Pigeon, whilst I aim for FTD in his SR8 at Combe in October...
After a break in August and September, it was back to Clay Pigeon for the third time this year. I was feeling a bit under the weather, but resolved to give it my best shot. Since the Dick Mayo Sprint in July, there had been a few changes to the ADR. I'd started work fitting the Xoombox with the LEDs fitted to the dash, gear position, RPM and wheel speed hooked up.
After the battering the nose took at Crystal Palace, I also asked Dynamic Mouldings to fix the broken front clam, take out the lighting pods and close up the front vents. They did a cracking job and the new nose looks fantastic.
Anyway, back to Clay Pigeon and the sprint. I was struggling with a lack of grip, most probably down to the temperature and lack of rubber on the tyres. I think I'll need a new set for next season (these have done 3 seasons) and I was barely under 80 seconds. The corner through the finish is normally flat out but I didn't manage that this time, putting two wheels on the grass on the exit and scaring myself a little, barely stopping for the chicane!
A spin on the first run led to a rather tardy 83 second run and a nice smoky spin turn to return to the right direction. I was still leading the class despite this. I put down a benchmark in the second run of a 76, which was pretty poor. I had another spin on my final run and decided to call it a day, trundling back to the paddock. I received a class win and a car that wasn't damaged, so that was good news! Team Bristol Motor Club had 4 entries on the day, picking up two wins, a second place and a PB. I had the pleasure of driving Phil's MX5 home too, which was a change to towing the ADR.
After Clay Pigeon, I managed to score a double drive in a friend's Radical SR8 for the Pegasus Sprint in October. It was cold and wet at the start of the day, but dried out for the timed runs, which was handy as we had no wets. We had a close battle all day and whilst Chris had the lowest average time of the day between us, I managed the fastest time of the day and thanks to no single seaters at this event, I scored my first FTD!
A week later, I was back at Castle Combe for Supercar Saturday to give rides to people who were kind enough to donate to the Stroke Association. A £40 donation got them 5 laps around Castle Combe in 350 seconds overtaking traditional supercars like Ferraris, Porsches and Nissan GTRs. Most were surprised at the difference in performance between a road car and a racing car, myself included. It's not until you share the track with a road car that you realise just how fast a proper racing car is. To exit the pits as a car flashes past on a flying lap only to overtake it on the exit of Quarry really brings it home.
A flying lap showed that the gearing was too short with the limiter in 6th being hit before Folly. An extra tooth on the front sprocket for the Great Western Sprint, I think! I did more laps in one day than I had done through 2013 and 2014 to that point. Despite running around at 90% (it's demo laps afterall), I picked up some knowledge by playing around with lines and gears. I also gained confidence at Tower and Camp. The extra weight of a passenger brought the car closer to the ground and the sustained high speed led to much higher downforce than usual. This snapped the four aluminium braces for the splitter and tore the crash box apart.
Hasty repairs with new bolts, rivets and some aluminium got me back on track, but it didn't last and the whole splitter wore to nothing, grinding the skid plates off, the heads of the bolts holding the mounts in place and then wearing through the splitter itself. Game over!
At this point, it's lucky that the winter break is here. It's also lucky that I've been thinking about re-designing the splitter into a proper front diffuser instead of the cobbled effort of last winter. Here's the first sketch to be tidied up before some CFD development....
