What prop
 

Hey guys,I've got an 82 saito with a 14X4w on it in a H-9 t-34. Would like a little more ground clearance and would like to go to a 3-blade prop. Can't find any recommendations anywhere. I like the 14X4w becauseit doesn't fly real fast and has lots of torque. Any suggestions would be really appreciated.TIA, Tom

RE: What prop
 

TJ, I'm tempted to recommend a 12x6 three blade, I could try one tomorrow PM on my .82

RE: What prop
 

12X4 or 12X6 3 blade should work. The 12X4 would give better pull, but a 2 blade would be more efficient. An APC 13X6 or 13X7 would be about the best 2 blade for short clearance without losing power to gain speed.

RE: What prop
 

2 bladed props aren't always as efficient as a 3 bladed one. There are aerodynamic advantages to 3 bladed props at times.

RE: What prop
 

Mostly when running at lower rpm than we traditionally spin our two-bladed props.


Ed Cregger

RE: What prop
 

Hobbsy, Thanks for the quick reply. Would be interested to know what results you get. Thanks for all the responses. A 12X6 3blade sounds like the way to go.Tom

RE: What prop
 

TJ, I got to try one prop a few minutes ago. On gut instinct I tried a MasterAirscrew 12x8 three blade, I did not any more than start the engine when my neighbors came out and began preparations for a swim party. I had three other props laid out to run, a MA 11x8-3b, a Graupner 12x8-3b and a MA 12x6-3b. I cut it short and just did the MA 12x8, I'll do the others tomorrow when I get back from flying.

Saito .82 GK
Prop==MasterAirscrew 12x8 (3) blade.
Fuel====WildCat 15%/18% 80/20 syn/castor blend
Plug====GloDevil 4C Special OS-f equiv. (Thats what it says on the package)
RPM====9,475, idle 1,825

That old saw about 3 bladers being ineffecient went out the window with Fred Flintstone. Here is picture of the .82 turning an APC 14x6, nearly identical rpm.

RE: What prop
 

The only way I've noticed that 3-blade props are less efficient than 2-blades is when you whack them. You get to spend twice as much money replacing, so in that respect anyway, they're less efficient. Now in terms of flying... :)

RE: What prop
 

The financial efficiency (or inefficiency) is a lot easier to understand than the aerodynamic stuff. I'm cheap (or "efficient") so I'll have to stick with two blades.

My rother replaced a 12x6 two blade with a 10x6 three blade on a trainer and got similar rpm numbers with both props. The two blade did have more static thrust; but, on the trainer, flight performance was pretty similar.

RE: What prop
 

Hobbsy, you should have joinedthe swim party!! The 12X8 looks pretty good. Would like to see what you get on the other two.Tom

RE: What prop
 

That is exacty what efficiency is, less dough per mile. We don't travel in R/C planes so efficiency is not always the upmost. People confuse effective with efficient. Using a glow engine is more effective than a gas engine, but it is not more efficient. Sometimes a prop may be much more efficient than another, but if it won't hover your 3D plane it's not going to be very effective.

RE: What prop
 

MA 3-blade props get pretty good RPM for their advertised size. However, I find that the pitch flattens. My plane with 14x7 3-blade @ 9500 rpm flies at below 50 mph top speed. Theoretically it should be close to 65 mph. MA plastic props flatten pitch at the tips, which will increase rpm, but not necessarily performance.