Still learning, but this confuses me.

[Sm0k3y]

Hi guys/gals

 

2 weird things happened in this flight

 

1: I ubruptly tried to bring helo to a hover which ruined an engine, which is understandable considering how I attempted the manuever. however left panel warning lights said something wrong with Left Engine and the Top panel said something wrong with Right Engine (or vice versa, cant remember now)

 

2: Trying to use Vikhrs. Spotted target with HMS, locked target, fired. Vikhr went off on its own mission... Not entirely sure where it went but it didnt hit the target. (I did have to switch to manual as I may have been too close??, would this cause the Vikhr to completely miss target?). Sometimes you get a range of target using Shvkval sometimes you dont. Could be doing something wrong I guess.

 

I would like to know why the Left warning lights said something wrong with Left Engine and the top panel said something wrong with right.

 

And would like to know why Vikhrs didnt fly designated path.

 

And yes the crash at the end was from my own stupidity (Never drink and fly)

 

P.S First post, Hello All! What an amazing sim!

 

P.P.S Still learning this sim, only 3-4 hrs stick time. And 9-10 Hrs reading/watching utube

 

P.P.P.S I never reviewed the track as its 12:27 am and need sleep so could probably answer these questions once Ive had some sleep. And please watch track before replying. Its not that I dont appreciate feedback, its just I would like you to see whats happening first.

Numerous Disasters.trk

[159th_Viper]

......I would like to know why the Left warning lights said something wrong with Left Engine and the top panel said something wrong with right.....

 

 

WARNING - Caution Lights panel (Left/Red):

 

Warning Light was LH ENG VIBR. Also evident on the EKRAN. Indicative that the Limitations for the Left Engine Vibration has been exceeded, thus rendering the Left Engine in Dire need of Repair.

 

Now, completely unrelated to the above-

 

MESSAGE - Right Overhead Panel (Yellow):

 

Message Light was RH POWER SET LIM. Indicative that there was a Potential for a PT(Power Turbine) Overspeed, which if left unchecked would have led to an Engine Shut-Down to prevent said Overspeed. In order to prevent this, the Engine was limited by the Electronic Engine Governer, thus stopping your Good Day from turning Nasty :D

 

 

 

......And would like to know why Vikhrs didnt fly designated path.....

 

You neglected to Arm the Laser. Also a good idea to toggle the Moving Ground Target Mode on, even though the target is stationary.

 

 

Welcome to the Forums :)

[AlphaOneSix]

To add/amend the above:

 

For the second question, yes, you never turned on your laser.

 

For the first...

 

You turned on your right engine governor, but you never turned on your left engine governor. When you did your crazy "hover now" move, you tried to pull in way too much power. Since your left engine governor was not on, you overtemped that engine and damaged it (although it seemed to continue working). Your right engine had the governor enabled, so the governor limited the power applied to that engine to prevent you from damaging it. When the governor did this, it turned on the "power set limit" light. When that light is on, it means that the governor is stepping in to reduce the fuel flow to the engine to prevent damage from overtemp.

 

Note: The governors don't do anything to prevent a PT overspeed, they only step in to reduce fuel flow to prevent an EGT overtemp. The governors just shut the engine down if there is a PT overspeed.

[AlphaOneSix]

Something to add:

 

Max EGT for the engines is 990 degrees C. EGT limiting by the governor will step in before that to start reducing fuel flow, but will eventually let you get all the way to 990. Without the governor on for the left engine, it just shot past 990. At 1050 is when you got the vibration warning, and at 1075 the engine became damaged. At that point, the left engine RPM dropped to 89% and would no longer get any higher. Your right engine started to do most of the work at that point, since the left engine was in a degraded state.

[nemises]

I love this sim

[sobek]

This reads like the technical report of the chernobyl incident.

[AlphaOneSix]

This reads like the technical report of the chernobyl incident.

 

DCS: Nuclear Power Plant?

 

Sid Meier's Nuclear Power Plant Tycoon?

[sinelnic]

S.T.A.L.K.E.R. the prequel?

[My Fing ID]

I was reading on on Chernobyl again a few days back. Freaky stuff. Glad they don't make those kinds of reactors anymore

[sobek]

I was reading on on Chernobyl again a few days back. Freaky stuff. Glad they don't make those kinds of reactors anymore

 

Not the reactor was the problem, it had enough safety features to prevent or deescalate the situation. Dumb people, however, are being manufactured as we speak. :doh:

 

Edit: To be fair, the Chernobyl staff was probably not dumber than any other NPP staff, just badly educated.

 

Edit2: Sorry, my tendency to go OT again :music_whistling:

Edited November 5, 2009 by sobek

[Sm0k3y]

Ahhhh :doh:

 

Thanks alot for the detailed answers. I can't believe the learning curve of this game, insanity.

 

Now to try improve my rocket aim, havnt been able to hit anything without being right on top of the damn target..

[Frederf]

The trick to rocket aiming is to be very steady for 1-2 seconds before release. If you try to tap it fast just as the cursor slides over the target while flinging the airframe around then accuracy will be poor. Also having the right ballistic setting and laser ranging helps too. At the end of the day rockets are not precision weapons so adjusting expectations helps.

 

Alpha1Six, here's a question that's been bothering me for ages... is it bad to run with the LH/RH Limit lights lit? If the governor is limiting power effectively can I ignore it and just worry about the K H B linear gauge on the wall or should I keep fiddling with the power to be just short of the limiter?

[AlphaOneSix]

I'm not sure exactly how the game handles it. In real life, we just don't get into those situations, but then again, we don't have to. The topic at work did come up recently however, and we came to the conclusion that if the governor is limiting your EGT, then there is no problem (I would still think it's a bad idea to stay in the situation for long, however). Of course, since the governor is restricting your fuel flow, pulling more power will result in reduced rotor speed

[sobek]

I'm not sure exactly how the game handles it. In real life, we just don't get into those situations, but then again, we don't have to. The topic at work did come up recently however, and we came to the conclusion that if the governor is limiting your EGT, then there is no problem (I would still think it's a bad idea to stay in the situation for long, however). Of course, since the governor is restricting your fuel flow, pulling more power will result in reduced rotor speed

 

But there are time sinks for the different power levels, right? Max cont. is way below where the governor has it's absolute limit.

[AlphaOneSix]

Well, the EPR gauge indication (where the middle needles sit) is based on the outside air temperature and pressure, but the EGT limiting is based solely on the EGT of the engine. I have run into situations in the game where the EPR gauge showed I was in cruise power, but I was still getting EGT limiting.

[RvETito]

In case the EEG is inop you may continue normal operation but you have to pay extreme attention at high power settings to avoid GG RPM and EGT overlimit. In general that means to look at the GG RPM and EGT gauges and when Ngg reaches take-off power (depends on the ambient temperature but in all cases is not more than 101.15%) and/or EGT 980-990'C - DO NOT increase the power of this engine (read do not pull on the collective more unless you move it's throttle lever from AUTO to Idle). This is how it works in BS, this how it works IRL ;)

Edited November 6, 2009 by =RvE=Tito

[Frederf]

I commonly get into situations in DCS where I'm getting the limit lights starting up when I'm well below even the cruise power indication, especially at high altitude. A lot of time my power indicator is floored and there's no way I can get to Max Cont or even Economy Cruise power without setting off the LIM lights! I'm sure there are situations where either the EGG or the Max Cont kick in first but most of the time the LIM lights are the limiting factor by far over the power meter limits.

 

My usual MO is to tickle the collective just below where the LIM lights illuminate but if I could just "set it and forget it" and not worry about the limiter lights then I could reduce my cockpit workload.

 

Like you said, if I run with the LIM lights on I would get to 990°C EGT which is a bit higher than if I would make myself keep the LIM lights off. But running at 990 EGT should be safe for the duration of the flight, just probably not make your chief mechanic too happy.

 

Of course there is the safety consideration that if the EGG fails and I have a high collective setting it will require prompt action to avoid engine damage or failure but I'm purposefully ignoring that consideration for the moment. Right now I'm assuming all systems 100% operational.

 

Now I forget what the 2 Idle notches on the throttle are. There's some normal idle and the one above it is something like EGG-inop setting?

[RvETito]

Now I forget what the 2 Idle notches on the throttle are. There's some normal idle and the one above it is something like EGG-inop setting?

 

No, that's for free turbine (rotor) RPM governor failure.

[AlphaOneSix]

But running at 990 EGT should be safe for the duration of the flight, just probably not make your chief mechanic too happy.

 

Regardless of what the EPR gauge says, 990 puts you in the "takeoff" power range, which you should not stay in for more than 6 minutes. The max EGT for unlimited duration is 870. The "max continuous" or "nominal range" (despite its name, you can't stay in it continuously) has a limit of 60 minutes at an EGT of...I forget off the top of my hed and I don't have quick access to my manuals...I think it's 920.

[Frederf]

No, that's for free turbine (rotor) RPM governor failure.

 

Ah, close to what I was thinking. So there are two types of governors EEG and FT? If the FT governor fails then the collective low/nominal fails too right?

 

Regardless of what the EPR gauge says, 990 puts you in the "takeoff" power range, which you should not stay in for more than 6 minutes. The max EGT for unlimited duration is 870. The "max continuous" or "nominal range" (despite its name, you can't stay in it continuously) has a limit of 60 minutes at an EGT of...I forget off the top of my hed and I don't have quick access to my manuals...I think it's 920.

 

The EPR gauge is just a fancy EGT gauge then?

 

Let me state something and you tell me if it's correct. If you run the engines such that the LH/RH LIM overhead warning lights come on that means you have reached an EEG limiter somewhere below 990 EGT but over some time the limiter will allow you to approach the 990 EGT limit, which corresponds to the take off limit. That would suggest running with the LIM lights on is not a good thing at all.

 

What confuses me is that the limiter lights are coming on well short of the EPR takeoff mark. Even if I ran it forever I don't think it would get up to the takeoff mark on the EPR gauge. Is the EPR gauge lying to me? Am I reaching 990 EGT but not showing T/O on the EPR gauge?

[AlphaOneSix]

Ah, close to what I was thinking. So there are two types of governors EEG and FT? If the FT governor fails then the collective low/nominal fails too right??

 

The EEG is actually three governors in one.

 

First, it provides EGT limiting to prevent overheating the engines.

 

Second, it provides GG (N1) overspeed protection by shutting down the engine in the event of a GG overspeed of around 107%.

 

Third, it provides FT (N2, PT) overspeed protection by shutting down the engine in the event of an FT overspeed of around 116%.

 

 

 

The EPR gauge is just a fancy EGT gauge then?

 

The EGT, as I'm sure you already know is a direct temperature reading, based on input from a bunch of thermocouples on the engine. The EPR gauge (engine pressure ratio) gets no info at all from the engine temperature. The center needles (cruise, nominal, takeoff) are positioned based on the current outside are temp and pressure. The outer needles are position based on an air pressure reading taken from the engine itself. The numbers on the gauge correspond to the engine air pressure in kg/cm2.

 

Both EGT and EPR are indications of your engines power output, they just use different methods to figure it out.

[RvETito]

A couple of things to clarify:

 

- The engine is controled by four governors in total:

 

1. Ngg centrifugial mechanical governor - maintains the set gas-generator RPM

2. Nft centrifugial mechanical governor - maintains the nominal free-turbine (main rotor) RPM

3. EEG - electronic engine governor which has two functions - limiting the maximum Ngg as a function of the ambient static pressure and temperature and free-turbine overspeed protection by shuting down the engine in case of FT overspeed (which could happen in free-wheel clutch failure for example)

4. EGT electronic governor which limits the EGT up to 990'C regardless of ambient conditions. It sends signal to the command solenoid on the main engine control unit through the EEG, that's why sometimes the EGT limiting is "assigned" to the EEG but the EGT governor is actualy a completely independant device.

 

The EEG sends command signal to the solenoid limiter (which activates up the amber lights on the overhead panel) either calculated by it's own Ngg threshold or by EGT governor threshold using "OR" logic i.e. whichever occurs first. The perfect engine adjustment would be when the two thresholds match - that means that you squeeze the maximum out of your engine.

 

About the engine power indicator - it indicates compressor pressure ratio, not engine pressure ratio (according to Pratt&Whittney's term for EPR, being the only engine manufacturer that I know using it) and it's just a backup instrument of judging engine's power. The primary parameters are the Ngg, EGT and Nr.

 

Also the power limiter operates in pulses - you can see the amber light flashing with increasing frequency if you smoothly increase engine power, the greater the frequency the bigger the fuel flow limitation. When they are steady lit up that means full (maximum) fuel flow limitation.

[Frederf]

Just for clarification is it OK to think of the engine as having two halves, the free turbine as the "wheels on the car" (aka main rotor) side and the power turbine as the "crankshaft" side?

 

I'm trying to recall and/or figure out how the engines work. From hazy memory it is something like a gas generator which spins at a high RPM that is not mechanically connected to the gearbox/rotor (FT) but uses air pressure to transfer power like some pneumatic torque converter (automobile analogy). I could be way off though.

 

Ok the EGT is a a temperature gauge and the EPR is measuring the relative temp+pressures of the engine and ambient (possibly in some fancy non-linear way). That explains how I can get the exhaust too hot and get it limited by the EEG well before the EPR is showing a temp+pressures relationship suggesting a high power setting.

[RvETito]

That's a common design of all turboshaft engines - gas generator composed of compressor (axial, radial or mixed), combustion chamber and turbine driving the compressor and turbine machanically connected to a gearbox. That's why it's often called "free" (or "power") turbine because it has only gas dynamic "connection" to the other main components of the engine. The free turbine is the one that represents engine's power capabilites - the engine power rating is given as the output power at the FT shaft. And for it to provide that power it needs the gas generator to create the necessary gas flow to drive it.

[Frederf]

A bit of Wiki learning reinforces the idea. The compressor and the compressor turbine (a.k.a. the gas generator, since its purpose is to generate the gas for the power turbine to use) are mechanically linked, the compressor turbine being after the combustion chamber and drives the compressor which sucks in air. The only purpose of the compressor and its turbine is to continue the engine's operation.

 

The free or power turbine is where the real action's at and is the windmill stuck into the engine's stream of hot air which is mechanically linked and drives the gearbox and so on.

 

All these governors, Ngg, Nft, EGG, EGT limiter only vary on what data they care about to imitate shutdown or throttling. They all enact their control by starving fuel to the engine, yes/no?