Quote:
Originally Posted by All Darc
Sorry to disagree with you now. But a rocket it's mostly fuel in weight, so if you cut for the weight of the empty body of a rocket in 99%, it would still be incredible heavy (98,99% of weigh if with fuel added), due the weight of fuel.
A Airplane would take some benefit.
But a car, with only 10% of fuel weight of total weight, and so a90% of weight for the car's body (shape/reels/motor...) and if we could cut 70% of the body weight, the final car (with fuel) would be 40% of the initial car's weight with fuel.
You had reversed the fuel weight important analysis.
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Most of the fuel in a rocket is consumed merely accelerating the weight of the fuel. To add a small amount of payload or rocket structure, more fuel must be added, but then a lot more fuel must be added to simply accelerate the weight of the additional fuel. For this reason, a small difference in weight translates to big differences in fuel consumption.
Aircraft have a higher payload to fuel ratio than rockets, but it is still not great. Adding a little weight has a medium impact on the additional amount of fuel required.
Automobiles have a very high payload to fuel ratio. Adding a small amount of weight has little impact on the fuel consumed. Add 200lbs to your car and drive 100 miles on the highway, and you won't even be able to tell the difference in fuel consumed. Any fuel consumed going up hill is recaptured coming back down the other side. In fact, moderate hills can be more efficient for driving a petrol car than flat roads (forced pulse and glide).
The higher the ratio of payload to fuel, the less important weight reduction is.
As shown in this forum, aerodynamic improvements are much more effective at improving fuel economy than weight reductions.
Quote:
Originally Posted by All Darc
Carbon fiber it's a cable, a strong cable on a jail of epoxi resin. If epoxi resin are not strong enough to keep the fiber on jail under pressure... we have a problem.
Again, one more crap carbon fiber product :
Who knows a carbon fiber product for sale that do not behave like a crap?
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As you point out, carbon fiber is strong as long as it is engineered to take advantage of its strengths and avoid its weakness.
How much would a bow rod made of steel weigh? A similar diameter and thickness steel rod could be stronger, but it would also be much heavier.
Most bicycle enthusiasts prefer a carbon fiber front fork both for weight reduction and bump absorption. There are plenty of consumer products where CF is the appropriate material of choice.