Bf-109F-4 and a bleak time for RAF

Hop · Dec 15, 2006

Hop,

Stop trying to put words into my mouth, I never claimed the slats increase lift at any given AoA, however as the critical AoA is reached (Which it is emmidiately in a tight turn) they deploy, increasing the critical AoA and thereby lift.

No, you claimed they increased lift AND Aoa:

The slats increases the lift by 25% in the covered areas, and the critical AoA of the entire wing is increased as-well, allowing for a much tighter turn.

The Bf-109 has 48% of its wings covered by the slats, which means roughly a 12.5% increase in lift and still a 25% increase in available AoA.

You can say "slats increase lift", which is correct although greatly simplified. You can say "increased AoA increases lift" which is more accurate. But when you say "slats increase lift and AoA" you are wrong, because the slats increase critical AoA, and the AoA increases lift.

Now sure when the Bf-109 turns at its tightest, tighter than the Spitfire, its going to create more drag, thats logical - The tighter the turn, the more the drag. Drag is a biproduct of lift.

Again, no. The 109 has to pull a higher CL to equal the Spitfire's turn, because it has a much higher wing loading. That means at the same turn as the Spitfire, the 109 is generating more induced drag.

And as to your claim that the slats don't increase lift, well thats total bullsh*t Hop. The slats delay the onset of stall by increasing the critical AoA, and the higher the AoA the higher the lift

Which is exactly what I said. The slats do not increase lift at a given AoA (unless that AoA is at the limit of critical AoA)

And as to the increase in drag, well fortunately the 109 is very small and has a very low power-loading, so although the 109 suffers from more drag pr. area in a tight turn, tighter than the Spitfire, it makes up for that in power and small size.

Which doesn't seem to be supported by any tests I have seen.

Also your "big wing" theory is so very flawed. A big wing does not simply create less induced drag than a smaller one.

Yes, it does. The bigger the wing (at a given weight, ie the lower the wingloading) the lower the induced drag, because induced drag is proportional to the square of CL. Basically, a smaller wing has to pull a higher AoA to generate the same lift as a larger one, which means higher induced drag.

Oh and about the Russian tests Hop, you forgot to mention that the 109G-2 was equipped with gun-pods.

I think that the first weight is with gunpods, the second without. That should be fairly obvious from the two quoted weights.

Glider · Dec 15, 2006

There is obviously a debate going on here and I would ask two questions.

1 I always understood that the key problem with the 109's slats wasn't if they worked or not but the way they deployed. When entering a tight turn one wing is going faster than the other with the result that the slats could deploy unevenly. This inevitably caused the plane to lose for a precious moment its smoothness, causing an alarming shudder or vibration, giving the opposing plane a momentary advantage.

2 If the secret to turning inside a Spitfire was as simple as continuing the turn once the flaps were deployed, why didn't the Germans teach their pilots to do this?
Presumably they didn't or the spits would have been shot out of the sky by 109s that now turn faster, go faster, dive faster and accelerate faster piloted by pilots who knew how to beat the Spit in a turn, which was until now its main advantage

A personal view is that the planes were well matched. An experienced 109 pilot would have an advantage over an inexperienced Spit pilot. In the same was an experienced Spit pilot would have an advantage over an inexperienced 109 pilot.
The experienced pilot of either aircraft will always get that extra out of the plane they are flying. That I suggest is why Aces could get their 109 to do things (in this case turn) better than an inexperienced Spit pilot, or indeed an inexperienced 109 pilot.

I can only repeat what I said earlier. I never heard or read about any RAF pilot who felt at a disadvantage against a 109F when flying a Spitfire V. Against the 190 the RAF knew who was the hunted, but not when against the 109F.
At the end of the day it was the experience of the average pilot when in the air that is the deciding factor. If your average Pilot in your normal plane is better than the other side then you will dominate the air (hint at the 190). If they are well matched then no one will dominate (hint at the 109F).

Soren · Dec 15, 2006

Hop,

If they weren't there there'd be no increase in AoA or lift - its that simple.

Ofcourse you can run circles around that it isn't the slats themselves which create lift all day if you want, but thats of no concern to me.

And about the tests you've seen, well what other tests besides the British ones have you seen exactly ??

And about the Russian 109G-2, well IIRC the gun-pods were never removed. And the Friedrich they tested had no covers for the main gear, creating alot of interference drag.

Yes, it does. The bigger the wing (at a given weight, ie the lower the wingloading) the lower the induced drag, because induced drag is proportional to the square of CL. Basically, a smaller wing has to pull a higher AoA to generate the same lift as a larger one, which means higher induced drag.

Nope your "big wing" theory is still wrong. A bigger wing does not have less induced drag than a smaller one.

Also here's how you figure out Cdi (Induced drag);
(Cl^2) / (pi * AR * e)

As you can see 'e' (Oswald efficiency factor) and AR (Aspect Ratio) are two very important factors you just missed - its not just the square of CL as you claim.

And as to induced drag in turns, take a look at the span-loadings.

Jabberwocky · Dec 15, 2006

109F4 pilots shot down over all Malta said essentially the same thing in their debfiefs (to paraphrase):

"The Messerchmitt is faster, while the Spitfire is more manouverable"

Note that manouverability is not just turn radius, but other factors like rate of roll, initial turn, pull outs (elevator authority) ect.

This seems to be the rule of thumb for the Mk V vs the 109F. Spitfire is slower but better at manouvering.

Glider · Dec 15, 2006

Jabberwocky said:
109F4 pilots shot down over all Malta said essentially the same thing in their debfiefs (to paraphrase):

"The Messerchmitt is faster, while the Spitfire is more manouverable"

Note that manouverability is not just turn radius, but other factors like rate of roll, initial turn, pull outs (elevator authority) ect.

This seems to be the rule of thumb for the Mk V vs the 109F. Spitfire is slower but better at manouvering.

That I agree with.

Soren · Dec 15, 2006

Be careful with pilot accounts, Spitfire pilots shot down or having experienced dire situations said similar things I'm sure - like Pierre Closterman.

At high speeds the Spitfire, by virtue of its better elevator authority, was easier and less tiring to control in a turn. Roll rate was the same or slightly better for the 109.

Chingachgook · Dec 15, 2006

Soren · Dec 16, 2006

The single German test you mean. And go ahead and believe it blindly if you like, still doesn't change reality though.

mad_max · Dec 17, 2006

chingachgoo,

As you see the biased ones posting on boards are perfectly fine with accepting
1 German test, data sheet. Etc. to prove how exceptional the German tools of war
were.

But anything having to do with Allied tools of war they need atleast 3 sources from
3 different departments of the war departments.

Soren · Dec 17, 2006

Udet · Dec 18, 2006

I am proceeding to quote this piece of jewelry:

"As you see the biased ones posting on boards are perfectly fine with accepting
1 German test, data sheet. Etc. to prove how exceptional the German tools of war
were.

But anything having to do with Allied tools of war they need atleast 3 sources from 3 different departments of the war departments".

Nice try Mister, but refrain from twisting the issue. Since the very end of the war it has been allied testings that have become "the truth". Forgers of "the truth" include "serious researchers" such as the individual known as "Kit" Carson, or Mike Williams...and not just that, even guys who have not researched at all but enjoy unleashing the tongue -Chuck Yeager- have made a substantial contribution to forge the truth.

On the other hand, anything that might suggest German hardware surpassed allied toys should be subjected to "closer scrutiny", if not discarded off-hand.

So..."biased ones" huh? Very, very funny.

Brain32 · Dec 18, 2006

Hop provided good turn time numbers for the G2, I have these numbers also:
109F4: 19,6 - 20,5
109G2(normal): 20 - 21,5
109G2(normal Finnish test): 22(360kmh, 3G, 70deg bank angle)
109G2(gunpods): 22,6-22,8(pretty neat isn't it )

SpitfireMkVb: 18,8sec
SpitfireMkIX: 18,5sec
Now about turnfight of theese planes, what most people really completely fail to realize is the fact(ask a real pilot) that making a sustained turn in ANY plane(let alone in a high powered warbird in a combat conditions when people want to re-decorate your cockpit interiour with pieces of your brain) is very hard thing to do. What we have in numbers above and if we take the difficulty of the task into account, the performance difference leaves this to pilot skill only.
Forget about simulations we are talking RL here, and if you think fighting German planes in Allied planes was a walk in the park, you are not only delusional but you are also insulting your veterans

Soren · Dec 18, 2006

The Finnish test shows that 3G could be sustained for as long as their was fuel without loosing height at 360 km/h. The Russian F-4 was running at Steig u. Kampfleistung IIRC, and had previously damaged the wing quite severely having to undergo a rebuild.

twoeagles · Dec 18, 2006

Here's a chart from one of my old books from Navy flight school. It's valid
for ANY aircraft given that the altitude is being held constant and it is in a
coordinated turn. You can use it to back out some parameters of a turn,
plenty of which are in this thread.

DerAdlerIstGelandet · Dec 18, 2006

mad_max said:
chingachgoo,

As you see the biased ones posting on boards are perfectly fine with accepting
1 German test, data sheet. Etc. to prove how exceptional the German tools of war
were.

But anything having to do with Allied tools of war they need atleast 3 sources from
3 different departments of the war departments.

I am staying out of this arguement because I personally think that it is foolish to argue over these 2 aircraft. They were well matched, each had its own advantages over the other and also had disadvantages over the other.

Having said that, they were both great aircraft.

Having said that, The guys who are biased toward the allied aircraft, do the same as you say about the guys biased to the German aircraft.

Glider · Dec 18, 2006

DerAdlerIstGelandet said:
I am staying out of this arguement because I personally think that it is foolish to argue over these 2 aircraft. They were well matched, each had its own advantages over the other and also had disadvantages over the other.

Having said that, they were both great aircraft.

Having said that, The guys who are biased toward the allied aircraft, do the same as you say about the guys biased to the German aircraft.

Seconded

DerAdlerIstGelandet · Dec 18, 2006

Sorry Glider I had to edit the smiley in my post as well as the smiley in your quote of mine.

Chingachgook · Dec 18, 2006

the lancaster kicks ass · Dec 18, 2006

the -109 series and spits were in constant competition during the war, no aircraft had an advantage for more than a couple of months before some new mark or varient changed the balance so it's not until later in the war you can make general comments like that, by which point the spit is generally considdered the better combat aircraft..........

Soren · Dec 18, 2006

Chingachgook said:
Because the evidence shows that the Spit turned tighter does not change my belief.

It shows your narrowmindness, cause there's no such evidence.

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