hood problem

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hood problem

hood problem

Author	Message
Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Warren (Staff) - 6/9/2020 10:24:10 AM Every gram counts guys. LOL. Still, 6kg is a massive saving over the OEM steel version. But you could certainly loose more if you wanted it really light. Absolutely! An old race car builder back in the day told that that once you had removed the easy weight, in order to remove the next lb (told you it was a while back :-) ) you have to remove an ounce from 16 places. However, you can go too light, compromising structural rigidity, so I have to keep reining myself in :-) Edited 5 Years Ago by Steve Broad
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beliblisk	b beliblisk posted 5 Years Ago HOT Post Details
b Group: Forum Members Posts: 53, Visits: 2.8K	Well OEM alu sits at 10.4kg. Top half weights 2.5kg and its 1mm thick. This bonnet is quite big as i just managed to get 1.5m cf cloth to fit OEM closing mechanisms will be used and with these you really need to push a bit on the hood (i imagine something much thinner would just warp to much). Ill post more pics (including guns ) once i try to correct "island" Edited 5 Years Ago by beliblisk
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x beliblisk - 6/9/2020 11:24:29 AM Well OEM alu sits at 10.4kg. Top half weights 2.5kg and its 1mm thick. This bonnet is quite big as i just managed to get 1.5m cf cloth to fit OEM closing mechanisms will be used and with these you really need to push a bit on the hood (i imagine something much thinner would just warp to much). Ill post more pics (including guns ) once i try to correct "island" Agreed, there are considerations other than simply weight that have to be taken into account. My Elan door weighs 2.6kg including polycarbonate window, hinges, locks and handles. However, I added a couple of extra layers (door is two layers of 200gsm prepreg) in the area where it will be pushed to close and where the hinges attach.
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Hanaldo	Hanaldo posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Nah, weight is king, screw the rest 😉 Haha to be fair, I was mostly just jibing. Bonnets can be difficult to get a lot of weight out of, they are big flat panels. The rear clam I posted a photo of has so much geometry that even a single layer of 200g would be quite rigid. And for a vehicle needing OEM fitment solutions with hinges and the latch, you're pretty restricted with what you can do. So 6kg isn't bad at all. I dare-say you could get it down to ~4.5-5kg, but there's no real point.
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Hanaldo - 6/10/2020 3:26:14 AM Nah, weight is king, screw the rest 😉 Haha to be fair, I was mostly just jibing. Bonnets can be difficult to get a lot of weight out of, they are big flat panels. The rear clam I posted a photo of has so much geometry that even a single layer of 200g would be quite rigid. And for a vehicle needing OEM fitment solutions with hinges and the latch, you're pretty restricted with what you can do. So 6kg isn't bad at all. I dare-say you could get it down to ~4.5-5kg, but there's no real point. I experimented, making two small curved panels using one and two layers of 200gsm prepreg. I would have loved to have used one layer but this was just too flimsy and see though! I disagree with your comment 'no real point' :-) If you are making a part to reduce weight go big or go home! I would argue that lightweight parts have no real point on street only cars other than for 'street cred', whatever that is. But for that, you might as well skin or wrap :-) For track cars, if looking for lightweight you have to be serious about it or you are wasting your money, IMO. But then, I am anal about weight :-) This is two layers with a 20mm overlap of the 250mm strips of 200gsm it is made from. Layers are at 90 deg to each other.
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	90°? what is the point of that?
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x oekmont - 6/10/2020 10:39:18 AM 90°? what is the point of that? Placing the overlaps at 90 degrees so what little reinforcement they gave was spread in both directions. Seemed like a good idea at the time. Lining them up on top of each other may have been better but I am not making another one to find out :-)
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	You are talking about regular twill, or am I wrong? 0° or 90° should not be a significant difference.
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x oekmont - 6/10/2020 12:28:15 PM You are talking about regular twill, or am I wrong? 0° or 90° should not be a significant difference. It was nothing to do with the twill. it was the number of layers at the joints. Where the strips overlapped there was an extra layer. If I overlaid the two layers at the same place there would be 4 layers instead of 2, making a stiffer strip. However, I decided to rotate the second layer so I had strips of 3 layers 250mm apart forming squares as opposed to strips of 4 layers 250mm apart running in one direction only. Does that make sense? :-) I have no idea which method would be stiffer, but the difference would be marginal.
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