View Full Version : one for Dave Jackson.
bugdevheli
15th Dec 2006, 21:40
Dave Rotor blade with hydraulic vein labrynth under skins, permitting blade pitch changes at any required point along its length! No swash plate . Bug
Graviman
15th Dec 2006, 21:50
Or an electric motor near the hub to vary blade twist as a function of airspeed. Design blade taper to run at zero twist at Vne so that retreating blade does not suffer unpleasant lift distribution...
Mart
bugdevheli
15th Dec 2006, 22:02
I mean variable as a birds wing. ie.the ability to vary pitch and blade contour where necessary. Bug
Graviman
15th Dec 2006, 22:19
Bug,
Interesting thought is that once you accept fly-by-wire there is no real reason to use a swash plate. There would need to be a very reliable transducer for azimuth, and ideally a very simple non-programmable computer (so that it can't crash). If power is supplied to rotor via brushless AC transformer (not slip rings), then you could have a number of electric actuators continuously adjusting pitch.
A safer solution is to use swash plate and motor trimmers for more efficient flight. This improves rotor aerodynamics, but allows a safe back-up in the event of electrical failure. Hydraulics are starting to give way to electric servos in all industries. Then again you could probably get 95% there with seperate tip and root swashplates (or spider) - it would just take some careful packaging.
Mart
Dave_Jackson
15th Dec 2006, 22:24
bugdevheli,
Not bad. Looking back to see how nature and evolution work. How Darwinian. :ok:
A concern. Would the centrifugal force cause the hydraulic fluid [blood] to flow toward the tips and cause the blades to go stiff [get an erection]? Maybe tooo Darwinian. :uhoh:
Dave
bugdevheli
15th Dec 2006, 22:55
Dave following your observations regarding the comparison of hydraulic fluid to blood i can now confirm, (having sat in the spin dryer to test your theory), any outlying appendage does appear to suffer from peniserectus. Having discovered this i have lost all interest in rotor blades and im off to bed Thanks Bug
... there's always memory plastic...
Graviman
16th Dec 2006, 09:53
I was under the impression that for some rotor blades the centrifugal force acting on the internal air plays an important part in blade structure. If the tip is running near mach 0.5 in hover, then you could generate a few hundred mBar. This internal pressure can help reduce the required blade material thickness for a given stiffness.
Having just opened the flood gates for double-entendres...:rolleyes:
Mart
.... not sure if "flood gates" is the best choice of phrase...