I've seen this topic for years and so decided to see what it would take to break a 1/8" carbon rod with my hands which have considerably higher bending capability than a stab on one side of a vertical. Try it for yourself, try to use your hands to break a 1/8" carbon rod, just past half way along its length. It will be interesting to hear your findings bout how easy or hard it is...and why it might be possible for a stab to put that kind of force on the rod, with out it breaking first. Note I didn't say it was hard, I'm asking you interested parties and suggesters to 'do' something then report. Gordy In a message dated 4/25/2008 9:55:54 A.M. Eastern Daylight Time, [EMAIL PROTECTED] writes:
That may be overkill, if the 1/8 was almost strong enough. Assuming that the wall is pretty thick, 1/4" would be 8X as strong and 16X as stiff, if I'm not mistaken. I wonder if the problem is that the rod is not very strong crosswise, so if there's a hint of a sharp edge, maybe it will crunch. A steel tube might be a good compromise, though the yield strength, unless you go pretty high tech, will be maybe half or less that of music wire. Presumably the diameter would make up for that, given the right wall thickness, etc. (I'm assuming you'd use a little piece of 4130 or something from Aircraft Spruce) I wonder if one glued short lengths of brass tubing over the carbon at the appropriate places if that wouldn't help keep local loads from messing it up. Especially if you ground the edges to a taper. Or maybe that's just too much trouble. The 1/4" carbon might weigh 7 grams or so if it was 4" long.. A 1/8" steel rod would weigh about the same for the same length. The carbon would be much stiffer, of course. And if you loaded it carefully, with only smooth edges, a heck of a lot stronger. However, assuming a 24" stab with 100 square inches or so, the 1/8" joiner on the tail would stand up to an airspeed comparable to that of a 1/2" steel rod of the same yield strength on the wing. However, music wire tends to have a really high yield strength. (plus or minus a lot depending on design details) > : <[EMAIL PROTECTED]> wrote: Ray, I have used 1/8 cf rod > for stab axles, and had them break. This was on my Yardbird design, > 130". I went back to steel rather than try to go to a bigger tube. My > latest will use 1/4 cf tube for stab axles. Jack > -- RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format **************Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos. (http://autos.aol.com/used?NCID=aolcmp00300000002851)
