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The NOTAR.

Old 11-05-2014, 03:36 AM
  #1  
thepiper92
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Default The NOTAR.

https://www.youtube.com/watch?v=q9NPDFGeC6I

http://www.mdhelicopters.com/v2/notar.php

I'm intrigued by this NOTAR, and I think it would be interesting to use on RC heli, assuming it would be a scale heli, not a stunt heli. After looking at the MD helicopter site and vid, I am filled with confusion. What I understand is that the slits in the right side of the fuse allow for the Coanda effect, allow flow from the rotors to 'stick' to the boom longer on the right side than the left side, as well as increasing airflow/ decreasing pressure. This creates an airfoil like a wing, in which the faster moving air losses pressure and the higher pressure air on the opposite side pushes against the the airfoil, allowing lift (This is the Bernoulli effect, but this is not the only aspect to lift in an airfoil though). I am guessing the NOTAR relies more on this than a plane's wings. What doesn't make sense is that the rotors rotate CCW, and would cause the heli to yaw CCW without counter torque. Looking at the NOTAR, wouldn't the lower pressure air on the left side of the boom actually "push" the boom and join the torque from the rotors, rather than go against it?

Hopefully someone can explain this.
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Old 11-06-2014, 01:11 AM
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pizzano
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The concept and design has been around since the 1940's.....at least three different companies have tried since the 1960's to get it accepted into main stream use. The U.S military played with it in the desert. Sand, dust (maintenance), lack of decent cargo (load) capacity and fuel economy became major obstacles......

MD is the latest manufacture, once again, marketing it to local law enforcement, media services and Euro based outfits....even China has looked at it......

In the late 70's up to the early 1990's, a few local California coastal communities law enforcements had a few in service......not any longer. At over $1,000,000.00 a pop and a maintenance budget to match, it was not a cost effective product.

As a scale hobby model......the technology is impractical due to serveral complicated issues.......the power source(s) required to operate both a small turbine and maingear head assembly, would out "weight" it's efficiency. Run times and agility would be poor, even if it were designed as a 600 or larger.......let alone the enormous number of service hours being spent keeping it tuned and cleaned.....it would have to be electric, as a gasser it would be a nightmare to maintain.

I know of no retail hobby manufacter who has succesfully built and sold a Notar designed craft (to date).............except maybe a coaxial, which is essentially a no tail rotor heli craft........

Edit:

I stand corrected.....Vario makes one:

http://www.vario-helicopter.net/prod...mechanics.html

And its a gasser........
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Old 11-06-2014, 05:57 AM
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Wonder if it would be possible to have an df setup to just hold the tail and use the end area for control, rather than a variable pitch. The end area would compensate through gyros. Perhaps standard setup with a torque tube elimating at an df, of which carries air like the NOTAR through the boom. this wouldnt have the crackwhip tail authority of standard rc helis, but basic flight would work (I gather such a setup can't do inverted well). I read about the Vario but couldn't find a link.

What I don't understand is the physics. If the rotor turns ccw, it would cause the whole heli to yaw left without anti torque. Say you put the heli on its left side, orienting the boom like a wing. The "top" redirects the air, speeding it up and allowing air to conform to the boom longer. This becomes the top of the wing. The "bottom" is like the bottom of the wing, slower and high pressure air, thus creating lift. Now orient the heli normally...isn't this left applied on the left side of boom, thus "pushing" the boom ccw?
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