549kmh Bf109f2?

[Boaty-McBoatface]

There is something that does not seem right about the sea level BF109 F2 maximum speeds. All figures listed below are for maximum negative stabilizer position at ISA on an autumn map (760mmHG, 15 degrees C). Figures are being compared with the official dev stats found here:

https://forum.il2sturmovik.com/topic/25993-aircraft-flight-and-technical-specifications-and-operational/?p=406720&do=findComment&comment=406720

 

Run the F2 at maximum power it will achieve an incredible 549kmh before it blows. How this is possible with the old DB601N I have no idea, given the DB601E on the F4 at a whopping 1350HP will only get to 551kmh, yet apart from difference in the VDM propeller these 2 planes are externally identical. Therefore you have to wonder how the F2 airframe is so much less draggy to achieve such speed? That's surely too fast for 1175hp of thrust. It also does not come close to the devs data of 528kmh@1175hp, 1.35ata, instead going a much faster 538.

 

 

tl;dr - F2 seems to have gone mad. DB601N engine pushing 549kmh at max chat? F4 with 601E motor doing only 2kph more.

 

Sure I'm missing something here so input appreciated folks.

Edited May 22, 2017 by B0SS

[Bullets]

This is purely anecdotal from my end but I would agree I think the F2 might be on steroids a bit, there have been a few times recently where I have been in a Mig 3 on full pelt and the F2's have no problem catching me down, It was almost easy for them. At sea level at Emergency throttle the F2 is only supposed to be 3kph faster than the Mig (Source : https://forum.il2sturmovik.com/topic/25993-aircraft-flight-and-technical-specifications-and-operational/ ) However on both the occasions for me an F2 closed in from equal height at an extremely fast rate, I didn't think anything of it until now and just checking the tech specs of the aircraft on the forum does make me think something might be up with the F2's power/speed   

 

Let me quickly state I am not biased towards any side and fly red and blue an equal amount 

 

Thanks

[Finkeren]

I will have to test, but 549 kph seems too fast for the F2 on the deck.

[L3Pl4K]

Is it possible to use tacview, for speed checks?

[Boaty-McBoatface]

I will have to test, but 549 kph seems too fast for the F2 on the deck.

 

What did you get Finkeren? Autumn, ISA, 300m start altitude, maximum negative stabilizer, full throttle F2 until engine blows. 549kmh, I couldn't believe it myself. I did it multiple times. It is insanely fast for a DB601N with far less power than a F4 or G4. 

Edited May 20, 2017 by B0SS

[6./ZG26_5tuka]

Sure I'm missing something here so input appreciated folks.

The Bf 109 F2 has the DB601N with higher clearance (1.42 ata @ 2800 RPM instead of 1.42 ata @ 2600 RPM) based on a report on Kurfürsts Bf 109 Ressource website. To compare figures of the Bf 109 F4 with the early F2 model you have to switch prop pitch to manual and adjust it for 2600 RPM. 

To further illustrate the point, a G4 with nearly enormous 1500HP will only reach 540kmh , yet aside from the bulbs on the wings there is no other significant difference in drag from an F airframe.

There are significant differences between the F and G airframes. First of all the G series was heavier and had a larger fin. The G-4 had a different undercarriage (larger main tires + fixed tailwheel) which also contributed a good portion of drag.

Edited May 20, 2017 by 6./ZG26_5tuka

[Boaty-McBoatface]

The Bf 109 F2 has the DB601N with higher clearance (1.42 ata @ 2800 RPM instead of 1.42 ata @ 2600 RPM) based on a report on Kurfürsts Bf 109 Ressource website. To compare figures of the Bf 109 F4 with the early F2 model you have to switch prop pitch to manual and adjust it for 2700 RPM. 

There are significant differences between the F and G airframes. First of all the G series was heavier and had a larger fin. The G-4 had a different undercarriage (larger main tires + fixed tailwheel) which also contributed a good portion of drag.

 

Thank you for pointing that out! Fixed tailwheel on the G4- that explains the extra drag for that airframe. I always thought it was the G6 with the fixed tailwheel.

 

Even so, how does the F2 with old DB601N achieve such a high speed?

Edited May 20, 2017 by B0SS

[6./ZG26_5tuka]

Even so, how does the F2 with old DB601N achieve such a high speed?

Again, the DB601N in the F2 has the higher clearance for emergency power of 2800 RPM vs the usual 2600 RPM. If you want to compare performences you should try to use real sources and not cross comparing aircraft ingame (each of which has a small margin of error that adds up in comparison).

 

The performence chart shows performence values for climb power (1.3 ata @ 2400 RPM) and emergency power (1.42 ata @ 2600 RPM). It also mentions that increasing RPM to 2800 does increase airspeed by 10 to 15 km/h at full pressure altitude.

[Boaty-McBoatface]

I tested the F2 at 2600rpm and it gets 545kph.

 

That aside, I still don't understand why F2 is so fast with 528kph@1175hp thrust vs F4 522kmh@1200hp.

Edited May 20, 2017 by B0SS

[6./ZG26_5tuka]

Did a quick measuring flight with the F2 on Stalingrad autum, 1200, 200m MSL, full fuel, manual RPM.

@ 1.3 ata / 2400 RPM: 507 km/h

 

@ 1.42 ata / 2600 RPM: 535 km/h

 

Both figures appear too high compared to the spreadsheet with the TO power performence diverting significantly.

 

Edit: More accurate test here: https://forum.il2sturmovik.com/topic/29380-549kmh-bf109f2/?do=findComment&comment=474085

Edited May 24, 2017 by 6./ZG26_5tuka

[303_Kwiatek]

So another overspeed plane at deck? We got Mig3 overspeed about 25 kph and now F2? So reliative performance in speed is kept but both planes should be more historicaly correct

[Boaty-McBoatface]

5tuka - it should be 1.35ata not 1.3. appears there's a significant difference.

 

Also I suspect you are not using maximum negative stabilizer settings with those slower speeds? Honestly you can get 549 with this plane at 1.42 boost

Edited May 20, 2017 by B0SS

[Boaty-McBoatface]

So another overspeed plane at deck? We got Mig3 overspeed about 25 kph and now F2? So reliative performance in speed is kept but both planes should be more historicaly correct

The question is why don't they correspond with the official figures from the Devs? They gave us these figures and they said this is what the aircraft can do, but the data is not true. It doesn't correlate with in-game performance.

 

F2 is wildly overpowered.

Edited May 20, 2017 by B0SS

[Original_Uwe]

Don't forget the F-2, according to the game specs, is around 200lbs lighter.

But with VVS being wildly too fast at high altitude I'd call this a wash.

Edited May 21, 2017 by 1./JG54_Uwe

[Boaty-McBoatface]

Weight has little to do with straight line level speed. Weight plays a part in climb and acceleration. 200lbs is irrelevant.

 

And don't go bringing bloody bias and fanboy'ism into this please. This is historical accuracy, nothing more. If you want a bit of Luftwankery - the E7 is too slow. There you go.

Edited May 21, 2017 by B0SS

[=TBAS=Sshadow14]

Thats All Good BUT WHY are you using such an ODD Air Pressures ((860mmHG, 15 degreesC Correlated to flying a plane Deep inside the grand canyon on a very very cold and dense day.) 

Why not use standard air pressure at sea level (5,000ft MSL) for the testing like all modern planes are more or less since 1953.
Standard pressures (so planes should be Tested @ around 632mmHG)




 

[Boaty-McBoatface]

ISA is at 760mmHG, sorry. That's what I used.

Edited May 21, 2017 by B0SS

[6./ZG26_5tuka]

5tuka - it should be 1.35ata not 1.3. appears there's a significant difference.

The document in question is quoting 1.3 ata.

 

Also I suspect you are not using maximum negative stabilizer settings with those slower speeds? Honestly you can get 549 with this plane at 1.42 boost

I'm sure I had although I'm planning on repeating this in a proper mission with adjusted atmospheric settings.

 

Weight has little to do with straight line level speed. Weight plays a part in climb and acceleration. 200lbs is irrelevant.

Weight does have influrence in the upper range. 200lb roughtly equals 65 litres of fuel if you want to test how much of a difference it makes.

 

If you test performence ingame you should always stick to the real conditions as precisely as possible to get the most accurate data from your test.

[Holtzauge]

A tip when comparing speed for the same plane is to use the inverse cube law: All other things being equal, a change in hp results in the following speed change:

 

Vnew=Vold* (Hpnew/Hpold)**(1/3)

 

As an example, in my C++ model I get 526 Km/h @ SL for 1200 hp for the F4 so reducing that to 1175 hp:

 

Vnew=526*(1175/1200)**(1/3)=522 Km/h

 

So yes, based on the test results posted in the OP the F2 does seem to fast in-game now.

Edited May 21, 2017 by Holtzauge

[Original_Uwe]

If the results are accurate

[Holtzauge]

Sure, but assuming the in-game speed numbers mentioned above hold, then as BOSS points out it does not make sense if the F2 is that fast on that amount of horsepower.....

[ACG_KaiLae]

Is it possible to use tacview, for speed checks?

 

I wanted to point this out. Tacview displays the actual TAS of the aircraft, which should make it excellent for checks such as these. It actually displays everything else as well.  

[Venturi]

Like a 96mph stall^

[Boaty-McBoatface]

I wanted to point this out. Tacview displays the actual TAS of the aircraft, which should make it excellent for checks such as these. It actually displays everything else as well.

How can one access tac view?

[=TBAS=Sshadow14]

WHO Cares about TAS
Defo not the plane or any combat situation really.

[Irgendjemand]

WHO Cares about TAS

Defo not the plane or any combat situation really.

 

You serious? TAS is the only value that matters:P

[Finkeren]

You serious? TAS is the only value that matters:P

 

That's a stretch.

[303_Kwiatek]

If results are correct both F2 and Mig3 are too fast at deck for similar error. Still Mig3 coukd fly full boost at least 5 minutes or more where F2 only max 2 minutes. If correction is needed both planes should be affected not only F2

[Finkeren]

If results are correct both F2 and Mig3 are too fast at deck for similar error. Still Mig3 coukd fly full boost at least 5 minutes or more where F2 only max 2 minutes. If correction is needed both planes should be affected not only F2

 

I'm curious what you think the top speed on the deck should be for the MiG-3? I've seen sources ranging from 470 km/h right up to 500 km/h. I just tested and in game the the MiG-3 does 490 km/h on the deck running in boosted mode with fully open radiators (as they should be) This seems to fall within the range of source material.

BTW: I just tested the Bf 109F2.

 

Could only get to 535 km/h on full throttle (automation on), the speed stopped increasing before I reached the engine limit, so it's not because I blew the engine too early.

 

It does 502 km/h in combat mode, so slightly faster than the MiG in boosted mode. A MiG pilot could probably keep up, if he runs his engine a bit hot.

[6./ZG26_5tuka]

Redid the test in a editor made mission with settings for standard atmospheric conditions at 500m MSL (760mmHG, 15°C, no wind / turbulence) with the help of Tacview as a proof of concept.

 

Test conditions: Full fuel, full ammo, no external oridnance, no mods, full stabilizer downtrim (-100%), autolevel, automatic radiator setting, no manual controll inputs, restart mission per iteration (to ensure equal fuel conditions)

 

Results:

 

Power setting: 1.3ata / 2400 RPM

Equivalent:      87% Throttle / 56% Prop pitch (manual pitch enabled)

Max Temporary Airspeed: 519 km/h

Max Continous Airspeed: 517 km/h

 

 

 

 

 

Power Setting: 1.42 ata / 2600 RPM

Equivalent:       100% Throttle / 51% Prop pitch (manual prop pitch enabled)

Max Temporary Airspeed: 548 km/h

Max Continous Airspeed: 547 km/h

 

 

 

 

 

If there's interest I can also upload the mission (there's nothing special to it apart from atmospheric test conditions).

Edited May 22, 2017 by 6./ZG26_5tuka

[ACG_KaiLae]

How can one access tac view?

Buy it. The pro version costs 70$.

[303_Kwiatek]

I'm curious what you think the top speed on the deck should be for the MiG-3? I've seen sources ranging from 470 km/h right up to 500 km/h. I just tested and in game the the MiG-3 does 490 km/h on the deck running in boosted mode with fully open radiators (as they should be) This seems to fall within the range of source material.

 

BTW: I just tested the Bf 109F2.

 

Could only get to 535 km/h on full throttle (automation on), the speed stopped increasing before I reached the engine limit, so it's not because I blew the engine too early.

 

It does 502 km/h in combat mode, so slightly faster than the MiG in boosted mode. A MiG pilot could probably keep up, if he runs his engine a bit hot.

Mig3 versiin like we have in game nominal power maximum speed 475 kph at deck and 500 kph with boost. In game ISA condition no problem it reached in prolonged flight 525 kph with bost at deck.

[Finkeren]

Mig3 versiin like we have in game nominal power maximum speed 475 kph at deck and 500 kph with boost. In game ISA condition no problem it reached in prolonged flight 525 kph with bost at deck.

525 km/h sounds like a lot. Don't think I've ever done that. I could probably get to 515 km/h by closing radiators almost completely and running the engine very hot, but that's not how the tests were done historically. There you'd open the radiators fully for tests under full power.

 

If you open the radiators fully you'll find, that the MiG can'teven reach 500km/h in boosted mode on the deck. Perfectly in line with test data.

[6./ZG26_5tuka]

Buy it. The pro version costs 70$.

The basic version is for free and has all the functions needed for FM testing for a limited ammount of time.

Edited May 22, 2017 by 6./ZG26_5tuka

[6./ZG26_Klaus_Mann]

 

 

There are significant differences between the F and G airframes. First of all the G series was heavier and had a larger fin. The G-4 had a different undercarriage (larger main tires + fixed tailwheel) which also contributed a good portion of drag.

 

Nope, the G-1 through G-4 were basically F-4 Cells with the new Window, Heavy Window framing, the DB605 and Cowling. Aerodynamically they didn't change anything until the G-6/AS  and G-14 except for Wheels and MG Bulges. 

The Wings only gained 1 Rib behind the Ailerons and slightly thicker Skins in Order to Improve Rate of Roll at high Speeds. 

 

Both the DB601N and DB601A are running 1.42ata/2800 but the F-2 still has the same Propeller Type as the Emils. The Changeover to the smaller 3m Diameter Props came with the F-4. 

The F-2 also has somewhat smaller Radiator Inlets than the F-4 and Gustavs as well as a smaller Oil Cooler. 

 

The Ingame G-2 at 1.42 ata would get up to about 550-555 on the Deck. 

 

Just stating Facts, no Conclusions. 

[Holtzauge]

Just a comment on the F2 speed results 5tuka posted: If you want to compare that to Han's in-game figures which are given for SL IIRC, the SL TAS speeds would probably be in order of 10-12 Km/h TAS lower than at 500 m.

[6./ZG26_5tuka]

Nope, the G-1 through G-4 were basically F-4 Cells with the new Window, Heavy Window framing, the DB605 and Cowling. Aerodynamically they didn't change anything until the G-6/AS  and G-14 except for Wheels and MG Bulges. 

The Wings only gained 1 Rib behind the Ailerons and slightly thicker Skins in Order to Improve Rate of Roll at high Speeds. 

 

Both the DB601N and DB601A are running 1.42ata/2800 but the F-2 still has the same Propeller Type as the Emils. The Changeover to the smaller 3m Diameter Props came with the F-4. 

The F-2 also has somewhat smaller Radiator Inlets than the F-4 and Gustavs as well as a smaller Oil Cooler. 

 

The Ingame G-2 at 1.42 ata would get up to about 550-555 on the Deck. 

 

Just stating Facts, no Conclusions. 

Rechecked my source and figured I might have jumped on conclusions, although it does suggest that changes were introduced with the G series (doing further ressearch on the subject I coudln't find additional supportive material).

 

Anyway there's the report in question:

 

 

 

Just a comment on the F2 speed results 5tuka posted: If you want to compare that to Han's in-game figures which are given for SL IIRC, the SL TAS speeds would probably be in order of 10-12 Km/h TAS lower than at 500 m.

With the SL pressure level raised to 500m there shouldn't be a noticeable difference in IAS and TAS (as proven by Tacview).

Edited May 22, 2017 by 6./ZG26_5tuka

[6./ZG26_Klaus_Mann]

 

 

Rechecked my source and figured I might have jumped on conclusions, although it does suggest that changes were introduced with the G series (doing further ressearch on the subject I coudln't find additional supportive material).

That's the enlarged tail of the Gustavs, G-6AS, G-14 and G-10 as well as K-14. In that Report they still though they would make it from Metal, but later switched to Wood and further enlarged it.  But as far as F-4 to G-1 through G-6 is concerned the Tail remained almost basically the same. 

[Holtzauge]

With the SL pressure level raised to 500m there shouldn't be a noticeable difference in IAS and TAS (as proven by Tacview).

 

OK, sorry I missed that part and I see what you mean. Smart setup!   

[303_Kwiatek]

525 km/h sounds like a lot. Don't think I've ever done that. I could probably get to 515 km/h by closing radiators almost completely and running the engine very hot, but that's not how the tests were done historically. There you'd open the radiators fully for tests under full power.

 

If you open the radiators fully you'll find, that the MiG can'teven reach 500km/h in boosted mode on the deck. Perfectly in line with test data.

 

From game data:

 

MiG-3 series 24

 

Maximum true air speed at sea level, engine mode - Boosted: 525 km/h

Maximum true air speed at sea level, engine mode - Nominal: 493 km/h

Maximum true air speed at 7600 m, engine mode - Nominal: 626 km/h

 

I reached similar results in game ( autum map +15 deg) with no problem prolonged flight without overheating. If you cant probably you are doing something wrong.

Edited May 22, 2017 by 303_Kwiatek