Hey guys...I'm looking for a brief description on the behavior of the heli with different blade lengths. When I got my heli I had 315 glass blades and she did quite well. I'm still deep in the learning curve and it was suggested to me the 335 blades would stabilize the bird. So I threw a set of 335 woodies on and she is very stable. However, I'm afraid to push her to hard with these blades. Should I be? It sounds like 325 carbons are what most like to use. Can anyone explain the behavioral differences between the 315-325-335 and wood, glass and cf?
Thanks,
quattro

Good questions. I hope you'll get an answer, I'd like to knoww too. I imagine it has some correlation to propellers on planes, but what the actual answer is??? Doc

Generally, the longer the blade, the more stable it will be. The shorter, the more responsive. With the longer blades like the 335 woodies, you can do 3d just fine. Now if you are into hard core 3d, the carbons are the way to go.

I don't do hardcore 3d, but once I switched to my Radix carbons, I'll never go back! They are much more "crips" when you do things like flips and rolls.

Good luck!
Skarn

I'm no expert but as I understand it the larger the rotor disk the lighter the disk loading and the more responsive the heli gets. Also the gyro action of the blades is more so the stability is enhanced as well. This is true of the flybar also. Most Trex owners run the 325s although the Align blades are actually shorter than advertised because they measure then overall instead of from the bolt hole like they should. This means that the Align 325s are actually 315s and so forth. If you buy aftermarket blades they will probably be longer.
I am running the Align 325 Pro wood blades and like them but I have some CF blades on order to see how they work.

is that just because there is less flex? i would imagine that would be the difference between the sizes as well, less pressure on the blade tips for the shorter ones so they dont flex as much. the less flex, the more responsiveness? just a theory.

I agree with Burnt on that one...this is my thinking...CF is the stiffest...after that, i'm GUESSING woodies, then glass. And the longer they are, the more surface area, meaning more lift. But that also translates into more work for the system...there is more resistance due to the increased force generated. then the servos may be working harder to flip pitch quickly, and your gyroscopic effects are greater, requiring more work to deviate off their current path. Thats why flybar weights make such a difference, depending on where they are in relation to the main shaft. I get all that, but its still the basic behavioral characteristics of the different blade sizes and material that I'm after. Like...what blade types are best for what type of flying. Also, I'm wondering if 335 woodies would snap in a furious maneuver, where the carbon wouldn't and even the glass ones wouldn't break, but would flex a great deal...causing a bit of lag...most likely unnoticeable to a noob like me.
quattro

The smaller the disk area the higher loading for a given heli. Blade weight is important as energy is stored in the blades as inertia, If carbons are heavier than woodies they would initally be more responsive. I have a feeling the FRP blades are probably the heavist, but that is just a guess. I think woodies would make an auto nearly impossible, because they are so light. It all comes down to how you want it to fly. The bigger the blades the more stable (lightest disc loading) but a little less response, the smaller the more response due to the motor being able to spin the blades up quicker, and less blade to move around( this assumes same blade material). Think of it is a similar to increasing span on an airplane. In therory the shorter blades would do better in wind. The longer blades also require more power, so flight time would be reduced some. It is all a matter of what you want and experimentation. It would be interesting to fly a Rex on 288s.

would it have enough lift with 288s? I'd assume at some point if they get too small you would lose an insane amount of lift, too big and you would lose alot of power because of the extra size (or you chop your tail rotor off)

You would have enough lift if the headspeed is high enough but it would be slugish in responce. Longer stiffer blades like Cfs are the most responsive due to low loading and high tip speed.
There was a disscussion on longer flybars on RR and there was a consensus that a longer flybar made the heli both more responsive and more stable!