Olly Giles Posted June 18, 2011 Share Posted June 18, 2011 How do you select a 3 blade prop to directly replace a 2 blade prop. So if i am currently using a 16x10e prop what would be the 3 blade equivilant? Quote Link to comment Share on other sites More sharing options...
John Privett Posted June 18, 2011 Share Posted June 18, 2011 You'll want to reduce the diameter but keep the pitch the same. The rough "rule of thumb" was always to reduce the diameter by an inch - though that was in the days when a "typical" prop was 10 or 12 inches diameter, so on a 16" prop you may need to come down by more than an inch. I'd try a 15x10 or possibly a 14x10. Presuming the "e" indicates you're flying electric then you should check with a wattmeter that the current is still within limits before flying. If somebody has Motorcalc or similar it would be interesting to see what numbers it comes up with. Quote Link to comment Share on other sites More sharing options...
Josip Vrandecic -Mes Posted June 18, 2011 Share Posted June 18, 2011 Graupner equivalent prop list (OS 70 4 stroke ) looks like this : 11-7'' (three blades) and 12,5-6'' (two blades). note: OS and Graupner only .....it might be helpful...Cheers Jo Quote Link to comment Share on other sites More sharing options...
laurent Muchacho Posted September 5, 2011 Share Posted September 5, 2011 Anyone got a tip or Technic to balance 3 blades prop? I've got a balancer that I know how to use to balance 2 blades prop but found it difficult to balance 3 blades prop Many thanks Quote Link to comment Share on other sites More sharing options...
Former Member Posted September 5, 2011 Share Posted September 5, 2011 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
laurent Muchacho Posted September 6, 2011 Share Posted September 6, 2011 If you buy graupner props I agree, you don't need to balance them but I do have some gws 3 blades that need balancing. Same with all Giantcod 3 blades prop I've received. If you don't need to balance new prop your are lucky but only a few wood prop, master airscrew and Graupner are perfect out of the box but most other need balancing from my experienced. On my e2k pylon plane I do have to precisely balance every prop even if the prop is balanced sometime the hob will be a bit unbalanced meaning the density of the nylon is denser on one side of the prop. This will not usually cause problem or even noticeable vibration on most plane but on the e2k 650W make you realise that each prop need to be perfect. Please any tips on balancing 3 blades is welcome Laurent Quote Link to comment Share on other sites More sharing options...
laurent Muchacho Posted September 16, 2011 Share Posted September 16, 2011 There it is how to balance 3 blade prop http://www.phprc.net/images/RC_Aero_-_3_Blade_Prop_Balancing_Technique.pdf His technique work really for big prop but for small prop like tha gws7x3.5 3 blade if you scrap/sand from the heaviest until it balance with the lightest you will mainly scrap too much of the plastic on the blade making the blade more flexible and less efficient. The the way I do it is has follow 1) follow each of the step described 2) found the lightest blade (1 dot blade) move (3 dots blade) to the top and add weight to number one until it balance with number 2 3) now you can scrap/sand out of number 3 until it balance with the 2 others Hope that help. Please feel free to ask any question Quote Link to comment Share on other sites More sharing options...
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