AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Elastic Rotor Bearings from Resilin?          AirTalk.org Forum Index -> Hot air, gas balloons and airships View previous topic :: View next topic   Author Message server Guest Posted: Mon Oct 17, 2005 8:34 am    Post subject: Elastic Rotor Bearings from Resilin? [ message unavailable ] Back to top Guest Posted: Mon Oct 17, 2005 8:34 am    Post subject: Re: Elastic Rotor Bearings from Resilin? These articles quote resilience of 97% compared to 80% for synthetic rubber: http://en.wikipedia.org/wiki/Resilin http://www.future.org.au/news_2005/august/insect.html Other articles mention resilin being used in insect exo-skeletal shells or beetle wings, possibly allowing such structures to store energy: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10983820&dopt=Abstract http://www.livescience.com/technology/051012_insect_rubber.html I couldn't find anything about the UV resistance properties, although perhaps some additive or modifier could be used to give UV resistance. Couldn't find anything on tensile strength, either. Does anyone else know? With such a high mechanical efficiency, I'd wonder if one couldn't perhaps even make flapping wing joints out of it. But what do you all say -- what might be the best way to make use of this material for mechanical airborn propulsion purposes? Back to top Orval Fairbairn Guest Posted: Mon Oct 17, 2005 9:03 pm    Post subject: Re: Elastic Rotor Bearings from Resilin? In article <1129523661.475384.190950 (AT) f14g2000cwb (DOT) googlegroups.com>, manofsan (AT) gmail (DOT) com wrote: Quote: These articles quote resilience of 97% compared to 80% for synthetic rubber: http://en.wikipedia.org/wiki/Resilin http://www.future.org.au/news_2005/august/insect.html Other articles mention resilin being used in insect exo-skeletal shells or beetle wings, possibly allowing such structures to store energy: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids =10983820&dopt=Abstract http://www.livescience.com/technology/051012_insect_rubber.html I couldn't find anything about the UV resistance properties, although perhaps some additive or modifier could be used to give UV resistance. Couldn't find anything on tensile strength, either. Does anyone else know? With such a high mechanical efficiency, I'd wonder if one couldn't perhaps even make flapping wing joints out of it. But what do you all say -- what might be the best way to make use of this material for mechanical airborn propulsion purposes? As I posted earlier, it sounds interesting, but I am not going to build something that depends on it until I can evaluate its mechanical properties and how they stand up to the effects of aging, UV, heat, cold, the usual solvents, fuels and lubricants found in aviation. Until we have that information, resilin will be a potential, but unproven, material. I would suggest that it be tried on model airplanes, etc., to get a feel for its real-world properties. Back to top Guest Posted: Wed Oct 19, 2005 1:18 pm    Post subject: Re: Maximum Theoretical Balloon Size? hello der!. try to visit this, http://www.tpub.com/aviation1.htm it might provide answer. the link was posted on the other group, im already visited it, so im sure it wasnt a virus or whatever that can harm ur comp. manofsan (AT) gmail (DOT) com wrote: Quote: What is the maximum theoretical size possible for a lighter-than-air balloon, using ideal materials, before it loses its integrity? Here's an article from a month ago, about sheets being made from the famous nanotubes: http://www.eurekalert.org/pub_releases/2005-08/uota-utd081505.php http://en.wikipedia.org/wiki/Nanotube quote from Wikipedia: "Ray Baughman's group from the NanoTech Institute at University of Texas at Dallas produced the current toughest material known in mid-2003 by spinning fibers of single wall carbon nanotubes with polyvinyl alcohol. Beating the previous contender, spider silk, by a factor of four, the fibers require 600J/g to break. In comparison, the bullet-resistant fiber Kevlar is 27-33J/g. In mid-2005 Baughman and co-workers from Australia's Commonwealth Scientific and Industrial Research Organization developed a method for producing transparent carbon nanotube sheets 1/1000th the thickness of a human hair capable of supporting 50,000 times their own mass. In August 2005, Ray Baughman's team managed to develop a fast method to manufacture up to seven meters per minute of nanotube tape. Once washed with ethanol, the ribbon is only 50 nanometers thick; a square kilometer of the material would only weigh 30 kilograms." ------- So if the limiting factor is tensile strength, and nanotube fibres are the record-holder at 600J/g tensile strength (20x stronger than kevlar??) while also having a mass of 30 kg per sq km, then how big can one make a balloon held together by the nanotubes? And what kind of displacement lift force would it exert? 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