Matching actual climb rates, turn rates in YSFlight

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Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Wed May 25, 2022 6:52 am

I have been using the YSFlight as an air combat game, but the turn rates and climb rates of aircraft seem to be different from the actual aircraft specifications.

The Mirage 2000, for example, had a very low climb rate, I found that the thrust settings were are 3t and 7t afterburner instead of more like 7t and 11t (Afterburner). When I changed the entries, I found I had better chances at winning in air combat against the F-16.

Has anyone info or experience with these values? I am in the process of testing the performance of several jet fighters and will probably launch these modded aircraft.

viewtopic.php?f=223&t=8182&p=92399&hili ... ate#p92399

A post from 2015:
Post by waspe414 » Sat Nov 21, 2015 2:51 am

REFVLAND 110kt #LANDING SPEED
REFAOALD 15deg #LANDING AOA
REFTHRLD 0.3 #LANDING THROTTLE SETTING

After maneuverability constants and thrust, those are the most significant variables for dogfighters, affecting how closely the velocity vector sticks to boresight, which affects turn rate and high-AOA drag.

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Wed May 25, 2022 7:26 am

For example

YSFlight

Thunderbirds F 16: 17 seconds to turn 360 degrees at 10,000 ft, 8g, 22 degrees/second
Also 13.3G sustained in afterburner after take-off at 200 knots. According to an actual pilot 'no fighter can sustain 9g' listed below. (f16.net)

Time to height: 20,000 in 1 minute.

Initial climb at sea level after take-off is 10,000 ft in 15 seconds which works out to 40,000 ft/min which seems more like the specifications.

Actual
Sustained turn rate: 14 degrees/ second
Not 9G, but right to that great plateau only the Viper has between 350-450 CAS at about 6-7 G where the Ps is zero, turn rate is about 14, and radius is 3-4K feet. You can feel it because it is light buffet as the LEFs are just barely programming
.

https://www.f-16.net/forum/viewtopic.php?t=26829

Initial Climb: 48,000 ft/min

Interesting:

https://contentzone.eurocontrol.int/air ... x?ICAO=F16&

https://www.f-16.net/forum/viewtopic.php?t=26829

https://www.f-16.net/forum/viewtopic.ph ... pe#p427421

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Thu May 26, 2022 11:03 am

F-16 turn rates

After some reading and deciphering of pilot code, I managed to find the following information (to be confirmed) from the F-16 flight envelope diagram at the F-16.net

https://www.f-16.net/forum/download/fil ... &mode=view

According to the diagram, the F-16 sustains 2g at 150 knots, which locks it into a certain turn rate and turning radius. The YSFlight model was able to pull 2g sustained at 120 knots or so, and this was obviously not correct. Even more incorrect was the sustained 13g turns at 400 knots or so - clearly outside the envelope.

The thunder.dat was edited, the landing speed moved to 130 kt, it actually now stalls at 100 and is just able to do 2g turns at 150kt, sustained, before the stall warning comes on. In combat against the Mirage 2000, it is easier to beat, which is a good thing. The Mirage 2000 flight envelope must be checked next.

Edits of .dat:

IDENTIFY "F-16C_THUNDERBIRDS" modded 26 5 22 ysg2000

WEIGLOAD 1.0t #WEIGHT OF PAYLOAD 5 > 1
..
REFVLAND 130kt #LANDING SPEED 90 > 130

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Re: Matching actual climb rates, turn rates in YSFlight

Post by waspe414 » Thu May 26, 2022 11:16 am

Have a look at the stock F-18C and F-16C_THUNDERBIRDS on the VioletWorld server (not VioletWorld2018). They're reasonably realistic in terms of sustained turn rate, and pitch/roll maneuverability. Hornet is more polished than Viper though. Turn performance at altitude isn't accurate because of YS's lack of transonic effects. I've not focussed on climb rate at all, but thrust to weight is correct, along with fuel consumption. I'm also about halfway through a realism A-10, and have an approximation of a realism MiG-21. End goal is all the stock aircraft

Realism F-16 compared to IRL F-16CJ data
Image

Realism F-16 vs realism F-18
Image

Stock F-16 performance
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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Thu May 26, 2022 12:13 pm

Hi

Those are some nice diagrams that will take time to review, however are you saying that the stock (YSFlight stock ) F-16 is capable of over 40 degrees per second 200 kt to 400kt? No wonder I found it hard to win!

The realism project seems like a good one, I would rather modify the aircraft myself and host the mod since I do not want copyright issues, and basically I am in control of all the aspects of the aircraft model.

How does Soji view the realism angle, that might be a good thing to include with the next upgrade.

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Thu May 26, 2022 12:28 pm

Mirage 2000

The Mirage 2000 flight envelope diagram shows that it can pull 2g at 160kt, something that seems to be confirmed by a recent view of a DCS combat video. That is 2g sustained. The YSFlight Mirage is a little higher than that, so some increase in landing speed might be in order, although the aircraft can fly as slowly as 100kt (Wikipedia)

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Thu May 26, 2022 4:38 pm

Testing Turn Rate Realism

I think I can find most of the flight envelope data online, so the task now is to do the testing. How do you test for realism?

Instantaneous turn rates
Instantaneous turn rates or maximum turn rate (without stalling) - the maximum turn rate regardless of loss of speed at any given speed and altitude. The g-loading will depend on the turn rate at this speed. Adjust the landing speed parameter until the aircraft stalls when turning at the highest g-loading that can be sustained at that speed.

Sustained Turn rates:
The turn rate at which there is no loss of speed. Find the g loading at that speed, altitude and turn rate, and maintain that g-loading without losing speed - using full afterburner in most cases.

Is this the correct testing procedure?

Above M 0.8 this does not seem to work for some reason possibly due to the limits of the flight model - in some cases 10+ g can be achieved - air-frame breakup?

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Re: Matching actual climb rates, turn rates in YSFlight

Post by waspe414 » Thu May 26, 2022 6:24 pm

Real aircraft have G-limiters built into the flight control laws. Additionally, a lot of fly by wire aircraft are G-driven, that is a certain pitch sets a desired G. YS is AoA-driven, where a certain pitch sets a specific AoA. This can lead to high-speed over-G

I do all my testing at sea-level because in YS the turn rate at altitude is reduced but the shape of the curve doesn't change. For sustained rate I record G loading and bank angle at a set airspeed (true or indicated doesn't matter because it's sea level), then run those through a spreadsheet to get the turn rate. Occasionally I sanity check that with a 90deg or 180deg timed turn (which I time using the replay feature). Set throttle and pitch trim as required to maintain the target airspeed

For instantaneous rate, I go to max speed, then do a full aft stick turn and pause as the airspeed bleeds off to record the same data (airspeed, G, bank angle), reducing throttle to zero once the rate of speed loss reduces

An important note: set fuel consumption to 0 for the tests otherwise your weight will change during testing, invalidating the dataset

The important variables to play with are CPITMANE, CPITSTAB, MXIPTAOA, MANESPD1, MANESPD2, REFVCRUS, REFTCRUS, REFVLAND, REFAOALD, and REFTHRLD. CLBYFLAP and CDBYFLAP are useful for tuning flap effects for additional turn rate or better landing performance. Wing area has no effect on flight performance

I don't have a specific process for setting the variables. Just start with something close-ish and iteratively modify the variables, check data, modify etc until a satisfactory rate curve is reached
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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Fri May 27, 2022 11:17 am

Mig -21

With the landing speed setting set to REFVLAND 200kt I obtain the results :

Maximum turn rates : 6.9 g at 390 kt, 3g at 290 kt no speed loss.

Thrust values seem correct since the Mig 21 averages 45,000 ft/min average to 10,000 ft

The lack of speed loss in turns, and the acceleration in 6 g turns is completely out of character, though I enjoy the stalling limit at 6g which happens very often. The F-16 flight model is also more realistic so it is not all that hopeless a fight.

What I have learned all along is completely wrong, about jet air combat parameters and the aircraft in question. I know realism packs have been around for ages, should have tried them out.

Any links to realism packs? Some of these links are not working: https://wordpress.ysfhq.com/resources/download-addons/

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Fri May 27, 2022 3:30 pm

Final settings for the Mig-21:

REFVLAND 200kt #LANDING SPEED

This give a maximum sustained 6g at 390 and 3.5g at 260, in a level turn. I was not keeping the airplane level - diving increases the ability to turn without stalling. Critical angle was also raised to 27 degrees and the airplane does not stall in turns, however turn rate cannot be increased beyond this rate even with full afterburner, I cannot raise the nose any further. Is there a setting for this?

This will have to do for now, but over 500 kt I can get 10+ g how do I limit this?

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Re: Matching actual climb rates, turn rates in YSFlight

Post by waspe414 » Fri May 27, 2022 6:28 pm

Reduce landing AoA and increase pitch maneuverability (or reduce pitch stability), or increase thrust to weight should increase turn rate
There's no way to effectively limit high speed turn G loading in the .dat, though 2ch has a program that does damage to aircraft above a set G limit if run on the server
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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Sat Jun 04, 2022 4:42 am

Changing landing speed corrects the problem to a huge extent.

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Re: Matching actual climb rates, turn rates in YSFlight

Post by YSG2000 » Mon Jul 04, 2022 10:41 am

A survey of landing speeds for several fighter aircraft results in the following: they cannot all be correct. I have checked some of the figures for the actual aircraft and they do vary somewhat. It remains to be seen what the effect
on turn rates is when the landing speed, which is about 1.2 times the stall speed, is correct.

I am creating set of repainted and corrected aircraft exclusively for my YSFlight air combat flights. I will only engage in combat with realistic aircraft against realistic aircraft.

In YSFlight, most of the aircraft have a landing speed of 110 knots, except for the F-16 and Hawk, which have it set at 90kt.
Attachments
YSFlightLandingSpeeds.png

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Re: Matching actual climb rates, turn rates in YSFlight

Post by decaff_42 » Mon Jul 04, 2022 2:22 pm

that is because the landing speed listed in YSF is just a point in the sky to define full flap and high AoA conditions to calculate lift/drag, not the actual speed the aircraft touches down at.
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