Damage due to overspeed, over-g etc.

[Baikingu]

I understand the “limits” is for safety/longevity.
But when said limits are exceeded by quite a margin. And several times/long periods of time. there is bound to be consequences eventually. 
like if someone 10+ times janks on the stick with pulling paddle switch making the Hornet do peak g’s of say 10 g’s (7,5 g limit loadout).
Or a 16 doing 1000 knots (800 knot “limit”) at 10k for minutes chasing down someone.

 

The limits do have a safty buffer most likely. But when even the safety buffer is exceeded thats when things would start taking damage/breaking.

 

its like your rev. Limit on a car. You can drive at the rev. Limit for a while. But eventually, possibly suddenly the engine will fail

Edited December 18, 2020 by Baikingu

[nighthawk2174]

In terms of the hornet I have doubts it would do much beyond having an unacceptable impact on longevity and up time due to necessary inspections.  Now I’m not saying pulling 9+ g’s multiple times couldn’t have some impact.  Such as potentially causing hung stores.  But, on the scale DCS is dealing with, airframe wise being new every flight, I just don’t see it being catastrophic.  
 

As I said before though there may be exceptions and the f16 over speed may be one of them.  And is worth investigating.

Edited December 18, 2020 by nighthawk2174

[Baikingu]

It would be nice to have hung stores/malfunction etc. from overstress though.
I'm not saying we should suddenly "explode" from overstressing the aircraft's (like the 14 over g'ing).
But some potential negative impact (as realisticly as possible) would make/force players to take a bit care.
This could/would ofc. have the option to be disabled server side.

[randomTOTEN]

2 hours ago, Baikingu said:

It would be nice to have hung stores/malfunction etc. from overstress though.

They do for some modules in some conditions. Why do you keep asserting otherwise?

 

 

Edited December 18, 2020 by randomTOTEN

[nighthawk2174]

6 hours ago, Baikingu said:

It would be nice to have hung stores/malfunction etc. from overstress though.
I'm not saying we should suddenly "explode" from overstressing the aircraft's (like the 14 over g'ing).
But some potential negative impact (as realisticly as possible) would make/force players to take a bit care.
This could/would ofc. have the option to be disabled server side.

 

Ehh I just don't think there's really any negative impacts (again in terms of DCS here) airframe wise beyond hung stores.  But the big question is how likely are they to hang?  IIRC for the F35 no such G limits on any ordinance exist even for older weapons with "hard" limits on other jets (I could be wrong don't quote me on this).  And as is pointed out in the doc I posted earlier.  How many of these limits aren't due to them being actual limits but just a lack of testing.  So hard to really put a "realistic" twist to hung stores.

[85th_Maverick]

On 12/18/2020 at 8:54 AM, nighthawk2174 said:

....

Something worth considering pretty much every jet is going to be built with a F.S. (factor of safety) where the "limits" aren't the maximum possible the jet can take (there will be exceptions ofc).  Rather it would just have negative impacts on the longevity of the airframe.  Which for 40+ million dollar jet is a big deal.  Hence stuff like the F14 being limited to 6.5G (7G?) during peacetime.  And instances of F15's pulling 12+ G's without the airframe suffering any damage.  There's also a few stories i've heard of hornets pulling 9+ g and the worst that happened was one of the engine bay doors was slightly bent.  So we should just be careful in making it so something, that yes is bad for the longevity (in terms of decades/ 10's of thousands of flight hours) of an airframe, but normally wouldn't be catastrophic is made so just because of limits meant to preserve the longevity of something.

 

Yes, for those who didn't think of it, the design limit load is usually 1.2 to 1.5 times lower than the real limit giving a 100% fuel load in the fuselage, limit for which the structure is starting to fail (not actually failing, but starting to and will eventually fail within a matter of seconds), yet not limited to just those safety factors as you also mention! But, considering that a MIG-29 in DCS seems to have a safety factor of 2 (which I find exaggerated) as the wings start ripping of above 18Gs with no loadout on the belly and with 100% internal fuel, the modern Su-27 (not the original T-10 which indeed lost a wingtip at some high G-loads during trials) and Su-33 (especially the Su-33 which has a reinforced all-around airframe) should actually have a more decent safety factor of 1.3...1.4 with full internal fuel, not ~1.06 as it is right now as the Su-27 loses both wings at just 9.5Gs with no belly loadout and with 100% fuel. The Su-27/33 are having their wings ripped off a bit too soon!

Here are the tracks for proof:

 

MIG-29 very high on structural G-limit.trk Su-27 a bit low on structural G-limit.trk

[bies]

On 4/29/2021 at 12:09 AM, 85th_Maverick said:

as it is right now as the Su-27 loses both wings at just 9.5Gs with no belly loadout and with 100% fuel.

 

According to Su-27SK manual 9G with 100% fuel is way, way above the limit.

From my head: Su-27SK was allowed to squeeze 9G only below Ma=0.85 and only with 20% internal fuel + 2xR-73 and 2xR-27.

 

Structural damage at 9,5G with full fuel supersonic is already really big safety factor.

 

Su-27SK for normal takeoff weight 60% fuel + 4AAM:

Quote

Maximum service G at design flight weight of 21,400 kg

G max = 8.0 at M < 0.85

G max = 6.5 at 0.85 < M > 1.25

G max = 7.0 at M > 1.25

Notice transonic region is considered more stressful than supersonic.

 

In case of Su-27 everything above 60% internal fuel is considered as "internal drop tank", it was the reason of some considerable scuffle between design bureau and Soviet military.

That's why when you set Su-27 in mission editor it has only 59% internal fuel as default setting, when all other fighters have 100%

 

I think ED has a good idea about Su-27 realistic limits.

Edited June 2, 2021 by bies