You are talking about NOTAR popularity. I believe, in this case, one needs to look at the environment within which NOTAR is produced - a firm which has battled with some fairly fundamental challenges for the better part of the past 20 years and which struggles to attain steady growth in terms of sales.

Had this not been the case, and say the NOTAR patent sold to a manufacturer with a significantly higher product throughput, one might have witnessed the progressive refinement of the technology resulting in improvements in its operational effectiveness and further boosting its popularity.

Because early publicity surrounding NOTAR technology intimated that exhaust gases would be integrated with accelerated ambient air to pressure the boom. When this option was not selected the corresponding publicity was considerably less (.. one can understand how a front page heading in the Herald Tribune "Hughes Backs Down From Integrating Exhaust Gases in Newfangled Helicopter Technology" might have limited readership appeal) .. and, consequently, those lacking proximity to NOTAR development and operations did not appreciate that this strategy had been altered.

PPRuNe's Rotorheads and other mediums are doing a great job of educating (well, most of the time ;)) those who are interested in these things.

S.

The mythology of Notar has grown, and continues to grow, due to the excellent public relations campaign that was conducted 25 years ago. Here is some factual info:
1) Notar works, is effective, flies well and is quieter and generally immune to tail strikes. People who fly them like them.
2) Notar has considerably more critical parts than a tail rotor. It has a tail rotor inside its tail cone, with all the tail rotor stuff, and it has a Coanda slot, and it has the rotating nozzle at the tail, and it has the sas and sometimes a rudder. It costs more, weighs more, has mor maintenance and more critical failure potential.
3) The Coanda slot has limited use as anti-torque. Only in very low wind does the main rotor wash fall squarely on the tail cone, allowing the Coanda magic to work. Every other time the Coanda effect is small, and Notar uses its tail tip thruster, which is fairly inefficient.
4) The power losses of the Notar are fairly large, relative to an open tail rotor, so the payload of a Notar is lower, or the installed power is higher.
5) Why fewer Notars? Less payload, more fuel flow in cruise,(but also quieter, less likely to have a tail strike.)

The customers choose.

If you do a lot of landings, particularly ad hoc urban and rural, a notar feels good, from a safety perspective.

We've just logged 100hr and 600 landings in our new 902.

NOTAR
 

I must rely on the experience of others who have actually flown them but I'm told that the weight of the fan mechanism takes some getting used to. It's situated immediately behind the cabin and not easily balanced.

For military uses it might prove advantageous to be able to back into a dark notch in the woods and either land or observe from the hover. However, it will take some practice to perfect. I've also been told that the reaction time is notably reduced.

sgt major
i have not heard that one yet but its not true anyway

sgt major
i have not heard that one yet but its not true anyway

Yep sadly, I think when NOTAR came out a lot of the heli industry looked and went ooooo thats a big contender, and then slagged it hugely. Then it came out, in small dribs and drabs, and true it was not well supported in parts support then ( ten yrs ago now). Nor was the B747 went that went out and commercial companies said its too big!!!
Times move on and it has still found its place ( among all the slagging) as always it is customers choice. I am not a pilot to slag EC/Bell/Augusta/ or who ever. They all have their merits and bad points! However in my limited time doing the occasional HEMS work in UK I find them...... bloody brilliant for that work. I have not flown an EC135 so can't say, mates of mine have and they like erm , so there you go. As to the question as why has NOTAR not taken off, I think who has the licence for it!!! always wondered why there was not smaller versions of a Chinny about, there is I know a HELIX but who has the licence!!!:ok:

BT.

You have a "NEW" 902?....

1st time I'd ever flown a helicopter with just 15 hours on the clock.

That's new for me.