To quantify the weight savings of advanced composites the chart below compares various metals and various advanced composite fabrication methods & materials. The chart below shows the weights of given materials to yield roughly the same strength irregardless of the material, yet their weights are vastly different.

stainless steel 30lbs  
aluminum 15lbs  
solid E-glass (fiberglass) 15lbs  
solid carbon fiber 9lbs or less  
Kevlar skinned honeycomb core 3lbs or less  
carbon fiber skinned honeycomb core 2.5lbs or less  

Weight savings is one of the key advantages of using advanced composites. The second main advantage in using advanced composites is that the CTE (coefficient of thermal expansion) can be minimized. The chart below shows CTE figures of different materials.

Nomex honeycomb core 20  
magnesium 14.6  
aluminum (2024, 6061, etc.) ~13  
brass ~11  
copper ~10  
stainless steel (303 to 403) 5.5-9.7  
gold 8.2  
E-glass (fiberglass) 7-8  
steel 6.5-7.5  
nickel 7.4  
titanium  4.8-5.6  
zirconium  3.2  
Kevlar 3 and lower
carbon fiber - basic woven material 2 and lower  
invar 1.6 and lower  
specialized composite materials ~0  
unidirectional carbon fiber slight negative (longitudinal)  

All figures listed above are in inch/inch degree F.

All of the materials listed above can be produced in a variety of ways. Those variations each have their own specific CTE. Thus the chart above is a rough reference for CTE's of different materials. In reality material properties are much more complex than the chart implies. For example, carbon fiber can have a broad range of CTE's, say -1 to 8+, depending on the direction measured, the fabric weave utilized, whether the material was produced from Pan based (high strength, higher CTE) or Pitch based (high modulus/stiffness, lower CTE), etc..

Minimizing the expansion/contraction is a prime objective as it can influence much more than just focus: optical spacing, collimation, etc.. Advanced composites can be chosen that not only reduce weight but also optimize CTE.

To learn more about advanced composites, click here.