Splitting the needles

[CHPL]

Hey,

I'm a formal commercial helicopter pilot, but not flown since more than 10 years.:cry:

I'm using DCS and especially the UH-1 Model for training and practice maneuvers.:pilotfly:

I've been totally impressed by the graphics and flight model in DCS and of course The UH-1 Model. Great job.:thumbup:

But there are two points I have to mention. :helpsmilie:

1. Splitting the needles, in preflight or while practicing autorotation does not work. Even with throttle in Idle position during autorotation, Rotor RPM and Engine RPM needles stay together. The Governor is not the problem. The indication remains the same even with the Governor in emergency position (off)

2. Using seamy professional flight controls like Komodo (http://www.komodosimulations.co.uk/Controls.html) or OE-XAM http://oe-xam-simulators.blogspot.de/, the gap between fully closed and Idle position would not be recognized. I have to use the keyboard to bring the Throttle into idle position. Only after that my Cyclic throttle reacts. Closing the throttle below Idle to shut down the engine, also only works with the Keyboard.

I hope there will be an easy solution, and these problems are fixed not so far in the future.

But I will have a lot of fun anyway. :joystick:

[Cibit]

Not sure I follow, If N1 reduces then surely N2 must follow or maybe I don't understand :helpsmilie:

[Flamin_Squirrel]

Not sure I follow, If N1 reduces then surely N2 must follow or maybe I don't understand :helpsmilie:

 

In a helicopter there's a one way clutch; the engine can drive the rotors, but the rotors can't drive the engine (or more importantly, so a dead engine won't slow the rotor). Therefore the engine can spin slower than the rotor, but rotor can never rotate at lesser speed than the engine.

 

If you cut the engine, it'll should slow faster than the rotor (assuming collective is lowered e.g. during autorotation) and you'll see a split in the needles (on the instrument that shows engine and rotor rpm), which is what the OP is describing.

 

However, this is no longer happening in the DCS Huey. It used to, so well spotted CHPL, you've found a new bug! I promise it used to work properly and I'm sure it will again when fixed.

 

edit:// slight clarification: the turbine isn't directly geared to the engine, so the rotor can spin slower, but I think only at a lower engine RPM. I'm not sure, I've not flown a turbine helo before.

Edited March 4, 2016 by Flamin_Squirrel

[Flamin_Squirrel]

I hope there will be an easy solution, and these problems are fixed not so far in the future.

But I will have a lot of fun anyway. :joystick:

 

Hope you don't mind, I've raised your point in the bug forum:

 

http://forums.eagle.ru/showthread.php?p=2701365

[CHPL]

Turbine Engine

 

Thanks’ Flamin-Squirrel for forwarding my request. :thumbup:

Your totally right about forces driving a Helicopter, except, in a turbine isn’t any clutch. :music_whistling:

Broken down to the very basics, a turbine engine is a combination of two Parts.

Part one - Compressor (N1) and burning chamber, creating a very hot and fast airflow.

Part two - is comparable to a “windmill”, located in that hot, fast airflow, and driven by them. Tis “windmill” (N2?) drives the Rotor over the transmission, whichever reduces RPM to Rotor RPM.

However there is no mechanical link between the throttle and the Rotor system like for example piston - piston rod - drive shaft – clutch – transmission – Rotor.

In an Piston engine, you have somewhat I think its named “power/swept volume ratio “ ( moving mass off Engine Parts) which causes des System to react very quickly even by sudden power changes.

In a turbine engine, the “windmill” reacts very slow, because a lot of hot air (which is the only driving force) passes over it bevor it stars to Speed up. :cry:

Rather in a turbine helicopter, if the Rotor system demands, due to Pilot inputs :pilotfly:(for instance to late, to fast, and or, to much collective) more power, Rotor RPM will drop :harhar:even the engine (N1) speeds up. (surprise, surprise)

Many PC pilots confuse that issue with “settling with power” or Vortex Ring State.

The result may be the same – too much gravity and to less Air remaining!

 

The whole System reacts much slower, and the Pilot has to cep that in mind. :doh:

[Flamin_Squirrel]

Your totally right about forces driving a Helicopter, except, in a turbine isn’t any clutch. :music_whistling:

 

Yes, I know that the rotor isn't directly connected to the engine.

 

That said, the DCS Huey manual describes a 'freewheeling unit'. That sounds like a clutch of sorts to me, so I guess some turbine helos have one, some don't?

[kilix]

I wonder if there is any clutch in modern helicopter engines/transmission.

When the generator turbine is on a different shaft than the power turbine, is there any need for a clutch?

[Sid6dot7]

That freewheeling unit disconnects the main rotor transmission and the free turbine shaft from each other in any case where the rotor rpm are much higher than the FT ones. It protects the main rotor hub transmission from damage and helps to keep the main rotor sustain it's rpm with minimum resistance. If the core engine doesn't drive the free turbine wheel (i.e. engine failure) it acts like a rotor brake and will unnecessarily reduce the main rotor rpm, nothing you want when autorotating.

 

Every turbine driven helo has such an unit, especially multi-engine ones. Exceptions possible but unknown. :P

 

And yes, the freewheeling unit is basically a centrifugal clutch with a typical aerospace design (much simpler and more fail safe). Search for Sprag Clutches.

Edited March 5, 2016 by Sid6dot7
typos, language .. all the good stuff

[CHPL]

Yes and No

 

First of all, you all mad a great Job !! :thumbup:

When started with DCS I watched a lot of YouTube Tutorials to get familiar again, with Radios, Navigation and Mission Editor. I’m glad to have such Information channels and somebody assisting my, by any aspect in DCS.

I don’t want to be a “Klugscheiser” (someone how news everything better) :pain: but in fact I’m degraded from real life flying to PC simulation.

Pitiful- I now. :cry:

But I’m still alive because of this knowledge. :smartass:

Any Helicopter has a freewheeling unit, located at the Main Rotor drive shaft, that allows the Main rotor to turn free, disconnected from any other moving Parts creating more or less friction. Almost any bicycle has one, allowing the driven wheel, to turn even you did not pedal.

It sounds like a clutch, but the purpose is different. Especially multi-engine helicopter have a tendency to screw up' transmission, so they have a superior accident rate then single engines have.

But even when the transmission is blocked, the Main Rotor is still turning, because of the freewheeling unit. :pilotfly:

[Sid6dot7]

Any Helicopter has a freewheeling unit, located at the Main Rotor drive shaft, that allows the Main rotor to turn free, disconnected from any other moving Parts creating more or less friction.

 

Not any (referring to the disconnection of moving parts). The main rotor is still connected to the main gearbox/transmission as it drives the tail rotor and oil/hydraulic pumps in case of an engine failure. Freewheeling units are found between the engine(s) and the transmission system, as well as transmission and tail rotor. Everything else is a design choice and not mandatory.

Edited March 5, 2016 by Sid6dot7

[CHPL]

You are absolutely right !! :thumbup: