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Old 02-25-2012, 02:45 AM   #5341
Beach40
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Good explanation here:

http://www.helis.com/howflies/groures.php
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Old 02-25-2012, 01:06 PM   #5342
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Worn out tangs, and/or shock absorbers on skids makes A-stars very susceptible to ground resonance. Poor pilotage can put any multi bladed helicopter in ground resonance. A 2 bladed system can not enter ground resonance as the phase relationship of the blades is fixed. They do not have lead/lag hinges.
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Old 02-25-2012, 04:29 PM   #5343
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lead/lag hinges?

You mean you can adjust the rotor blade position as it spins around the rotor shaft? not the attack angle of the blade, but its orientation (1 o'clock, 2 o'clock) etc)?
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Old 02-25-2012, 06:42 PM   #5344
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lead / lag cannot be adjusted in flight, only as a maintenance action to affect the track and balance.

the lead and lag dampers allow the blade attachment some flex as it rotates. Then it is advancing it comes under some load (its flying in to the wind / going upwind) and then as its retreating (going down wind) it doesn't have so much load to these allow them move a bit.

I have some easily accessible photos that I shall try to post up later. I have more but they are old school real film that need scanning, and they are packed away as well.

Helicopters are pretty simple - from the swashplate downwards, its the aerodynamics of the mechanics that is interesting and the limitation of speed.

There is a lot of knowledge on this thread - I am in maintenance tech services and am sure people won't mind if you ask questions. They are not too hard (for me now!) but there are a number of ways of doing the same thing that doesn't seem to occur on fixed wing too much.

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Old 02-25-2012, 07:26 PM   #5345
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Rotor blades on multi bladed systems are allowed to lead and lag to absorb coriolis force do to cg of blade moving in and out as a result of coning.

2 bladed systems are under slung as to cope with this phenomenon. Pick up a basic helicopter handbook from ASA and all this is illustrated in detail and ASA books are cheap.
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Old 02-26-2012, 12:35 AM   #5346
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2 bladed systems will not do this because they are on the same spar, so cant diverge/converge on each other. The "huey" bouncing on the ground is simply a badly set up system, track, balance and trim and you'll have it smooth as an A-Star.
This guy should have just pulled in some pitch and got of the ground then landed it again a little more smoothly. Check out the beginning of McGyver, they left it in the title shot and the pilot did the right thing, door open and all:




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Old 02-26-2012, 12:15 PM   #5347
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Originally Posted by poondogger View Post
Flying will never get old for me.
Who do you fly for?
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Old 02-26-2012, 02:43 PM   #5348
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Quote:
Originally Posted by LemurPilot View Post
This guy should have just pulled in some pitch and got of the ground then landed it again a little more smoothly.

Not the Mcgyver clip - I am refering to the AS350 destruction clip

I dont think there was anybody in it. I didnt see any one get out or blood splater afterwards!
there is a lock for the collective that can be installed to hold the collective down. I think the pilot got out to brief the passengers, open a gate or something. Seems worng and odd but it happens
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Hay Ewe screwed with this post 02-26-2012 at 02:49 PM
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Old 02-27-2012, 08:08 AM   #5349
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Hi!

My apologies if this is 205, but I don't remember seeing this video in this thread. At 43 or 44 seconds in, there's a Green Skyline Agusta. Anyone recognize it? (Weirdo?)

Enjoy,



Liz









Yup, that'd be Skyline. Not sure when, but probably up at Norther Escape Heliskiing. Lot of film crews came and went out of Terrace over the years. Matchstick, Standard to name a couple.

Actually Skyline sold one of the Koalas, got rid of the straight version and kept the KE. I miss flying that thing for skiing, nothing like power to make a guy happy.

Love the vid by the way. Also makes me miss Whistler.......what a second......What have I done to my life?????
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Old 02-27-2012, 08:26 AM   #5350
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Old 03-23-2012, 03:04 AM   #5351
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hey peeps - just a wee headsup


operated flights Brisbane Port Moresby Brisbane on wednesday and then paxed home Brisbane Christchurch n ended up sitting next to a guy we'd flown from POM-BNE...

turns out hes flight ops manager for Pacific Helicopters in PNG (he's based at Goroka) and said they are looking for a couple of pilots.....

Pacific is pretty big up there doing gas oil and seismic work, have a fleet of 212's, AS350's, Longrangers etc.

Pay is pretty good from what I understand (NZD100k n up)...applicants need to have 2000+ hours and be able to handle a 200ft longline from an AS350.....

just trying to help out here folk!



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Old 03-23-2012, 05:52 AM   #5352
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Quote:
Originally Posted by Elvis70 View Post
Rotor blades on multi bladed systems are allowed to lead and lag to absorb coriolis force do to cg of blade moving in and out as a result of coning.

2 bladed systems are under slung as to cope with this phenomenon. Pick up a basic helicopter handbook from ASA and all this is illustrated in detail and ASA books are cheap.
Can we eliminate this problem entirely by going to single blade systems?

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Old 03-23-2012, 05:57 AM   #5353
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Originally Posted by EvilGenius View Post
Can we eliminate this problem entirely by going to single blade systems?


Single blades- Another name for "Fixed wing"
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Old 03-23-2012, 06:13 AM   #5354
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Can we eliminate this problem entirely by going to single blade systems?

They tried that a coupla times, as I recall. Didn't work out so well.
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Old 03-23-2012, 06:26 PM   #5355
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Actually the Germans had a single bladed stationary trainer and even a version that flew. One big blade and a counter balance. No desire to fly it.

http://www.luftfahrtmuseum.com/htmi/ii/i000068.htm
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