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02-07-2006 03:34 AM  12 years agoPost 1
Dwight

rrApprentice

West Chicago, IL

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I have posted some pictures of blades in my gallery. The point of these pictures is to show how the CG of blades vary. One of the pictures shows an aftermarket blade (carbon fiber) that has a very poor CG compared with the stock woodys. There are a couple of pictures where I moved the weight of the blades from the tip to the root. Using the same amount of weight at the root the CG was improved by a significant amount. Even though this does not look like much the CG of the blades makes a machine much smoother as the feathering is more on the bolt pivot hole.
The moral to this thread is that just because the blades are nicer to look at does not mean they will fly better. I suspect that many of the small helis flying today have blades with poor CG. This has a significant effect on the twitchy feel in the controls.

Dwight

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02-12-2006 12:30 AM  12 years agoPost 2
shesha

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Kuwait

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IMHO, it's more workmanship related then material related.

Zero bubble....

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02-12-2006 03:48 AM  12 years agoPost 3
dkshema

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Cedar Rapids, IA

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The twitchyness (is that a real word?) can easily be caused by the CG location of the blades. It's not always a build problem.

In larger helis, people refer to blades with an aft CG as being "agressive", meaning they react quickly to control changes. They are lively blades.

Dwight knows how to build and he knows helicopters. He's a world class heli competition pilot, and has been working with Kyosho for many years, helping to develop their helis.

Dave

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02-12-2006 08:01 AM  12 years agoPost 4
shesha

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Kuwait

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Have question related to woodies, on several occasions I noticed that the "clear shrink wrapping" if you can call it that, tend to be badly shrunk, if thats the terminology, ignoring them I installed them on the heli resulted in execessive MR lead and lag situation and sometimes execessive vibration.

Weighing them and cging if thats the correct word for MR blades, did help but did not get them to run 100%.

Inspecting them again showed that the excess plastic shrinkage at the end of the blades broke open.

I sanded the excess down, and rebalanced as best as I could still had issues with them, I decided to drop them back at the LHS who were kind enough to swap them with another set.

Also on one occassion I had issues with the plastic blade holders where the main MR bolts go in, they were slightly thicker then normal, they just would not fit into the grips, without applying pressure or trying to wiggle them in, to make matters worse, the bolt had problems sliding into the plastics holes.

Lesson learnt, inspecting the woodies at the LHS prior to buying them if you can. Saves you thr trip back.

No such issues with mavericks as of yet.

Zero bubble....

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02-15-2006 10:57 AM  12 years agoPost 5
BARTGALAMBOS

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Huntsville, Alabama! U. S. A.

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Koll Rotor Pro and Gram Scale.......
Hi Folks,

I use the Koll Rotor Pro and Gram scale and Balance each set to match, both along the chord and span.

I had only one set of blades that matched without adding some lead. Most blades are off along the chord, and it takes a lot of lead to correct this. However, once I balance the blades they are smooth as silk. Then any oscillations tend to be produced by engine tuning techniques, which to me are more of an art!

Bart

Precious Metal Investor!!!

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02-15-2006 02:07 PM  12 years agoPost 6
Dwight

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West Chicago, IL

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Bart,

I am not sure if your post is supposed to be relative to the original post or you are describing your process. My point is not that blades vary within a given set but that the lead/lag cg varies greatly between different types of blades. This can have a significant effect in performance as the further back the cg resides the more aggressive the blades become.

Dwight

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02-15-2006 02:59 PM  12 years agoPost 7
BARTGALAMBOS

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Huntsville, Alabama! U. S. A.

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Sorry Dwight,

when you say furthur aft, I take you mean along the span towards the root, or aft along the chord?

Bart

Precious Metal Investor!!!

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02-15-2006 03:32 PM  12 years agoPost 8
Dwight

rrApprentice

West Chicago, IL

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If someone is talking about fore/aft or lead/lag that refers to chord balance or chordwise cg.

If you look in my gallery of pictures you may see the point I was making. It shows a wood blade compared to a carbon blade and two wood blades with the same amount of lead moved to a differnt position along the leading edge and how it changes the lead/lag. It shows that you can correct the leading cg of a blade more by adding the lead to the root without creating a tip heavy blade. I did not give a full description of the pictures but in the picture of two wood blades the one in the foreground has the lead moved to the root whereas the one in the back is at the tip. You can see in the picture where the lead was. This has shifted the chordwise cg about 3/16 inch. If you think about adding lead to a blade most people want it for stability. I was showing that it can be and is used to correct chordwise cg.

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