Georges Chaulet's 200th Autogiro
01-26-2005, 10:01 PM
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Georges Chaulet's 200th Autogiro
Georges has been building model autogiros for well over 30 years. I have an article from him which appeared in "Model Builder" dated in 1977. His latest model, "GIRO 200" displays a couple of interesting technologies. We met him in person for the first time when Emilio Cabezas hosted a fly-in in Madrid a couple of years ago. Georges had
traveled from his home near Paris. Here is a quote from his recent letter:
"The GIRO 200 (the number of rotor-wing models in have built during many years) looks like an autogiro of the classic layout. That is, only an airplane beneath a rotor. However, it incorporates two novelties: the gull-winged blades and the "ROLLTOR" system which provides lateral stability.
"To turn easily, a rotor blade needs to have some helicoidal shape, with a negative angle at the root and flat (zero incidence) at the tip. This can be achieved by carving blades from thick sheet balsa. But that requires considerable time and skill. It is easier after sanding a profile (similar to a Clark Y, but with a sharp leading edge) to partially break each blade at a 45 degree angle in such a way that the middle and tip portions are set horizontally, while the inner segment has a -5 degree angle. To achieve this and avoid completely breaking a blade, first press sown a thin saw blade upon the balsa at the location shown on the plan (dotted lines). then slowly lift the blade for the first fold. When you start to hear a 'crack', stop! This leaves some of the wood fibers unbroken. Repeat for the second fold but with the saw applied underneath and the tip pushed down. Cement is applied at each joint, the blade maintained with weights using a block holding the folds in the correct position and the glue is allowed to dry overnight. (I suppose that some half or three-quarter ounce fiberglass bonded with epoxy covering the joints would add additional stiffness....Billf)
THE ROLLTOR
"This device helps to solve a very complex problem: the lateral stability of an autogiro, which usuallyl tends to bank to port or starboard. My 1993 solultion involved the use of an elastic rotor hub which allowed the blades to flap vertically, a device largely now adopted by autogirists. My new system allows the rotor to bank freely to the side or, the fuselage to roll, without the need of an articulation for each blade. The axle has the shape of an "L". The horizontal rod can rotate about 15 degrees within an aluminum tube which passes through a hard balsa block. An horizontal screw allows the block to rock for the rotor to rock fore and aft. A thin steel arm moves laterally inside a loop which acts as a stop to limit the lateral bank. This system will be the subject of future improvements. (Knowing Georges, we can be sure he will make good on that statement!....Bill)
"The second control is a standard rudder and the third control is, of course, the motor power. A 2C 1500 LiPoly battery is used, providing outstanding gain in thrust and weight saved as compared with standard NiCads. The flight time is around 10 minutes. The motor is an inexpensive 280 with a 4/1 gear reduction being quite sufficient to lift the 11 ounce (320 grams) model.
CONSTRUCTION
"Building is rather siimple, however very light balsa such as might be employed for rubber powered models should be selected. Longerons and uprights are cut from 7/32" sheet. Formers are not necessary. Small balsa blocks are used to wedge the motor in place with -5 deg. pitch down. The stab and the all-moving rudder are flat. To limit the crashes, the landing gear, the rotor pylon and the tail surfaces are maintained by rubber bands. The fore part of the fuselage is sheeted with 1/16" light balsa and the entire model covered with Japanese tissue.
TRIMMING
"Check that the rotor disc (a virtual surface) is horizontal and parallel to the lower line of the fuselage. With the control stick full forward the rotor disc should be inclined by 10 degrees. The center of gravity is 4 cm. (a little less than 2 inches) in front of the rotor axis as shown on the plan. To achieve this balance I increased the weight in the nose by using "heavy" wheels. (That is better than using lead!)
Note from Bill: If the image of the plan below isn't clear, let me know and I can send a better hard copy.
traveled from his home near Paris. Here is a quote from his recent letter:
"The GIRO 200 (the number of rotor-wing models in have built during many years) looks like an autogiro of the classic layout. That is, only an airplane beneath a rotor. However, it incorporates two novelties: the gull-winged blades and the "ROLLTOR" system which provides lateral stability.
"To turn easily, a rotor blade needs to have some helicoidal shape, with a negative angle at the root and flat (zero incidence) at the tip. This can be achieved by carving blades from thick sheet balsa. But that requires considerable time and skill. It is easier after sanding a profile (similar to a Clark Y, but with a sharp leading edge) to partially break each blade at a 45 degree angle in such a way that the middle and tip portions are set horizontally, while the inner segment has a -5 degree angle. To achieve this and avoid completely breaking a blade, first press sown a thin saw blade upon the balsa at the location shown on the plan (dotted lines). then slowly lift the blade for the first fold. When you start to hear a 'crack', stop! This leaves some of the wood fibers unbroken. Repeat for the second fold but with the saw applied underneath and the tip pushed down. Cement is applied at each joint, the blade maintained with weights using a block holding the folds in the correct position and the glue is allowed to dry overnight. (I suppose that some half or three-quarter ounce fiberglass bonded with epoxy covering the joints would add additional stiffness....Billf)
THE ROLLTOR
"This device helps to solve a very complex problem: the lateral stability of an autogiro, which usuallyl tends to bank to port or starboard. My 1993 solultion involved the use of an elastic rotor hub which allowed the blades to flap vertically, a device largely now adopted by autogirists. My new system allows the rotor to bank freely to the side or, the fuselage to roll, without the need of an articulation for each blade. The axle has the shape of an "L". The horizontal rod can rotate about 15 degrees within an aluminum tube which passes through a hard balsa block. An horizontal screw allows the block to rock for the rotor to rock fore and aft. A thin steel arm moves laterally inside a loop which acts as a stop to limit the lateral bank. This system will be the subject of future improvements. (Knowing Georges, we can be sure he will make good on that statement!....Bill)
"The second control is a standard rudder and the third control is, of course, the motor power. A 2C 1500 LiPoly battery is used, providing outstanding gain in thrust and weight saved as compared with standard NiCads. The flight time is around 10 minutes. The motor is an inexpensive 280 with a 4/1 gear reduction being quite sufficient to lift the 11 ounce (320 grams) model.
CONSTRUCTION
"Building is rather siimple, however very light balsa such as might be employed for rubber powered models should be selected. Longerons and uprights are cut from 7/32" sheet. Formers are not necessary. Small balsa blocks are used to wedge the motor in place with -5 deg. pitch down. The stab and the all-moving rudder are flat. To limit the crashes, the landing gear, the rotor pylon and the tail surfaces are maintained by rubber bands. The fore part of the fuselage is sheeted with 1/16" light balsa and the entire model covered with Japanese tissue.
TRIMMING
"Check that the rotor disc (a virtual surface) is horizontal and parallel to the lower line of the fuselage. With the control stick full forward the rotor disc should be inclined by 10 degrees. The center of gravity is 4 cm. (a little less than 2 inches) in front of the rotor axis as shown on the plan. To achieve this balance I increased the weight in the nose by using "heavy" wheels. (That is better than using lead!)
Note from Bill: If the image of the plan below isn't clear, let me know and I can send a better hard copy.
01-31-2005, 03:09 PM
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RE: Georges Chaulet's 200th Autogiro
Gee Bill,
I don't understand why there are no comments about this new concept. This is best inovation I have seen in years for single rotor gyros.
The blades are a little tougher to build but not much & the flapping, delta hinged rotor head is ommitted.
It could be called "deceptively simple".
One item to note though; the rotor mast appears to be a long way aft of the pitch pivot. Or am I viewing the plans wrong.
Thanks for posting Georges' new machine.
Bob G
I don't understand why there are no comments about this new concept. This is best inovation I have seen in years for single rotor gyros.
The blades are a little tougher to build but not much & the flapping, delta hinged rotor head is ommitted.
It could be called "deceptively simple".
One item to note though; the rotor mast appears to be a long way aft of the pitch pivot. Or am I viewing the plans wrong.
Thanks for posting Georges' new machine.
Bob G
