Big Brother Posted September 2, 2006 Share Posted September 2, 2006 Before we start...I'm not an engineer, I'm not a designer or a materials or stress expert! However, I'd be interested in hearing your comments on the design shown in the photos . I'm not knocking the builder (I've a huge amount of respect for people who take on this type of project) but I'm just a bit uncertain (concerned) about the design. It just doesn't look very robust ❗ Links copied from the "state of the kit car industry" thread on Chitchat. Photo 1 Photo 2 Photo 3 Photo 4 Photo 5 I think the car is a Robin Hood "Lightweight" sportscar. It seems the car has no real chassis and is made from ali sheet and ali box section that is pop riveted to the sheet metal. Comments please Link to comment Share on other sites More sharing options...
simonbell Posted September 2, 2006 Share Posted September 2, 2006 I had heard the story about this but those photos do concern me. I`m no engineer but surely mounting the diff between two sheets of ali isn`t the way to go We all know about the elise which is aluminium all glued together but when you see an elise tub it looks robust............ Hasn`t the ligtweight Robin Hood been turned away from an SVA test on account of the tester not being happy with the chassis? I`d be interested to hear the thoughts of those with an engineering background. Simon Bell - Caterham 7 Duratec R I`ve seen the future.....and it`s powered by duratec Check out the website here Link to comment Share on other sites More sharing options...
oilyhands Posted September 2, 2006 Share Posted September 2, 2006 The torque loads on the diff will make mincemeat out of the side panel sections. I have an early Robin Hood which was severely compromised in several areas, without revision the rear beam could easily fall off the car. Any sensible builder will attend to these areas. oily Link to comment Share on other sites More sharing options...
Big Brother Posted September 2, 2006 Author Share Posted September 2, 2006 It failed the SVA with the following structural issues FAILURE SECTION 5 A seat belt anchorage or the surrounding vehicle structure is of inadequate strength and likely to fail. (No box section in areas of seat belt mountings or associated component attachments, no triangulation or bracing of thin panels, pop rivets used near seat belt anchorage strengths.) FAILURE SECTION 15.1 When driven, the safe control of the vehicle is or is likely to be impaired due to design or construction feature or characteristic (Monocoque has absence of structural box section in construction) FAILURE SECTION 15.1 The vehicle structure is of inadequate strength and likely to fail prematurely. (vehicle construction not considered to withstand forces and vibration to which it is likely to be subjected to.) FAILURE SECTION 15.1 A suspension unit anchor, shackle or attachment bracket of inadequate strength and likely to fail prematurely. (All suspension components in box sections bonded and fixed with pop rivets and self tapping screws to main panels.) I feel really sorry for the guy who bought/built it. He's stuck in the middle between Robin Hood (who say they have had other cars of the same design passed) and the SVA (who will not pass the car - even if he takes it somewhere else to be tested) The original thread is here http://community.rhocar.org/index.php?showtopic=12786&st=0 Link to comment Share on other sites More sharing options...
Peter T Posted September 2, 2006 Share Posted September 2, 2006 Er what chassis? How can the front box sections transmit any load to well anywhere??? There seems to be some lattice work missing? Is this a demo/ show car only? R500 Mango Madness Link to comment Share on other sites More sharing options...
Big Brother Posted September 2, 2006 Author Share Posted September 2, 2006 Nope...its a current model http://www.robinhoodsportscars.com/kitrange.php From the thread it looks like RH have said the car is aimed at track work, however the build DVD has a large section about preparing the car for its SVA. The ownder of the car in question is under the impression that RHSC have already stated they have had one pass its SVA. It looks like a bulletin has been circulated to all SVA centres warning /informing them of the issues the car sufferes from. I really feel sorry for the owner. He has followed the build manual/DVD by the letter. I would be considering taking legal action against RHSC if I was in his position, as the completed kit is "not fit for purpose" Personally I think Robin Hood should take the car back and work throught the SVA fails at no cost to the owner. However from posts made on the other forum, it looks like they are proving very hard to get in touch with. Edited by - Se7en-Up! on 2 Sep 2006 10:50:53 Link to comment Share on other sites More sharing options...
Nigel Riches Posted September 2, 2006 Share Posted September 2, 2006 It'll certainly be a "lightweight" when the rear drive seperates from the rest of the car 😳 1982. 5 speed, clamshells. B.R.G / Ali. The True Colours. Link to comment Share on other sites More sharing options...
Foxy Smith Posted September 2, 2006 Share Posted September 2, 2006 Is the sheet material actually aluminium. I thought RHs were supposed to be stainless steel monocoques?? Still looks a tad insubstantial though. Aluminium is not a good material for coping with varying stresses, it has a nasty habit of failing without warning and without going beyong its elastic limit. Link to comment Share on other sites More sharing options...
Big Brother Posted September 2, 2006 Author Share Posted September 2, 2006 Robin Hood site says A combination of pre-folded and pre-punched aluminium panels together with 50mm box sections some are precisely punched at the ends to accept the wishbones Steve SE7EN-UP! The difference between ignorance and apathy? I don't know, and I couldn't care less! Link to comment Share on other sites More sharing options...
Rob Morris Posted September 3, 2006 Share Posted September 3, 2006 Would make a great little soap box for Goodwood me thinks 😬 Are they serious about putting an engine in it............! 😳 Even bigger problem is you can't extract Ali from the body with a magnet so he will be in casulty for a long time........assuming that it fails!!! Link to comment Share on other sites More sharing options...
susser Posted September 3, 2006 Share Posted September 3, 2006 I think/hope pic 2 and 3 show a bit of ally bolted to the diff and not the other way around. there isn't anything connecting the front suspension to the rest of the car. Where would you hang an engine ? maybe Rob's right. it is a soapbox. either way it looks scary. susser ( 1/2 🙆🏻d engineer) Link to comment Share on other sites More sharing options...
Graham Perry Posted September 3, 2006 Share Posted September 3, 2006 Where does the lengthways stiffness come from in the chassis between the wheels eg in the engine compartment ? There is a heavy engine that needs to sit in there, but I can't see where the metal is for it to sit on Link to comment Share on other sites More sharing options...
Graham Perry Posted September 3, 2006 Share Posted September 3, 2006 Ah, Susser beat me to it ........ Link to comment Share on other sites More sharing options...
Colin Mill Posted September 3, 2006 Share Posted September 3, 2006 If RHSC have done their job properly they will have a big stack of stress calculations and/or test results to back up their design and they should be able to produce those to support the guy's SVA application. If they have not done the sums or tests then they have been negligent. Although I'm not a stress engineer I have been involved with fitting met instrumentation to several aircraft and have thus spent some time crawling around inside airframes. I have to say that the photos here show none of the complexity that stressed skin airframes have to flow stresses into the structure. I just did a rough sum on some of the forces involved and at the point the tyres loose grip under acceleration the dif is trying to go round the driveshafts with a torque of about 1600Nm. Likewise under heavy braking the torque around the front axle will also be about 1600Nm (that's about a 13 stone person stood on the end of a 2m long lever) Edited by - Colin Mill on 3 Sep 2006 10:17:26 Link to comment Share on other sites More sharing options...
davef Posted September 3, 2006 Share Posted September 3, 2006 This came up on either the Cam7 or Sevens mailing list a couple of weeks ago. The concensus then was that the SVA inspector was right - the thing looks a death trap. The guys blog is here - there are some interesting photos on there of the construction. Dave Link to comment Share on other sites More sharing options...
timbo Posted September 3, 2006 Share Posted September 3, 2006 nahhh... I don't believe any of this thread... you guys are taking the piss... this is really an episode of 'Blue Peter' ... egg cartons & toilet rolls. Graham... my thoughts exactly... thats a Pinto going in there... *eek* *eek* SV 2.3 Duratec and for the last time, no it is not a truck Link to comment Share on other sites More sharing options...
Grubbster Posted September 3, 2006 Share Posted September 3, 2006 I've just had a trawl through the thread on RHOCaR, if it were my car I'd be pretty upset by now. Interesting that it is the Southampton SVA centre - the one CC don't even list in their documentation Apparantly notorious for not passing 7 esque cars, a lot of their work is dealing with grey/parallel imported cars so that is what they are best at I guess. Can't really comment on the RH car without looking at one in detail, but I must admit it looks flakey. Roadsport build photo's here Le Mans 2004 photo's here Link to comment Share on other sites More sharing options...
wag Posted September 3, 2006 Share Posted September 3, 2006 What do I know about car design? It seems to me that the box sections are too strong and stiff (but available off the shelf and easily riveted) whilst the ali panels are far too floppy. That combination of general floppyness and local stiffness is lousy engineering. Link to comment Share on other sites More sharing options...
elie boone Posted September 4, 2006 Share Posted September 4, 2006 Did'nt Chapman said that if a race car makes it out of the pitlane it's a good one. Times have changed since those days, like power outputs and tyres did. You really need to see the RH in real live to be able to judge it. Link to comment Share on other sites More sharing options...
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