Best Messerschmitt Bf109 subtype

[Soren]

IF the 109E stalled in level flight, engine off, at 74mph, the Cl would be 2.32, which is ridiculously high. At 84mph for the 109K4 the CL would be 2.4, an even higher number! Sorry, but those numbers just don't fly. (pardon the pun)

Ha! They certainly fly better than the 2.32 Clmax for the Spitfire !!

PS: As already explained a Clmax of 2+ isn't unormal at landing speeds as the prop accelerated air much faster over the wing than freestream leading the Cl estimation to be higher.

Therefore, I repeat, we can't use stalling speeds as a reference here as it depends on two factors, 1) the Clmax freestream 2) the thrust provided by the prop. Thus you need the freestream figures for comparisons, and as explained the Clmax for the different a/c are as follows:

Bf-109F/G K: 1.70
Ta-152H: 1.62
FW-190: 1.58
P-51: 1.35 (According to NACA)
Spitfire: 1.36

 

[Udet]

Whatever the turn rate of any Spitfire version might have been, German fighter pilots feasted with the almighty Spit.

Ask RAF for Spitfire losses for 1941, 1942 and the first of months of 1943 [pre-8th Air Force assembly era], when a gross slaughter of British pilots took place.

 

[claidemore]

I can 'prove' your CL figure for the 190 as being correct, but the same formula does not 'prove' the 1.36 for the Spitfire. Sorry, but that number is incorrect.

Even the clipped wing Spitfire IX/XVI had a CL of 1.5.

I've seen that 1.36 number on a gaming forum, tested the formula that was supposedly used to get it and it didn't work.

As for stall speed, it is arguably the most important factor in max turn rate, particularly in combat situations. We have to use it as a reference. It is also one of the numbers we must have to calculate CL, and one of the numbers we can calculate if we already have CL. Thus, knowing the CL of the 109 as being 1.7, we can calculate stall speeds that are in all cases higher than those you have indicated for 109s, in the case of the 3400 kg 109K4 the stall speed is 100 mph.

 

[Soren]

I can 'prove' your CL figure for the 190 as being correct

You can ? please do then cause I know the true stall of the Fw190 and it aint the one in the RAE report, that bird as already noted suffered from ill adjusted ailerons.

 

[Soren]

I can 'prove' your CL figure for the 190 as being correct, but the same formula does not 'prove' the 1.36 for the Spitfire. Sorry, but that number is incorrect.

Even the clipped wing Spitfire IX/XVI had a CL of 1.5.

I've seen that 1.36 number on a gaming forum, tested the formula that was supposedly used to get it and it didn't work.

As for stall speed, it is arguably the most important factor in max turn rate, particularly in combat situations. We have to use it as a reference. It is also one of the numbers we must have to calculate CL, and one of the numbers we can calculate if we already have CL. Thus, knowing the CL of the 109 as being 1.7, we can calculate stall speeds that are in all cases higher than those you have indicated for 109s, in the case of the 3400 kg 109K4 the stall speed is 100 mph.

Wrong wrong wrong and wrong.

The Bf-109 K-4 has a landing speed (Which is always a good deal higher than stall speed for obvious reasons) of 150 km/h for crying out loud!! 10 km/h below the speed you're wanting it to be stalling at !!

Do you want NACA's own papers on the Spitfire to show the Clmax of the Spitfire's wing ?? Ok, attached below it is.. The Clmax was establised as 1.18 to 1.15. There you go. So shall we use these figures or the British results of 1.36 ??

In short the only one suffering from wishful thinking is you Claidemore.

 

[kool kitty89]

If you use the true CL directly to determine stall speed, you'll get the stall speed in engine off condition (dead stick/ gliding) but as Soren said the prop wash adds considerable lift due to the higher speed of airflow. Engine at idle should give similar figures, though still very slightly skewed. (some added airflow will still be present, but not very significant; basicly negligable)

This is also why twin engine a/c ("twin slipstream) tend to turn better than single engine craft of similar configuration. Also why jets (and pusher props) stall a bit differently and why the taildragger configuration didn't work on the Me 262.

 

[Hunter368]

Good information KK

 

[claidemore]

The American test used an unreliable method of measuring stall speeds, hence the low CL figures they recorded. RAE used a trailing static head (very difficult in a single seat fighter and seldom done) to get much more accurate results on both the Spitfire and the 109. This alone gives the RAE tests of the 109 considerable value as far as stall and CL go.

RAE did record 1.36 CL in a glide, but 1.89 power on. This corresponds to the 1.95 they got for the 109 power on. Only a 4% difference. Basically, the slats on the small 109 wing only increased it's CL to slightly ahead of the Spitfires broad elliptical wing, not enough to overcome the 109s initial inferior wingloading, consequently the Spit always had a tighter turn, as recorded in tactical trials by both sides.

This did not change with the K4. It was an improved plane, not a completely redesigned one.

When I say 'prove', i mean using an equation to prove a number mathmatically, ie doing a calculation in reverse to make sure you get the number you started out with, I'm not using the word in a "I'll show you' context. Stall speed for FW 190 at 1.58 CL is 110 mph (P51B is 100 I believe?). Some sources give stall speeds as high as 127 mph for the 190, so 110 is pretty generous, though being generous in these discussions seems unpopular and possibly unwise. But then I'm not trying to change history, just trying to prove what has always been held to be true.

All the landing speed minimums I've seen for 109s are 180 kmh, thats gear and flaps down. Might hit 150 just as the pilot pulls the plane into a 3 pt attitude and touches down but doing approach speed at 150? Cripes, thats the approach speed of a Hurricane! You're not going to tell me the 109K4 could turn with a Hurricane are you?

On the Mk XIV, landing speed is 100 mph, clean stall speed is 85, 15 mph less. (incidently, they recomended landing 20mph faster for safety)

Knock 20 kmh off the 180kmh for 109 approach speed, and you get 160kmh for clean stall, a similar ratio as in the Mk XIV Spit example above. So I don't see anything wrong with my calculated stall of the K4 at 100mph. If there is an historical document that says otherwise, I'd love to stand corrected.

Other factors not included in a simple CL/stall calculation might put me out by a few kmh for that stall speed, but definately not in the 134 kmh area that you maintain.

Once again, that is the stall speed of a Hurricane! The Hurri and Spit were very close in turn rate, so if the 109 was turning circles around the Spit, was it kickin the Hurris butt too? I haven't seen anybody trying to prove that one...yet.

At the end of the day, despite haggling over CL and stall speeds, we still don't have any historical test or trial that gives any 109 model a better turn performance than any Spitfire. We do have trials that show the Spitfire turning better than FW, 109, Mustang, Tempest, Typhoon etc, in fact it was used as the standard by which to measure all the others.

 

[kool kitty89]

The 127 mph stall figure for the 190 was of ther early prototype with much smaller wing area and different wing plan form, and with the original BMW 139 engine. (albeit it was lighter a/c as well)

The first prototype, the Fw 190 V1 powered by a 1,550 hp BMW 139 two-row 14-cylinder radial engine, with civil registration D-OPZE, was flown on 1 June 1939 and soon showed exceptional qualities for such a comparatively small aircraft, with excellent handling, good visibility and speed (initially around 610 km/h (380 mph)).[8] The roll rate was 162 degrees at 410 km/h (255 mph) but the aircraft had a high stall speed of 205 km/h (127 mph). According to the pilots who flew the first prototypes, its wide landing gear made takeoff and landing easier, resulting in a more versatile and safer aircraft on the ground than the Bf 109. The wings spanned 9.5 meters (31 ft 2 in) and had an area of 15 m² (161.46 ft²).

This became excessive on the heavier V5 with similar configuration to production 190A's (but not the pre-production A-0's) but initially retaining the original wing:

At first the V5 used the same wings as the first two prototypes although, to make room for the bigger undercarriage, the wheel arches were enlarged by moving forward part of the leading edge of the wing root (in this form this prototype was called the V5k for kleine fläche/small wing). The V5 first flew in the early spring of 1940.

However, the weight increase was substantial, 635 kg (1,400 pounds), leading to higher wing loading and a deterioration in handling. As a result, following a collision with a ground vehicle in August 1940 that sent the V5 back to the factory for major repairs, it was rebuilt with a new wing, with a larger area, 18.30 m² (197 ft²) and span of 10.506 m (34 ft 5in) and which was less tapered in plan than the original design (the aircraft was now called the V5g for grosse fläche/large wing). This new wing platform was to be used for all major production versions of the Fw 190.

 

[claidemore]

Footnote: the RAE tests with trailing static head to measure stall and CLmax, gave a figure of 1.36 in a glide for the Spit 1, and 1.4 in a glide for the 109E. Static head indicated a speed at the stall for the 109 of 95.5 mph, cockpit instrument IAS was 75. This was with slats open, and they noted that both slats opened up simultaneously.

So comparing a cl of 1.7 for the 109 to 1.36 of the Spit, is comparing apples to oranges, the actual comparison derived using the same equipment under the same test conditions, is 1.36 to 1.4.

Or full throttle, 1.87 to 1.95.

 

[Soren]

Claidemore are you seriously trying to suggest that the Clmax of the 109's wing without slats was below the Spitfire's ?? This is as far out as your claim that the Clmax for the Spitfire's wing is 1.50!

Don't you understand that the Spitfire's wing Clmax was as low as proven because it was thin and used a rather low Clmax airfoil ??? (NACA 2200 series)The Bf-109's wing is thicker and uses a higher lift airfoil (NACA 2R1)!

Moving on..

The Emil the RAE tested was first of all not using proper fuel, so power wasn't high enough, and secondly the stalling figures are completely off so something wasn't done right, go read the 109E's POH and you'll see that right away.

Furthermore the V24, a 109F with a reduced wing span and wing area of 15.1m^2 because of removed wing tips achieved a Clmax of 1.48 (Freestream) in windtunnel tests, and this was WITHOUT slats and with a lower AR wing. So the Clmax WITHOUT slats for a full span wing was somewhere in the area of 1.55.

Here's the effect slats flaps have on the Clmax of a std. 12% Clark Y airfoil (Note: The NACA 2R1 is a modified Clark Y airfoil with a higher Clmax and lower drag)

So are you still under the illusion that the slats only helped a few percent ?

As for landing speeds, here are the landing speeds for the Bf-109F-4 and K-4:

Bf-109F-4 V-lande: 135 km/h
Bf-109K-4 V-lande: 150 km/h

These are the official landing speeds, in TAS! Not IAS!

And the Clmax and Cd0 of the 109F gear and flaps up:

By Comparison the Ta-152H-1 has a landing speed of 155 km/h and the Fw-190 D-9 one of 167 km/h and the P-51D one of 170 km/h.

Do you need further proof ??

Oh and guess what the Bf-109 also has a much shorter take off roll than the Spitfire. Do you see the pattern emerging ??

 

[claidemore]

I am seriously suggesting that clMax in a power off glide (slats OUT)for a 109E is 1.4 and clMax for a Spitfire Mk 1 is 1.36. This is straight from the RAE test chart. I don't see how we can get a more accurate comparison than two tests done by the same organization at the same time. Other data may indicate different results, but for purposes of comparison, the RAE test is ideal.

As usual, those who find that those numbers do not support what they want to believe, will claim that the British didn't know what they were doing, so the test must be wrong or biased or something. Sometimes the grapes are sour.

I fail to see how the type of fuel can affect a 'power off' glide?

Actually the 109 wing resembles the NACA 2315 and 2310. The slats helped the 173 sq ft 109 wing, by a factor of about 12-13% as you alluded earlier, HOWEVER they only increase it's cl compared to the 242 sq ft Spit wing, by 3%. That is not hard to understand.

20 degree flap setting and 150 more horsepower, 500 lbs less weight, the 109 should have a shorter take off roll, particularly if the Spit does not have a constant speed prop. With constant speed prop the Spit roll off was only 150 yards (for the heavier Mk II!).

We still have trials done by Rechlin and RAE and AFDU that show the Spitfire outturning the 109. Can all those trials be wrong?

 

[kool kitty89]

Soren, something I noticed from the Drag Estimation chart, the automatic "slot" increases the CLmax by ~42.6% not 25%, so using that figure for the 109's ~48% span LE slats the CLmax should increase by ~20.4%.

And if you work backwards (using all figures according to claidmore's post) with 1.4 CLmax with slats adding 13%, w/out slats the wing's CL would be ~1.24 (which is worse than the standard Clark Y airfoil), which is decidedly low. And if we use other figures it's even lower.

Even if we assume the wing is a standard (less efficient) Clark Y airfoil from that chart with 48% span slats, the CLmax with slats should be in the area of 1.67. (using data from the Drag Estimation chart) possibly a little less since the inner wing may be past critical AoA. (not sure on that)

 

[claidemore]

The stalling speeds of the 109E are as stated 74 mph flaps and gear up, and 61 mph gear flaps down, and this is from the Dash 1 (POH).

This is in very close agreement with the RAE tests of the 109E, which got a stall speed reading of 75 mph for flaps and gear up (ASI air speed indicated, which we usually refer to as IAS nowadays) on the regular airspeed indicator in the cockpit, and 61mph for flaps and gear down. Of course the real speed, (TAS) as measured by the 60 ft trailing static head, was 95.5 mph for flaps and gear up, with slats deployed.

That gives us a clmax of 1.4 but more importantly, it gives us an accurate stall speed, which is 11.5 mph higher then the stall speed of the Spitfire measured using the exact same method. And there lies the turn advantage for the Spitfire, the 109 stalls first, and the Spit is still turning.

The guys who flew these planes have been telling us this for nearly 70 years, but we're just too smart and arrogant to believe them.

 

[Soren]

The guys who flew these planes have been telling us this for nearly 70 years, but we're just too smart and arrogant to believe them.

I beg your pardon ?? Are you forgetting that just as many has said otherwise and most notably so the experts flying the a/c such a LW chief test pilot Heinrich Beauvais ??

I think it is arrogance to refuse to want to learn the truth and desperately cling to old claims myths, refusing to use ones logic,

Claidemore,

You're Cl estimations are to put it simply very inaccurate, heck take a peak at the normal Clmax of a std. 12% Clark Y airfoil and then remember that the Bf-109's wing used an improved higher lift Clark Y airfoil designated NACA 2R1 which Clmax range is close to that of the 23000 series. And with a TR which ranged 14.2% at the roots to 11.35% at the tips, the 109's wing is alos thicker. By now use of pure logic will tell you that the Clmax can only then be significantly higher, esp. when adding the approx. increase in Cl offered by the slats, which is atleast in the 25% range in the covered areas.

As for the RAE tests, no they can't have been very accurate for the very reason that everyone, including the French, Finnish Germans got completely different results from actual windtunnel tests which mind you are allot more accurate than those RAE field tests. Remember that in a windtunnel you are in complete control of the inviroment, while out in nature a large magnitude of things could effect the way the tests come out.

KK,

The Handley page auto slots represented on that chart are of a different design than the ones on the 109, as they drop down to increase camber. The fixed slot is of the same design as the 109's auto slats when they're fully deployed and this is therefore the one to be looking at. The increase is in this case from 1.29 to 1.77, a 37% increase in Clmax, but this is only in the covered area, so we can cut that down to 17% and then down to around 13% when we factor in that the 109's wing was thicker to begin with.

 

[claidemore]

Soren;
Rechlin test: Spitfire outturns 109 in every situation.
RAE tests, Spitfire has smaller turn radius, Spitfire stalls at a higher G load, Spitfire stalls at a lower air speed, measured TAS stall speeds of 95.5/109 and 84/Spit I.
AFDU tactical trials: Spitfire out turns 109, 190, and every thing else.

Would this be the source of the myth?

Logic somehow ignores all these tests and all the data contained in them, and assumes that the 109 wing which has "improved higher lift" has cl that is "significantly higher" and has an "approx. increase in Cl" with cl range " close to that of the 23000 series" and 2%? higher TR has somehow overcome a 30% deficiency in wing area, and a 21% deficiency in wingloading.
So we take some assumptions, a handful of generalizations, and use logic to come up with what?

The Hawker Typhoon had a nice thick wing,(NACA 23 series) and it didn't turn as well as the Spitfire either. Interesting that it has a similar trapezoidal profile to the 109 and 190 which caused it to get shot down by over-enthusiastic Mustang pilots. Could that trapezoidal shape be the source of its poor turn performance?

Quote from Mike Williams site:

The Tempest arose from Hawker's desire to apply a new, thin wing to the Typhoon in order to enhance performance. The Tempest V combined the new semi-elliptical wing with the Typhoon airframe and Sabre II engine. The new wing was five inches thinner at the root with the maximum depth of the new section occurring farther back, at 37.5% of the chord, while the thickness/chord ratio was reduced, 14.5% at the root tapering to 10% at the tip.

Hmmm, those numbers are pretty close to the 109 numbers, how did the Tempest fair in a turn fight against a Spitfire? Not well. Mustang outturned it too, and it was just slightly better than the 109G2. Since I think the G2 used in those trials was not up to snuff, I'll allow that it might have matched or even outturned the Tempest slightly if it was in 100% condition. (i know that will come back to haunt me!)
In any case, we know that the Spitfire easily outturned the Tempest, and the Tempest turned about the same as a 109, so logic tells us?


As for my cl calculations, they are completely accurate.
Stall speed of 95mph TAS, weight of 5600 lbs, wing area of 173 sq ft and you get cl of 1.4020.

 

[Soren]

Claidemore,

We've already discussed why the tests with the Emil aren't worth anything many times before so I wont even go there.

As for the stalling speeds of the Bf-109E that I listed, these are TRUE airspeeds, NOT indicated stall speeds. The indicated stalling speed was 10 km/h lower in all cases.

As for the Clmax of the wing, it is 1.70 as established in multiple windtunnel tests clean with gear flaps up. With no slats the Clmax would've been around 1.50+.

The Spitfire's wing's Clmax was 1.36.

And here the Clmax of the NACA 23000 series airfoil from 9 to 18% in thickness ratio. As you can see there's a limit to how thick the wing can be before Clmax start to drop instead of increasing:

The average Clmax for a airfoil from 15 to 09% is 1.58 to 1.59, much higher than normal, which can also been seen when compared to the Clmax ofthe std. Clark Y airfoil.

Btw, the Clark Y airfoil was used by all Yak, La LaGG fighters, while the 109 featured a modified type with a higher Clmax and lower drag.

And as for the Typhoon, like I said it outturned the Tempest despite being heavier, having less wing area and having less power available, and this was thanks to its higher TR AR wing.

PS: The Tempest also used a airfoil which was bad for turn performance but good for speed.

 

[kool kitty89]

He's saying that the combination of the higher lift airfoil, the higher TR, and LE slats, overcome the high wing loading.

The Typhoon should have had a fairly high CL, but it had high wing loading and no additional high lift devices.

The Tempest's wing should have had a much lower CL, due to being much thinner and using a low drag airfoil with the max thickness at 37.5% chord. (similar to the P-51's psudo-laminar-flow wing;low-lift and low drag= good speed but not for turn)


Technically the 109F and later models had a tapered wing with rounded tips, and thus would no longer be considered trapizoidal. And anyway there were other a/c with similar plan for that had decent maneuverability as well.

 

[Soren]

Very correct KK.

 

[claidemore]

RAE had people who devoted their entire lives to aircraft research, they had experienced test pilots, aeronautical engineers and designers, skilled technicians, research scientists, the best aviation people in Britain, with an enviable reputation. (they had Beatrice Shillling too!) They had access to some of the best equipment in the world, and cooperated extensively with American test facilities and personnel. Hitler wanted their research so much that he would not allow the Luftwaffe to bomb it, assuming that eventually he could capture it.

You seriously think we should completely dismiss their findings and results? All these highly qualified experts were wrong, and you are right?

Persoanlly, I think they knew a hell of a lot more about this stuff than your or I, and this chart illustrates it pretty well.