RunRyder - Semi- symetrical blades???

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Main Discussion > Semi- symetrical blades???

Ken B
Elite Veteran
Location: Phoenix, AZ

OK, I got this set of 680 Semi Symetrical blades for free. I have never flown Semi symetrical blades before.

What should I expect?

Obivioulsy I won't be doing any 3Ding with them.

Ken B

03-12-2002 Over year old.

HOMEPAGE

BladeRunner
Elite Veteran
Location: Ontario Canada. Member of "some sort" s

Blades?

You can expect terrible-awful things to happen, since I'm your friend just send them to me and don't worry anymore.

03-12-2002 Over year old.

Steve Campbell
Elite Veteran
Location: Baton Rouge, LA

You'll like 'em, Ken. They handle gusty wind nicely, you can eat a sandwich while it's on the way down during an auto, and you'll probably see some improvement in your hovering.

But like you said; leave the upside-down stuff alone...

Steve

03-12-2002 Over year old.

Heli-Driver
Elite Veteran
Location: Arlington, TX

Semis... hmmmm

Hmmm, I've been looking for a set of semi's for my scale 500.

What kind are they? I hear they fly great right side up! And auto like a dream.

Too bad you not stateside, I'd swap you a set of NHP Curtis Carbon 680's for them if they are carbon.

*Sigh* oh well...

Raymond

Predator Gasser SE/231 X 2
Century Helicopters

03-12-2002 Over year old.

HOMEPAGE

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Actually, the inverted performance will depend a lot on the airfoil section. The new FAI stuff that I've just begun to work with requires a stationary six second inverted pirouette (4 sec piro with two 2 sec pauses) at altitude after a pull up to vertical. Using TG 700 mm contest semis, I can easily hold the hover without coming close to running out of negative, and I have no more than 8 degrees of neg in the pitch curve. Mark Christy from England (top FAI pilot in GB) also uses the same blade for some of his demo work. I certainly wouldn't choose a semi section for pure 3D, but you'd be surprised what they can do.

Semi's auto VERY well, often exhibit superior forward flight speeds due to less drag, respond well to gusty conditions, and roll with minimal amounts of required negative pitch.

Ben Minor

03-12-2002 Over year old.

Ray Fernandez
Elite Veteran
Location: Guam (U.S.A.)

Semi Symetrical

I have a set of semi-sym on one of my XCells and I agree with all who stated that they really work well in windy conditions. I have done some mild 3D with them and the blades seem to feather the manuvers well.

Ray Fernandez - GUAM

03-12-2002 Over year old.

Ken B
Elite Veteran
Location: Phoenix, AZ

All,

Thanks for the info, now I'm looking forward to trying them out.

Ken B

03-13-2002 Over year old.

HOMEPAGE

scotter
Senior Heliman
Location: Elkton, MD

Which develop more lift?

I assume Semi's develop more lift? Will the top speed be increased as a result? For example, if I was putting together a chopper for drag racing, would I choose semi's or symmetrical? (everything else being equal)

03-13-2002 Over year old.

KenJ
Veteran
Location: Ohio, USA

If you were? ? ?

If you were to build a drag race machine . . . . . . ., an FAI type blade would work fairly well. That being said, the guy who finished second at a couple of races I attended was using fully semetrical blades I believe.

Another consideration, The blade with the most acceleration does not always have the best top speed.

To make matters worse!!!!!, the blade that is the fastest going straight up (vertical time to climb) may not accelerate horizontally well and may not be the fastest in top speed!!
Very confusing. . . . . . . . .
August 19th, I will have all the test data on my web page.
http://www.geocities.com/kingkenny8

03-13-2002 Over year old.

HOMEPAGE

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

I know of few other topics in which generalities can be so dangerous to make, but most semi's are able to create more lift with a bit lower angle of attack. Such a characteristic can result in faster forward flight speeds and more rotor rpm per unit of throttle due to less drag.

Your butt really goes out on the line when you say stuff like this, though, because a really fat semi section is going to be draggier than a thin symmetrical. I suppose you have to consider averages across all of the blade types on the market.

When we were at the World's, I'm sure Curtis had some of the most powerful engines in the field, but his max FF speed was well below that of Mark Christy and Scott Gray. Scott had a fuse, so he can''t be directly compared to Curtis, but Mark had a fish head CS like Curtis. Curtis was running symmetrical V blades. Mark used TG semis.

I scared to get more specific than this.............I already feel my rear out in the breeze .

.

Ben

03-13-2002 Over year old.

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Main Discussion > Semi- symetrical blades???

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