“Malo periculosam, libertatem quam quietam servitutem.”
Isn't that how they steer and propel those things? If it didn't wobble, wouldn't it just hover?
The whole rotor head tilts to fly in different directions, up & down is handled by how big a bite ALL the blades take at the same time.The wobble is the blade going up when the helo is going forward, the fwd motion makes THAT blade faster than the blade on the other side, that extra blade speed has to do something so the blades are allowed to flap.How to explain it better... This is all an example.. Say the helo blades are turning at 100mph all by themselves. When the helo is going forward at 100mph that one blade is going forward with both the helo's 100mph AND it's own 100mph, when it gets to the otherside of the rotor head the helo is still going forward at 100mph but now that blade is going backwards at it's own 100mph.The blades are allowed to move where they need to to use up the extra speed because speed = lift and you don't want THAT lift to change what the helicopter is doing.Or that's how I remember it from the Coast Guard Aviation Machinist Mate "A" school back in 1977...
That’s pretty much it. The advancing blade generates more lift than the retreating blade when the helo is in forward flight. The wobble in the horizon here is the blade angle of attack (AOA) relative to the rotor head changing. The pitch change link in the right side of the picture is fluctuating to change the AOA as the rotor spins. Increased AOA, front of the blade up, as the blade is on the retreating side, decreased AOA as it’s on the advancing side. There is vertical flexing in the blade as the changing lift forces act on it. The end of the blade is moving faster through the air than the root of the blade and it generates greater lift. (You can see the same flex in large fixed wing aircraft. Their wingtips start to “fly” before the rest of the wing does and they flex upward.) Igor was on some damn fine stuff when he designed all this. Wish I had it when I was wrenching on the evil things…..
it's called cyclic pitch. the pitch is controlled by a ring that can be tilted left and right, and fore and aft. in theory you move the cyclic control, which tilts the swash plate left and right for steering, and fore and aft for propulsionin practice the cyclic control twitches and pounds and hammers in an area the size of a cantaloupe, and you apply pressure to move the spastic mass more in the way you want to direct the helicopter.helicopters do not fly. they beat the air into submission.
It is a known fact that helicopters are nothing more than a collection of loose parts flying in close formation held together by a combination of something called a "Jesus Nut" (here....you can look it up yourself.) and witchcraft, but mostly witchcraft.Ron tells us...."...The wobble is the blade going up when the helo is going forward, the fwd motion makes THAT blade faster than the blade on the other side, that extra blade speed has to do something so the blades are allowed to flap...."They're telling us, with a straight face mind you, that the blade on one side of the aircraft is going faster than the blade on the other side of the aircraft. So riddle me this, Mr. Sikorsky: At what point does that faster blade catch up to the slower blade? Hmmmm? Like I said....witchcraft.azlibertarian
Dissymmetry of Lift made the early helicopter experiments "real" exciting.Dynamic Flighthttp://www.dynamicflight.com › dissymmetryDissymmetry of lift is the difference in lift that exists between the advancing half of the rotor disk and the retreating half.
ooh ooh - I know that one! A water skier going through a slalom course is going faster than the boat pulling him. same-same.
High cycle metal fatigue comes to mind.
The HH-52 (1950s-early 60s technology) had a fully articulated rotor head, lots of grease fittings as everything moved how it needed to to prevent dissymmetry of lift.The HH-65 rotor head didn't have metal joints & grease fittings like the H-52 did, it had elastomeric stuff, that's not metal, looked like rubber.Everything just bent to allow the blades to fly where they needed to. Kinda different from what I was used to.
I rappelled out of Hueys in the 101st and they vibrated so bad I thought it was gonna come apart.
I spent 3 years with 2/327 Infantry (NFS).
Sometimes they don't work so well.....these cats used up about 13 of their 9 lives that day.https://chinook-helicopter.com/Flight_Fax/1998/Flight_Fax_May_1998.pdf
Fasten your seat belts, it's going to be a bumpy ride.
I feel like I just read the Cliffs Notes on helicopter blades and rotors.
Not witchcraft. Elementary Mr Watson.