Engine Longevity Problem

[Whuping]

As the title suggests I have been struggling in taking the Harrier out for at least two whole sorties. Be damned if I can get it up and land it for the third time. I'm probably pushing the aircraft to its limits, but then again I also find it irregular that it is acting like this.

 

For example. I load up in the Harrier - I bring the aircraft in the air - standard take-off temp at around 720-711. Everything normal. Fan RPM 100%-108%. Nozzles at 30-35 degrees. After about maybe 20-30 minutes in the air, I return back to base to rearm/refuel.

 

This is where the problem occurs.

 

Taking off for the second time same loadout/fuel (ignoring the fuel bug). Engine Temp is now reaching a whooping 780 degrees. At times over 810 degrees even with WATER switch on H2O. Fan RPM 95-90%. Max Thrust Nozzles at 25-20 Degrees now to compensate the sudden loss of thrust and prevent engine to overheat. (Even the green light won't come on to let me know its cooling the engine). In addition, landing in VTOL would result in insufficient thrust regardless of empty weight and also result in me falling out of the sky into the grass/water. (No stores and roughly 2000 pounds of fuel).

 

I have attempted to alleviate the problem by turning off my aircraft and or repairing my aircraft after every sortie, but the outcome is always the same. The second sortie is usually my last one, if I come back alive that is lmao.

 

I'm assuming it is LARGELY user error and I'm just stupid and missing something. It is also worthy to note that I have also tested it out for a long duration flight with two tanks 11k total fuel and nothing else on stores. And the results were the same. Insufficient thrust for transitioning into a sustainable Hover after spending at least 40 mins+ on a flight for a first time landing. Like the engine itself degrades in flight, very slowly.

 

I've tried looking up problems that plagued the Harrier, like Engine Temperature problems or deflating thrust issues before posting. I haven't found any so I'm still unsure if this is a bug or has been mentioned before or is Known. ...Maybe its a feature...

 

Before anyone asks about water levels and damage from enemy fire. Water capacity is usually the same. 400-500. And no damage sustained on many of my sorties.

[DefaultFace]

I've been noticing something similar. Especially after flying a sortie where you took off with water the engine seems to slowly lose thrust. I just did one where I took off and had a max JPT on takeoff of 765 only shortly and with water) and when I came back I put the water switch in landing just in case I'd need it. Surprisingly enough I needed almost full power and Water injection to land at ~18-20000 lbs gross weight.

 

Funnily enough I have a hard time killing the engine if I don't use the water though. Obviously you have to be a bit lighter for this but I find it sticks to the engine limitations better if you do this. With it on sometimes the JPT will just climb to 900 all of a sudden.

 

Also with water injection the RPM and JPT indicators disappear above 105% RPM and the power margins are not shown????

[Whuping]

So far, it seems like the longer you're flying. The higher chance you'll struggle with landing lmao. The engine begins to die at a slow rate once it starts up it seems like. That's the main issue is what I'm getting at. Not sure if this is how it is.

 

I mean, I'm fine if it is how it is in the real bird but even repairing won't "fix" the engine back to its normal state. The state where Temps are at a standard 700-765 range and never higher (as long as nozzles remain 0-15 degrees that is).

[Sphereo]

Are you guys running with DECS on?

[Raven (Elysian Angel)]

I have had this issue as well, and yes: DECS set to ON.

[al531246]

Me and my group are experiencing exactly the same thing.

 

To test it out we did circuits running the tanks dry. We've had an unarmed Harrier down to 100lb's of fuel dropping into the sea. There's no way that's correct. On first takeoff the engine is fine and 9 times out of 10 the first landing is fine. But once you come to the 2nd (or 3rd if you live that long) the engine becomes ineffective and VTOL is no longer possible.

 

I can say for certain that something is not right with the engine performance.

[Texac]

I noticed a smiliar behavior as well.

 

I jumped into the third, Caucasus - Airfield Takeoff and Navigation Quickstart mission. Took off, followed the first few waypoints with little thrust and then pushed the throttle all the way forward after I flew over Sukhumi - Babushara till Beslan.

 

Upon landing approach at Beslan I noticed the aircraft/engine was performing differently depending on the nozzle degree. I crashed, fell out of the sky, right after that when attempting a SL.

 

Perhaps we are really missing something here due to lack of knowledge with the Harrier.

[3mta3]

I'm seeing the same thing. Like the engine power rapidly degrades.

[Vladinsky]

Is this happening without exceeding any limitations?

 

 

[Coxy_99]

Yea i noticed this to, Although today i landed and took off 6 7 times with no issues, I found it more, If you hover it for a long period of time, Which gives me two flights and the engine gives up, It could be user error, The attempts were getting on the carrier, And back to the runway using VTOL, Ive not been using water either, Never felt need to.

[comie1]

The more I read the more I'm inclined to believe this isn't a bug and is human error. The engin will take damage if you exceed limitations for periods of time. Ive made over 10 vertical takeoffs and landings in one session without this happening. Anytime you get the R or J with markings you are at danger levels.. keeping below these limits will maintain the engine for a longer period of time. The water even when flying really light should be used when you for example go full throttle on a VTOL takeoff exceeding RPM or JPT limits. Monitor your temps and rpm and keep them low as possible at all times, under the situation where the HUD symbology of the R or J appear if possible. When they do... limit your time in your head situations.

[Texac]

I also believe it is more a human error and I think a developer or QA also mentioned this.

 

Page 32 of the Pocket Guide shows the engine limits table as well.

Edited December 3, 2017 by Texac

[DefaultFace]

I'm sure a certain amount of it is human error but as I said I've been taking great care in monitoring JPT and time at or above the power threshholds. I've had several sorties with Sortie max JPT numbers well below the normal lift limits and certainly for less than the time limits stated in the manual. I've also noted OT times of about 4 seconds (seems to be the time it takes between JPT spiking at high power and water kicking in) even with these low JPT maximums. Alot of the times in these sorties I notice the engine needing more power to takeoff or land, needing water injection at weights where it normally doesn't or simply lacking the thrust to hold the aircraft.

[Sandman1330]

I'm sure a certain amount of it is human error but as I said I've been taking great care in monitoring JPT and time at or above the power threshholds. I've had several sorties with Sortie max JPT numbers well below the normal lift limits and certainly for less than the time limits stated in the manual. I've also noted OT times of about 4 seconds (seems to be the time it takes between JPT spiking at high power and water kicking in) even with these low JPT maximums. Alot of the times in these sorties I notice the engine needing more power to takeoff or land, needing water injection at weights where it normally doesn't or simply lacking the thrust to hold the aircraft.

 

I concur. I just spent a good couple hours doing circuits to the boat, very closely monitoring my limits. By the third or fourth circuit, I'm noticing JPTs well above where they were on the first circuit for a given power setting, ultimately I usually crash the third or fourth circuit due to lack of engine power, where I was able to hover previously...

[comie1]

If you guys can get a vid or a trk file up I'm sure they guys could work it out for you .

[eurofor]

Don't have a trk-file right now but I have also experienced this strange behaviour in the engine performance on some of my long flights. Would be interesting to know what's causing it if it's working as intended.

[MikeMikeJuliet]

One thing to note is that if your flight is of any length, you may exceed max continuous power, which is 102% OR 645°C for 15 minutes straight...

 

So if you say you've been flying approximately between 100-105%, remember that you might have been over the 102 mark for too long OR, more likely you have exceeded the 645° limit without noticing.

 

 

I'm not saying this is absolutely the case, but I've found that you need to watch your engine all the time with this bird. The lazy flying allowed by previous "perfect condition" aircraft is really biting back here at least on me.

 

 

Regards,

MikeMikeJuliet

[Texac]

I was testing it an hour ago and almost arrived at the airport until the sim crashed.

 

Flying in the third Quickstart mission climbing to 15000 feet max. with almost 100% RPM, not more and less than around 600 JPT at 400 kts everything was looking good so far a few miles ahead of Beslan.

 

I'll try it again and speed it up a bit.

[3mta3]

The DECS limits the engines RPM and JPT - according to the manual.

 

In any case - even if it were possible to exceed the RPM or JPT limits - the result wouldn't be a engine that can no longer produce normal power - it would just shorten the life of the engine. Meaning it needs to be overhauled sooner.

 

Every jet I've ever flown has some form of engine control that provides protection and often thrust management - so even a firewall forward "all she's got" situation won't result in loss of thrust. Most likely just a borescope after mx downloads the engine data postflight. Worst case a engine change but probably just a inspection based on what limits are exceeded. You are not going to melt a engine by pushing the thrust to max.

 

There is something wrong with the way the engine loses power over time in the current version. It also seems to retain the JPT max from a previous flight even after a restart.

 

Here is the section from the actual AV8B manual.

 

2.3.1.6 DECS Limiting For the F402- -RR- -406 engine the jet pipe temperature (JPT) is limited to 727°C for short lift wet, 703°C for short lift dry, 665°C for Combat, and 625°C for maximum thrust. For the F402- -RR- -408 engine the JPT is limited to 800 °C for short lift wet, 780 °C for short lift dry, 750 °C for combat, and 710°C for maximum thrust. JPT limiting inputs include JPTL switch, gear position, nozzle position, water injection switch position, air data computer (ADC) airspeed, and combat mode switch position. With gear down, or nozzles greater than 16° down, the short lift wet or dry datum is selected depending on the water arming switch position, if the combat mode switch in the main wheelwell is in the ENABLE position. If the combat mode switch is in the DISABLE position, DECS will limit rpm to 99 percent for the - -406 engine and 109 percent for the - -408 engine when above 250 knots. With gear up, nozzles aft, and combat mode switch in the enable position, the maximum thrust or combat datum is selected by the combat select switch. Selecting limiter off, then reselecting limiter on will result in up to 15- -second delay in active limiting of JPT under DECS control. During this time, the pilot must manually maintain JPT limits.

[Texac]

15000 feet max. with almost 100% RPM, not more and less than around 600 JPT

 

Same altitude, JPT temperature, RPM and mission so I did not exceed any of the maximum engine limitations for a to long amount of time.

 

Flying off all the waypoints and landing, the acceleration times of the engine during a second and third RVTO were identical (35-60% - 2.4s) & (60-105% - 2.8s) to the first at the beginning of the flight.

 

When exceeding the Maximum Thrust limit after 15 minutes the Overtemp warning/caution light and tone came up and after that the engine perfomed much weaker.

 

Perhaps this might need some tweaking.

Edited December 2, 2017 by Texac

[DefaultFace]

@3mta3 The harrier actually has a built in JPTL shutoff if you slam the throttle forward hard enough (30-35 lbs of force according to NATOPS). This isn't implemented yet in DCS. I'm not sure to what extent the JPTL is implimented in the Harrier yet either. I've tried turning it off a few times when noticing I've lost thrust to see if it was just the engine overheating and I could force overheat it to get enough thrust to at least survive the landing but it didn't appear to do anything.

 

As for the JPT max if you hit the MPCD buttons above the JPT sortie max you can reset it.

[3mta3]

I see that JPTL throttle override in the manual. Thanks for pointing it out. I don't think that is the problem - it just seems that the power loss is there to "punish" the player (for lack of a better term) for exceeding limits that the DECU should be protecting in the first place. After all - the throttle is only a switch that transmits TLA to the DECU. The DECU controls thrust and maintains the engine within limits - if it is correctly simulated.

 

I understand engine limits very well - and you could exceed the max continuous power time limit. But again that doesn't degrade the power the engine can produce. It just shortens the life of the engine.

 

Somewhere in the Actual manual it even mentions how many minutes less engine life vs JPT.

 

The key point is it is unrealistic for a jet turbine engine to wildly degrade its available thrust in a short time period. Short of taking damage of some sort. The throttle isn't a "destroy engine" switch.

 

Older engines I fly usually just have a higher EGT to produce the same thrust. They don't loose power to the point you cannnot sustain flight. Which has happened to me several times in the curent release of the AV8B.

[Sneak69]

I am thinking its a bug.

 

Sent from my SM-G930W8 using Tapatalk

[jeffdude]

As the title suggests I have been struggling in taking the Harrier out for at least two whole sorties. Be damned if I can get it up and land it for the third time. I'm probably pushing the aircraft to its limits, but then again I also find it irregular that it is acting like this.

 

For example. I load up in the Harrier - I bring the aircraft in the air - standard take-off temp at around 720-711. Everything normal. Fan RPM 100%-108%. Nozzles at 30-35 degrees. After about maybe 20-30 minutes in the air, I return back to base to rearm/refuel.

 

This is where the problem occurs.

 

Taking off for the second time same loadout/fuel (ignoring the fuel bug). Engine Temp is now reaching a whooping 780 degrees. At times over 810 degrees even with WATER switch on H2O. Fan RPM 95-90%. Max Thrust Nozzles at 25-20 Degrees now to compensate the sudden loss of thrust and prevent engine to overheat. (Even the green light won't come on to let me know its cooling the engine). In addition, landing in VTOL would result in insufficient thrust regardless of empty weight and also result in me falling out of the sky into the grass/water. (No stores and roughly 2000 pounds of fuel).

 

I have attempted to alleviate the problem by turning off my aircraft and or repairing my aircraft after every sortie, but the outcome is always the same. The second sortie is usually my last one, if I come back alive that is lmao.

 

I'm assuming it is LARGELY user error and I'm just stupid and missing something. It is also worthy to note that I have also tested it out for a long duration flight with two tanks 11k total fuel and nothing else on stores. And the results were the same. Insufficient thrust for transitioning into a sustainable Hover after spending at least 40 mins+ on a flight for a first time landing. Like the engine itself degrades in flight, very slowly.

 

I've tried looking up problems that plagued the Harrier, like Engine Temperature problems or deflating thrust issues before posting. I haven't found any so I'm still unsure if this is a bug or has been mentioned before or is Known. ...Maybe its a feature...

 

Before anyone asks about water levels and damage from enemy fire. Water capacity is usually the same. 400-500. And no damage sustained on many of my sorties.

 

You mentioned the water didn't come on, may i suggest more throttle, the engine only applies water at the higher settings. If it doesn't come on and you have heat, I may suggest the counter intuitive choice of more throttle.

[Texac]

Taking into account that the aircraft is still in an Early Access state and we now have 3 pages pointing out that the current modeled engine realibilty of the Harrier is probably calculated wrong in the sim, the developers might plan to take care of the situation.

 

Maybe they are already working on a better solution to simulate it realistically on a long term if it isn't correctly modeled at the moment.