MAB123 Posted February 27, 2023 Share Posted February 27, 2023 I am after some information on the correct way to mount a Sweet Apple prop on a Jabiru 120 We have one based on our airfield and there is several theories on the mounting bolts and type of washers to be used Flat or Belleville Washers Link to comment Share on other sites More sharing options...
Kenlsa Posted February 27, 2023 Share Posted February 27, 2023 Wooden prop should use Belleville washers, just like the jab wooden prop. 72 inch pounds of torque Ken Link to comment Share on other sites More sharing options...
440032 Posted February 27, 2023 Share Posted February 27, 2023 NO NO NO! Not all wooden props are the same! Your prop MAB123 should be mounted according to the manufacturer's directions. JABIRU wood props have specific instructions and torques for the wood they are made from (Hoop pine). I own a Jabiru and Jab prop. Then, BRENT THOMPSON PROPS instructions where NOTHING like Jabiru and they have different torques for different bolt sizes too! I'm looking at his sheet NOW. His props were not hoop pine. I owned one! Other props will be different again. I cannot stress this enough with wood props: DO NOT USE GENERIC MOUNTING INFO YOU READ ON SOME FORUM ON THE INTERNET! Sorry for the rant, well ah, NO, I'm not actually, holy shit........ Mounting propellers properly is not a game of chance and guesswork. That's how they come off! Checking prop bolt torque is also an occasional maintenance task too, as per your prop instructions, remembering that seasonal temp/humidity changes need seasonal checking too. NEV, jump in here please! Link to comment Share on other sites More sharing options...
facthunter Posted February 28, 2023 Share Posted February 28, 2023 I can't add to much what you've said Torsional harmonics are something you can't feel but can involve LARGE torsional forces. Effectively Jabiru have a flywheel at both ends of the motor. Also wood props have moisture in them and the hub gets hot. IF the wood dries it shrinks. Props rely on CLAMPING forces so it's important to get it right. WOOD is probably the most forgiving material to use, but the efficiency will be below others and rain can damage it. Hub design could be better on some installations. (Take the bending load off the bolts). Nev Link to comment Share on other sites More sharing options...
MAB123 Posted February 28, 2023 Author Share Posted February 28, 2023 Hi 440032 Thanks for your blog After much searching the web I can't find anything on Sweet Apple props The designer got very sick (and as I understand he is no longer with us) the business had 2 owners after him and now has shut down . Can you forward to me any info you have on Sweet Apple props at [email protected] Thanks Link to comment Share on other sites More sharing options...
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