109e vrs Spit 1

[Urchin]

Originally posted by Kweassa
Urch, I think the slats were put in there to increase stability of aircraft performance, not decrease it.

 From what I've read, much like the article Wotan suggested, the slat deployment was more of a psychological barrier to inexperienced pilots rather than physical barrier of the plane. A newbie's gotta be scared when he's sweating all over in a tight turn and then suddenly a *bang* and a *shake*

 Another problem seems to be the assymetrical extensions and retractions, which stabilized the plane in near-stall situations, but kept ruining the gun solution.. *bang* *ploop* *bang* *ploop* everytime the air speed went up and down in turns..

 I think I've read somewhere this assymetrical deployment was fixed in latter version 109s..

I understand that the slats were there to enhance stability- but one of the side effects was they made the plane unstable in a firing solution by banging out assymetrically.  This is a well documented 'feature' (as opposed to a bug lol) of the slats on the 109- and that behaviour is not present on any of our 109s.

[Angus]

Grunherz;)
Just read today that the Spit could not be pushed into a snap.
here it is: (hence the teaser)

"Flying the Spitfire was like driving a sports car. It was faster than the old Hurricane , much more delicate. You couldn't roll it very fast, but you could make it go up and down much easier. A perfect lady. It wouldn't do anything wrong. The Hurricane would drop a wing if you stalled it coming in, but a Spitfire would come wafting down. You couldn't snap it into a spin. Beautiful to fly, although very stiff on the ailerons - you had to jam your elbow against the side to get the leverage to move them. And so fast!!! If you shut the throttle in a Hurricane you'd come to a grinding halt; in a Spitfire you just go whistling on.
[1] P/O H.G.Niven 601 & 602 Squadrons, having flown both Hurricane and Spitfire. "

Sort of a paradox to what happened to many a Spit pilot who "Spun in"

Anyway, the 109 was much more "stable" on the vertical axis than the Spitfire, and doubtlessly a lovely balanced aircraft within a certain speed envelope. However with double the wing loading of the Spitfire, it could be pushed beyond the limits.
Actually I heard the thing about the "snap" from Gunther Rall.
He said that if you would try to push the 109 too far, it would eventually snap, while under the same cirkumstances, the Spitfire would not.

[GRUNHERZ]

Every plane has "limits" and the plane can be pushed  beyond them. Even the Spitfire has horribly high winglading compared to lets say an Extra 300. It's all relative.  

[HoHun]

Hi MW,

Great diagrams! I didn't know they came that close to energy manoeuvring in WW2 :-)

Though it doesn't affect the instantaneous turns, the Me 109E example the RAF tested might not have been entirely up to the manufacturer's specifications with regard to power. I think at 12000 ft, it should top out at closer to 345 mph than the 335 mph indicated in the diagram you posted. This indicates that it was probably lacking quite a bit of power, adversely affecting its low-speed sustained turning ability (which is one area of inferiority, according to the RAF tests).

However, in general, can be no doubt that the Spitfire I generally outturned the Me 109E. Galland in "The First and the Last" describes how the Luftwaffe pilots were frustrated by the Spitfire's manoeuvrability until Mölders and Galland devised high-speed tactics to counter it. Quite opposite to what was stated in the article referred to above, it was the reluctance of the Luftwaffe pilots to turn that made the RAF think they didn't trust the strengths of their planes. Far from it - but turning would have given the advantage to the Spitfire which was superior in this area.

Even Galland's comment "I'd like to have a squadron of Spitfires" aims at the different strengths of both planes. Galland believed the Me 109 was the better fighter plane, but he knew that by following Göring's orders and flying close escort for the bombers, they'd get caught without height or speed advantage so they'd have to rely on defensive turning - and that was the Spitfire's strength, not the Messerschmitt's.

Regards,

Henning (HoHun)

[gripen]

HoHun,
Actually flight envelope concept was known long before war. So far I have found/seen (flight tested) flight envelopes for: Spitfire I, Bf 109E, F2A,  P-51, P-47, P-38 and F4U.

IMHO speed/g-load diagram is easier  to use than turn rate /speed  diagram.

gripen

[mw]

Ho-hun:  Top level speed for the 109E was found to be 355 mph at 16,400 ft.  In fact the RAE report states that the "top level speed agreed well with the published figure" (in Germany). I have quite a number of trials reports related to the 109E.  I've seen no mention of the engine being underpowered or having problems.  The report did mention that the radiators were opened up to 13,000 ft during the climb tests for cooling , which explained the discrepancy with the German figures in times to height.  (Interesting side note; Supermarine ran their climb tests with radiator closed too, whereas the British testing establisments opened them for their climb figures).  Hmm, actually 335 mph at 12,000 ft. seems about right to me.  Perhaps more relevant would be the 1200 B.H.P at 12,000 ft. posted.  Does this seem correct to you?  For comparison purposes the British were quick to point out that the DB601N used in the 109F they tested did have problems and the figures should be "treated with reserve".

I'm surprised no one picked up that the Spit was only running at +6.5 lbs/sq. ft.  Running at +12 lbs. with 100 octane fuel would increase the power of the Merlin III by about 25% at 12,000 feet, according to the engine charts I have.   Now that would make a difference

funked

Zig, yea, I have more

[HoHun]

Hi Gripen,

>Actually flight envelope concept was known long before war.

Yes, but I was referring to the lower diagram in figure 18 which actually maps specific excess power.

(The other application for specific excess power diagrams I know from WW2 are the climb diagrams for the Me 262, which established the standard method for graphical climb optimizations for jet aircraft.)

>IMHO speed/g-load diagram is easier  to use than turn rate /speed  diagram.

I agree! I guess the turn rate diagrams are predominant because turn rate was considered a key parameter until the 1960s, when excess power took over.

Regards,

Henning (HoHun)

[gripen]

HoHun,
Ah, I missunderstood  your point. Anyway, that "angle of straight  climb" in the  flight envelope is very handy and you can see relation between it and excess power.

gripen

[illo]

Even Galland's comment "I'd like to have a squadron of Spitfires" aims at the different strengths of both planes. Galland believed the Me 109 was the better fighter plane, but he knew that by following Göring's orders and flying close escort for the bombers, they'd get caught without height or speed advantage so they'd have to rely on defensive turning - and that was the Spitfire's strength, not the Messerschmitt's.

I was always under impression he wanted those spitfires for training and mockfight purposes. And eventually got few which were rotated around fighter bases to educate pilots of spitfires handling.

[Wotan]

heres AG himself explaining what he meant

AG wav

[Seeker]

From Wotan's link:

 "Add to this that even similar aircraft vary in performance from example to example, and it is no wonder that performance comparisons are so difficult and opinions are so varied!"

I wish more people would remember this when squeaking about plane performance.

[Virage]

What is the 'Corrected Airspeed' at the bottom of MW's charts?  

Vi (indicated airspeed?) - something.   ??

[Andy Bush]

>>IMHO speed/g-load diagram is easier to use than turn rate /speed diagram<<

There are several ways of showing energy performance. Your preference is one that is common in EM texts.

Just as common is the chart that substitutes turn rate for G. This chart is particularly useful when constructed as a "differences" chart...meaning, a chart that combines the performance values for two aircraft on one chart. In doing so, meaning comparisons can be easily seen.

The same can be done when using G...but the intuitive lessons learned are not as obvious.

[gripen]

Andy,
Well, there are two reasons why I prefer  V/g presentation in the case of the WWII fighters.

1. It is a direct flight envelope and  WWII  fighters could be maneuvered only inside flight envelope, outside envelope (in stalled  or buffeting areas) they were more or less out of controll. Current  fighters can do maneuvers outside conventional flight envelope, so in that case turn rate aproach might be better way to present turn performance.

2. With V/g diagram connection to the size of the turn circle is also a  bit straighter. In the continous turning attacking fighter must turn inside target (ie should do smaller turning circle) to get to the firing position despite what ever continous turn rate it could reach at higher speed.

Anyway, both ways do the  job. All  war time presentations  I have seen are V/g diagrams, current presentations are mostly turnrate based.

gripen

[Andy Bush]

If this is a little confusing, here are two EM charts...one for a F-4, the other for a MiG-21.

The MiG chart uses airspeed and turn rate as the axes, while the F-4 chart uses airspeed and G.

The curving lines inside the envelope that have plus or minus signs show how much excess energy the planes have at any point. Plus means the airplane at that G and airspeed can still accelerate or climb...the minus sign means that the plane is losing speed at that G and airspeed. The zero line (known as the "zero Ps" line) is the place where the plane can sustain its G at the given airspeed.

Which type of chart to use is mostly a matter of individual preference.