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HelicopterBlades and Night Flying › Product Evolution (MAH)
10-23-2004 09:08 AM  13 years agoPost 1
Vernon Barrett

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Kansas City MO

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Product evolution is a very powerful thing when it comes to the products you use. No one I know uses a mechanical gyro because they have been introduced to a soild state technology even though it does vibrate. This technology has set new standards that all pilots have come to expect when purchasing a gyo. Even the radio's of today have become indispensable in their capabilities. I can remember having an Applo radio that I had to use dip switches to reverse the servos, no LCD screens here.! There isn't much of a market for such a limited low tech radio these days. Just as wood blades were in high use back then for all sizes. Today carbon or composite blades seem to dominate. Sometimes new technology doesn't seem as evident as you would think. Most often it's guise may appear gimmicky or just as twist on an old idea. That twist as it were can make a huge difference in performance.

I started with flying RC planes and I remember the first time I saw as APC prop. I thought what a silly looking prop this is. Well anyone of you that are familiar with planes too should know that the unique shape of the APC prop is what gives it it's edge over all other prop's. At the NAT's 99% of the top ten finishers used this unique propeller design. Some of the key elements of the propeller design are that it's leading and trailing edges are curved. That is because the air will travel in an arc as it is accelerated to the tip. The blade is also highly tapered and the tips are washed out.

Often in the development of an aircraft models are the first to be built as proof of a concept. With positive results gathered for the model a full version is then built. I would like to make the same comparison between the APC prop and the MAH blade being a scaled up vaiant. Both are highly tapered and at speed all blades have some degree of washout. The only elements that they don't share is the curved leading and trailing edges and airfoil profile. One other aspect of the Mah blade that most people neglect to realize is the power savings they get buy using them. Just as the MP2 vs a muffler with one you'll get some extra power to use as you like. The same holds true for the Mah blade.
It will offer you some extra power to do as you like.

Before the brigades of bashers come fourth I will say this. My purpose and hope is that all pilots will come to expect more from the blades they use from a design point of view. I know we have all dreamed about future features on our radio's or about leaps in battery capacity. My expectations run high for blade designs. What I hope for is for more choices and more technology. Part of the appeal of model helicopter is that they are not simple little machines and anyone able to fly one has really accomplished something. It is also my purpose to point out the successful application of a tapered airfoil (APC prop) and that a scaled up version can benefit us all. But that is only possible if we can make the connection to it's design attributes as it applies to helicopters. This is one instance were taking a page from our fixed winged brothers wouldn't hurt. As they have found an effective and efficient way to move air! Sometimes that proof of technology is right there in the pits.

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10-23-2004 09:18 AM  13 years agoPost 2
DOKEY

rrProfessor

Northamptonshire UK

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So your saying design a blade that uses the design features of an APC prop ?

Has'nt this been done already by Robbe and partly by NHP, and maybe others ??

Ryan.

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10-25-2004 05:47 PM  13 years agoPost 3
gamberopiloto

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Vancouver BC

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The only elements that they don't share is the curved leading and trailing edges and airfoil profile.
Vernon,

You would gain two advantages with this design that I can see, first would be in shear lift capability (case in point the Osprey) second would be in speed. The draw back would be in 3D flight, because you would not have the same advantage with the A/C inverted (negative pitch) this design would be counter productive. Take a look at constant speed props on full size A/C. The ability to produce negative pitch is there but is it usable for more than slowing the A/C? I'm sure an engineer could explain it in more detail. I do agree that there has to be evolution on the horizon, but the way in which R/C helis CAN fly sets a new benchmark where civil aviation hasn't truly ventured.

Nape

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