Gyro Rotor Blades

Butch

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Jun 18, 2020
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67
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Jackson Ca
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Bensen Gyro
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50 hrs
Do you know the manufacture of the blades?
Your description of hand starting them sounds exactly like hand starting Dragon Wings.
They are excellent blades but you need a pre-rotator.
1believe that they are 24feet with 8 inch chord skywheels
 

Gyro28866

David McCutchen
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Dickson, Tn. USA
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Benson B7m & B8m, Dominator II; Kolb Mark III Classic
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From the Original post starting this thread:
as they are aluminum and have no rivets and I am sure that someone could use them
McCutchen Skywheels are NOT aluminum.
 

Doug Riley

Platinum Member
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Jan 11, 2004
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6,586
Right. McCutchen Skywheels are fiberglass skinned. The gelcoat will usually be red, although other colors are/were available. But they aren't metallic on the outside; they're colorful plastic.
 

Countach

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If they have an 8" chord one can rule out almost all Dragon Wings.
 

gyrojake

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E-City, Florida
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Those are Fleck Extruded blades sold by many people in the past.
The last was Rotor Hawk and I believe Anthony of Phoenix also sold them.
They fly very nice once set up properly .
They are very heavy and are a soft alloy like 6063.
I would fly them with no worries
 
Last edited:

JETLAG03

Active Member
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Jul 6, 2019
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france
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300+ flexwing (pendulaire) newly trained on gyrocopter ((autogire)11h)
Blades are 24 feet long with 8 inch chord. Weight with hub bar is about 70 pounds. The weight of my Bensen with fuel is around 290 pounds and I weigh 200 pounds. Here are pics of blades. Can anyone identify? It is telling me that the upload file is too large I will work on it
use Infraview, a free to use program you can resize, cut and modify photos very easily.

Example iphone photo 3000x4000 (approx) pixel size =2148kb
resized to 600x800 pixel = 350kb without noticable loss of photo quality (dependant on photo compostion)

 

Gyro28866

David McCutchen
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May 8, 2009
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Location
Dickson, Tn. USA
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Benson B7m & B8m, Dominator II; Kolb Mark III Classic
Total Flight Time
750 combined FW & Gyro
Hmmm?
From the pictures, it appears that the Hub Bar is a One off Bensen Clone. It also appears that the Hub bar has a Pre-defined twist for the blades.
The Bensen blades had a Pivot point using a Roll Pin, and with a set of "Tracking bars" could be dialed in to precisely the angle you wanted. On my Bensen blades I would set them at 1 3/4* (I think) My tracking bars are 48" long and had a mark of like 1" at 40". Set up like a scissor, I would set each blade the same and they would spin at about 375 RRPM and fairly smooth . I think 1 1/2* produced 400 rrpm and 2* produced 350 rrpm. I think mine were 21' diameter rotor.
That has been 15-20 years since I made them. Memory is a little fuzzy, but it seems like it was calculating the Cotangent of the angle. I would have to do some study to refresh my memory on that one.
If your Hub bar has a built in twist, then I would assume the angular difference between the blades and hubbar would be "0".
but I would want to measure the angle between the rotational center of the hubbar and the blade mount, and determine the angle. This angular difference is your blades "Angle of Attack". As you increase the angle the blades will fly slower to produce the same lift, in other words, turn slower to produce the lift needed for the same "All up weight".
The Centripetal force created by the Rotors RPM is a vital part of this equation. The Centripetal force is generally referred to as "Beam Strength".
If your blades are a set of "Phenix" like Barnys were. I would think you would want around 350 RRPM.
Keep in mind also, as you decrease that air density by either , elevation or altitude or temperature or the combination of these factors, the blades will automatically spin faster to produce the lift needed for the same "All up weight". Blade pitch can be adjusted to produce the desired rotor rpm.
Another reason to go to El Mirage, those folks fly in that density of 7-9 thousand feet all the time.
 

Gyro28866

David McCutchen
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Messages
1,926
Location
Dickson, Tn. USA
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Benson B7m & B8m, Dominator II; Kolb Mark III Classic
Total Flight Time
750 combined FW & Gyro
On a second thought also.
The greater the pitch/angle of attack, the more difficult it will be to hand start the rotor.
 
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