Su-27 in-game climb performance, v2.5.6

[Cmptohocah]

Did some flight testing of my own inside DCS of the Su-27's climb performance:

Environment: 20deg OAT, 1013hPa

Load out: 2 x R-73, 2 x R-27R

Weight: 26.583kg (90% fuel)

Altitudes: 1000m and 5000m MSL, respectfully

Seems that at:

• 1000m alt Vy (best rate-of-climb) is around 700km/h IAS and Vx (best angle-of-climb) is around 450km/h
• 5000n alt Vy (best rate-of-climb) is around 650km/h IAS and Vx (best angle-of-climb) is around 580km/h

Edited February 12, 2021 by Cmptohocah
Forum editor sucks

[Hodo]

Good tests.  But is there an issue with these numbers?  I haven't had a real good chance to compare to any data I have on the 27 at home.  

 

And you are absolutely right about the forum editor.

[BBCRF]

замерять надо при массе топлива 2650 кг

[Cmptohocah]

24 minutes ago, BBCRF said:

замерять надо при массе топлива 2650 кг

No problem, I will also do the tests with this fuel load. 

[Cmptohocah]

2 hours ago, Hodo said:

Good tests.  But is there an issue with these numbers?  I haven't had a real good chance to compare to any data I have on the 27 at home.  

 

And you are absolutely right about the forum editor.

There is a strange dip that happens on both altitudes around 600km/h, which is quite strange. Also while testing, I was under the impression that there is quite strange behaviour in general, but I can't put my finger on it.

[Ironhand]

No

t sure exactly what you're trying to figure out but...

 

Are you aware of this from the RW manual?

Quote

5.4.2. The afterburner flight program is executed at full afterburner until completion of the attack using one of the following profiles:

·         Takeoff and climb to 11,000 m at Mach 0.9-0.95 (positions 1-2-3);

·         Once at an altitude of 11,000 m, acceleration to Mach 1.3, 1.8, 2.0. M 2.0 is accomplished by accelerating to IAS (Vпр) = 1200 km/h, then by climbing at a constant IAS (Vпр) = 1200 km/h until reaching M = 2.0;

·         Climb at Mach 0.9, 1.3, 1.8, 2.0 to position д-е, а-б, в-г, or 5-6 and fly until the command “Vertical” (climb/descend toward the target) is received [climb at Mach 0.9, if a climb at Full Military Power (МАКСИМАЛ) is preferred]

·         Level out at the target attack altitude after fulfilling the “Vertical” command prior to the homing stage.

 

5.4.3. A non-afterburning flight program for intercepting aerial targets is used to maximize the intercept range and is performed according to the following profile:

·         Take off at Full Military Power (MAXIMAL mode) and climb to 11,000 m at TAS (Vист) = 860 km/h

·         Accelerate to Mach 0.9, then climb and cruise at Mach 0.9 (cruising-climb flight) until given the command “Vertical”.

 

 

 

[Cmptohocah]

@BBCRF here is the plot for 2650kg (29%) of fuel:

Seems to be nearly identical to the one above, in terms of curve shape and air speeds at which the peak of the climb rate happens.
Note: value at 300km/h for 5000m altitude has been added there to make the shape of the curve look nicer.

15 hours ago, Ironhand said:

No

t sure exactly what you're trying to figure out but...

 

Are you aware of this from the RW manual?

 

 

 

Hi @Ironhand,

and thanks for sharing the manual info.

The purpose of this research is to show the actual flight performance (in this case climb) of the Su-27 within DCS it self. I always like to know what exactly I am dealing with and these graphs help in illustrating just that.

[Cmptohocah]

15 hours ago, Ironhand said:

Once at an altitude of 11,000 m, acceleration to Mach 1.3, 1.8, 2.0. M 2.0 is accomplished by accelerating to IAS (Vпр) = 1200 km/h, then by climbing at a constant IAS (Vпр) = 1200 km/h until reaching M = 2.0;

 

 

 

Is the value 1200km/h supposed to be TAS instead of IAS? Seems that at 11km altitude that 1200km/h IAS is around 2.2M.

[BBCRF]

1 hour ago, Cmptohocah said:

@BBCRF вот график на 2650кг (29%) топлива:

Кажется, что он почти идентичен приведенному выше с точки зрения формы кривой и скорости воздуха, при которых происходит пик скорости набора высоты.
Примечание: сюда добавлено значение 300 км / ч для высоты 5000 м, чтобы форма кривой выглядела лучше.

Здравствуй @Ironhand,

и спасибо, что поделились информацией из руководства.

Цель исследования - показать фактические летно-технические характеристики (в данном случае набор высоты) Су-27 в самой DCS. Мне всегда нравится знать, с чем именно я имею дело, и эти графики помогают проиллюстрировать это.

надо делать замер по высотам 1000м 3000м 5000м  11000м , скорость при этом выдерживать 0,85-0,9М, а на 11000м 1,4-1,6М

[Ironhand]

3 hours ago, Cmptohocah said:

Is the value 1200km/h supposed to be TAS instead of IAS? Seems that at 11km altitude that 1200km/h IAS is around 2.2M.

Not according to the manual. I suppose it’s possible that I’m in error but the manual states “Vпр“.

 

EDIT: It does say to climb at 1200km/hr until reaching M 2.0

Edited February 14, 2021 by Ironhand

[BBCRF]

18 minutes ago, Ironhand said:

Не по инструкции. Полагаю, возможно, я ошибаюсь, но в инструкции написано « Vпр ».

 

Vпр- это приборная скорость IAS

[Ironhand]

1 hour ago, BBCRF said:

Vпр- это приборная скорость IAS

Thank you.

[DarkFire]

Very useful information, thanks for taking the time to record & post this.