Steve you have to think about what you just wrote there. Not much difference between foam and ply except for density and weight. If the skin is properly laid up per manufacturers spec the resulting structure will be the same.
Mahogany ply is widely available around the world and has been used for years in aircraft construction the same as spruce. Reinforcing these woods with glass, whether E, S (my preference due to it's low cost and higher resistance to heat), Kevlar or Carbon will only make the resulting structure stronger. None of this is engineering but only logic as both wood and foam absorb resin during the lay-up process. Edwardo's idea allows a much easier fuselage construction in my humble opinion as the wood formers definitely take the guesswork out of sanding the foam to shape and assure that both sides are identical. It also allows an infinite choice of shapes as witnessed by the War Replica designs that follow the KR type box boat with wooden formers added to allow the builder to replicate what ever design he/she has chosen. Doug Rupert Simcoe Ontario >> >>> >> Steve - I hope you get the answer and also tell me as this is exactly what I would like todo. The one thing between me and a KR is the boat structure. I realize that many have been made like that and most of them look very good. I helped someone do this and the plywood was creaking when he pulled the sides together. the plywood was already stressed nearly to breaking before the thing even looked like an aeroplane never mind started bearing flight loads. As said many times before the sides bow to a banana shape even more when you increase the seat width. This is an interesting and valid KR topic. at least one KR is being built this way and if ron and steve and me are interested in eduardos way then help us get it right or stay away. Doug - lets look at some of what you say and maybe you must also think about what you say. "Not much difference between foam and ply except for density and weight" Well - also not much difference between lead and feathers, just the colour. Oh and the weight. "If the skin is properly laid up per manufacturers spec the resulting structure will be the same." The manufatures spec calls for ply so anything else is not properly done and not as per the manufacturers spec - that is the whole point of this discussion. "Mahogany ply is widely available around the world and has been used for years in aircraft construction" I dont think anyone will dispute that it is widely used for aircraft. Steve J, you have been caught out telling fibs - you said good ply was a problem for you in africa, shame on you. "Kevlar or Carbon will only make the resulting structure stronger" Steve, better tell this zeke fella he has it all wrong - you can mix and match carbon and even kevler with spruce, ply, lead and feathers. no problem. (BTW My brief experience with kevlar was definitely the last. It may be good for bulletproof vests but not good for composite work. trust me.) "None of this is engineering but only logic" Phew - I was starting to worry. im no Engineer but I amok with logic "both wood and foam absorb resin during the lay-up process" I had this one all wrong. I figured that the whole idea behind a micro slurry (paste?) over the core was to prevent any unwanted weight build up from absorbed resin. "War Replica designs that follow the KR type box boat with wooden formers added to allow the builder to replicate what ever design he/she has chosen." Total agreement with this one - the WAR replicas have a complete KR type boat with the plywood and all - complete and competent being the point, no deviations or material substitution. The moldless foam appendages are non-structural fairings to achieve a given appearance. i think this is a bit different from the present topic that is all about glass foam as an integral part of the structural integity of the boat. Sorry gang - maybe unneccessary to say it this way, but it is an interesting and relevantKR topic and it would be magic if we had some informed input as why this is OK or not Ok or how to better do it. I did feel obliged to state point for point why I dont see any contribution value from dougs input. Edward ___________________________________________________________ALL-NEW Yahoo! Messenger - all new features - even more fun! http://uk.messenger.yahoo.com
