Best Messerschmitt Bf109 subtype (1 Viewer)

[Kurfürst]

1,42ata was finally cleared in October 1943. There`s clear indication that it was cleared before, in November 1942, and June 1943, but was probably recalled in those two earlier instances.

As for 1.3ata for the G-2 (and G-6) until the automn of 1943, I wouldn`t say it was that much of a disadvantage - especially the G-2 had excellent performance anyway..

 

[Soren]

The K-4 because it was more aerodynamically clean than the previous versions and boasted an unrivalled climb rate of some 5,000 + ft/min and turned better than the latest Spitfire.

Pretty awesome with a 645 km/h cruising speed as-well.

 

[flojo]

The K-4 because it was more aerodynamically clean than the previous versions and boasted an unrivalled climb rate of some 5,000 + ft/min and turned better than the latest Spitfire.

Pretty awesome with a 645 km/h cruising speed as-well.

What is the source of the information that the K4 turned better than the latest Spitfires. Was any K4 tested against Mk14 or MK21 at the end or after the war?

 

[Soren]

The source is aerodynamics flojo.

When it comes to turn performance there are a number of very important factors to consider:

1.) The weight size of the aircraft
2.) The Clmax of the wing
3.) The Aspect ratio of the wing (The e-factor needs to be taking into consideration for better accuracy)
4.) The power available
5.) The Cd value of the a/c ( Cd = Cd0 + Cdi)

 

[Hunter368]

The K-4 because it was more aerodynamically clean than the previous versions and boasted an unrivalled climb rate of some 5,000 + ft/min and turned better than the latest Spitfire.

Pretty awesome with a 645 km/h cruising speed as-well.

At what speed could it out turn a Spitfire ? At what height is that at?

 

[drgondog]

The source is aerodynamics flojo.

When it comes to turn performance there are a number of very important factors to consider:

1.) The weight size of the aircraft
2.) The Clmax of the wing
3.) The Aspect ratio of the wing (The e-factor needs to be taking into consideration for better accuracy)
4.) The power available
5.) The Cd value of the a/c ( Cd = Cd0 + Cdi)

You didn't present 'sources', Soren.

You present several calculation factors, but you don't present all the ones desirable to ATTEMPT to model relative turn performance.

There are 'opinions' based on standard aircraft 'rules' of thumb to predict a rough estimate of performance.

You are expressing an opinion not based on an unimpeachable model, not tested, not tested under controlled conditions and not verified.

You have left out several 'model' factors that are also important such as the more efficient load distribution of the elliptical wing, the stiffness of the wing, the static stick free margins with respect to stability, the effectiveness of the rudder, the relative aerodynamics - particulary at near separation angles of attack - for flow over rudder and elevator, the control forces required to sustain a high speed/High G turn..., the relative stability in pitch and yaw for large asymetric loads,

The relative Drag comparisons to help estimate the energy 'bleed' at different flight envelopes.

etc, etc.

Do you have all those factors at hand and could you actually use them to prove your thesis?

You are entitled to your opinion, but he asked you a polite question about sources and you blew it off with your standard Aerodynamics mantra.

I am pretty sure you can not... anymore than I could disprove your statement. I don't have all the data necessary to attempt a sophisticated model for either aircraft. The primary difference is that I know what I don't know.

It is a lot tougher to a.) model asymetric flight conditions, and b.) have them match closely with controlled tests.

Why don't you answer a question like that with some opinions based on fact, acknowledge facts you don't know which could alter your opinion - and leave it as an Opinion?

 

[DerAdlerIstGelandet]

The source is aerodynamics flojo.

When it comes to turn performance there are a number of very important factors to consider:

1.) The weight size of the aircraft
2.) The Clmax of the wing
3.) The Aspect ratio of the wing (The e-factor needs to be taking into consideration for better accuracy)
4.) The power available
5.) The Cd value of the a/c ( Cd = Cd0 + Cdi)

Then let us see it by a reputable source.

 

[claidemore]

Would love to see the figures that 'prove' that turn superiority.


Climb rate was definately not unrivalled, we proved conclusively that the Mk IX and Mk XIV outclimbed 109K4's in another thread. Only one existing test performance chart shows climb rate of just under 25m/s (4900 ft/min) with 1.98ata and MW50 (which 'may' have seen limited operational service with a combat trial unit), and Mk XIV charts show regular 'operational' planes exceeding that rate. There was also at least two squadron of operational Mk IXs with 25lb boost that had climb rates in the neighborhood of +5700 ft/min in May of 1944.

The K4 was definately the best climbing 109, and also the fastest climbing axis fighter, but it was not unrivalled by its opponents.

 

[Lucky13]

I don't know squat about the Bf 109 and its sub variants as such. But, I have always had a soft spot for the F and G variants...so I'm gonna read more of the discussion before voting....
Best sub variant of the Bf 109? Wouldn't each variant of the 109 be the best one in its respective period of time?

 

[Soren]

You didn't present 'sources', Soren.

You present several calculation factors, but you don't present all the ones desirable to ATTEMPT to model relative turn performance.

There are 'opinions' based on standard aircraft 'rules' of thumb to predict a rough estimate of performance.

You are expressing an opinion not based on an unimpeachable model, not tested, not tested under controlled conditions and not verified.

You have left out several 'model' factors that are also important such as the more efficient load distribution of the elliptical wing, the stiffness of the wing, the static stick free margins with respect to stability, the effectiveness of the rudder, the relative aerodynamics - particulary at near separation angles of attack - for flow over rudder and elevator, the control forces required to sustain a high speed/High G turn..., the relative stability in pitch and yaw for large asymetric loads,

The relative Drag comparisons to help estimate the energy 'bleed' at different flight envelopes.

etc, etc.

Do you have all those factors at hand and could you actually use them to prove your thesis?

You are entitled to your opinion, but he asked you a polite question about sources and you blew it off with your standard Aerodynamics mantra.

I am pretty sure you can not... anymore than I could disprove your statement. I don't have all the data necessary to attempt a sophisticated model for either aircraft. The primary difference is that I know what I don't know.

It is a lot tougher to a.) model asymetric flight conditions, and b.) have them match closely with controlled tests.

Why don't you answer a question like that with some opinions based on fact, acknowledge facts you don't know which could alter your opinion - and leave it as an Opinion?

Errr, Bill this isn't just some "rule of thumb" presentation, we can quite easily calculate the capability of these fighters in the horizontal if we have the following figures from windtunnel data: Cd0, Clmax and thrust by prop at specific engine output. We know the weight and dimensions so the rest is easy.

Remember we're not trying to predict stability, stall angle or anything in that spectrum.

We're not designing a new a/c here Bill, we have the data we need from windtunnel tests. Don't make it harder than it is

 

[Soren]

Climb rate was definately not unrivalled, we proved conclusively that the Mk IX and Mk XIV outclimbed 109K4's in another thread. Only one existing test performance chart shows climb rate of just under 25m/s (4900 ft/min) with 1.98ata and MW50 (which 'may' have seen limited operational service with a combat trial unit),

Claidemore that performance chart was an estimate with a thinner prop which increased speed but also decreased climb rate, plus rads were assumed open. Climb rate with rads closed and with the std. prop were no doubt in the 5,000 + ft/min area.

 

[claidemore]

Soren:

Maybe, but the K4 @1.8 ata (with the production prop?) climbs at 4035 ft/min, so boosting it to 1.98 is unlikely to jump it past 5000 ft/min, IMO.

Spitfire tests were done with open rads as well, they had automatic rad flaps without manual override so the comparison is a fair one.

Climb rates for Mk XIV at 21 lbs or 25 lbs boost would also be MUCH higher than 5000 ft/min. It's just no contest in the climbing department against the late marks of Spitfire.

I can offer a couple simple figures in the turn debate. Assuming the oft quoted clmax of 1.7 for the 109, stall speed @ sea level would be 100mph. The MkXIV stall speed according to the pilot notes is 85 mph. An obvious turn advantage at max turn rate hovering just above the stall.

In a higher speed sustained turn, the Mk XIV with 25lbs boost producing better than 2400 hp at low alt, with a much lower wingloading than the K4, would again have a significant advantage.

 

[kool kitty89]

Wingloading isn't lift loading... You need to consider CL, and the CL of the 109's airfoil is a bit higher than the Spit's and the LE slats add another ~25% to CLmax. Sot the Spit would have to have well over 25% lower wing loading to have an advantage. (closer to 35% lower)

But the Spit's eliptical wing did offer a good lift to drag ratio.

 

[drgondog]

Errr, Bill this isn't just some "rule of thumb" presentation, we can quite easily calculate the capability of these fighters in the horizontal if we have the following figures from windtunnel data: Cd0, Clmax and thrust by prop at specific engine output. We know the weight and dimensions so the rest is easy.

Soren, 'easy'for you often translates into 'wrong'. Aircraft have different stability characteristics in high G loading... e.g. Nobody predicted viloent snap roll stall conditions in low speed high G turn for an Fw 190 because aerolasticity was not a well understood science. At stall in a high G turn the predictions of boundary layer separation within several degrees may become an exercise in Chaos Theory.. CL degradation in a statistical context can be huge if a 3 degree window.

Remember we're not trying to predict stability, stall angle or anything in that spectrum.

You don't bother because it isn't important to you and you don't really understand the interactions between a flexible airframe, asymetric loading, directional stability in that arena but you make blanket statements like you can quote a recipe for cupcakes.. you didn't even understand the Lednicer report Soren but you are trying to BS your way into being 'acknowledged' as someone who understands Aero.

We're not designing a new a/c here Bill, we have the data we need from windtunnel tests. Don't make it harder than it is

Don't make it easier than it is. Start producing facts and sources.

 

[drgondog]

Wingloading isn't lift loading... You need to consider CL, and the CL of the 109's airfoil is a bit higher than the Spit's and the LE slats add another ~25% to CLmax. Sot the Spit would have to have well over 25% lower wing loading to have an advantage. (closer to 35% lower)

But the Spit's eliptical wing did offer a good lift to drag ratio.

The lift distribution for the Spit/P-47 eliptical wing planform was superior to the Mustang/Fw 190 and Me 109 trapezoidal plan form..

This (theoretically and realistically) gave the Spit an imprecise advantage over a similar CL in either a 51 or 190 or a 109 for same aspect ratio and CLmax. The real question is 'how much' - also more efficient in induced drag - but nobody on this forum can answer that question - at least he/she has not made him/her self known.

 

[claidemore]

Wingloading isn't lift loading... You need to consider CL, and the CL of the 109's airfoil is a bit higher than the Spit's and the LE slats add another ~25% to CLmax. Sot the Spit would have to have well over 25% lower wing loading to have an advantage. (closer to 35% lower)

But the Spit's eliptical wing did offer a good lift to drag ratio.

Like I said, I can only offer simple figures. Wingloading is considered a good general indicator of turn performance, generally speaking lower wingloading = better turn performance, all other factors being equal.

Simple don't always mean wrong.

Wingloading of the MkXIV was 35.1 lbs/sq ft, 30.7 for the Mk IX and 43.4 lbs/sq ft for the 109K4. That's a 21% advantage for Mk XIV and 29% advantage for Mk IX.

As I mentioned, the 109 wing is often quoted as having a clmax of 1.7 with slats deployed and possibly with combat flaps deployed. (The RAE tests seem to indicate that their clmax calculations were with both slats and combat flaps.) Without slats, it is assumed to be 1.4. The slats therefore only give an 18% increase in cl.

The Spitfire MK IX is generally given a clmax of 1.6, a figure which my calculations support. In my calculations for the Mk XIV with stall speed of 85 mph (as indicated in the pilots notes) and weight of 8500 lbs I get a clmax of 1.9.

 

[kool kitty89]

Okay, I don't remember the Spit's CL being anywhere near that high (in the 1.34 region is what I remember) that would change things alot. This isn't with flaps is it? And did the Spit ever even get a combat/maneuvering setting for the flaps?

 

[DerAdlerIstGelandet]

Still waiting on a reputable source...

 

[Kurfürst]

Would love to see the figures that 'prove' that turn superiority.

I think an educated guess can be made using assumed values of drag, Oswald effiency etc. Then these can be applied to different altitudes.

Climb rate was definately not unrivalled, we proved conclusively that the Mk IX and Mk XIV outclimbed 109K4's in another thread.

I don`t think so.

Only one existing test performance chart shows climb rate of just under 25m/s (4900 ft/min) with 1.98ata and MW50 (which 'may' have seen limited operational service with a combat trial unit), and Mk XIV charts show regular 'operational' planes exceeding that rate.

I would like to see that Mk XIV climb chart. I doubt it even exists.

There was also at least two squadron of operational Mk IXs with 25lb boost that had climb rates in the neighborhood of +5700 ft/min in May of 1944.

The figures you are using are referring to climb test done with a Mk IX missing ca. 300 lbs takeoff weight. Of course it climbs faster.

Remove 300 lbs from any plane, and it will climb faster, too.

The K4 was definately the best climbing 109, and also the fastest climbing axis fighter, but it was not unrivalled by its opponents.

I`d say the fastest climbing 109 was the G-10 at 1.98ata.
The fastest climbing Axis fighter would be the Me 163, though, I don`t think there`s much comparison with... what, 160 m/sec IIRC?

Climb rates for Mk XIV at 21 lbs or 25 lbs boost would also be MUCH higher than 5000 ft/min. It's just no contest in the climbing department against the late marks of Spitfire.
...
In a higher speed sustained turn, the Mk XIV with 25lbs boost producing better than 2400 hp at low alt, with a much lower wingloading than the K4, would again have a significant advantage.

It is a pity that +25 lbs was never cleared or used by the Griffon engined XIV operationally. I think it was tested once, and the engine immidiately failed. I haven`t seen conclusive evidence to the use +21 lbs operationally either, apart from anti-diver missions, though it was proposed for the 2nd TAF in late 1944, obviously for anti fighter use.

Of course in the real world these comparisons meant little, given how rare the XIVs were.

 

[parsifal]

I am no expert in this, but I am surprised someone is claiming the 109 to have better turn characteristics over a spitfire.

I will admit i dont understand the science, but isnt the wing area going to alter the the force vector from one direction to another, more quickly if you have a large wing. One would think that a large wing results in a larger moment of force, and hence a quicker effect on the current force vector. 109 and spitfire are similar weighted aircraft, but the spit , I believe, has a much greater wing area than the 109 (doesnt it???). Isnt it sort of like a sail, a big sail, set in a diffferent direction, is going to move you off in that direction more quickly, than say a smaller sail for a vessel of similar weight.

I am genuinely confused. Would any of you gentleman please like to try and explain. And i dont want to be browbeaten please, just wanting the basic theory, and results of that theory