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Home✈️Aircraft🚁HelicopterBlades and Night Flying › Heli Blades Lengths...in general
05-24-2007 01:27 PM  13 years ago
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timsmith

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Manchester, UK

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Heli Blades Lengths...in general
Hi

I was having an interesting conversation with a friend that Im hoping someone can solve.

The question was originally posed in connection with my Zoom, but is in fact equally pertinent to our other helis.

How much difference does the blade length on a heli make? Is there some ratio that has to be maintained between torque of main blades rotating heli and the torque produced by the tail blades?

I have a Zoom 450 which is proving difficult to get Carbon blades for, but many people make them for the T-Rex450 which is slightly smaller by 10-20mm.

Alternatively, are these blades really smaller, or is it due to different measuring points?

Where are heli blades typically measured from and to?

thanks for the advice.

Tim

Apologies: I guess this should be in the blades forum. If so, can someone please move it...Thanks.
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05-24-2007 02:07 PM  13 years ago
Chopper

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Blades are measured from bolt hole to tip. Longer blades soak up more power, but give a lighter disk loading. The trick is to get a happy compromise between your flying style, the available power, and the available blades.

In general.
Paul Soha is a free agent now. Wow.
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05-24-2007 02:32 PM  13 years ago
timsmith

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Manchester, UK

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Hi Paul,

Thanks for your reply.

When measuring to the tip, is that a point from the blade hole to the tip parallel to the leading edge or the point where the trailing edge meets the tip.

Sorry if Im being thick!!

Tim
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05-24-2007 02:39 PM  13 years ago
gullie667

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Brooklyn, NY

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Also consider the width of the blade grips, bolt hole to bolt hole.

For example, the Trex 450 has a much shorter distance here than the Mini Titan. Therefore, the disk area is larger on the Titan than the Trex given the same set of blades. To get the same disk area as a Titan you would need to run longer blades.

I believe Thunder Tiger did this to create a slightly larger helicopter while giving its customers the freedom to choose from all the killer Trex blades on the market.

Gullie.
Helicopters - 1000 parts flying in formation.
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05-24-2007 02:53 PM  13 years ago
jschenck

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La Vista, NE.

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depends on the manufacturer. there is no set standard of where the 'end of the blade' is. not all 600mm blades are the same length, just like not all 325mm blades are the same length.

that 10-20mm difference from one blade to another is NOT a slight difference. example: 90 size ships that use 690mm blades vs. 710mm blades will have a significant difference in the blade load. That 10-20mm is at the tip where the aerodynamic forces are the greatest.
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05-24-2007 03:40 PM  13 years ago
gullie667

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Provided both manufacturers are measuring hole to tip, the difference is very slight. On a trex blade, 2mm maybe. Even on a 700mm blade the tolerance is still very small. (Not that it doesn't make a difference.)Helicopters - 1000 parts flying in formation.
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05-24-2007 03:44 PM  13 years ago
Chopper

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Stow,Oh- oops, I mean St Louis, nope Stow again,

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Tim, every blade manufacturer seems to measure that differently. SAB and Zig Saw measure the longest point (at the trailing edge.) Other, squarer tip designs measure straight out. Generally speaking though, it is to the longest point from the bolthole, which is usually the trailing edge.Paul Soha is a free agent now. Wow.
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05-24-2007 04:01 PM  13 years ago
jschenck

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La Vista, NE.

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here is an example of where there is a stated 10mm difference in blade length terminology

http://www.heliproz.com/prodinfo.asp?number=802295

Also, IIRC TT600CF's are actually 6mm longer than most other 600mm making them 606mm.
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