Which fighter specs reveal acceleration capabilities?

[Youtch]

What does determine acceleration capabilities of a fighter, while flying horizontal at sea level?

 

Are there any specs available that provide information on how good a plane is at accelerating, and compare with the others?

 

Is it mostly power/weight ratio or there are other key elements?

 

Do plane with similar power/weight ratio last similar time to accelerate from 200kph to 300kph in a horizontal plane at sea level? Regardless of their actual size and weight? Tempest for instance seems to have a power weight ratio similar to bf109 but i am under the impression that it accelerates slower.

 

Many thanks in advance,

Y.

[PB0_Roll]

Aerodynamics count too. From 0 to 100 it's not exactly relevant, but from 200 to 300 it is.

 

Plus max power is given for a certain altitude and RPM, that can be drastically different from plane to plane. 

[Gingerwelsh]

Real.

 

From this you could deduce, P/W ratio is the key.

 

 

..

Edited January 4, 2023 by Gingerwelsh
Added text.

[Youtch]

According to this chart the power/weight ratio for ww2 aircrafts

 

 

The acceleration of Tempest 2 is not corresponding to its power/weight, hence my initial question.

 

 

Edited January 4, 2023 by Youtch

[RyanR]

I usually just look at climb rate, as it loosely correlates with P/W ratio.

 

There are still so many variables that get lost when you distill "performance" down to a single number. Like, "acceleration at what power setting", and "from what speed to what speed".

 

Power settings are so important in GB. Doesn't an La-5FN have no limit to full throttle? A 109 with MW-50 is burning a finite amount of the stuff to keep the engine from exploding.

 

-Ryan

[Guest deleted@83466]

1 hour ago, Youtch said:

According to this chart the power/weight ratio for ww2 aircrafts

 

 

The acceleration of Tempest 2 is not corresponding to its power/weight, hence my initial question.

 

 

Tempest probably more draggy, or a factor of the particular propellor…you can’t simply judge acceleration by P/W ratio alone, you have to look at the forces on the whole airplane.  What’s the force forward through the prop, what’s the force of drag in the anti direction, etc. 

[Dragon1-1]

P/W ratio isn't the whole story, unlike with jets, where T/W ratio lets you compare even very disparate designs. With props, RPM matters a lot, and prop design (disc diameter, blade count, blade profile) can have considerable impact on how well it can accelerate the plane, and at what speed it works best.

[JG27*PapaFly]

Loaded acceleration during level flight at 1g is not telling you much about acceleration ability during combat. Depending on stall speeds and of the starting speed,  induced drag can have a major influence.

 

During combat,  unloaded acceleration is more important. It takes induced drag out of the equation and is always superior to level flight acceleration.  It is performed while pushing the stick forward to eliminate most of the lift-induced drag (0 - 0.5 g).

[Youtch]

So, how do we know which are the good planes for quick acceleration, and how does it get quantified?

[NightFighter]

If you are looking strictly for in-game aircraft acceleration, you can run tests in the quick missions as long as you repeat them under similar conditions. I just ran a simple acceleration test on the Rhineland Summer 1944 map at 15:00 time with no wind, no clouds, no haze with the Spitfire Mk.IX, Bf109G-6 Late, and P-51B-5:

 

I had each aircraft stabilized at 1,000ft at 150mph (241kmh), then firewalled the throttle and timed how long it took to reach 300mph (482kmh);

 

Spitfire Mk.IX (300L of Fuel, 150 Octane Modification) : 31.875 seconds average 

 

Bf109G-6 Late (300L of Fuel, MW-50, Erla Haube Modification) : 36.425 seconds average

 

P-51B-5 (400L of Fuel, 150 Octane Modification) : 36.81 seconds average

 

*Repeated each aircraft test three times

 

I then ran the aircraft in a similar test at 1,000ft, stabilizing them at 300mph (482kmh), then timing how long it took to reach 330mph (531kmh)

 

Spitfire Mk.IX (300L of Fuel, 150 Octane Modification) : 18.06 seconds average 

 

Bf109G-6 Late (300L of Fuel, MW-50, Erla Haube Modification) : 23.07 seconds average

 

P-51B-5 (400L of Fuel, 150 Octane Modification) : 16.96 seconds average

 

*Repeated each aircraft test three times

 

So the average acceleration of the aircraft from the "low" speed test (150-300mph) was;

 

Spitfire Mk.IX : 2.1 m/s/s

 

Bf109G-6 Late : 1.84 m/s/s

 

P-51B-5 : 1.82 m/s/s

 

*All speeds converted to meters per second (m/s)

 

The average acceleration for the high speed test (300-330mph) was;

 

 Spitfire Mk.IX : 0.72 m/s/s

 

Bf109G-6 Late : 0.56 m/s/s

 

P-51B-5 : 0.77 m/s/s

 

*All speeds converted to meters per second (m/s)

 

The Spitfire has the edge in the low speed flight regime, with it and the Bf109 both outpacing the Mustang. However, the Mustang accelerates faster in the higher speed regime, which makes sense. I did find it odd how the spitfire still has good high speed acceleration because the original high speed test was 300-350mph but the spitfire capped out at 342mph (which is why I changed it to 300-330mph). Take the results with a grain of salt, I did these tests relatively quickly but given more time you can come up with good data. You can repeat this with all the aircraft you like and come up with your own criteria which might better represent multiplayer combat in game.

 

Edited January 4, 2023 by NightFighter

[JG27*PapaFly]

1 hour ago, Youtch said:

So, how do we know which are the good planes for quick acceleration, and how does it get quantified?

Through flight tests, data analysis and visualization. Here are diagrams of level acceleration tests I did some time ago.

 

[Youtch]

11 hours ago, JG27_PapaFly said:

Through flight tests, data analysis and visualization. Here are diagrams of level acceleration tests I did some time ago.

 

I understand the 2nd diagram with true airspeed shall be more representative.

 

I am not sure i understand the diagram though, why time is decreasing for the first 50kph, shouldn t it be increasing all the time? Or it is the time to increase 50kph at different speeds?

 

Is the game somehow realistically implementing acceleration?

 

This must be modelized somehow in the game as well, is there any way to get access to the raw data?

[JG27*PapaFly]

The 1g level acceleration is very easy from a test perspective. Engaging the level stabilizer ensures highly reproducible results. 

 

Testing the unloaded acceleration is trickier, as the maneuver must be flown manually, and the dive component introduces a high degree of variability in the results (variations in dive angle, air density differences throughout the dives to denser air). 

[JG27*PapaFly]

7 minutes ago, Youtch said:

I am not sure i understand the diagram though, why time is decreasing for the first 50kph, shouldn t it be increasing all the time? Or it is the time to increase 50kph at different speeds?

 The second diagram shows how much time each plane needs to increase its current speed by 50 kph, across a range between 200 - 500 kph. For the FW190A5, you clearly see that the plane accelerates faster between 250-300 compared to 200-250 kph. That's the effect of induced drag: at 200 kph the plane is near its clean stall speed and thus flies at near maximal AoA in order to maintain altitude. Induced drag slows acceleration considerably. As speed increases to 250 kph,  AoA and induced drag decrease, and acceleration increases.

[Jaegermeister]

The simple answer is power to weight ratio minus drag.

 

Things like radiators, air intakes and frontal area are significant to acceleration.

 

Propeller design also plays a part like with the addition of the "paddle prop" on the P47D.

 

[Youtch]

Is the game somehow realistically implementing acceleration? I understand he does not need to be 100% realistic, but is it somehow realistic?

 

This must be modelized somehow in the game as well, is there any way to get access to the raw data without having to reverse engineer performance of each aircraft through in-game measurements?

[PB0_Roll]

Acceleration is not a set number, but a result of a non constant combination of numbers, I'm afraid you'll have to go with test results.

[RossMarBow]

On 1/5/2023 at 2:55 AM, Youtch said:

What does determine acceleration capabilities of a fighter, while flying horizontal at sea level?

 

Are there any specs available that provide information on how good a plane is at accelerating, and compare with the others?

 

Is it mostly power/weight ratio or there are other key elements?

 

Do plane with similar power/weight ratio last similar time to accelerate from 200kph to 300kph in a horizontal plane at sea level? Regardless of their actual size and weight? Tempest for instance seems to have a power weight ratio similar to bf109 but i am under the impression that it accelerates slower.

 

Many thanks in advance,

Y.

Its complicated.
I measure acceleration myself.
109s have the best acceleration. 
But I was only comparing them with the russian planes.
Other peoples data above looks good too.

For my tests I just measured 300-400kph acceleration while firewalling throttle auto level flight 1KM height. 
And the data I got was useful for me.
Looks like planes behave differently at higher speeds which is understandable. 
And someone mentioned unloading I have no idea how big of an effect that has.
If you wanted to understand a plane better I would test it how you plan on flying it.
I just used the information so I could better understand the strengths and weaknesses of different planes.
For example, the yak1b is basically equal in acceleration to the G6. 
So I only fly the 9T because it has the worst acceleration yes, but your not gonna beat 109s accelerating anyway. 

Edited January 20, 2023 by RossMarBow