F-14B acceleration correct?

[bkthunder]

10 hours ago, Donut said:

So HB is saying don't trust the info bar...and they don't use it for testing; but, ED uses it and apparently it matches up to real life performance charts.

 

Maybe this explains why the Tomcat's performance is off...?

 

If the IAS displayed on the infobar matches the IAS on RL charts, then ED FMs are all wrong, because the infobar is not displaying IAS at all. As proven by different sources, it displays EAS, which is up to 100kts different than IAS. I would trust HB over ED here. 

And if you read the reddit post it says the only aircraft that gets it right is the Mirage (i.e. not an ED module). I don't think the F-14 was tested but it can be done and verified with the help of some online calculator and the Mach > IAS chart for supersonic speeds. 

 

edit: just did a quick test with the F-14. The IAS/CAS indicated on the gauge is pretty much correct for a given mach number. But here's something interesting: 

The TS (true speed) according to the infobar and F10 view is higher than it should be for that same Mach number. 

 

e.g. I tested at 20k feet and Mach 1.5, the TAS should be 920kt, but in the F-14 it's 933kts. 

The test was done in ISA conditions (15 degrees) and 0 wind, so TAS and GS are the same.

 

With the F-15, same conditions, TAS is 920kts, which is according to the chart on the reddit post, correct.

Edited May 28, 2021 by bkthunder

[draconus]

10 minutes ago, bkthunder said:

If the IAS displayed on the infobar matches the IAS on RL charts, then ED FMs are all wrong

ED answers:

Quote

This purely indication issue does NOT affect DCS FM under any circumstances.

https://old.reddit.com/r/hoggit/comments/njx988/f18_f16_mirage_f15_and_others_wrong_airspeed/

You can find the pdf link there to the quoted doc.

[Bremspropeller]

Indicated Mach number isn't always true Mach number.

 

 

Now for something completely different:

 

What's the max Mach people have achieved in the cat?

I've had an A-model at Mach 2.25 yesterday (clean). Has anybody seen Mach 2.3+ yet?

[Spurts]

2 hours ago, Bremspropeller said:

Indicated Mach number isn't always true Mach number.

 

 

Now for something completely different:

 

What's the max Mach people have achieved in the cat?

I've had an A-model at Mach 2.25 yesterday (clean). Has anybody seen Mach 2.3+ yet?

When the A first came out I hit 3.0 at 70,000ft, then they fixed the runaway thrust.

[Victory205]

I did some investigation last night, including timed runs, and am in the process of reducing the data. The problem includes interfacing the cockpit indication with the performance charts. A pilot flys the instrument that are available in the air, not an info bar. The idea that an info bar is the holy grail was never valid. A pilot uses the instruments in the cockpit to maximize performance in combat, therefore, the cockpit information should be correct and valid with respect to the EM charts.

 

One must be mindful of the references on those charts. Most provide IMN or IAS (a few don’t). There is also instrument position error causes by Mach effects. I am not sure that any other modules model the large transonic static errors, or how DCS handles that in their calculations, and whether other aircraft performance charts incorporated those into their presentations. If you know, which will require studying the instructions to the chart included in the performance manuals.

 

There is a lot more complexity behind the scenes than you are able to see right now, especially with Mach. It would be nice if DCS followed through, and standardized and calibrated all data, including transonic effects, once and for all. It isn’t easy to do, but that would provide a better basis for tailoring aircraft vs aircraft performance.

[Spurts]

40 minutes ago, Victory205 said:

. I am not sure that any other modules model the large transonic static errors

Watching the gauges swing as I go through the mach is always a treat.

[Hummingbird]

8 hours ago, draconus said:

Here:

 

Well, the report is about the incorrect IAS, not TAS/TMN.

 

Yes that's my point, I see no reason for the infobar TAS/TMN to be incorrect as it merely records the actual movement of the aircraft in the simulation, hence it should be THE most accurate measurement available and what is used for calibrating aircraft performance vs official charts. If some devs aren't doing this, then that could explain some of the issues we're seeing.

 

We need to keep in mind that the performance charts are corrected for true mach number, thus if the devs are using IAS or IMN to calibrate performance then the end result is incorrect performance. In order to get correct performance you NEED to calibrate using TAS/TMN, and only the infobar provides this.

 

 

Edited May 28, 2021 by Hummingbird

[Hummingbird]

8 hours ago, bkthunder said:

edit: just did a quick test with the F-14. The IAS/CAS indicated on the gauge is pretty much correct for a given mach number. But here's something interesting: 

The TS (true speed) according to the infobar and F10 view is higher than it should be for that same Mach number.

 

 

Keep in mind there's a difference between IMN and TMN, and all the performance charts are for TMN, which only the infobar shows.

[fat creason]

TAS and TMN on the infobar are likely to be valid, it would be pretty hard to screw that up (although nothing would surprise me at this point). The problem I'm talking about is the IAS labeled value in the infobar and HUD/instruments of some modules, it's actually EAS or something else that's not IAS. F10 view "TAS" might also actually be groundspeed. Like @Victory205said above, the performance charts are against Mach and IAS since that is what's available to the pilot from the cockpit. I'm going to make sure the IAS from the cockpit is correct, someone smarter than I (@Super Grover perhaps?) did the CADC so it's probably good . If you're checking EM charts or something you can probably trust the infobar Mach number.

Edited May 28, 2021 by fat creason

[Victory205]

1 hour ago, Hummingbird said:

 

 

Keep in mind there's a difference between IMN and TMN, and all the performance charts are for TMN, which only the infobar shows.

 

Can you share how to make the info bar display True Mach number?

[captain_dalan]

23 hours ago, Donut said:

So HB is saying don't trust the info bar...and they don't use it for testing; but, ED uses it and apparently it matches up to real life performance charts.

 

Maybe this explains why the Tomcat's performance is off...?

Nope, the performance is off even down low, where the is practically no difference between the speeds.

14 hours ago, draconus said:

Here:

 

Well, the report is about the incorrect IAS, not TAS/TMN.

Ah there it is, we have it from the devs. It's the TMN that we'll have to go with for most charts then!

[Hummingbird]

4 hours ago, Victory205 said:

Can you share how to make the info bar display True Mach number?

 

 

It displays TAS, which is then easily converted to TMN when you know the altitude, and vice versa, for checks vs the charts. 

 

As all tests are done in zero wind and std. atmosphere, as on the charts, TAS is all we need.

Edited May 28, 2021 by Hummingbird

[Victory205]

6 hours ago, Hummingbird said:

It displays TAS, which is then easily converted to TMN when you know the altitude, and vice versa, for checks vs the charts. 

 

As all tests are done in zero wind and std. atmosphere, as on the charts, TAS is all we need.

 

 

So you referenced, over and over, your “precise” testing using True Mach off of the info bar, and it doesn’t exist? 

 

Man.

[unknown]

4 hours ago, Victory205 said:

 

 

So you referenced, over and over, your “precise” testing using True Mach off of the info bar, and it doesn’t exist? 

 

Man.

Why is this post edited but has not the "Edited x hours ago by xyz" tag at the bottom of the post? Or was the original post deleted? That sounded quite different a couple hours ago.

 

18 hours ago, Victory205 said:

The problem includes interfacing the cockpit indication with the performance charts. A pilot flys the instrument that are available in the air, not an info bar. The idea that an info bar is the holy grail was never valid.

You can toggle on/off the info bar in the cockpit view also. So if you have your FM "calibrated to the reference source" you can cross check the speeds from the Info bar to your instruments if they show correct values for the pilot to use for optimal performance.

[Snappy]

On 5/28/2021 at 11:00 AM, draconus said:

ED answers:

https://old.reddit.com/r/hoggit/comments/njx988/f18_f16_mirage_f15_and_others_wrong_airspeed/

You can find the pdf link there to the quoted doc.

„This purely indication issue does NOT affect DCS FM under any circumstances.“

 

while this statement from ED might not necessarily be false in itself, I find it’s oversimplifying things a bit.

The FMs themselves may still be unaffected, but if your cockpit indications are wrong (yes I know they’re almost never totally accurate  anyway)by an increasing margin in some aircraft , then you actually are in a different part of the performance envelope than you think you are based on your instruments.(mach indications are hopefullly semi correct at least).

So your aircraft would not be giving you the performance you would expect.

 

Anyway the whole discussion is very interesting and educational to me, but it hasn‘t exactly increased my confidence in the degree of simulation realism provided by ED,given the number of incorrect basic speed indications either in cockpit, HUD ,F10map or infobar. If this basic core stuff is buggy I don’t wanna know what else is.

 

food for thought.. 

 

But I‘m thankful that Heatblur and Victory are taking a different, more meticulous approach.

 

 

kind regards, Snappy 

 

 

 

Edited May 29, 2021 by Snappy

[Hummingbird]

18 hours ago, Victory205 said:

 

 

So you referenced, over and over, your “precise” testing using True Mach off of the info bar, and it doesn’t exist? 

 

Man.

 

In std. atmosphere (i.e. zero wind, 15C @ SL), if I know TAS and altitude, then I know TMN, and vice versa if I know TMN & altitude, I know TAS. There's really nothing more to it. 

 

Hence to make the checks: You decide on an altitude and the speeds you want to check at, and since speed on the F-14's performance charts is listed in TMN, you then simply convert that into TAS and you know precisely what speeds to aim for on the infobar during the test flight. It's that simple, and exactly how I tested the F-14 & F-15. Other aircraft performance charts show performance vs KTAS, which allows you to skip a step.

 

In short, what's the problem?

 

The main point here is that only the infobar shows TAS/TMN, which is a recording of the aircraft's actual movement within the simulation, aircraft instrumentation will not. As such the infobar TAS reading is what performance needs to be calibrated in accordance with, as otherwise you will end up with incorrect performance.

Edited May 30, 2021 by Hummingbird

[Hummingbird]

14 hours ago, unknown said:

Why is this post edited but has not the "Edited x hours ago by xyz" tag at the bottom of the post? Or was the original post deleted? That sounded quite different a couple hours ago.

 

If you have admin/moderator privileges, then edits don't show.

[captain_dalan]

 

 

 

Wanna do something right, do it yourself. I don't know about any other planes, but if you insist i'll test those as well, but for the F-14, that info bar seams quote on the money for me......

Edited May 30, 2021 by captain_dalan

[bkthunder]

5 hours ago, captain_dalan said:

 

 

 

Wanna do something right, do it yourself. I don't know about any other planes, but if you insist i'll test those as well, but for the F-14, that info bar seams quote on the money for me......

 

 Please read this from my previous post and try to test it: 

 

Quote

edit: just did a quick test with the F-14. The IAS/CAS indicated on the gauge is pretty much correct for a given mach number. But here's something interesting: 

The TS (true speed) according to the infobar and F10 view is higher than it should be for that same Mach number. 

 

e.g. I tested at 20k feet and Mach 1.5, the TAS should be 920kt, but in the F-14 it's 933kts. 

The test was done in ISA conditions (15 degrees) and 0 wind, so TAS and GS are the same.

 

With the F-15, same conditions, TAS is 920kts, which is according to the chart on the reddit post, correct.

 

[Donut]

8 hours ago, captain_dalan said:

 

 

 

Wanna do something right, do it yourself. I don't know about any other planes, but if you insist i'll test those as well, but for the F-14, that info bar seams quote on the money for me......

 

Thank you for doing this.

 

If what Victory205 and fat creason have said is true about how they test the FM...(HB only uses the instruments in the cockpit (which shows CAS) to test and verify against performance charts and not the info bar)...this clearly shows that they are incorrect and the Tomcat's performance is off...maybe way off.

 

 

[captain_dalan]

5 hours ago, bkthunder said:

 Please read this from my previous post and try to test it: 

 

 

Will do. Will also run with the other planes, especially those that have both a dial and HUD airspeed indicator. Just don't know when can i get to it. RL has been extremely busy (and hectic) as of late

[captain_dalan]

2 hours ago, Donut said:

Thank you for doing this.

 

If what Victory205 and fat creason have said is true about how they test the FM...(HB only uses the instruments in the cockpit (which shows CAS) to test and verify against performance charts and not the info bar)...this clearly shows that they are incorrect and the Tomcat's performance is off...maybe way off.

 

 

I don't believe that the performance is off because of that. At least not the difference we've been investigating. Yes, the manuals seam to refer to IAS which correlates to EAS rather then CAS when compared with the mach number, but the difference is tiny compared to the performance delta, especially down low, say 5000ft and 10000ft. Besides, some of the charts (the ones with the 3, 5 and 6.5 g intersections of the altitude, mach and Ps curves, are given in mach numbers only, and i always used those for the low level tests. As for higher up, i can't tell. I never tested that, nor did i test performance above mach 0.9, i was mostly interested in the "dogfighting" corner of the envelope.

[Skysurfer]

Can we all like wait until the FM changes are in before we continue this discussion? This just seems like one big circlejerk at this point and people arguing about what speed is what.

[Donut]

2 hours ago, Skysurfer said:

Can we all like wait until the FM changes are in before we continue this discussion? This just seems like one big circlejerk at this point and people arguing about what speed is what.

Good advice.  HB has acknowledged that the FM is off and they are working on it.  I guess we will wait and see what it does to acceleration.
 

I never intended my OP question to turn into all of this...it was a yes or no question, which of course remains unanswered.

[Hummingbird]

21 minutes ago, Donut said:

Good advice.  HB has acknowledged that the FM is off and they are working on it.  I guess we will wait and see what it does to acceleration.
 

I never intended my OP question to turn into all of this...it was a yes or no question, which of course remains unanswered.

 

Still it seems it was important we had this debate, as it appears HB weren't using the infobar's TAS reading to calibrate performance, which is needed as the infobar reading shows precisely how fast the aircraft is moving within the simulation. So they will probably/hopefully use this moving forward.

 

That said, if we look at Cpt. Dalan's picture the F-14's mach meter interestingly seems to be corresponding exactly with the infobar's TAS reading and thus seems to show TMN. Not sure if the F-14's mach meter was capable of this IRL, usually mach meters show IMN which just like IAS has some error.

 

Edited May 30, 2021 by Hummingbird