[REPORTED] underperforming engine

I did a trial at sea level to see how does engine performance match the performance charts and I have found out that A8 is underperforming in DCS.

 

I have used manual rpm control as auto did not allow for proper power settings.

Test were done at 4300kg and w/o pylon

 

2300/1.2 - DCS: 480 - RL: ~507

2400/1.32 - DCS: 511 - RL: ~532

2700/1.42 - DCS: 537 - RL: ~557

 

 

It looks like in DCS A8 is around 20km/h too slow at sea level.

I did a trial at sea level to see how does engine performance match the performance charts and I have found out that A8 is underperforming in DCS.

 

I have used manual rpm control as auto did not allow for proper power settings.

Test were done at 4300kg and w/o pylon

 

2300/1.2 - DCS: 480 - RL: ~507

2400/1.32 - DCS: 511 - RL: ~532

2700/1.42 - DCS: 537 - RL: ~557

 

 

It looks like in DCS A8 is around 20km/h too slow at sea level.

 

on this charts speeds is TAS right ?? not IAS

i managed to hit 547 tas at full throttle still a little too slow

Edited June 15, 2019 by grafspee

That doesn't matter at sea level. IAS and TAS are about the same at this altitude. The rule of thumb is to ad 2% to your IAS per 1000ft of altitude to get your estimated TAS.

 

 

MadCat

grafspee, yes TAS. Also note in screenshots that I used info bar with TAS.

That doesn't matter at sea level. IAS and TAS are about the same at this altitude. The rule of thumb is to ad 2% to your IAS per 1000ft of altitude to get your estimated TAS.

 

 

MadCat

 

its amtter becouse recently we got preaty big IAS error

grafspee, yes TAS. Also note in screenshots that I used info bar with TAS.

 

ok i noticed it just now heh :P

Edited June 15, 2019 by grafspee

max what i managed to do

it took me good 3-4 minutes to climb above 540kph

it is still more then 10kph slower then numbers on charts :P

i would like to know if those numbers on charts are normalized to standard atm and temp if not engine can squize couple hp more in clod air and higher atm pressure

how fast p-51 shoudl go ?? at sea level i managed to do 587kph p-51D-15 had top speed 603kph at 67" wow almot 20kph slower is all warbirds have this in dcs ??(603kph with bomb racks instaled)

Edited June 15, 2019 by grafspee

That doesn't matter at sea level. IAS and TAS are about the same at this altitude. The rule of thumb is to ad 2% to your IAS per 1000ft of altitude to get your estimated TAS.

I recently had to debunk that "myth" in another thread. No, TAS doesn't match IAS at sea level, it does at International Standard Atmosphere values (ISA) conditions (1013hP, 15ºC), otherwise not only it doesn't match, TAS can be either higher than IAS (what most people expect) or lower depending on temperature and pressure. So it matters, really matters, what conditions did you make the test.

 

 

On the other hand, IIRC German tests weren't standardised or at least weren't in a modern standard (ISA conditions) so you don't even know in what conditions those charts were taken, and you don't know what conditions you took yours. In the end you're comparing apples and oranges.

 

 

S!

Edited June 15, 2019 by Ala13_ManOWar

ISA was introduced in 1952. Everyone was using different reference models before that.

 

The reference models I am aware of (ICAN and the USA one) were very close in practice so it probably doesn't matter. The Germans had the same reference atmosphere as the UK and Italy before the war.

These charts (calculated) of 1943 were too optimistic.

Later the data was more realistic:

 

http://www.wwiiaircraftperformance.org/fw190/leistungsdaten-1-10-44.jpg

 

The same graph of Flugmechanik from 25/10/44 shows 544 kph for 1/42/2700, 4300 kg, without ETC 501 and 565 for 1.58 ata.

 

http://www.wwiiaircraftperformance.org/fw190/fw190-a8-25oct44.jpg

OK, I made now tests at 0, 2, 4, 6km and plotted on the graph you have provided.

 

 

I would not agree that Germans did not reduce test results to ISA

I guess back then they had to know what standard they were using, though I don't know since charts don't say. IIRC it's been discussed in these forums back in time how German standard was a bit not standard at all and it was tricky to compare direct results to those without knowing what conditions did they took the tests, mostly at Rechlin. Did you get new information on that respect since last time? How was the German standardisation method?

 

 

 

S!

Hello,

 

 

May be I am off topic, but historical approach may also be considered in a ww2 simulation.

 

Charts given by test measurements with protocols give features from aircraft in a very good condition.

In operation, on the front airbase, what were aircraft conditions ? Many of them were in a certain degree of wearing, some of them had been repaired … well not all aircrafts were in the same condition.

Depending on the context some of the aircrafts were quite far from their original performance.

 

 

Belly

Is there a chance of getting the BMW801D-2 with 1,58/1,65ata manifold pressure? I think this would solve the acceleration Problem (as shown in the diagram)

May be I am off topic, but historical approach may also be considered in a ww2 simulation.

 

Charts given by test measurements with protocols give features from aircraft in a very good condition.

In operation, on the front airbase, what were aircraft conditions ? Many of them were in a certain degree of wearing, some of them had been repaired … well not all aircrafts were in the same condition.

Depending on the context some of the aircrafts were quite far from their original performance.

This would been acceptable if all planes followed such pattern. Indicating that only Germans did not know how to maintain their planes is a bit too stretched fantasy (I am not saying that you are implying it).

P51 and Spit perf in DCS are within 1% error for max setting while A8 is much worse and that is not right.

Personally I am not about hitting every number square on, however relative performance must be in check for realistic PvP to work.

 

ED has shown with other planes that they can do it, so I am optimistic that A8 will get some love in performance details...

Hello,

 

 

May be I am off topic, but historical approach may also be considered in a ww2 simulation.

 

Charts given by test measurements with protocols give features from aircraft in a very good condition.

In operation, on the front airbase, what were aircraft conditions ? Many of them were in a certain degree of wearing, some of them had been repaired … well not all aircrafts were in the same condition.

Depending on the context some of the aircrafts were quite far from their original performance.

 

 

Belly

we can assume that all sides were operating aircrafts at difrent condition so we can rule it out just to make it easier to simulate.

another thing is that like almost all trial tests done by manufactures of planes did at brand new conditions so we porbably dont have any hard data about preformance of weared planes.

we could add numerous individual modifications done by pilots or by ground crews that plane could outperform his brand factory new brother

i think this topic is way to deep.

Let focus on brand new planes

this thing can be applied to all planes and vechicles and ships not only for ww2 stuf but for modern too

Edited June 16, 2019 by grafspee

I took a few values.

 

 

Atmosphere:

760mmHg

15°C

no wind or turbulences

 

 

Clean aircraft. Takeoff weight under 4100kg.

 

 

Around 3000m altitude the 2nd stage of the charger kicks in. This leads to a significant power loss.

 

 

I managed to fly with Max cont. pwr and Climb pwr setting at 3000m both in the 1st stage as well as in the 2nd stage.

 

MCP with 1st stage(1.08ata) -> 535km/h, with 2nd stage(1.20ata) ->511km/h

Climbpower with 1st stage(1.12ata) -> 552km/h, with 2nd stage(1.32ata) ->531km/h

 

 

Although the pressure is less with the 1st stage at 3000m, the resulting speed is significant higher.

 

 

Fox

 

 

 

I took a few values.

 

 

Atmosphere:

760mmHg

15°C

no wind or turbulences

 

 

Clean aircraft. Takeoff weight under 4100kg.

 

 

Around 3000m altitude the 2nd stage of the charger kicks in. This leads to a significant power loss.

 

 

I managed to fly with Max cont. pwr and Climb pwr setting at 3000m both in the 1st stage as well as in the 2nd stage.

 

MCP with 1st stage(1.08ata) -> 535km/h, with 2nd stage(1.20ata) ->511km/h

Climbpower with 1st stage(1.12ata) -> 552km/h, with 2nd stage(1.32ata) ->531km/h

 

 

Although the pressure is less with the 1st stage at 3000m, the resulting speed is significant higher.

 

 

Fox

 

 

 

 

this corelation higher ATA = higher speed only works withing certain supercharger speed

its not working across 1st and 2nd superchasrger speed

when you comparing end of 1st stage to begining of 2nd its like comaring best case scenario to worst case scenario

Edited June 16, 2019 by grafspee

this corelation higher ATA = higher speed only works withing certain supercharger speed

its not working across 1st and 2nd superchasrger speed

when you comparing end of 1st stage to begining of 2nd its like comaring best case scenario to worst case scenario

Please explain how a low pressure can produce more poweroutput of the engine than a high pressure. Why use the 2nd stage, if the 1st stage produces more power?

 

 

Fox

Please explain how a low pressure can produce more poweroutput of the engine than a high pressure. Why use the 2nd stage, if the 1st stage produces more power?

 

 

Fox

 

1st and 2nd speed has difrent compression ratio those 1st speed will heat up air less then 2nd speed(higher air temp = less density = less oxygen in given volume = less power) aditonal to this 2nd speed require more power from crank shaft to be spined

look at every power chart for engines from warbirds using multiple speed superchargers.

here you can see power charts for low and high blower for v-1650-7 running 75" boost

check power for 75" at 3200ft low blower is hitting over 1900hp and at exact the same 75" boost high blower bearly hitting 1600hp now you can cross both power curves and they meet around 8k ft alt where low blower is boosting only 62" and have same power as engien running high blower at 75"(it is almost 13" difrence in boost which translate to 0.43ATA) so perfect switch for high blower would be around 8k ft for this engine.

take note that p-51's engine has inter stage cooling in supercharger and aftercooler which probably is helping high blower a lot without it high blower would lag even more behind low blower speed power curve.

i dont know how looks fw190 a8 supercharger system i know that it is 2 speed single stage supercharger i dont know anything about aftercooling or anything instaled in fw190

if you look at power for 15k ft its clear win for high blower

small tip if you want go for super economy in warbirds like spitfire or p-51 where you can force 1st speed you just go climb very high and stay on low blower speed it will give you extreme range

Edited June 19, 2019 by grafspee

I feel the Fw190 is also underperforming in speed and climb... I am wondering though if it is linked to Kommandogerat, which doesn't seem quite right to me. I don't know enough of the technical details to confirm or deny, but you do seem to know more.

I feel the Fw190 is also underperforming in speed and climb... I am wondering though if it is linked to Kommandogerat, which doesn't seem quite right to me. I don't know enough of the technical details to confirm or deny, but you do seem to know more.

 

im only saying that is possible to happen i dont know how is done in fw190 and how kommandogerat works

1st and 2nd speed has difrent compression ratio those 1st speed will heat up air less then 2nd speed(higher air temp = less density = less oxygen in given volume = less power) aditonal to this 2nd speed require more power from crank shaft to be spined

look at every power chart for engines from warbirds using multiple speed superchargers.

here you can see power charts for low and high blower for v-1650-7 running 75" boost

check power for 75" at 3200ft low blower is hitting over 1900hp and at exact the same 75" boost high blower bearly hitting 1600hp now you can cross both power curves and they meet around 8k ft alt where low blower is boosting only 62" and have same power as engien running high blower at 75"(it is almost 13" difrence in boost which translate to 0.43ATA) so perfect switch for high blower would be around 8k ft for this engine.

take note that p-51's engine has inter stage cooling in supercharger and aftercooler which probably is helping high blower a lot without it high blower would lag even more behind low blower speed power curve.

i dont know how looks fw190 a8 supercharger system i know that it is 2 speed single stage supercharger i dont know anything about aftercooling or anything instaled in fw190

if you look at power for 15k ft its clear win for high blower

small tip if you want go for super economy in warbirds like spitfire or p-51 where you can force 1st speed you just go climb very high and stay on low blower speed it will give you extreme range

 

THX for your effort.