Sprinting an ADR Sport 2

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flynfrog
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Re: Sprinting an ADR Sport 2

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andylaurence
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Joined: 19 Jul 2011, 15:35

Re: Sprinting an ADR Sport 2

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Handy link, thanks! The tunnels are off the cards for now as there's too many things that need changing to accomodate them (radiator, exhaust and oil cooler being most significant). I'm making the best of the flat floor I have right now. Just 6 weeks to the start of the season, so it's a bit of a fight to be ready in time!

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andylaurence
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Re: Sprinting an ADR Sport 2

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I just about made it to Mallory Park on Sunday for the first sprint of the year. I arrived soon after 08:00 to find a big queue for scrutineering. True to form, I got to the scrutineering bay just as the drivers' briefing started. Immediately afterwards, I hopped into the car for the convoy run. Having spent some time playing with the gear linkage after the problems at Llandow last year and having had a misfire on the Friday night, I was keen to do a systems check from the driver's seat. The gear linkage is fantastic with a tactile feel and each gear engaging with an encouraging click. The misfire had also gone, which was good news.

Less good news was that it was damp and I was on slicks that were still at 25psi for travelling. Wheelspin at part throttle in 3rd gear is not what I'd call normal. Worse was to come though, as whilst waiting for my practice run, it started to rain. Rain quickly turned to snow and I was on slicks. Seeing rooster tails from the other cars, I decided to call it day as I have no wets and went home. Strangely, just a few miles away at Curborough, it was bone dry - I should've tried to get a late entry on the way home!

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andylaurence
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Re: Sprinting an ADR Sport 2

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Mallory Park wasn't the best start to the season, going home after the convoy runs. I bought some part-worn wets during the week to be sure I didn't have to go home if it rained. Yet again, it snowed! Luckily, despite the temperature and precipitation, the car was able to run on the new (but very old) wet tyres. I don't know how old they were, but they're supposedly Formula Renault/BMW tyres, so they were not that soft when new in hillclimb/sprint terms and I discovered that these are particularly non-soft when I saw that the car was only generating 0.7G in the corners!

I didn't manage to complete practice without missing The Esses on the first lap and having a big oversteery moment on the exit of that same corner on the second lap. Every other corner was nearly as bad and I was experiencing wheelspin in every gear down the straights, barely breaking 100mph all the way through. On the first timed run, I managed to nurse the car all the way to Bobbies on the second lap before out-braking myself and missing the chicane. That left everything to the final run and it dried out sufficiently that slicks were viable. I went substantially quicker, but a rear wing mount sheared on the second lap causing a big vibration at the rear and I lifted off down the straights, wondering what it was. Despite this, it was good enough for the class win and a good haul of points in both the Bristol Speed Championship and the ASWMC Sprint Championship.

So what can I learn from this? Let's compare the best run this year with last year's best. The weather was much better last year, but this was before the hubs/wheels were upgraded and before the rear wing was altered. The first thing to note is that the run was around 15 seconds slower this year; an absolute age. Off the line, I lost 3 seconds in the first 80 metres. This is no doubt down to the freezing temperatures and because the tyres had not been used at all that day and as a result had no residual heat in them. After 40 metres, I was 14mph slower this year, yet by 230 metres, I was just 3mph slower. The car was clearly accelerating better, notably moreso at higher speeds. At this point, I missed a gear change and lost a bit of time. Unknowing of the conditions, I then proceeded to lose two whole seconds over Avon Rise and in the braking zone for Quarry.

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The apex speed for Quarry was 8mph down on last year, but by the end of the farm straight, just 4mph slower. That loss in apex speed carried down the straight lost a second before braking for The Esses. The braking point was similar but, interestingly, the deceleration was greater this year, showing there was scope for improvement last year. The first apex was 8mph slower than last year and the second a whole 10mph slower, possibly because I'd straight-lined the bit between the apices a little too much and that made the second half artificially tight.

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The acceleration out of The Esses meant I was travelling just 3mph slower at turn-in to Old Paddock, but instead of taking it flat, I took a heavy lift, losing two tenths through the corner and being 13mph down on the exit. By the time I got off the throttle heading towards Tower, I was just 3mph slower, but 6 tenths had been lost in the process. A further 7 tenths escaped before the apex at Tower, where I was 5mph slower on the apex. This, however, allowed me to get on the throttle earlier and the speed to Bobbies was matched, although 3 tenths had ebbed away before that happened.

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Into Bobbies, I braked a little earlier this year, but only a tenth and a half lost. At this point, we reach a corner where this year was quicker. A 13mph higher apex speed led to a gain of half a second over last year's time. By the exit, the speeds were matched and this continued all the way to the same braking point for Camp. A quicker transition from throttle to brake led to a slightly lower speed this year and I stayed longer on the brakes, resulting in an apex speed 5mph slower and 3 tenths lost. A further 3 tenths went on the way to Folly, by which time the 9mph difference from the exit caused by a late apex had been reduced to just 1mph. I lifted through Folly as I heard the rear wing chattering on its mounting.

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Instead of going flat over Avon Rise, I braked being up to 25mph slower than last year and this cost two seconds before the apex at Quarry. The chattering noise at the rear was unnerving and I wasn't sure of the cause at this point. Despite being 8mph slower at the apex of Quarry, I was going quicker at the end of the Farm Straight. I braked slightly earlier, losing a tenth, but carried good corner speed through The Esses. This good speed through The Esses compromised the exit speed and half a second was lost to Old Paddock. A lift through Old Paddock again lost 6 tenths through Hammerdown.

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I lifted early again for Tower, coasting to the 6mph slower apex and losing over a second in the process. Interestingly, I braked 30 metres later for Bobbies, partly because of the lower approach speed, but also because I carried 13mph extra into Bobbies, which gained half a second.

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In summary, it appears that I've learned a bit more about how much pace I can carry into Bobbies, but that I was more tentative than I needed to be through the rest of the lap. It also seems that the car is quicker in a straight line, which suggests that the rear wing relocation has been successful in reducing drag, even over the small wing used last year. It's hard to see if grip has been reduced as a result of the downforce because of the vastly different conditions.

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andylaurence
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Joined: 19 Jul 2011, 15:35

ASWMC Sprint Championship Round 2: Catch the Pigeon Sprint

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It's my bogey track. I entered twice last year and missed both. I broke the ADR the event before the first round at Clay Pigeon and didn't get it fixed in time. At the second event, I got almost all the way there before my tow car left me stranded. This time, I saw the paddock, so it started well. I also managed to walk the track, so that was good too!

In first practice, my camera wouldn't start, but I recorded a time that was close enough to be happy, despite catching the throttle under braking and nearly leaving the track. Second practice left me filled with confidence. So much so, that I had a spin at the second corner. Still, the second lap was quick, so that was good news.

In the afternoon, there were three timed runs and I needed them. On the first corner of the first run, the throttle stuck open and I was lucky to keep on the track. I hit the kill switch when I was sure the throttle was sticking and got a tow in - better to do that than bin it or pop the engine. After some investigation in the paddock, I couldn't see anything that was causing the sticking. The throttle cable was in perfect condition, there was no snagging and the movement was fluid. Was it my foot that had done it? Unsure, I headed out for the second run. I had three runs, so I could afford to cruise around and give myself enough time under braking to dip the clutch and hit the kill switch if anything went wrong. What I didn't plan to do was hit the kill switch on the up-change out of the final corner of the first lap. Needless to say the kill switch is being moved before Llandow!

That left it all to the final run and I still didn't know if the sticky throttle was the car or my foot. I took a tentative first lap and then pushed harder on the second lap. I'd broken the class record, but not by as much as Luke Trotman, who took the win in his Mallock. When I got home, I discovered that the data logger hadn't worked and I had no data, so the data debug will be limited and a new logger is on the list of things to do.

The only data I have is gathered from the video, so I've taken apex speeds and peak speeds on the straights. Top speed was just 68mph and the lowest speed was a paltry 26mph. It's safe to say this track is not dominated by aero. In fact, it probably has very little effect at all. The average apex speed was 35mph and the average top speed on the straights was barely over 50mph.

Here's the video.

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andylaurence
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Joined: 19 Jul 2011, 15:35

ASWMC Sprint Championship Round 3: Llandow Sprint

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Clay Pigeon isn't my only bogey track. I'd not made it to Llandow either, aside from a half-day test session last Summer. I had to pull my entry thanks to a wheel failure and a breakdown in the tow car last year, just like Clay Pigeon.

This year, I arrived to find a rather damp track. It wasn't wet though, so the slicks stayed on. The track was slippy, but I discovered the kerbs were slippier when I touched one and exited stage left (but right side first). Side-stepping the clutch soon got me back underway and I somehow finished the first practice run fastest in class. Clearly everyone else was running wets or having a slow start.

In second practice, I managed to stall the car going to the line. My starter pack was helpfully retrieved by Nick (cheers!) and I was able to restart the engine. Coming down the back straight on the second lap, I could hear a loud metallic vibration and I saw red flags waving. Slowing down, the noise abated and I saw Tom's car stranded next to the track, a victim of an ECU failure. As I slowed down, I started to feel the vibration much stronger and it felt like a wheel was going to come off (again!) so I stopped.

After hopping out the car, I could see nothing obvious and the wheels were attached. As the Clerk of the Course arrived, I spotted the swarf beneath the chain. The tensioner had failed again and the car was immobile. The only recovery at Llandow was a rope on the back of the truck, so I hitched a lift back to the paddock and recovered the car on my trailer.

Having annoyed all my fellow competitors with a 15 minute stoppage, I returned back to my paddock space to find a bunch of them stood around wielding pry bars, drills and screwdrivers. They were out to get me ... on track! This is what club motorsport is all about and a load of truly awesome people skipped lunch and got up to their elbows in oily stuff to get the car fixed.

Dave provided a pry bar to get the tensioner un-tensioned and it was soon in my hands. A few swift blows with a mallett and screwdriver got it close to its original shape, but the bottom was properly mangled and needed Brian's file and Julian's trailer-mounted vice to get the sprocket spinning again. Once back in place, a new strap was fabricated from scraps of aluminium and screwed in place with Andrew's screws. A piece of aluminium angle replaced the missing metal on the tensioner mount and after fitting my new chain, the car could drive again.

The rattle I'd heard down the straight was a different problem. I discovered the cause as the car was recovered onto the trailer. A floor bolt had come adrift (probably on one of the kerbs) and the floor was hanging down. A suitable replacement couldn't be found, but ample lockwire did the job. I was ready for the timed runs and I was almost due out. Julian didn't get to his car until Nick brought the double-driven car back into the paddock to swap drivers.

Heading out in the first timed run, I had a few gear selection troubles, but I put a time in and that was good enough to lead the class by 7 seconds. It was raining during the run, so there was the chance I could be beaten - I've seen people gain 7 seconds on the last run when conditions have not changed all day. I had to do another run, whether the car would do it or not. It was dry now and the sun was out. It wasn't a great run, but a second improvement was enough to take the win by a big enough margin for 21 points. I'd have been lucky to get more points by breaking the record!

A testing day, but the end result was a win and an extension of my ASWMC Sprint Championship lead by a whole point and that's all I could have hoped for. Here's the video to see my maladies.

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andylaurence
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Joined: 19 Jul 2011, 15:35

Low Wing Analysis

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People keep talking about the rear wing and its placement behind the rear arches. Comments vary from "does it work like that" to "you're an idiot if you think that'll work" and everything inbetween. After the off at Castle Combe, mud sprayed onto the bottom of the wing and the distribution of the dirt showed that the air was attached to the underside of the wing.

I've been playing around with Khamsin, a plug-in for Sketchup, and thought this might be the starting point for some analysis. I drew a basic side profile of the ADR, extruded it out and added in the wing elements in the appropriate place. It's amazing how quickly this sort of thing can be done in Sketchup! I made three components (body, main plane and flap), copied them into a virtual wind tunnel, configured Khamsin and started the analysis. The results clearly showed that in the centre of the car, the rear wing is working effectively.

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I then did the same using the shape of the rear wheel arches and, whilst the effect isn't so great, the wing is still clearly effective.

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What intrigued me next was to see what a 500mm diffuser would do to the results, so I drew one and re-ran the simulation. The results were dramatic with the rear wing driving the diffuser hard. The figures showed that the downforce had increased by 45% and the drag had reduced by 11%! Admittedly, this is far too simplified to be taken seriously, but it correlates with the "mud-viz" used at Combe and suggests that a new diffuser will really improve downforce for little or no drag penalty. It's next on the list!

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proutyc
proutyc
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Joined: 08 Jun 2010, 05:19

Re: Sprinting an ADR Sport 2

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Awesome piece of work. How easy was that to draft up?

I have a similar car and am wondering about the wing placement and diffuser. (My diffuser is actually 520mm high)

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andylaurence
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Joined: 19 Jul 2011, 15:35

Re: Sprinting an ADR Sport 2

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It took about 15 minutes to draw the body/wing (I traced a side-on photo and extruded out). Processing took less than that time and using Ensight to render takes about 5 minutes. For all the lovely pictures above, it took about an hour of effort. Of course, it doesn't tell me too much, but is interesting all the same. It's clear that the wheel arches do affect the wing, for example.

What car do you have and why/how is the diffuser is so large? The one I've drawn above is only 250mm tall, although there's scope to make it much bigger.

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andylaurence
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Re: Sprinting an ADR Sport 2

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Two years ago, Crystal Palace was the venue for my fourth sprint. I was surprised and pleased at the time to do quite well, leaving with two class wins and a top 3 overall. With two seasons of experience behind me and two years developing the car, I thought this year might be more successful. Then the entry list came out. A factory Radical SR8 driven by an experienced and talented racing driver and the existing class record holder in his 480bhp V8-powered Pilbeam hinted that I might not have it all my own way.

I arrived at the venue raring to go and drove down the hill to the paddock via the finish line, partly because there's a steep change in gradient that smacks the splitter and partly because it's a lovely drive around the outside of the track. At scrutineering, I was again hauled up on the unorthodox wing position, but my Blue Book now falls open on the right page, so proving eligibility was simple enough. For the first run, the car was misfiring badly and I stalled several times to the line (thanks to everyone who helped restart me!) before heading off. On the first upshift, the gear lever came away in my hand. I'd used a 4mm bolt to avoid the shaft, but as the helpful Radical engineer explained back in the paddock, the reason for the larger bolt is to stop it falling off. 5mm bolt re-fitted with two new plugs (yes, it was running on two cylinders - 500cc and 90bhp) and I could take some time off my 39.60 from first practice.

Second practice went better, but I braked too early for the first corner, was hesitant through turn 2, taking an early turn-in. Again, I was early on the brakes into the hairpin and turned in too early, getting on the throttle late as a result. I locked the rear on the downshift into the chicane, arriving on opposite lock and being late on the throttle on the exit. I was also hesitant through North Tower bend, picking up a new bit of information for next time round. Despite the areas I could improve, I still managed a PB of 35.58.

Buoyed by a good practice and leading the class at the time, I was confident for the afternoon. Unfortunately, the afternoon was a dead-loss. Heading into the hairpin, I brushed the throttle when I hit the brakes. Given that I was concentrating on braking as late as possible, there was no margin and I headed for the tyres at an uncomfortable pace. Knowing the tyres are at an angle, I coaxed the nose into the corner to give myself more slowing down time. I hit the bank with enough force that it slowed me down enough to miss the tyres, but that broke the pushrod. The pushrod wedged itself into the wishbone clevis, which allowed me to drive back to the paddock, but it was game over for the day.

Overnight, a fellow competitor fabricated a new pushrod and I had it fitted by 06:30, ready to drive down and sign on. The weather was fantastic, but the guys the day before had been stonkingly quick. I'd watched from the outside of turn two leading to the hairpin and Roger Green was incredible. A drive that deserved FTD, but a big car like that on circuit wets would never have been able to do it. He did take the class record though and David was out to prove himself by slaughtering me and taking that record back.

First practice was a shakedown after the confidence-knocking shunt of the previous day. I locked up into the first corner and carried first gear to the hairpin, being very tentative. I locked up again on the downshift into the chicane and was tentative into North Tower, but pushed on through to try and find the limit through the second half. The result was a 37.97.

The gloves came off in second practice and I went to put in a time. I hit the limiter by the apex in turn 2, so made a note to upshift before turn-in next time. I had understeer at the hairpin, which led to running wide and being late on the throttle. The result was 35.37 and a new PB.

In the afternoon, my first timed run was what can only be described as EPIC! I couldn't fault it and it netted me a 34 second run. I was second in class, but with Gary amalgamated from the single seater class and bound to take FTD, a class win was on the cards. I was just a tenth clear of David in his Pilbeam, but with nothing more to give, I was certain that he'd scalp me in the next two runs.

In the second timed run, the throttle cable snapped just before the hairpin and I rolled back into the paddock under marshal-power - thanks, guys! David was kind enough to give me a spare cable and all the guys in class (plus a helpful passing racer) jumped on the car to get me ready for one last run. I lined up ready for one last hurrah, but no expectations of going quicker, especially as there was oil down on the exit of the hairpin.

I gave it too much into turn 1, missing the apex slightly. I slightly dodgy turn-in to turn 2 suggested it might possibly be flat. 76mph down the short straight into the hairpin, I again got mid-corner understeer fron the still cold left-front tyre. I countered it with a stab on the throttle and a bit more lock, keeping tight on the exit to avoid the oil. I wasn't late enough on the brakes into the chicane and then tentative into North Tower, but hot through the finish. The result was a new class record, a class win and 2nd overall.

Thanks to all the guys who helped me that weekend, whether a hand on the bodywork, fabricating parts or stood on a marshals' post. If you were not there, things would not have worked out for me. Here's the video of what you made possible...

There's clearly some work to do, so I've dropped the car off with Jo White at Vulcan Dezign to make permanent fixes for the temporary fixes of last weekend, work on the brakes that keep locking too easily and do some aero mods. I'll be picking it up again and heading straight to Abingdon Carnival on Saturday to try and score maximum points!

stez90
stez90
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Joined: 10 Jul 2012, 23:31

Re: Sprinting an ADR Sport 2

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Hi!
Just subscribed to this topic, very interesting.
Since you need to reconstruct the 3D shape in order to make CFD tests, I suggest you to use PPT-gui (Python photogrammetry toolbox). It's free and open source and if used correctly it gives you a quite accurate point cloud that you can use as a base for modelling a correct shape. Not as accurate as a laser scan, but still good enough, expecially in non-glossy/non-reflective areas.
As simple as making a lot of photos!
Check also 123d catch by Autodesk, similar software but with different output (only interpolated meshes, less accurate than plain point clouds).

http://arc-team-open-research.blogspot. ... s-and.html

Here some example of what I achieved:
https://www.dropbox.com/s/crwjxyy7kxwpv ... shot00.png
https://www.dropbox.com/s/z49zo57uysfie ... shot01.png
https://www.dropbox.com/s/h260mbtqzuxw8 ... shot02.png
https://www.dropbox.com/s/nz2u2pg83kzsc ... shot03.png

Hope this help your aero development! :D

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andylaurence
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Joined: 19 Jul 2011, 15:35

Re: Sprinting an ADR Sport 2

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Thanks for the link. It's something I've looked at before, but never fully investigated. I'll take a longer look at another point. Perhaps I'll get a few photos of the car ready for when I have time to analyse. It'd be great to be able to test a more accurate model, but I'm aware that a lot of air passes through the body, rather than around it, which will make it hard to model accurately. Also, I'm simulating without rotating wheels, which makes a massive difference. I've a new data logger on its way that will allow me to hook up four suspension pots. I'll be able to use those to measure downforce practically directly and some coast-down tests will give me some indication of drag.

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RicME85
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Joined: 09 Feb 2012, 13:11
Location: Derby

Re: Sprinting an ADR Sport 2

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even better would be to pick up a cheap Kinect unit and use that to take a 3d scan

stez90
stez90
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Joined: 10 Jul 2012, 23:31

Re: Sprinting an ADR Sport 2

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Yes, if you already have a kinect.. :D

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RicME85
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Joined: 09 Feb 2012, 13:11
Location: Derby

Re: Sprinting an ADR Sport 2

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can pick a second hand one up for £30