Su-27. Extreme G-loads... G=?

its the general case that jets fly fine until a catastrophic failure. that is the basis of why a2a missiles use expanding rod warheads, because its not so much the explosion that destroys the target as the overstress to the airframe caused when the shrapnel lacerates the skin -- the air tears the plane apart and it happens very very fast.

perhaps there would be some creaking; perhaps even if there was, the rate at which people g-load the frame in combat is so fast that you will progress into catastrophic failure before you can recover (if you're in over-g territory, then you're also likely outside of optimal roll rate territory). in any case, the better and more proper method to take precautions is to load the airplane according to the prescribed weight parameters and to have an awareness of your speed and your gs; your meters will let you know what your plane is doing far in advance.

flanker pilots may benefit from some cockpit time in a mig-15 to learn about energy management, that it's more than just keeping energy levels high -- that there's also an upper limit to how much energy you want to keep around.

for me, this has new significance to that bit in the manual citing the very experienced sukhoi test pilot commenting on how felt he couldn't even bring out the flanker's max potential; it's really no joke the plane requires finesse to fly.

the empty flanker still retains weapon rails so they account for something.

Found it.

- APU-470: 70 kg.

- AKU-470: 90 kg.

- P-72: 49 kg

So for a full Su-27 air-to-air loadout:

- 4x AKU-470(under- and between engine ducts for R-27R/ER): 360 kg.

- 2x APU-470(inner wing stations for R-27T/TE & R-27R/ER): 140 kg.

- 2x P-72(outer wing station for R-73): 98 kg

Total: 598 kg

Again I believe wingtip launchers(for R-73) are counted in aircraft empty weight as they are always mounted unless ECM pods are fitted.

Translated straight from the real СУ-27СК flight manual for reference.

Note the limitations through near the transonic region (0.85 < M ≤1.25)

Maximum operational overload at design

gross weight of 21,400 kg :

- Pu max = 8.0 at M≤0,85

- Pu max = 6.5 at 0.85 < M≤1,25

- Pu max = 7.0 for M > 1.25

For instruments that are different from the calculated gross weight ,

Overload is set at the rate of :

- M • Pu max = Const = 171,000 kg at M < 0.85 , but not

more than 9.0 =pu

- M • Pu max = Const = 139,000 kg at 0.85 < M≤1,25 but

not more than =7.0 pu

- M • Pu max = Const = 150,000 kg at M > 1.25 , but not

more than =7.5 pu

 

the empty weight doesn't change when swapping in the l005 pods

however, a clean configuration still names a weapon weight of 147kg, which may be the wingtip rails counted as weapons in order that the empty weight can remain a static figure? @74kg ea it seems like a plausible weight.

the empty weight doesn't change when swapping in the l005 pods

:hmm:

however, a clean configuration still names a weapon weight of 147kg, which may be the wingtip rails counted as weapons in order that the empty weight can remain a static figure? @74kg ea it seems like a plausible weight.

It sounds like the same 147 kg Ironhand was talking about - cannon ammo weight?

It sounds like the same 147 kg Ironhand was talking about - cannon ammo weight?

:doh:

oh yeah that :oops:

I don't know - hard to see a situation in the sim where you need anyway near the full fuel capacity.....half even.

Fly any multiplayer event. Fuel is a far more important resource than weapons.

Gameplay balance? What kind of balance is to pull infinity high G's with 9 tons of fuel and full weaponry? The maximum capacity of 9400kg fuel is uplifted only for long range, usually ferry flights or escort in best case. In Russian terms the subject internal volumes are actually called "internal drop tanks" meaning that they would only be filled if additional to the available in the other "regular" tanks fuel is needed. Having so much space in the fuselage the Su-27 actually doesn't need external drop tanks.

I admire this feature in the new update. The only thing that it brings to the gameplay is that people should now finally FLY the plane within it's limitations and things like BFM will become essential.

Interesting observation concerning this issue of Gs breaking the airframe, when judging Gs in Tacview. For anyone testing parameters, Tacview "reports" significantly lower Gs just before breakup than is actually occurring. For instance, while F2 view in the sim was reporting 11.2 G at the point of breakup, Tacview's last reported G was 5.8. In Tacview, there is then a blank period followed by breakup.

Anyone observing this?

To test which was in error, I replayed the flight pushing past Tacview's last reported Gs but paused the sim prior to the breakup Gs. I then took control and eased off the stick Gs. The wings stayed on.

... there is then a blank period followed by breakup.

 

Anyone observing this?

 

...

I confirm. And that is confused me in my first reaction.

what about pylones g limit ? Should it be like with the mig21 , your ordonance gets rip off when pulling too hard, or should it be the full wing first ?

I confirm. And that is confused me in my first reaction.

OK. Thanks for the confirmation. Tacview seems to consistently stop reporting about 6 Gs short.

Well, that's a matter to raise to the author, then :)

Good catch.

OK. Thanks for the confirmation. Tacview seems to consistently stop reporting about 6 Gs short.

IMHO this is based on how violent the maneuver is. If you go M1 and turn of ASC while pulling hard back you might only see 3-4 G in Tacview.

It could be that this is tied to how the frequency of the data going to Tacview.

IMHO this is based on how violent the maneuver is. If you go M1 and turn of ASC while pulling hard back you might only see 3-4 G in Tacview.

I observed this while doing testing which involved rolling to 110*, pausing, and then smoothly pulling the stick full back to load on Gs.

I was testing at M .8, M 1.0, & M 1.35 at gross weights of 21,400, 23,000, 25,000 and 27,000 kg. Haven't gotten to 29,000 kg yet. FCS was fully engaged the entire time. This issue only occurred in the M 1.35 regime because that's where the breakups occurred. And Tacview is not underreporting in the traditional sense. It stops reporting completely 6 units before breakup. There is then a data gap and the aircraft disintegrates.

Rich

Take a look at this track.

Stops reporting at 2G going 0.9 M.

2G_acmi.zip

Does the F-15 even need this "feature"? I mean, it's called the flying tennis court, it's huge wings make for a significantly lower wing-loading than the Flanker and thus should never enter the regime in where the wings would break off.

The thing is, many people think the Flanker is unflyable in this state and the F-15 is in arcade mode. But it's the other way around. The Flanker was in arcade mode with the ability to pull a Cobra at around M1.0 or even higher speeds. Did you ever break your wings off in the A-10C? If yes, did you change the way you fly the A-10C and did it happen again?

What the F-15 needs is proper damage modeling for overspeeding and/or gear down on high speeds. I was able to go M2.2 with bags on a few days ago.

Sure, but you'll just not reach conditions where you'll destroy the airframe. BAL for the eagle is 9g up to a GW of 68000lbs ... an eagle with two bags and air to air weapons is 55000lbs, an eagle with no bags, full fuel and missiles is 45000lbs.

The airframe is smaller and the wings shorter, it won't have as much trouble.

I agree about the landing gear ... AND the flaps.

Does the F-15 even need this "feature"? I mean, it's called the flying tennis court, it's huge wings make for a significantly lower wing-loading than the Flanker and thus should never enter the regime in where the wings would break off.

 

The thing is, many people think the Flanker is unflyable in this state and the F-15 is in arcade mode. But it's the other way around. The Flanker was in arcade mode with the ability to pull a Cobra at around M1.0 or even higher speeds. Did you ever break your wings off in the A-10C? If yes, did you change the way you fly the A-10C and did it happen again?

 

What the F-15 needs is proper damage modeling for overspeeding and/or gear down on high speeds. I was able to go M2.2 with bags on a few days ago.

Did you ever break your wings off in the A-10C? If yes, did you change the way you fly the A-10C and did it happen again?

 

I guess it's a little bit different. Flanker is a fighter, an interceptor, maneuvering at very high speeds. And breaking the wings can happen by accident. With the A-10C, to break the wings, you need to want it. Basically. But at the same time, in real life, a Flanker pilot would need to know what he's doing, and why it can't be the same in DCS? Just know what you are doing.. It won't break with training. And also, I tested it many times, it isn't so fragile as the people are saying. :) At least for me..

Also, breaking the wings in a fighter, example the Flanker, which is known by its maneuverability, that makes me/people think it's unbreakable?

do not touch asc button over 500kmph as real flanker drivers do.

with asc on, flanker behaves very normal as i excepted.

thanks DCS to show us what will happen when we disable asc at high speed:)

i guess real pilots newer wonder about closing asc at high speeds:)

Structural disintegration is not new to this sim. Back in the FC1/2 days the Su-25/T had the very same limit - fly it with flaps in combat position and no stores, speed up to 850-900 kph and pull hard on the stick. You can kiss your wings bye-bye...

The bottom line is we can never go wrong with modeled in-service limitation of the particular airframe. This will only makes virtual pilots more disciplined and improve the immersion. I'm sick and tired of online airquake. The pilot, even virtual, is first of all a thinking person, so lets not take away this primary function.

do not touch asc button over 500kmph as real flanker drivers do.

with asc on, flanker behaves very normal as i excepted.

thanks DCS to show us what will happen when we disable asc at high speed:)

i guess real pilots newer wonder about closing asc at high speeds:)

This.

There's a difference between line squadron pilots and the elite test pilots who we see doing insane things during airshow routines. Pilots like Anatoly Kvochur, Viktor Pugachev et al are the top 0.01%.

I'd bet that most line squadron pilots are instructed never to touch the direct mode switch in any circumstances outside of a failure of the FCS system, precisely because it represents such a risk to the aircraft and the pilot.

About DCS F15C limits... Eagle have only one small problem - water.

And yes, tacview not show G correcty. This eagle was in full +/- G in every maneuver with 3xF.Tanks, 8xAIM120. (...+ oil, pilot :D )

:doh:

Tacview-20160411-161444-DCS.txt.rar

Take a look at this track.

Stops reporting at 2G going 0.9 M.

That's the sort of thing I see, too.

Also, breaking the wings in a fighter, example the Flanker, which is known by its maneuverability, that makes me/people think it's unbreakable?

Maneuverability has nothing to do with this. It's very agile at LOW speeds, but negative relaxed stability comes at a price: high wing load. The limiter serves a purpose.

I sometimes think people just fly the wrong way. Always turn as hard as they can, pulling 2-digit g's, flying Mach 1.6 at 45k and jump-snipe on bandits. With some brain work you can easily reduce stress on pilot and airframe. But then again online competitive is always about kill/death ratio so people just jump into the pit, burn towards bullseye, drop their tanks, spam some missiles and then burn home. It seems no-one - or at least only a few - actually try flying responsively. It's the arcade mind in a simulation environment that stops you from improving.