Robert Cracknell Posted November 2, 2022 Share Posted November 2, 2022 Basic question, but is there a conversion/chart/rule of thumb/guesstimate method when selecting a 3 blade prop to replace a 2 blade...? Quote Link to comment Share on other sites More sharing options...
Nick Somerville Posted November 2, 2022 Share Posted November 2, 2022 I don’t know about ‘electricary’ powered models, but for IC it is generally not worth going to three blades unless your engine is more than 100cc. Nothing to stop anyone fitting an appropriately sized three blade prop, but it won’t be as efficient as a two blade one. Quote Link to comment Share on other sites More sharing options...
Andy48 Posted November 2, 2022 Share Posted November 2, 2022 I fitted one to one of my electric models running on a 4S. Bought a cheap one first and it was useless. Bought a better quality one and it was very good, equally comparable to a 2 bladed prop. Didn't notice any loss of efficiency. I couldn't find any comparison chart, but then the range of sizes for 3 bladed props is quite limited. Often wondered about this loss of efficiency thing. There are plenty of civilian and military planes using multi-bladed props for various reasons, usually for ground clearance reasons like the Spitfire. Can't be all that bad. Then there are wind turbines. Hmmm. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted November 2, 2022 Share Posted November 2, 2022 1 inch down on diameter. 3 Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted November 2, 2022 Share Posted November 2, 2022 Some chat here as well, links on thread don't work, from old platform/forum. Quote Link to comment Share on other sites More sharing options...
Andy48 Posted November 2, 2022 Share Posted November 2, 2022 7 minutes ago, john stones 1 - Moderator said: 1 inch down on diameter. I seem to think this is what I used as a rough guide. 2 Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted November 2, 2022 Share Posted November 2, 2022 From my experience there are two main differences after the drop an inch method. Firstly there is just not the same choice of three blade props, not a problem if you change cell counts on the battery (assuming you can) to get the best set-up. Secondly three and four blade props shift more air at low RPM compared with a two blade, so great at getting going but can be a bit of a hand full when landing as they are more on/off with their thrust + produce more drag so no chop and glide! Plus they seem to run out of puff at higher motor/air speed, probably as the motor is just spinning a blade in the wash of the previous blade. IIRC a lot of the larger scale models have a 3 or 4 blade for show and then the owner swaps to a 2 blade for flight!..does that tell you something? Quote Link to comment Share on other sites More sharing options...
Frank Day Posted November 14, 2022 Share Posted November 14, 2022 As other have said, drop one inch in diameter and be prepared to play around with the pitch and different brands and run tests Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted November 14, 2022 Share Posted November 14, 2022 On 02/11/2022 at 17:21, Robert Cracknell said: Basic question, but is there a conversion/chart/rule of thumb/guesstimate method when selecting a 3 blade prop to replace a 2 blade...? If it's for an electric setup use propCalc Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.