Vermillion, here is my wing loading info

[Karnak]

Structual strength is almost never the issue in sustainable turns with WWII fighters.

Every WWII fighter that I am aware of will stall way before suffering a structural failure in a sustainable turn.

Instantaneous turns/snap turns are a whole different story.

In general the higher the wingloading, the fewer Gs it takes for the aircraft to depart controled flight.  There are several other factors, but an easily obtained, very rough estimate can be reached with wingloading data.

[niklas]

Originally posted by Karnak:


In general the higher the wingloading, the fewer Gs it takes for the aircraft to depart controled flight.

Iīd say departing controlled flight has more to do with wingdesign. You leave controlled flight wenn the outer wing (aileron) stalls. Thatīs why leading edge slats werenīt build over the whole wingspan for the 109 f.e. It would have allowed even higher AoA, but this advantage could not have been used due to harsh stall characteristics. The ailerons would have stalled first now, before the wingroot section stalls. Slats covering only the wingarea for the aileron allow aileron control while the wingroot section is already stalling.
This way you kept controlled flight and increased lift. The Spit went the opposite way, with thin wings (and a lot of washout?)it reduced the total lift to keep good aileron control near the stall.

This is at least my interpretation  

niklas

niklas

[gripen]

Well Karnak,
I'm not sure what you wanted to argue? Pretty much all WWII fighters could reach their structural limits (max sustained limit which normally were around 6-9g when breaking load factor were around 10-14g and safety coefficient 1,5-2) in the high speed turns or pulls or what ever maneuvers at low altitude. It is true that max sustained turns were around 2-4g but no one has argued otherwise here.

And high wingloading does not mean poor ability to sustain g specially at high altitude and high speed.

gripen

[HoHun]

Hi Gripen,

>Yeah, HoHun is mostly right but it should be noted that structural strenght is not allways limiting factor at high speed turns because compressebility constrains maneuverability specially at high altitudes.

Good point! It fits well with what I wrote, however, if you consider that corner speed increases with altitude until the aircraft will have difficulties actually reaching corner speed.

For example, an aircraft with a 110 mph stall speed at 1 G and a 9 G structural limit has a corner speed of Mach 0.43 at sea level. At about 23000 ft, it's corner speed will be Mach 0.68 - which is the P-38's critical Mach number. If our fictitous aircraft is similarly Mach limited, at higher altitudes, corner speed simply is beyond its capabilities.

By my definition, it can only make "low-speed turns (below corner speed)" above that altitude, though I admit that this term might be somewhat misleading as actually, the aircraft is going very fast :-)

Regards,

Henning (HoHun)

[gripen]

HoHun,
Actually you are missing my point. Very few WWII fighters could reach their structural limits in normal maneuvers (say turning or looping maneuvers) at high altitude. The critical mach number decreases when g load increases, forexample the P-38 had critical IAS about 290mph at 30k and 0-2g but with a bit over 3g load buffeting started around 200-250mph IAS and higher g loads caused buffeting or dive tendency at all speeds. See the AHT or manual. You can find similar phenomena from the manual of the F4U too.

gripen

[HoHun]

Hi Karnak,

>Every WWII fighter that I am aware of will stall way before suffering a structural failure in a sustainable turn.

Since you weren't specificially mentioning sustainable turns, I just decided to cover them all :-)

>In general the higher the wingloading, the fewer Gs it takes for the aircraft to depart controled flight.

Actually, it's not wing loading that counts but maximum available lift in relation to aircraft weight.

Regards,

Henning (HoHun)

[HoHun]

Hi Gripen,

>Actually you are missing my point.

You're right, I missed it! :-) Thanks for the info, that was new to me!

Regards,

Henning (HoHun)