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Old 05-17-2016, 04:52 PM   #126 (permalink)
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Originally Posted by Crisbee1 View Post
Hijacks Too...
This thing is badass, counter rotating ridgid rotor and a propulser.
Waiting to get tapped to fly a half scale in the Ames 40x80.
That would require a turntable rotating at a speed such to cause a downforce from the counter rotating blades eqivelant to the upforce from the other rotor while on a treadmill going the same rate as the propulsor.
i know you can't equalize the force as the rotor spinning the same way would continue to increase lift as the turntable spins faster

Last edited by JunkCJ6; 05-17-2016 at 04:55 PM.
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Old 05-17-2016, 04:53 PM   #127 (permalink)
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And -5 pirate points for bringing up rotor speed relative to the fuselage as a mode for lift.
You fail harder than Narrock.

I did not say it was the mode for lift. I am saying that the thing that is making the rotor turn (effectively the fuselage as the gearbox driving the rotor is fixed to it) is turning just as fast as the fuselage but just opposite. They are dependent on one another and thus they cancel each other out, so the rotor is not moving relative to the ground. It is moving relative to the copter but not to the ground.

Its kind of like how in the movies you see the wagon wheel stop spinning because the rotational speed is the same as the frame rate of the film.

Or like when you run on a treadmill. You are moving forward at some speed and the treadmill is moving opposite it at the same speed. That is why you don't go anywhere.
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Old 05-17-2016, 04:54 PM   #128 (permalink)
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So the main blades wouldn't be moving in relation to the ground,
but the fuselage will be spinning like a m-fer?

I'm going to go with no.
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Old 05-17-2016, 04:55 PM   #129 (permalink)
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Or like when you run on a treadmill. You are moving forward at some speed and the treadmill is moving opposite it at the same speed. That is why you don't go anywhere.
But what if you have a fan blowing on you like a headwind?
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Old 05-17-2016, 04:55 PM   #130 (permalink)
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So yes. IF the is rotor is pulling collective and the fuselage is creating lift. And there will be no torque if they are equal

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Old 05-17-2016, 04:58 PM   #131 (permalink)
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Which DJ is manning the turntable?
Z-Trip.
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Old 05-17-2016, 05:00 PM   #132 (permalink)
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But what if you have a fan blowing on you like a headwind?
well you are not rigid relative to your feet, you can bend backwards. If the headwind is enough to overcome your core muscles and cause you to lose balance and fall back, then technically you are moving, but that is not the case where the rotor shaft is rigid to the fuselage.
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Old 05-17-2016, 05:11 PM   #133 (permalink)
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Originally Posted by non-OP View Post
You fail harder than Narrock.

I did not say it was the mode for lift. I am saying that the thing that is making the rotor turn (effectively the fuselage as the gearbox driving the rotor is fixed to it) is turning just as fast as the fuselage but just opposite. They are dependent on one another and thus they cancel each other out, so the rotor is not moving relative to the ground. It is moving relative to the copter but not to the ground.

Its kind of like how in the movies you see the wagon wheel stop spinning because the rotational speed is the same as the frame rate of the film.

Or like when you run on a treadmill. You are moving forward at some speed and the treadmill is moving opposite it at the same speed. That is why you don't go anywhere.
The thread is about lift. Rotor speed in the air is lift. Yes, the fuselage of the helo is what's it's turning against.

Unlike Narrock, I can reread your post and see that I misread it. So kiss my Narrock.
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Old 05-17-2016, 06:38 PM   #134 (permalink)
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Nope, unless the tail rotor is strong enough to over come the friction of the skids and the turn table.
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Old 05-17-2016, 06:45 PM   #135 (permalink)
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Nope, unless the tail rotor is strong enough to over come the friction of the skids and the turn table.
We get a tail rotor? if we get a Tailrotor that means there will be a gearbox which will be turning at twice it's normal speed, yard sale...

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Old 05-17-2016, 06:52 PM   #136 (permalink)
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The thread is about lift.
It's not the french door thread?
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Old 05-17-2016, 06:57 PM   #137 (permalink)
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Can we just mount the helicopter upside down and attach the rotor to the ground so we don't have to have a turntable?
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Old 05-17-2016, 07:09 PM   #138 (permalink)
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Can we just mount the helicopter upside down and attach the rotor to the ground so we don't have to have a turntable?
That would just be a carnival ride at the fair.
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Old 05-18-2016, 07:45 AM   #139 (permalink)
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And you are incorrect on your last point, perhaps. A cyclic input of anything other than neutral would produce the blade quivering effect. A collective input (typically referred to as 'pitch') would not produce this effect, you would simply see the stationary blades move to a high pitch. However, depending on what exact type of rotor system and rotor dampening system was in place, the blades may see some other pitch effects. Aerodynamic forces are also critical in allowing some control operations, and I am sure there would also be some undesirable effects from that.
This shows my ignorance of helicopters. I was talking about changing the angle of the axis of rotation of the main rotor so that it is no longer coincident with the axis of rotation of the turntable.
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Old 05-18-2016, 07:50 AM   #140 (permalink)
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Originally Posted by OverThrottle View Post
If same speed but opposite, they should cancel out and the rotor would be motionless.
Spoiler.

Now, if the turntable was spinning in the SAME direction, would it take off twice as fast?

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Old 05-18-2016, 07:53 AM   #141 (permalink)
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which turns at the same speed in the opposite direction of the spinning main rotor.

Will it take off?

depends on how idled up the rotor is.
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Old 05-18-2016, 07:54 AM   #142 (permalink)
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So, there's a tornado in a hurricane spinning the opposite direction. Does Dorothy take off?
No, Dorothy gets blended.

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Old 05-18-2016, 07:57 AM   #143 (permalink)
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Originally Posted by Beat95YJ View Post
It's an idealized test. It could not be done in the real world. The "parameters" are equal and opposite rpm. That's what you need to consider for this round of mental masturbation.
Indeed.

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Old 05-18-2016, 08:11 AM   #144 (permalink)
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Not the same thing. Not at all.
go look at the physics of twin rotors. if you understand how they work, you can understand why the blades will not be stationary relative to the ground

why do you need a tail rotor or ducted fan on a helo?

besides stability and "steering", it's there to keep the fuselage from spinning which direction?

the main rotor instills small counter-rotational force on the fuselage. the frame reference is the air around (due to create lift). if the main rotor imparts small counter-rotational force on the fuselage, then the reverse must be true. the fuselage has little effect on the rotation of the main rotor. then what is the mechanism or force that keeps the main rotor stationary relative to the ground?
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Last edited by paragon; 05-18-2016 at 08:17 AM. Reason: edited out some nits
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Old 05-18-2016, 09:52 AM   #145 (permalink)
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go look at the physics of twin rotors. if you understand how they work, you can understand why the blades will not be stationary relative to the ground

why do you need a tail rotor or ducted fan on a helo?

besides stability and "steering", it's there to keep the fuselage from spinning which direction?

the main rotor instills small counter-rotational force on the fuselage. the frame reference is the air around (due to create lift). if the main rotor imparts small counter-rotational force on the fuselage, then the reverse must be true. the fuselage has little effect on the rotation of the main rotor. then what is the mechanism or force that keeps the main rotor stationary relative to the ground?
Engineers be all missin' the entire simple point of the OP by over thinking it....


Edit: fuselage be spinning 500 rpm counterclockwise and the rotor is spinning 500 rpm clockwise in relation to the fuselage, what is the airspeed of the blades?
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Last edited by 300sniper; 05-18-2016 at 10:01 AM.
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Old 05-18-2016, 10:00 AM   #146 (permalink)
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Edit: fuselage be spinning 500 rpm counterclockwise and the rotor is spinning 500 rpm clockwise, what is the airspeed of the blades?
Above or below the equator?
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