The 'Great Debate' - Spitfire vs BF109

[bongodriver]

Originally Posted by 5./JG27.Farber

Isnt it, "as cunning as fox thats just graduated in cunning at oxford univeristy and recently been apointed professor of cunning at said university"?

But you know, thats eyewitness statements...

No thats pure plagiarism....

[5./JG27.Farber]

Originally Posted by bongodriver

No thats pure plagiarism....

Is it? How come were not discussing the OP?

[TomcatViP]

Regarding the stall and to add material to what I was describing when Bf109 and Supermarine Spitfire are in a turn fight, here come an extract of the doc available here : http://ntrs.nasa.gov/archive/nasa/ca...1993092582.pdf

As you can see, Stall manoeuvring require a lot of power and degrade the ability to turn tight (Cl reduced).

Note :
- "Average" as it was hard to precisely control the amount of G you wished (see Crumpp thread)
- The violent stall buffet was characterized by an abrupt unloading from 5G to 1G

This is inherent to elliptial wings that, ideally (means theoretically), are stalling at once (no tip stalling like with a tapered planform or at the wing roots like a rectangular one).

As I hve said it many times, a turning fight with a SPit Vs 109 hve many similarities with that of a Mirage200 vs an F16 all proportion guarded. You might be interested to document yourself on the latter example to get an idea of what I am trying to describe.

EDIT: click here to see what I was writing http://forum.1cpublishing.eu/showpos...&postcount=107

[Fenrir]

Originally Posted by TomcatViP

This is inherent to elliptial wings that, ideally (means theoretically), are stalling at once (no tip stalling like with a tapered planform or at the wing roots like a rectangular one).

This is where extra research is your friend Tomcat. Lookup 'washout' in terms of Spitfire wings. You could be surprised.

The Spitfire buffet that so many Spitfire pilots talked about was dure to this washout. The wing stalled at the root first, providing the rumbling feedback that so many Spitfire pilots have quoted as riding - the outer wing and the ailerons were still flying giving until the stalled airflow moved outwards if the turn was tightned or speed decreased or both.

So, wrong on that one I'm afraid.

[TomcatViP]

did you read the doc ?
1. graph is stated with "no washout"
2. the test describe a real flight test

I am not professoring Fenhir. I give explanation. Stall description -> theorized phenomena.

The goal is to make more players aware and immune to evangelist of one side or another.

But I cloud hve completed with more: look af the Re along the wing. You'll understand why ell wing are an illusion.

Or with the wing spar.

Geo Wash out is to prevent stall eh yeah and prevent aileron loss of ctrl. But in the case of that wing planform it's a draggy configuration. And drag and lift I was talking about little Jedy.

but buffet is due to the aero washout (the turbulence hitting the elevator) not the geometrical washout on the wing.

If you had take the time to read the doc linked in my post, you'd see this point. I gave plenty of info for the reader to make his own mind and to draw the same conclusion. You'd see, it's an honest behaviour far far away from a post that pick parts of the info and mud it with sarcasms.

Hve fun

[Glider]

Taking a look at it a different way the Difference between the Spit and the 109 tended to flow as different types came into service.

From a personal point of view this is how I see it.

BOB
I go for the Me109 as I prefer its weapons and also because by simply pushing the stick into a neg G the 109 has a very effective escape option that is very quick and very easy to do even by the rawest of recruits.

Me109 F2 vs Spit IIb
I go with the SPit as the weapons on the F2 were too light, something quickly resolved

Me109 F4 vs Spit V
For fighter vs fighter the Me109 had the edge, but it has to be said that the SPit was more flexible as a GA aircraft.

Spit IX ve Me109 G
The SPit IX had the advantage. It was a better HA fighter, the increased speeds of both aircraft also played into the hands of the SPit. Both were affected but the Spit was less impacted and finally the GA was becoming more important for both sides and the SPit was a better GA aircraft, Not a great one but better than the Me109.
Early 109G's had a serious problem with wing failures again resolved but its a factor.

Spit XIV vx 109 G
just magnified the difference

Summary
For the first half of the war the difference was close but the SPit was more flexible and this showed in the second half of the war. Finally in the often forgotten but vital PR role the difference was huge in the Spits favour.

[Glider]

Topcat
You keep posting this as if its undeniably right but I believeit t have some serious items missed so have posted my comments. I do not pretend be an expert in areodynamics but was taught the basics a long time ago.

Feel free to correct my memory

Well once again you are picking extract here and there to build an argument. I only wonder if you did build yourself that way (I speak rudely tht way because I don't like your tone and especially the way you behave as ever tht look like to say: hummph, if you can't answer to this right now then you fail).

I thought it was my aruements that upset you not tone

At first, did you notice that we are talking rather differently of slow speed turns ? All the argumentation is based on physics and pilot accounts and turn around the stall characteristic of the Spit wing.

I had noticed and I also noticed that in the flight tests the Spitfire could stay with the Me109 when the Me 109 stalled. This I believe to be clear evidence that the Spit was better at slow speed.

if you take the both the 109 and the Spit at constant turning speed the SPit will always have an inferior radius as the Hurri will have with the Spit.

You do have examples of this don’t you.? If so I invite you to post them remembering that the RAF and Luftwaffe test establishments both agreed that the Spit would easily turn inside the Me109, as did the pilots both German and RAF who flew the Spitfire
The prob with the SPitfire is her configuration : the thin wing, the wide chord, the low span ratio and the elliptical shape. In the order of appearance it will increase the AoA, aggravate the drag generated by the turbulence around the airfoil and aggravate the stall characteristic and makes the airflow around the wing tips unpredictable (hence the exaggerated washout).

Wrong I am afraid. In the order of appearance
The thin wing - reduces drag, I am not aware of it increasing the AoA,

The chord - the elliptical wing may not differ as much as you think from the Me109. As I remember it it’s the Mean Aerodynamic chord that matters. On a wing such as the Spit the Mean Chord is some way out from the fuselage as there is a significant difference from the root of the wing and the tip. The Me109 wing doesn’t at first glance change much and will be closer to the root of the wing. There will be a difference but not as much as at first glance.

The elliptical wing - is particularly good for low drag. and while the washout will have an impact on the lift, it does give the ideal warning before the aircraft stalls. It should be noted that the washout on the Spitfire is not exaggerated. Indeed the washout on an elliptical wing is far less than the washout needed for a tapered wing to have the same impact
The more you turn, the more E you loose. This E deficit is only compensated by your engine. The more excess of power you have the more time you will stay in that configuration. The Spitfire had less P/W ratio than the 109 (except perhaps in your 12lb+ dreams and what will come next in your request) and thicker wings.

Partly right but you have forgotten the impact of drag which is at least as important. I do not know the figures for these two aircraft. The 12lb boost was in common use in the BOB and the PW ratio was very close even without the extra boost.
It should be noted that in the flight tests by both the German and RAF test establishments the spit always turned better whilst maintaining height. Which would indicate that the impact of Drag vs PW was if anything in favour of the Spitfire
You think you are a pilot so you know what come next..
Of Gliders where PW ratios are not a real issue.

The Spit will have to turn slightly nose down to compensate for the E loss generated from her draggier turn characteristic and inferior P/W and stay away from the low speed/high AoA/Split angle and bank dangerous situation. Invariably the plane with better stall behavior and superior P/W will stay longer in a turn where the speed decrease hence will loose less alt.

So either the Spit pilot will have to unleash the G before his opponent or will he start to spiral down.

In a turn fight, alt his G (you add the Gravity force to what your plane can do).
I believe this to based on a false assumption as outlined above. You also ignore the lift available, there is lift in a turn and that should be considered
Talking about the 109 and Spits models alternatively taking the leads in the perf race is all about this: the aerodynamics and the P/W ratio. Once one get the upper hands, it felt more dynamics in a dogfight and keep that ounce of extra E to get the advantage in a high G engagement.

the fact is that the Emil model had the advantage during BoB.

As mentioned before if you can find more than one German orf RAF pilot who believes that then again I invite you to post it.

Just like The FW190 enjoyed before the IX was launched. (yeah I know you also believe that the 190 was the tank Oleg sold to us with the first opus of IL2)
As mentioned before can you tell me where I ever said that the Fw 190 was less than exceptional? You do have a habit of making statements like this which are wrong I invite you again to support your statement or withdraw it

[Crumpp]

In the turn, the violent buffet is a double edged sword. There is no such thing as a free lunch especially in physics. In the NACA measured results, encountering the buffet represents a change in available angle of bank. The airplane goes from 78.5 degrees of bank to 60 degrees of bank in one second.

****5G @ 147.73KIAS:

ROT = 1091*tan(78.5) divided by 147.73 KIAS = 36.2 degrees a second

****2G @ 141.647 KIAS:

ROT = 1091*tan(60) divided by 141.647 = 13.34 degrees a second

As a quick ballpark using IAS to get an idea of the scope of the effect on turn performance, we see the rate of turn drop from 36.2 degrees a second to 13.34 degrees a second. That means our time to complete a 360 degree turn changes from 10 seconds to 27 seconds!!!

As the Operating Notes relate, you do not want to turn any airplane in the buffet. Energy cannot be created or destroyed, all the energy that was being used to achieve an instantaneous performance rate of turn of 36.2 degrees a second from our ballpark went to warn the pilot of an impending stall, taking the aircraft right down well inside its sustainable performance envelope of 13.34 degrees a second.

[Igo kyu]

@ glider: Eugh. Please learn to quote.

Eg:

First quote.

[Crumpp]

buffet is due to the aero washout (the turbulence hitting the elevator)

I agree the elevator is going to be hard to control from the buffet moments and disturbed flow off the wings.

The buffet itself is caused by flow reversal in the stall portion of the wing. As the flow reverses, it creates suction which creates drag, as our drag goes up, so does our lift. On the thrust axis, weight and engine thrust have to oppose that drag and the airplane will move to a new equilibrium point.

The large ample stall warning buffet comes from high energy flow reversal.