Advanced Metals Gaining Ground in Lightweight Vehicles

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Re: Citroens
cookiejar   7/29/2015 10:15:49 PM
I did own a Citroen DS and am still in love with it.

1.  It was a 1971 with a 95hp engine.  I didn't find it slow at all.  In fact my workmate owned a 1970 Cadillac Sedan de Ville and stoptlight drags to work were about 50/50.  It's the light weight that did the trick.  Once you got rolling on the highway, the very low drag really helped in passing.  Fuel economy easily beat the Volkswagen beetle.

2.  Beauty is in the eyes of the beholder.  The DS has been rated the most beautiful car of the 20th century by the association of automotive journalists.  True the 2CV was ugly, so Citroen also held the prize for the ugliest duckling on the road.  I loved the poster wth the Concord's nose down to the 2CV with the caption, "Some day mon cherrie, you too will be a swan."

3.  It was more roomy than my Buick Lucerne in leg room and headroom and could comfortably hold 3 adults in the rear seat, unlike the Lucerne's with its hard center armrest. 

4.  The ride was smooth and the handling with the Michelin AXS tires was incredible.  You didn't realize how well it handled because it was so well behaved.  I had a couple of Corvettes spin out trying to follow me on entrance ramps.

5.  Reliability for the 1971 was remakable, after all they had 17 years to get the bugs out. I compared my maintenance record to my sister's Datsun 510, known as a very reliable car.  It was less than 1/3 of the Datsun.  I got 187,000 trouble free miles from it.  You could take up the wear on the suspension ball joints and shift linkage.  The oil filter cost $1 and the air filter required no maintenance.  Rust doomed the Datsun before the DS.

My comment on the cast iron block was a joke.  Just think how much lighter it could have been with an aluminum engine.

How about if you watch Jay Leno's tribute to the car on YouTube?  Of course he's also biased because he owns one.  I certainly can't outdo him in superlatives.  He didn't mention the 2700lbs. weight though.



Jerry dycus
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Re: real weight savings
Jerry dycus   7/29/2015 9:38:48 PM
Critic, I think it is just we don't do that here corporate diease.

There are disadvantages for them too.

  They don't rust away, they don't need expensive production lines so easy for competition to start up, they need few parts, hard to damage and drilled in them composites cost more.

But those are plus's for the customers.   Also lightweight costs less as less everything.  By making the body, chassis, rollcage frame, doors, hood as 1  piece at 1 time.

A lot of the same reasons most of them don't like EV's, we don't do EV here, we do gas, few parts to replace, batteries repaired with used parts and last forever really lowers profits as fewer 2,000% marked up parts, replacement cars  to sell.

And  already painted not needing the very expensive body, coating, painting process shops, ovens, etc  metal needs. Or the massive metal presses, welding robot  lines, etc.

All done by 3 workers in 2 hrs each with $1,000 of materials in composites to make the composite  body, parts OEM.  Likely 50% of a metal one cost.

With all the strength, weight in the shell it is stronger than hell with all of it reinforcing all the rest with KevlarTM type fabric holding it together if hit making it very, very hard to intrude on in a crash.

It would have to be trapped between hard forces and even then likely to pop out like a watermelon  seed from the body strength.

Because the fibers, etc can be directional in strength unlike metals, one can direct any force where one wants without having the other dimensions increase needlessly causing more weight like metals cause.

It also makes it extremely stiff.  And composite dampen vibrations, sound rather well unlike steel.

The same thing happened in the boating, then aircraft  industry and now it is auto's turn to admit composites are better. 

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Re: real weight savings
Critic   7/29/2015 5:58:30 PM
Jerry, what are the disadvantages of making car bodies from composites rather than steel or aluminum?  Why would an engineer choose not to use composites?  I don't believe it is based on a refusal to admit materials properties.

Quill pens are lighter than ball-point pens, but that doesn't make them better.

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Critic   7/29/2015 5:50:02 PM


70 years and 50 years?  My calculator tells me that 1954 was 61 years ago, but Citroen did spend about 18 years developing the DS.  1974 was 41 years ago, so why did you use the "50 years" figure?  Did the CX also take forever to develop?

You say positive things about the DS, but to be fair, and so people won't think you are a Citroen salesman, here are some of its disadvantages: 

1. It was grossly underpowered and accelerated poorly.  This is fine if you are not in a hurry and don't mind being passed by every other car on the road.

2. It is an ugly, ugly car, and most people don't like the way it looks.  Citroen is famous for making ugly cars.  Beauty is in the eye of the beholder, and it's wonderful that you think it's a great car, but auto manufacturers tend to be more successful when they make good-looking cars.

3. It had head room, but it was narrow.

4. The ride was smooth, but the suspension soft.  Its handling was OK, but nothing to write home about.  There are lots of cars that have better handling characteristics.

5. It had serious rust issues.

Why do you think that cast iron is a lightweight material for engine blocks?

One of the problems with owning an unusual car is that parts and repair labor can be astronomically expensive.

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One step forward two steps back.
cookiejar   7/29/2015 1:36:40 PM
How can a 70 year old deisgn put modern car designs to shame?  Why isn't the remakable design used as a benchmark?

The Citroen DS, introduced in 1954, introduced very low CX, radial ply tires, hydro-pneumatic suspension, first production disk brakes etc. etc. It was very roomy.  At 6'4", I could wear a hat and with the driver's seat set for my height and cross my legs in the back seat while wearing a hat.
It featured lightweight materials like a cast iron engine block, aluminum hood and fiberglass roof bringing its weight in at a very low 2700 pounds.  To put that into perspective: the new Fiat 500 weighs 2600 pounds.  The Citroen model CX introduced in 1974 maintained the same light weight with remarkable safety features - into a barrier wall at 40mph at an angle of 60 degrees leaving 3 of its 4 doors fully functioning - imagine the twisting action on the passenger cage! 

The DS rode smoother than my 4000 pound Buick Lucerne CXS with GM's magnetic ride and handled with utmost precision with no rubber bushings anywhere in the suspension.  I could go on and on about the amazing characteristics of the 70 year old and 50 year old Citroen designs, unmatched by any of today's designs.

It's small wonder that the Citroen DS was voted the most significant car of the 20th century by the international association of automotive writers.  But it seems to be totally unknown by today's automotive engineers.

Jerry dycus
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real weight savings
Jerry dycus   7/29/2015 10:15:10 AM
Sadly these'engineers refuse to admit  that composites is stronger and 40% lighter making these tiny gains look puny because they are.

Notice they use CF as an example on purpose to show how costly compposites are when the correct layup in medium tech FG, Kevlar type fabrics is only a couple % heavier than CF at 10% of the cost.

Not ony that but that layup is far better in crash protection than metal, CF ever could be.

Once you've lost 40% of the body/chassis weight all the other weights drop to including battery packs which composites lower weight saves 35% of the pack for the  same range.

And 30-50% of the weight of everything else.

I can build and have  these body/chassis for less than they do in steel, alum too.

But even when big auto does CF composites like the i3 they sit it on a heavy alum frame, etc that increases it's weight 50%!!! 

As it weighs more than steel cars the same size, what is the point of using CF? 

If the CF body can handle rollover, etc crashes, it can easily hand bolting the suspension, batteries, etc right to the body and leave the frame off.  It is what I, F-1, Ferrari, McLaren, etc do.

Why can't BMW?


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