Mirage disintegrated while pursuing maximum level speed at 45,000' altitude

[Pzkfw]

I just attempted to max the speed in the Mirage at 45k alt. The aircraft reached mach 2.3 and continued to slowly accelerate... eventually, the left wing ripped off. No aerobatics were done, this was in level flight. My understanding is that the Mirage's maximum speed is mach 2.2.

 

Is this a feature or a bug?

[jojo]

I just attempted to max the speed in the Mirage at 45k alt. The aircraft reached mach 2.3 and continued to slowly accelerate... eventually, the left wing ripped off. No aerobatics were done, this was in level flight. My understanding is that the Mirage's maximum speed is mach 2.2.

 

Is this a feature or a bug?

 

The maximum allowed speed is officially 750kt CAS (safety margin).

It is known to have tested without issue up to 800kt.

 

In ISA conditions your M2.3 at 45 000ft would be 843kt.

 

I think we can call that a feature :thumbup:

 

But climb 10 000ft more and you will be only doing 702kt. Should be OK.

[Mars Exulte]

[Nooch]

I read that in the Mirage IV, the airframe would start to cook passing the max allowed airspeed (Mach 2.2 like the Mirage 2000). The pilot would experience a burning smell and even see smoke in the cockpit at Mach 2.5. It's very likely that the same thing would happen in the Mirage 2000, instead of its wings ripping out. But hey that's just my educated guess.

[jojo]

I read that in the Mirage IV, the airframe would start to cook passing the max allowed airspeed (Mach 2.2 like the Mirage 2000). The pilot would experience a burning smell and even see smoke in the cockpit at Mach 2.5. It's very likely that the same thing would happen in the Mirage 2000, instead of its wings ripping out. But hey that's just my educated guess.

 

You’re probably right. But how would you simulate the burning smell in DCS ? :lol:

[Sierra99]

But did your parachute work?

[The Integrator]

The maximum allowed speed is officially 750kt CAS (safety margin).

It is known to have tested without issue up to 800kt.

 

In ISA conditions your M2.3 at 45 000ft would be 843kt.

 

I think we can call that a feature :thumbup:

 

But climb 10 000ft more and you will be only doing 702kt. Should be OK.

 

Forgive my ignorance but why are aircraft structural limits in terms of calibrated airspeed? Wouldn't indicated airspeed make more sense since that's a more direct measure of how much air is hitting the airframe in a given time, and so a better measure of the stress on the airframe?

[jojo]

In fact, the real limit for a supersonic aircraft is temperature.

These speeds are just guidelines for the pilot, and the Mirage HUD display CAS.

 

Have you looked for the definition of Calibrated Air Speed ?

[chaos]

Forgive my ignorance but why are aircraft structural limits in terms of calibrated airspeed? Wouldn't indicated airspeed make more sense...

 

Calibrated airspeed is the same as Indicated airspeed but corrected for position error (it’s “true indicated airspeed” if you will). You’re right that that is the number you should be looking for with regards to structural limits...

[NeilWillis]

I suppose you could simulate the burning smell by having a peripheral that sets fire to your gaming seat when certain parameters are met?

 

It'd be far more realistic, so why not? :music_whistling:

[The Integrator]

In fact, the real limit for a supersonic aircraft is temperature.

These speeds are just guidelines for the pilot, and the Mirage HUD display CAS.

 

Have you looked for the definition of Calibrated Air Speed ?

 

Calibrated airspeed is the same as Indicated airspeed but corrected for position error (it’s “true indicated airspeed” if you will). You’re right that that is the number you should be looking for with regards to structural limits...

 

Is it not the case that calibrated (or true) airspeed, TAS, is the IAS accounted for calibration errors, air density, temperature etc. and wind? In other words, in zero wind conditions, it is the same as GS. This means that even if I am in a region of very low air pressure my TAS will not change compared to a region of very high air pressure, my IAS will. Surely then IAS is the best measure of dynamic pressure (which is what the pitot tubes and hence IAS are really measuring) and hence of airframe stress?

Edited October 9, 2018 by The Integrator

[jojo]

I don't see it that way.

 

Yes, IAS is better limit than TAS for airframe stress.

But IAS still has instrumental error.

CAS is corrected of these errors.

 

Anyway, as I said above, the limit isn't speed but temperature (airframe & engine).

This isn't your Cessna.

 

Mirage IV was famous for being able to melt her antennas...

After some threshold speed, the plane would accelerate in supersonic without AB, and the pilot had to throttle back.

 

I bet it's the case for many supersonic aircrafts in high altitude (at least with clean airframe)

[Fishbreath]

Is it not the case that calibrated (or true) airspeed, TAS, is the IAS accounted for calibration errors, air density, temperature etc. and wind?

 

 

No. Calibrated airspeed is not true airspeed. CAS is IAS corrected only for instrument and position errors, not for air density, temperature, and wind.

[The Integrator]

Alright, I think the main issue here is that I have assumed that CAS and TAS are the same, it seems I misread a few definitions. If that's the case then we are discussing a semantics issue and not anything really fundamental. If we take the definition as given by Fishbreath above then sure CAS is a better measurement to use. I think we are all fundamentally agreeing with each other but using different terminology for the same thing.

 

P.S. of course the real limit is temperature, this isn't my first rodeo :p , but that's not really the issue I'm getting at.

Edited October 10, 2018 by The Integrator

[jojo]

Ok, so back to message #2: you were in over speed by 93kt.

Maybe the “punishment” is excessive, yet you have to want it to go that fast. Easy to avoid...

[Eldur]

You’re probably right. But how would you simulate the burning smell in DCS ? :lol:

 

By somehow making the hardware burn through

 

You'd probably never ever won't exceed Vne after that

[Dirty Rotten Flieger]

Wow "true" indicated airspeed sounds funny. It's like objective, subjective opinion.

 

I thought CAS was a more precise TAS. Now I know better.

 

I heard the Mig23 was limited to 2.3 Mach because the canopy would implode! I wonder who found that out?!