Ultimate Seven Product
Discussion
Equus said:
The Elise chassis is pretty much identical in weight to the Caterham spaceframe (lighter by about 4kg, I think), and the retail price for a replacement chassis appears to be near-as-makes-no-difference the same (Elise chassis is a mere £75 cheaper, from a quick Google - still, £75 per car on 600 cars per year would pay someone's wages).
I accept that the designs are not directly comparable, of course, but that suggests you might be looking for about the same weight advantage as Caterham's butted tube chassis (for which they were suggesting a £1K-£2K premium on cost, don't forget), and about three times the stiffness, with no price premium. With a lighter car overall, like the Caterham, though, you might be able to reduce the size/thickness of the aluminium extrusions to gain a bigger weight advantage.
As an interesting comparison, Pilbeam had a carbon fibre direct replacement for the Elise chassis designed that saved approximately another 26kg (though they didn't declare the stiffness, so I don't know how much better it was in that respect, and doubtless the price was a bit scary as it was a conventional pre-preg tub). As I said, there are cheaper ways to do CF than a conventional pre-preg tub, though.
Where are you getting the stiffness figures from for the CSR, by the way (and what absolute figures do you have for the standard and CSR chassis)?
I'm working on circa. 2,500lb.ft/degree for the standard chassis, fully panelled but uncaged, but the best information I have is that the CSR whilst better, isn't anything like twice as stiff as the standard item.. the figures I've heard quoted by the company suggest 'only' a 25% improvement.
Re CSR stiffness, the claim is from Caterham themselves though I have seen no figures. I believe some of the improvement has been fed into later s3/5 chassis. I accept that the designs are not directly comparable, of course, but that suggests you might be looking for about the same weight advantage as Caterham's butted tube chassis (for which they were suggesting a £1K-£2K premium on cost, don't forget), and about three times the stiffness, with no price premium. With a lighter car overall, like the Caterham, though, you might be able to reduce the size/thickness of the aluminium extrusions to gain a bigger weight advantage.
As an interesting comparison, Pilbeam had a carbon fibre direct replacement for the Elise chassis designed that saved approximately another 26kg (though they didn't declare the stiffness, so I don't know how much better it was in that respect, and doubtless the price was a bit scary as it was a conventional pre-preg tub). As I said, there are cheaper ways to do CF than a conventional pre-preg tub, though.
Where are you getting the stiffness figures from for the CSR, by the way (and what absolute figures do you have for the standard and CSR chassis)?
I'm working on circa. 2,500lb.ft/degree for the standard chassis, fully panelled but uncaged, but the best information I have is that the CSR whilst better, isn't anything like twice as stiff as the standard item.. the figures I've heard quoted by the company suggest 'only' a 25% improvement.
The big problem (Re alternatives) is that aluminium body contributes significantly to chassis stiffness but adds relatively little weight. As the S4 and Westies show using fibreglass costs weight.
bcr5784 said:
Re CSR stiffness, the claim is from Caterham themselves though I have seen no figures.
Claimed where?! The reason I ask is that I've been in NVN seminars where they've used the 25% figure, straight from the horse's mouth. I have it in my own notes (though I've seen it used in the press, too)!
...and 100% increase in stiffness on any visually similar spaceframe is frankly very difficult to believe.
I'd be more inclined to believe that the 100% figure is mis-reporting by journos, unless it can be directly ascribed to a Caterham engineer or direct press release.
Actual chassis stiffness figures are next to impossible to get hold of, unless you physically test a chassis yourself, of course - they know that any spaceframe will look dismal against something like the Elise. It's sometimes interesting what gets let slip verbally, in seminars, though.. often when they'll quote a figure for the improvement, then later quote a percentage figure so that you can work it back!
Here http://www.autocar.co.uk/car-review/caterham/seven... though that's not the only place I have seen it. What I read was that 25% was initially achieved, but the aim was to make the effect of a cage undetectable. And they ultimately made it 100% stiffer to achieve that.
Hmm... so according to that, we're not talking about an increase in stiffness of 100% over the S3.
Elsewhere in the article they're actually suggesting that it is infinitely stiffer than the S3, in fact, but I think we can probably discount that as Hyperbole.
I think I'll stick to my own sources, if you don't mind!
Autocar magazine said:
I drove a development CSR race car last November... Since then the car has gained a colossal 100 per cent extra torsional stiffness...
The development car chassis must have been stuck together with chewing gum, if that's to be believed (though personally, I rank Autocar's credibility as about on par with the Sunday Sport and the National Enquirer, these days), but either way they're not claiming a 100% increase in stiffness over the 'normal' Seven. Elsewhere in the article they're actually suggesting that it is infinitely stiffer than the S3, in fact, but I think we can probably discount that as Hyperbole.
I think I'll stick to my own sources, if you don't mind!
Personally, I think aero improvements are the last thing a Seven needs. The owners love the appearance of the Seven.
A composite chassis even with only marginal gains in weight and torsional rigidity over a standard chassis would fix the cars Achilles heal which is extremely poor corrosion resistance. I love driving my Seven, but the more miles it does, the more chipped and dented it is, and I daren't drive it on salty roads despite using loads of Dinitrol when I built it (unlike the factory
).
A composite chassis even with only marginal gains in weight and torsional rigidity over a standard chassis would fix the cars Achilles heal which is extremely poor corrosion resistance. I love driving my Seven, but the more miles it does, the more chipped and dented it is, and I daren't drive it on salty roads despite using loads of Dinitrol when I built it (unlike the factory
).Corrosion resistance is a very fair point... though you'd have to be careful about the design as a car with a CF tub can be equally prone to corrosion if you get the detailing wrong, due to galvanic reaction between the CF and metal hardpoints/brackets.
Personally, I'd focus on both aero and weight,
I agree that aerodynamics is an easy win, though perhaps it's not so easy to promote the benefits for marketing purposes (at least without inadvertently highlighting just how terrible the Seven is in this respect). With weight, it would be easy to justify the 'ultimate' tag by producing the lightest production sportscar in the world. And as a certain Mr Chapman pointed out, weight pays dividends everywhere, whereas aerodynamics only start to make big differences in the upper speed range.
The other thing with weight is that they need to stop the rot before it sets in too far. The old K-series superlights were quoted at 486kg, if my memory serves correctly. Disregarding the pedestrian Seven 160, the lightest car in their current range is quoted as 54kg heavier... that's like having a permanently installed girlfriend in the passenger seat (albeit without the whining).
Since Caterham have built a business on parasitising Lotus' reputation, perhaps they might draw some inspiration from other Lotus sports racers and/or the early concepts work that Lotus did on the 'step-in car' that ultimately grew doors and became the Elise, and go mid-engined:
Lotus couldn't make such a minimalist mid-engined car work because they had to comply with full EU Type Approval, but Caterham only has IVA or LVTA to deal with, so they can do something more extreme.
Personally, I'd focus on both aero and weight,
I agree that aerodynamics is an easy win, though perhaps it's not so easy to promote the benefits for marketing purposes (at least without inadvertently highlighting just how terrible the Seven is in this respect). With weight, it would be easy to justify the 'ultimate' tag by producing the lightest production sportscar in the world. And as a certain Mr Chapman pointed out, weight pays dividends everywhere, whereas aerodynamics only start to make big differences in the upper speed range.
The other thing with weight is that they need to stop the rot before it sets in too far. The old K-series superlights were quoted at 486kg, if my memory serves correctly. Disregarding the pedestrian Seven 160, the lightest car in their current range is quoted as 54kg heavier... that's like having a permanently installed girlfriend in the passenger seat (albeit without the whining).
Since Caterham have built a business on parasitising Lotus' reputation, perhaps they might draw some inspiration from other Lotus sports racers and/or the early concepts work that Lotus did on the 'step-in car' that ultimately grew doors and became the Elise, and go mid-engined:
Lotus couldn't make such a minimalist mid-engined car work because they had to comply with full EU Type Approval, but Caterham only has IVA or LVTA to deal with, so they can do something more extreme.
I think we are missing the point; despite many attempts to diversify Caterham has signally failed to do so. Unless it can design , develop and build a product which is entirely novel in concept and execution it is swimming with the sharks who already compete in the extreme lightweight track/ sports car like Zenos, Ariel and Radical. I can't see it beating them in the same market. I would far rather that they continued to evolve the Seven- and bolting them together properly , improving the customer experience etc would be a good start . The service I had from Caterham Midlands varied from extremely helpful to cynically shabby and I am sure Book aTrack will be working very hard on laying to rest that sort of reputation- and early signs are good .
coppice said:
I think we are missing the point; despite many attempts to diversify Caterham has signally failed to do so. Unless it can design , develop and build a product which is entirely novel in concept and execution it is swimming with the sharks who already compete in the extreme lightweight track/ sports car like Zenos, Ariel and Radical. I can't see it beating them in the same market.
I don't think Caterham are or should try compete head on with those cars. The 7 has just enough weather protection and luggage space to make a weekend away a practical proposition, they don't. The 7 is narrow, they aren't. Keep/enhance those advantages and there will continue to be a market. The next Elise could spoil the party but I doubt it will.
coppice said:
...despite many attempts to diversify Caterham has signally failed to do so.
I do agree: Caterham's track record with new designs is so bad it would be comical if it weren't so tragic. But as per my response to BurtBurt on the last page, if they simply give up and stick to the Seven, we have to accept that they will gradually wither away in the face of ever more diverse completion and changing legislation.
Equus said:
I do agree: Caterham's track record with new designs is so bad it would be comical if it weren't so tragic.
But as per my response to BurtBurt on the last page, if they simply give up and stick to the Seven, we have to accept that they will gradually wither away in the face of ever more diverse completion and changing legislation.
I'm not so sure, current (and no doubt future) legislation has lead cars further from the size and weight of the Seven and have made it stand out even more as an experience. The main worry Caterham have is that their current low volume approval exemptions might be taken away and force them to design a car that is much more mainstream and won't stand out as much. Fortunately, in the USA they have recently changed the rules to allow low volume manufacture, and this has to be encouraging from the country that got so close to banning open cars in the 70s they gave us the TR7 coupe.But as per my response to BurtBurt on the last page, if they simply give up and stick to the Seven, we have to accept that they will gradually wither away in the face of ever more diverse completion and changing legislation.
downsman said:
I'm not so sure, current (and no doubt future) legislation has lead cars further from the size and weight of the Seven and have made it stand out even more as an experience. The main worry Caterham have is that their current low volume approval exemptions might be taken away and force them to design a car that is much more mainstream and won't stand out as much.
I think there are two further, very major, potential issues that they need to plan for:1) Current Low Volume regulations are bound to be evolved and enhanced in the future, particularly with respect to safety and emissions efficiency (the latter I know for a fact they're working on right now). The current Seven, with its ultra-high drag bodywork and zero side or rear impact protection, is good at neither.
2) Give it another 10-15 years, and the petrol engine as a sole means of propulsion will be dead. It is likely that everything will be either electric, or hybrid.
Companies like Morgan, Westfield, Lotus and Zenos have recognised this, and I can tell you (from their activity with the NVN, if not from projects they've already publicised in the mainstream press) that they're all working flat-out to develop knowledge and working solutions in these areas.
I could be wrong, but the best evidence that I have for Caterham (again from both NVN-funded projects and mainstream press) is that just at the moment, they're sitting around with their thumb up their arse, whistling Dixie.
Pdelamare said:
It was about the 310 model, wasn't it?
No, surely not?Graham MacDonald said:
...our motorsport programme has revealed something that we genuinely think could result in the ultimate Seven product. The engineering guys are positively giddy about this...
Marketing hyperbole aside, can we seriously imagine he was talking about the 310?Gassing Station | Caterham | Top of Page | What's New | My Stuff