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Slats have almost no effect on lift, their only real function is to increase critical aoa. They allow the 109 to pull higher coefficients of lift, but do not increase lift at a given cl.
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Which is why the effect of slats are not shown in the Russian tests. The tested turns are all sustained turns, ie. mild, 2-2.5 G turns at best. Without the slats opening, the 109 is just a fairly high wingloading aircraft with corresponding turn performance. The slats won't deploy in these mild turns, they don't make their effect felt; they deploy in the high-G, hard turns. That's why the 109 is generally described to 'shine' in hard, high-G turns.
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The problem with that is induced drag is proportional to the square of the CL, so whilst the 109 can pull higher cl, it does so at the expense of far more drag than the Spitfire.
Quite simply, larger wings generate less induced drag.
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Problem is, your little model misses a *slight* factor, that is that it's the wing that creates both drag and lift. An bigger wing also develops proportinally higher drag, it's not that it's just develops more lift without any extra drag.
To put it simply, the 109 has far less drag than the Spitfire. Yes, to obtain the same lift it needs higher AoA used, which increases drag greatly. But wheter the 109 has more drag at high AoA or it has still less drag when it has the same lift as the Spitfire, is something that needs to be worked out by calculation.
You've already posted the information
I posted a while ago but you did it selectively:
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Originally Posted by Hop The Russians tested turn times for aircraft. Their figures, all at 1,000m altitude:
109F4 - 19.6 - 20.5 secs (at 2900 kg)
109G2 - 22.6 (at 3235kg) 20 - 21.5 secs (at 3023kg)
109G4 - 21 secs (at 3027kg)
Spitfire Vb - 18.8 secs (at 2920kg)
Spitfire LF IX - 18.5 (at 3351kg) |
Let's see (added wingloading):
Bf 109G-2 : 20 secs* at 3023kg), using 1300 HP (187 kg/m2)
Spitfire LF IX - 18.5 at 3351kg, using 1690 HP (149 kg/m2)
Let's add Soviet fighters and see if your theory that wingloading is so important makes any sense...
Yak-3 - 17 seconds (2697 kg, 182 kg/m2) - 1290 HP
Yak-9 - 17 seconds (2870 kg, 167 kg/m2) -
Lagg3 - 18 seconds (2990 kg, 170 kg/m2)
La5FN - 19 secons (3290 kg, 188 kg/m2) - 1850 HP
La-7 - 18 secons (3315 kg, 189 kg/m2) - 1850 HP
* The Russians gave both left/right handed turns for the 109, turning to one side generally means better turn turn time because of torque. Wheter it's left or right depends on propeller rotation direction) It makes sense to use the optimal turn direction, as this was the case of the Spitfire as well.
Uh-oh. Something ain't right with your model.The Spitfire's big wings supposed to give 'much less drag', but then why do I see that with so much more power, the Spitifire actual turn times are not better and generally worser than the Soviet turn times.
Especially look at the Yak-3. This plane should be an awful turner, at least in Hop's world. It has a shitty engine with 400 HP less than the Merlin. It has the smallest wing area of the entire bunch and fairly high wingloading.
Ie.
Yak-3 - 17 seconds at 2697 kg, 182 kg/m2 - 1290 HP
Spitfire LF IX - 18.5 seconds at 3351kg, using 1690 HP (149 kg/m2)
Yet it convi
The Spitfire has 22.5 m2 wing area, the Yak much less 14.8 m2 wing area.
Explain please, how can it be that the Spitfire...
- with so much power : 1690 vs 1290
- with so much bigger wings : 22.5 m2 vs 14.8 m2
- with so much better wingloading : 149 kg/m2 vs. 189
...gets OUTTURNED by the Yak-3.
If we go by your model of how things work, the Spitfire should quite simply outturn the Yak-3, because it has much better wingloading, and if it has better wingloading, it is supposed to have less drag in turns, at least according to you. But it doesn't seem to work that way in real life...
What the Yak-3 DOES have however, is :
- extremely low drag
- extremely postive power-to-weight, power-to-drag ratio.
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The 109 can pull to higher AoA, possibly even generate enough lift to counteract the Spitfire's huge wing loading advantage, but it does so at the expense of enormous amounts of drag, which is why it can't turn as well as the Spitfire.
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As noted, the Spitfire's huge wing loading advantage already means that it has far more drag to start with. The Spitfire's 'huge wing loading advantage' also comes with huge drag because those huge wings create huge amounts of drag as well.
Especially considering that the Spitfire's big wings are not very good at creating lift/area... the Spit wing has washout on a large area, which effectively means that much of the wing is developing less AoA and lift than the rest. The Spit's wing is also of the thinnest profile of all WW2 fighters which means it actually develops the least lift per wing area. It's not an efficient lift-creating device. It was built for speed as a matter of fact. 1930s designers were fixated on the fast monoplane fighter. The Brits were no exception.
The huge wing was never meant for turns by it's designers, the only reason for it was that they needed to fulfill the RAF's requirement of houseing 8 machineguns in the wings, and they needed space (depth) for it.