I belive the regs mean bottom of seat as opposed to seat of bottom !

Hi Ashley
We are in a simular situation but with the minimum ground clearance. Its a bit more obvious for how low the car seat can be as it can only be measured to the under floor of the car at its lowest point; I would imagine it will be the same for maximum height to be again measured from car under floor to flat surface. Hope you get a difinative answer from Admin and that it works in your favour. We are looking at taller tyres to get over our issue.

Mr T

I've assumed the seat height regulation to be the distance from the ground to the upper surface of the seat where the drivers will park their backsides, a measurement to the underside of the seat doesn't achieve anything definitive in terms of reducing the CofG height (the stated intention of these rules) as the seat base may be very thick and the driver therefore sitting significantly more than 100mm above the ground.

Farnorth is correct. The measurement will be to the upper surface of the seat, where the driver sits.

Admin.

Oh dear, going to have to do something drastic, our problem is we have two cross beams under the chassis and they are 60mm high. Going to have to think a bit more on hoe to achieve this, seems crazy to have to modify again next year
Ashley.

Minimum ground clearance must be the distance from the ground level to the lowest part of the car being 30mm, this has been checked in the past by sliding a batten under the car at scrutineering. The seat base and battery base being no higher than 100mm.
It is going to be very difficult to measure to the top of the seat surface unless a hole is cut through to accomodate a measuring tool. It says the the 2012 Regulation T5.2 is not changing for 2013.

I can't find proposed regs for 2013 at the moment, but I know ground clearance is not changing but I am sure there was something about seat height and battery Height.

Come on admin...........the base of a drivers seat is just that, otherwise you would have to specify the 'top surface of the driver's seat' which at present is not specified. Shrews makes a good point. Semantics is getting in the way here. Ground clearance is ground clearance surely.

CC

This argument comes up again and again both here, in a previous competition I did and at work... it's more about the spirit of the rules/standards than the letter. It's pretty obvious that if the rules show a minimum or maximum dimension they're trying to get you to do something for a reason rather than making a dimension up for the sake of it. It was pretty obvious to me that the batteries and the base of the driver's bum needed to be 100mm or less - so design for 95mm so with some tolerance built in. Go the safer side of the limit - in this case, lower to reduce the height of the CoG.

If there are things that aren't obvious then email admin, for instance we use a horn that has its own battery and this isn't covered in the rules but a quick email and we were ok.

I don't know why there is a ground clearance rule - if the batteries and driver's bum are 100mm or less from the road, there should be an advisory lower ground clearance limit (have you seen the state of Brian's undertray?!) but no rule. We use 1.5mm ally sheet as our seat and floor combined, so we could have a ground clearance of 98mm...

Although you may see F1 pushing rules right to their limits, they all pass the safety rules otherwise they wouldn't be allowed to race.

We have just introduced colour coded standards (rules) at work: red you must comply with, yellow you really should comply with and green you should comply with. Typically reds are safety or legal requirements, yellows are for efficiency or cost and greens are good practice. That's not to say you can just break a yellow or green rule - you must justify why you are, agree it with a suitably senior engineer and record it officially. In Greenpower's case, most rules are effectively red as they're either safety or racing rules - you wouldn't want people at an unfair advantage now would you?!? Some could be yellow as my ground clearance example earlier.

A few weeks ago I asked Admin about the ground clearance rule and was told that it was in place because of some very bumpy tracks/pit lanes, I suppose if you're doing 5mph in the pits and have very low ground clearance there's a slight chance of getting hung up and causing an obstruction.

I think more to the point, its the timing line you need to be careful of. You don't want to do this () now do you

Nor do you really want the race to be suspended/shortened/cancelled because your car has taken out the timing system.

-Luke

Huh, didn't realise you could post Youtube videos straight to the forum.. I like it. Nice work admin.

-Luke

I am reluctantly going to make the seat "top" 100mm from the ground, batteries are 105-110mm that will have to do.
A.

peterF, there is a lower ground clearance minimum stated in the 2013 rules and it's 30mm, the same as for 2012.

CC

To me the whole issue is one of safety. With narrow track cars which seem to be all the rage (Rotary Racer, the Seaford cars, Zebedee etc.) combining the narrow track with a high seat height and battery location means that the chances of rolling are pretty high. Maybe not in normal driving but when suddenly changing direction to avoid another car (as an example) then narrow cars with a high CoG can go over. Probably this tendency will also be worse on narrow cars with a short wheelbase and batteries/motor/driver located outside the wheelbase (high polar moment of inertia and all that).

The aero benefits of running high make sense but surely the cars need to be safe (i.e. not likely to fall over when the driver sneezes the wrong way) first THEN worry about aero efficiency.

OK I have the seast top at 100mm above ground, ground clearance will be around 45mm because of two alloy cross members mounted under the chassis. This is the problem of modifying a car rather than a new design.
I too cannot see if would be sensible to mount batteries and seat at much higher than 130mm, my problems have been the chassis design on this car and the fact that the body on our other car is 28mm thick so getting adequate ground clearance which I thought was 40mm has been difficult.
A.

Wooly, unfortunately this rule does not reduce the rolling possibility for particular designs (does probably end up making most ok though) and does restrict cars designs severely. Only a tilt angle test to a reasonable defined angle would achieve that goal.

One thing on this that I am a little concerned about is to make sure the drivers back is well protected. With trying to get the drivers bottom at 100mm above the ground and with a laid out driver position, there may be the difficulty in making sure the drivers delicate back is well protected by the cars bodywork under their back or the temptation to ignore this. I would suggest that the rules should apply the same regulations for the cars sides to this area as well. ie protective sheet and 25mm of foam or a seat that provides sufficient protection.

Absolutely spot on regulation with 500mm track ,

But a lot of cars that cannot meet that reg AND have shown no stability problems whatsoever due to a wider track are going to be scrapped if they cannot be modified and I suspect a fair few will fall into this category , This may be the end of some good teams which we do not want !!
The solution would be to allow a car with more than 500 mm track a bit more seat height ,say the same percent increase of track could apply to the min height , for example a car with 600mm track ( 20% more ) would be allowed a seat height of 120mm . this would allow teams to lower the seat as much as the chassis will allow and then extend the track to match . It would not get all the "non compliant " cars back into compitition but would be a safe way to help a lot of them .,

Personally I think the rules changing and requiring car modifications or new cars is a good thing. This is an engineering challenge after all, and its with the modifications and car design/builds where most of the engineering challenge happens. It also adds more interest in the racing side with different teams/cars taking the lead.

Actually RR8's track is 600mm and its drivers bottom height is about 120mm (its batteries are a bit higher though). Considering our experience with RR8, I think, as heights are being used to increase stability, then 100mm seat height for a 600mm track car is roughly about right for a car with a low driver and all other weights low down.

Note that RR8's current roll angle is about 47 degrees. If we lowered it by 20mm and lowered the batteries to match the new 2013 regs it would have a roll angle of about: 49 degrees.
However if we also reduced its track to 500mm its roll angle would be about 43 degrees. I and others would consider a roll angle of 47 degrees to be a minimum ...
And this is for a pretty flat driver position and other weights low down (motor etc). if the driver is sitting up more or some of the cars weight is higher then the roll angle gets less and the chance of tipping becomes more likely. With a roll angle of about 39 degrees (easily possible with the regs) with the same tyres that RR8 uses on a normal track the car will roll 100% of the time with hard lock applied ... Other tyre/ track combinations may have better grip, in this case the 100% of the time roll angle would be higher than 39 degrees...

I would strongly suggest that if any team is intending to design/build a car with, lets say less than 700mm track, they should calculate its roll angle before building and and later measure the actual cars tilt angle as just relying on the regs heights will not be good enough. It is also a useful exercise for the younger members to show an aspect of how engineers would use science and maths in the design process.
There is some info and a calculator at:

http://www.greenpower.beamweb.co.uk/files/TechnicalInfo/CarStability.html

Just backing up what Terry says.
Obey the regs because otherwise the scrutes won't let you race, but add 10 seconds to your car build time to measure the tipping angle on your car. just do it - do it because your own kids' safety is at stake.
I'd put a hard limit at 45degrees with 47+ preferred

At the end of the 2012 regulations document, it states that for 2013 there will be a 'maximum ground clearance of 70mm'. Maximum ground clearance is a difficult concept to get your head around, so we asked admin how this would be defined.

It seems that the maximum height will be defined along the entire length of the car, and therefore presumably all of the car that can be viewed from below. This will rule out of competition Rotary Racer (front and back both higher than 70mm), Zebedee (front, back, and centre), and every unmodified kit car (underneath motor, seat, and overhanging sides).

In this case it would seem that the definition of 'floor' is the critical issue - would a definition of 'reference plane' as seen in the F1 technical regulations be more appropriate? Surely the new regulation is a draconian measure to implement given its negative effects on aerodynamics, and minimal effects on roll angle since we have a 100mm limit on batteries and driver anyway?

Apologies if i'm wrong.

Thanks, Alex (PGR01 is the car name.)

I'm very glad I read this, I'm close to starting the building of my mould for a new car and if this is the final ruling on the case then I need to redesign the whole thing.

Also I can't see how RR and Zebedee could ever be told they can no longer race, they are 2 of the best cars around!

Alex, I've just downloaded the 2012 regs, including the proposals for 2013 and can't see any mention of 70mm ground clearance, just that the driver's seat and batteries have to be less than 100mm from the ground.

We discussed this extensively with Greenpower before building Bernard. the wording was a bit grey and it took a bit of clarification, but we were assured Bernard would be fine. It initially seemed to me that only flat bottomed cars would be allowed but this is not how the rules were intended to be interpreted,

Please accept my sincere apologies - it turns out I was wrong. I have an older copy of the 2012 regs and they have been changed since I downloaded them.

Sorry for the heartache caused.

Something that helps stability in the real world is anti-dive geometry, where the C of G is below the suspension pickup points on the chassis. This limits weight transfer under cornering and acceleration so that there is less risk of rolling if you hit a pothole or ditch. Regardless of the roll angle though, the roll bar and harness need to be the primary consideration in the car because in a race anything can happen.

Alex

This is becoming a bit of an " old chestnut " We are ALL in agreement that preventing a roll or similar incident is something that well thought out ,easily interpreted regulations can deal ,with but how do we achieve this ?
A reference plane is an excellent idea when framing geometric limits to bodywork , weight distribution , compulsory safety items and the like , the great difficulty is proper interpretation by teams and scrutineers . You always get a few anomalies , for example - I was present at the recent Mallory test and saw a car pass scrutineering with a blatant failure to comply with the roll hoop regs ( drivers helmet about 25mm above hoop !) another car failed the brake test because it had been fitted with an anti lock brake system that can only work on a moving car , these are two examples of poor scrutineering and poor regulational interpretation respectively .
If a reference plane was introduced it could be located at a virtual position - say 250 mm above ground level - a virtual"plimsol" line if you like. ALL other dimensions could be taken above or below this . Scrutineers could have a simple horizontal gauge with a spirit level and 3 points of contact with the ground to keep it 250 mm high and parallel .
The very great point is this- the regulations should have nothing open to interpretation at all . An excellent example are the Le mans regulations for LMP cars enforced by the "ACO" , it is very explicit and clear , whereas the FIA framed regs for single seater racing offer a great deal of " I wonder If? " speculative interpretation .
To cut a long post short perhaps a " working committee " with at least one qualified motorsport based engineer on board could be set up to facilitate this ?

the problem with your suggestion is that any "reference plane" would have to be transported to every race and in order to scrutineer all cars in a timely fashion for some races up to 6 would be needed which would take up a lot of van space that is hard to come by! In terms of drivers being too tall for the roll bar this is very hard to scrutineer as we are often told that the person sat in the car is the tallest only to find out later that they aren't. Next we try to keep rules that are paramount to safety very specific so the driver is always safe however there may be some others that are left to interpretation because this is an engineering challenge and teams often come up with really good ways of satisfying rules that we would never have thought about which is really what makes Greenpower so special. Finally there is a group that looks at the rules with engineers and ex competitors. Hope this helps with some of your issues.

Josh

Having scrutineered myself I can see where you are coming from JD210 but the car in question at Mallory went out several times and NONE of the drivers were within the rollbar regs to be fair.

Tigris - we were the car (Bernard) that had its anti-lock brake system failed. We developed the idea with help of an amazing guy who works at a bike shop which advises and supplies the Polish Olympic team amongst others. We knew it was bit 'grey' in a static test but the system was optmised for a moving car. We replaced the special adjusters with standard ones and passed scrutineering only for our first driver to do a 180 after half a lap when he grabbed a handful to avoid a slow car that was weaving about a bit.

To be fair Jeremy was very open to our ideas and hopefully it will return at a later time when we can demonstarte it to him in some way.

A fantastic example of something we would never have thought of! I wouldn't put it on because it sounds heavy ;) but alas my Greenpower car building days are over for the time being at least. I look forward to seeing Bernard sometime this season!

Anti-dive geometry does what it says on the tin - the weight transfer is still the same, just the body doesn't dive. For those cars that use suspension, too much anti-dive takes the loads out of the suspension springs and into the suspension linkages, so they need to be designed specifically for them. This isn't too much of an issue for the 98% of cars that don't use suspension (which are therefore effectively they're 100% anti-dive, anti-squat and anti-roll) as the relative braking and accelerating forces are small. Where the brakes are determines how the forces are applied to the chassis but does not change their weight transfer. See Wikipedia. Work it through, and you'll have all the reasons you need not to use rear brakes.

With the anti-lock example, fair play to the team that use it but we were hit during practice at the final and if our driver hadn't had the brakes on while stationary then we'd have shot off into the marshal's legs.

Here's an offer to the Greenpower team: I'll design, build (or at least arrange the build) and fund a tilt testing table that can fit in as small as space as I can get it in. It's the only fair test for all of these points, and you could simplify (or even scrap) a lot of the rules. It could also be used to test the brakes if you wanted too...

Peter F - the brakes work fine at standstill, just not quite enough to pass the 'push' test in scrutineering. I would be surprised if the brakes on any Greenpower car would be sufficient to prevent a car moving in the scenario you describedue to the tiny contact area of the tyres - the brakes may well prevent the wheel from turning but unless you use nice wide grippy tyres it will make no difference. And that would defeat the object in en electric endurance event. The only exception I can think is of a very slow speed incident, in which case our system works fine.

It would take too long to explain exactly how it works but it doesn't reduce braking efficiency in any way. In fact the opposite, it allows the driver to apply more braking force whilst greatly reducing the chance of locking a wheel. In the dry its not so much of an issue but we think it is a major safety benefit in wet conditions and worth the extra weight.

My 2 pence worth....
there's a lot of good points raised above - yes zebedee will no longer be compliant, this is good because it has spurred us on to make the new car (we had messed around for a year...). And the competition is actually about building cars, the racing is just a bit of fun ;^)
I have always been in favour of tilt testing for stability and brakes, and, like PeterF offered to supply hardware (I proposed a tilting trailer because that could also be used for recovery at races and would add to the transport capability of the greenpower vans rather than taking up room....) Old story, I've accepted it's never going to happen.
I'm looking forward to seeing Bernard's ABS - fantastic ambition there guys - excellent!

Hi JD210
A reference plane is totally imaginary it is purely a reference point to which all other measurements are taken . you would only need the scrutineers to have their straight stick held above the ground to the required hieght .
The main benefit is wording the regs for example - no bodywork shall extend more than 230 mm below the reference plane - or - the drivers seat shall be no more than 190 mm below the reference plane -
very simple to understand and free for curved or flat bottomed cars as required.
Hi TRS
it always made me wonder why you would brake test a stationary car , I know its simple but you could push a LMP car with carbon carbon brakes around a paddock with the brake pedal to the floor ! But wait until there is a bit of energy in the system !

Hi Bob
The ABS system on Bernard is entirely mechanical and weighs in at under 600g fitted . It works by pulsing the hydraulics - just like a road car brakes , I use a simple resonant "system" to achieve this but i am not saying any more sorry . By the way it only works on a moving car and in the dry it only adds weight , shame we couldn't try it at silverstone and were prevented from using it at the initially wet test at mallory ( absolutely correct within the wording of the regs by the way - no gripes with Scrutie or Greenpower )

@BobC - Such a shame to hear Zebedee will no longer be compliant! I've always enjoyed seeing it go around the track, truly one of, if not the best, car to have been built in my, and I'm sure others, opinion. If its ok to ask, what makes it no longer compliant? I'm trying to finalise a design for moulding which needs to get done pretty quick and just want to know what will be allowed next year and whats being rejected. I take the rules as batteries and seat no higher than 100mm of the ground but possible issues which curved floors is making me think I need a completely flat floor.
Something I've been thinking, what would be classes as the floor, for example my idea had a similar front end to RR which makes the floor look as though it goes right to the very front however wheres the cut off point for the nose cone as thats surely no longer the floor. Is it at that point that there must be a certain hight from the floor or the very tip of the nose?

Kind of you to say that Dan, - it's all just too high up. To make it compliant we'd have to move the wheels up on the chassis - easy enough to do, but then the bodywork is all totally bazookered - and alterations to that are big jobs. And the car is old now, too heavy at low power levels and needing more and more effort to keep it running sweet. And like I said, the point of the whole party is designing/building the cars, so we move on! Nice to retire the old girl while she's still reasonably hot & not smashed up too! We'll keep Brian running (even though its got considerably more mileage - probably pushing 5000 in competition by now !) as it's such a good base for trying things and training. (Brian's a bit of a favourite with everybody - it really would be a wrench to retire Bri.... Zeb is faster but nowhere near as nice to drive)

Fair enough, a huge shame none the less, but I cant wait to see your new car. Your right about Brian, it always does give me a smile seeing it go around.

PeterF, as you've dragged up the same old chestnut again with tilt tables for stability, nothing as complicated as that is needed. All that is needed is an angle measurer with spirit level something like:

http://www.dm-tools.co.uk/product.php/site/froogle/sn/FAIRLANGLE

This or something cheaper, perhaps with a bit of wood to place across a car, would do. Just get a scruitineer to tilt the car to balance with driver in (holding onto the roll bar) and measure the angle. About 20 seconds done at the MOT test. This really measures the stability. Much, much better and quicker than measuring heights of things and measures what is actually needed and has no complicated rule interpretation issues. This method also offers considerably more scope for teams to properly engineer their car in a multitude of different ways. BobC, I and others have talked about this quite a bit in the forums and to GP but GP are not interested for some reason.

I'm with BobC, on the rule changes meaning cars can no longer race (without modifications) and thus promoting new design/builds. In fact maybe it would be good to have a major change every 4 years or so to keep things getting stale ? After we have got used to the new batteries, we could go back to streamliners again with just two sets of batteries (or even 1) for a bit, that would change things a bit :)

Sorry Dan, BobC. I had an old copy of the regs and they have been changed, so Zebedee, RR etc. can still compete. Damn...

I'll back up Dan that Zeb is probably the best F24/24+ car ever built. Anyway - did I hear a rumour of a Dougal coming along any time soon, (I guess it couldn't be Ermintrude), because that is a car I'd like to see...

Good luck with the tipping table idea - that is something I think we need to improve safety. However, we ought to be careful to not take the emphasis of a proper roll bar, as any car can turn over: the Titanic sank, didn't it.

Alex

Just seen Terry's post - i'm all for going back to closed tops. We need a shake up now and again, and after 4 years or so most of the cars are old anyway. It also means that everyone who joins a year 8-11 school team gets to design and build a new car at some stage or another - and that's the fun bit if you ask me.

Personally I can't see anything outlawing a curved floor in the current regs long term development plan.

"The major changes for 2013 will focus on two main areas:
Vehicle Stability:
‐ The minimum ground clearance will remain at 30mm. The base of the driver’s seat and batteries
will be no greater than 100mm from ground level."

We're just starting our RLR2 build, and we should be able to keep RLR1 running on smaller 16inch wheels - an easy solution for the 'wheels out' designs ;).

I agree changing regulations keeps things fresh, and building a car in school with the students is the core of the project. It's a shame that some teams rock up with cars built by professional engineers that have never even seen the school premises during the build...

Also, I've supported the tilt test in the past and agree it's the solution that ensures the objective of stability, without stifling creativity...

Ben

Its not the use of a curve floor that I think could be outlawed, its if the curve goes higher than 100mm from the ground, will that be outlawed? Rotary Racer is the perfect example, will it be allowed to race as although the driver looks to be sitting less than 100mm from the floor the front and back curve up to higher than 100mm. This is what I want Greenpower to finalise as depending on what they rule will be a major factor in the design of a car.

Dan, does it say that a floor higher than 100mm is not allowed? The rules are there to be interpreted!

True, but it also doesn't say it is allowed, and with the rules not fully published yet its a worry when designing a new car, and waiting until September for them to be published is too long to wait. Hopefully Greenpower can give a ruling on it soon.

through my interpretation it would be that the "solid floor under the whole of the driver" that is currently required is what would have to be no more than 100mm from the ground, any other bodywork is fair game

I agree with Ben, the rule is there to lower the CofG using heights and the driver is probably the heaviest item so should be kept low down. Thus assuming this is the spirit of the rule, the rest of the floors height is thus not that important so I would not have thought that GP would have any issues with any shape cars underside as long as the drivers bottom and batteries are low enough. I would send an email to Jeremy to confirm for your peace of mind.

Actually the drivers bottom is at 120mm and the batteries are higher in RR8, so it won't match the rules as is. We could lower it to match, but are making a new car as we have quite a few new team members who haven't built a car. However, at the current rate of progress we may have to mod RR8 :)

Josh, if the rule is "solid floor under the whole of the driver" should be no more than 100mm above the ground, that would be an issue to us. With 2m drivers, that would more or less dictate a flat floor ....
I hope that is not the case ...

I'm with Terry on this one, as I'm sure is clear from all my previous posts.
I hope it doesn't mean flat floors, though I worry that it does...
Hopefully a ruling will be published soon.

i would agree that it could pose problems however if this isn't the case i don't see how it would reduce the CofG as i imagine my legs weigh more than a pair of batteries and i'm not participially tall or weigh very much, i imagine it will need to be discussed and will try to talk to Jeremy once my exams have finished on Friday.

If you mean a flat bottom to the car then don't worry. See my previous post. We have been there and done that regards the regs. Look at Bernards undercarriage and its not flat and won't be a problem. We checked and checked again as Bernard has about 600 quids worth of carbon and epoxy so we couldn't afford to make it then make it again to a new design.