I still believe this is very improbable.

Other ABH types also vary Nr automatically to reduce the noise signature, but they do it as a function of altitude. One type I am familiar with varies from 342rpm at SL to 350rpm at 5000 ft and above.

Edit: a bit of research finds this ICAO research paper on Helicopter Noise: http://www.icao.int/environmental-pr...April_2015.pdf

(for the H130)

212man - that's a good find and confirms the idea that reducing the Nr on the 130 is about reducing both MR and TR noise - everyday's a schoolday:ok:

The 365 N3 also has Nr rescheduling from 355 at SL to 360 at 5000' but that, and the 365 switch (guess what Nr that gives) is to help reduce Nr decay in the event of a SEF at a critical stage of flight rather than noise reduction (which you wouldn't get by increasing Nr according to that linked paper).

The AS350B3e increases NR based on pedal position. It does it for all altitudes.


The Eurocopter THM for this aircraft indicates that the increase is for "good performance in case of engine failure, and increase of maneuverability in high winds." (B3e THM, Rev 05-2011, pp. 13.13).


The increase in NR occurs abruptly, so abruptly in fact that operators have over torqued engines as a result of large pedal inputs when hovering near max torque.

SFT thanks
Quoting myself : "The H130 has Pedal Position sensors (or transducers) and alters it's Nr because of the inputs recieved therefrom. The offical reason is some nonsense about being quieter (and it is very quiet), but the real reason is likely to be to produce more TR thrust in the hover. " (The H130 is in fact an AS350B4)

JE: normally a considered poster, I am hurt that you read it that way. Have you actually followed Crabs doubt that this occurs, then his confusion about it being a YAW sensor rather than a PEDAL POSITION sensor (also a transducer, not relevant), his insistance that I had got it wrong about being a transducer, when infact this sensor is (almost always) a transducer (most are, and this one is), and now he's still trying to say it's about noise (which is the marketing line) but it is obviously more to do with needing more Yaw authority in the hover. You feel free to back that horse, but I don't see the more technically correct part. And what are you saying about knowing my experience, you should not be able to, this is an anonymous forum, but if you did, which I doubt, then you would know that I have about twice the flying time (to name but one fairly unimportant yard stick) of crab, so I think it is fair to make the 'relative' qualification, in conjunction with how wrong he has been just on this thread alone. and megan, (rather questionable family car), "prat", well thanks!

I different Nr gives an additional problem in a helicopter with tuned anti vibration devices of not being in tune at both frequencies (a problem addressed in the H130T2), maybe crab will expand for JE? :rolleyes:

AnFI,

Again you carry out what seems to be a blinkered approach, choosing to defend your position rather than consider the possibility that there could be merit in the criticism of you. That, in my experience of following your posts, does you no favours and detracts from the discussion which is not about a single engine helicopter (I first endorsed on the 130 some 8 years ago, thank you) but most likely about the Indian Dhruv.

And to compare yourself to crab@ on the matter of hours flown holds little or no water on this forum, even if your assessment is accurate. It would improve Rotorheads immensely were you to discuss thread topics with less emphasis on your beliefs and more on the actual topic.

Yet again AnFI - your pomposity and self-aggrandisement are breathtaking - everyone else is wrong and only you are right:ugh:

You know better than Airbus about why the 130 has Nr reduction in forward flight - have you written to tell them?

So you have 18,000 plus hours then?? Clearly you didn't learn anything in any of them and your lack of humility must have made you a joy to fly with.

Troll......

An 18,000 Hr+ helicopter pilot, is there is such a person anymore? AnFi, if so; you must be as deaf as a post, your eyeballs must permanently rattle around in their sockets and your 2 remaining teeth require a daily visit to the dentist, your back must be fused solid and skin permeate inescapably of Avtur.

Apologies in advance to any helicopter pilots out there with the requisite 18K+ Hours!!!!

Well said JE. Thats both of you.

JE "...consider the possibility that there could be merit in the criticism of you" I do, and there must be some truth to that, that despite actually being right and facing constant insult, it is I that somehow create that feeling.
"less emphasis on your beliefs and more on the actual topic. " well my beliefs seem underrepresented here, is it really that unreasonable to air that philosophy? I am not surprised that the SE arguement riles people, since so much effort and expense has been devoted to a technically questionable philosophy, with such atrocious results. (just look at the death rates in GOM vs NS)

As for the experience etc etc I have continuously tried to stay away from mentioning any specifics, despite constant badgering, I give one hint and am met with a barrage of sarcasm and insult. Not very civil crab, mostafa, megan (prat?)

I asked Crab what he thought about the Dhruv, no answer. What do you think about it ?
Seems unsuccessful, probably a waste of time trying to use a twin, when performance and simplicity of an SE in that scenario would probably have a better yeild, don't you think?

JE knowing the 130 also you would know all along that what I have been saying is true then, please confirm. (wrt transducers and Yaw vs Pedal Position)
Why do you think they vary the NR according to PEDAL POSITION?
Do you disagree with my reasoning wrt marketing against material performance of the T/R, I suspect that you don't disagree.

Note just more insult from crab, I am surprised that respected JE would align himself with that approach.

Never flown it - have you???

what exactly is it you have to hide AnFi? No-one else has any problem with being honest about their experience and background except you - and then you wonder why you are treated as a Walter Mitty character and regularly derided!

If your arguments are to carry any weight at all you should come clean - unless, of course, you do have something to hide:E

no have not flown the Dhruv, have you?
It doesn't look very successful, and if it is the object of this thread then I'd say it is even less successful than it's (poor) record indicates. What do YOU think?

as I allways have said I don't think experience is key, I think the merit of the arguement should stand in it's own right, I am open to learning from lesser experienced people, i would not wish my greater or lesser experience to get in the way of a reasoned position, I would not wish my views to carry weight by virtue of experience, but I am happy for you to believe that yours do. I have said it often and I hope you can understand and respect my view on that. Simple really.

Nobody cares! Get it over with. Get back to topic, please.

Wow. Came here hoping for an answer to the same doubt, ended up reading a silly back and forth.

I fly an ALH (Dhruv) as well. The torque rise phenomena is absolutely confounding because common sense tells me translational lift should reduce torque requirement. But torque of both engines rises significantly on its own while crossing transition and a small bit later around 50-60 kts. I've heard a similar (attempted) explanation about control rod movement but it doesn't sound remotely convincing. I have a strong feeling its an aerodynamic phenomena, but I'm at a loss for ideas.

PS:- it really isn't as bad an aircraft as it's made out to be.

You can get something "similar" on the H145 where the yellow Take Off range is only usable up to roughly Vx speed. As the Helionix is very integrated the yellow range disappears at or about Vx speed and you will incur an "event" if still within the yellow.

Use of the yellow range is limited to speeds in most helicopters due to varying factors.

Only some helicopters are smart enough to catch you out! Happens quite regularly until folk are aware of it.