June 2018
29Jun
Pneumatic check
I managed half an hour in the garage on Friday evening, and checked the hoses and air pressure to see if I could find if there were any signs that may explain the gear selection issues. With the actuator disconnected from the gearbox, I noticed that there didn't appear to be much pressure when I pulled the paddles. So I disconnected the hose between the regulator and the solenoid block, and fitted a pressure gauge, and I could see that the pressure was only 4bar, or about 70psi. When the solenoids fired, the pressure dropped to almost zero, and then climbed rapidly back to 4bar. That didn't look right. The pressure in the paint ball bottle was below optimum, at around 2000psi, so I refilled it from the dive tank, but the pressure to the solenoid block was still only 4bar. So I adjusted the regulator, to bring the pressure up to 7bar (100psi) and then when I pulled the paddles the solenoids reacted far quicker. So I think the gear change issues at Snetterton were simply down to lack of air pressure. I'll leave the gauge plumbed in to the air feed, so I can keep a closer eye on the pressure from now on.I've got another set of Force Racing wheels on order, these will be used with a set of new A15 tyres, and will be saved for timed runs and run-offs. I'll have them in time for Lydden Hill on July 14th. I am booked in at **** before Lydden for some upgrades, to check the gear change system out, and to have the car corner weighted again with the replacement push-rods fitted all-round.
27Jun
Gear change issues
Since the car was setup for launch control in 2017, it nearly always makes a very unsatisfying lurch in first gear, where the car accelerates at full power, then the power is reduced, and the car then accelerates again in first gear, until second gear is selected, and the car then continues to accelerate like a rocket. I've had a few launches where there is a real kick in the back, where it doesn't lurch, and selects 2nd gear sooner and really does go off like a scalded cat. Following the issue on Sunday where the gearbox ended up in between 1st and 2nd gear, with no drive to the wheels, I have looked at the data, then compared it with older data, and I've realised now that the lurch in 1st gear, is in fact the ECU trying to change gear, but it nearly always is unsuccessful. If you look at the gearCutState and the gearVoltage, it can be seen that the ECU has tried to select 2nd gear, the gearVoltage rises as the actuator tries to get 2nd gear, but for one reason or another, it fails to get 2nd, and the engine power is then cut and the ECU tries again about a second later.What makes if difficult for the ECU, is that the rear wheels are spinning during the launch, and there is a lot of inertia involved, and torque, and getting 2nd gear isnt always physically possible. I'd like to think we can cure this with some tweaks. On the two run off runs on Sunday afternoon, both times, 2nd gear went in when the ECU first fired the actuator, and both launches were unbelievably quick. I'm going to see if this can be cured, by ****, with a few minor tweaks to the map.
Looking at the gearCutState channel, and you can see it says "YES", and directly below the gearVoltage does rise, but as the change is deemed unsuccessful, the gearbox stays in 1st gear, and the revs drop, as the wheelspin recedes, and the car tries the 2nd gear again, but this time it is successful.
The other issue I had on the first run off on Sunday, was getting stuck in 5th gear. The screen-shot below shows the three attempts to change down from 5th, but the gearbox doesnt cooperate. This is also software related, and again, I need to see if **** can dial this behaviour out. It cost me at least 2 seconds on my finishing time, if not more.
On the Practice run when the gearbox seemed to go in to neutral instead of 2nd, its a similar effect to the first one above, where the ECU fails to get 2nd gear during the launch, and the gearVoltage is actually neither 1st gear (1.5V) nor 2nd (2.1V), but the selector is halfway between the two gears (1.8V). This time however, we have what I'm told is dog-on-dog, again, a software issue, and the ECU shouldn't have allowed the power to be applied with the gearbox not having completed a full gear change. Mark Bailey says the box should be OK, and it is 100% a software issue.
25Jun
Snetterton points scored
A good result on Sunday at the BSC Round 6, with a 9th place in the Top 12 Run Offs and a healthy 6 points scored. I wasn't as fast as my first timed run before lunch, where I set a new PB of 83.51s, knocking 2.86s off my PB set the year before, but I had a few gremlins with gear-changes which were hampering my progress.On Saturday I started off far with too much caution, on the new push-rods, and my first practice run I was 5s off my PB. I gradually improved, but as I'd started so slowly, my final timed run of the day was simply too slow to qualify for the Top 12, so thats going to have to be a score I will drop at the end of the season.
The engine was also running very hot during the two days, with ambient temperatures around 28C, little wonder the radiator fan wasn't capable of cooling the engine down after returning from a run. The air charge temperature reached a whopping 50C on my final run off run on Sunday, but the car was still flying, and the new suspension push-rods worked perfectly. Stewart Robb (Pilbeam V10) took FTD on Saturday, with Colin Calder repaying the favour on Sunday. I am now 12th in the BSC (dropped two places) but its still a long way to go, and I need to keep driving fast and scoring points to be in with a chance of a Top 12 position.
I've ruined the front tyres, trying to carry speed around Palmers, mind you they've done 44 runs since I bought them in March, but thats too many runs to hope to keep them competitive when racing against people who keep turning up with brand new tyres. I'll replace the fronts, but the rears are going to have to do a few more events before they get changed.
20Jun
Uprated push-rods
I collected the uprated 22.22mm CDS push-rods last night, and set about fitting them to the rear suspension, which is not as straight forward as it may sound. Having paid TripleM to have the geometry setup, the length of the push-rods is critical as they dictate the car's ride height and weight distribution. Basically, the new push rods had to match the exact length of the OEM ones, or the car wouldn't handle properly, but as I'd bent the near side OEM push-rod, that was easier said than done.I started off by removing the unbroken left hand push rod, and by comparing the two push-rods side by side, I built the replacement push-rod up to as near the same length as the OEM rod as I could. Using brand new (and very expensive) aurora push-rods, I wasn't taking any more chances with breakages. Once the left hand uprated push-rod was refitted, I then dismantled the OEM push-rod to remove the turnbuckle, and then I could build up the uprated right hand push-rod. Not as easy to do as the left hand, because the bend in the OEM push-rod affected its overall length. I measured the centres of the rod ends at ~645mm and did my best to build the replacement up. I then fitted it back on car, and marked the nuts with yellow acrylic paint.
I'm not disturbing the front OEM push-rods until after Snetterton, as the rear geometry is already less than optimal following the accident, and I need to get the car back over to Triple M in July for a proper setup session. So I'll leave the front end as is, and see how the car handles with the stiffer push-rods. A very big thank-you to Altiss Engineering again, for the rapid turnaround and excellent workmanship.
I ran the engine, for a few minutes, on the new throttle body, and it started ok, with no lumpy tick-over. I'm not saying I've cured the problem, it may not be the same conditions for one, so I'll see how it goes over the next few events. The car is now back on the ground, and after I cleaned the tyres last night, there are just a few jobs left to do prior to heading over to Snetterton on Friday afternoon to get setup.
Watching the on-board video from Snetterton last year, where I am just cruising around some of the corners, I am hoping again to better my PB, and qualify for both Top 12 run-offs of course. The DJ wings made a 6.56s difference at Pembrey, so lets aim for similar improvements at Snetterton. My PB at Snetterton 2017 is 86.35s, and I reckon I can shave 4 seconds off. However, to challenge the shared SBD Dallara and Steve Miles in the Van Diemen, I need to do a sub 82 second run, so if I can improve by 4 seconds, I'll be extremely happy :D
19Jun
Social stuff
The Instagram feed is going quite well, with over 430 followers, and the facebook page is also nearing 950 followers. I do work hard to provide fresh and I hope interesting material, so please head over and take a look at the content, and like it to ensure you follow the latest posts.
18Jun
Snetterton Finals
I am running #15 at the weekend, with just 19 BSC drivers present, which is 6 fewer than we had at Pembrey. In total there are only 89 cars entered, which doesnt sound a lot, but there were 90 entries at Castle Combe in comparison, so its not a bad turnout. Its just a shame the sprint is only using the inner 100 circuit, I can only guess that using the full 300 circuit would have meant much higher entry fees, but then, if Javelin can afford to book the whole track, why cant we?15Jun
Throttle body swap
The advice I was given was that the engine was hunting at tick-over due to a faulty throttle body, with Pete and another Mygale EcoBoost owner suffering the same symptoms, which they cured by swapping the unit out. Luckily yesterday I found a seller on Ebay with some new OEM TB's, so I ordered one and it arrived today, and is now fitted to the car. I shall see over the next few days if the problem has gone away. But seeing as it was intermittent, it might take longer to prove that I've resolved the issue. The retail price should be £270.14+VAT so it was a bargain indeed.14Jun
Diffuser is repaired
I have further reinforced the diffuser floor with some strips of carbon cloth, and I've drilled the 40mm² titanium blocks and countersunk them so they will sit flush with the surface of the plank. I'll also Sikaflex them both to the floor, so even if the bolt heads do eventually wear away, they hopefully wont fall off. I'll reassemble everything tomorrow evening and get the diffuser fitted back on to the car.On Saturday, when I started the engine from cold, it hunted, rather than settling in to the usual 1500rpm cold start rpm that then gradually drops until the water temperature has risen. It sounds like its going to stall, and then the ECU opens the throttle and then the stall sounds imminent again, and so on. I'm not sure if its a problem with the throttle servo, or an air leak. The next time it does it, I'll attach the laptop and check for errors, and download the logs to see whats going on. It also did this at Pembrey on the Saturday morning, again from cold. Thats twice in two events, I hope its not an issue with the engine.
13Jun
Euler's Buckling Load Calculations
The diffuser is off, and is looking not too bad considering the abuse it's had since the grounding out at Castle Combe in March. The 5mm plywood plank is pretty much worn away to zero, so I've replaced it with a thicker 8mm sheet, with new titanium blocks. I'll also be sticking Tufnol strips to the underside of the diffuser, to protect it in some of the more vulnerable areas. I've also thoroughly checked the suspension, all round, and I can see no issues. The Aurora rod-end on the pushrod that snapped, shall be replaced, and I shall be using new left and right hand rod ends on all of the uprated pushrods when they are made.I have reported the event on Saturday to the event organisers, and they are investigating the surface where I bottomed out. I felt it was the right thing to do. They should at least warn drivers at the drivers briefing about the change in surface, to prevent anyone else from suffering the same fate. I have provided front and rear facing video, and telemetry, as evidence.
The Euler Critical Buckling Load formula I used to calculate the strength of the 22.22mm OD push-rods has been checked by Prof. Ray Lohr, and the calculations I made are correct. Also Roy Simms, whose Ralt uses the same specification tubes, has confirmed that they do bend in an accident, so I'm now very confident that they will do the job.
The calculations for the replacement push-rods made from CDS are as follows:
Buckling Load = π²EI (KL)² E = Youngs Modulus of Elasticity (stiffness) for cold drawn steel, is 200 GPa or 200,000 Nmm L = 600mm (Length of the pushrod tube) K = 1 = both ends pinned (hinged, free to rotate) I = Moment of inertia = (π / 64) * (D^4 - d^4) D = 22.22mm (Outside Diameter) and d = 18.16mm (Inside Diameter based on 2.03mm wall thickness) ∴ I = (π / 64) * (22.22^4 - 18.16^4) = 6627 So putting those figures in to the formula for Buckling Load gives the following: Buckling Load = (π² . 200000 . 6627) / 360000 = 36,337 Newtons (3,705Kg)If we were to reduce the wall thickness to say, 1mm, the buckling load formula gives 20,620N or 2,103Kg. If were then to reduce the OD from 22.22 to say 19mm, then buckling load with a 1mm wall thickness is 12,597N or 1,285Kg! The question is, what load should we account for? And what tolerance do we factor in?
Note from Prof. Lohr:
I have assumed that they are perfectly straight tubes, with perfectly axi-symmetric loading and frictionless pin joints (rod ends). In practice those conditions wont be fully realised resulting in some bending which will lower the critical buckling forces.The formula for Euler's Buckling Load is from the book, Fundamentals of Machine Design, vol 2, page 617
And finally... I made the front cover of speedscene magazine this month. Steve Kilvington took the picture, I'm not sure its the best 'image' I have of the car, the down force was pushing the floor in to the ground, hence the trail of sparks, so it actually shows the inadequacy of the springs and rear suspension, rather than a well setup car 'sparking'. Still, its a privilege to make the cover, and I'll keep it safe to show the grandkids one day :D
12Jun
Data logger results
The Pi Datalogger was running at the time of the accident, however, in the code I've written the Pi saves data to the SD Card whilst the car is moving, and closes the open file when the car comes to a complete stop. For some reason, I don't have any data for that run, I cant think why, it's disappointing too as it would have shown the demise of the push-rod prior to the corner where it failed. But if we discount the missing final run, I can actually see a difference in the resting value of the corner that failed, on the data captured on the second practice and first timed runs, which suggests that the arm was bent by the impact during first practice, but we just didn't notice it. The thing is, you cant check everything between every run, there's just not enough time. But wouldn't it be beneficial if the data logger could warn you about something that is 'out of bounds'. ie the voltage from one sensor was different to the voltages seen from previous runs, I'm sure we could build something in that gave the driver a bit of information to warn of a possible impending failure.Anyway, this is the graph showing the deflection in the rear suspension, caused by the car crashing down through the undulation on the Abingdon course. If you look at the two red lines, these show the voltages rising as the down force increases with speed, caused by the dampers becoming compressed as the rear of the car is pressed downwards. At around 120MPH I hit the depression in the circuit, and the suspension fully compresses, sending the red lines to the top of the graph, the suspension then recoils as the 1150lb springs force the rear of the car upwards, the suspension then bounces back up to maximum, before finally settling back to before the impact, and as the car continues to accelerate the down force continues again to build.
I have a selection of spare parts from Radical and Jamun racing, and I had hoped I had some rear push-rods in my collection. But, I dont. I have four shorter front push rods, and some even shorter push-rods that I cant identify. And I discover that my car is also using rear push-rods on the front suspension, which means the four front push-rods in my spares bin are completely useless. Anyway, I'm getting some new ones made, which wont break. And then someone mentioned something called the Euler Buckling Load calculation, which is a formula used to determine the force required to buckle a shaft or tube. The idea is that the material selected for the push-rod, provides just a little more strength than what is needed to prevent the tube from collapsing, but, the idea is that in a crash, the tube would still buckle to save any more damage to the chassis/gearbox than is necessary. If I over spec the replacement push-rods, and go in to a barrier sideways, they may not buckle, and instead, the chassis or gearbox gets damaged. I've done the maths on the 22.22mm od 2.03mm wall thickness 600mm long push-rods, and I make it around 36000N or 3600kg, which sounds a bit high. That could be my maths of course. Let me know if you understand the Euler calculations, and maybe send me what you think is the right dimensions for the replacement push-rods.
11Jun
Spinning around
I'm going to dwell on the positives from Abingdon, and not what could have happened. It was a very well run event, and the 7 runs I completed were all important seat time, where I was getting more experience behind the wheel, understanding how the downforce has improved the performance. On the first practice run on the afternoon's Abingdon course, a very high speed and flowing track, the car bottomed out on the straight before the final corner, with so much force I was bounced up out of the seat. When I was back in the paddock I checked the video, and it showed the front tyre distorting with the impact. We then checked the wheels, as I'd assumed I'd buckled them. But we found nothing, and on the next two runs, I avoided the centre of the track and stuck to the right. I was told on the track walk, by two marshals on the final bend, that the cars were avoiding the right hand side as there was a yump where they were going light and finding it difficult to slow for the last corner. Fine I thought, stay in the middle. Well I shouldn't have, as the middle of the track was where the surface was uneven, and on a saloon, wouldn't pose a problem. But at 120MPH with a ton of down-force, and with the Mygale suspension compressed, and with no more movement in the dampers, the push-rod took the brunt of the impact, and was clearly weakened.On my last go, T2, with a few seconds to find to catch Smiles and the Simms' Ralt, I was absolutely flat out from the start line, approaching the chicane at 136mph in sixth. I braked, went down from 6th to 3rd gear, turned the wheel right to go around the cone marking the apex, and bang, the push-rod gave up, dropping the rear on to the floor, lifting a front wheel, and when I accelerated, the car span and rolled backwards. I was then stranded in the car, with the sound of the following car getting louder, as they also drove flat out towards the chicane. I waved my arms frantically, fearing the worse, trying to get someone's attention. And then the red flag was shown, and Steve stopped the space framed Audi TT on the chicane, allowing me to get out the car. We pushed it off the track, with a marshal standing on the offside front suspension arm to level the car out, until it was in a safe place, out of the way of the live circuit. The remaining cars then started their runs, whilst I jogged back to the paddock to fetch the van and trailer to recover my poorly car.
My first DNF in three years, a relatively minor accident, but it could have been a lot lot worse, had the pushrod failed at 136mph, I dread to think where I would have ended up.
So a bit of repair work to complete, some uprated push-rods to source, and with two weeks until Snetterton I need to get cracking on with the work, so long as I don't discover damage to the chassis that cant be ignored.
5Jun
Whats next?
Abingdon Carnival this weekend, then Snetterton on the 25/26 June. Abingdon will be a first time for me, so I've a couple of track layouts to learn. Should be fun. Snetterton, thats the 100 circuit, and another opportunity for improving my PB and earning some more championship points.4Jun
Pembrey success
What a weekend! Perfect blue skies and very high temperatures, meant I was able to focus on the dry weather setup, and after breaking my PB on first practice the signs were very good. The front wing still wobbled, until I made some changes to the rear wing angle and added a pair of spacers to the front dampers to restrict their movement, which finally cured it. Over the day I improved my times, as I learnt what down force really felt like, and gradually, run by run I improved, to qualify 12th for the Top 12 run off, which wouldn't be held until the following morning due to the 6pm curfew rapidly approaching. With the celebration music on, I cleaned the tyres, and readied the car for the 1st practice in the morning, which would then immediately be followed by the Saturday Top 12 run offs.The van is much easier to sleep inside with the insulation, sound deadening, and window blinds that I'd installed, and with the 240V hookup point I fitted, I had a heater, fridge, and power for the laptop, its turning in to a real home from home. On to first practice, and I tried an even steeper rear wing angle, and the car was handling better than ever. Then came the Saturday Top 12 run offs, where I yet again set a new PB, and finished 11th, beating Simon Bainbridge and winning another V8 kill sticker for the car.
Next we immediately went in to the first timed runs before lunch, so I had to very rapidly clean all the tyres yet again, refuel with petrol, and I went quicker again. Over lunch I cleaned the tyres for a third time, set another quick time, and qualified 11th for the afternoons Top 12 run offs. Steven Miles had an electrical issue, that meant he couldn't run in the run offs, so that allowed Pete to have a run in 12th place. So we all lined up again, Pete leading off the bunch in 12th, with me in hot pursuit in 11th, and again I improved. On my 2nd run off, I made further gains and recorded another new PB of 98.35s, to #beatpete and also beat Simon again. Another V8 kill sticker for the car.
It was a hectic weekend. On Sunday I did 7 timed runs (1 practice, 2 run offs, 2 timed competitive runs, and 2 run offs), making for a hot and very hectic day. But I really enjoyed driving the car with almost 600kg of down force at 140mph, it was an amazing experience, I grinned almost the entire lap and three quarters. I improved my PB from 2017 by over 6.5seconds, which is entirely down to the 2018 setup including the DJ Racing wings.
The BSC Report for rounds 3 and 4 can be found here http://www.britishsprint.org/meeting_rounds_3&4_2018.htm
Pembrey 2018 resultsThis is the video from my fastest run all weekend. As the wing had wobbled on Saturday I fitted a camera to the floor to monitor its movement. As the memory card in the camera that sits over my shoulder was full (oops) I didn't get any other footage from my final run-off run. Besides, this gives an interesting perspective, and it helps if you know the track layout.
