Dive limits? Structural Limits?

[shift8]

Structural Limits?


Ok im not sure this is a issue so this is mostly for discussion, then it can be on the wishlist if its actually a problem.

I did a load of dive tests in AH and found some strange stuff.

Most planes seem to have mach limits of .75 to .80, so no problem here.

What was weird was that at low altitudes I could greatly exceed the structural limits. For example, in the P-51 was I was able to go right up the the mach limit of .80 even below 5000ft. According to the manual 505mph indicated in the limit, but Ive hit anywhere from 550 to 570 IAS in dives without damage. Same goes for the 109. 109s and spits were both limited to about 450-460 IAS at low alt due to structural failure.

So the questions is, is AH correct on this? I would imagine that any safety limit is actually higher than the actual limit, for example the P-51 is nominally limited to 8G but is actually capable of more like 12. Same for modern jets, there max G limits are not the actual limits. But is 70mph over the limit correct?

[Mitchell]

I AH you get a new plane every time you take off, in real life planes were used over and over.
Those limits were to prevent too much stress on the airframe that would weaken it over time.
They aren't a hard limit that suddenly causes a structural failure the first time they were exceeded.

[save]

Every time I a A20 doing high-G dogfighting with bombs I would like to see they fall apart from structural damage.

[pembquist]

I don't know how accurate overloading damage is but keep in mind that structural limits are probably safe structural limits. With GA airplanes there is a load limit factor of 1.5 meaning that for an aircraft with a limitation of 6g it should not be permanently deformed or weakened by being stressed at anything less than 9g.this is not the same thing as safe to 9g, but you take my point that a limit from an operating manual has a factor of safety and bending wings is not the same as having them come off, (though very close.)

[cobia38]

Every time I a A20 doing high-G dogfighting with bombs I would like to see they fall apart from structural damage.

 They do if you exceed the load limits silly

[Zimme83]

Underwing bombs can in some cases help u to prevent ripping of your wings in a turn, dont know if A-20 is one of those cases. The forces on the wing from the bombs is working in opposite direction from the forces coming from lift in a high G turn. Only bombs in bomb bay is more dangerous.

[FLS]

Underwing bombs can in some cases help u to prevent ripping of your wings in a turn, dont know if A-20 is one of those cases. The forces on the wing from the bombs is working in opposite direction from the forces coming from lift in a high G turn. Only bombs in bomb bay is more dangerous.

Doesn't the weight of the bombs increase the required lift for a given load factor? A 4g load factor with 2 500lb bombs adds 4000 lbs to the lift force on the wing.

[Zimme83]

Yes it does, the turn ability will suffer since the plane is heavier. But in a hard turn the forces on the wings is pulling them upwards (inwards in the turn) ords under the wings (or fuel in them)  Will add a force that works in opposite direction (outwards) and thus canceling the lift forces to some extent.
U can of cource get other problems with structural integrity when u add 6G to a 1000lbs bomb under the wing.

[FLS]

You don't "cancel" the lift forces when you have a lower load factor at a greater weight. You've still increased the load on the wings, you just get less radial g as a result. Radial g is not the problem. The problem is the lift force. Radial g is just an indicator of lift force for a given weight.

[Zimme83]

Ok, u didnt get what i mean..
Yes the lift force on the wing is the same, yes, the higher weight gives higer wing loading and decreased turn ability.
 But the forces from lift cause the wings to bend upwards and if u add weight to the wing, fuel or bombs, the centrifugal force from the extra weight pulls the wing downward. And 2 forces working in opposite directions cancel each other out. Point is: Bombs under wings does not increase risk of snapping wings off. U will have the same amount of lift aviable but less strain on the wing (and poorer turn performance)

Heavy fuselage + light wings = High strain on wings
Light fuselage + heavy wing = Less strain on wings.

Turn ability is affected by the total weight of the plane but the strain on the wings is also affected by where on the plane the weight is placed.

[FLS]

I got that the first time. You don't have to repeat it.

For a given radial g the load is greater when the weight increases. Since the load is greater there is more stress. I don't believe it cancels out but I haven't looked into it. It seems likely that hanging a mass under the wing increases stress for all maneuvering loads.

[Zimme83]

Ok.... we just leave it..

[pembquist]

On a side note, who says the main wing is the first thing to fail catastrophically. Was it the Typhoon that kept shedding tails in power dives? It kept coming apart halfway back from the cockpit. So....placing the load out on the wing might spare the spar but another piece might break.

[MK-84]

Every time I a A20 doing high-G dogfighting with bombs I would like to see they fall apart from structural damage.

Loaded the A20 will break apart more easily then unloaded.

[bozon]

Loaded the A20 will break apart more easily then unloaded.

In reality it depend where the bombs are loaded (belly or wings) because it affects the distribution of the forces across the wing. In the game I suspect that the model only has a total force threshold regardless of how the weight is distributed - but I do not really know.