Bf-109 vs. Spitfire....

[Soren]

Any PR fighter was difficult to intercept Glider. And the Mossie was only a head ache to catch for the German Zerstöreres, the Bf-109 had no problem catching the Mossie.

[Glider]

Originally Posted by Soren

Any PR fighter was difficult to intercept Glider. And the Mossie was only a head ache to catch for the German Zerstöreres, the Bf-109 had no problem catching the Mossie.

Then why didn't they?

[Soren]

They did. Ask Erich.

[Glider]

The main question was the statement that the 109K could go faster than a Spit IX at full throttle at altitude. Now this may well be the case I truly do not know the cruise performance of the 109K hence my question ,what was the cruising speed of the 109K at what altitude.

I admit that I find it hard to believe that the 109K would cruise at over 410 mph, which you must admit is a legitimate doubt. It is interesting as Cruise speeds are strategically often more important than headline max speeds but are often harder to find out.
The best I can come up with is 366mph for the 109K but that will differ by height and definition of cruise. I believe this is a fair question and await a reply.

[claidemore]

Slower cruising speed just means you gotta get outa bed 5 min earlier to get to the fight.

[Soren]

Higher cruising speed means an energy advantage at the start of the engagement, height being the same ofcourse.

Glider,

The cruising speed of the K-4 was higher than that of earlier 109's as it was a cleaner a/c. The cruising speed of the K-4 is 645 km/h at 8.4 km according to the charts I have, which is 403.1 mph at 27,559 ft.

[Kurfürst]

Originally Posted by Glider

As a matter of interest what was the cruising speed of the 109K and at what altitude are you talking about?

Sore already answered that correcty, it would do 400 mph at ca 27500 feet. That was pretty much what the Mk IX LF would manage at 5-min WEP. The Mk IX LF`s maximum cruise speed was 328 mph, at 20000 feet, rather disappointingly slow, given the high-drag airframe.

It also pretty interesting if you think it over in the context of high speed, high altitude engagments; ie. if you think in terms of excess thrust, at 27 500 feet a Mk IX, flying at full throttle and 400 mph, has zero excess thrust for manouvering; a 109K, or a Mustang, which can achieve this speed at much lower power output than full throttle, still has hundreds of horsepower worth of excess thrust for manouvres.

In layman`s terms, they can run circles around the old Spitfire IXs at these speeds and altitudes.

Originally Posted by Glider

Just a thought but if the 109K could cruise faster than a Spitfire at max speed then why did they find it so difficult to intercept allied PR planes such as the SPit or the Mossie

For the same reason Spitfires found it hard to intercept PR 109s and He 177s over England. High flying, fast single targets the radar may not pick up in time, are difficult to vector onto and intercept.

Think about how far away a recce plane cruising at 300+ mph will get in 10-15 minutes it takes for you to climb to his altitude at 30 000 feet, while you clims at 170 mph.

Re the Zero I do find that amusing, didn't know they went over 400mph.

The point was that while the Zero was very manouverable and climbed well, it was outclassed by later US fighters like P-38, F4U etc simply because the latter were much faster and could dictate the fight.

[Glider]

Originally Posted by Kurfürst

In layman`s terms, they can run circles around the old Spitfire IXs at these speeds and altitudes.

It would be a little worrying for the Germans if they didn't have an advantage over a Spit IX

For the same reason Spitfires found it hard to intercept PR 109s and He 177s over England. High flying, fast single targets the radar may not pick up in time, are difficult to vector onto and intercept.

I admit that you have mentioned this before. I know that the He177 was used as a recce on Atlantic missions but not over the UK. Do you have any details as to these missions?
Re the 109 I understood that the Germans were unable to undertake many missions recce missions which is one of the reasons why the invasion was a success.

[Soren]

Glider,

The Germans were mislead by foney radio transmissions and mock ups situated in such a way that they believed the invasion would come further North. (Hence the stronger defences there)

[Glider]

That is of course part of the story but I do not believe that a nation such as Germany which knows knows the importance of defeating an attempted invasion succeeds, would only rely on radio intercepts.

Besides the claim is that For the same reason Spitfires found it hard to intercept PR 109s and He 177s I have not heard of the He177 being used over the UK and believe that the 109 was ineffective.
All I am asking is for something to support that statement.

[claidemore]

[quote=Kurfürst;328553]

In layman`s terms, they can run circles around the old Spitfire IXs at these speeds and altitudes.


QUOTE]

Maybe, if excess thrust was the only factor affecting turn. From everything I have read, anecdotal and official tactical trials, the Mustang could not outturn any Spit at any speed, nor could the 109 or 190A/D for that matter. Dont forget the Mustang weighs about 1000 lbs? more than a Spit IX.

From RAE Tactical Trials

Turning Circle
20. The Mustang is always out-turned by the Spitfire IX. Use of flaps on the Mustang does not appear to improve the turning circle. There is adequate warning of the high-speed stall in the form of elevator buffeting, followed by tail buffeting.

Rate of Roll
21. Although the ailerons feel light, the Mustang III cannot roll as quickly as the Spitfire IX at normal speeds. The ailerons stiffen up only slightly at high speeds and the rates of roll become the same at about 400mph.

They also note that the elevators are much heavier.


Yes the Spit IX could only do 408-415 mph level speed at alt, (and that's not at 5 min WEP either). Yet they shot down a lot of 109s and 190's.

Considered by most knowledgeable people to be the best all round fighter of WWII, and considered best by pilots who also flew Hurricanes, Mustangs, P47s, Typhoons, P40's etc. It had an ideal balance of climb, dive, maneuverability, speed and firepower. Other planes might be better at one thing or another, but the Spit IX was darn good at everything.

[Soren]

the Mustang could not outturn any Spit at any speed, nor could the 109 or 190A/D for that matter.

The Bf-109 can & did out-turn the Spitfire.

[Soren]

Glider,

Not only foney radio tranmissions, also ground mock ups of a/c, vehicles, ships etc etc.. This mislead the Germans who were using their PR a/c just the same as the British.

The British would simply let out allot of foney radio transmissions about their own forces, where they were assmbled, where they needed go and what their mission was. The Germans recieving these transmissions sent out PR a/c to check it out and thought they found the possible Allied invasion fleet. They were mock ups however..

[Kurfürst]

Originally Posted by Glider

Besides the claim is that For the same reason Spitfires found it hard to intercept PR 109s and He 177s I have not heard of the He177 being used over the UK and believe that the 109 was ineffective.

What you havent heard of and what you wish to believe has rather little substance behind it I am afraid...

Perhaps do some reading first.

[Kurfürst]

Originally Posted by claidemore

Maybe, if excess thrust was the only factor affecting turn. From everything I have read, anecdotal and official tactical trials, the Mustang could not outturn any Spit at any speed, nor could the 109 or 190A/D for that matter. Dont forget the Mustang weighs about 1000 lbs? more than a Spit IX.

Basically all manouvering is about excess thrust. Sustained turning is all about your excess thrust matching the increased decelerating force from increased drag when you are turning (and flying at a higher AoA than when in level flight, ie. higher induced drag).

So to put it into practical terms, lets see an example.

Plane A can achieve 400 mph with 1500 HP at altitude, and at this point it has 0 excess thrust (since its neither accelerating or decelerating). It can cruise at 330 mph with 1000 HP.

Plane B can achieve 440 mph at altitude with the same 1500 HP, and can achieve 400 mph when cruising using 1000 HP.

So similiarly, Plane B has 0 excess thrust at 440 mph, and has 500 HP excess thrust at 400 mph.

So when Plane A and Plane B will start turning at 400 mph, the drag experienced by both will rapidly increase, because in turn your induced drag will increase rapidly. Overall drag will increase on both aircraft, and now both would need greater thrust to sustain 400 mph in turns. Since Plane A has no more excess thrust at all, it will start to decelerate (quite rapidly) when it commences a turn at 400 mph. Plane B can use its 500 HP-worth of excess thrust to sustain its speed AND turn at the same time.

Weight of course matters, but its not so simple (the 109, for example, is much lighter than the Spit); weight actually effects how high your drag is in turn, which gets us back to excess thrust. The Spitfire has large wings for its size and weight, but at the same time its also a very draggy airframe compared to others, hence why its relatively slow, and outclassed by others at high speed turns, climbs acceleration.

Yes the Spit IX could only do 408-415 mph level speed at alt, (and that's not at 5 min WEP either).

No, the 404 mph figure for the Spitfire LFIX is at five minute WEP, at maximum output. It couldnt go faster than this, unless in dive.

Yet they shot down a lot of 109s and 190's.

Oh, it had a successfull combat record, no doubt. It would be more interesting to see though what ratios it achieved against enemy fighters, I doubt it would be all that positive, but then again it had a lot of other factors in it - relying too much on old Marks through the war, pilot experience and tactics for example.

Considered by most knowledgeable people to be the best all round fighter of WWII, and considered best by pilots who also flew Hurricanes, Mustangs, P47s, Typhoons, P40's etc. It had an ideal balance of climb, dive, maneuverability, speed and firepower. Other planes might be better at one thing or another, but the Spit IX was darn good at everything.

I have no idea who are those 'most knowledgeable people' are. It surely had good qualities, which is why it was liked so much by its pilots, and why it is widely considered a successfull WW2 fighter design. On the other hand, it had some serious defects as well. Lack of speed and range should be mentioned first and foremost, and poor control characteristics. Actually, both of the former vices can be traced back the high drag of the design. I guess the death of the lead engineer was a blow that the design team couldnt recover from.