correct as-is Does Hornet have too much lift

[Swift.]

So for a while now I've been thinking about all the FM artefacts we are seeing in DCS

1. Range Cruise AOA is too low (3.2 vs 4.2 IRL) 
2. Low speed fuel burn is too high
3. Bleed during turns is too low
4. Sustained turn rate is too high (suspected)

It's occurred to me that all of the above can be explained by hornet having too much lift, or more specifically a Lift/Drag ratio that's too high.

1. If the airframe produces too much lift, then it wont need to meet the same AOA to fly level at a given speed, so we will see lower AOA values for cruise flight.
2. If the fuel burn was calibrated for range cruise, it would have to be increased to account for this lower L/D. This would make the burn match the specific range charts for maximum range flight, but when you fly slower, the fuel burn becomes artificially increased above where it should, which is why the fuel burn is much higher than the specific range charts indicate at low speed.
3. Too much L/D means less AOA required to make the G specified, so less AOA during turns, less AOA means less bleed.
4. Same as point 3, less bleed means more thrust overhead.

Hopefully ED will fix hornets FM at some point in the immediate, perhaps all thats needed is a simple L/D adjustment, perhaps more is needed, idk

[BIGNEWY]

Please attach your track replays and any evidence you have. 

thanks

[Swift.]

53 minutes ago, Gypsy 1-1 said:

It may also be that the Cdi (induced drag) and AOA relation are off - in essence, too little induced drag as well as maybe too little total drag overall. This would exlain the bleed rate at higher speeds and lower AOA's. Without having any performance charts or L/D diagrams to compare it is really hard to verify this other than listening to some SME feedback over the years.

Thats possible. Some numbers are hard verifiable facts, for example the cruise AOA (4.2/5.6) is a number from natops. And the performance charts have fuel burn on the specific range charts, I just hadn't made reports yet because I figured ED would have those sources for their FM rework. Perhaps I shouldn't assume though.

The bleed during turns is a harder one to pin down, all you have is vague anecdotes, which is a challenging metric.

[Dragon1-1]

If cruise AoA is off, then either lift or drag is off. This may be indicative of a deeper bug (like the recent issue with pylon drag on the Viper), generally in FM work you can't change something like this without knock-on effects through the envelope, so let's focus on the number we know is wrong, and see what happens after that is corrected.

[RentedAndDented]

Hmm I would have to double check but I could swear my cruise AOA is closer to 4 than 3 when I follow the FPAS page? Am I missing something there?

And - the sustained turn rate matches the GAO document so I don't know what else they can do. I also saw the -400 turn charts and I don't think it is too far off from where a -402 engined Hornet might end up (about where the GAO doc is) but I wouldn't genuinely know either.

[Swift.]

1 hour ago, RentedAndDented said:

Hmm I would have to double check but I could swear my cruise AOA is closer to 4 than 3 when I follow the FPAS page? Am I missing something there?

And - the sustained turn rate matches the GAO document so I don't know what else they can do. I also saw the -400 turn charts and I don't think it is too far off from where a -402 engined Hornet might end up (about where the GAO doc is) but I wouldn't genuinely know either.

Err, last time I checked the perf charts natops doesn't have EM diagrams.

As for the AOA you might have seen a number close to 4 when very heavy and draggy, but it should apply more universally than that. I'll be devising a series of demonstrations for the errors in the FM as this AOA discrepancy is present in other regimes. For example M0.6 4000ft 30k, expected AOA is 2.5ish, DCS shows 1.7.

Combine that with the fuel burn issues very clearly highlighted in the specific range charts. There is a still a *lot* of work left on the FM.

Edited May 4, 2022 by Swift.

[RentedAndDented]

There is a supplement out there for the -400 I found some time back. The -402 I have never seen. I am going off memory of years ago mind you, fully admitted. But that's what I recall.

[Swift.]

4 hours ago, RentedAndDented said:

There is a supplement out there for the -400 I found some time back. The -402 I have never seen. I am going off memory of years ago mind you, fully admitted. But that's what I recall.

Yeah when I say performance charts I refer to the NFM-200 and NFM-210 supplements, both of which don't have EM charts. They do have basic turn rate conversions but those dont really do the job.

[BIGNEWY]

4 hours ago, Swift. said:

There is a still a *lot* of work left on the FM.

You say something is wrong but you do not bring any evidence of it, claiming there is a lot of work to be done on the FM is nonsense 

[Swift.]

5 hours ago, BIGNEWY said:

You say something is wrong but you do not bring any evidence of it, claiming there is a lot of work to be done on the FM is nonsense 

Good afternoon Bignewy,

Please find attached a selection of outstanding FM bugs, as verified on 04MAY2022.
 

 

[BIGNEWY]

The AOA issues that are already reported are known. 

your new issues that you have only just posted will need to be investigated and confirmed if they are an issue or not. 

you are trying to make it sound like there is a massive amount of work to do on the flight model, and it is not true. 

thanks

[Swift.]

10 minutes ago, BIGNEWY said:

The AOA issues that are already reported are known. 

your new issues that you have only just posted will need to be investigated and confirmed if they are an issue or not. 

you are trying to make it sound like there is a massive amount of work to do on the flight model, and it is not true. 

thanks

My apologies then, I guess that shows my inexperience with coding Flight Models. Perhaps I should have said there are widespread issues with the FM, the level of work required to fix them is unknown to me.

In any case, thank you for processing those other bugs.

[Wing]

1 hour ago, Swift. said:

Good afternoon Bignewy,

Please find attached a selection of outstanding FM bugs, as verified on 04MAY2022.
 

 

After the requested evidence was posted as shown above, why is this thread still mislabeled "correct-as-is"?