Art. Yes I know that the control surfaces of the DC3 are fabric covered.
That's why I mentioned the wings explicitly. I think that several war birds from that time also had cloth covered control surfaces. It seems to me that the loads on those surfaces are less than on the wings, which in the case of a bomber must have been high. However, I am not out to prove that either wings are better - cloth or metal covered. I flew both in Ercoupes and trusted my life to them. I only see there are advantages and disadvantages in both covering methods and as an honest forum we should mention both, not only those that we personally are in favor of. Especially when we give advice to a person that is new to Ercoupes. I don't want to be in a position of talking someone into buying something he later regrets. Best is to be objective here and list the advantages and disadvantages without prejudice. Hartmut CC: [email protected] From: [email protected] Date: Thu, 10 Sep 2009 15:24:22 -0500 Subject: Re: {Disarmed} Re: {Disarmed} [ercoupe-tech] Metal Wings are stronger..... One last comment on this thread as far as small aircraft are concerned, there is also the question of the inefficiency of craftsmanship vs mass production as far as fabric is concerned. It's not all about strength. Helmut, I assume you know that the DC-3 has fabric control surfaces, including the ailerons? :-) Art Art Langston wrote: William, would you then suggest that either covering is there primarily to create lift, rather than provide structural integrity on a wing of this design? That was my conclusion. Art N2666H William R. Bayne wrote: I would suggest that any engineering evaluation use the correct approach in evaluating "stronger". Adding thin sheets to a wing structure already designed and capable of coping with the normal stresses of flight (plus a considerable safety factor)would add little, if any, to the overall load carrying capacity of an Ercoupe wing in terms of the additional stress said could carry before it failed under load. The materials and procedures utilized by the various STCs presently installed or available does not transform the Ercoupe wing designed for grade A cotton covering into a monocoque structure as would seem to have been inferred. "Monocoque" construction is defined as "an aircraft structure in which the outer covering skin carries all or a major portion of the stresses". The internal structural components, metal skin thickness, rivet type, size, and spacing of a stressed skin wing design would be quite different, and likely lighter. Consider also these questions: 1. What practical purpose is served by increasing wing strength beyond regulatory design requirements? 2. How much has the load capability of Ercoupe wing design increased when covered with modern synthetic fabrics of higher tensional strength abd durability than the original grade A cotton? Regards, WRB -- On Sep 10, 2009, at 13:05, Art Langston wrote: Chris, could you please share the engineering data with us and cite the documentation where we can read it? When finished, I believe the Polyfiber may actually be stronger than the aluminum. I've de-skinned Ercoupe wings, and the metal is very thin. Polyfiber is tough. Thanks Art N2666H Chris wrote:A metal wing is stronger than a fabric one. The metal distributes the loads over the surface. Would anyone want to consider a fabric covered fuselage? Chris Santa Cruz 99674 ‘--o-O-o--’ _________________________________________________________________ Windows Live: Make it easier for your friends to see what you’re up to on Facebook. http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_facebook:082009
