Engine power problems: what am I doing wrong?

[Tomsk]

Hi I used to fly the Mirage a lot many years ago, I must have several hundred hours in it. Recently I thought I'd give it another fly after a (very long) break. The plane has changed quite a bit I see: new radios, various displays have changed. Nice to see the progress.

So I thought I'd go fly a pattern in the Mirage Instant Action at Nellis, something I've done hundreds of times in the Mirage in the past. However, I'm finding it doesn't have enough power to hold a level turn on-speed with the gear down at Nellis. As a result my turn from downwind onto base requires me to do it on full afterburner! Even the descent on final down to the runway requires nearlly full military power to hold on-speed correctly. I checked I don't have the speed brake out or anything stupid like that.

The Mirage 2000C never used to do this back in the day. I never had any problems being unable to do patterns with it due to lack of engine power. Hell there's no plane in DCS that I've been unable to hold a level turn with the gear down. This surely can't be realistic, needing to do turns onto the base leg at full afterburner and landing at nearly full military?!

Edited August 23, 2022 by Tomsk

[myHelljumper]

Hi,

We recently updated the engine to be much more realistic in performance as well as failure and damage modeling.

What you are explaining doesn't sound right, there is something wrong with your aircraft. Could you provide us with more information ?

In order to help you we would need to know:

• Internal/External fuel and loadout at the time you did the pattern.
• Speed and bank angle used in the pattern and AoA on final.
• Warning and cautions on the alarm panel.

A video or a track would be even better.

I'm suspecting that your engine switched to the secondary FADEC (CALC SEC) and you didn't rearm it.

Thanks.

Edited August 24, 2022 by myHelljumper

[Tomsk]

Hi, thanks for the reply. This is the "Cold Start" Instant Action in Nevada. I started the jet, took off and did a pattern round the airbase.

• In the Instant Action in Nevada the jet starts pretty heavy: 35,000 lbs with 3 bags and 2 Magics. 
  • I also tried the procedure with the Caucasus Cold Start Instant Action which is 2 Magics, 2 530s and no bags (26,000 lbs).
  • Although this was better than Nellis, it still required some afterburner use to make the turn.
• My procedure was as follows:
  • Towards the end of the downwind put the gear down and move to the correct AoA (FPM in the brackets, near the top).
    • Can't tell you exactly what airspeed this is as I was flying AoA not airspeed, as is typical with modern jets.
  • I did notice that putting the gear down seems to cause a massive increase in drag, far more than other similar aircraft.
  • I then turned onto base whilst holding altitude. Bank angle was I'd guess roughly 20 degrees, not a steep turn. 
  • To hold the turn I had to go full afterburner, even then I couldn't hold altitude while I did it.
  • Then after the turn I did the final descent.
    • AoA was in the bracket, although I found the plane really struggled to hold that needing nearly full military power.
• I believe I did check for warnings/cautions, as I thought something was wrong, but I saw none.

I'll see if I can get a video/track later, although it might have to wait a day or two.

[myHelljumper]

10 minutes ago, Tomsk said:

Hi, thanks for the reply. This is the "Cold Start" Instant Action in Nevada. I started the jet, took off and did a pattern round the airbase.

• In the Instant Action in Nevada the jet starts pretty heavy: 35,000 lbs with 3 bags and 2 Magics. 
  • I also tried the procedure with the Caucasus Cold Start Instant Action which is 2 Magics, 2 530s and no bags (26,000 lbs).
  • Although this was better than Nellis, it still required some afterburner use to make the turn.
• My procedure was as follows:
  • Towards the end of the downwind put the gear down and move to the correct AoA (FPM in the brackets, near the top).
    • Can't tell you exactly what airspeed this is as I was flying AoA not airspeed, as is typical with modern jets.
  • I did notice that putting the gear down seems to cause a massive increase in drag, far more than other similar aircraft.
  • I then turned onto base whilst holding altitude. Bank angle was I'd guess roughly 20 degrees, not a steep turn. 
  • To hold the turn I had to go full afterburner, even then I couldn't hold altitude while I did it.
  • Then after the turn I did the final descent.
    • AoA was in the bracket, although I found the plane really struggled to hold that needing nearly full military power.
• I believe I did check for warnings/cautions, as I thought something was wrong, but I saw none.

I'll see if I can get a video/track later, although it might have to wait a day or two.

Yeah everything looks correct.

I will need a track/video to understand what happens. If you are doing a video, please make sure to activate the control indicator (RCtrl+Enter).

Thanks

[Tomsk]

Thanks, I'll also try it from a hot start. Perhaps I'm doing something wrong during the cold start procedure. I'm not getting any warnings, but that doesn't mean something isn't off somewhere. Will go for a track, I fly VR exclusively so the video tends to look a bit weird anyway.

[Tomsk]

Found time in my break, this was hot start from the runway with 2 tanks. Still requires full burner to hold on-speed in quite a modest level turn.

Recorded in latest Open Beta: Mirage burner turner.trk

Edited August 24, 2022 by Tomsk

[Ramsay]

4 hours ago, Tomsk said:

this was hot start from the runway with 2 tanks. Still requires full burner to hold on-speed in quite a modest level turn.

I think this is to be expected as you are flying/landing much heavier (5.8 fuel remaining) than the uprated MLW

Section 27, pages 661-662 of the current DCS Mirage manual v2.2.0.

This is a real life "overhead break" procedure - as you can see even at the correct landing weight, it's flown much faster (i.e. 200 KIAS downwind leg) than "on-speed AoA"

 

Edited August 24, 2022 by Ramsay

[myHelljumper]

Hi,

What's said above is correct, you are way too heavy to land the aircraft.

Try the same maneuver but under the maximum landing weight and it should work better.

[Tomsk]

On 8/24/2022 at 2:20 PM, Ramsay said:

I think this is to be expected as you are flying/landing much heavier (5.8 fuel remaining) than the uprated MLW

Section 27, pages 661-662 of the current DCS Mirage manual v2.2.0.

This is a real life "overhead break" procedure - as you can see even at the correct landing weight, it's flown much faster (i.e. 200 KIAS downwind leg) than "on-speed AoA"

 

 

Thanks, that's very useful. Are you sure "Maximum remaining fuel" isn't in addition to the "Full internal fuel" specified in the "Clean aircraft" config? Otherwise that would mean that a "Standard air-to-air" config can only make a standard landing if it has less than 1800lbs of fuel left (0.85 tonnes). That would be 25% capacity, almost empty .. you'd only get a couple of attempts at landing before you were out of fuel entirely. Surely almost all landings with combat loadout would then need to be uprated ones? Also the maximum uprated fuel for that config is 3.25 tonnes, that's 7,100 lbs which is essentially full internal capacity. Is it not safe to land the plane at all (i.e. even uprated) with 4 missiles, full internal fuel and an (essentially) empty centre tank?  

EDIT: Hmm looking at it that would make sense with the "Standard air-to-ground" having a normal MLW which is "< 0.5 min. res" which I guess means "minimum reserve". i.e. you'd be below the minimum safe amount of fuel for operating the jet with. That's interesting, I never knew the Mirage was quite so limited on landing weight! I believe the viper (the AC if fly the most) has effectively no maximum landing weight: if you can take off with it you can land with it.

Edited August 25, 2022 by Tomsk