Very high unintended aoa acts like speedbrake...

[Viking 1-1]

Hey guys,

 

after purchasing the Mirage I'm trying to get a hang of everything, but now I'm just focussing on Air to Air which is what this jet was made for. On my flight today I discovered a strange behaviour/problem:

 

I was climbing to around 45.000ft and wanted to establish my CAP on that level, but my speed dropped like hell and I had problems to keep the jet on this height. When I looked outside I saw that the slants (or whatever they are called in the mirage) where fully deployed and my aoa was around 10!

 

That worked like a huge speedbrake so I was constantly loosing speed, thus struggling more. When I lit the burner again, and gathered speed the aoa went back normal, so did my speed. But as soon as I went out of the burner, same again: Drop in speed, slants, aoa, more drop in speed...

 

So I'm pretty sure I'm doing something wrong, but what? Any tips and tricks are very welcome since I really like this jet and want to understand it better.

Edited March 14, 2021 by Viking 1-1

[jojo]

25 minutes ago, Viking 1-1 said:

So I'm pretty sure I'm doing something wrong, but what? Any tips and tricks are very welcome since I really like this jet and want to understand it better.

 

 

Yes, you wanted to establish a cap pattern at FL450 

 

If you fly that high, it's just for straight path. Find me another fighter in game performing CAP pattern at FL450...

So flying that high depends on you weight. What was your weapon load and fuel state ?

[Viking 1-1]

17 minutes ago, jojo said:

 

Yes, you wanted to establish a cap pattern at FL450 

 

If you fly that high, it's just for straight path. Find me another fighter in game performing CAP pattern at FL450...

So flying that high depends on you weight. What was your weapon load and fuel state ?

I was told to always fly high in mirage

 

I had 2 Fox 2 and nothing else remaining, maybe 2200 fuel...

 

[TLTeo]

Fly high doesn't mean try to orbit as close as possible to the service ceiling and yes, at high AoA a tailless delta wing produces lots of drag. That's perfectly normal.

[jojo]

18 minutes ago, Viking 1-1 said:

I was told to always fly high in mirage

 

I had 2 Fox 2 and nothing else remaining, maybe 2200 fuel...

 

 

Yes sure, you can cruise that high (which is already not that bad), but you will have very little turning margin.

[Viking 1-1]

Ok.

 

So you see. Answer was simple:

 

What am I doing wrong? You are too high!

 

Copy.

 

 

[razo+r]

32 minutes ago, Viking 1-1 said:

Ok.

 

So you see. Answer was simple:

 

What am I doing wrong? You are too high!

 

Copy.

 

 

 

Depends.

 

For cruising or doing CAP in general, yes.

 

For multiplayer no. People are regularly flying at 50'000ft or so just for one opportunity to kill some other people. After they are spottet up there though, life gets hard for them.

[unlikely_spider]

17 minutes ago, razo+r said:

 

Depends.

 

For cruising or doing CAP in general, yes.

 

For multiplayer no. People are regularly flying at 50'000ft or so just for one opportunity to kill some other people. After they are spottet up there though, life gets hard for them.

Yeah, I'm trying to adjust my mentality. For a decade I've been a warbird pilot, and am learning BVR combat recently. The old pre-cold war adage of "altitude is life insurance" doesn't seem to apply, at least as much. I'm trying to reconcile the fact that finding contacts low (against the ground) is tough, while up high you're easy to spot. And at the same time missiles like height, so you want to be as high as possible when firing for better missile performance. It's a nut I have yet to crack in my mind.

 

Edit - and, yes, I asked a similar question in the F-14 section about the Case 1 procedure where you sweep wings back in order to slow down. That was counter-intuitive to me as well, but is a lesson that delta configurations create much drag at high AoA.

Edited March 13, 2021 by unlikely_spider

[TLTeo]

To be precise, a more swept wing and especially a big delta wing requires more AoA to generate a given amount of lift (compared to, say, a straight wing in a warbird), and drag increases with higher AoA.

Edited March 13, 2021 by TLTeo

[Viking 1-1]

3 hours ago, jojo said:

 

Yes, you wanted to establish a cap pattern at FL450 

 

If you fly that high, it's just for straight path. Find me another fighter in game performing CAP pattern at FL450...

So flying that high depends on you weight. What was your weapon load and fuel state ?

But still the question:

 

At this height only with full burner? I mean I had the speeddrop with the high aoa as soon as I went out off burner, but still full mil...

[jojo]

14 hours ago, Viking 1-1 said:

But still the question:

 

At this height only with full burner? I mean I had the speeddrop with the high aoa as soon as I went out off burner, but still full mil...

No, that is weird, you should be able to cruise at MIL power.

But doing a 180° turn without burners would take ages.

Edited March 14, 2021 by jojo

[Viking 1-1]

You see, that was my problem.

 

As soon as I went from burner to full mil my speed dropped below 200kts and the crazy aoa started. Only way to get rid of was to go full burner again, which I say is no normal behaviour...

 

Very strange, who knows what I did wrong prior... Will test again and see if I can get to a normal cruise at high altitude 

18 hours ago, TLTeo said:

Fly high doesn't mean try to orbit as close as possible to the service ceiling and yes, at high AoA a tailless delta wing produces lots of drag. That's perfectly normal.

I do know that high aoa produces lot of drag.

 

I would like to know how to get rid of that high aoa without being in Burner all the time.

Edited March 14, 2021 by Viking 1-1

[jojo]

I started FL360 with empty external tank (to simulate start up, take off and climb).

Then I climbed with burners to FL450. Indeed, with the external tank it will slow down.

 

I dropped the bag, the plane settled speed as you can see in attached pictures.

But if you want to fly high, you will better from FL360 to FL400 than above.

[El Chapo]

This is the limit of the flight model. 

A M2000 can obviously sustain a FL400+ with external tanks and no afterburner...

RTB FL495 is fairly usual on a high low high profile. 

But that's true that the margin is sometimes tiny. 

[jojo]

30 minutes ago, Габихан said:

This is the limit of the flight model. 

A M2000 can obviously sustain a FL400+ with external tanks and no afterburner...

RTB FL495 is fairly usual on a high low high profile. 

But that's true that the margin is sometimes tiny. 

 

Yep, something like that ? 

 

 

 

But I think this is a very specific case where the plane needs burners to get there and then can sustain it in MIL power (and light configuration).

Edited March 14, 2021 by jojo

[El Chapo]

True, you need to climb with AB but it's not a problem since it is the most efficient flight profile... 

As soon as you have to fly let's say over 120Nm to RTB, climbing with AB to FL450 and flying home at M0. 95 is more fuel efficient than any other profile. 

And it is sustainable with empty external wing tanks and Magic 2, or with S530 and centerline tank. 

Edited March 15, 2021 by Габихан

[jojo]

1 hour ago, Габихан said:

True, you need to climb with AB but it's not a problem since it is the most efficient flight profile... 

As soon as you have to fly let's say over 120Nm to RTB, climbing with AB to FL450 and flying home at M0. 95 is more fuel efficient than any other profile. 

And it is sustainable with empty external wing tanks and Magic 2, or with S530 and centerline tank. 

 

Thanks for the input

 

I was also wondering about the trick to sustain M0.99 like on the picture above. Probably no external tank though...

Edited March 15, 2021 by jojo

[TLTeo]

On 3/14/2021 at 7:04 AM, Viking 1-1 said:

 

I would like to know how to get rid of that high aoa without being in Burner all the time.

I mean, looking at those DCS screenshots, the jet at FL450 is flying at Mach 0.92 but IAS is only like 250 knots. That means your wing is already doing lots of work to just keep the plane in a straight line, so if you want to orbit during a CAP you need to ask the wing to produce very, very little additional lift (ie, a very wide orbit with a gentle angle of bank). If you try to turn tighter then you're back to needing high AoA, which you'll only be able to maintain in burner.

 

TLDR is, maneuverability sucks at FL450 with any jet, moderate your expectations and you won't be disappointed

Edited March 15, 2021 by TLTeo

[arnokm]

I also like the High Altitude strategy with M2000.

I found FL400 is sufficient to be above contrailing (in game), you can maintain this altitude with center tank (~3500kg remaining) 2xSuper530 & 2xMAGIC without afturburner.

Doing BARCAP at FL400 for 2h can be boring...

Accelerating to 1.7M takes more time at FL450 than at FL400.

It is faster to push to 500KIAS between FL400..FL360 (descending) and then get up to FL520 at iso IAS to intercept enemies (game experience but old jet tactic to pass the sound barrier).

It is very fuel efficient compared to any other aicrafts in game, ~180kg/min, which gives 10 to 15min of high speed action before RTB / tanker.

 

[ZHeN]

after 5+ years of mirage'ing in DCS I've settled @ FL410 for optimum acceleration to high mach. once you reach FL560, you can go idle and stay supersonic for a very long while in a very shallow dive back to 41kft. Didn't try flying level at FL500 in MIL power though, but I don't really doubt it wouldn't be an issue after diving at high mach from FL560

Edited March 22, 2021 by ZHeN