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NOTAR Systems

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NOTAR Systems

Old 18th Jul 2001, 09:08
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Question NOTAR Systems

To all,

Never mind what was posted here, it seems that since im only 17 i know nothing
Cody

[ 22 July 2001: Message edited by: Copter Cody ]
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Old 18th Jul 2001, 13:39
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show us the statistics
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Old 18th Jul 2001, 15:00
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Unhappy

notars are very quiet. really fantastic! and i myself had the pleasure of flying a corporate md600n for half an hour. it felt like flying a BIG h300 or a very fast enstrom f28, because of relatively large pedal inputs needed throughout a flight. no hydraulics and the pilot used to fly it with the four-way electric trim - although i was taught "never to fly the aircraft with the trim." the six bladed fully-articulated rotor system was very stabil and gave almost no vibrations. it was like floating (on a cloud) through the air. only problem, the pilot told me, autorotational airspeed is 85 knots. that doesn't give you much for a 180 deg turn if you need it. think about that, the 206b has 52 minimum in the handbook. i know optimum airspeed is a lot lower, but still.

now, little gossip from mexico city: the md-team was in mexico city to demonstrate the 600 performance. the helicopter came in for landing on a pinnacle, a building. as you might know, mexico city is located around 8000'. when the pilot ran out of left pedal pulling in power, the helicopter made at least a 180 degree turn by itself over the pad before the pilot was able to set it down. the demonstration flights were limited to a half hour radius and little weight inside the cockpit, to maintain positive control.

anyway, that last story might just be rumours, so don't sue me, i'm still broke after heli training!
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Old 18th Jul 2001, 22:20
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The exact same thing happened to a Navy pilot many years ago whilst trying to fly an approach to a ridge in South Georgia unfortunately a few years later an army pilot managed to do the same thing in Saillagouse killing the crew in the process. Funny how pilots always pay more attention to Density Altitude and Weight and power limits after the event. If it really were the MD team demonstrating their machine then frankly they need their a**** kicked. IMHO of course.
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Old 18th Jul 2001, 22:41
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If you are really interested in the truth..... contact [email protected] he was flying and the story told here is not even close!
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Old 18th Jul 2001, 22:52
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Good Ol cody is now a NOTAR expert!!!null
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Old 19th Jul 2001, 08:52
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AbnerPilut-

What dp you mean by that?

Cody
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Old 19th Jul 2001, 10:10
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After a slight technical hitch........
1) I believe that the Notar system is now about 10 years old.
2) The reason that 'you haven't had the pleasure of flying one yet' is that you are still in high school, haven't started flying training yet and, quite frankly, haven't got a clue what you are talking about.
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Old 19th Jul 2001, 23:57
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Vaqueroaero said it!! That's what I mean by that!
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Old 20th Jul 2001, 01:34
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Smile

Cody, I have some 170 hours on the MD902 explorer, and feel that you have indeed a quieter machine,but, the handling is a little ...... different !!!
Safety with these types is tops - providing you appreciate the flight characteristics of Coanda effect and the Notar system. All helicopters WILL bite given enough reason ( I hear what you say Letsby - I remember the prang only too well) I have run out of pedal in a very high wind - but the 902 is a big slab sided aircraft. You MUST know what is going on at ALL times ( brain ahead of machine ) and be prepared to counter limited power or control situations at the moment they occur.

FLIR
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Old 20th Jul 2001, 05:31
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Copter Cody asked:
Who believes that the new NOTAR systems should be standard on most all single engine systems?

Nick sez:
Not the US Army. The NOTAR equipped OH-6's they tried were so poor they retrofitted them back with tail rotors. The NOTAR is really a very ineffecient tail rotor buried inside the tail cone, with enough lost energy to cost at least one passenger of payload in a 4 passenger aircraft. The noise is quite a bit lower, and it is clearly safer if you stick your tail into obstructions, so you have choices.

Cody said:
All of the statistics show that a machine with the NOTAR system is significantly safer as well as better handling and is much quiter. They say that the helicopter is more flyer-friendly.

Nick sez:
NOTARS are quirky and not particularly user friendly, that's why they need a built in stability system to quell their basically neutral stability. Nothing like swapping ends at 100 knots to make you disagree with Cody.

One great topic we could toss around is the concept of the natural give and take of design, where each attribute gives some benifit and costs some panalty. Beware of any question that front loads the attribute but forgets to mention the price tag. The best way to phrase the question is "Who wants to lose 20% of the payload of their helicopter to have a protected, quieter tail?" Some folks will say Yes, and that's OK, but at least they have answered the whole question.
 
Old 20th Jul 2001, 09:12
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I have about 700 hours in the MD520N. And about the only good thing about, it is safer on the ground (not in the air). It does not work well at altitude. Not stable in winds. Tail takes too much power...etc. Although the tail has the same authority as the MD500E, it reacts to inputs a lot slower. Just before going through transitional lift on landing, you need to pull a slight amount of collective in, and slight forward cyclic to stop the "ass tuck" it likes to do. You should see what the manuel says will happen if you have a tail problem (stuck thruster, pedal) get below 20kts, and you are not skidding on the ground.

Although I do not know what the winds were in Mexico, the MD600N has a critical wind azimuth in the limitation section that says that at high altitude and any weight, you can not have any wind on the right rear area. You can exceed the power limitations attempting to correct for the winds. That is a possibility of what may have happened.

Also, a lot of the police departments in the western U.S. are dumping their MD520's and MD600's they have. A fair amount of them are going back to MD500E's.
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Old 20th Jul 2001, 17:54
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Cody,
Again,where are your statistics? I would love to see them please!
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Old 21st Jul 2001, 13:17
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Thought so......................
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Old 21st Jul 2001, 14:53
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Cool

Is there a limit to the size of a NOTAR helicopter?
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Old 21st Jul 2001, 16:27
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I would imagine that as it is an aerodynamic force that gives the antitorque ( flow of air around the tailboom ) , for a larger aircraft with more torque you would need a combination of larger diameter tailboom , longer tailboom ( 600 seems kinda long already) or greater air flow . I am sure there is a certain weight where the weight penalties would make the notar impractical . I was told eurocopter tried a fenestron on the Puma without much success. Anyone got any opinion as to if a notar would work on a 430 or S76 ?.
Just read Nicks post on the subject , Nick will they try fan in fin on the S76 ?

[ 21 July 2001: Message edited by: widgeon ]
 
Old 21st Jul 2001, 23:26
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To Sling Load,

go to http://www.ntsb.gov/ntsb/Month.asp
See for your self, bye the way, patience is a virtue.

Cody
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Old 22nd Jul 2001, 02:21
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Doesn't answer the question!!!
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Old 22nd Jul 2001, 02:52
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"Copter" Cody,

Children should be seen and not heard.

Wait until you learn enough to be relevant, knowledgeable, and interesting before you post. You should be concentrating on getting out of high school instead of cluttering this and other forums with your chatter.

Did you really think that your post of the url for the NTSB monthly page was a legitimate answer to Sling Load's request for more facts?

Most everybody has given you the benefit of the doubt and tried to answer you questions. As far as I'm concerned you have used up that doubt.
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Old 22nd Jul 2001, 06:18
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Lama Bear said:
I would imagine that as it is an aerodynamic force that gives the antitorque ( flow of air around the tailboom ) , for a larger aircraft with more torque you would need a combination of larger diameter tailboom , longer tailboom ( 600 seems kinda long already) or greater air flow . I am sure there is a certain weight where the weight penalties would make the notar impractical .

Nick sez:
The NOTAR is actually only partly a Coanda flow tailboom anti-torque system, it also needs a tip thruster to help generate anti-torque. It cannot make it with either one alone. The tip thruster is very necessary because in many hover situations, the main rotor downwash does not flow over the tail at all (that is why the limitation on wind from the rear, where the wind blows the main rotor downwash forward, away from the tail.) The NOTAR has two virtues, protection and low noise, but it has a whole list of deficits, including its high power consumption, poor handling qualities, poor stability at high speed, wind speed limitations, mechanical complexity (many more moving critical parts than a tail rotor) and high weight. I'll bet it scales up quite poorly, but I have no data to back up that intuition.

Lama Bear asked:
I was told eurocopter tried a fenestron on the Puma without much success. Anyone got any opinion as to if a notar would work on a 430 or S76 ?.
Just read Nicks post on the subject , Nick will they try fan in fin on the S76 ?

Nick sez:
We looked at NOTAR for Comanche. In our studies, NOTAR had no advantage over the Fantail, and Fantail provided exceptional maneuverability, a real plus for the recon/attack mission.

We used the S-76 as the test bed for the fantail that is on the Comanche, and it worked quite well, but we had no intention of adapting it for the production S-76 family. It weighs a bit more (about 50 pounds) and because it must be mounted on the tail drive shaft axis, it protrudes down below the tail cone by a bunch, and presents more of a ground contact problem. Comanche has a tail wheel, and so has no such issue.

The Eurocopter folks told me that they did try to use a fenestron on a Puma as a development tool, and it dod not scale up well at all, and was abandoned.
 

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