Spit/109 sea level speed comparisons in 1.08 beta patch

[Glider]

Originally Posted by Kurfürst

Just explain how a plane with less or no excess thrust can pull a sustained turn better than a plane with more excess thrust, thank you.

How much excess thrust does a Spitfire at SL, running at +6 1/4 boost has at about 280 mph 1g at David?
How much more excess thrust does a Spitfire at SL, running at +6 1/4 boost require in 2g turn at about 280 mph David?

Interesting that you keep talking about the 6 1/4 boost and not the 12 boost.

How much excess thrust does a Bf 109E at SL running at 1.35ata bppst has at about 280 mph 1g at David?

less than a 12 boost Spitfire

Which has a better sustained turn at 400 mph David, a Spitfire IX or a Me 262 (P-80 if you like)?

Spit every time.
Show any acual test that says otherwise. Show any 262 pilot who says that he would turn faster than any piston fighter.
No, their advantage was speed and the key was keeping your speed high and making it almost impossible to get a shot at you

I am still trying to work out how the German test authorities got it so wrong. I admit that I cannot find any reason and neither can anyone else, so maybe, just maybe they got it right and the 109 couldn't turn inside the Spitfire, after all thats what their official report says

[Igo kyu]

The Falcon (one) manual told us some things that some seem to have forgotten, if they ever read them at all.

Two aircraft at the same speed pulling the same 'g' force, turn the same radius circle.

The same 'g' force at higher speed means an increased radius of turn, and a lower rate of turn.

At the same speed, a higher 'g' force causes a reduced turn radius and increased rate of turn.

This is why a fighter at .98 mach pulling 8 'g' can outturn a missile at 3.0 mach pulling 30 'g', the fighter's rate of turn is higher.

[ATAG_Snapper]

Which explains quite tidily why a Spitfire 1a never fell to a guided air-to-air missile throughout the entire Battle of Britain......

[Bounder!]

Originally Posted by Igo kyu

The Falcon (one) manual told us some things that some seem to have forgotten, if they ever read them at all.

Two aircraft at the same speed pulling the same 'g' force, turn the same radius circle.

The same 'g' force at higher speed means an increased radius of turn, and a lower rate of turn.

At the same speed, a higher 'g' force causes a reduced turn radius and increased rate of turn.

This is why a fighter at .98 mach pulling 8 'g' can outturn a missile at 3.0 mach pulling 30 'g', the fighter's rate of turn is higher.

I'm a little out of my depth here but... I read somewhere that if speed and 'g' are equal then the turning circle is proportional to the wing loading and that is one of the reasons the spit out turns the 109.

[Igo kyu]

Originally Posted by Bounder!

I'm a little out of my depth here but... I read somewhere that if speed and 'g' are equal then the turning circle is proportional to the wing loading and that is one of the reasons the spit out turns the 109.

If speed and 'g' are equal, then the circle must be the same size.

If a spit and a 109 are at the same speed, then the spit can pull more 'g' because the wing of the spit is bigger, and thus the loading (aircraft weight/wing area) is lower, and pulling more 'g' makes the circle smaller. This may fail as a rule when you get up to speeds where enough 'g' can be pulled to break the airframe, or to black out the pilot, but as I understand it these aircraft would have to be diving to get fast enough to break their airframes. It also doesn't apply below stalling speed.

<edit>

Wing loading isn't all the story, the Hurricane's wing was more heavily loaded than the Spitfire's, and the Hurricane turned better/pulled more 'g' at a given speed. The greater thickness of the Hurricane's wing I think had something to do with that.

[IvanK]

Firstly if you think WWII fighter pilots were going to engage in modern energy theory concepts such as sustained optimum energy speed turn fights you are deluding yourselves. Concepts of Energy bleed Ps rates where not really in the the WWII fighter pilots thought process. Zoom and Boom or general turn fighting was. A spitfire pilots mindset was "I can outturn this 109'. The 109 pilots mindset was "I better be careful and not try to turn with this Spit"

The argument about the (debatable) slightly faster level speed of the 109 over the Spitfire means the 109 must have better sustained turn performance at these speeds is bogus imo. If you accept that for a given flight condition the 109 is faster so therefore has superior energy (Ps) than the Spit so therefore can transform this into turn performance advantage think about this. The superior energy (Ps) is only in 1G flight. As soon as you load the airframe up who has the lesser energy rate loss now ? .... i.e. energy bleed ? Ps at 1G and Ps at say 4G are totally different things ... JTD says it quite clearly and even provides some numbers :

"It's in the physics. If you look (very closely in well hidden places) at the turn calc spreadsheet I attached the other day, you can see that near each planes top speed, the 109 gains ~1.1 °/s turn rate for every m/s of speed given up, while the Spitfire gains about ~1.5 °/s turn rate for every m/s given up. This means in example, for a 9°/s turn rate the 109 loses ~29 km/h, while the Spitfire loses ~22 km/h and has thus narrowed the gap by ~7 km/h. It's a trend that continues until at low speeds the Spitfire becomes superior."

So once the G comes on the 109 is losing airspeed faster than the Spit..... and we know where the fight is going now don't we? 1G Ps and Ps under G are not the same thing.

Thats why JTD says (and is correct imo):

"It really sums up to that the 109's biggest advantage is in flying straight and level, it will remain competitive throughout the high & medium speed range, with the advantage always decreasing. All this, mind you, at sea level against a 6.25lb boosted Spitfire I, which is as good as it gets for the 109. "

Then we have this strange concept of the faster 109 being able to turn better than the Spit at say 400Kmh so therefore he can deny a Spit (at less than 400kmh) closing to a Guns shot ! Its an axiom of Defensive BFM that if you just keep turning a slower aircraft can simply arc inside your turn nose in lead and close to guns. Robbo puts it quite eloquently:

"But it is also possible to cut the corner of the 109 and shoot at it alright at lead curve, then ease up the turn and repeat. All depends on the trajectory, the planes will obviously turn on different circles etc. If you make a deal that the 109 won't climb or scissor, just turn, you will win. Because the Spitfire is much better TnB fighter than Emil. Emil is decent turner, too, very maneuvrable and agile, but as for the sustained turn competition in actual dogfight, Spitfire has got better qualities. "

Kurfurst
"Just explain how a plane with less or no excess thrust can pull a sustained turn better than a plane with more excess thrust, thank you"....

I'll have a go or comment at least We are talking about 2 aeroplanes one with marginally better 1G Ps at lets say 400kmh. As soon as the 109 starts to turn how much of this Ps superiority does he now have ? If his -Ve Ps under G is less than the Spit then fair enough but is it ? JTD's figure show the 109 -ve Ps under G to be worse than the Spit.

The RAE Fan charts (accepted that a couple of people here contest these) show this quite clearly.

[Kurfürst]

Originally Posted by Glider

Originally Posted by Kurfürst
Just explain how a plane with less or no excess thrust can pull a sustained turn better than a plane with more excess thrust, thank you.

How much excess thrust does a Spitfire at SL, running at +6 1/4 boost has at about 280 mph 1g at David?
How much more excess thrust does a Spitfire at SL, running at +6 1/4 boost require in 2g turn at about 280 mph David?

(Glider remains silent on the issue)

Interesting that you keep talking about the 6 1/4 boost and not the 12 boost.

In fact we all do, except for you. The discussion is about trying to explain to you the fact that the 109E has a better sustained turn than the Spitfire using 6 1/4 boost at and above 400 km/h near SL.

less than a 12 boost Spitfire

(Glider remains silent on the issue)

... and how much is that David?

Spit every time.

And why is that, David? How can a Spitfire sustain a turn without any excess thrust to start with? Does it have anti gravity drives perhaps? Can it just defy the rules of physics?

I am sorry David, but I believe that you did not fully grasp some of the basic elements of the this discussion, such as the difference between sustained and unsustained turns, the effects of parasitic and induced drag depending on airspeed and the importance of thurst and excess thrust. So let me put it down for you in the most simply terms:

Unfurtunately, the Spitfire cannot sustain a turn at 400 mph at all. Depending on altitude, it has either ZERO or NEGATIVE "excess" thrust already at 1 g.

We have been over this already anway, see http://forum.1cpublishing.eu/showpos...&postcount=194



In short, the 262 (blue line) starts to run circles around the Spitfire IX (red line) above 460 km/h. At 640 kph, the Spitfire is outright hapless...

I am still trying to work out how the German test authorities got it so wrong.

Nope, they got it exactly right. They say:

In summary, it can be said that all three enemy planes types are inferior to the German planes regarding the flying qualities. Especially the Spitfire has bad rudder and elevator stability on the target approach. In addition the wing-mounted weapons have the known shooting-technique disadvantages.

It seems to me that the Germans regarded the flying qualities of the Spitfire overall inferior to their fighters.

[Glider]

Kurfurst you are full of charts which are calculated by yourself and crumpp, however you never talk about the real tests undertaken by the real pilots and real test establishments.
I know what I know and I acknowledge what I don't.

You talk about the 6 1/4 boost and I talk about the 12 boost. Why, because the RAF fighters in the BOB used 12 boost. You talk about the 6 1/4 boost because that gives the 109 a better chance, not what they faced in combat, a big difference.

The one part of the report that you quote
In summary, it can be said that all three enemy planes types are inferior to the German planes regarding the flying qualities. Especially the Spitfire has bad rudder and elevator stability on the target approach. In addition the wing-mounted weapons have the known shooting-technique disadvantages
You make a big deal on this but forget to mention that the Spit in question didn't have the CSP only the two pitch prop which they rightly make a number of comments about. No one is trying to pretend that the Spit was the greatest gun platform which is part of the equation and they had wing mounted guns, not exactly new.

However you don't quote the bit about turning which is what the conversation is about, interesting. So just to be clear, do you also agree they had it right when they said
Before turning fights with the Bf 109 E type, it must be noted in every case, that
all three foreign planes have significantly smaller turning circles and turning times.
An attack on the opponent as well as disengagement can only be accomplished on the basis of existing superiority in performance.

In which case what are you disagreeing about, or are you only disagreeing with the bits you don't like?

I agree with everything that the report says, will you make the same statement?

As for the 262 I notice another nice chart but nothing re tests or pilot experience so it remains a theory, no more no less.

[JtD]

The chart Kurfürst posted is not a theory, it's a calculation. Physics and maths are just as relevant as tests and pilot experience. There are methods that are standard and accepted. If you use them properly, they can be more accurate than tests and pilot experience and are imho at least as valid.

[Glider]

Originally Posted by JtD

The chart Kurfürst posted is not a theory, it's a calculation. Physics and maths are just as relevant as tests and pilot experience. There are methods that are standard and accepted. If you use them properly, they can be more accurate than tests and pilot experience and are imho at least as valid.

This is the sort of thing that raises my doubts. I am confident that the Grippen had many thosands of calculations undertaken by some of the finest minds in aviation. Using the latest computers, many hours in a simulator and then this happened. I should add that this was being flown by a test pilot.

http://www.youtube.com/watch?v=k6yVU_yYtEc

Show me any report of any 262 pilots who would go into a turning dogfight against a Mustang, Spit, La 7, whatever take your pick. The theoretical world is one thing, hard combat another.
Look at it another way, Why did the Mig 17 do so well against the F4, F105 and so on. Find any US pilot who would go into a turning combat in any of the above against an old slow Mig 17.