Tim Flyer Posted October 2, 2021 Share Posted October 2, 2021 (edited) I would be interested to hear peoples views on the use of aluminium domed nuts as prop retainers especially for large four stroke glow engines. Obviously they have been used over the years on smaller 2stroke glow engines. What I’m concerned about is that an aluminium thread is subject to wear and it would be hard to generate sufficient torque without distorting/damaging the nut in order to safely retain the propeller. Given the high torque of a 4s engine and occasional low rpm vibration I don’t think a single aluminium thread is suitable. I think the domed nut design where the rear is hollowed out to accept the manufacturers steel nut and washer behind it is much safer for larger engines. Please see pictures of by my P47 domed nut from Just Engines. This nut allows the steel manufacturers nut and washer to be used to properly retain the propeller behind it. Edited October 2, 2021 by Tim Flyer Typo Quote Link to comment Share on other sites More sharing options...
J D 8 Posted October 2, 2021 Share Posted October 2, 2021 The standard domed nut has a lot more thread in contact with the shaft thread than a nut and this may well make up for the softer material. Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 2, 2021 Author Share Posted October 2, 2021 Thank you. I see that might reduce the torque required to prevent loosening …. Certainly when I do up the steel nuts with a spanner, I put a fair bit of torque in. Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 2, 2021 Share Posted October 2, 2021 The torque needed to strip an M8 or M10 thread in aluminium will be significant and far beyond what is possible with a T bar. You would really have to go some with a long spanner to get enough torque on it to strip it. I used an ali dome spinner we made at Laser on my stampe when it first flew and never had any problem. I stopped using it as i didnt have a suitable flat washer and it was munching the prop face when i did it up with the T bar. Also, the 5mm T bar wasnt really man enough for the job. I could have used a c spanner but i didnt have one and didnt want to buy one just for that job. In response to the overall question though Ali is fine as a dome nut provided you can tighten it to the required torque so normally spanner flats will be needed on larger nuts as a T bar will not do the job. Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 2, 2021 Author Share Posted October 2, 2021 Thank You very much for your detailed reply Jon …good to hear. As you said It seems the main issue is simply being able to apply the required torque Quote Link to comment Share on other sites More sharing options...
Nick Somerville Posted October 2, 2021 Share Posted October 2, 2021 Lovely long dome nut from Jon on my P47. I also wasn’t convinced I could get sufficient torque with a rod through the hole, as it isn’t that big, so I drilled out a hollow so it tightens over the regular prop nut as you mentioned in your post. Works great and I like to think of it as a lock nut for added security. BTW Tim, since you saw it’s shaky maiden it is now well sorted and a brilliant model to fly. 1 Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 2, 2021 Author Share Posted October 2, 2021 Cheers Nick your P47 Looks superb ! You did a great build. I’m really pleased you now have sorted it out. I really love flying my P47 too . I have often heard they are a “really friendly Warbird to fly” , and I certainly agree. My model is only an ARTF Seagull with a Laser 100 but I definitely enjoy it very much . It’s the plane that really got me hooked on Warbirds. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 3, 2021 Share Posted October 3, 2021 oh dear who has been telling lies,,,? Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 3, 2021 Author Share Posted October 3, 2021 15 minutes ago, Paul De Tourtoulon said: oh dear who has been telling lies,,,? Do you care to elaborate? Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 3, 2021 Share Posted October 3, 2021 Pinocchio ? Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 3, 2021 Author Share Posted October 3, 2021 I think you need to let everyone in on your joke Paul ……although I’m sure it’s very funny and sophisticated. I’m not sure what you mean by posting the picture with website listed on it ? Quote Link to comment Share on other sites More sharing options...
Richard Acland Posted October 3, 2021 Share Posted October 3, 2021 Pinocchio had a nose that grew longer when he told a lie. The pun is intended to indicate that the prop nut in the photo is quite long. Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted October 3, 2021 Author Share Posted October 3, 2021 Aha get it … I thought he was referring to my earlier post Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 3, 2021 Share Posted October 3, 2021 Sorry, so next time I will post a book on my rubbish jokes so as not to offend,,,? 1 Quote Link to comment Share on other sites More sharing options...
Nick Somerville Posted October 3, 2021 Share Posted October 3, 2021 They all look quite long, even the shortest one noted on the Hamilton Standard Prop. Fibs all round then! 2 1 Quote Link to comment Share on other sites More sharing options...
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