Designing the composite hood

[ViperSmith]

http://www.compositesworld.com/articles/revisioning-the-viper-clamshell-hood-challenge

Good write up on challenges of the new clamshell

 

[Smog Dog]

Don't know how you found this article---Thanks! Interesting story with good pictures. No idea what the hood costs, but it can't be cheap!

Bill

 

[ViperSmith]

Ralph on Twitter! VPA reported it was listed around $3k a few months ago, would be impressive if it holds that price point.

 

[JETSTAR]

Very cool and expensive

 

[SRTviper]

3k is cheap for that hood. I expected it to be around 15k at least more than the plasan shelby kr hood.

 

[SRTviper]

ahhhh after reading the article that explains why it is so cheap. it is not 100% carbon fiber it says it is CFRP. I wonder if the roof and decklid are the same. What are the other panels made out of? Fiberglass? I know the doors are aluminum.

 

[Ev1E9]

Wasn't the GEN II clam-shell hood over $10k to replace?

 

[ACRucrazy]

Yes, but the technology was different 20 years ago.

 

[SRTviper]

Wasn't the GEN II clam-shell hood over $10k to replace?

According to Ralph in an interview it is more like 15k and could go higher as time goes on because you can't get them anymore. But yes this hood is 3k because it is CFRP and not full blown carbon fiber. I knew it didn't make sense for such a massive part of carbon fiber to be only 3k to replace and I thought it was weird when I looked under and it looks like the twill weave was glued on as an afterthought, though I guess it is because the hood is 2 pieces bonded together so one they make with visible weave and the other they make without it.

 

[ACRucrazy]

I brought up the CF hood topic here.

http://forums.viperclub.org/threads/667019-Sat-in-my-first-Stryker-Gen-V

 

[SnakeBitten]

Wait so its not full carbon fiber? I really hope the other carbon panels and carbon cross brace are full carbon. This is like having an aluminum finished accents on some other cars interior then finding out its plastic with an aluminum look finish. Kinda puts a damper on my view of the materials used but I guess it does keep cost down.

 

[ViperSmith]

Wait so its not full carbon fiber? I really hope the other carbon panels and carbon cross brace are full carbon. This is like having an aluminum finished accents on some other cars interior then finding out its plastic with an aluminum look finish. Kinda puts a damper on my view of the materials used but I guess it does keep cost down.

I need to reread it, it sounds like it is a composite CF outer shell, not 100% CF, which allows for cost reduction - but still gives you the CF benefits if being strong and light.

 

[SRTviper]

Wait so its not full carbon fiber? I really hope the other carbon panels and carbon cross brace are full carbon. This is like having an aluminum finished accents on some other cars interior then finding out its plastic with an aluminum look finish. Kinda puts a damper on my view of the materials used but I guess it does keep cost down.

The hood is at least CFRP so it is not full carbon fiber. Probably the roof and trunk are the same but they did it with an exposed weave on bottom.

 

[JETSTAR]

100% carbon fiber parts tend to have the weave print through the paint if you ever look at the race cars you will see what I am talking about. You can even see the weave pattern on my ZR1 . What I do when building a carbon fiber part that is going to be painted is make the first layer fiberglass to seal the carbon in and then 2 or 3 layers of carbon. For that hood to only weigh 36.5 lbs and still look that smooth is amazing.

Also there is no way they sell that hood for $3000.00 if I recall it was $3000.00 to switch one hood for another.
The ZR1 hood is $7000.00 and !/2 the size

 

[SRTviper]

100% carbon fiber parts tend to have the weave print through the paint if you ever look at the race cars you will see what I am talking about. You can even see the weave pattern on my ZR1 . What I do when building a carbon fiber part that is going to be painted is make the first layer fiberglass to seal the carbon in and then 2 or 3 layers of carbon. For that hood to only weigh 36.5 lbs and still look that smooth is amazing.

Also there is no way they sell that hood for $3000.00 if I recall it was $3000.00 to switch one hood for another.
The ZR1 hood is $7000.00 and !/2 the size

ZR1 hood I believe is full carbon fiber and not CFRP. I am not sure if it is fiberglass but you are right that painted parts with the weave will show through the paint over time. But I am pretty sure they can make just regular no weave carbon fiber which looks like the middle part of the hood. Which is just a grey greenish blob. I can't believe the hood weighs 36 pounds though when I lift it up and down it literally feels like 5-10 pounds tops.

 

[JETSTAR]

all carbon fiber has some kind of weave there is plain weave that works good on flat parts twill works best on curves also bi axial strong in one direction
the article said the hood weighed 36.5 lbs the ZR1 hood probably weighs 20 lbs

 

[SRTviper]

all carbon fiber has some kind of weave there is plain weave that works good on flat parts twill works best on curves also bi axial strong in one direction
the article said the hood weighed 36.5 lbs the ZR1 hood probably weighs 20 lbs

You sure? The video of the lexus LFA carbon fiber or koengisegg just shows them as a greenish black solid part with no twill weave (2x2) or single dot weave that ferrari and porsche uses (1x1). The carbon fiber driveshaft on my shelby is the same. You can see the strands of the carbon fiber as if it is hair almost but there is no weave like on the zr1 carbon fiber or porsche/ferrari carbon fiber.

 

[ACRucrazy]

100% carbon fiber parts tend to have the weave print through the paint if you ever look at the race cars you will see what I am talking about. You can even see the weave pattern on my ZR1 . What I do when building a carbon fiber part that is going to be painted is make the first layer fiberglass to seal the carbon in and then 2 or 3 layers of carbon. For that hood to only weigh 36.5 lbs and still look that smooth is amazing.

Also there is no way they sell that hood for $3000.00 if I recall it was $3000.00 to switch one hood for another.
The ZR1 hood is $7000.00 and !/2 the size

As for the weave goes, you can see the weave through the paint on my ACR's rear wing, you could also see the same on my '08 Aeros painted wing.

Now the new hoods, it's a $500 option for the GTS to be equipped with the SRT hood on the 2014s. It was confirmed earlier this year that the 2013 hoods were just over $3,000 from the dealer. Now if that price has changed at all since then I don't know.

As far as the ZR1 hood price goes, it has a WINDOW!

 

[SnakeEye]

Great article... the GTS/SRT clamshell hood is work of art and coming in at only 36.5 pounds for such a large panel is quite amazing... it seems to be a much stiffer structure than the GTS hood of yesteryears too.

 

[JETSTAR]

You sure? The video of the lexus LFA carbon fiber or koengisegg just shows them as a greenish black solid part with no twill weave (2x2) or single dot weave that ferrari and porsche uses (1x1). The carbon fiber driveshaft on my shelby is the same. You can see the strands of the carbon fiber as if it is hair almost but there is no weave like on the zr1 carbon fiber or porsche/ferrari carbon fiber.

Yes with out the weave there is no strength. your drive shaft is made of a single strand of carbon fiber crossing over and over it self creating its own form of weave
Carbon Fiber by itself is not really all that strong its only when you curve or put honeycomb in between two layers of carbon. It also depends on what you use for a matrix ( the resin that bonds the fibers together) temperature and strength properties.

 

[SRTviper]

Yes with out the weave there is no strength. your drive shaft is made of a single strand of carbon fiber crossing over and over it self creating its own form of weave
Carbon Fiber by itself is not really all that strong its only when you curve or put honeycomb in between two layers of carbon. It also depends on what you use for a matrix ( the resin that bonds the fibers together) temperature and strength properties.

http://www.youtube.com/watch?v=504I_hJDFck

Watch the video where they lay the carbon fiber. You see it has a twill weave and from the back you can see the tons of strands it has. Are you saying there is something else attached to that besides carbon fiber?


But in any case we see SRT cut corners and were playing it down that their "carbon fiber" pieces are really CFRP and that is why they are so cheap. Makes me really then start to wonder why this car is so much. I wonder if they cut corners on the interior leather as well.

 

[ViperSmith]

http://www.youtube.com/watch?v=504I_hJDFck

Watch the video where they lay the carbon fiber. You see it has a twill weave and from the back you can see the tons of strands it has. Are you saying there is something else attached to that besides carbon fiber?


But in any case we see SRT cut corners and were playing it down that their "carbon fiber" pieces are really CFRP and that is why they are so cheap. Makes me really then start to wonder why this car is so much. I wonder if they cut corners on the interior leather as well.

Cutting corners

lmao, lord.

 

[Pythonpete]

Doesn't CFRP mean Carbon Fiber Reinforced Polymer? Isn't that what Carbon Fiber is? Carbon Fiber is the Carbon weave material and when you add the resin it becomes CFRP. Am I missing something?

 

[SRTviper]

Cutting corners

lmao, lord.

Uh yea using CFRP is far cheaper and not as good as full blown 100% carbon fiber. That is called cutting corners. Especially when all advertisements make such a big deal out of the carbon fiber. The stingray for 50k is almost all CFRP and also from Plasan. And it also has the hood and roof in FULL carbon fiber not CFRP and the rest of the body panels are CFRP. Get over it the viper is over priced the more information we learn about it to more it points to that conclusion. you paid a huge premium to say you own a viper and not for the subsistence.

Doesn't CFRP mean Carbon Fiber Reinforced Polymer? Isn't that what Carbon Fiber is? Carbon Fiber is the Carbon weave material and when you add the resin it becomes CFRP. Am I missing something?

Carbon fiber reinforced plastic. So it is fiberglass with a couple layers of carbon fiber.

 

[Newport Viper]

Carbon-fiber-reinforced polymer, carbon-fiber-reinforced plastic or carbon-fiber reinforced thermoplastic (CFRP, CRP, CFRTP or often simply carbon fiber), is an extremely strong and light fiber-reinforced polymer which contains carbon fibers.


http://en.wikipedia.org/wiki/Carbon-fiber-reinforced_polymer

Carbon-fiber-reinforced polymer is used extensively in high-end automobile racing. The high cost of carbon fiber is mitigated by the material's unsurpassed strength-to-weight ratio, and low weight is essential for high-performance automobile racing. Racecar manufacturers have also developed methods to give carbon fiber pieces strength in a certain direction, making it strong in a load-bearing direction, but weak in directions where little or no load would be placed on the member. Conversely, manufacturers developed omnidirectional carbon fiber weaves that apply strength in all directions. This type of carbon fiber assembly is most widely used in the "safety cell" monocoque chassis assembly of high-performance racecars.
Many supercars over the past few decades have incorporated CFRP extensively in their manufacture, using it for their monocoque chassis as well as other components.

 

[JETSTAR]

If you open the hood and look at the intake NACA scoop you can see what the top part of the hood is made of and feel how thin it is. It is not plastic but some kind of fiberglass composite and the carbon fiber inner liner is 2 parts joined in the middle.
I will have to do some more research also there is no way that they can sell this hood for $3000.00 cant be done. I bet it is 15 to 20k

 

[Pythonpete]

RIF "Materials selection for this project drew from supplier input, Shinedling’s automotive experience, and the aerospace background of colleague Howard Coopmans, Viper project responsible, Street & Racing Technology. “We had a lightweight objective on a large part that had to be toolable,” notes Coopmans, who, as a former Boeing engineer, well understood strength and stone-chipping issues around such a large part and suggested a move to a tougher resin system in the prepreg. The team selected unidirectional prepreg supplied by Toray Composites America Inc. (Tacoma, Wash.) for the inner layers of all panels and the outer layer of Class A painted surfaces, and used 2x2 twill-weave fabrics for the face layers of polished/unpainted inner panels. Although they are technically not aerospace-grade materials, they are impregnated with G83C epoxy resin, optimized for strength, cost, and processability, and supplied at standard 186-g/m2 (5.49-oz/yd2) areal weights. Their greater ultimate strength permits production of thinner, lighter panels with minimal surface defects and high smoothness. They meet the team’s high aesthetic requirements for both painted hood outers and polished hood inners. The ply counts vary depending on panel and location but, typically, six layers are used on the outer panel (except in thicker load-bearing areas around latches and hinge) and feature up to 15 plies on sections of the inner panel. As designed, the outer panel has a nominal 1.2-mm (0.05-inch) wall thickness, while the inner panel’s thickness varies from 1.45 to 3.25 mm (0.06 to 0.13 inches) to satisfy global panel stiffness and slam/durability requirements while still minimizing assembly mass."

 

[JETSTAR]

http://www.youtube.com/watch?v=504I_hJDFck

Watch the video where they lay the carbon fiber. You see it has a twill weave and from the back you can see the tons of strands it has. Are you saying there is something else attached to that besides carbon fiber?


But in any case we see SRT cut corners and were playing it down that their "carbon fiber" pieces are really CFRP and that is why they are so cheap. Makes me really then start to wonder why this car is so much. I wonder if they cut corners on the interior leather as well.

Nice video but you can see what it takes to make even a small part and they just use a oven the Viper parts are done is a autoclave oven that puts a lot more pressure on the part during the cure process making them even stronger and lighter. They are not cutting corners it is probably more work to make the hood with a inner and outer shell than it would be just to make it one piece but the outer finish would not stay as nice for long

 

[SRTviper]

Nice video but you can see what it takes to make even a small part and they just use a oven the Viper parts are done is a autoclave oven that puts a lot more pressure on the part during the cure process making them even stronger and lighter. They are not cutting corners it is probably more work to make the hood with a inner and outer shell than it would be just to make it one piece but the outer finish would not stay as nice for long

Yea but do you see how the Agera in the unpainted form is all carbon fiber. Then they use the actual twill weave on the small parts? For the body parts which are not twill weave is that part plastic? I don't think so. I say CFRP is cutting corners because that is what they put on the stingray for 50k. So because the viper has 3 parts made out of this justifies such a high price for what? I'm starting to wonder where is the money going???? At this point the only thing exotic is the interior and the paint job. Though I'm hoping info doesn't come out to make those seem less than what they are.

And nothing on the viper is better than the agera. Christian is a pioneer in engineering no one can touch him in the automotive industry.

 

[VRYALT3R3D]

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