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Old 05-26-2005, 10:58 PM   #796
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Hey WeirD, What are the advantages/disadvantages of the number of blades on the rotor? I've always wondered why I see, what looks like, the same type of aircraft with varying numbers of blades.
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Old 05-26-2005, 11:04 PM   #797
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Old 05-26-2005, 11:10 PM   #798
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Pretty cool shot. But I have question, nope. Not a Loaded question (that would
be what clan does the cotton twill kilt belong to?). But how do you fly the
helicopter like that? I assume they're pulling the load for some distance. Right?
I think that some of that is exaggerated by the angle that the picture was taken. I also heard, and I'm not sure if it's true, that the fuel tanks had to be modified to place the pick ups forward enough not to get starved during the mission.

Pulling stuff with helicopters makes for some problematic situations. If the machine gets too forward of the load, then no matter how hard you pull back, the resulting lift vector is not up, but forward and down.
It's called dynamic roll over, or a type of it.

Lets just say that we're good at lifting up, not forward.

Weirdo screwed with this post 05-26-2005 at 11:43 PM
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Old 05-26-2005, 11:11 PM   #799
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Okay, here's my little contribution. AirMed landing at our station for some LZ training. Good folks to work with, Life Flight too.

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Old 05-26-2005, 11:14 PM   #800
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IPulling stuff with helicopters makes for some problematic situations. If the machine gets too forward of the load, then no matter how hard you pull back, the resulting lift vector is not up, but forward and down.
It's called dynamic roll over, or a type of it.

Lets just say that we're good at lifting up, not forward.
Kind of like what happens with the little wire driven battery powered toy

Thanks!
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Old 05-26-2005, 11:15 PM   #801
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Hey WeirD, What are the advantages/disadvantages of the number of blades on the rotor? I've always wondered why I see, what looks like, the same type of aircraft with varying numbers of blades.

What you talkin about.





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Old 05-26-2005, 11:22 PM   #802
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Now yer just funnin' me
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Old 05-26-2005, 11:27 PM   #803
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Hey WeirD, What are the advantages/disadvantages of the number of blades on the rotor? I've always wondered why I see, what looks like, the same type of aircraft with varying numbers of blades.



Fookame I wish that I had a better answer than what it is that I'm going to come up with here.

It all boils down to surface area.

Helicopters that have lots of blades will typically have thin blades, often shorter. Other machines will have fewer blades, but they will be fatter, and sometimes longer. Seems kind of simple, but it's not,

The rotation speed also comes into play, obviously the faster a blade spins the more lift it will create, 'till you have to start flying it forward. So say that the tip speed of a blade it 500 mph, and you want to fly 150 mph. This is where you run into problems.
The advancing blade is at a relative airspeed of 650 mph, getting close to the speed of sound, while the retreating blade is at 350 mph and getting close to stalling at the root (where it's going slower)
So slow the rotor system, but that doesn't help with the retreating stall.
So speed it up, that doesn't help with the advancing blade compressibility stall.

Again

I was on a Bell 214 B1 as a cojo, seat meat, low time kind of guy. The thing had two blades that were 33 inches wide and rotated at a stupidly slow rpm. But my god did that thing lift, and went like a bat out of hell too.

PUI aerodynamics.
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Old 05-26-2005, 11:31 PM   #804
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Now yer just funnin' me
Never.....



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Old 05-26-2005, 11:38 PM   #805
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Never.....

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Are you helping???
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Old 05-26-2005, 11:44 PM   #806
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Are you helping???
You young kids missed out on the adventure.

Vardy and I however......



Ahhhhhhhh..... those were the days.
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Old 05-26-2005, 11:49 PM   #807
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You young kids missed out on the adventure.

Vardy and I however......



Ahhhhhhhh..... those were the days.
Ya whatever. and look who's in the right seat.

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Old 05-26-2005, 11:51 PM   #808
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You young kids missed out on the adventure.

Vardy and I however......

Ahhhhhhhh..... those were the days.
Hiller?
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Old 05-26-2005, 11:53 PM   #809
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Never.....




I get it, medical has a bigger budget than PD so they get more blades

Sometimes WeirD is just too wordy.
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Old 05-26-2005, 11:56 PM   #810
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I get it, medical has a bigger budget than PD so they get more blades

Sometimes WeirD is just too wordy.
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