Question? What Determines A Good Helicopter Blade

Discussion in 'The Chat Room' started by smakmeharder, Feb 4, 2015.

By smakmeharder on Feb 4, 2015 at 10:51 PM
  1. smakmeharder

    smakmeharder Administrator

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    I have tried blades that look very similar in profile yet fly completely different. I would like to know what attributes are responsible for the following:

    Bite: what shapes determine how aggressive a helicopter blade creates lift. I know airfoil can have something to do with this but some airfoils are more toward the center line of the blade while others are at the leading edge.

    Stability: What characteristic determines how stable the helicopter is at fast forward flight. For example I know that Halos are pretty good at FF flight, and so are rails.

    maneuverability: Some blades roll and flip really well. Others not so well. I am guessing the COG of the blade weight has something to do with this.

    Bigger blades vs Smaller blades on the same helicopter: I dont know why but i am drawn to the biggest possible blade that will fit on a helicopter. It just "FEELS" beter to me..

    Efficiency: What charactoristics make a blade more efficient? Ie: is a particular profile airfoil more suited towards a certain RPM? Some blades mange to provide pop without draining the engine.

    Outer Edge Profile: Does the shape of the outer edge have a big effect?

    All these questions remain unanswered in my head... Does anyone know the answer to some of these questions? Do we have an aeronautical engineer in the house?
     

Comments

Discussion in 'The Chat Room' started by smakmeharder, Feb 4, 2015.

    1. Beaver

      Beaver Well-Known Member

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      I know that an airfoil located toward the leading edge produces better lift, but is better suited to mono-directional applications such as fixed pitch where there is usually no inverted lift needed. A bi-directional airfoil is closer to center and reacts better upright or inverted. It's like the difference between the wing cross-sections of a passenger jet and a fighter or aerobatic jet. (same differences in wing loading and whether or not inversion is anticipated.) One would have to apply more negative collective during inversion with a mono-directional blade compared to normal upright flight in order to make up for the difference in directional lift characteristics.
       
      Last edited: Feb 5, 2015
    2. Beaver

      Beaver Well-Known Member

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    3. Beaver

      Beaver Well-Known Member

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      Stability and maneuverability have more to do with weight and/or rotating mass. A heavier blade or even longer blades will have more rotating mass, especially at higher head speeds and will have more of a "flywheel" effect and be more stable and less likely to buffet at high forward speeds, but response will be slower thus affecting overall maneuverability. a lighter weight blade or a shorter blade will have quicker response due to less rotating mass and less of the flywheel effect, but will be more unstable at high forward speeds. There is a happy medium somewhere in balancing length, surface area, head speed, and weight. A long blade will usually have a narrow cross-section, and a shorter blade will have a wider cross-section. Example: WP_20150204_001.jpg I use two sets of blades on my 120sr: stock blades have more surface area, especially toward the grip where velocity of blade is slower,and they have a more aggressive airfoil. They are light weight and are fairly responsive even considering they are on a FP heli with a mixing fly bar. I use the stock blades when flying outside or in larger indoor areas. On the other hand, I use a set of 200srx blades that are shortened to 1/4 inch (6mm) shorter than stock, pitch was increased about +4 degrees to increase lift just a bit, they are a bit heavier, and have less surface area, which produces higher head speed, higher stability due to more rotating mass (more flywheel effect), but make the heli respond slower. I use the modified 200srx blades primarily for flying indoors in smaller areas where more stability is beneficial.
       
      Last edited: Feb 5, 2015
    4. Beaver

      Beaver Well-Known Member

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      By the way, I'm no aeronautical engineer, so if I'm wrong about anything, feel free to correct me.
       
    5. feral

      feral Well-Known Member

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      Check this vid out from Tim Jones the designer of Cyclone Blades.

      Probably the first video ive seen of any manufacturer on why they designed they're blades a certain way.

      Watch till the end and you'll get to see his famous Beast getting is ass smacked.

      Cyclone Rotor Blades - Tapered Airfoil Technology:
       
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    6. Jeff_Bradley

      Jeff_Bradley Well-Known Member

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      Oh nice work Tim.
      I have never tried them, has anyone had a go with them?
       
    7. feral

      feral Well-Known Member

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      I know Quang loves them he's offered a couple of times to try them id feel slack if I decked them I might have to harden up and give them a crack
       
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    8. smakmeharder

      smakmeharder Administrator

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      Thanks @Beaver and @feral.. Im going to read these really closely - i think there is alot of truth in what you say @Beaver . Thats some good material...
       
    9. Crash Heligod

      Crash Heligod Moderator Staff Member

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      Any helicopter blade that is bent or unbalanced is good..
       
    10. Adam79

      Adam79 New Member

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      Nice video "feral"
       
    11. Beaver

      Beaver Well-Known Member

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      Nice!
       
    12. Jeff_Bradley

      Jeff_Bradley Well-Known Member

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      I have really been enjoying rails (715's) due to their wide code and awesome FF light characteristics. There is certainly a compromise between a blade that is suited for both FBL or FB helicopter set ups. I am yet to fly a blade with both styles considered. I have never tried Cyclones, their design is nothing like anything else so it would be interesting if they cater for all things relative?
       
    13. Beaver

      Beaver Well-Known Member

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      I like the concept behind those Cyclone blades. They seem like a perfect mix of the two sets of blades I use on my 120sr I posted earlier in this thread. We need more innovative thinking like that.
       
    14. feral

      feral Well-Known Member

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      I liked flybar blades on my old trex 500 dfc turned it into a squirrel on crack
       
    15. Mark Mickels

      Mark Mickels Well-Known Member

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      I'm running Cyclone main blades on my Rush 700. They are much quieter than the blades that they replaced. IMO noise=innefficeincy.
       
    16. Beaver

      Beaver Well-Known Member

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      Based on what I've read, they cater to 500 series and up. That being the case, I will have to modify another set of 200srx blades to Cyclone specs for my 120sr, and I'm s.o.l. for my Nano.
       
    17. Manyc

      Manyc Well-Known Member

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      Or just buy a 550 class heli... ;-)
       
    18. Beaver

      Beaver Well-Known Member

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      Easier said than done. I don't have $1000 to spend on a "high end" heli right at the moment...... till then, I'll have my fun experimenting and modding what I have at minimal expense.
       
    19. Manyc

      Manyc Well-Known Member

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      Trex 550 awesome heli... Regret selling mine.. You should pick up a second hand one for 500 with spares
       

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