Speed graphs for Spitfire and Hurricane

[Sven]

Originally Posted by Kurfürst

For comparison, the actual flight test (note the two lines, the bold one is the speed measured with the engine slightly down on power by about 50-60 PS, the thinner line is the measured performance re-calculated for nominal engine output guaranteed by engine manufacturer)

This has been achieved with 1.33/1.35 ata, which is our firewalled throttle setting in the game, without resorting to the 1-min WEP.

Would you say that with the data from that flight test that ~500 kmh could be achieved on the deck for a longer period of time in the BF109E without risking overheating ( which would happen only with emergency power of the 1-min WEP? ). And is there a graph which shows us the maximum speed when the BF109E is using the 1-min WEP?

It seems the devs think that ~500 kmh on the deck ( 0m ) can only be achieved with use of this 1 min WEP, which is not what your German Data speed graph lets us believe, Kurfurst's 1.33/1.35 ATA versus 1C's WEP 1.4 ATA to achieve 500. Quite a difference in terms of aircraft modelling.

One last thing, is this also a 'firewalled throttle without WEP' graph?



About the new Spitfire speed data, I don't want to see the SpitII replacing the Spit I on the servers, this should not be the solution. Dev team should look at 100 Octane SpitI speed figures which confirms that both the BF109E and SpitfireIa, if correctly modeled, are very close in terms of speed.

[Kurfürst]

Originally Posted by Sven

Would you say that with the data from that flight test that ~500 kmh could be achieved on the deck for a longer period of time in the BF109E without risking overheating ( which would happen only with emergency power of the 1-min WEP? ).

This trial: http://www.kurfurst.org/Performance_...w_109V15a.html

certainly suggest that it is so. They were running the plane at 1,31-1,33ata, and radiators were only 1/4 open (streamline position), yet coolant temperature could be maintained at constant 90 degrees Celsius, an optimum for the engine., so in practice it means that the aircraft should not overheat with the coolant in level flight and max power. (though it may reach somewhat higher temps in climbs).

The oil cooler was also closed (in practice its slightly open as it physically cannot close completely IIRC), yet oil temp remained at 62/82 Celsius. Its maintainable indefinietely for the 601A.

Of course the outside temperature during the test was somewhat low, at 5 Celius, so at higher temps we get somewhat higher temps, but not by much, and probably well within limit. The DB 601A could maintain a bit over 100 degrees Celsius coolant temperature indefinietely.

And is there a graph which shows us the maximum speed when the BF109E is using the 1-min WEP?

I have not seen one yet. But the performance is easily estimated with reasonable accuracy, as power requirements increase with the cube (ie. for 10% higher speed you need 33% more power). We know what the 109E did on the 5-min 1.35ata (497 km/h) and how much power 1.35 ata meant (1045 PS).

From that the 1-min 1.45ata (which gave 1175 PS, +12.44% power) is easy to calculate, that at +12.44% power the plane will be around 3.98% faster.

That's around 517 km/h at SL, on the 1-min WEP.

It seems the devs think that ~500 kmh on the deck ( 0m ) can only be achieved with use of this 1 min WEP, which is not what your German Data speed graph lets us believe, Kurfurst's 1.33/1.35 ATA versus 1C's WEP 1.4 ATA to achieve 500. Quite a difference in terms of aircraft modelling.

Yes, the 109E even with the patch will be still a little bit slow, but I think its much better than previously, when it was 40 km/h slower than it should be... I hope the devs will eventually find some time to polish it further. OTOH the serial produced planes had a certain tolerance.

One last thing, is this also a 'firewalled throttle without WEP' graph?

The 109E type specification sheet (http://kurfurst.org/Performance_test...chreibung.html) where is taken from does not say the power rating. However given the the results of the first test posted, which gave 497 km/h at 1.35ata, and this list 500 km/h, its 95% certain that this page is for the 5-min rating (1.35ata), and not including the boosted 1-min rating. Unless one wants to believe that +135 PS gave a speed boost of 3 km/h...

In short to make 'perfect' 109E model, it should make ~500 on the deck with 1.35, and ~515 with the 1-min WEP.

Coolant temperature should stay around 90 (indefinitely maintainable, ie. no overheat) at high speed flight with the radiator flaps 1/4 open, and oil temperature should stay around 60-80 Celsius with the oil cooler fully closed.

In addition, the radiator drag should be correctly modelled (I believe it does not given much if any drag on all planes in the current model). In reality fully opening it slowed down the plane by about 50 km/h - of course given the above, its a rather theoretical consideration, given that could perfectly maintain the aircraft cool in flight. The same was not the case on the ground however!

About the new Spitfire speed data, I don't want to see the SpitII replacing the Spit I on the servers, this should not be the solution. Dev team should look at 100 Octane SpitI speed figures which confirms that both the BF109E and SpitfireIa, if correctly modeled, are very close in terms of speed.

I absolutely agree, we need a +12 lbs version of the Spit I next to the existing 87 octane version. The Spit II I am afraid is correct, the type was limited to +9 lbs during the BoB, even with 100 octane, which meant 460-470ish top speed at SL, and was considerably slower than the +12 Spit I version or the 109E.

Originally Posted by 41Sqn_Banks

The Bf 109 can compensate it by unhistorical WEP.

What is so 'unhistorical' about it?

[fruitbat]

Originally Posted by Kurfürst

. The Spit II I am afraid is correct, the type was limited to +9 lbs during the BoB, even with 100 octane

I am genuinely intrigued by this, and not messing around, on what is that based?

I've seen this obviously, dated july 1940



and as Crump has pointed out in the other thread that all Spit MkII's were using 100 octane fuel in June 1940.

So what have you got that proves they were only on 9Lbs boost during BoB?

[41Sqn_Banks]

Originally Posted by Kurfürst

What is so 'unhistorical' about it?

According to the graph WEP is available in the game up to FTH, which is not correct. It was only authorized for take-off and up to 1-1.5km. So it's like the other take-off boosts which is shows in G50 or Blenheim graph, they should all only be available at low altitudes.
IIRC the DB601 manual also authorized the use only for overload conditions and short runways, not for regular take-off.

[Kurfürst]

Originally Posted by 41Sqn_Banks

According to the graph WEP is available in the game up to FTH, which is not correct. It was only authorized for take-off and up to 1-1.5km. So it's like the other take-off boosts which is shows in G50 or Blenheim graph, they should all only be available at low altitudes.

I know an easy fix for that, since the graph WEP shows performance which was achiveable without WEP in real life, simply rewrite the WEP line to Nominal in the FM.

Then add a new WEP line in the FM which is only useable for 1 min / ca 1.5 km and boost performance even further.

Things would be perffect then, and very historical.

IIRC the DB601 manual also authorized the use only for overload conditions and short runways, not for regular take-off.

I don't remember seeing such restriction. It would be strange in the DB manual anyways.

[41Sqn_Banks]

Originally Posted by Kurfürst

I know an easy fix for that, since the graph WEP shows performance which was achiveable without WEP in real life, simply rewrite the WEP line to Nominal in the FM.

Then add a new WEP line in the FM which is only useable for 1 min / ca 1.5 km and boost performance even further.

Things would be perffect then, and very historical.



I don't remember seeing such restriction. It would be strange in the DB manual anyways.

Note that "1 minute power" is only given "am Boden beim Abflug" (on ground for take-off) and not given for "in Bodennähe" (near ground level). There is nothing that indicates that "1 minute power" could be used up to FTH.

But I agree that the "5 minute power" at sea level is to slow for most of the presented post-patch graphs.

[fruitbat]

@Kurfurst, still waiting for your proof that all MKII's were limited to 9lbs from my post earlier,

Originally Posted by Kurfürst

. The Spit II I am afraid is correct, the type was limited to +9 lbs during the BoB, even with 100 octane

I am genuinely intrigued by this, and not messing around, on what is that based?

I've seen this obviously, dated july 1940



and as Crump has pointed out in the other thread that all Spit MkII's were using 100 octane fuel in June 1940.

So what have you got that proves they were only on 9Lbs boost during BoB?

[Kurfürst]

Originally Posted by fruitbat

@Kurfurst, still waiting for your proof that all MKII's were limited to 9lbs from my post earlier,

I am genuinely intrigued by this, and not messing around, on what is that based?

I have posted this paper (and of course I got it from someone else). But others (I think 41 Banks) have pointed out that this page was amended, given the amendment no, likely in 1941 IIRC. So in short the +12 limit only appears in later manuals, but the 1940 ones.

The unamended (likely first or early) version from July 1940 shows the limit as +9 for 5 min Combat (+12 is enabled, but only for take off for a limited time/altitude).