No more above 12G turns

[Bushmanni]

Perhaps I'm misunderstanding the question but since the higher you go, the lower the true airspeed the Mach number represents, you have to go faster at higher altitudes to have the same available Gs.

 

The chart already considers mach number dependence separately.

 

Metal fatigue happens when the metal bends ie. static load doesn't cause metal fatigue except when the load is applied. If you apply a steady 9G load, you can keep it essentially indefinitely as long as it's within allowable limits. It's the repeated loading and unloading that causes fatigue. From this point of view it could be speculated that high G and buffeting uses more flight hours than high G without buffeting and OWS has been programmed to preserve flight hours.

Edited May 23, 2016 by Bushmanni

[SinusoidDelta]

The OWS takes all engineering factors into account (gross weight, roll, asymmetric stores, etc.) then computes and displays the max (and minimum) available load factor (G) at that configuration. When OWS is recalled on the VSD, a severity code is displayed along with percentage of load limit factor reached by each control surface and what action should be taken. This is to ease the burden on maintenence so they don't have to inspect every nut and bolt when a percentage of overload condition is reached. The severity codes are ordered 0 - 6 in proportion with the design limit load, 0=80%-100%, 1=100% and so on, 6 being 140%. Keep in mind the OWS along with the Aircraft Structural Integrity Program (ASIP) (and like most things on the Eagle) has been significantly revised since introduction.

[JunMcKill]

The OWS takes all engineering factors into account (gross weight, roll, asymmetric stores, etc.) then computes and displays the max (and minimum) available load factor (G) at that configuration. When OWS is recalled on the VSD, a severity code is displayed along with percentage of load limit factor reached by each control surface and what action should be taken. This is to ease the burden on maintenence so they don't have to inspect every nut and bolt when a percentage of overload condition is reached. The severity codes are ordered 0 - 6 in proportion with the design limit load, 0=80%-100%, 1=100% and so on, 6 being 140%. Keep in mind the OWS along with the Aircraft Structural Integrity Program (ASIP) (and like most things on the Eagle) has been significantly revised since introduction.

 

I agree with you delta, what we are discussing, is that given the information we have, what really happens to every aircraft?, in this case SU-27 vs F-15 in extreme overload maneuvers, ED decided that the SU-27 will break apart the wings, while the F-15 not, I think this discussion would end if ED post the technical information that led them to make that decision on the Su-27. In the end, we are the customers, isn't it?

Edited May 24, 2016 by JunMcKill

[GGTharos]

ED did post that information, and it was straight from the flanker manual.

 

They pointed to the design limits in tonnes.

 

The decision to damage the airframe was theirs, and they will break the wings at 1.5xdesign limit.

 

I suspect you won't do any damage to the airframe at all up to 1.33xdesign limit.

 

IIRC it was:

 

171t/gw <= 0.85M

0.85M < 139t/gw <= 1.25M

1.25M < 151t/gw

 

Where gw is the gross weight in metric tons.

 

The main reason was realism and the abuse of the 'magic s key', which granted 20g 180 turns without blacking out (because it happened so fast).

 

Yes, the F-15 can do some things it shouldn't, as Frostie demonstrated, but I don't see the actual advantage in it - you can't hold that G without blacking out (unless G effects are off), and it isn't very useful over all; so yes, it shouldn't happen but also there's no urgency in fixing something that has none or minimal effect.

 

Frogfoot already said they will be doing some things as far as the F-15 is concerned, but there were no details.

 

I agree with you delta, what we are discussing, is that given the information we have, what really happens to every aircraft?, in this case SU-27 vs F-15 in extreme overload maneuvers, ED decided that the SU-27 will break apart the wings, while the F-15 not, I think this discussion would end if ED post the technical information that led them to make that decision on the Su-27. In the end, we are the customers, isn't it?

[JunMcKill]

As I told before, we all love realism, and we all want that ED simulations be the best in the world! You can even add the loss of weapons in the SU-27 when the speed exceed for long time the hardpoint limits, but as many have posted, it's difficult to believe that a F-15 can keeps their wing bags attached above 12 or more Gs! But thanks for the info anyway!

 

ED did post that information, and it was straight from the flanker manual.

 

They pointed to the design limits in tonnes.

 

The decision to damage the airframe was theirs, and they will break the wings at 1.5xdesign limit.

 

I suspect you won't do any damage to the airframe at all up to 1.33xdesign limit.

 

IIRC it was:

 

171t/gw <= 0.85M

0.85M < 139t/gw <= 1.25M

1.25M < 151t/gw

 

Where gw is the gross weight in metric tons.

 

The main reason was realism and the abuse of the 'magic s key', which granted 20g 180 turns without blacking out (because it happened so fast).

 

Yes, the F-15 can do some things it shouldn't, as Frostie demonstrated, but I don't see the actual advantage in it - you can't hold that G without blacking out (unless G effects are off), and it isn't very useful over all; so yes, it shouldn't happen but also there's no urgency in fixing something that has none or minimal effect.

 

Frogfoot already said they will be doing some things as far as the F-15 is concerned, but there were no details.

[GGTharos]

With bags attached, no problem - with bags attached AND full, that's another story.

 

In any case, if you look carefully you'll see that if you just dropped an F-15 into the air with full payload and a full centerline, OWS still lets you do 9g at the peak power/corner speed of the aircraft at each altitude. It's probably not a coincidence. What will happen if you're going a bit faster is that the OWS will register an over-g and flag some components for inspection.

 

As for pulling 12g, I think the main issue is stuff attached to the wings - as SD pointed out with the incident that he dug up, that's the only instance of a (as far as we know) non-fatigued F-15 breaking up in mid-air due to over-g.

However, as he also pointed out, there's no actual report which is a problem.

 

On the other hand, we have numerous records of over-g including up to 12g+ without airframe failure (but warping in one or two cases). Most over-g is less though, 10-11, with incidents being more rare the higher you go. I don't think they had anything resembling full wing tanks though :)

[JunMcKill]

You're right, most if the 30+ Gs posted are in MP with lag, a friend of mine was making test with the F-15, and I told him to make everything in single player (analyzing the information of the track vs Tacview), he told me that in single player the max Gs he reach was 12, but will make the test with bags full and weapons.

 

With bags attached, no problem - with bags attached AND full, that's another story.

 

In any case, if you look carefully you'll see that if you just dropped an F-15 into the air with full payload and a full centerline, OWS still lets you do 9g at the peak power/corner speed of the aircraft at each altitude. It's probably not a coincidence. What will happen if you're going a bit faster is that the OWS will register an over-g and flag some components for inspection.

 

As for pulling 12g, I think the main issue is stuff attached to the wings - as SD pointed out with the incident that he dug up, that's the only instance of a (as far as we know) non-fatigued F-15 breaking up in mid-air due to over-g.

However, as he also pointed out, there's no actual report which is a problem.

 

On the other hand, we have numerous records of over-g including up to 12g+ without airframe failure (but warping in one or two cases). Most over-g is less though, 10-11, with incidents being more rare the higher you go. I don't think they had anything resembling full wing tanks though :)

[DarkFire]

ED did post that information, and it was straight from the flanker manual.

 

They pointed to the design limits in tonnes.

 

The decision to damage the airframe was theirs, and they will break the wings at 1.5xdesign limit.

 

I suspect you won't do any damage to the airframe at all up to 1.33xdesign limit.

 

IIRC it was:

 

171t/gw <= 0.85M

0.85M < 139t/gw <= 1.25M

1.25M < 151t/gw

 

Where gw is the gross weight in metric tons.

 

The main reason was realism and the abuse of the 'magic s key', which granted 20g 180 turns without blacking out (because it happened so fast).

 

This. ED have implemented the design limits as published in the actual Su-27S flight manual by Sukhoi. The tests that Ironhand and others did showed that the aircraft generally won't suffer structural failure until G=>150% of design limit. I've never known an engineer that didn't build in a safety margin so this failure level is entirely consistent with general design paradigms.

 

As for the insta-fail behaviour, everything I've read and my own personal experimental experience (I used to be a physicist before I did what I do now) is again entirely consistent with repetitive strain-induced failure in high-tensile steel and/or aluminium alloys.

 

We can query whether the FBW system on the Su-27 behaves correctly (I believe it has a few minor unrealistic quirks, but none that effect maximum G) and whether it's programmed for taking weight in to consideration, but the behaviour of the airframe in the game appears to be entirely consistent with published figures and physical reality.

[JunMcKill]

This. ED have implemented the design limits as published in the actual Su-27S flight manual by Sukhoi. The tests that Ironhand and others did showed that the aircraft generally won't suffer structural failure until G=>150% of design limit. I've never known an engineer that didn't build in a safety margin so this failure level is entirely consistent with general design paradigms.

 

As for the insta-fail behaviour, everything I've read and my own personal experimental experience (I used to be a physicist before I did what I do now) is again entirely consistent with repetitive strain-induced failure in high-tensile steel and/or aluminium alloys.

 

We can query whether the FBW system on the Su-27 behaves correctly (I believe it has a few minor unrealistic quirks, but none that effect maximum G) and whether it's programmed for taking weight in to consideration, but the behaviour of the airframe in the game appears to be entirely consistent with published figures and physical reality.

 

I'll ask you a very simple question , you as physicist, think that is possible for a F-15C to keep the wings bags attached after multiple barrel rolls, with those bags full of fuel and in the same hardpoint two missiles, flying at 573 knots IAS (1,061.19 km/h=0.87M) and pulling to 14.5Gs? Take a look, tested in single player, no lag. (minute 1:06)

 

DuUQ6Oq7xoM

Edited May 25, 2016 by JunMcKill

[DarkFire]

I'll ask you a very simple question , you as physicist, think that is possible for a F-15C to keep the wings bags attached after multiple barrel rolls, with those bags full of fuel and in the same hardpoint two missiles, flying at 573 knots IAS (1,061.19 km/h=0.87M) and pulling to 14.5Gs? Take a look, tested in single player, no lag. (minute 1:06)

 

Well, let's do some back-of-the-envelope calculations.

 

The F-15C drop tank is listed as having a capacity of 610 gallons. If these are US gallons this = 2,309 litres.

 

The specified density of JP-8 fuel is listed as being 0.77 Kg/L at 15 degrees C, so the weight of fuel carried in a single drop tank at 15 degrees = 1,778 Kg.

 

I've been unable to find the weight of a dry 610 gal. drop tank, but everything I've read suggests that they're metal as opposed to the kevlar ones used on later models of the F-18, and I've seen some posts elsewhere by ex-USAF techs that suggested the empty weigh to be in the region of 100 Kg.

 

So, the total weight of the tank fully fuelled ~ 1,880 Kg.

 

At 14.5G the force experienced by the pylon will therefore be 27,260 Kg.

 

It appears that each tank is attached to the pylon by two lugs or rings. Assuming equal force distribution, at 14.5G each lug / ring would therefore experience a force of 13,630 Kg which is 30,049 lb.

 

Can't say for sure whether it would remain attached at this force level without knowing the specified properties of the material from which the lugs are made, the engineering design etc. but my first reaction would be nope, not a chance in hell. The actual force experienced by the pylon will be larger due to the weight of the two missiles and also during a barrel roll there will likely be a component of drag force operating vertically on the tank, further adding to the total force on the pylon, in addition to a centrifugal force due to the rotation of the aircraft.

 

So to answer your question, no I don't believe that it's realistic at all for the tanks to remain attached at this G level.

Edited May 25, 2016 by DarkFire

[GGTharos]

It shouldn't be able to pull 14g probably, just to start with.

 

On the other hand, what's the utility of these contrived maneuvers? :)

 

I'll ask you a very simple question , you as physicist, think that is possible for a F-15C to keep the wings bags attached after multiple barrel rolls, with those bags full of fuel and in the same hardpoint two missiles, flying at 573 knots IAS (1,061.19 km/h=0.87M) and pulling to 14.5Gs? Take a look, tested in single player, no lag. (minute 1:06)

Edited May 25, 2016 by GGTharos

[JunMcKill]

It shouldn't be able to pull 14g probably, just to start with.

 

On the other hand, what's the utility of these contrived maneuvers? :)

 

The only utility of the maneuvers in this case, is to show to F-15C pilots that in DCS, they are flying an UFO! :pilotfly: at the same way that people complained the SU-27 with FBW off (magic button) and high Gs, fully armed at high speed were unrealistic

Edited May 25, 2016 by JunMcKill

[JunMcKill]

Thanks Darkfire for your calculations and time, we got similar results (yours are better) doing maths!

 

Well, let's do some back-of-the-envelope calculations.

 

The F-15C drop tank is listed as having a capacity of 610 gallons. If these are US gallons this = 2,309 litres.

 

The specified density of JP-8 fuel is listed as being 0.77 Kg/L at 15 degrees C, so the weight of fuel carried in a single drop tank at 15 degrees = 1,778 Kg.

 

I've been unable to find the weight of a dry 610 gal. drop tank, but everything I've read suggests that they're metal as opposed to the kevlar ones used on later models of the F-18, and I've seen some posts elsewhere by ex-USAF techs that suggested the empty weigh to be in the region of 100 Kg.

 

So, the total weight of the tank fully fuelled ~ 1,880 Kg.

 

At 14.5G the force experienced by the pylon will therefore be 27,260 Kg.

 

It appears that each tank is attached to the pylon by two lugs or rings. Assuming equal force distribution, at 14.5G each lug / ring would therefore experience a force of 13,630 Kg which is 30,049 lb.

 

Can't say for sure whether it would remain attached at this force level without knowing the specified properties of the material from which the lugs are made, the engineering design etc. but my first reaction would be nope, not a chance in hell. The actual force experienced by the pylon will be larger due to the weight of the two missiles and also during a barrel roll there will likely be a component of drag force operating vertically on the tank, further adding to the total force on the pylon, in addition to a centrifugal force due to the rotation of the aircraft.

 

So to answer your question, no I don't believe that it's realistic at all for the tanks to remain attached at this G level.

Edited May 25, 2016 by JunMcKill

[DarkFire]

Thanks Darkfire for your calculations and time, we got similar results (yours are better) doing maths!

 

No problem :) From the perspective of a player with zero programming skills, as some of the in-game aircraft (is it the MiG-21?) have stores that can be damaged or torn off by excessive G, I'd like to think that it would be possible for this to be implemented for all the in-game aircraft. I won't use the "b" word, but it would perhaps... level the playing field... to a degree.

 

Maybe part of the controversy is that as virtual pilots there's little to no disincentive for doing things that would be so dangerous as to be unthinkable for real AF pilots, no matter what aircraft we like to fly. Certainly some of the things we've all discussed are in reality probably extreme edge cases that would only actually happen incredibly rarely.

 

Maybe I should put it like this: certainly the Su-27 and F-15C are based on different design philosophies, with different implemented parameters resulting in different capabilities. Personally I think it would be beneficial to all of us if they could be modelled to the same degree of realism. Hopefully that's something that's planned for future updates :)

[JunMcKill]

Yeah I think ED is doing their best to make the simulation closest to reality as can be, that's for simmers. And for gamers, with only set the option GAME, they can enjoy simple flight model to make what they want!

 

No problem :) From the perspective of a player with zero programming skills, as some of the in-game aircraft (is it the MiG-21?) have stores that can be damaged or torn off by excessive G, I'd like to think that it would be possible for this to be implemented for all the in-game aircraft. I won't use the "b" word, but it would perhaps... level the playing field... to a degree.

 

Maybe part of the controversy is that as virtual pilots there's little to no disincentive for doing things that would be so dangerous as to be unthinkable for real AF pilots, no matter what aircraft we like to fly. Certainly some of the things we've all discussed are in reality probably extreme edge cases that would only actually happen incredibly rarely.

 

Maybe I should put it like this: certainly the Su-27 and F-15C are based on different design philosophies, with different implemented parameters resulting in different capabilities. Personally I think it would be beneficial to all of us if they could be modelled to the same degree of realism. Hopefully that's something that's planned for future updates :)

[*Rage*]

BST /= ED

[GGTharos]

The difference is that the Su-27 magic S button gave you a 180 without consequences at high speed (both in kph and dps :) )

You don't get anything out of these g's in the eagle.

 

The only utility of the maneuvers in this case, is to show to F-15C pilots that in DCS, they are flying an UFO! :pilotfly: at the same way that people complained the SU-27 with FBW off (magic button) and high Gs, fully armed at high speed were unrealistic

[DarkFire]

BST /= ED

 

True, but I'd like to think that useful 3rd party dev code gets shared with ED and can be folded back in to the base game.

[fyaruny]

Sorry for bumping this thread again but im getting relly mad when playing online because of this. It may be realistic but it gives a huge unadvantage over the f-15 or other aircrafts because they can simply pull a high amount of G's when dodging my missles while i can't. I sometimes try dodging a missle but im still a noob and get too nervous to check the G meter and sudently i hear a bang thinking the missle got me but then i realise it didn't, my wing just break apart.

Im starting to think the su-33 is a more viable option now.

[codefox]

Im starting to think the su-33 is a more viable option now.

 

It will eventually get the same treatment once the PFM knocks on the door, I'd guess it's safe to say that.

However, the operational limits (real-life) of the Su-27 are lower than that of the F-15. The currently modeled behavior appears to be mostly correct, as you can read throughout this thread.

 

Also, I really don't see this giving the Flanker a huge disadvantage as long as you know what you're doing. Before that change, you were able to pull more than 40(!)Gs. That's what I'd call an unfair advantage. :)

[fyaruny]

It will eventually get the same treatment once the PFM knocks on the door, I'd guess it's safe to say that.

However, the operational limits (real-life) of the Su-27 are lower than that of the F-15. The currently modeled behavior appears to be mostly correct, as you can read throughout this thread.

 

Also, I really don't see this giving the Flanker a huge disadvantage as long as you know what you're doing. Before that change, you were able to pull more than 40(!)Gs. That's what I'd call an unfair advantage. :)

 

Yea i agree with you, but anyway, don't you think that while they don't upgrade the su-33 flight model, using the 33 right now has an advantage (altho its unrealistic) over the 27?

[Stuge]

Having others pilot the Su-33 while I pilot Su-27 is actually an advantage for me.

 

Choosing the 33 over 27 online indicates a possible lack of skill of the pilot.. although it may also be a cunning deception :)

 

Oh and the 33 can't pull off any cool stunts in a dogfight...

[fyaruny]

Having others pilot the Su-33 while I pilot Su-27 is actually an advantage for me.

 

Choosing the 33 over 27 online indicates a possible lack of skill of the pilot.. although it may also be a cunning deception :)

 

Oh and the 33 can't pull off any cool stunts in a dogfight...

 

Haha ok i might give a try on the 33 online and take the conclusions :P

[GGTharos]

No, it just means that you don't know how the limits of the 27 and how to adjust in order to deal with them.

 

Don't want your wings to come off?

 

Limit the GW during heavy maneuvering - don't take full fuel, launch/jettison your heavy missiles, stay below M0.9.

 

Your wings will be just fine.

 

That means:

 

You have to plan how close you'll get to bandits while you've got those 350kg missiles on-board.

You have to plan how you'll use fuel. Why are you taking 9 tons when you'll die with 6 tons onboard?

You have to realize that being surprised when you're heavy (or in most situations) = doom

You have to realize you'll be expending more missiles just to keep bandits away.

you have to realize that you can't really dodge missiles with knee-jerk 12g stick-yanks.

 

Yea i agree with you, but anyway, don't you think that while they don't upgrade the su-33 flight model, using the 33 right now has an advantage (altho its unrealistic) over the 27?

[fyaruny]

No, it just means that you don't know how the limits of the 27 and how to adjust in order to deal with them.

 

Don't want your wings to come off?

 

Limit the GW during heavy maneuvering - don't take full fuel, launch/jettison your heavy missiles, stay below M0.9.

 

Your wings will be just fine.

 

That means:

 

You have to plan how close you'll get to bandits while you've got those 350kg missiles on-board.

You have to plan how you'll use fuel. Why are you taking 9 tons when you'll die with 6 tons onboard?

You have to realize that being surprised when you're heavy (or in most situations) = doom

You have to realize you'll be expending more missiles just to keep bandits away.

you have to realize that you can't really dodge missiles with knee-jerk 12g stick-yanks.

 

ah thanks ggtharos, that clears up my mind and im starting to realise what im doing wrong.

i have been playing on the 104th lately so im allways full of fuel and im allways full of missiles, i dont even bring the ecm pods because i like those 2 extra r73 but i really never use the 4 of them tho lol. I also have to practice the missile dodging a little more.

Talking about the 350kg missiles, are you talking about the 27er ? and by lowering the number i carry will reduce my chance to break my wings apart since they are carryed on the aircraft belly ? i think i cant dismiss those two 27et because they are really handy, and those four 27er also come in handy. The only missiles i think i could dismiss are the two r73 but i dont know how much do they weight comprared to the jammer pods, is it a big diference ?

thanks