View challenge: C-0150-0103 - Seeking a method for attaining extreme cantilever using a coilable material
We need to extend horizontally the loose end of a small coil of lightweight stored material without external support -- essentially, achieving a cantilever supported only at one beam end. Material, beam cross-section, and beam structure are on the table -- but your solution must meet strict criteria in terms of size, weight, cost, and coilability.


We envision that there may be a better engineering or materials solution to our problem than the one we now use. We store a small coil of lightweight material (the coil size can fit in the hand), the loose end of which must extend horizontally from the coil for well over 168 unsupported inches without deflection anywhere along the extended length or at the root of the beam. There is no additional load on the cantilever beam other than the weight of its own material.

In its current design, the material form factor is long, narrow, light, and thin. We would like to maintain that form factor to the extent it is possible.

There are a number of basic engineering solutions, such as changing the cross-section of the beam to that of a channel. I-beams, for example, are two channels back-to-back, and an I-beam form easily could span 168 inches. However, the material must be able to be re-coiled for storage, and -- as always -- there are manufacturing cost considerations.

Likewise, there may be a materials solution. We are open to a materials change, and it may be that co-extrusion or some similar process using polymers could produce the tension and compression coefficients needed to maintain the cantilever and still allow light weight and enough flexibility for storing the material in the form of a small coil.

We are unlikely to reconsider the coil as the form of storage, but that is not impossible if you can propose an alternative means of compactly storing over 168 linear inches of material in a form that one hand can hold.

All potential solutions must face tight cost constraints. Exotic materials or difficult-to-manufacture options may be non-starters (even if successful solutions) because of costs. Your solution to this cantilever problem will need to be manufactured hundreds of thousands of times, and must cost accordingly.


o Tight cost constraints.

o Able to extend horizontally 168+ inches without deflection or support except at one beam end. A greater cantilever extension would be even better.

o Able to store 168+ linear inches of material in a small coil (or in another compact storage form able to be held in one hand) no more than 3-to-5 inches in its largest dimension.

o Gross weight under 1 pound.

o Manufacturable in a cost-effective manner.

o Dimensionally stable and able to withstand most reasonable outdoor conditions.

o Patentability.



Aerospace structure design

Space science

Materials science

Polymers and extrusion
Key Expectation from the solution
Must Meet
 A 168+ inch cantilever in a coilable material
Must Meet
 Gross weight under 1 pound
Must Meet
 Tight cost constraints
Good if Met
Good if Met
Good if Met
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Challenge Start date: 07-May-10         
End date: 31-Aug-10
 In progress
 Need attention