how to reach the max speed ?

[Lenux]

I want to reach the max speed with SU27 ( 2500 kmph ) without dogfight / missions / online. Just testing ....

How could i do that ?Do i have to fly very high ? Is that possible, at all ??

Thank you in advance

[razo+r]

No loadout and at around 12km height and a long waiting time...

[Lenux]

what do you mean by " a long waiting time" ?

[TheKrayTwin]

It takes a while to accelerate to maximum speed. I would take fuel tanks and drop them at the 12km height. Set auto pilot, engage full throttle, and go make a cup of tea.

[DarkFire]

Except the Su-27 doesn't carry tanks :)

 

There are 2 ways to do it:

 

1) Use the mission editor to place yourself at high altitude and high speed. Jump in to the cockpit, trim, stabilise the aircraft, engage altitude hold mode on the ACS and hit the burners. Eventually you'll reach maximum speed.

 

2) From the runway. Take off using dry thrust. After takeoff level off at low level until your speed is between M0.85 and M0.9. Pull up to somewhere between 12 and 15 degrees pitch and climb with vertical velocity between 50 and 75 m/s until you reach about 6,000m altitude. At that point bring your vertical velocity down to 35-40 m/s until you reach ~8,000m altitude. At this point bring your vertical velocity down to between 20 - 25 m/s until you reach 10,000m altitude. At this point you should have roughly 8,200Kg of fuel remaining.

 

Level off at 10K and engage the afterburner until you're at ~M1.2. Climb to between 13,000 - 14,000m ensuring that your IAS never falls below 560 Km/h, which is shouldn't do in maximum AB. Finally, level off at 13,500m, hit altitude hold and wait.

 

For a 'standard' DCS day with a completely clean configuration the Su-27 will eventually reach M2.55 - M2.60 which is significantly faster than it should go, but it is fun being that fast :)

 

Note that you'll only hit absolute Vmax between 13,000 - 13,500m altitude during a standard DCS day.

[Sheepherder]

I want to reach the max speed with SU27 ( 2500 kmph ) without dogfight / missions / online. Just testing ....

How could i do that ?Do i have to fly very high ? Is that possible, at all ??

Thank you in advance

 

The 2500 km/h number given in the editor and Wikipedia is in ground speed in the cockpit you will never see a number that high, because your instruments relay mach number and indicated airspeed.

[Lenux]

Sheepherder, I'm confused now

I just came home 15 min ago and i wanted to give it a try, but after i read your post, as I said, i'm confused

Edited August 8, 2016 by Lenux

[razo+r]

Just watch in outside view or on the MACH indicator

[DarkFire]

The 2500 km/h number given in the editor and Wikipedia is in ground speed in the cockpit you will never see a number that high, because your instruments relay mach number and indicated airspeed.

 

The HDD on the Su-27 shows TAS, which will approach that number. I forget now what it shows at ~M2.6 but IIRC it's above 2,000 Km/h.

 

Edited to add: I was wrong. Max speed is attained at around 12,000m altitude, but in reality the difference in Vmax over the range 11,000 - 14,000m altitude is so little that it makes no practical difference.

 

Attached is an example track file and ACMI recording. Tacview reports maximum speed at 13,500m altitude (as per the HUD, actual altitude was around 13,950m) was 2,759 Km/h which equated to Mach 2.60. I believe that the TAS shown on the HDD was 2,750 Km/h.

 

For the test I took off from Krymsk and landed at Soganlug 28 minutes later, with a distance flown of ~690Km.

 

For a speed v altitude profile for the Su-27, see this thread:

 

http://forums.eagle.ru/showthread.php?t=165967

Edited August 9, 2016 by DarkFire

[Lenux]

Thank you, DarkFire

[Sheepherder]

The HDD on the Su-27 shows TAS, which will approach that number. I forget now what it shows at ~M2.6 but IIRC it's above 2,000 Km/h.

 

Edited to add: I was wrong. Max speed is attained at around 12,000m altitude, but in reality the difference in Vmax over the range 11,000 - 14,000m altitude is so little that it makes no practical difference.

 

Attached is an example track file and ACMI recording. Tacview reports maximum speed at 13,500m altitude (as per the HUD, actual altitude was around 13,950m) was 2,759 Km/h which equated to Mach 2.60. I believe that the TAS shown on the HDD was 2,750 Km/h.

 

For the test I took off from Krymsk and landed at Soganlug 28 minutes later, with a distance flown of ~690Km.

 

For a speed v altitude profile for the Su-27, see this thread:

 

http://forums.eagle.ru/showthread.php?t=165967

 

Fair cop: before you posted I ran it up to about Mach 2.5 at 12 500 m, but apparently the HUD and steam gauges reads IAS and the HDD reads TAS and the F2 view reads GS.

 

In any case, if you're doing something in the ballpark of mach 2.4 - 2.6 @ 12 - 14 k you're probably reaching the upper limit on speed no matter how you slice it.

[DarkFire]

Yep, definitely.

 

It'd be nice if ED could add some explanation text to the info bar at the bottom of the screen in external views to make it obvious that the readings are GS and not IAS or TAS and ASL rather than AGL etc.

[Yo-Yo]

For a 'standard' DCS day with a completely clean configuration the Su-27 will eventually reach M2.55 - M2.60 which is significantly faster than it should go, but it is fun being that fast :)

 

 

The plane SHOULD go that fast, but its canopy and, possibly, some airframe parts can not withstand Mach heating. So, the 2.5M or whatever is written in the books is only a never exceed Mach.

[DarkFire]

The plane SHOULD go that fast, but its canopy and, possibly, some airframe parts can not withstand Mach heating. So, the 2.5M or whatever is written in the books is only a never exceed Mach.

 

That would make sense. The translated Su-27 manual that's floating around the internet states something like 'speed above 2.0M - not more than 5 minutes' for exactly the reason you mentioned. Fair enough that it can aerodynamically go faster than that, I suppose the often quoted maximum speed figure of 2.35M may be the 'official safe figure' like the F-15C having a quoted maximum speed of 2.5M whereas it's actually been flown to 2.7M.

 

Thanks for the insight :)

[ShuRugal]

Except the Su-27 doesn't carry tanks :)

 

There are 2 ways to do it:

 

1) Use the mission editor to place yourself at high altitude and high speed. Jump in to the cockpit, trim, stabilise the aircraft, engage altitude hold mode on the ACS and hit the burners. Eventually you'll reach maximum speed.

 

2) From the runway. Take off using dry thrust. After takeoff level off at low level until your speed is between M0.85 and M0.9. Pull up to somewhere between 12 and 15 degrees pitch and climb with vertical velocity between 50 and 75 m/s until you reach about 6,000m altitude. At that point bring your vertical velocity down to 35-40 m/s until you reach ~8,000m altitude. At this point bring your vertical velocity down to between 20 - 25 m/s until you reach 10,000m altitude. At this point you should have roughly 8,200Kg of fuel remaining.

 

Level off at 10K and engage the afterburner until you're at ~M1.2. Climb to between 13,000 - 14,000m ensuring that your IAS never falls below 560 Km/h, which is shouldn't do in maximum AB. Finally, level off at 13,500m, hit altitude hold and wait.

 

For a 'standard' DCS day with a completely clean configuration the Su-27 will eventually reach M2.55 - M2.60 which is significantly faster than it should go, but it is fun being that fast :)

 

Note that you'll only hit absolute Vmax between 13,000 - 13,500m altitude during a standard DCS day.

 

 

when I used to play on 104th a lot (before the R-27 got it's guidance package removed), I would use a climb profile similar to method 2 and generally ended up at 12km and ~ mach 1.5 with 8 tons of fuel remaining. With a long enough ingress time, i've occasionally managed to enter engagements at mach 2-2.3.

 

Of course, doing that now just means that you'll run into the SPAMRAAM barrier that much sooner, without giving any usable advantage to your own missiles.

[DarkFire]

when I used to play on 104th a lot (before the R-27 got it's guidance package removed), I would use a climb profile similar to method 2 and generally ended up at 12km and ~ mach 1.5 with 8 tons of fuel remaining. With a long enough ingress time, i've occasionally managed to enter engagements at mach 2-2.3.

 

Of course, doing that now just means that you'll run into the SPAMRAAM barrier that much sooner, without giving any usable advantage to your own missiles.

 

Interesting, I haven't tried it yet with a full A-A war load. Stand by...

 

OK, here we go. I had to adjust my climb profile slightly to account for the extra ~2,500Kg of weapons. Essentially I had to lower my vertical velocity by 5-10 m/s per climb 'stage' but the end effect was largely the same.

 

I ended up at M2.38 at just over 12,000m altitude. Fuel usage was significantly higher, to the point that this time I failed to make it to Soganlug and had to land at Krymsk instead. Acceleration to the max speed was also significantly lower. :ermm: :disgust:

 

Edited to add: Was I drunk when I wrote that last sentence??? I meant that acceleration was lower.

 

Track and ACMI attached.

Edited August 13, 2016 by DarkFire