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

[HWasp]

24 minutes ago, myHelljumper said:

No, thrust is not static and changes with speed and altitude.

We know the M53-P2 thrust profile from publicly available information, we don't know about the M53-5 thrust profile.

 

Also, even though I understand now, what Kercheiz said about the signs, that show, it is a B, and while I trust his knowledge of course, that is not 100% evidence, although it could be very likely.

if Jx=0,68, what are the chances, that temperature there is just right for the B to match the C's acceleration exactly. Of course it can happen, but still...

[myHelljumper]

23 minutes ago, HWasp said:

Ok, that is understandable, but given the comlete lack of data otherwise, it might still be better to assume, that it has similiar thrust profile, and use that, (I really wouldn't think, that a slightly improved version of the same, with the same intake, etc, would be that completely different...)

Again, I really can't see how the break procedure can help us with this +/-0,5-0,7G difference. Especially with the airbrakes involved. It works, of course, but my problem is with drag between 5 - 12-ish AoA clean. I can't test that with airbrakes out at all....

 

 

As I said we are sure that the airbrakes efficiency is correct, then the only other variable is the aircraft drag with AoA.

The Jx being similar does not mean anything temperature wise as we don't know the reference Jx for a M53-5 engine.

Every data point for the 2000C with M53-P2 engine that I've shared is working with our model, and the only thing you choose to use as a reference an aircraft with another engine. It only means that the module should be capable of at least 4.8 g at 400 and 340 kt.

We can't share more than what we did already so you guys will have to use this information to make your opinion.

Edited November 6, 2022 by myHelljumper

[HWasp]

17 minutes ago, myHelljumper said:

As I said we are sure that the airbrakes efficiency is correct, then the only other variable is the aircraft drag with AoA.

 

 

That is certainly wrong, as this type of airbrake does disturb the airflow and may be even altering vortex forms and generation, so the whole system might act differently compared to clean.

Also, this is not even a precision manuever, it's just an overhead break. All kinds of variables there, great for testing against gross errors, but otherwise...

[HWasp]

22 minutes ago, myHelljumper said:

 

The Jx being similar does not mean anything temperature wise as we don't know the reference Jx for a M53-5 engine.

 

M53-5 has 8-10% less thrust than P2, right? This means acceleration will be less if T=15C, so Jx< 0.68

Previously you have mentioned, for this engine 15C temp increase is roughly -5% thrust

That means, that if you want to make up for the difference with temperature, then this should be a winter video, with temps around 0 Celsius at least.

 

So actually with that in mind, since foliage is visible in the vid, and it does not look like winter to me, this could still be a C model with non-standard B/W camera...

This would be best case scenario for everyone, since even though it means the necessity of another round of tuning, but finally there would be some really solid evidence for STR, and also probably this heavily debated subject about STR could be put to rest, and you guys could focus on my new MiG-23

[myHelljumper]

3 minutes ago, HWasp said:

M53-5 has 8-10% less thrust than P2, right? This means acceleration will be less if T=15C, so Jx< 0.68

Previously you have mentioned, for this engine 15C temp increase is roughly -5% thrust

That means, that if you want to make up for the difference with temperature, then this should be a winter video, with temps around 0 Celsius at least.

 

So actually with that in mind, since foliage is visible in the vid, and it does not look like winter to me, this could still be a C model with non-standard B/W camera...

So you are now choosing to ignore direct pilot feedback that indicates that this is not a 2000C but rather a 2000B with a M53-5 engine to make the video align with your views ? Rather than concluding that we cannot use this video as a source for STR ?

[Galinette]

About removing some L/D ratio artificially between 5 and 12 degrees AoA, besides giving the CL and CD an unrealistic shape, this has the effect of loosing the ability to dry cruise at FL500 where some loadouts that can do it and some can't. The margin is extremely tight there and this is an important feature. Plus giving a weird effect with the chevrons that seem to "fall" when smoothly increasing the load factor during a turn, which is also not observed IRL.

I can't describe the few hundredth hours spent at studying it, but we have thought all of this.

Also about the Jx... I think (but it would need a confirmation) the nominal values are not an average, but a decision minimum. Actual value vary on every engine. And, we are just at this value in the current module.

[HWasp]

12 minutes ago, myHelljumper said:

So you are now choosing to ignore direct pilot feedback that indicates that this is not a 2000C but rather a 2000B with a M53-5 engine to make the video align with your views ? Rather than concluding that we cannot use this video as a source for STR ?

No, I gave you some numbers, that seem to line up.

Is Jx value showing acceleration? Is the -5 engine is weaker, by 10%? How does a weaker engine affect acceleration? Does temperature affect thrust? 

 

If -5 has 10% less thrust than P2, at 15C, Jx will be noticably lower. 

You said 15C difference causes around 5% thrust difference for the engine--->> need a LOT of temperature correction to make up for the 10%, (-15C just going by your numbers )

I simply just used the information You have given me, and they seem plausible to me.

 

Edited November 6, 2022 by HWasp

[myHelljumper]

2 minutes ago, HWasp said:

No, I gave you some numbers, that seem to line up.

Is Jx value showing acceleration? Is the -5 engine is weaker, by 10%? How does a weker engine affect acceleration? Does temperature affect thrust? 

 

If -5 has 10% less thrust than P2, at 15C, Jx will be noticably lower. 

You said 15C difference causes around 5% thrust difference for the engine--->> need a LOT of temperature correction to make up for the 10%, (-15C just going by your numbers )

I simply just used the information You have given me, and they seem plausible to me.

 

 

And you are ignoring all the other facts that indicates that this is a 2000B with a M53-5.

The 5% per 15°C is true for the M53-P2, I don't know about the M53-5.

[HWasp]

7 minutes ago, Kercheiz said:

About removing some L/D ratio artificially between 5 and 12 degrees AoA, besides giving the CL and CD an unrealistic shape, this has the effect of loosing the ability to dry cruise at FL500 where some loadouts that can do it and some can't. The margin is extremely tight there and this is an important feature. Plus giving a weird effect with the chevrons that seem to "fall" when smoothly increasing the load factor during a turn, which is also not observed IRL.

I can't describe the few hundredth hours spent at studying it, but we have thought all of this.

I understand, it is complicated.

Are you sure, a Cd increase causing a 0,5-0,7 G sustained G drop at around 12 AoA would distort that much? Again I'm thinking about relatively minor differences.

[Galinette]

2 hours ago, HWasp said:

 

Yes, and also to stay reasonably close to the best glide speed and not end up with a whole lot of induced drag at low speed range of the drag curve.

 

Look, I can fly the whole thing between 170 and 180 kts easily. (And still have hydraulics in DCS, but this is a different subject then)

 

The video looks like a partial engine failure, someone in the description says it was a control unit malfunction, so it's not a complete loss off thrust. How is that relevant for glide ratio?

Here is the same slowing below 180 already at 10000

M2000_engine_out_proc_err_180_alltheway_1122.trk 1.03 MB · 0 downloads

You need to switch off engine at 30000ft, 40NM from runway, and have slats disabled For this test. Also, it's not 10% engine required to keep hydraulics but 30%. And yes it's not yet modelled properly (big realistic elec+hyd overhaul planned)

6 minutes ago, HWasp said:

I understand, it is complicated.

Are you sure, a Cd increase causing a 0,5-0,7 G sustained G drop at around 12 AoA would distort that much? Again I'm thinking about relatively minor differences.

That's more than 10% drag or lift change, it's huge.

Edited November 6, 2022 by Kercheiz

[HWasp]

 

6 minutes ago, myHelljumper said:

And you are ignoring all the other facts that indicates that this is a 2000B with a M53-5.

 

I'm not ingoring anything, I brought up points that might prove otherwise. 

[HWasp]

34 minutes ago, Kercheiz said:

About removing some L/D ratio artificially between 5 and 12 degrees AoA, besides giving the CL and CD an unrealistic shape, this has the effect of loosing the ability to dry cruise at FL500 where some loadouts that can do it and some can't. The margin is extremely tight there and this is an important feature. Plus giving a weird effect with the chevrons that seem to "fall" when smoothly increasing the load factor during a turn, which is also not observed IRL.

I can't describe the few hundredth hours spent at studying it, but we have thought all of this.

Also about the Jx... I think (but it would need a confirmation) the nominal values are not an average, but a decision minimum. Actual value vary on every engine. And, we are just at this value in the current module.

 

Could you please tell me a possible FL500 loadout? Thanks!

Regarding the chevrons: I think they don't follow the changes perfectly intantenously in the HUD footage. There seems to be a maximum speed, at which they move, so during a high G-onset rate they are a bit late. Looking carefully at the video you can see at high G-onset turns, that the speed is already decreasing while the chevrons still indicate an increase.

That was my main point, why the initially claimed G at Ps0 is not valid, because the chevrons are late and plane is already beyond Ps0 when they arrive at the FPM.

[Galinette]

29 minutes ago, HWasp said:

 

Could you please tell me a possible FL500 loadout? Thanks!

 

Two wing tanks, it should start being able to dry cruise below 2T internal fuel

[HWasp]

2 hours ago, Kercheiz said:

Two wing tanks, it should start being able to dry cruise below 2T internal fuel

Thanks!

I checked that, really is on the limit as you say. I would not have thought, that the aircraft is capable of this (I don't think I ever flew that high with less than Mach 1,5  )

 

On the other hand, regarding the possible effects of a 10% L/D reduction, I did fly the engine out profile now with full A/A loadout + a droptank at full fuel, and still made it. I have even made a small S turn around 5000 feet to simulate the effect of a 30 degrees offset.

I'm not sure, what the combined drag penalty of the 2x Magic2 + 2x 530D + droptank is, but I would guess it is a lot. 

Please see the track attached.

I understand, that emergency procedures have tolerances built in, but this seems too much for me. Speed can be completely off of the optimum speed (demonstrated earlier), stores, droptanks can still be on, even with a turn.

M2000_engine_out_proc_err_FullAAload_droptank_1122.trk

[Galinette]

31 minutes ago, HWasp said:

Thanks!

I checked that, really is on the limit as you say. I would not have thought, that the aircraft is capable of this (I don't think I ever flew that high with less than Mach 1,5  )

 

On the other hand, regarding the possible effects of a 10% L/D reduction, I did fly the engine out profile now with full A/A loadout + a droptank at full fuel, and still made it. I have even made a small S turn around 5000 feet to simulate the effect of a 30 degrees offset.

I'm not sure, what the combined drag penalty of the 2x Magic2 + 2x 530D + droptank is, but I would guess it is a lot. 

Please see the track attached.

I understand, that emergency procedures have tolerances built in, but this seems too much for me. Speed can be completely off of the optimum speed (demonstrated earlier), stores, droptanks can still be on, even with a turn.

M2000_engine_out_proc_err_FullAAload_droptank_1122.trk 947.76 kB · 0 downloads

Did you disable slats?

[HWasp]

1 minute ago, Kercheiz said:

Did you disable slats?

Yes I did, but I have found something more interesting:

I just stumbled upon this combination : with 1 full center tank and 100% fuel, sustained rate at 340 kts is almost exactly 4,8G as per the video (that may or may not be relevant)

Also with the same configuration engine out procedure is fully safe (the previous loadout was really on the limit)

 

M2000_engine_out_proc_1droptank_1122.trk

[HWasp]

For this I have also disabled the slats, and made an S turn to simulate a 30 degree offset, so worst case scenario. I would consider this reasonably safe in this config

[myHelljumper]

From my dead engine tests with 100% fuel I have 39 nm until touching the ground following the procedure speed.

Using 200 kt I have 35 nm

Using 260 kt I have 42 nm.

Looks like it work as expected to me.

 

[Galinette]

Just opened one of your tracks (full AA) and you're still starting at 10000ft

[HWasp]

4 minutes ago, Kercheiz said:

Just opened one of your tracks (full AA) and you're still starting at 10000ft

"So the procedure goes as follows:

• 280 kt indicated should give you 14 nm for 10 000 ft. 280 is chosen because it's close to the best glide speed (~260 kt) and inside the engine relight domain. The slats should be forced in.
• Stabilize at 5000 ft to slow down to 230 kt minimum.
• Maintain 230 kt in final.

This procedure does not give fuel or configuration information but we can guess that in such emergency external stores would be jettisoned so the procedure must be possible with basically full fuel and no stores.

I'll record a track later."

This was the procedure given to me. I was testing this one.

[HWasp]

22 minutes ago, Kercheiz said:

Just opened one of your tracks (full AA) and you're still starting at 10000ft

Here is a 40nm one with a center droptank full + 100% fuel

had to do S-turns on short final, because ended up high

M2000_engine_out_proc_40nm__full_1droptank_1122.trk

[myHelljumper]

20 minutes ago, HWasp said:

"So the procedure goes as follows:

• 280 kt indicated should give you 14 nm for 10 000 ft. 280 is chosen because it's close to the best glide speed (~260 kt) and inside the engine relight domain. The slats should be forced in.
• Stabilize at 5000 ft to slow down to 230 kt minimum.
• Maintain 230 kt in final.

This procedure does not give fuel or configuration information but we can guess that in such emergency external stores would be jettisoned so the procedure must be possible with basically full fuel and no stores.

I'll record a track later."

This was the procedure given to me. I was testing this one.

Sorry I should've been more precise, the procedure scenario starts at 30 000ft and gives 41 nm.

Also the gear should be dropped at 5000 ft when the speed is 230 kt.

So the whole proc is :

• 280 kt indicated should give you 41 nm from 30 000 ft (~14 nm per 10 000 ft). 280 is chosen because it's close to the best glide speed (~260 kt) and inside the engine relight domain. The slats should be forced in.
• Stabilize at 5000 ft to slow down to 230 kt minimum then drop the gear.
• Maintain 230 kt in final.

Edited November 6, 2022 by myHelljumper

[HWasp]

13 minutes ago, myHelljumper said:

Sorry I should've been more precise, the procedure scenario starts at 30 000ft and gives 41 nm.

Also the gear should be dropped at 5000 ft when the speed is 230 kt.

So the whole proc is :

• 280 kt indicated should give you 41 nm from 30 000 ft (~14 nm per 10 000 ft). 280 is chosen because it's close to the best glide speed (~260 kt) and inside the engine relight domain. The slats should be forced in.
• Stabilize at 5000 ft to slow down to 230 kt minimum then drop the gear.
• Maintain 230 kt in final.

 

Dropping the gear at 5000 is a pretty damn big difference! That should have been important to note really

What is the reason for that? If I'm flying to survive an engine out like that, I will drop the gear only when landing is assured, otherwise it will just ruin my glide.

I would never drop the gear unless a technical reason makes it necessary.

btw if that is the case, why was it so important to fly from 40nm at 260 if you can just start the scenario at 10k 260 14nm? It's the gear, what will ultimately decide the difference...

[HWasp]

25 minutes ago, myHelljumper said:

 

Also the gear should be dropped at 5000 ft when the speed is 230 kt.

 

Ok, now it is your turn to demonstrate this with a track, because with the gear extended at 5000, you cannot reach the field from 10k test and is only barely survivable from 30k.

You are basically killing yourself with that 5000 feet gear down, I hope there is a strong technical case for that otherwise it is pretty strange.

[HWasp]

I'll have to amend that, it is not working from 30k 40nm with 280 as well.