honeycomb cores 1

[djaytch99]

My question concerns the X-33 spaceplane and the use of honeycomb cores in composites.

My understanding of the situation is that the program was cancelled due mainly to the failure of the composite fuel tanks, which, after core delamination was detected, it was decided to use a different material thus increasing the weight, resulting in reassessment and eventual cancellation of the program. I'm sure that is an over-simplification of the circumstances, but what puzzles me is that for many years now state-of-the-art in honeycomb technology has always revolved around the industry standard: ie strips of metal or similar, glued together to form hexagonal open-ended tubes of varying diameter and length.

My interest in this subject stems from the fact that due to my own discovery of a new method of producing honeycomb, I have been searching the patent databases to see what the competition has to offer. Imagine my surprise to find that there are literally hundreds of ways to form honeycomb, many of which could possibly do a better job than current designs. It doesn't seem to matter whether it's aerospace, powerboats, automobiles or whatever, good ole' state-of-the-art honeycomb is where it's at, and always has been! So, what is the problem?

david

 

[ishvaaag]

I venture to think it won't be in reality a honeycomb particular structure problem, but the weight of any of those envisageably at hand. A little more weight and the reusability of the vehicle turns inviable, hence for now the concept itself... or maybe the issue is not technical at all and budget or even strategic measures advise to cancel the program for whatever the reason and a seemingly acceptable cause is blamed for. Spatial systems allow for many unknowns in so complex activities and to most unfathomable deep purse budget procedures.

 

[vonlueke]

Though I'm no expert on this subject, here's some speculation, comparing honeycomb versus rigid foam core. Honeycomb core: far more difficult to manufacture, susceptible to handling/transportation damage, low adhesion surface area hence face sheet delamination issue, anisotropic properties for analysis, good for high-heat applications, expensive. Rigid foam core: extremely easy to manufacture, very large adhesion surface area hence less delamination problem, ultra lightweight, almost as strong if not as strong as honeycomb (?), better impact resistance, better insulating and dampening properties, isotropic properties for analysis hence easier to analyze, better resilience if buckling occurs, extremely inexpensive, no good for aerospace or other high-heat applications (except metal foam, expensive).

As you mentioned, for high-heat applications, it seems if any honeycomb design maximizes adhesion surface area, it should have been great. Or perhaps metal foam core would have been good.