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206 Tail Rotor Question...


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I went and bought "The Helicopter Pilot's Handbook" and came across some rather interesting info reguarding the 206. Here is the direct quote I'm having trouble wrapping my brain around.

 

"The tail rotor is also two-bladed and semi-rigid. Because the bottom blade goes forward, it is a pusher. Large amounts of it can be missing, and you will still be able to fly, either with 50% gone from the end of the blade, or with a big hole in it."

 

Now I can't imagine the tail rotor still staying on the helicopter if 50% of one blade was gone. As for the "big hole" part, I guess it depends on what you call big? If this claim is right could someone help me understand it? Smoke is comming from my ears trying to figure it out. :wacko:

Thanks.

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Ryan,

After careful thought I can only suspect that this author's brain has "large amounts.....missing, and either 50% gone, or with a big hole in it."

 

 

Learn the difference between a pusher and a puller tail-rotor.

Learn why some tail-rotors spin clockwise, and some counter-clockwise.

Learn the advantages and disadvantages of each.

Don't tag your tail-rotor on anything.

Ignore the rest.

Have a banana.

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The author's comments make the rest of the book suspect...

 

Perhaps he's boldly quoting something Bell used in its sales propaganda for its 1960s'ish bid to woo the US Army but I'm pretty sure that the loss of 50% of a blade would cause enough imbalance to shear the bolts securing the T/R gearbox or the T/R shaft. I know of a Bell 412 that lost about 18 inches of one T/R blade while in flight and the gearbox followed shortly thereafter. :(

 

His point about it being a pusher is odd as well. Here's a good site that explains the difference between a pusher (ie. Bell 206) and a tractor (ie. Bell 212) type tail rotor.

 

http://www.enae.umd.edu/AGRC/Aero/tailrotors.html

 

Do you still have your receipt? <_<

 

Keep studying and don't take everything you read at face value. If you can find a copy you should read "Helicopter Aerodynamics" by R.W. Prouty. Fairly technical but well worth the money.

--

Sticky

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Guest sharky

From what I understand, it is desirable for the advancing t/r blade to be travelling upwards, to gain additional airflow from the downwash of the main rotor. This is particularly helpful during hovering.

 

The t/r is also better suited on the side of the tailboom where the t/r wash is allowed to blow away unobstructed-a pusher type tail rotor. Tractor type tail rotor's wash is blown into the vertical fin, creating a 'cancelling' effect, if you will.

 

I stand to be corrected though.

 

One thing is for sure, you certainly don't want to let it come in contact with anything. An acquaintance of mine brushed some small branches on his way into a confined area. He said he felt it right away in the pedals. For the cost of the repair bill, duf could have his commercial licence.

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Elvis -------nahhhh, that's not the reason. They moved it because 'Charlie' always was shooting at us from that side and they wanted to put a tail boom baggage compartment into the commercial version. :D:D:D

 

Seriously though, you are correct..........the whole reason for the move was more complex than that simple answer and really too lengthy for here........but you can take a bow anyways. :D Remember also that the original 205 T/R was just that....and later years updated to what it is now......a 212 T/R in reality.

 

 

I also believe that the author of said book should reply to the original post as he's a frequent visitor here, if I'm not mistaken.

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Indeed I am - the bottom of the blade refers to the direction of rotation - clockwise as viewed from the port side. It's not a pusher just because the bottom blade goes forward - that's just the way I speak - economically. Perhaps I should have said "because the bottom blade goes forward, it spins clockwise viewed from the port side, and because the tailboom is made to go to starboard it is a pusher." Maybe I can rephrase that in the next edition.

 

The Helicopter Pilot's Handbook is not meant to be a treatise on the Principles of Flight - Ray Prouty or Shawn Coyle do that very well already. The idea is to give some practical advice to pilots who are going to get the average training from the average company - i.e. none at all, unless they ask any experienced guys around. Aside from my own experience (which is over 75% of the book anyway), all I've really done is pick up all those bits of paper lying around most offices and put them together as an attempt to impart information - and hey, aside from forums like this there's nothing else. Naturally, I can't verify absolutely everything that I get from other sources, but I do have a good bullshit detector, and information like "flying with a big hole in the tail rotor" has come from someone who has had some experience, in that case from someone who had actually flown in Nam, as reported in a magazine. I don't know how big the hole was, or whether the 50% was actually bullet holes spread all over, but I have no reason to disbelieve people who have been there and done it - and I have learnt to keep an open mind over the years. Richard Bach has flown aeroplanes that have done the seemingly impossible, and many planes in WWII got back with most of their props missing, where you would think that they would have ripped off the gearbox as well, but they didn't. Maybe some readers here should learn to open their minds as well.

 

My point was that the jetbox will stand a lot of abuse and still get you home, which is not to say that you should abuse it. Unfortunately, this is done daily.

 

It doesn't invalidate the book, and comments like those below are completely uncalled for:

 

"After careful thought I can only suspect that this author's brain has "large amounts.....missing, and either 50% gone, or with a big hole in it"

 

"The author's comments make the rest of the book suspect..."

 

Enough pilots with more experience than I will ever have have read the book and said that they wished it was around when they were learning, so I'm not worrying about it, but Ryan can have his money back if he wants, any time.

 

 

And my lawnmower still has 30-odd% of one blade missing :)

 

Phil

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talking of missisng bits of blades . Anyone recall when STARS BK117 had a cowling go though the main blades due to a latching problem , as i recall a substantial section of the trailing edge was missing but they still got it down , I am sure there was lotsa vibration though.

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I've personally seen a 205 land with a couple of feet missing from one main blade. It's not uncommon for a Kamov to lose "pockets" from its mainrotor. I have also seen a 206 that was in the hover ingest a tailrotor gearbox cowling bolt/screw through (and, in fact imbed itself in) the tailrotor... that certainly caused a vibration .

 

I think the point is that helicopters are tough and almost always bring us safely to Mother Earth... I don't think Phil was saying that if you find half your tailrotor missing on your DI, you should finish the day's flying and call maintenance.

 

Also, I haven't read the book and the context is generally very important, so I don't think the "throw the book out" stuff from people that haven't read it was called for (of course I think if you have read it you are entitled to your opinion).

 

HV

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