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A video fromm a russian gyro enthusiast.
check the manoeuvrability : steep turns, sideways, very low speeds, very short take off, spot landing.. a gyro has definitively nothing comparable with a UL FW. http://www.rotorwingsportstv.com/russian700.wmv |
Glasgow University have done some work for the CAA on the subject of Gyro stability and control. The main research was into the relationship between the thrust line and C of G. The testing was in a modified 2 seater with an ex mil rotary tp and a PFA gyro instructor/tp doing the flying.
I believe the results proved a link between thrust line and C of G and their effect on stability; particulary the powered push over leading to loss of control. I dont know much more than that I am afraid. Look here for a bit more info: http://www.rogersavage.co.uk/news.htm And here for a useful site: http://www.jefflewis.net/autogyros.html Remember you can never have enough fuel - unless you are on fire. |
Thanks a lot Grey. kind of useful post. It helps to kill some myths.
Victor From the last link : Why Autogyros Weren't Accepted At this point we can ask the question of why autogyros were never widely accepted. Early autogyros, although they had a higher speed envelope than airplanes, had a higher drag and so were not as efficient at higher speeds, and absolutely cound not attain the maximum speeds of the faster airplanes. Also, the early autogyros did not have the vertical takeoff and landing capabilities that would have made them more attractive to potential buyers. When the C.30 finally demonstrated a successful jump takeoff in 1934, it was less than a year until the first successful helicopter flew, and only a few more years until the very successful Sikorsky V.S.300 and VS-316. Although helicopters had a smaller speed envelope than autogyros, they were capable of hovering, and their envelope could fill the role that airplanes couldn't. In other words, anything an autogyro could do could be done by another aircraft. Also, Cierva, who was doing most of the development of autogyros, was funding much of the development on his own. When the army ordered the VS-316, that money went in to Sikorsky's company. This gave Sikorsky the funding for development that Cierva was running out of. Without the money, Cierva just couldn't fund the research. And then, on December 9, 1936, Cierva was killed in normal KLM crash. He was only 41 years old. There were other people developing autogyros, but Cierva had been one of the main driving forces behind the movement. Much was lost when he was killed. Another factor that kept the autogyro from being accepted was purely psychological. Even though helicopters weren't successful until 1935, they had been under development for as long as airplanes. The general public knew about helicopters, and understood the principle of a powered rotor. Autogyros had an unpowered rotor that spun due to aerodynamic forces. Most people did not understand how it worked and so did not trust it. Although it is actually safer than either helicopters or airplanes, people did not realize this. They wanted something powered. |
Can anybody point me in the direction of a production gyroplane/copter with a practical jump-takeoff capability? Do they exist? Are they expensive?
Thanks in advance CRAN :ok: |
CRAN, you'd be well to go and speak to Peter Lovegrove at British Gyroplanes - he's not all that active these days, but has certainly built and tested such beasts in the not too distant past.
G |
Cran,
I am not trying to get gyros over helicos or other. Consider this as a poll. I am amazed of the reactions, i can see a kind of bipolarity. Cran, of course, except some attemps like Groen Brs, Mc Culloch, Barnett., It is evident that the gyros have not been manufactured enough, developed enough, sold enough. But you can't say they don't work because they don't sell. cheers and thank you for your opinion. Gents, Could I abuse and ask some questions : I think that gyros suffer a simple but "old" design. The bensen worked fine but isnt there a way to improve that ? It could be linked to Ultralight Helicopters. 1 - most of the airframes are a classical building, but no modern building has been done. 2 - the rotor is still the old teetering one, couldn\'t a 3 or 4 bladed semirigid of hingeless work better, particularly for the major problem : the Negative G situations. 3 - the blade design are quite very simple, no twist, no taper, no tips. coulnd\'t they be more efficient ? Thanks |
I agree with ShyTorque..luvverly with tzatziki and chips.
Just to be boring again, can they actually hover for a few seconds? |
Rick : yes they can for one or two seconds and can perform jump take off. depending on the prerotation and if they have a variable pitch.
another video link : http://www.lafhelicopters.com/franca...ny/history.htm scroll down and choose the bandwidth |
Amazing Maneuverability...
I have to admit that I was impressed by the maneuverability demonstrated in this video:
http://www.rotorwingsportstv.com/russian700.wmv Much more than I ever thought possible from a Gyro |
RDrickster,
I was (and i still) a helico lover, but i also admit that i had a mental path to admit the gyros manoeuvrability and wether or not an helico is a good choice for an amateur rotor fan... you an fly a rotorhead for 15 000 $ complete, with a ultra light license ... what about an helicopter ?..:rolleyes: Thanks for your honesty . |
An intersting problem
Zeeoo,
This has indeed turned into a very interesting thread! I sat down and had a think about the whole problem yesterday lunch time and came up with some interesting ideas. The reason that I asked about 'jump-takeoff' machines in production today, is simply that I've had a rather neat idea about how to produce an autogiro that can hover for extended periods. However, the problem is that it would require a single main rotor system with collective as well as cyclic pitch. The really neat thing is that the controls would remain completely conventional and intuitive to an autogiro pilot and the machine would not be much more complex than a standard autogyro. There are potentially a number of significant advantages for a recreational rotorcraft of this type: (1) It can hover like a helicopter (2) It's safer than a helicopter (No tail rotor, high inertia rotor, easy to fly, low power requirements at low speed, more stable) (3) It fly’s like an autogiro - always in autorotation (4) It uses a fixed pitch pusher prop, hence allowing engine to operate at various speeds, giving more realistic access to low cost automotive derivative engines [reduced cost]. (5) It can out manoeuvre a helicopter (6) It would be quieter than a helicopter (7) It has better handling qualities than a helicopter (8) Its more tolerant of pilot mis-handling than a straight autogyro (9) Much easier to handle following an engine failure than a helicopter Then considering your three points, you would want to use a three-bladed rotor, with contemporary aerodynamic design as well to further harden the machine against inexperienced pilots. However, with a full helicopter rotor system, big engine and propeller and additional kit for hover capability, are not we heading towards something that would cost about the same as a helicopter anyway? That’s my only concern... If the people who have produced 'jump-takeoff' autogyros, have done so at significantly lower cost than an equivalent weight helicopter, then the concept is potentially useful, but if the cost is equivalent to a helicopter, you would probably be better of with a kit helicopter. Just my thoughts [to stir up the debate - :E :E :E ] CRAN :E NOTE: It doesn't use tip jets of any type, thrust vectoring (other than the MR), or additional lifting props. |
Cran,
on your arguments, i agree. I think you know what i have in mind, and be shure i have considered every comment. The good thing is that we both see what could be desirable to take gyros in another step. bringing the rotor mechanism closer to an helicopter one could increase significantly the cost/complexity.. but not so... You told about 3 blades but a 2 bladed can also be improved (any clue?). The BO108, a heavy helicopter, compared to gyros, flies with a hingeless rigid rotor... couldn't such a system be adapted or copied for a very light gyro ? BTW it could ,maybe, be more forgiving on aerodynamics and use standard dampers (PAULSTRA). examine the latest gyro heads.. they go really close to a small helico one like the mini 500 or the Dragonfly (that use gyro blades)...their price is (approx) between 2000 and 6000 $... Yes, every attempt to have a "hop" capability has increased the complexity. I have a solution to give a hop capability to a teetering rotor at low cost, low complexity. I have a solution to produce a simpler swashplate w/colective/cyclic..drawing are on progress... I think the costs can be lessen by a new variety of offers.. If you can or want, what is your thoughts about that prerotator ? no torque ? no tip jets ? a ducted or oriented airflow ? tip jets are not efficient for a fullpowered rotor, but maybe we could give them a try (i will), mounting a compressor is easier than an hydraulic pump+hydraulic motor (a common solution for prerotating). no torque, the rotor can have a residual power during flight. yes, on this point i still not listen to what very valuable people tell me :} :rolleyes: NB : the Groen Brs use ram tipjets to prerotate, 15 seconds are enough. thank you |
I have found the Jet / Aim / Goodrich/L-3 Avionics range to be reliable and well priced Sperry/AlliedSignal/Honeywell are a little more expensive . Thompson/thales/Eads are french . We were talking about attitiude / Directional gyros weren't we LOL ??
Actually the Thales one probably cost about the same as a low end Autogyro |
Gyros:
Bensen + McCulloch = :oh: (My friend had one but fortunately he's still alive) |
RotorNut,
what could be interesting is YOUR perception of the gyros. Thanks |
I heard that the McCulloch engine usually used in the Bensen was actually an engine designed for target drones, only meant to be used once!
They were a constant headache, but had good power to weight ratio. I suggest that you steer well clear of those old engine designs, however Autogyro´s with Rotax, Arrow or Subaru engines usually work out ok. Its not the engine or the Gyrocopter that will be the cause of the crash, it will be a untrained or reckless pilot! |
Aesir,
You have a large variety of engines available for gyros, from the samller rotax to a IO-360. A lot of amateurs also fit skidoo, moto or small auto engines that work fine. You're very right to say, the main cause of accident is the piloting, not the aircraft or the engine. I should add that an engine out is not a problem in a gyro, a great safety feature. I am curious about how an helicopter engineer could adress a small gyro design.. Thanks Victor |
Hallo Victor
In Switzerland is flying one Gyro only. This Gyro ist hangered in Bex, in the western part of CH. Owner is a member of the FOCA (Federal Office for Civil Aviation). The registration is in France. May be, I find a picture ...... Regards |
I am curious about how an helicopter engineer could adress a small gyro design.. G |
XT244,
thanks for the imput, only one gyro in CH ?? a shame, with the backgrounds you have, a gyro would be , for shure, very pleasant to fly, and safe... i hope you enjoy your B47 BTW ;) Gengis, if i understand, BCAR-T is the equivelent of our UL regulation, isn't it ? If this code is not favorable to gyros, maybe it is not the proper code for that category :confused: i don't know...:confused: I aml currently reading it as i post.. edit : after a quick reading, it is an interesting doc, complete, restrictive but clear.. it looks like it has been made by helicopter eng :D What do you think ? is it a good or bad thing to avoid "experimental" buildings ? amateurs out ! thanks |
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