Gyro Rotor Blades

Butch

Newbie
Joined
Jun 18, 2020
Messages
68
Location
Jackson Ca
Aircraft
Bensen Gyro
Total Flight Time
50 hrs
I loaded up my bensen and headed to Bieber Ca to try out a set of blades that I just had purchased. Bieber has a lot of open flat land and a nice long public runway. The runway is used very seldom and it is the perfect place to practice with very little wind. When I purchased these blades the seller told me that they were a spare set for his benson and that they were new. I took his word for it and it cost me a lot to have them shipped from Florida. When I received the blades I noticed that they were longer , wider and much heavier then my original ones. I am no blade expert so I assumed them to be ok. I posted a question a while back ago asking if 24 foot blades would be ok on a benson but did not get much of a reply. I was exited to try them out and the wife and I headed out. When we arrived it was a beautiful day and I proceeded to unload. The blades were much too heavey for me to lift up on the rotor head so I had constructed a lifting system using a winch. I installed them and proceeded to do my pre flight check. I started up the McCulloch and proceed up the approach to the runway and headed down to the far end. I do not have a pre rotator so I proceeded to try and start the blades by hand. I could barely get them spining at all by hand. Something told me that this was not right. I spun them up as fast as I could by hand which was very little. I thought I would make a slow pass down the runwa to see if they would increase rpm. They gained very little and I know through experience that if your speed is to fast and your rotor rotation is too slow then the blades start flapping with the stick in the back position. I also noticed at this time that with the stick in the rear position the blades were very close to stricking the ground. I aborted everything shut down the motor put the stick in the foward position and waited for the blades to stop. These blades are definately not made for a single place benson. Too bad as they are aluminum and have no rivets and I am sure that someone could use them. I messeged the person that sold me them but have not gotten a response yet. I can not attend the Ken Brock fly in now because I have no blades. I will list them for sale and mabe someone wants them or has a set to trade. I was really looking foward to the fly in especially that the last time I went I was not experienced enough to fly in such a high wind but now I am
 

Barney Bahle

Junior Member
Joined
Jul 25, 2011
Messages
484
Location
Crossville, TN 38571
Aircraft
Rotorway 162F
I can not attend the Ken Brock fly in now because I have no blades.
If I were in your shoes (and I once was) I'd be loading everything up and hauling it to the fly-in. Meet some people that know how to build and set up a machine. Let them go over what ever it is that you have and perhaps they can tell you what you need and where to go from here. Make some friends, learn about gyros, have some fun.

Gerald just so happened to post the video of a machine I rebuilt a few years ago. Proof the advice I give is from my own experience. Take a look. https://www.rotaryforum.com/threads/volkswagen-power.1146487/#post-1181567

Oh, and by the way, the Bensen in this video had 24 foot blades with an 8 inch cord.
 

Brian Jackson

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Jul 17, 2004
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3,283
Location
Hamburg, New Jersey USA
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GyroBee Variant - Under Construction
I loaded up my bensen and headed to Bieber Ca to try out a set of blades that I just had purchased. Bieber has a lot of open flat land and a nice long public runway. The runway is used very seldom and it is the perfect place to practice with very little wind. When I purchased these blades the seller told me that they were a spare set for his benson and that they were new. I took his word for it and it cost me a lot to have them shipped from Florida. When I received the blades I noticed that they were longer , wider and much heavier then my original ones. I am no blade expert so I assumed them to be ok. I posted a question a while back ago asking if 24 foot blades would be ok on a benson but did not get much of a reply. I was exited to try them out and the wife and I headed out. When we arrived it was a beautiful day and I proceeded to unload. The blades were much too heavey for me to lift up on the rotor head so I had constructed a lifting system using a winch. I installed them and proceeded to do my pre flight check. I started up the McCulloch and proceed up the approach to the runway and headed down to the far end. I do not have a pre rotator so I proceeded to try and start the blades by hand. I could barely get them spining at all by hand. Something told me that this was not right. I spun them up as fast as I could by hand which was very little. I thought I would make a slow pass down the runwa to see if they would increase rpm. They gained very little and I know through experience that if your speed is to fast and your rotor rotation is too slow then the blades start flapping with the stick in the back position. I also noticed at this time that with the stick in the rear position the blades were very close to stricking the ground. I aborted everything shut down the motor put the stick in the foward position and waited for the blades to stop. These blades are definately not made for a single place benson. Too bad as they are aluminum and have no rivets and I am sure that someone could use them. I messeged the person that sold me them but have not gotten a response yet. I can not attend the Ken Brock fly in now because I have no blades. I will list them for sale and mabe someone wants them or has a set to trade. I was really looking foward to the fly in especially that the last time I went I was not experienced enough to fly in such a high wind but now I am
Hi Butch.

I would still go if you can. As Barney pointed out this could be a great learning moment with knowledgeable people there to inspect and advise. If Denis of Gyro-Technic is there I understand he lets pilots demo his Razor Blades. Many things could be addressed in one trip.
 

Gyro28866

David McCutchen
Joined
May 8, 2009
Messages
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Location
Dickson, Tn. USA
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Benson B7m & B8m, Dominator II; Kolb Mark III Classic
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If I were in your shoes (and I once was) I'd be loading everything up and hauling it to the fly-in. Meet some people that know how to build and set up a machine. Let them go over what ever it is that you have and perhaps they can tell you what you need and where to go from here. Make some friends, learn about gyros, have some fun.

Gerald just so happened to post the video of a machine I rebuilt a few years ago. Proof the advice I give is from my own experience. Take a look. https://www.rotaryforum.com/threads/volkswagen-power.1146487/#post-1181567

Oh, and by the way, the Bensen in this video had 24 foot blades with an 8 inch cord.
8" chord and 24', all the better for a Fat Boy!
 

All_In

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San Diego, CA. USA
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Piper Archer, Aviomania G1sb
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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
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.
 

Resasi

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Butch, if you can take various photo shots of the rotors, and hub bars, and post them.

I am sure the type can then be identified and better advice then possibly given.

The gross weight of your gyro with you and fuel will then give an idea of rotor length required.
 

All_In

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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
I need to confirm my understanding of what I've learned on this forum about using longer/shorter blades for your all-up weight.
Longer blades is often a solution for heavy-weight pilots.
It is a solution when flying off of much higher density altitudes than where you normally fly from. A few I know have two sets of blades. Many have a different size hub bar.

If a lightweight pilot flies longer blades for his weight. You will float on landings.
If a heavyweight pilot flies shorter blades for his weight. It will be twitchy.

If correct this should help you understand using longer or shorter blades.
 

All_In

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PS:
El Mirage on a hot day is one of the fly-ins I've seen pilots use their 2nd longer hub bar/blades. Even though only about 4K elevation on hot days seen 9K density altitude. A few gyros with one set of blades can only fly in the morning and afternoon. Remember 9K also reduced your horsepower, not just the blades and prop lift.

And if Dragon Wings one post I remember started them by having another aircraft at full power in front of the Dragon Wing gyro that lost its pre- rotator. Then 1st gyro out of the way and used the relative wind as with any hand start.
 
Last edited:

All_In

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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
If too long for your weight can you shorten the hub bar?
 

All_In

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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
If Dragon Wings we can help you start them on a hot day and you may discover they are perfect for El Mirage?
And See Dave Bacon while there. He has installed pre-rotors on Bensens and KB2s for himself and others.
 

Vance

Gyroplane CFI
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Nipomo,California
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Givens Predator
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I need to confirm my understanding of what I've learned on this forum about using longer/shorter blades for your all-up weight.
Longer blades is often a solution for heavy-weight pilots.
It is a solution when flying off of much higher density altitudes than where you normally fly from. A few I know have two sets of blades. Many have a different size hub bar.

If a lightweight pilot flies longer blades for his weight. You will float on landings.
If a heavyweight pilot flies shorter blades for his weight. It will be twitchy.

If correct this should help you understand using longer or shorter blades.
In my experience float on landings is more about blade weight than the length of the blade or the size of the disk.

I have found light blades have less inertia and slow down faster, heavy blades allow you to store more energy in them.
 
Last edited:

Resasi

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And the lift ratio to AUW does effect the handling of the rotors used.

Use too big with too much lift and expect lower RRPM, quicker deceleration of the rotors during landing,, and difficulties in gusty conditions,
 

giro5

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Mar 19, 2006
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Farmington, New Mexico
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prev- citabria,AA1b, fun racer
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I loaded up my bensen and headed to Bieber Ca to try out a set of blades that I just had purchased. Bieber has a lot of open flat land and a nice long public runway. The runway is used very seldom and it is the perfect place to practice with very little wind. When I purchased these blades the seller told me that they were a spare set for his benson and that they were new. I took his word for it and it cost me a lot to have them shipped from Florida. When I received the blades I noticed that they were longer , wider and much heavier then my original ones. I am no blade expert so I assumed them to be ok. I posted a question a while back ago asking if 24 foot blades would be ok on a benson but did not get much of a reply. I was exited to try them out and the wife and I headed out. When we arrived it was a beautiful day and I proceeded to unload. The blades were much too heavey for me to lift up on the rotor head so I had constructed a lifting system using a winch. I installed them and proceeded to do my pre flight check. I started up the McCulloch and proceed up the approach to the runway and headed down to the far end. I do not have a pre rotator so I proceeded to try and start the blades by hand. I could barely get them spining at all by hand. Something told me that this was not right. I spun them up as fast as I could by hand which was very little. I thought I would make a slow pass down the runwa to see if they would increase rpm. They gained very little and I know through experience that if your speed is to fast and your rotor rotation is too slow then the blades start flapping with the stick in the back position. I also noticed at this time that with the stick in the rear position the blades were very close to stricking the ground. I aborted everything shut down the motor put the stick in the foward position and waited for the blades to stop. These blades are definately not made for a single place benson. Too bad as they are aluminum and have no rivets and I am sure that someone could use them. I messeged the person that sold me them but have not gotten a response yet. I can not attend the Ken Brock fly in now because I have no blades. I will list them for sale and mabe someone wants them or has a set to trade. I was really looking foward to the fly in especially that the last time I went I was not experienced enough to fly in such a high wind but now I am
 

giro5

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Well don't know if my reply previously got lost or what but I will say on my kb2 I used 27 ft extruded rotorhawk blades that weigh about 68 lbs as a towed glider. No rotor tack as of yet so I do not know what the rpm of the rotor is. My limited experience is from a 5000 ft elevation paved runway and from a 4000 ft elevation dry lake. Both done in the summer. Found the other reply and deleted it.
 

Butch

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Jun 18, 2020
Messages
68
Location
Jackson Ca
Aircraft
Bensen Gyro
Total Flight Time
50 hrs
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
 

Doug Riley

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Joined
Jan 11, 2004
Messages
6,586
If they are aluminum with no rivets, and weigh a lot, they are likely to be extruded blades. Dragon Wings are pretty light.

You can hand-start Dragon Wings, even long ones, but it's tedious and there's a risk of damage from sudden flapping. A slight breeze helps.

Heavy blades will store more energy than light ones. Stored energy is what enables "float," both on landing and in other flight maneuvers.

The problem with blades that are too large in area for a given gyro is not that they will make "too much lift" -- they are going to make exactly one gyro's worth of lift if they fly at all.

The problem instead is that they turn slowly -- because they don't need to turn any faster to make that one gyro's worth of lift. A very slow rotor will have a lot of stalled area on its retreating blade in normal flight, which will rapidly get worse as the gyro speeds up. The machine likely will be very airspeed-limited, as that stalled retreating-blade area is a big drag-maker.

Chuck Beaty experimented with a very slow rotor and reported that the machine refused to reach normal airspeed; he said it "just screwed itself up and down with changes in throttle."
 

All_In

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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
It's a pain but you have to resample/resize the image to fit the site's photo size limit. IIRC I resample to 10% of the cell phone size to make them upload here.

If you don't have an image editor that will resample them.
Email them to me and I'll do it for you and post.
[email protected]
 

Gyro28866

David McCutchen
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Benson B7m & B8m, Dominator II; Kolb Mark III Classic
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I did a little math, based upon your information, these are the calculations from Chuck Beaty's Spreadsheet
.
24' rotor, 8" cord,
290# + 200# = 490 AUW; 317RRPM and 1.08 disc loading
.
290# + 200# +70#(est rotor weight) = 560 AUW; 339RRPM and 1.24 disc loading.
.
I am assuming that the Beaty spreadsheet is based upon Mean Sea Level and 59*f temperature.
Obviously, as the Density decreases with altitude the RRPM will increase to compensate.
Ernie told me that he likes to see 310RRPM as a minimum on his blades!
A trip to El Mirage and meeting those folks would be well worth your time. with a density of 6 to 9 thousand feet, your rotor might just be perfect for that flying. They will be able to help you get dialed in.
have fun!!!
 

All_In

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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
Brian, there I go again...
I did say the cellphone size and not the resolution the cellphone take a picture at.
Hahahahahaha
 
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