Should the M2KC be able to hold up against the Viper in a 2 circle fights?

[myHelljumper]

Hey everyone,

I just wanted to share the following with you guys

From this video at around 2:15 we can see the following :

400kt, 6.8 g, PS~0.

For this video the Mirage most likely does not have 100% fuel and surely is at least a little bit above sea level.

If we compare with the DCS Mirage:

I find that we are pretty close :).

Edited November 3, 2022 by myHelljumper

[Tom P]

helljumper providing data and has SME(m2000 pilots) feedback for accurate development towards their flight model.  

DCS armchair pilots: "well my buddy said...." 

[TheGopnikTsar]

Funni delta wing and funni engine go brrrrrrrr

[Kev2go]

5 hours ago, 162nd Pete said:

helljumper providing data and has SME(m2000 pilots) feedback for accurate development towards their flight model.  

DCS armchair pilots: "well my buddy said...." 

 

I mean didn't helljumper just admit they have no concrete documentation?  and they  formulated  that "data" based on cobbling together pincemeal sources like some Dogfight videos and some SME opinion?  SO i dont see why people cant question its authenticity  of the new FM change when the data are based on what amount to estimates relative to say an F16 turn rates taken from actual official documentation like a HAF manual.....

 

 

Edited November 4, 2022 by Kev2go

[myHelljumper]

3 hours ago, Kev2go said:

I mean didn't helljumper just admit they have no concrete documentation?  and they  formulated  that "data" based on cobbling together pincemeal sources like some Dogfight videos and some SME opinion?  SO i dont see why people cant question its authenticity  of the new FM change when the data are based on what amount to estimates relative to say an F16 turn rates taken from actual official documentation like a HAF manual.....

While we effectively don't have concrete performance documentation (because none are available to the public), we didn't formulate the FM by only "cobbling together piecemeal sources".

We based the FM on known data points like the video above and procedures like the engine out landing that give us a very good base for what the aircraft should be capable of. We then built the FM following aerodynamic studies to create the coherent and realistic wing. After that we talked with SME about the behavior and performance of the aircraft to fine tune FM where needed.

While I'm sure our FM is not 100% correct to the real aircraft in the whole domain, I think it's a good enough representation and most of all, the closest possible with the data available to us.

We also have demonstrated, using the video above, that the Mirage STR at around sea level and 400 kt is correct while we have yet to see a credible source that would demonstrate that the aircraft performances are incorrect.

But don't get me wrong, I agree that our model is not based on turn rates from actual documentation and thus is not as solid as the DCS F-16 model for example. People are right to question the authenticity of the Mirage FM but we are providing a lot of information to backup our model.

Thanks.

[cmbaviator]

12 hours ago, myHelljumper said:

Hey everyone,

I just wanted to share the following with you guys

From this video at around 2:15 we can see the following :

400kt, 6.8 g, PS~0.

For this video the Mirage most likely does not have 100% fuel and surely is at least a little bit above sea level.

If we compare with the DCS Mirage:

I find that we are pretty close :).

 

Is it normal that i can't see the images ? i would like to see them  Thanks

[myHelljumper]

52 minutes ago, cmbaviator said:

Is it normal that i can't see the images ? i would like to see them  Thanks

I can see them, I don't know why you can't.

Here are the links

Video screenshot: https://cdn.discordapp.com/attachments/1037846602670407700/1037857598881402971/image.png

Mirage turn rate chart a sea level : https://cdn.discordapp.com/attachments/544216334045544448/1016340654353305681/unknown.png

[Despayre]

11 hours ago, Kev2go said:

 

I mean didn't helljumper just admit they have no concrete documentation?  and they  formulated  that "data" based on cobbling together pincemeal sources like some Dogfight videos and some SME opinion?  SO i dont see why people cant question its authenticity  of the new FM change when the data are based on what amount to estimates relative to say an F16 turn rates taken from actual official documentation like a HAF manual.....

 

 

 

 

Ignore the experts and people that have actually flown the planes... and arrive and your own conclusions and then assert them as equally factual... sure, what could go wrong?

On an unrelated note, I have a flat earth to sell you... 

[HWasp]

19 hours ago, myHelljumper said:

Hey everyone,

I just wanted to share the following with you guys

From this video at around 2:15 we can see the following :

400kt, 6.8 g, PS~0.

For this video the Mirage most likely does not have 100% fuel and surely is at least a little bit above sea level.

If we compare with the DCS Mirage:

I find that we are pretty close :).

 

 

Thanks for showing this important data point.

I think it would be important to discuss about fuel state in a bit more detail, because it has a very large impact on this subject. For me it seems like, that the current FM STR at 400 kts is accurate to the video if fuel is assumed to be 100% on take-off. (in that case at 2:15 with constant full afterburner we are at around 77% fuel and STR is around 6,8 G).

So again to be clear,  the FM is only accurate regarding this data point, if we assume, that the demo flight starts with 100% fuel in the video.

I tested the 400 kts STR with different fuel loads, and the difference is of course quite huge. (I used your chart to show the data, I hope, that is no problem)

- at 100% fuel sustained G is 6,5

- at 75% fuel sustained G is 6,9  (in DCS for me take-off + low speed aerobatics with constant full AB for 02:15 takes me to 77% fuel )

- at 50% fuel sustained G is 7,5

- at 25% fuel sustained G is 8,3

According to Mirage pilots, what is the usual take-off fuel for a standard 10 minutes airshow display? Are they using 100%?

Please see the chart attached, STR at the previously mentioned fuel loads marked.

Tracks for the STR at 400 at the mentioned fuel levels.

(the 25% fuel test is a bit crappy because I did not disable G effects, so was blacking out constantly)

M2000STR400kts100_1122.trk M2000STR400kts25_1122.trk M2000STR400kts75_1122.trk M2000STR400kts50_1122.trk

[myHelljumper]

2 hours ago, Despayre said:

 

Ignore the experts and people that have actually flown the planes... and arrive and your own conclusions and then assert them as equally factual... sure, what could go wrong?

On an unrelated note, I have a flat earth to sell you... 

Please guys be respectful.

I welcome constructive discussion and criticism and don't want it to be shut down.

Let's be respectful of everyone and try to move this discussion forward.

[jojo]

1 hour ago, HWasp said:

According to Mirage pilots, what is the usual take-off fuel for a standard 10 minutes airshow display? Are they using 100%?

With the limited amount of internal fuel (3165kg on standard day) and the generous use of after burner, you can expect the plane to start up at 100% fuel.
But "start up + taxi + take off" generally cost about 200kg of fuel.

Edited November 4, 2022 by jojo

[myHelljumper]

1 hour ago, HWasp said:

[...]

Hi,

First I want to thank you for this detailed analysis, it looks well done, pertinent and your questions are interesting.

I will try to answer them and go beyond.

We can be sure that the aircraft starts at around 100% fuel thanks to the displayed Jx at the start of the video: 0.68/0.69. The Jx represents the acceleration of the aircraft and is very important because it indicate the good health of the engine. For a standard atmosphere, 15 °C, sea level and no payload, the Jx should be at around 0.68.

Thanks to the above we know that the conditions are likely close to a standard atmosphere and 15 °C.

Now let's talk about altitude. At 2:17, just after the sustained turn, we can see that the aircraft is at around 800 ft barometric (3000 ft radar but the radar altimeter must be displaying incorrect information) and from other parts of the video, I can guess that the airbase is the BA115 Orange-Caritat located at 200 ft MSL.

So the aircraft is flying at around 1000 ft MSL, I find that at that altitude, standard atmosphere, 15 °C, 75% fuel the aircraft can sustain 6.9 g.

Now let's talk about temperature. The M53-P2 is very susceptible to temperature changes as a 15 °C increase in temperature reduces the engine thrust by ~5%.

If I test at 20°C with a standard atmosphere, 75% fuel the aircraft can sustain 6.8 g.

I find that even allowing reasonable deviation, the module is deviating at a maximum of 0.1 g from the video. Let's also take into account that in the video, the pilot is not aiming for a perfect sustained turn and we can see in the screenshot that he is gaining a little bit of speed (acceleration chevrons above the FPM). A perfect sustained turn would result in more load factor.

I hope this helped to demonstrate that our model is coherent with the real performances of the aircraft, I'm open to continue talking about this video or about other data-points that we have like the engine out landing procedure to further demonstrate the accuracy of our model.

Edited November 4, 2022 by myHelljumper

[HWasp]

14 minutes ago, myHelljumper said:

Hi,

First I want to thank you for this detailed analysis, it looks well done, pertinent and your questions are interesting.

I will try to answer them and go beyond.

We can be sure that the aircraft starts with 100% thanks to the displayed Jx at the start of the video: 0.68/0.69. The Jx represents the acceleration of the aircraft and is very important because it indicate the good health of the engine. For a standard atmosphere, 15 °C, sea level and no payload, the Jx should be at around 0.68.

 

Thanks for the answer!

I still have a problem with this part, because you are using a single parameter to check 2 other. We should know either the fuel state or the temperature to make a 100% assumption.

I have just made a take-off in DCS with temperature set to 30 Celsius and 80% fuel. Jx is exactly 0.68.  If this display is during summer, then this is still a possible combination.

M2000_30Celsius_Jx068_1122.trk

[myHelljumper]

21 minutes ago, HWasp said:

Thanks for the answer!

I still have a problem with this part, because you are using a single parameter to check 2 other. We should know either the fuel state or the temperature to make a 100% assumption.

I have just made a take-off in DCS with temperature set to 30 Celsius and 80% fuel. Jx is exactly 0.68.  If this display is during summer, then this is still a possible combination.

M2000_30Celsius_Jx068_1122.trk 408.3 kB · 0 downloads

I find it unlikely that the aircraft would start from anything else than 100 on the pad as per SOP. After that as JoJo said 200 kg is coherent.

Unfortunately we can't know for sure unless we ask the pilot from the video.

I'll test 30 °C turn performance a little bit later.

Edit: I personally find it more likely that the aircraft started at 100% fuel as its the SOP and a lots of performances checks assumes this fuel state for the aircraft. But you are free to disagree :).

Edited November 4, 2022 by myHelljumper

[HWasp]

12 minutes ago, myHelljumper said:

I find it unlikely that the aircraft would start from anything else than 100 on the pad as per SOP. After that as JoJo said 200 kg is coherent.

Unfortunately we can't know for sure unless we ask the pilot from the video.

I'll test 30 °C turn performance a little bit later.

Airshow demos are not really standard ops, afaik demo flights are often started with less than maximum fuel for the obivious performance benefit, if safety permits. 

Unless one of your Mirage pilot contacts says for 100% they would never ever do this for a certain reason, I think the possibility should be considered.

I did play around flying roughly similiar profiles to the video, with lots of AB and, I think it would be possible to fly this demo starting around 2500 kg and finish with 500+ kg. I would consider that safe.

 

 

[Galinette]

1 hour ago, HWasp said:

Airshow demos are not really standard ops, afaik demo flights are often started with less than maximum fuel for the obivious performance benefit, if safety permits. 

Unless one of your Mirage pilot contacts says for 100% they would never ever do this for a certain reason, I think the possibility should be considered.

I did play around flying roughly similiar profiles to the video, with lots of AB and, I think it would be possible to fly this demo starting around 2500 kg and finish with 500+ kg. I would consider that safe.

 

 

It has been asked to a Mirage pilot already, no, Mirage 2000's are always filled to 100%. And confirmed with 100% confidence that this demo wasn't an exception.

Also when doing a partial fill you can't know accurately how the fuel will distribute in the various tanks, so you can have imbalance, and the gauge will be wrong (since the internal level is extrapolated from the fuselage tank level gauge, wing tanks having no gauges).

So it's just not possible.

On the other hand partial external tank fill is in the procedures (and actually done to adjust T/O weight)

Edited November 4, 2022 by Kercheiz

[HWasp]

6 minutes ago, Kercheiz said:

It has been asked to a Mirage pilot already, no, Mirage 2000's are always filled to 100%. And confirmed with 100% confidence that this demo wasn't an exception.

 

Understood, thanks.

[Kev2go]

 

20 hours ago, myHelljumper said:

While we effectively don't have concrete performance documentation (because none are available to the public), we didn't formulate the FM by only "cobbling together piecemeal sources".

We based the FM on known data points like the video above and procedures like the engine out landing that give us a very good base for what the aircraft should be capable of. We then built the FM following aerodynamic studies to create the coherent and realistic wing. After that we talked with SME about the behavior and performance of the aircraft to fine tune FM where needed.

While I'm sure our FM is not 100% correct to the real aircraft in the whole domain, I think it's a good enough representation and most of all, the closest possible with the data available to us.

We also have demonstrated, using the video above, that the Mirage STR at around sea level and 400 kt is correct while we have yet to see a credible source that would demonstrate that the aircraft performances are incorrect.

But don't get me wrong, I agree that our model is not based on turn rates from actual documentation and thus is not as solid as the DCS F-16 model for example. People are right to question the authenticity of the Mirage FM but we are providing a lot of information to backup our model.

Thanks.

 

Ok i appreciate the clarification and the transparency on how FM adjustments was made.

[HWasp]

13 hours ago, Kercheiz said:

It has been asked to a Mirage pilot already, no, Mirage 2000's are always filled to 100%. And confirmed with 100% confidence that this demo wasn't an exception.

Also when doing a partial fill you can't know accurately how the fuel will distribute in the various tanks, so you can have imbalance, and the gauge will be wrong (since the internal level is extrapolated from the fuselage tank level gauge, wing tanks having no gauges).

So it's just not possible.

On the other hand partial external tank fill is in the procedures (and actually done to adjust T/O weight)

 

 

Thanks again for the detailed answers.

I really like the module, even though I did not fly it a lot nowadays, the constant stream of updates, fixing the low speed behaviour, are really great things, overall I consider it great quality. Please don't get me wrong for continuing to press this possible issue here, even though the very detailed answers, looking the HUD tape video in more detail and testing it against DCS raised further questions for me.

1. I see you are treating the chevrons signaling speed change as a perfect indicator, but is that really perfect enough to deduct STR using it when the pilot just pulls through the range?

Here is what I mean: 

just before 2:15 (the screen posted by myHelljumper) there is another instance of the chevrons crossing the FPM, but with a much lower G value.

There at 2:13 vertical speed is also very low, chevrons are almost on the FPM but G load is only 4,8G  (399 kts)

Please see screenshots attached.

 

For me it seems, that when the pilot is pulling through the STR range dynamically, the chevrons might not be accurate enough to indicate the PS0 moment during the maneuver:

 

Edited November 5, 2022 by HWasp

[HWasp]

Another interesting data point for me is at 02:03, where the pilot performs the only almost horizontal sustained turn for a short time, so speed is stable there actually, and not just going through the range quickly.

There, with a very subtle climb rate, G sustained is 4,7-4,8G  

I tried to replicate this as close as I could in DCS, with 86% fuel load (I figured, 2 minutes of AB would get me there at that point), and DCS value is different, overperforming a bit.

So for me there is 5,4 G vs 4,8 at a slightly lower speed and a very little bit higher V/S 

 

For me this 02:03 moment is the closest thing to an actual sustained turn, even though it's quite short, but speed is finally stable for a bit, and not just going through the range in a single screen

Edited November 5, 2022 by HWasp

[HWasp]

One further point against the chevrons for me is the pull at 02:10

Please see the screens: 

At 02:10 Speed is 409 and chevrons are indicating a large increase

At 02:11 Speed is already dropped to 406, but the chevrons have just only reached the FPM

This tells me, that there is a little delay in the indication, so I think there is a possibility of error while using the chevrons to determine the moment where PS=0. 

In this case, because your data point is at a moment, where G load is being increased quickly, I think at the moment where the chevrons indicate Ps0, we are already beyond that in the video.

 

 

Edited November 5, 2022 by HWasp

[Galinette]

One important detail, the engine in the video is likely a M53-5 which has less thrust than the M53P2 modelled in DCS.

Source : pilots, terrain (orange), aircraft (B&W -> twin seater), date (<2007), and date of M53P2 introduction on twin seaters in Orange.

[Coxy_99]

Youtube video's are not data.

[HWasp]

2 minutes ago, Kercheiz said:

One important detail, the engine in the video is likely a M53-5 which has less thrust than the M53P2 modelled in DCS.

Source : pilots, terrain (orange), aircraft (B&W -> twin seater), date (<2007), and date of M53P2 introduction on twin seaters in Orange.

Ok, thanks, but how much is the difference?

The screen from the video was shown by myHelljumper to validate the current STR.

 

My point, to summarize is: When the pilot increases the G-load at a high rate (as it is the case with the 02:15 screenshot), the chevrons are lagging behind slightly, and at the point the screenshot was made, we are already beyond the G load for sustained turn at that speed.

We can see that happen in the other direction as well, when the pilot unloads at 02:13 and G is only 4,8 while chevrons indicate Ps0. That would also be an incorrect data point to the opposite direction.

 

The only moment I found in the video, where speed is reasonably stable for some time in a close to horizontal turn, is the turn at 02:03. 

Please consider this turn as a data point instead of the one shown previously, even though there is a around 1000 feet per minute climb there, this might be the most accurate.

 

1 minute ago, Coxy_99 said:

Youtube video's are not data.

How on Earth would a HUD footage with speed, g load, etc shown not be usable data???

This is usable, we just need to be careful about certain things, like lagging indicators.

[Galinette]

35 minutes ago, HWasp said:

Ok, thanks, but how much is the difference?

About +10% thrust with full AB