Sv.grainne
Super Member
I'm not confused and Razor Blades (Gyro Technic) were not an option when my manual was published, 2012 version and it states G1SA and G1SB. Will see what Brian finds out from Nicolas.
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Ignoring flight characteristics for a minute, what Nicolas is describing is the mass, and the inherent difficulty in ground handling that will result when maneuvering such a mass on a long moment arm of such a light ship. This is the 'balance of design' he was referring to, and part of my original concern about over-stressing the airframe.Brian, are you sure Nicolas tested the same blades as those you have? Yours are special.
Your rotor is an older type, made for something like a Gyrobee. And you know they stopped building them.
Maybe the single person gyro blades Nicolas tested are of the newer, wider and probably heavier variety?
Don't give up too soon - maybe you have been discussing apples to oranges.
I have a never-used 23' McCutchen Skywheels rotor from 1989 I bought for a single build.
But I'm sure it would be prohibitive to send them back to the US...
Thank you, Kevin.Brian: I'm going to disagree w/ Nicolas. I believe your Gyro Tech rotorblades will serve you fine for a light single-place gyro such as your GyroBee, based on my experience flying several different types of gyroplanes.
My personal opinion is that N.K. is highly experienced in gyro flying, combined w/ his engineering credentials, & armed w/ that combination of smarts & experience found how the Gyro Tech rotors perform for his brand of gyroplanes.
Please don't feel you've made a huge mistake in your purchase. All gyro rotorblades do the job decently. Some exhibit a few traits that you'll notice some differences, such as how long it takes to prerotate them, how the machine climbs & the landing phase.
Some rotorblades, such as the ones made by Igor Bensen, Rotordynes, & the Ken Brock ones, are super easy to hand-start. The Bensen & Brock blades are known as not having great climb performance. Adequate, but some others do better in that category. Chuck Beaty has explained the reason for this many times.
Skywheels are heavier & take awhile to hand-start. It is virtually impossible to do the same w/ the Ernie Boyette Dragon Wings, due to their airfoil design that makes them great performers, but so difficult to get them "over the hump" (blade stall) into enough rpms to start taxiing to feed more air into the rotor disk to have them start speeding up to flight rpms.
I do not have an aeronautical or engineering degree. I've 75 hrs. flying McCutcheon Skywheels (heavy fiberglass construction). Those hrs. were flown using a Vancraft Rotor Lightning. That was my first experience, prior to having dual instruction. Additionally, I have some 250+ hrs. flying Sport Copter's Sport Rotors.
I have one El Mirage flight in my own Sport Copter gyro trying a set of 25' Dragon Wings after hundreds of hrs. under 25' Sport Rotors. W/out any scientific proof, such as accurate measuring, I felt the Dragon Wings might have a shade better climb performance than my Sport Rotors, but that was only a shade in seat of the pants measurement! That same seat of the pants measuring indicated that the DW took a bit longer of a takeoff roll to nurse them up to enough rrpms to hit full power on the takeoff roll. I had no functioning rotor tach to tell more accurately @ which rrpms the difference was.
I & a few others were coached over a CB radio by a fellow PRA chapter member (who had oodles of helicopter time from his Army service, as well as him owning/flying his own Vancraft R.L.), through the extensive balancing on the mains & then progressing to crow hops, & then S-turns flying down the runway using 23' Skywheels.
The Jim McCutcheon Skywheels rotorblades performed well. Very smooth in all phases of flight. They do have a high amount of float when you want to land. Flaring causes the gyro rotors to speed up, creating this float by loading extra energy into the rrpms. Chuck Beaty has explained the reason for this numerous times on this forum. Balanced too far past the 25% chord line is the culprit.
Guys who have flown Skywheels & experiencing the sudden mid-air flare have almost exclusively been in heavier 2-place gyros, such as Steve McGowan's "Black".
Glenn K. in Utah also had the same happen to him in his Butterfly gyro, which is heavier than the light gyros, & didn't have one of those mid-air flairs when he still had a 2-stroke engine as his powerplant. He had switched to the heavier Yamaha 4-stroke engine & was somewhere north of 80 mph when the flair happened.
Don't feel you have made an expensive mistake & have to sell off your Gyro Tech rotorblades, and switch to Dragon Wings or Gyro Technic ones, because you fear that you'll crash while flying them because they exhibit dangerous characteristics. That is something you might wish to do later, after you've mastered solo flight & have time up flying your GyroBee.
The fools who take off prematurely b-4 the rotorblades are up to flight speed by horsing their gyro off the ground (like one rotates an airplane @ a certain A/S), & are too nose high flying way behind the power curve, deserve the results their impatience brings. All of that is covered by a CFI's instructions & demonstrations. A gyroplane tells the pilot when it is ready to fly, not the other way around. We're not flying Beluga whales here!
Again, my opinion, your Gyro Tech rotorblades will do just fine for your GyroBee. Trying different rotors after you've become proficient in all phases of gyroplane flight will come naturally.
I'm sure they were different blades, but I did reply back asking which rotor he tested. Hopefully his kindness continues while I'm pestering him for data. I can't expect someone to drop everything to answer questions for a non-customer. But here is my reply to Nicolas. Will post response when he is able.Brian, are you sure Nicolas tested the same blades as those you have? Yours are special.
Your rotor is an older type, made for something like a Gyrobee. And you know they stopped building them.
Maybe the single person gyro blades Nicolas tested are of the newer, wider and probably heavier variety?
Don't give up too soon - maybe you have been discussing apples to oranges.
I have a never-used 23' McCutchen Skywheels rotor from 1989 I bought for a single build.
But I'm sure it would be prohibitive to send them back to the US...
I received a test set of blades from Gyro Tech Poland. They were suppose to be a direct replacement for the helicycle aluminum blades. Due to the way they are constructed the blade span balance was off about 10 inches from what the stock Helicycle blades were. The blade is normally tail heavy so they overbalance it at the tip to compansate. They gave me a report of the changes that would need to be made to the rotorhead to make the blades work. I informed them they suppose to be direct replacements. they are now going to build up another design the suppose to better match the aluminum blades. I think it may be the same on a Gyro any different weight distribution on the blades would require changes in teeter height and cone angle.I'm not confused and Razor Blades (Gyro Technic) were not an option when my manual was published, 2012 version and it states G1SA and G1SB. Will see what Brian finds out from Nicolas.
All aluminum with the exception of the sky wheels. the old school way of making blades is that they need to balance at 25% through the entire length of the blade. new school composite seems does not matter what the chord balance is we can just overbalance it at the tip to get 25% that works as long as the rotor head is designed for it.For those interested, I was able to quickly locate the pertinent info from Ralph's GyroBee documentation. I've highlighted (in bold) the bits related to the recent discussion:
___________________________________
Rotor Blades
Rotor blades are critical with respect to several aspects of the Gyrobee, including performance and legality. The Gyrobee has been flown on all the blades listed below and I have included some notes with respect to each option:
Dragon Wings
Current production Dragon Wings (those with a reflexed trailing edge) are very light and fly the gyro very well. Unfortunately, they cannot reliably hand-started so a prerotator would be required. Fortunately they are light enough that you could add a basic Wunderlich prerotator and keep your machine Part 103-legal with respect to weight. The top speed of your machine may exceed 55 knots (63 mph), but weight is a bigger issue with respect to Part 103 than speed (within reason!). A 23-foot rotor disc is adequate with these blades.
Sport Copter Blades
These are very smooth blades and, while not quite as efficient as the Dragon Wings, they do a fine job. They will hand start but are light enough that a prerotator may be legal. Good performance would mandate the use of a 24-foot rotor disc.
Rotordyne Blades
These are solid blades that hand-start easily. Unfortunately,they are too-heavy to permit the use of a standard prerotator. A 25-foot rotor disc would be optimum with these blades.
Rotor Hawk Blades
These blades are more difficult to set up initially, but will provide adequate performance on a 24-foot rotor disc and hand-start easily.
Brock Blades
These blades are light and hand-start very easily. There is enough of a weight margin for the use of a prerotator. Performance is adequate with a 24-foot disc but the blades do not conserve energy well. As a result, you get essentially one chance to execute your round-out before the blades play out.
Sky Wheels
These blades will perform well in the 24-25-foot range but the blades are so heavy you may not make Part 103 weight.
Rotor Disc Diameter
The major problem early in the flight-testing of the prototype was how to get a good climb rate when using blades of moderate performance and an engine of only 40 hp. Fixed-wing ultralights solve the problem by having a relatively high wing area for their weight, resulting in low wing loading. The solution with the Gyrobee was similar -increase the diameter of the rotor disc to improve the disc loading. The typical single-seat gyro flies at a disc loading of 1.2 to 1.4 pounds/square foot (psf) with engines in the 65-90 hp range. In the case of the original Rotordyne blades, we used with a 5 foot hub bar, producing a
25 foot rotor disc and a disc loading of about 1.0 psf. This produced excellent performance yet the aircraft could easily be flown in winds up to 30 mph,assuming a reasonable level of pilot experience. The ten-foot Brock blades were lighter and were flown with a 4 foot hub bar, producing essentially identical disc loading on a 24 foot rotor disc. The tall mast provides ample rotor clearance in either case. Although the aircraft will fly at a disc loading of 1.2 psf, I do not consider the climb performance margin acceptable. Rotor disc diameter for the various blades options listed above has already been provided.
This discussion is precisely the sort of debate, and information exchange that is entirely appropriate in this thread Brian.By the way, I'm sorry if I've hijacked this thread from the OP. Just seemed a good place to have this discussion. So glad our Rotary Forum is still here.
Wholly agreed.This discussion is precisely the sort of debate, and information exchange that is entirely appropriate in this thread Brian.
It is valuable information that is being shared for the benefit of all of us, and I heartily endorse the gratitude we all feel to Todd for the continuation of the Forum.
Hi Wolfy.I think they will be fine Brian, to me a disk loading of 1.1 is near perfect and lets a gyro fly like a gyro should.
There won't be a huge amount of extra float on landing because the light disk loading means a slower rotor rpm (it will still be well within spec) which also means less energy retention.
With the extra weight up top you should always taxi with rotors turning a decent rpm, I won't taxi anywhere without rotors turning and the rougher the ground the higher the rpm.
wolfy