Well Mark I am not sure how we jumped from models to full size aircraft, having been in the RAF I do know that props fell of sometimes too. To answer your question if I turned a prop of similar size & pitch in air & then in water at the same RPM there would be a lot more resistance in the water, putting a much greater strain on the attachment point, to Peter if I remember when the issue of joints came up before you submitted a photo of some joints that you had made using speedo cable to get around alignment problems (very nice too) We all have our pet ways of doing things, because of 50 years in the Auto trade of which I spent 19 years racing as an amateur Murphy's law is always in force. The surface area covered by the end of a grub screw is less than the area covered by the same screw if properly tapered & screwed into a corresponding tapered indent in a shaft. In most cases a flat will also do the job just as well, two flats & two grub screws would in most cases be even better, however I would use the indent method on my boats. If you employ a grub screw from both sides 180 degrees apart you double the strength of the attachment, this is dependent on shaft diameter, too thin a shaft & it will weaken it & probably cause it to fail. For your information Martin we do not fit engine & gearbox mounts for alignment purposes, in fact in many instances we use shims under mounts to correct the alignment of the driveline. You must also make sure that the U/Joints are phased correctly. When the issue of noise & joints came up on this forum before John (oldiron ) tested several joints & found that the Huco was at the bottom of the list, I wonder Martin if you could find the thread in question & post a link to it on this thread ?. I have spent time & some money trying to invent a better joint for our hobby & have come up with a basic model. I have had problems making it precise enough up to now, it works but has some vibration because it is not precise enough. However I have ordered a milling machine ( it is now awaiting pickup & a rather large cash payment LOL) which I think will give me the precision that I require. Don't get me wrong I will use the mill in lots of ways but a strong motivating factor in buying it was to try & make a better U/ Joint, I never take NO for an answer & those that do drive me crazy (if I am not crazy already) If I am successful the forum members will be the first to know either way. In my search for a better joint I also found a C/V joint in the model car section of my local hobby shop that with machining may work well also. It does require a lathe to modify it though. I took a chance & spent $80.00 & brought one home. Up to now it looks really great & is easy to fit, I would say 90% that it is better than anything we can buy right now but who am I to say.When I have more testing done I will post the information on the forum, either way. I am trying to be funny here but I say to those that always say it can't be done, take a long walk off a short pier LOL, progress on this planet has come from those that never took NO for an answer. Mick B.
