Mirage supercruising?

[Pocket Sized]

So, if the HUD velocity is TAS,

 

It isn't.

[Panthir]

M2K can "supercruise" due to the delta wing arround 40k high. The only problem is that it initially needs AB to go supersonic. Then can supercruise MAX dry low supersonic. Something arround 1.2M if I am right :-).

Edited October 11, 2016 by Panthir

[GGTharos]

No. Just no. You`d need a much more powerful dry-thrust engine for this :) Drag is still very high at M1.2.

 

M2K can "supercruise" due to the delta wing arround 40k high. The only problem is that it initially needs AB to go supersonic. Then can supercruise MAX dry low supersonic. Something arround 1.2M if I am right :-).

[Panthir]

https://m.facebook.com/notes/flying-geeks/aerodynamic-advantages-of-delta-wings/215643998462157/

 

GGTharos read please the 1st paragraph

[Panthir]

The primary advantage of the delta wing is that, with a large enough angle of rearward sweep, the wing’s leading edge will not contact the shock wave boundary formed at the nose of the fuselage as the speed of the aircraft approaches and exceeds transonic to supersonic speed. The rearward sweep angle vastly lowers the airspeed normal to the leading edge of the wing, thereby allowing the aircraft to fly at high subsonic, transonic, or supersonic speed, while the over wing speed of the lifting air is kept to less than the speed of sound. Some other advantages of Delta wings are:-

 

Rise in Transsonic drag is gradual and peak drag in supersonic flight is reduced

[GGTharos]

Somehow that doesn`t look like a performance chart for the Mirage. This might help your argument a bit better. :)

 

Even a drag force or drag coefficient graph would help your argument much better. What you types is really no different between the mirage and the vast majority of other fighters. Delta wings don`t magically make an aircraft super-slick and able to super-cruise.

 

I might add that you`ll one day notice - if you look deep enough - that descriptions of what the peak is doing aren't terribly relevant without other information, nor indeed the complete graph of the coefficient of drag at minimum.

[Panthir]

My dear friend, I can't provide you with a performance chart right now and I don't intend to do it :-) .Eventually, Delta wings have some pros and cons as well. One advantage is the comparative drag reduction while being supersonic due to the fact that eventually the wing is still subsonic. This advantage is significant 40k high. This is the truth my friend, whatever you say. I quit now :-)

[GGTharos]

Again, this is absolutely meaningless.

 

It's like saying that an 11m barrier is lower than a 12m barrier. It's comparatively lower, yes. You still won't be jumping over it :)

 

One advantage is the comparative drag reduction while being supersonic due to the fact that eventually the wing is still subsonic. This advantage is significant 40k high. This is the truth my friend, whatever you say. I quit now :-)

[Ktulu2]

This is the case for any swept wing, not only delta wings. As you said, its all about the flow that is orthogonal to the wing, which any wing that has a sweep angle will reduce.

Edited October 11, 2016 by Ktulu2

[Azrayen]

M2K can "supercruise" due to the delta wing arround 40k high. The only problem is that it initially needs AB to go supersonic. Then can supercruise MAX dry low supersonic. Something arround 1.2M if I am right :-).

 

Chiming in, heard ~the same indeed.

40-45K.

No more than 2 Fox2.

M1.2, perhaps a bit less? Was not specific.

Edited October 11, 2016 by Azrayen

[Bashibazouk]

This is an old thread, but I looked it up because I was surprised to be exceeding Mach 1.02 in level flight at angels 22 without AB. I had two heaters on the outside pylons and an empty pylon in the middle after bombing a runway with BAPs (or whatever they're called). I don't know how realistic this is, or if the indicator in the HUD is correct, but using F3 (external flyby) I was definitely witnessing  the DCS sonic boom. Whether it's accurate or not, the DCS M-2000 will kind of supercruise with the lightest AA combat load.

Now, as I write this I a few things have occurred to me. At Angels 22, it wasn't getting past 1.1 so maybe I was using a ton of fuel, probably less than when using AB but still. It may not be the most efficient way to get around. When I find the time I might see what it's like above Angels 30, maybe it's further away from transonic and thus more efficient. Any other comments, criticism or knowledge is welcome on my part.

 

EDIT - IIRC, I did use AB to get past Mach 1, but it was definitely holding steady without AB at those low supersonic speeds once it was over the worst of the hump.

Edited March 24, 2024 by Bashibazouk

[Galinette]

M1.02 is transsonic, it's not enough for being elligible to the "supercruise" club, especially with virtually no loadout.

 

[Sideburns]

It might be worth testing this after dropping the bombs and also having never had the bombs on the plane but otherwise a similar loadout. A few DCS modules have had weapons drag bugs where using a weapon results in less overall drag then never having carried the weapon in the first place.

[zerO_crash]

The above mentioned refer to a facebook post which is sourced off Wikipedia. People have a funny concept of what constituates a good source. Can't wait till Tiktok becomes the next best around here.

 

In any case, the ability to supercruise is really dependant on two factors: thrust-to-weight ratio and aircraft layout (aerodynamic properties). It isn't however as simple as stating that an aircraft posessing both will be capable of supercruising. It's more individual than that. Fact is, unless a proper CFD simulation, reliable chart is presented or actual pilot (possibly someone knowing one), it's pure speculation.

 

Checked "Manuel Pilote Mirage 2000 C" (don't ask me how I got it, or to post it) and there is no mention of the capability. That doesn't, however, mean anything. An SME could provide valuable input here (to which Razbam should have access) or a confirmation from Razbam. Eventually, there are French forums, where a user might have a friend of a friend in the French Air Force. Until then, speculation.

Edited April 21, 2024 by zerO_crash

[jubuttib]

Would be interesting to have more real life data. The Mirage 2000 is a slippery rascal, as evidence by being rated for mach 2.2 at "high altitude" with an engine rated for 95 kN of thrust, vs. for example F-16 at 2.05 at 40k feet with 130 kN of thrust (rough wiki numbers, please don't shoot me).

[zerO_crash]

I'll pass you on wiki, but in essence, there are far more factors to consider; wing (delta is the best wing for high speeds), engine (not only sheer power, but how well the engine retains its thrust with altitude), aerodynamic design, AOA at speed (distribution of weight & general design), and more.

 

The Mirage 2000C has the Snecma M53-P2. This engine, is a late derivative of the Atar-series of engines, which were built for M2.0+ at high altitudes. In fact, the M53-P2, was initially designated Super Atar 9K50. It was built for M2.5+. This also explains why the engine will take you to the breaking point of the plane (structural strength), without any problems. French have built fantastic series of engines here. For reference, P&W are more balanced. They are tuned for good performance across altitudes and in different regimes, thus aren't exceptional at any particular altitude & speed (they are good overall though).

 

Just to show you how little T/W matters - have a look at SR-71. At full fuel load, it has a T/W of 0.44. You'd think that is horrible, which it is, by any means. However, due to the design of the aircraft (notice how much lift it has with it's body), it manages to reach M3.4+. Another example, MiG-25. It has approximately 0.55 T/W (gross weight - there are variations between the different versions). Imagine that it's capable of M3.2+ (M2.83 limitation, is same as M3.3 for SR-71 - it's a continuous use limit for the airframe to last. (M3.4 on SR-71 was only permitted in one special case, otherwise M3.3 was max.)). 
 

Remember, that just because a engine "can" reach a high speed, if it's not built for it, its service life will be eaten through quickly. Same goes for the airframe. As such, aircraft like SR-71, MiG-25, MiG-21, Mirage F1 & 2000, will last longer in such conditions, because they are built for it. A F-15 or F-16 can manage to reach M2.0 (depending on which versions), but they do it with sheer power. The airframes, are not actually optimized aerodynamically for such flight, which means that there are inefficiencies in the form of drag (trade-offs). Drag -> heat and pressure -> stress on the airframe. Therefore, if you look at how many F-15/F-16 hours have cumulatively been spent at above M1.5+, you'd be surprised just how little it is (maybe a percentile of all hours ever flown, if even that much)). I seem to remember a interview with a F-15C pilot, who claimed that above M1.5 flights, is something, you as a pilot, do possibly once during your training, and that's it. You'll most likely never touch that speed again in your career. 

Edited May 22, 2024 by zerO_crash

[jubuttib]

On 5/22/2024 at 4:48 AM, zerO_crash said:

Just to show you how little T/W matters

FWIW I'm not thinking about thrust to weight at all, more about thrust to size. Aerodynamic forces scale so quickly that I've always considered weight a secondary concern to top speed. Acceleration, sure, but not the primary factor for top speed.

[zerO_crash]

Well, size is everything but, simple size. As you mention, small changes in design, can result in astronomical changes to the airframe performance. I'd drop the thrust, in that equation, as whether we talk acceleration or top speed, it's interconnected. Top speed happens at the moment when acceleration equals zero. More important, is simply the basic construct - airframe. That's what really separates these projects from each other.

 

More interestingly, we don't really understand aerodynamics in the mathematical way that we'd want to. The magnitude of effects from different features on an airframe... There is a reason why wind tunnel and CFD is a core part of the testing. Basically, trial and error, with minimum level of confidence in the actual changes. Last I heard, the F-35C (marines, SVTOL) has a limit on how long it can sustain supersonic (x > M 1.0) speed, due to the vertical stabilizers getting cooked (not tollerating temperature), as well as cracks, deformations and exponentially accelerated wear occuring. You'd expect that with an airframe this expensive, and some 20 years delayed, such basic issues would have been solved. Granted, the topic of aerodynamics itself, is incredibly versed and diversified in the range of speeds/altitudes/pressures/temperatures/etc... That's not even considering building an aircraft.

[jubuttib]

On 5/23/2024 at 5:00 PM, zerO_crash said:

I'd drop the thrust, in that equation, as whether we talk acceleration or top speed, it's interconnected. Top speed happens at the moment when acceleration equals zero.

And acceleration equals zero when thrust forces = drag forces.

EDIT: Man that emoji annoys me... It was supposed to be a simple smile, not a laughing face...

Edited May 27, 2024 by jubuttib

[zerO_crash]