Su27 Wing Thing

[apocom]

I mean, are we to say that a Russian pilot sitting in a Su-27 simulator at Maryy needs something extra that's not there in the actual jet not to overstress or destroy his virtual aircraft when he's flying around heavy, or does he work through the problem by developing good habits that will actually translate over?

 

You don't need to fly around heavy, you can fly around completly empty and destroy the aircraft without any problems.

 

Also you can only develop good habits with some kind of feedback. Just imagine for a moment you would insta G-Loc without the tunnel effect. It would be basicly impossible to develop a good habit other than watching your gauges.

 

Why would it be such a problem to develop some kind of feedback in that sim. Would that be so unrealistic? Something like a buzzing sound when you are half a G away from total destruction.

[DarkFire]

You don't need to fly around heavy, you can fly around completly empty and destroy the aircraft without any problems.

 

Respectfully, it really isn't that easy. Yes one can trundle around at 1.2M at max fuel weight and do an instant, max-G turn which will break the wings, but it's a deliberate action at that point. Turns up to 7G at max weight, at cruise speed will not break the wings.

 

More generally, modern Su-27 variants apparently have a Nadia that takes in to account the all-up weight of the aircraft so the pilot will get accurate audion G limit warnings. The fact that the older Su-27s didn't have this probably comes down (as so many things do with the Su-27) to the pilot having the experience to be able to feel the current G level and therefore knowing what G level not to exceed.

 

Of course, we don't get that level of feedback in a game, which makes things more difficult. I'd argue that this is one of the very, very few areas where the game ought to make a realism concession and have an auto-calibrating Nadia even if actual early VVS / PVO Su-27s didn't.

[lunaticfringe]

You don't need to fly around heavy, you can fly around completly empty and destroy the aircraft without any problems.

 

As well you should; the aircraft has structural limits, and the FBW is not designed to limit them. This, however, is not the nature of the original discussion given the track/acmi file involved. The aircraft was fundamentally overweight for the limitation set in the -1. Structural limitation was substantially exceeded, and the aircraft fell apart. Why would we expect it to do anything less?

 

Also you can only develop good habits with some kind of feedback. Just imagine for a moment you would insta G-Loc without the tunnel effect. It would be basicly impossible to develop a good habit other than watching your gauges.

 

There's this thing called the "horizon". Really spectacular feedback tool for developing habits regarding rate of turn as developed by G at speed. And glancing back to monitor speed loss is a fundamental aspect of flying an aircraft in combat. It doesn't require fixating on the gauge; a momentary glance to check for loss, gain, or constant rate tells you all you need to know, and let's you get back to the task at hand.

 

Hell, DCS is really nice about it, granting you the ability to dedicate a view key to do exactly that, with an instantaneous return to your previous viewpoint upon release, while the actual pilot has to turn around. And yet, when circumstances demand it, they manage it.

 

Why would it be such a problem to develop some kind of feedback in that sim. Would that be so unrealistic? Something like a buzzing sound when you are half a G away from total destruction.

 

It would be unrealistic because the actual aircraft doesn't have it.

 

What this is really boiling down to is that it is being expected that the Su-27 be permitted to flown like an F-16 (with an FBW limiter) or an F-15 (with OWS warning), rather than a Su-27.

 

Really makes me excited to see the complaints when the F-14A gets here with the TF30s high AoA setting change limitations. :lol:

[Frostie]

It would be unrealistic because the actual aircraft doesn't have it.

 

 

And you know this because of?

It has been mentioned of the actual Flanker having limited stick movement and stick vibrations of 8Hz.

 

Lets get back to ED recreating a simulator based on real life and how rl influences can be translated into DCS instead of the thought of ED simulating a simulator.

[lunaticfringe]

And neither of those function as a literal G inhibitor, an audible warning, or a visual cue- unless of course you're staring at the stick.

 

So yes, lets get back to ED recreating a simulator based on real life and dealing with the operational ramifications of such rather than piling up a bunch of add ons and excuses.

[GGTharos]

Yes, but it's for AoA - and for this you have the W key to relax the AoA constraints.

 

Nadia is tuned for a 21 ton jet, IIRC.

 

And you know this because of?

It has been mentioned of the actual Flanker having limited stick movement and stick vibrations of 8Hz.

[probad]

what is muscle memory for 500

[apocom]

And neither of those function as a literal G inhibitor, an audible warning, or a visual cue- unless of course you're staring at the stick.

 

So yes, lets get back to ED recreating a simulator based on real life and dealing with the operational ramifications of such rather than piling up a bunch of add ons and excuses.

 

But sometimes we have artifical improvements to make the game more accessible or to overcome limitations because it's a simulation. Like the cockpit zoom.

[Pocket Sized]

what is muscle memory for 500

 

+1

[DarkFire]

Yes, but it's for AoA - and for this you have the W key to relax the AoA constraints.

 

Nadia is tuned for a 21 ton jet, IIRC.

 

21,400 Kg according to the manual, but yes.

 

By "pure coincidence", an Su-27 with 30% fuel, 2 x R-27ER, 2 x R-73, full expendables and a full gunpad weighs in at 21,414 Kg. Or, an Su-27 with 4 x R-73, full expendables and full gunpad with 56% fuel weighs in at 23,396 Kg.

 

Looks like the early PVO Su-27s had their Nadia tuned for some sort of short range interception or airfield defence mission in mind.

[lunaticfringe]

But sometimes we have artifical improvements to make the game more accessible or to overcome limitations because it's a simulation. Like the cockpit zoom.

 

There is a substantial difference between accessibility, such as a zoom function which factors to all players based on apparent resolution between the human eye and a computer monitor, or the inclusion of aids for color blindness or deafness, versus the creation of an analogue to a pilot assist function that is unavailable on the type in question.

 

It's interesting to note that, as I've mentioned, there already exists a method to do exactly what a pilot does to function as an assist here. Subsequently, I'm left to believe this isn't an argument about accessibility, but one of difficulty, because it's hard to put aside old habits or deal with a decrease in relative ease of employment.

 

But cheer up- max performing a Flanker is difficult in real life, too.

[apocom]

There is a substantial difference between accessibility, such as a zoom function which factors to all players based on apparent resolution between the human eye and a computer monitor, or the inclusion of aids for color blindness or deafness, versus the creation of an analogue to a pilot assist function that is unavailable on the type in question.

 

It's interesting to note that, as I've mentioned, there already exists a method to do exactly what a pilot does to function as an assist here. Subsequently, I'm left to believe this isn't an argument about accessibility, but one of difficulty, because it's hard to put aside old habits or deal with a decrease in relative ease of employment.

 

But cheer up- max performing a Flanker is difficult in real life, too.

 

You took the wrong side of the argument, I've meant more the simulation limitations, like that our monitors have a worse resolution than our eye or we just can't feel the G.

 

I've put already a few hundred hours in the Flanker after the patch and I think I will never be able to fly it at it's structural limit. I'm just wondering if this is easier for a real pilot just because he feels the aircraft.

 

But of course, we adept and deal with it.

Oddly enough that the broken wings patch increased my enjoyment and frustration in flying the Flanker. :thumbup:

[DarkFire]

I've put already a few hundred hours in the Flanker after the patch and I think I will never be able to fly it at it's structural limit.

 

Oddly enough that the broken wings patch increased my enjoyment and frustration in flying the Flanker. :thumbup:

 

You will be able to. Gradually you get used to listening to the air turbulence sound at a given combination of G & air speed.

 

I agree completely about the broken wings: makes it much more interesting to fly. Harder to learn but more rewarding. Having flown and loved the current PFM Su-27, going back to the SFM Su-33 feels neutered and totally on-rails. I'd never go back now :)

[jackmckay]

 

AoA spike(purple) can't be that high compared to pitch(green). Plane wasn't on that turn rate ever(!) during flight. There's been an ERROR in flight dynamics calculation process!

[jackmckay]

No, it's not.

 

God's G is 1G. The most God's G ever effects your aircraft is 1G. Doesn't matter how much you pull, how little you pull, where your nose is pointed, where your center of gravity is- it is *always* 1G.

 

What destroys your aircraft is radial acceleration- how much you put on the stick.

 

When you turn with gravity, the radial rate of your turn is increased by up to 1G. But purely the *rate of turn*. The actual load on the aircraft is the G you invoke with the stick.

 

Ergo, if you are inverted- with your lift vector pointed straight down, and you pull a 5G 90 degree turn to nose straight down, your nose will rate as though accelerated by 6G as it is assisted by gravity, but the actual load on the airframe remains 5G.

 

Conversely, in a 5G 90 degree pull up from level flight, your nose will rate as though accelerated by 4G as it is degraded by gravity, but the actual load on the airframe remains 5G.

 

Every manual on air combat for the last 70 years has shown the energy egg. If you don't believe the laws of physics, there is nothing else anyone can tell you that will make a difference.

 

So conclusion would be that: if your plane is fixed on max G limit on specific configuration then -if going up the gravity you would have lover possible turn rate than going down the gravity as you would have higher possible turn rate because it is assisted by gravity, right?

[SinusoidDelta]

 

AoA spike(purple) can't be that high compared to pitch(green). Plane wasn't on that turn rate ever(!) during flight. There's been an ERROR in flight dynamics calculation process!

 

Re-read my post. This data isn't from your track or even an su-27 for that matter. It was an example of telemetry export from the F-15. That feature longer works though and never existed for the flanker.

 

So conclusion would be that: if your plane is fixed on max G limit on specific configuration then -if going up the gravity you would have lover possible turn rate than going down the gravity as you would have higher possible turn rate because it is assisted by gravity, right?

 

That sounds correct. For normal, velocity vector above the horizon flight, gravity is in opposition to the load factor and radial G is decreased. So, turn rate is lower and turn radius is larger. For inverted flight it's the opposite. Gravity assists the load factor, radial G increases, turn rate increases and turn radius decreases.

Edited October 7, 2016 by SinusoidDelta

[jackmckay]

That sounds correct. For normal, velocity vector above the horizon flight, gravity is in opposition to the load factor and radial G is decreased. So, turn rate is lower and turn radius is larger. For inverted flight it's the opposite. Gravity assists the load factor, radial G increases, turn rate increases and turn radius decreases.

 

Since English isn't my native language there could be an communication problem but that is what I was trying to explain by using quote 'I was inverted'. I'm glad we agree.

 

Next, based on that conclusion, keeping max allowed G for specific configuration, going inverted below horizon and with gravity assisted turn rate being increased, max allowed AoA limit would be higher than going above horizon (not inverted ofc) keeping same allowed max G, right?

[jackmckay]

Re-read my post. This data isn't from your track or even an su-27 for that matter. It was an example of telemetry export from the F-15. That feature longer works though and never existed for the flanker.

 

Ok, my mistake then. Even that telemetry looks similar to my Flanker maneuver in one part because roll rate increases, moderate pitch is given and AoA spikes up. .. but..

 

If both planes are part of FC3 package then why one can export telemetry and other can't? That's weird.

[GGTharos]

AoA permitted limit is not affected, it will be the same regardless of which direction you pull in - it has nothing to do with gravity.

 

However: The AoA experienced at a certain amount of G might vary depending on whether you are pulling with or against the gravity vector.

 

Next, based on that conclusion, keeping max allowed G for specific configuration, going inverted below horizon and with gravity assisted turn rate being increased, max allowed AoA limit would be higher than going above horizon (not inverted ofc) keeping same allowed max G, right?

[jackmckay]

AoA permitted limit is not affected, it will be the same regardless of which direction you pull in - it has nothing to do with gravity.

However: The AoA experienced at a certain amount of G might vary depending on whether you are pulling with or against the gravity vector.

 

Question: how much of certain amount of G that airframe feels in inverted dive might vary with respect to max AoA?

 

---

And the manual says this:::

---

 

4.10. Flight to aerobatics.

 

General information

 

The aircraft is allowed to perform a simple shape, complex and aerobatics in a wide range of speeds and altitudes within the permissible angles of attack and overload the ADF (ODA triggered) with the specifications set forth in this subsection.

This section examines the pilots on the aircraft with pendants, which are conditionally divided into groups:

Group 1 - a plane without suspension or 2hR-73E + 2hR-27R1 (P-27T1), or 2hR-73E + 2 AB caliber up to 500 kg, or 2hR-73E + 2xc-25, or 2hR-73E + 2hB -8M (2hB-13L);

Group 2 - plane with 4hR-73E + 6hR-27R1 (P-27T1) or 2hR-73E + 6 AB caliber up to 500 kg, or 2hR-73E + 4hB-8M (4hB-13L) or 2hR-73E + 4hS- 25;

Group 3 - aircraft with 2hR-73E + 8 AB caliber up to 500 kg or 2hR-73E + 16 AB caliber up to 250 kg.

 

A WARNING. With other options NOT suspensions perform aerobatics.

 

Features aerobatics on operational and combat training modes engines UR are virtually identical, except for the hill climb.

Pilotage performed only when the limiter angles α and Pu. Entering the limit angles of attack IPT overload accompanied by "focusing" (step increase efforts to handle 15 kg) and the stick shaker. This signal is displayed "alpha, Pu CRITICAL", followed by the speech information "maximum angle of attack, limiting overload".

ODA system with its correct operation provides high maneuverability of the aircraft at a safe piloting on the boundary limit angles of attack and overload.

 

A WARNING. Overriding "stop" when the maneuverability makes aerobatics significant growth, but can result in the aircraft stalling or excess Pu ext.

 

When creating the set overload rate of less than 2 seconds ODA triggered at small angles of attack and overload. The rate of release at the allowable angle of attack and overload determined by the "stop" while maintaining the pull force on the control stick.

For flights at altitudes below 5000 m and greater indicated a speed corresponding to M = 0,95-1,2 may occur rests on a roll and the pedals control knob due to insufficient power hydraulic drives flaperons and rudders, but in this case handling It is sufficient and is 25-30 ° per second.

Before performing aerobatics need to tighten (stall) shoulder straps. Check on the RD-15 position of the handle-OFF PRESSURE, which should be in the position PRESSURE.

 

---

I found this table:

 

...

5. Acceptable angles of attack:

 

A) For airplanes with no suspensions or SD

 

M ALM

0.5 24°

0.6 23°

0.7 22°

0.8 20°

0.9 19°

1.0 18°

2.0 8°

 

B) For airplanes with bomber means of destruction and the LDCs:

 

M ALM

0.6 20°

0.7 18°

0.85 15°

 

A WARNING. During takeoff - landing configuration (landing gear) αdop = 20 °. When you tap on the landing αdop = 16 °.

...

[DarkFire]

5. Acceptable angles of attack:

 

A) For airplanes with no suspensions or SD

 

M ALM

0.5 24°

0.6 23°

0.7 22°

0.8 20°

0.9 19°

1.0 18°

2.0 8°

 

 

Can't comment on the rest, but the above section is nicely consistent with the in-game observed onset of vibration at around 18-20° AOA with a clean configuration.

[jackmckay]

Flight data in moment of wing break:

aprox.

velocity. 950km/h

mach: 1.25

altitude: 7000m

AoA: 10deg

fuel. 65%

config: class 2 (4xR73 + 6xR27XX)

weight: 26500kg

 

.. max allowed AoA at this config should be between 18deg at mach 1 and 8 deg at mach 2.. roughly decreased by Group 2 config in 20% decrease of limit and fraction of G help due to inverted position going below horizon. So limit AoA should be for group 1 around 15,5deg for group 2 around 12,4deg worst case scenario. Even all of this should be monitored by pilot there is a 'Nadia' telling you 'ease out on the stick' and i'll make it harder for you so i will put some 15kg force on your stick so you can't excess G limit.

 

Why this limit is not implemented on su27?

and why cant we export flight telemetry from .trk files in DCS?

[DarkFire]

Why this limit is not implemented on su27?

and why cant we export flight telemetry from .trk files in DCS?

 

Early Su-27S aircraft had fixed Nadia settings that were set for a gross weight of 21,400 Kg. The system did not (does not) take in to account variations in weight or configuration. Nadia systems that take weight & other factors in to account were only available in much later Su-27 variants such as the S-30Mki, Su-35 etc.

 

It's interesting to consider what this might mean in terms of the intended purpose for the Su-27. 21,400 Kg. equates almost exactly with an Su-27 that has 2 x R-73 & 2 x R-27ER with 35% fuel, or a 4 x R-73 with 55% fuel configuration. These could reasonably be considered to be consistent with either an airfield defence interceptor profile or that of a longer range interceptor where WVR combat is assumed to take place after a lengthy flight and some BVR combat. It might therefore be reasonable to conclude that the original Nadia settings were designed for PVO and not VVS typical mission profiles.

 

I think it is possible to export telemetry data - isn't that exactly how Tacview creates ACMI files, via Lua export of telemetry?

[Ironhand]

Flight data in moment of wing break:

aprox.

velocity. 950km/h

mach: 1.25

altitude: 7000m

AoA: 10deg

fuel. 65%

config: class 2 (4xR73 + 6xR27XX)

weight: 26500kg

 

.. max allowed AoA at this config should be between 18deg at mach 1 and 8 deg at mach 2.. roughly decreased by Group 2 config in 20% decrease of limit and fraction of G help due to inverted position going below horizon. So limit AoA should be for group 1 around 15,5deg for group 2 around 12,4deg worst case scenario. Even all of this should be monitored by pilot there is a 'Nadia' telling you 'ease out on the stick' and i'll make it harder for you so i will put some 15kg force on your stick so you can't excess G limit...

Just passing through... I guess I don't understand this fascination with AoA. Max AoA has nothing to do with whether or not your wings tear off. It has everything to do with whether or not the wing stalls and you fall out of the sky like a rock with your wings still attached.

[lunaticfringe]

^this^

 

Its been said before, but AoA isn't G. Its also important to note that the faster you go, the greater the attainable G at lower AoA; if you're standing on stall speed, maximum AoA equates to 1G. If you're at corner, maximum AoA equates to your airframe G load rating. And if you're faster, maximum AoA is higher than what the aircraft can withstand.

 

So in your newest example, jackmckay- what was the G?