Dora climb rates

[MiloMorai]

So what we have is the best for the D-9 and the average for other a/c.

 

I don't know where this 11% comes from as:

26/22.9 x 100 = 113.5%

27/22.9 x 100 = 117.9%

28/22.9 x 100 = 122.3%

[Pilum]

 

Pretty smart if you think about it. The customer buys off on the lower estimate and is thrilled when they get the finished product. Might even make the designer an honorary title and allow his name to be used as an official aircraft designation!!

 

ROTFL :megalol:

[Crumpp]

I don't know where this 11% comes from as:

 

 

Read what Yo-Yo posted....

 

26/22.9 x 100 = 113.5%

27/22.9 x 100 = 117.9%

28/22.9 x 100 = 122.3%

 

22.9% is the bottom of the range. So 122.3% - 100 = 22.3%

 

22.3%-10% = The average performance is 12.3% higher than the 22.9.

 

22.9 x 1.123 = 25 m/s

 

28/25 = 11%

[MiloMorai]

disregard for now

Edited March 8, 2015 by MiloMorai

[Crumpp]

Wouldn't the graphic posted in Post #89 mean +/- 3% and +/- 10%?

 

Where does this 20% mentioned come from?

 

You do understand that is a range?

 

+ or - 10% is a range of 20%....

 

https://www.mathsisfun.com/data/range.html

[Kwiatek]

I just wonder how D-9 at 1.8 Ata could have much better climb rate then IRL 109 K-4 at 1.8 Ata.

 

IRL data K-4 got better climb rate then D-9 which is nothing strange casue it got better power to weight ratio with MW 50 power settings.

 

D-9 - 2100 HP/ ~4200 kg - 0.5 HP/Kg

K-4 - 1850 HP/ ~3400 kg - 0.54 Hp/Kg.

 

K-4 best climb rate at 1.8 ata was 24,5 m/s. D-9 should be below these.

[MiloMorai]

disregard for now

 

So if 426mph is the minimum max speed, then 3% plus another 3% needs to added to the 426.

 

426x 1.03 = 439mph

426x 1.06 = 452mph

 

Does the D-9 reach 452mph (727kph) in game?

 

Now 452mph is the max speed one usually sees for the K-4 but if 3% plus 3% is added to that 452 one gets the K-4 topping out at 478mph (769kph).

 

It also means the DCS P-51 should be topping out at 463mph, which it isn't in game.

[MiloMorai]

You do understand that is a range?

 

+ or - 10% is a range of 20%....

 

https://www.mathsisfun.com/data/range.html[/quote

 

Really. Didn't know that, thanks.

[Pilum]

I just wonder how D-9 at 1.8 Ata could have much better climb rate then IRL 109 K-4 at 1.8 Ata.

 

IRL data K-4 got better climb rate then D-9 which is nothing strange casue it got better power to weight ratio with MW 50 power settings.

 

D-9 - 2100 HP/ ~4200 kg - 0.5 HP/Kg

K-4 - 1850 HP/ ~3400 kg - 0.54 Hp/Kg.

 

K-4 best climb rate at 1.8 ata was 24,5 m/s. D-9 should be below these.

 

I agree and that is a good point. In fact it looks like both the Dora and K4 have too high climb rate right now in DCS: A thread was started on the K4 which showed an initial climb rate of 6100 fpm or circa 31 m/s.

 

http://forums.eagle.ru/showthread.php?t=137503

 

However, the difference is that the K4's excessive climb rate thread has been closed and confirmed to be a bug:

 

http://forums.eagle.ru/showpost.php?p=2292272&postcount=85

[Crumpp]

I just wonder how D-9 at 1.8 Ata could have much better climb rate then IRL 109 K-4 at 1.8 Ata.

 

IRL data K-4 got better climb rate then D-9 which is nothing strange casue it got better power to weight ratio with MW 50 power settings.

 

D-9 - 2100 HP/ ~4200 kg - 0.5 HP/Kg

K-4 - 1850 HP/ ~3400 kg - 0.54 Hp/Kg.

 

K-4 best climb rate at 1.8 ata was 24,5 m/s. D-9 should be below these.

 

Look at the power characteristics of the Jumo 213A...

 

The Dora does not outclimb the Bf-109K4.

[Crumpp]

I agree and that is a good point. In fact it looks like both the Dora and K4 have too high climb rate right now in DCS: A thread was started on the K4 which showed an initial climb rate of 6100 fpm or circa 31 m/s.

 

http://forums.eagle.ru/showthread.php?t=137503

 

However, the difference is that the K4's excessive climb rate thread has been closed and confirmed to be a bug:

 

http://forums.eagle.ru/showpost.php?p=2292272&postcount=85

 

When Yo-Yo say's the Dora's climb rate is NOT a bug...you have issues?

 

When the math backs up Yo-Yo's conclusions....

 

You have issues.

 

I would say the burden of proof is on you.

[sobek]

Mind your manners, guys. You all know the drill by now.

[Yo-Yo]

I agree and that is a good point. In fact it looks like both the Dora and K4 have too high climb rate right now in DCS: A thread was started on the K4 which showed an initial climb rate of 6100 fpm or circa 31 m/s.

 

http://forums.eagle.ru/showthread.php?t=137503

 

However, the difference is that the K4's excessive climb rate thread has been closed and confirmed to be a bug:

 

http://forums.eagle.ru/showpost.php?p=2292272&postcount=85

 

Could you please write down the equation you use for Vy calculation?

[Crumpp]

So if 426mph is the minimum max speed, then 3% plus another 3% needs to added to the 426.

 

426x 1.03 = 439mph

426x 1.06 = 452mph

 

Does the D-9 reach 452mph (727kph) in game?

 

Now 452mph is the max speed one usually sees for the K-4 but if 3% plus 3% is added to that 452 one gets the K-4 topping out at 478mph (769kph).

 

It also means the DCS P-51 should be topping out at 463mph, which it isn't in game.

 

No it does not work this way. If you look at the published performance, the percentage represents the distance from the average.

 

426x 1.03 = 439mph

 

But not always. That is up to the manufacturer. What appears to be the case is Focke Wulfs internal performance estimates represent the lower end of the range as minimum performance.

 

The climb rate using what is called "Top of the Climb" at 6Km on the November 1944 Kennblatt shows 15m/s for a 4350Kg aircraft at normal climb rating. In June 1944 Focke Wulf reported to the RLM the design was expected to only achieve a 12.8 m/s at normal climb rating at a top of the climb to 5.8Km.

 

First of all you have to understand what that means. 15 m/s is not the "average" climb rate. That is the climb rate from sea level to the altitude defined as the top of the climb to achieve our time to climb curve.

 

The June of 1944 performance is far below the November of 1944 kennblatt.

[Pilum]

When Yo-Yo say's the Dora's climb rate is NOT a bug...you have issues?

 

When the math backs up Yo-Yo's conclusions....

 

You have issues.

 

I would say the burden of proof is on you.

 

Yes, I do have issues with your calculations since these show climb rates that are way higher than those calculated by Focke-Wulf. And no, the burden is not on me but on you, since I rely on numbers calculated by Abteilung Flugmechanik-L at Focke-Wulf and you rely on calculations that are by your own admission SWAG's.

[Pilum]

Could you please write down the equation you use for Vy calculation?

 

Sorry can't do that since it is in the C++ code in a number of different function that are called upon to estimate prop and exhaust thrust, parasite and induced drag all as functions of altitude, mach etc. Basically I numerically iterate different climb angles and speeds until I find the optimum.

[Yo-Yo]

Sorry can't do that since it is in the C++ code in a number of different function that are called upon to estimate prop and exhaust thrust, parasite and induced drag all as functions of altitude, mach etc. Basically I numerically iterate different climb angles and speeds until I find the optimum.

 

Anyway, it could be very interesting what basic values calculates your code for sea level for 3000 rpm and 3250 MW-50.

 

 

It's very interesting fact: for 3000 rpm as I use jet thrust for Vy estiimation - I get TEST FLIGHT Vy curve. As I null this thrust - I get German estimations you referred to as "real curves".

[Crumpp]

It's very interesting fact: for 3000 rpm as I use jet thrust for Vy estiimation - I get TEST FLIGHT Vy curve. As I null this thrust - I get German estimations you referred to as a "real curves".

 

 

 

So without exhaust thrust your results match the Flugmechanik estimate.

[Pilum]

Yo-Yo: So are you saying that the Focke-Wulf figures are without exhaust thrust?

[Yo-Yo]

Yo-Yo: So are you saying that the Focke-Wulf figures are without exhaust thrust?

 

All evidences are for it. I did not see the figures in the initial calculations.

 

If I switch off jet thrust I get http://www.wwiiaircraftperformance.org/fw190/fw190d9-climbchart-flugmechanik-24-3-45.jpg

 

1 and 3

Edited March 8, 2015 by Yo-Yo

[Pilum]

All evidences are for it. I did not see the figures in the initial calculations.

 

Well the Focke-Wulf estimated climb rate is around 22 m/s for 1.8 ata as far as I can tell. If it goes up to 28 m/s (or do you have another estimate?) if exhaust thrust is added, why on earth would Focke-Wulf publish a chart showing 22 m/s climb rate without this included when it would go up to 28 m/s with exhaust thrust accounted for?

[Crumpp]

why on earth would Focke-Wulf publish a chart showing 22 m/s climb rate without this included when it would go up to 28 m/s with exhaust thrust accounted for?

 

Probably because Junkers did not provide an estimate to them.

 

The power curves in the report simply show thrust horsepower expected from the engine. Basically, you are looking at a rough performance estimate and concluding that the aircraft was not developed beyond that point.

Edited March 8, 2015 by Crumpp

[Pilum]

Probably because Junkers did not provide an estimate to them.

 

The power curves in the report simply show thrust horsepower expected from the engine. Basically, you are looking at a rough performance estimate and concluding that the aircraft was not developed beyond that point.

 

So are you saying that you would estimate that adding exhaust thrust would add 6 m/s? i.e. lift the Focke-Wulf figure of 22 to 28 m/s in climb?

[Crumpp]

No Pilum..

 

I am saying if Junkers was conservative in their power estimate, Focke Wulf conservative in their performance estimate, and exhaust thrust was not included then you will see a significant improvement over the estimate.

 

That is why the margin of performance error is larger for new type aircraft.

[Pilum]

No Pilum..

 

I am saying if Junkers was conservative in their power estimate, Focke Wulf conservative in their performance estimate, and exhaust thrust was not included then you will see a significant improvement over the estimate.

 

That is why the margin of performance error is larger for new type aircraft.

 

Ok you have a lot of "if's" there. Does that mean that in your opinion the reason for the difference between DCS and the Focke-Wulf data is due the compound effect of a low estimate by Junkers coupled with a low estimate by Focke-Wulf and no exhaust thrust added which leads to the 6 m/s difference in climb speed? Why ever would they publish such a chart and make no mention whatsoever of these assumptions?

 

But if not 6 m/s then how large is this "significant improvement"? Your SWAG was 28 m/s and Focke-Wulf's is 22 m/s so the difference there is 6 m/s. If it's not 6 m/s then what what is the actual climb rate of the Dora at 1.8 ata, i.e. the one we should expect to see in DCS without conservative estimates by Junkers and Focke-Wulf and WITH exhaust thrust included?

Edited March 8, 2015 by Pilum