Thermal management

On the hottest day the UK has ever experienced I was doing a hillclimb. This isn’t a huge surprise as most of the July Gurston meetings I’ve done have been punishingly hot – I remember the Panda dash showing 38 degrees one year. But this was hotter. I’ve never been to an event where sparks from a car ignited the grass. But this happened every time my batch went up the hill.

Previously in this blog I mentioned that I would have a co-driver for the July event, but didn’t mention why or how. Well the story goes like this. Earlier in the year Mark Aley invited me to a simulator session he’d arranged at Classic Simulators in Farnborough. And to liven thing up he said “if Becky beats your time you let her have a drive in your Formula Ford”. No problem I thought. And then got beaten; only by a little bit, but beaten I was. (Even though I sneaked back and went a tiny bit faster..) And as I’m a man of my word, the drive was Becky’s. A bit of work on calendars and we settled on the July Gurston, which happened to be round 1 of the Pre 94 Formula Ford Championship. A shared drive was something I’d never done before. We did a bit of a shakedown test the week before Gurston at Bicester, which showed me that I had little to worry about – Becky drove well and started to show some pace towards the end. And I enjoyed my time as a sort of low rent Ken Tyrrell.

I did the usual thing and arrived at Gurston on the Friday evening and set up in the farmyard. We kicked off the day with a hill walk with Russ Haynes and prepared for the runs up the hill. I can’t remember a time when this has happened before, but on the Saturday we only got two runs because of a couple of reasonably serious “offs”. With the heat and the off’s it must have been a tough one for the marshalls. For me the main thing was perfecting the driver change over, which had to be done pretty quickly because of the running order. And on the Saturday we kind of got there.

By Sunday we were running the car without assistance and got quite slick with the change overs. In the end we ever remembered to change the numbers. Becky became increasingly rapid, convincing me and anyone who cared to watch that she’s going to make a decent hillclimb driver. And I did a PB, 39.08, though I did miss my target time by 9/100’s. If I can make it into the 38’s in August I’ll be pretty happy.

Dual driving was great fun, though it did highlight a problem with the RF84. It was pretty much on the verge of boiling over most of the time. Mark Haynes suggested that the rad might be blocked, and the fact that the fan did almost nothing to cool the engine backed that theory up. A few years ago, when I thought the rad was leaking, but wasn’t, I commissioned a new rad. But didn’t fit it. Seemed like a good idea now. Another clue to the overheating showed itself when I drained the system. The water was far from crystal clear. In fact it took about 15 gallons of water being flushed through it before it was an acceptable colour.

At the time of writing the rad is in and almost everything is connected. The super expensive coolant that promises to make engines run 20 degrees cooler is also in after I ran the engine with plain water and then drained to complete another cleaning cycle. Soon we’ll see if it has worked.

One gear hill

Latest on the list of improvements made to the RF84 is a much slicker gear shift. Yet again never having driven another single seater I didn’t have any idea that the gear shift wasn’t as good as it should be. Though having read comments from people saying that the MK9 Hewland was the best gearbox in the world should have flagged something up. Mine wasn’t. After lots of work, mainly by Peter Sneller, the shift was positive and slick. Well, it was in the garage. The first practice run at Prescott would be the first opportunity to try it in motion.

The weather forecast I saw suggested rain early on, clearing for a dry day. As the first runs started the rain started too, but it stayed wet all day. As I didn’t know that, I left the rear anti-roll bar connected (for the dry runs in the afternoon). The amazing thing about the newly reconfigured gearshift was just how easily the gears just dropped into place.

Allan Rhodes, Motorsport and event photographer. For further information or bookings please email: info@allanrhodes.co.uk or telephone 01242 231096

My experience at Curborough where I kept the car in a lower gear around the first corner and found the whole thing more composed, and a conversation with another competitor a few years back, got me thinking about doing the whole run in 2nd. I tried it and miraculously I wasn’t slowest in the first run. (It was a mixed handicap class for single seaters, with 4 Formula Ford drivers.)

The second practice run was even better. I managed 2nd fastest of the 11 in class. Which is up there with the time I got a trophy. Oddly in a field with a Gould Cosworth in it the 2 fastest cars were FF’s. After the first competetive run I wasn’t 2nd any more but was still quite competetive. A little improvement would get me a few places so I went for it and removed the rear ARB. It looked like the rain was stopping, but luckily it started again before my run. And I managed to go 2 seconds faster! 2nd of the Formula Fords. Happy with that!

Allan Rhodes, Motorsport and event photographer. For further information or bookings please email: info@allanrhodes.co.uk or telephone 01242 231096

Hurried start

A minor medical intervention planned for late 2021, but actually happening in March 2022 meant that my first event of the year was shakedown, test and first event all rolled into one. But on the plus side the weather was perfect at Gurston.

Although it’s fair to say that my preparation wasn’t what it could have been, and that I wasn’t 100% fit (I haven’t done any exercise in over 3 weeks) I didn’t do too badly. I set myself the target of running sub 40s, and managed it on my first official run. Still plenty to sort out, though the engine miss-fire issues of last season seem to have been cured, and the handling was still as good as I remembered. My target for the July meeting is to go sub 39.

Picture by Alex Thake

The observant may have noticed that I’m still running the Van-Diemen.

Picture by Alex Thake

It took some time to get the new sandwich plate and gearbox adapter for the Reynard, but I’ve got them now. Once I’ve sorted a couple of things on the RF84 I’ll get back on putting it all back together. With the newly re-cased Hewland Mk9 and the Quantum shocks the rear end is going to be quite something. I also now have 4 newly powder-coated Wellers, ready for a set of ACB9’s.

The weekend at Gurston also saw my dual driver for the July Formula Ford Festival try the car for size for the first time. (Long story for another time!!) It should be fun getting Becky through a test and the event.

Full Circle

When I was a motorsport obsessed student at Oxford Poly I wrote to every racing car manufacturer I could think of to see if any of them had something, in fact anything, that would make an interesting final year project. I somewhat optimistically informed the British Motorsport Industry that I could make and run finite element models. After a delay due to some issues with the Oxfordshire postal service (the more that things change the more etc.) I received a reply from Malcom Oastler at Reynard, which was great as my room in halls was plastered with posters of Reynard’s. I ended up making a pretty poor finite element model of the 1988 F3000 car for him, but possibly more importantly, visited the Factory in Bicester a few times. You don’t forget things like that.

I have mentioned here before how much better to drive a 70’s Crossle felt than my 1984 Van-Diemen, which got me thinking that another Formula Ford might be the answer to going a bit faster. I vaguely remembered hearing that Reynards from the early 80’s were a pleasure to compete in, and this view was confirmed by a friend (on the pitwall at Silverstone at a test session). He said that an 82 Reynard was the best car he’d ever driven. So, why not I thought, try and get one.

The issue, however, was that early 80’s Reynard FF1600’s aren’t exactly easily come by. (I had actually considered getting one a few years earlier, though I spent so long umming and ahing that it had gone by the time I rang up about it.) There was an 84 in Germany and another in Ireland without engine, gearbox and most of its chassis paintwork.

There was a UK based, decent looking, 83 advertised on a website though. (It took Barbara a lot of searching to find it, but find it she did.) How long it took to actually meet up with its owner, Graham, is part of a long story, and is possibly not one for me to tell. But a couple of weekends ago I found myself in a windswept, rain soaked field in Malvern looking at Reynard #123. Having decided to buy it the small matter of getting out of its trailer, into my trailer and then out of the muddy field presented itself. Which with the help of numerous people we managed to achieve. My car, trailer, trainers and a lot of my clothes ended up caked in mud, some of which is yet to be cleaned off.

The car hasn’t run for a few years so I immediately started work checking everything and making it perfect for the 2022 season. Or as near to that as I can. There are a few cracks in the bodywork that need attention, as well as a reasonably sized hole in the original nose. An unused, more aerodynamic, front end came with the car, which I’m sure I’ll run as soon as I can. The engine is coming out on Wednesday, so I can have a good look at the internals, and lots of bits of the car are already being repainted.. 123 will be as near perfect as I can make it, by March. I can’t wait to actually drive a Reynard after all this time.

Who’d have thought it.. the numbers matter.

There hasn’t been much time to blog recently. Aside from the festival of over commitment that is the rest of my life, hillclimbing activity went up a level. Now the season has ended I’ve got time to sum things up.

In the last blog I mentioned that I was going to Anglesey to try out another Formula Ford on another circuit. Anglesey circuit is astounding, although I was only going to drive a small section of it, thankfully including what has now become one of my favourite corners. Things didn’t start too positively because the car I was down to drive looked a bit, well, like a typical school car. It was a 1976 Crossle, and not as neat as my Van-Diemen. And it was raining. So after a session in a hatchback I took the Crossle out. In the rain; generally I hate driving in the rain. So.. out of the pits and into a reasonably sharp left hander. I turned the wheel in what I thought was about the right way and something really odd happened. The car turned in positively and I felt, well, in control. No feeling that the ancient Irish machine wanted to head straight towards the barrier, spin, or actually do anything other than go round the corner tidily. This was a total contrast to the RF84. And it was pretty wet remember. In fact the Crossle felt grippier, more responsive and safer in the wet than my RF84 in the dry. Something, people, of a revelation. After 10 laps I went back to the pits. And there I had a bit of a de-brief with the instructors, who it turned out all raced Formula Fords. Without going into too much detail we talked about what the issues with my car could be, and I went out a few more times and had a some more really useful discussions. Up until that point I’ve never felt like I was being run by a team, but this felt like it. As you can probably imagine I’ve got nothing but good things to say about the Anglesey Racing School. A proper racing school in an age of “Racing Experiences” and “3 lap supercar blasts”. And I learned to do clutchless upshifts.

Great Chris Coope Image from the August Gurston meeting

It was plain that the geometry/spring/damper setup on the RF84 was somewhat wide of the mark. I had just put the suspension back together pretty much as I’d found it during the rebuild. With the same springs and new Quantum dampers. For my level of driving that would be fine right? That viewpoint was starting to look pretty misguided. I actually walked out of a Bicester garage and said “I didn’t think springs and dampers would be that important”. A monumentally stupid statement, especially from somebody with my background. But it’s less stupid if you add “for somebody of my limited driving ability”. The big change of direction was that I could tell a decent set-up from frankly no set-up. What happened next is why I had no time to blog.

I’m hugely indebted to my friends at Field Farm for their efforts in defining the new RF84 set-up, based on the concept of getting the corner frequency in the right range and going from there. We measured and calculated wheel rates, corner weighted the car and made the wheels point in the right direction. And a stack of other less important things. It has to be said that sitting in a Formula Ford with your hands on the wheel for over an hour is a form of cruel and unusual punishment. But as we will see, worth it for the rewards.

First time out with the new setup, and recently updated gearing, was the Bank Holiday meeting at Gurston. My first run was an OKish 40.7. But after it I texted Mrs Marks and said “it feels like a racing car now”. Over the weekend I managed to put in consistent sub 40 times, but with a miss-fire above 6000rpm that the new gearing and set-up had forced to the top of the issues list. Before I hadn’t noticed it. It also helped having Pete and Jo around whilst I learned the new set-up and approach to racing. If this was serious you could call it driver coaching. When I was at the Gurston and Loton Pre 94 FF rounds I couldn’t work out how I could go any faster. But now I was going faster and could see how I could go faster still. (Fix the missfire for one thing.) The midfield looked like a distinct possibility in the fullness of time. So it turns out car setup is important, even for a driver with distinctly limited reserves of talent. Who knew?

Gurston, August Bank Holiday, Picture by Guy Poole

After Gurston we went testing at Curborough, and I helped out at a Classic F3 test session at Silverstone. Its fair to say that I’m learning the rudiments of car setup and how you approach it. The importance of it all was highlighted at the next Curborough round I did, where my first run was 0.3s inside my previous PB. (Then it rained.) And this was followed up on day one of the HSA season closing event at Curborough in October where I took 1.8s off the time I did on the 2 lap configuration at the same meeting in 2019. That’s a good day at the track.

Curborough, September, Picture by “Through the Eye of Oli”

Needless to say I’m really looking forward to the 2022 season, and the considerable to-do list on the car is going to keep me occupied until the fun starts again.

A Certain Ratio

The last time I blogged, which I see was a little while ago, I was hopeful of getting back to the sort of times I was doing in 2019. I’ve kind of done it, and learned a lot along the way.

Since the first 2 Curborough rounds I’ve done a Prescott; mixed conditions and not fast enough, Gurston; pretty much on the pace of 2019, and a Loton. Which was very wet at times but more of that later.

There’s not much to say about the Prescott event, which was notable mainly for the fence between the somewhat sparse spectators and competitors. Wet but drying through the day, resulting in a best time 1.2s slower than my best in 2018. I’ll blame the conditions.

Gurston was an altogether different matter. I’ve been to some really hot Gurston events, but this was the hottest. When I put the ignition on the temperature went up to 40C. Without running the engine. The marshalls were running the event so that the queue for the hill was kept to 2 or 3 cars – so it was a matter of firing up the engine and driving to the line and going. Ironically I was running the engine colder than ever before and it liked it; seemed happier revving, and I was quick across the line. Quite quick and still in 3rd. I managed to match my second best time and it got me thinking about gearing.

The other competitors in Pre 94 FF were super helpful with advice on ratios, and when I checked the gearing I was running it was somewhat longer than anyone else was using. If ever they run a sprint at Indianapolis I’ll have some ideal cogs. Armed with the info from Charlie, Les and Peter, I purchased some new ratios from Mark Bailey who was also super helpful. Essentially 3rd became 4th and 2rd and 3rd filled the gap above 1st which I kept. Jo White gave me a masterclass in changing ratio’s in a Hewland MK9.

The first opportunity to try the new gearing was at the Pre 94 FF round at Loton at the weekend. (Beware the book of excuses is in play from now on.) Conditions couldn’t have been more different from Gurston. I don’t think I could have overheated the engine had I wanted to. And at times it was very wet. Difficult to believe it was August. On the first run I couldn’t believe the difference the new gearing had made. Even though the run was dry every time I touched the throttle on the way out of a corner the back started to slide. Different driving style required and almost certainly some adjustment to ARB or dampers.

Photo by Rob Mcdonald

I last ran at Loton in 2017 in the Panda. I was pretty sure I remembered it. But one corner repeatedly threw me a curved ball. Fallow at the top of the hill is a lot further away than I remembered.. That doesn’t make sense so I’ll try again. When you approach Fallow it looks like the corner starts about 50 metres before it actually does. And on the first couple of runs I braked crazily too early. Which was a surprise given that when I was driving the Panda I used to be pretty aggressive here. 4 years is a reasonable amount of time I guess.

And finally the last issue that I had to sort out was a lack of speed on the Cedar Straight. Which isn’t straight. Thanks go to Charlie Reilly who told me that I needed to be in 3rd through the section before the straight, which increased my speed on the straight a lot. I didn’t set the world on fire at Loton (whereas Tom Weaver did with the times he was putting in) but it is still my favourite hill.

So next up I’ve got a session at Anglesey in one of their Formula Fords, simply to get some more seat time and to see what a different car feels like, another Gurston where I hope the new gearing pays dividends, and hopefully the MAC meeting at Curborough in September if my entry has been accepted.

Getting back on track

It was pretty tough getting entries at the end of 2020. I didn’t get out. But 2021 has been different.

I’ve already done two meetings in 2021. Both at Curborough. It’s great to be back.

I’m not exactly at the front of the pack when it comes to outright speed, but the amount of this speed that I’d lost over the enforced break was a bit of a shocker. 16 months without driving a racing car is a long time. I thought that I was actually slower than I’d been in the Panda; that wasn’t the case, but it was a close run thing.

The April meeting was fun, and I pretty much classed it as a shakedown. I needed to be more competitive in May. Luckily I finally found a Curborough simulator track and managed to put in a decent session in a virtual Formula Ford, which seems an unlikely clash of technologies. The results were really interesting.

My first runs are generally warm up/shake down runs, but this time I was more focused on what I needed to do from the off. And I managed to put some of the things I’d practiced into action from the off too. My line at flagpole is much improved. The sim session showed that you could go through the crossing faster than I do in real life, and in the sim I was settling the car with a bit of left foot braking there, which I didn’t do for real this time. The sim session had somehow improved how I approached the circuit and driving it.

In the first run I managed to select 3rd instead of second for the middle but of the run, meaning the car didn’t pull at all. Sorted that for the other 2, though I think it’s screaming a bit in second. Upshot was that I was over 2 seconds faster in May than April. And managed to come 2nd out 3 in my class.

Unless I enter some other rounds this year I won’t be back at Curborough until the HSA end of season event in October, where I’d expect to see a much bigger entry. By then I’ll have done some more time in the sim and a few more rounds. Hopefully I’ll be down to the sorts of times I was doing in the summer of 2019.

Pictures from the May meeting by Peter Scherer

If I can’t draw it, then I don’t understand it

This blog originally started with something about how James Hunt is a big figure in motorsport, then finally totally lost its way describing people I’ve met in the last couple of years.  The last thing this needs to be is a linked-in style, “isn’t everyone wonderful, aren’t I amazing” posting.  For the record the parties involved are listed at the end of this.  Much more appropriate.

So instead, something a bit more factual.  I’ve become peripherally involved in a project to restore the two Dastle F3 cars run by Hesketh in the 1972 season.  These cars are relatively well documented if you take the time to look.  F3history.co.uk has some pictures (http://www.f3history.co.uk/Manufacturers/Dastle/dastle.htm) and a brief chronology, and there are podcasts and even TV interviews which cover the early history of the Hesketh team. Even ebay managed to serve up a print of the classic Druids formation shot.  So there’s no real need to cover the same ground here.

What I’m going to talk about here is something more specific to the world of CAE that I inhabit.  When I rebuilt my Van-Diemen RF84 I started to draw it as I went along.  The idea was to have a reference for new parts and to understand how it went together; but that project went nowhere when I struggled to get the nascent CAD system I’d chosen to actually model a complete car and I discovered that I could buy everything I needed off the shelf from Ken and Simon at Universal.  But the Dastle project is different.  There is no Universal Racing Services for Dastles, and knowledge of how they work isn’t easily come by.  So this time a model seemed a necessity rather than a luxury, and something I can contribute to the project.  To quote Albert Einstein – “If I can’t draw it, then I don’t understand it”.

Being a simulation engineer my plan is to create a simple representation and add complexity as needed.  Already this process is yielding huge benefits, for me at least.  In the total absence of drawings, notes and calculations it’s allowing us to get inside the head of the designer (Geoff Rumble according to f3history.co.uk  – if you are still out there Geoff I’ve got a 1000 questions for you) and reconstruct the most important thing – the original design intent.  You can’t get that by pointing a hairdryer at the car.  Some parts will need scanning, though not as many as people might imagine; mostly this is about putting in the hours with a tape measure, rule and vernier.  And taking enough photo’s, which I almost never do.

This is definitely “a how it started” post.  A real work in progress; I’ll post updates as the model is developed.  As usual a CAE representation has generated significantly more questions than answers and prompted a lot of thought about what the design intent was.  The overarching question for me is what was designed and what just happened as the cars were manufactured.  The model won’t be able to answer that; talking to right people and looking at contemporary references may help there (I’ve got a copy of Racing Car Design and Development by Terry and Baker which may shed some light on the design process in the early 70’s).  But the model does provide a focus for this activity and a means of understanding how things function and how they can be engineered to run properly again. At the very least it’s something to point at and scribble over whilst we try to work out a strategy for the restoration process.

And as the man said “If I can’t draw it, then I don’t understand it”.  TBC.

Who’s who section:

BIOS-Sport: Peter Sneller and Arthur Griffin (Arthur drew the wheels and tyres)

Classic and Sports Finance: Robert Johnson (Owner)

The one where I don’t make a wind tunnel model.

I hate friends.  No idea why I used a Friends type title.  Anyway.  This is about me not making a wind tunnel model.

wt1

Unless you are supremely gifted, and as we all know I’m not, your first goes at anything are likely to be a bit, well, er, rubbish. In fact I personally don’t think a typical person can learn to do something unless they actually enjoy being crap at it. So you have to get in there, have a go, mess up and then see where it all ends up.  (36 years after making my first toy aeroplane I won an event at the Nationals, so it isn’t always a rapid process.)  Where I’m headed with racing cars means that I need to get a grip on aero (see previous stuff on CFD) and that means wind tunnel testing in some form.  Which means I needed to get in there and mess up a wind tunnel model.

I used to exchange tweets with the recently departed and already much missed Richard Divila.  And in one exchange he said that I’d be surprised how much you could learn from a really basic wind tunnel.  And I guess that means from a pretty basic model.  My son, is, as I write this, finishing his dissertation, which might not surprise people to learn is a CFD study of a racing car.  In fact the one I used to form the basis of Openfoam work in the last blog.  And for that the initial intention was to do some wind tunnel validation of his Fluent work.  It’s entirely possible that even without Covid19 we might not have got round to it.  But I did get what is very much a comic book first hack out of my system.  And that’s a good thing; it really is, because it gets you somewhere good.   So what have I learned

You can’t 3D print everything: Unlike the current UK government I don’t think 3D printing is the only manufacturing show in town.  It plainly isn’t, but this project was my excuse to get a printer.  I chose to get a Dremel because I love their stuff.  It was a great choice and their aftersales service is really good, mind you it had to be after the first one didn’t really work.  And I’ve learned a lot, especially about DFM, (Design for Manufacture) in this specific instance. I’ve been suprised in a good way about some of the stuff I’ve managed to make and surprised in a bad way.  I still haven’t changed my mind about the fact that 3D printing, at least with the machines I’ve used, is like machining something on a worn out milling machine – you can do it but it takes a lot of effort.  But I am pretty sure I could make half decent body panels for models up to about 20%.   What really aren’t good enough are the wheels.  They didn’t ever come out well enough, especially when I can machine a set from solid quite easily.

printer

One area where the printer really comes into its own is the production of small brackets.  These can be produced quickly in reasonable batches.  You’ve got to love that.

Anything that involves thin flat sections should be made from thin flat material, because if you print these you need to make them significantly thicker than scale and the surface finish won’t be good enough. A small CNC milling machine would be really useful here. Floor components, wing end plates and other bits could be profiled from thin carbon fibre sheet.  The results would be pretty good.

Plainly to be useful the model needs to be very adjustable, and in its current form it isn’t.  Ride height and rake need to be controlled very accurately.  I’d say that what I need is some form of cross slide arrangement to support the model from a sting.  Ebay appears to be awash with them. So that’s that sorted.  Another thing that needs to be easily adjusted is wing position and angle of attack. I’ve thought long and hard about this and the only really neat solution is to use a series of mounting plates of different dimensions.  That small CNC mill again.  And finally the hack model uses a completely 3D printed tub.  What it really needs, and I’ve heard this from several sources is a central spine, which is what joins the model to the sting and the wings to the model.

wip

And finally the wings.  Obviously these have to be pretty accurate, and the ones I made kind of were.  They were printed in vertical sections and then assembled on a carbon rod. As a first stab OK and they would have been reasonably representative. At a larger scale I think this approach would have been fine.  So lets describe wing manufacture as a work in progress.  But at least we are in the game now.

It’s quite unlikely that this not really good enough model will ever see the inside of a wind tunnel. (With a bit more work it would be a useful exercise though) But it has taught me a lot about making things with AM and what a useful model might actually be like.  So not building a wind tunnel model has been a hugely useful exercise if I ever do it for real.  Meanwhile the CFD activity continues..

f750_3

 

Frei Aeroworks..

Back to blogging; I’m certainly not doing much driving.  My blogs aren’t popular at work these days, so its a kind of mixed CAE/racing car offering here this time.

CFD_Image_11

I’m convinced that in the Tony Southgate autobiography he says that there was a time when you could increase the downforce a car had by a third in an afternoon in the windtunnel.  (As an aside I managed to get hold of a copy of this before the price got crazy, it’s on Amazon for £550 at the moment. It’s good, but not that good.) Problem is that I can’t find that reference.  Maybe its in one of the other designer biographies; if its in the Murray book I’ll need to get training before I try to pick it up.  Maybe I imagined it.

Anyway, it struck me that much of the club racing scene must be operating like that still.  People put wings on cars and run floors and diffusers. But how optimised are these generally?  Not very I’d say, admittedly from a position of near complete ignorance.  Modern high end aero packages are designed and optimised using wind tunnels and Computational Fluid Dynamics, way beyond the scope of the average competitor.  Its how far beyond that I set out to discover.  It would be a lot of fun right?  Is there still the scope for big gains made relatively easily?  First, for me anyway, the easy bit. CFD.

Openfoam has been something of a curiosity for me for some time.  It’s a really decent CFD code, used by at least three F1 operations to my knowledge, and its free.  Not free like Nastran; that’s not really usuable in its free form.  Openfoam is free and really good.  But because there aren’t any decent free pre-processors (the bit where you actually build the model rather than solve the equations) I hadn’t tried it.  I’m not entirely sure how I stumbled across the FreeCAD openfoam pre-processor. But stumble across it I did.  And frankly its bloody marvellous.  The test was to see if I could create a vaguely useful, full vehicle CFD model that could tell me useful stuff.  Currently I only have an 8 core machine (with a low end GPU) so that set an upper limit on what could be achieved.  Anything I did had to mesh in less than 1/2hr and solve over night.

CFD_Image_3

Luckily my son has created a car model for his final year project.  Its a model of Jo White’s latest, so ideal on many levels.  Before attempting a full vehicle I ran through a few self created tutorials that I used to learn the system, especially the mesher, which as things went on seemed better and better.  Its a free version of a commercial program called CF Mesh written in Zagreb by a company called Creative Fields. If the idea of the free code is to publicise their work its certainly done its job.  Getting the CAD model right for meshing was the usual headache, but no different to other CFD codes I’ve used.  One thing that I thought might become a headache was selecting the internal faces of the flow volume for boundary conditions and mesh refinement.  I kind of stumbled into how you did this, and that meant the whole car workflow was feasible..  Another interesting thing about FreeCAD is that its all scriptable in python.  Which means I might be able to automate the whole process at some point, which would be really neat.

Paraview is another free program that is little short of incredible.  Its free, amazingly functional and again can be scripted. All the results here were plotted with it.

So the upshot of all this is very promising.  This is CFD, and I guess you need to know a bit about what you are doing, so its not for everyone.  But the results I’ve got so far with meshing times less than 1/2hr and solves of  3 to 4 hrs have been very encouraging.  I still need to add a moving floor (I know how you do it, just haven’t yet) and look at ways of doing drag/downforce calculations for more than just the whole car.  But I think I’ve proven that this sort of thing can be down at no more cost than that of the hardware. (Which now makes me want a 16 core machine for my office at home.)  This, I think, has big implications for club motorsport competitors, or  if not them, the smallest car constructors.  If you are the sort of person who is happy to hack about without support or training, and is as interested in the process as the result, this is really something. What we need now is a low cost wind tunnel to validate everything!

As an addendum to the above I’ve also been using a free multi-body dynamics code called FreeDyn.  I’ll probably blog about it at some point in the future.. It looks like it could be the MBD openfoam.

free_dyn_4

And I’ve also been playing with rendering.. which gets me thinking about doing an OF model of Matt’s MW01.  There’s a whole lot to do.. its just about finding the time.

render_1