Turn indicator may not indicate standard rate turns correctly

[Bestandskraft]

I cannot categorically prove that the following is a bug, I would simply ask the dev team to check whether the turn indicator is working as intended.

 

According to NATOPS, "[a] needle-width deflection of [the Turn-and-Slip indicator's] pointer will initiate a 360° turn in 4 minutes." Tests conducted by me have confirmed that this is correctly simulated. A needle-width deflection thus indicates a half-standard rate turn.

 

However, a two needle-width deflection (put the white on the white) which I would expect indicates a standard rate turn in fact does not do so in the game. My tests have shown that a 180° turn with said deflection takes approximately 50 seconds instead of 60.

 

Some basic aerodynamic math confirms the discrepancy: For example, at 289 KTAS, a 3° per second turn rate should be achieved at a bank angle of 38°. In the game, at 289 KTAS, a two needle-width deflection coincides with a bank angle of approximately 44° on the VDI.

 

If the indicator is modelled correctly as is, I request information about how (or if) RL F-14 pilots were able to fly standard rate turns precisely.

 

Incidentally, I can confirm the findings reported in this post concerning a significant difference between the bank angle indicated on the VDI and the Standby Attitude Indicator.

Edited August 18, 2021 by Bestandskraft

[Victory205]

We didn’t fly standard rate turns, only half standard rate, which is common in jets since once above 205 KTAS a SRT requires over 30º AOB. The turn needle is cross referenced, but primary the correct bank angle is held using the VDI. Experience is such that the pilot becomes familiar with the required AOB in typical holding.

 

Timing to make the assigned push in the marshal stack was about the only place timing in turns was a player, Otherwise, the max angle of bank under instrument flight procedures was limited to 30º and due to the fact that typical KTAS would exceed that for a standard rate, the pilot accepts whatever the turn rate resulted. Again, typical in jets. In IMC/IFR, the max AOB is 30º, or 25º if a flight director is available.

 

Only thing I can offer is to ensure that you are referencing KTAS and not KIAS. Sounds like you are up to speed on that, however.

Edited August 18, 2021 by Victory205

[Bestandskraft]

Awesome, thanks. Just for my peace of mind: The white markings at the outer edges of the turn scale then do not indicate any specific turn rate, but exist merely to aid the pilot in setting the turn needle between the center and outer markings to establish a half-standard rate turn?

Edited August 19, 2021 by Bestandskraft

[Callsign JoNay]

I've been practicing CASE-3 marshals, and wanted to bump this thread. I know Victory said that they didn't do standard turn rates, (only half standard), but that doesn't really answer the question about whether or not the turn indicator is working as intended by Heatblur.

 

The F-14's turn indicator when performing a standard turn, 180-deg/minute.

The F-18's turn indicator when performing a standard turn, 180-deg/minute.

Similar AOB, around 40-deg for both, but the turn indicator looks very different. The F-18 shows two needle deflections, the F-14 only shows about 1.5. Heatblur never marked the topic as "no bug", so I'm wondering if someone can verify.

[Spurts]

Whats the speed on the F-14?  same bank angle means same G, so turn rate is dependant on airspeed.

[Callsign JoNay]

10 minutes ago, Spurts said:

Whats the speed on the F-14?  same bank angle means same G, so turn rate is dependant on airspeed.

Same as the 18. Around 300 GS in low winds, so around 300 TAS +/- 20?

Are you seeing a two needle deflection in the Tomcat when you make a standard turn?

[IronMike]

1 hour ago, Callsign JoNay said:

Same as the 18. Around 300 GS in low winds, so around 300 TAS +/- 20?

Are you seeing a two needle deflection in the Tomcat when you make a standard turn?

One needle deflecting represents a 360 in 4 minutes. You're indicating about 2 needle deflections, and you say it is 180°/min, or 360 in 2 minutes. Aka, no bug indeed. 

 

[Callsign JoNay]

2 hours ago, IronMike said:

One needle deflecting represents a 360 in 4 minutes. You're indicating about 2 needle deflections, and you say it is 180°/min, or 360 in 2 minutes. Aka, no bug indeed. 

 

Really?...Hmmmm my VDI picture looks like it's showing 1.5 needle deflections to my eyes.

So if my VDI picture is showing two needle deflections, how many needle deflections is the F-18 ADI showing?

Edited August 3, 2022 by Callsign JoNay

[Spurts]

8 hours ago, Callsign JoNay said:

Same as the 18. Around 300 GS in low winds, so around 300 TAS +/- 20?

Are you seeing a two needle deflection in the Tomcat when you make a standard turn?

Am I misreading the Horent indicator?  It looks like it's doing 240, not 300+-

[Callsign JoNay]

4 hours ago, Spurts said:

Am I misreading the Horent indicator?  It looks like it's doing 240, not 300+-

240 CAS.

[Spurts]

Oh duh.  Thanks @Callsign JoNay

[IronMike]

14 hours ago, Callsign JoNay said:

Really?...Hmmmm my VDI picture looks like it's showing 1.5 needle deflections to my eyes.

So if my VDI picture is showing two needle deflections, how many needle deflections is the F-18 ADI showing?

 

Matters little, as two different instruments, with completely different symbology. From the manual I gather 2 needle deflections from center, so twice the width of the needle from center, as in centerline, not the edge of the white center marker. I may be wrong though or interpreting it wrongly, so I will double check.

nullnull

Edited August 3, 2022 by IronMike

[kablamoman]

31 minutes ago, IronMike said:

may be wrong though or interpreting it wrongly, so I will double check.

I think you may be interpreting it wrong.

If the instrument is centered, and there is a "needle-width deflection" it would be squarely in the black space between the two white marks. 2 such deflections would put it in line with the outboard white marks.

What's more, every plane I've ever flown with a turn & slip/turn & bank/turn coordinator has marks denoting standard rate turns (3 degrees per second). 

 

 

Edit: In the rough diagram you made above, your reference point would have been the very center of the needle if flying straight and level, but you change the refence to be the outside of the needle once deflected. A correct translation of one "needle-width deflection" from center would give you the needles new center, and not its edge as you've depicted  -- so it seems to me it should be right in the middle of the black space -- if that makes sense.

Edited August 3, 2022 by kablamoman

[Naquaii]

According to the NATOPS one needle-width deflection represents a 360 degree turn in 4 minutes. Some fast jets use this instead of the standard 2 minutes even though a standard turn is always 2 minutes.

Edited August 3, 2022 by Naquaii

[kablamoman]

Quote

Matters little, as two different instruments, with completely different symbology. From the manual I gather 2 needle deflections from center, so twice the width of the needle from center, as in centerline, not the edge of the white center marker. I may be wrong though or interpreting it wrongly, so I will double check.

Here's a chart to show where I think you're going wrong. You can measure it from center like you're doing, but it gives you the new center of the needle -- not the edge.

Hopefully this makes sense:

Edited August 3, 2022 by kablamoman

[Naquaii]

2 minutes ago, kablamoman said:

Here's a chart to show where I think you're going wrong. You can measure it from center like you're doing, but it gives you the new center of the needle -- not the edge.

 

Hopefully this makes sense:

 

null

No argument from me there, if you measure from center you should measure to center.

If this is no longer correct in DCS that's a bug but it used to work correctly.

Edited August 3, 2022 by Naquaii

[kablamoman]

1 minute ago, Naquaii said:

No argument from me there, if you measure from center you should measure to center.

Whoops, thought you were mike -- icon tricked me! 

[Callsign JoNay]

Ok, I'm glad I'm not crazy.

It just makes sense that the home plate symbols on the left and right of the turn indicator would mark something important. It doesn't make sense to me that a standard turn would require the turn needle to be lined up half way over the home plates.

[IronMike]

I double checked, and I was wrong, it is indeed 1.5, not 2.

@Callsign JoNay please try this for me, set it to 2 (that is on the outer marker) at 230 kts, and let me know what you get please. thank you!

11 minutes ago, kablamoman said:

Here's a chart to show where I think you're going wrong. You can measure it from center like you're doing, but it gives you the new center of the needle -- not the edge.

 

Hopefully this makes sense:

 

null

Thank you, you are right, I interpreted it wrongly.

[Callsign JoNay]

33 minutes ago, IronMike said:

I double checked, and I was wrong, it is indeed 1.5, not 2.

@Callsign JoNay please try this for me, set it to 2 (that is on the outer marker) at 230 kts, and let me know what you get please. thank you!

Thank you, you are right, I interpreted it wrongly.

With two needle deflections at 230 KIAS I complete a 360-deg turn in about 80-85 seconds.

 

[IronMike]

2 hours ago, Callsign JoNay said:

With two needle deflections at 230 KIAS I complete a 360-deg turn in about 80-85 seconds.

 

Excellent, thank you very much! Then I would say you were correct in assuming it is a bug. We will look into it.

Thank you for all your input.