Gyro-tech carbon fiber blades/RAF

Hey Peter good to hear from you,as you can see Kolibri sidetracked the original article about the blades as usual. My flying time has been

only about 30 hours because of the wind this time of year. The more time I get on them the more I like the way they perform,it seems that

there two things that set them apart from the other blades I have flown is the tip weights and the stiffness of the blades.they are very smooth

and a little quicker in response,and on landing they seem to maintain RPM better and the inertia holds you up longer and gives you a

more predictable landing. Also they seems to ride better in rough air ,the other day I was in wind 18 gusting to 28 and the blades did very well

the one thing I also noticed was that it takes longer for the blades to come off of a high RPM after stopping,I have to be careful about not

pushing the cyclic all the way forward because of the longer RPM decay time.You could tip it over if you are not aware of that.

They are a real quality blade and for the Price are the best buy ever, I will put the quality of the blades,hubbar,teeterblock,and teeter tower as

a very high quality product. Peter Have you been flying your blades.
 
Eddie,

Your experiences with the GT blades have been encouraging. A new set of GT blades have just arrived at the shippers and we will be installing them on a Texas based ELA G8 in the next couple of days. I plan to start a new thread detailing the experience as these blades are a bit of a mystery here in the US.
 
GUYS Back To Topic Please.....Pretty Please.?
 
Frank the topic of this thread is about the Gyro-tech blades on my RAF,the Kolibri (hummingbird ) fellow took it way off topic a long time

ago ,its just now back on track. Anyway I think everything has been said about now the blades fly on my RAF. Thanks for following this thread.
 
I follow this Topic since I was looking at Gyro-Tech for replacement blades for My Hughes 269 I think they are
Bensen B8
 
Hello Eddie, It has been a while since I could fly with the GT carbon blades as we have had so much rain the last month that my runway was inundated with mud patches, I had a 2 hour flight today and oh boy did I get a surprise with the performance and smoothness and no cabin shake or stick shake. I found that on prerotating they spin up much faster to 180 rrpm than the original blades. On landing these blades just want to continue flying.. I set mine up with the shims for high altitude and one up with 40lt fuel the rrpm settles at 340 wit engine rpm at 4250 and cruising at 70mph.altitude 7000ft amsl with a high humidityof 85 %.

Mine is the first RAF in South Africa fitted with GT carbon blades and I am sure not the last. Thanks for your input.
 
spinkaan;n1131910 said:
Hello Eddie, It has been a while since I could fly with the GT carbon blades as we have had so much rain the last month that my runway was inundated with mud patches, I had a 2 hour flight today and oh boy did I get a surprise with the performance and smoothness and no cabin shake or stick shake. I found that on prerotating they spin up much faster to 180 rrpm than the original blades. On landing these blades just want to continue flying.. I set mine up with the shims for high altitude and one up with 40lt fuel the rrpm settles at 340 wit engine rpm at 4250 and cruising at 70mph.altitude 7000ft amsl with a high humidityof 85 %.

Mine is the first RAF in South Africa fitted with GT carbon blades and I am sure not the last. Thanks for your input.

This is great news. Thank you for the flight/performance report.
 
Good to hear from you Peter,We are getting the same rotor rpm as I also am using the high alt shims,I think these blades are probably the best replacement blades

for the RAF, excellent performance at a really good price.
 
I took a look at the Gyro Tech web site; their “gyro” blades are the NACA 8H12 airfoil, the “H” standing for helicopter.

They also list “helicopter” blades of NACA 23012 airfoil section and 7” chord which could be a replacement for Dragon Wings except for price.

They got their airfoils backwards; the NACA 8H12 was intended for helicopter applications while the NACA 23012 was used on the later models of Kellett and Pitcairn Autogiros. But many people also mistake the 8H12 as being a gyro blade because Bensen used it without telling anyone it was designed to be a helicopter blade.

When the first low turbulence wind tunnels came out in the late 1930s, NACA stumbled across laminar flow and to improve the performance of early helicopters, designed a family of 4 helicopter airfoils, the 7H12, 8H12, 9H12 and 10H12. But none of them worked any better than the NACA 0012 when built to full size and run on a whirl tower.

But that’s beside the point; since Eddie and others seem to be pleased with Gyro Tech rotor blades, Gyro Tech evidently have stayed faithful to the proper shape and correct chordwise balance.
 
Thanks for the info Chuck,yes the blades work really well , sometimes why change a good thing when its working just fine.
 
C. Beaty;n1131928 said:
I took a look at the Gyro Tech web site; their “gyro” blades are the NACA 8H12 airfoil, the “H” standing for helicopter.

They also list “helicopter” blades of NACA 23012 airfoil section and 7” chord which could be a replacement for Dragon Wings except for price.

They got their airfoils backwards; the NACA 8H12 was intended for helicopter applications while the NACA 23012 was used on the later models of Kellett and Pitcairn Autogiros. But many people also mistake the 8H12 as being a gyro blade because Bensen used it without telling anyone it was designed to be a helicopter blade.

When the first low turbulence wind tunnels came out in the late 1930s, NACA stumbled across laminar flow and to improve the performance of early helicopters, designed a family of 4 helicopter airfoils, the 7H12, 8H12, 9H12 and 10H12. But none of them worked any better than the NACA 0012 when built to full size and run on a whirl tower.

But that’s beside the point; since Eddie and others seem to be pleased with Gyro Tech rotor blades, Gyro Tech evidently have stayed faithful to the proper shape and correct chordwise balance.

Good morning, Chuck.

I have been in contact with GT about fitting my 'Bee with their blades and they recommended the 8.5" chord at 23 ft. Most blades I've seen for light ships use a ~7" chord but they stand behind that recommendation when I put that question to them. Since I don't know what I don't know, have you had any experience with, or thoughts about, using larger chord blades on a light ship? I am told there are single-seaters with these blades installed and flight reports are favorable. However, data is sparse as is to be expected from a new company, and I would be foolish not to consult others better versed in this subject.
 
No reason why 8.5” chord blades won’t work on a Gyrobee.

RPM and drag will be a bit lower than with 7” blades at usual incidence settings but if incidence setting is lowered to keep RPM up, drag will be a bit higher.
 
I not agree, Chuck
In my opinion, even without change the pitch setting, the drag will be higher than with 7" blades. Because the rotor will have to be heavier for keep the same coning with le lower Rrpm
More you increase the pitch setting for reduce the rrpm, more you need rotor weight . So, the drag still increases
6" would be even better if rigidity could be sufficient. The Mach of drag divergence is still far.
 
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One of the things I like about the 100% carbon fiber blades from Gyro-Tech is the inherent stiffness of the blades,the coning angle appears to

be a little less than other blades I have seen,because of the built in stiffness I like the way they fly.
 
Jean Claude;n1131943 said:
I not agree, Chuck .
My experience is very different, jC. Many years ago, when flying with Bensen type metal blades with adjustable incidence setting, I decided to see what would happen if the incidence angle was set as high as the adjustment would allow.

Top speed was ~20 mph with the stick hard up against the forward stop; more power = climb,; less power = descend. I didn’t have a rotor tach so don’t know the rotor RPM but I don’t recall the rotor vibration as being unusual as a result of coning angle. Other gyro pilots reported similar results with different designs of metal blades having adjustable incidence angles.
 
C. Beaty;n1131949 said:
I don’t recall the rotor vibration as being unusual as a result of coning angle. .
Chuck, I have almost no experience. But that would be like saying that the undersling setting was not relevant.
And If a high coning is not detrimental on a seesaw rotors, that would be like saying we can lighten the rotors to reduce the drag in cruising flight, and to shorten the run at takeoff. Right ?
Sans titre.png
 
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JC, these discussions about rotor vibration are very interesting (to me, at least). Perhaps you are correct; 2/rev vibration is not amplified by resonance.
Cierva’s attempts at jump takeoff used a 2-blade rotor with inclined drag hinges; under the influence of torque during prerotation, the blades would swing back until contacting a stop, leaving the blades at zero incidence. When prerotation torque was released, the blades would swing forward to normal incidence and jump as a result of overspeed.
The problem was that drag dampers slowed down motion about drag hinges and too much energy was lost. Only a 2-blade rotor was free of ground resonance if drag dampers were omitted but Cierva was never able to solve the severe 2/rev vibration problem that resulted.
Then I came along 40 years later, fat, dumb and happy, not knowing any better and built a 2-blade rotor with drag hinges and no undersling, but also, no 2-rev vibration. What happened?
I had acquired a pair of Hughes 269 rotor blades, NACA 0015 airfoil and 7” chord, from an elderly gentleman who had sawn a taper at the root end of the Hughes blades to make them look like Bensen blades.
I thought he had compromised inplane strength so built a rotor with drag hinges and a coning hinge at the center of the hub that resembled a door hinge, the hinge pin also being the teeter bolt.
This rotor was installed on a gyro with mast made from 2.5” diameter x 0.120 wall round 2024 aluminum tube.
There was a bit of ground resonance during rotor start but it never got out of hand.
Much later, ~1989, I built the gyro with tail boom on top and with a rigid, fully triangulated rotor pylon. Naturally, 2/rev vibration was unacceptable.
In my efforts to solve the 2/rev problem, I first tried a rotor similar to my drag hinged rotor but 2/rev vibration was so severe as to be dangerous. Here’s a video of it with drag hinged rotor:
https://www.youtube.com/watch?v=qvdPL1pcG1A
The final solution was the slider rotorhead.

With a Bensen style rotor, most inplane flexure occurs at the hub but if the center is free, there can be no inplane flexure. That’s the reason my soft, round tube mast did not have a 2/rev problem. That is also the reason stiffening the hub reduces 2/rev vibration.






resonance.JPG
 
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Chuck, PLEASE write a book !!!
Brian
 
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