Spit/109 sea level speed comparisons in 1.08 beta patch

[JtD]

Originally Posted by Crumpp

Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

[Robo.]

Originally Posted by JtD

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

Yes that pretty much nails it.

The speed advantage is still speed advantage as JtD said it 100% ly - ''This remains true in turnfights. The 109 has the choice to maintain the higher airspeed at a lower corner velocity, the Spitfire has the choice to maintain a higher corner velocity at a lower airspeed, so the 109 can maintain the initiative.''

[Crumpp]

An obvious statement but the Spit trials you quote above seems to be without the extra boost that 100 octane allows.

It does not change the outcome or outlook. Despite the higher wingloading, the Bf-109 has more excess thrust because it is lighter.

JtD says:

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity.

How is your statement ANY different from mine????

Crumpp says:
Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.

Performance in the context of the conversation is TURN performance.

The Spitfire has to reduce speed significantly below the Bf-109's to reach that best turn velocity.

That is a fact.

According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

That is one way of looking at it.

Another way is the Spitfire must give up 30 kph of speed in order to realize any advantage at all.

It is the same exact scenario. One that leaves the Spitfire with no choice but hope it sticks around in the turn fight.

If the Bf-109 does not, the Spitfire has lost the initiative.

[Crumpp]

Do you know what would happen if you entered a pure turn and burn (TnB) fight against a Spitfire (you in a 109)?

Sure, you would use the Bf-109's sustainable load factor advantage to put the Spitfire turning defensive circles beneath you until you killed him.

[Crumpp]

A second observation, can someone explain how the Me109 is supposed to have a better manoverability at higher speeds than the SPitfire when all the tests point out how difficult the 109 is to manoever at high speeds due to the way the controls stiffen up at high speed compared to the Spitfire?

Don't confuse high load factors found in instantaneous performance with low load factors achievable in sustained performance.

[Robo.]

Originally Posted by Crumpp

Sure, you would use the Bf-109's sustainable load factor advantage to put the Spitfire turning defensive circles beneath you until you killed him.

That's not the TnB mate.

[JtD]

Originally Posted by Crumpp

How is your statement ANY different from mine????

You're saying the 109 is flying at the Spitfires best turn performance speed, I am saying the 109 is flying at its own best turn performance speed. Quite a difference.

[Crumpp]

You're saying the 109 is flying at the Spitfires best turn performance speed, I am saying the 109 is flying at its own best turn performance speed. Quite a difference.

No I am not. I am saying both aircraft are flying best turn performance.

Best turn performance is a specific speed.

In the single point analysis of best turn performance, the airplanes are at different speeds.

When we look at the entire envelope, the Spitfire must be at a slower speed in order to outturn the Bf-109.

[Glider]

First thanks for the replies

My first observation was that the Spit test you used didn't include the extra power from the 100 octane fuel

Originally Posted by Crumpp

It does not change the outcome or outlook. Despite the higher wingloading, the Bf-109 has more excess thrust because it is lighter.

I say it does make a difference as the extra boost came with a significant increase in power which significantly improves the power weight ratio. Also lighter is a factor but a bigger one is drag which is where the 109 loses out.

Re your second reply

Don't confuse high load factors found in instantaneous performance with low load factors achievable in sustained performance

You have a point but nowhere have I seen anything that says that the 109 had a better sustained performance. Also what is sustained? Everyone seems to agree that the SPit turned tighter and faster so what is sustained. Are you trying to say that after X turns the 109 would start catching up because it has a better sustained performance?
My understanding is that a sustained turn rate is one that can be maintained for long periods of time without losing altitude, maximising the turn rate and radius of turn.
On both these counts the Spit will beat the Me109 as proven in the Rae tests which were sustained turns without losing height

Re the Graph,s I still don't understand what you are trying to prove. Lift limit is a new term to me but I assume it has something to do with the max lift the wing will generate given a certain angle of bank, but how load factor impacts this I don't have a clue, as the load doesn't impact lift. Load factor increases with bank which will increase the amount of lift required but lift available in the wing is a constant
Thrust Limit is also a new term to me I assume its a power to weight thing, but again don't understand how load would impact it as thrust is a given depending on height etc but not as far as I am aware load factor. The thrust required is increased as the bank increases but in a given aircraft it is a fixed amount.

[Crumpp]

I say it does make a difference as the extra boost came with a significant increase in power which significantly improves the power weight ratio

What power and speed? I will recalculate and repost.

You have a point

If you understand stability and control engineering, Mtt did a good job on the Bf-109.

Also what is sustained?

It is the performance the engine can perform until it runs out of gas.

My understanding is that a sustained turn rate is one that can be maintained for long periods of time without losing altitude, maximising the turn rate and radius of turn.

Yes

On both these counts the Spit will beat the Me109 as proven in the Rae tests which were sustained turns without losing height

The RAE test's were of turning ability. If you look at the test the RAE flew the airplanes at ~115KEAS in their evaluation.