SU25T general performance

[Idle_Wild]

The aerobatic performance of this aircraft can't be modelled accurately, surely?

 

I've just downloaded the latest version of DCS 1.5, and have attempted to familiarise myself with the SU-25T, I have never flown fast jets, but it's like flying a lead-brick.

 

With the pylons completely empty, it has no maneuvering ability, if I attempt a medium level turn at 30 degrees of bank, with more than a fraction of back-pressure on the stick, and combined rudder pressure, the stall warning goes off, and I get either a wing-drop on the inside-turning wing or a completely ridiculous flip from the outside-turning wing which inverts me towards the ground. Even under full engine power.

 

I've attempted this at airspeeds between 400-670knts. If you attempt to commence a turn at 60 degrees of bank -- forget it.

 

Turning performance doesn't appear to be worse with a full weapon deployment, however it does struggle to reach 500knts at straight and level. Obviously flaps and spoilers retracted.

 

In my opinion, for a war-fighter aircraft, with two massively powerful turbojets, it doesn't fly correctly.

[sea2sky]

Su-25T is an anti-tank upgrade over Su-25A, and it never really went into a full production. And yes - with added electronics/systems it turned out to be a very heavy machine. I highly recommend to get Su-25A if you are interested in that kind of planes.

[cthulhu68]

I'm not sure I would describe the Frogfoots engines as massively powerful. It's capable of Mach .8. Su-27 is capable of Mach 2.35.

[David OC]

The Su-25T feels very accurate to me and is an absolute joy to fly and it's Free!.

 

She ain't no fighter jet Idle_Wild, she's a ground pounder, similar to the A-10, so no "yank and bank" like the fighter jets. Be nice and smooth on the controls.

 

 

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[Idle_Wild]

Any aircraft requires a moderate amount of back-pressure in a turn, in a 60 degree turn, you generally have to pull quite firmly on the stick to keep the nose above the horizon so that you don't lose altitude. My point is, it's not even possible in this craft, regardless of the amount of back pressure, at 30 degrees it attempts to stall, at 60 degrees it tries to flip itself out of the turn. It does not perform correctly.

 

Take these charts as another example of general performance: https://forums.eagle.ru/attachment.php?attachmentid=119337&d=1435854227

https://forums.eagle.ru/attachment.php?attachmentid=119338&d=1435854247

 

There's no way you could rotate in this simulation at 160-180knts. You would be dropping like a lead brick at 250knts.

[Rudel_chw]

It does not perform correctly.

 

 

I beg to difer:

 

 

qjM3LGC0VUQ

[NineLine]

Play nice guys...

[Deezle]

There's no way you could rotate in this simulation at 160-180knts. You would be dropping like a lead brick at 250knts.

It seems like you haven't figured out the Frogfoot is metric :music_whistling:

 

The indicated speed you're seeing is km/h.

[PiedDroit]

The aerobatic performance of this aircraft can't be modelled accurately, surely?

 

I've just downloaded the latest version of DCS 1.5, and have attempted to familiarise myself with the SU-25T, I have never flown fast jets, but it's like flying a lead-brick.

 

With the pylons completely empty, it has no maneuvering ability, if I attempt a medium level turn at 30 degrees of bank, with more than a fraction of back-pressure on the stick, and combined rudder pressure, the stall warning goes off, and I get either a wing-drop on the inside-turning wing or a completely ridiculous flip from the outside-turning wing which inverts me towards the ground. Even under full engine power.

 

I've attempted this at airspeeds between 400-670knts. If you attempt to commence a turn at 60 degrees of bank -- forget it.

 

Turning performance doesn't appear to be worse with a full weapon deployment, however it does struggle to reach 500knts at straight and level. Obviously flaps and spoilers retracted.

 

In my opinion, for a war-fighter aircraft, with two massively powerful turbojets, it doesn't fly correctly.

You should post a short track of your turn, SU-25T is quite nimble when empty.

Empty, you should easily reach 400 knots, which is 730 in the HUD (airspeed displayed is in km/h, not knots).

If you struggle to reach 500 (I assume km/h), I'd check the throttle axis.

Even loaded it goes to 500 without too much a struggle (except with extreme load maybe, however it is much harder to maneuver once loaded).

By any chance are you using an A/B detent? That could be the issue.

You can display the controls (RCtl+Enter if I'm not mistaken), to see if throttle goes to the max.

Edited March 30, 2017 by PiedDroit

[Konovalov]

Flying the Su25T clean is perfectly fine and you can perform some decent turns and aerobatics. There are dozens of videos illustrating it's performance. Even when moderately loaded it handles ok.

[jackmckay]

Su25T airbrakes are not functional.. and that aerobatics movie is speeduped on incams.. its sluggish like old dog..

Edited April 1, 2017 by jackmckay

[VZ_342]

It was a bear for me too, at first. SU-25T definitely requires slow and steady controlling. Remember, you're driving a heavy truck, not a Mazarati or even a Chevy sedan.

 

jackmckay

 

Su25T airbrakes are not functional.. and that aerobatics movie is speeduped on incams.. its sluggish like old dog..

 

Airbrakes ("B", not "W") work for me. I have mine slaved to a convenient button on the throttle and routinely use both to control speed ("one foot on the gas, one foot on the brake...I can't drive 555...")

[Abburo]

 

In my opinion, for a war-fighter aircraft, with two massively powerful turbojets, it doesn't fly correctly.

 

And on what is your opinion based on?

[Mars Exulte]

Su-25 is NOT an 'aerobatic fighter' #1, it's an armored attack aircraft. Aerobatic capabilities are secondary or less on these type of planes. ''Fast jet'' ffs... pretty clear right here what the problem is.

 

More importantly, the T is a bit of a 'Frankenstein' model of the Su-25 that had greatly worsened handling due to the disrupted center of gravity after all the added equipment. They even had to relocate the cannon, further disrupting the handling.

 

Before making a blanket, random complaint, go read about the aircraft. Seriously, even just go to Wikipedia a read a couple paragraphs about this variant.

 

Also, at jackmckay, airbrakes do not automagically slow down multiton aircraft. They are not rotors on a wheel. You don't have any traction. Look at the fins that pop out when you engage the brakes. Now think 'How well would those stop a 30,000lb aircraft?' Answer? NOT VERY.

 

It takes five minutes to research something, but ten seconds to pound out a random complaint.... guess which one people tend to do more often?

Edited April 1, 2017 by zhukov032186

[jackmckay]

zhukov, lets look at airbrake functionality first, it supposed to slow down the airfame by increasing drag coefficient significantly. that's why rugged airbrake system with its powerful heavy duty hydraulic systems is installed at all. Secondary, using airbarkes on Su25T in DCS DOES NOT effectively induce enough drag more than simple high AoA turn would do, so from engineers standpoint this DCSed airbrakes are simple waste of hydraulic power and more increase of overall weight and airframe complexity. It looks like dcs does not simulate fluid at all because this kind of airbrake behavior one would expect only in solid vacuum. At normal landing (-5m/s) approach airbrakes are not effective at all so drag coefficient is not used in speed correction calculations. Even full flaps and airbrakes open does not slow down Frogfoot at ground roll without applying brakes. Just check

forward projection (crosssection) area increment. This just doesn't make sense because Frogfoot is not a train - it flies. Empty weight is around 10t - Mig21 6t but look at drag coefficients of two, one is subsonic high lift attacker other is high mach interceptor and air brake area is kind of similar. Remember that drag is exponential of speed and relative to air density. Frogfoot should decelerate just by reducing throttle. DCS math is wrong on this one.

Edited May 3, 2017 by jackmckay

[Pocket Sized]

Piss poor airbrakes aren't rare in aviation. The F-5, Viggen, and L-39 are as bad or worse in this regard compared to the Su-25. Especially the Viggen, where you have a delta wing to bleed energy and the airbrakes retract automatically above Mach 0.92 or any time the gear is extended.

 

Hell, even the glider I fly suffers from this shortcoming. It's standard procedure to fly the final approach with them fully extended and slip as necessary control your descent rate... and we have the upgraded spoilers that are TWICE as big as the originals! In a regular glider you'd use less than half spoiler and no slip to accomplish the same approach.

[Abburo]

[...] using airbarkes on Su25T in DCS DOES NOT effectively induce [...] .

 

These airbrakes are not supposed to be used to hard stop an airplane. These are supposed to be used for various speed corrections while you are flying in formation, or in diving to not overspeed the airframe, or to correct the landing approach. They are as effective as their size allows to. Generally speaking I am very pleased with SU25T/A behavior and find both planes very pleasant to fly.

 

You cannot expect to brake an airplane from 800km/h to 300 km/h in a matter of seconds. For this type of speed brake you have to consider other maneuvers like scissors, climbing.... etc.

[jackmckay]

As I said before, drag is exponential of speed. That means that airbrake effectiveness is exponentially increased comparing to flight speed. Booth are fighting weight inertial and weight ratios is not exponential as speed vs drag are. Gliders are slow, so slow that you can put you head out and catch raindrops in air. Not case with jets, especially if your landing speed is around 250km/h and approach speed around 350. Non streamlined surface must produce drag, lot of drag and lot of force. That means visible declaration, not just indicative (if so). Not satisfied with airbrake effectiveness at all. I'm speaking of -5m/s final that has very little difference with or without airbrakes. Try that yourself.

Edited May 3, 2017 by jackmckay

[Pocket Sized]

As you just said, drag increases exponenitially relative to speed. What does this mean? At low speed, the spoilers are going to produce a tiny fraction of the drag they do at high speed. Their drag contribution is going to be even smaller when the gear and flaps are extended, which is why they seem so ineffective in landing configuration. In "clean" configuration, the Frogfoot is a VERY slippery airplane, thanks to its thin, lightly swept wings and high mass, which is why it is so reluctant to slow down.

[GGTharos]

The aerobatic performance of this aircraft can't be modelled accurately, surely?

 

 

 

I've attempted this at airspeeds between 400-670knts. If you attempt to commence a turn at 60 degrees of bank -- forget it.

 

Turning performance doesn't appear to be worse with a full weapon deployment, however it does struggle to reach 500knts at straight and level. Obviously flaps and spoilers retracted.

 

.

 

 

Hi :)

 

Let's try to see what's going wrong, because su25t can comfortably pull 7g. Not being able to sustain a 60deg (2g) turn at 300kts is wrong, so let's check a few things off the list:

 

Are you misreading the airspeed as kts instead of kph? The difference is huge ... 150kts is about 300kph.

 

Second, check that your throttle grabs the full range of throttle movement in game. Can you verify that the rpms are correct for full power, and the throttle in your cockpit had moved to the fully forward position?

 

You can verify control axis movement with the axis display using ctrl+enter while in the aircraft as well, and it's one of the best indicators of control response with respect to your physical controls.

 

Finally, posting a SHORT track as suggested would go a long way towards helping :)

[Windsortheater]

The aerobatic performance of this aircraft can't be modelled accurately, surely?

 

I've just downloaded the latest version of DCS 1.5, and have attempted to familiarise myself with the SU-25T, I have never flown fast jets, but it's like flying a lead-brick.

 

With the pylons completely empty, it has no maneuvering ability, if I attempt a medium level turn at 30 degrees of bank, with more than a fraction of back-pressure on the stick, and combined rudder pressure, the stall warning goes off, and I get either a wing-drop on the inside-turning wing or a completely ridiculous flip from the outside-turning wing which inverts me towards the ground. Even under full engine power.

 

I've attempted this at airspeeds between 400-670knts. If you attempt to commence a turn at 60 degrees of bank -- forget it.

 

Turning performance doesn't appear to be worse with a full weapon deployment, however it does struggle to reach 500knts at straight and level. Obviously flaps and spoilers retracted.

 

In my opinion, for a war-fighter aircraft, with two massively powerful turbojets, it doesn't fly correctly.

 

LOL ... try an A-10!

[jackmckay]

ED please check airbrake functionality on Su25T. Everything is fine except airbrakes as they don't work as they should. Could be a bug of some kind.

[The_Nephilim]

The aerobatic performance of this aircraft can't be modelled accurately, surely?

 

I've just downloaded the latest version of DCS 1.5, and have attempted to familiarise myself with the SU-25T, I have never flown fast jets, but it's like flying a lead-brick.

 

With the pylons completely empty, it has no maneuvering ability, if I attempt a medium level turn at 30 degrees of bank, with more than a fraction of back-pressure on the stick, and combined rudder pressure, the stall warning goes off, and I get either a wing-drop on the inside-turning wing or a completely ridiculous flip from the outside-turning wing which inverts me towards the ground. Even under full engine power.

 

I've attempted this at airspeeds between 400-670knts. If you attempt to commence a turn at 60 degrees of bank -- forget it.

 

Turning performance doesn't appear to be worse with a full weapon deployment, however it does struggle to reach 500knts at straight and level. Obviously flaps and spoilers retracted.

 

In my opinion, for a war-fighter aircraft, with two massively powerful turbojets, it doesn't fly correctly.

 

 

 

 

Well I would check your Axis Assignments especailly if you have rudders and a HOTAS..

 

 

DCS has a bad issue with it assigning X & Y Axis to Rudders and throttle even tho it should only be on the stick perhaps this is your problem..

 

 

Altho it is not a Fighter so dont expect fighter performance.. But I imagine your Axis assignments are bonkers as it defaults like that.

 

 

Oh and are you sure it is a stall warning or the other warning which has nothing to do with a stall.. I think it might be aoa indicator or something..

Edited May 4, 2017 by The_Nephilim

[Ironhand]

First, it's been ages since I was last in the Su-25T's pit to do some serious flying. What a delight! She's much better behaved and far more exciting to fly than I remember.

 

That being said, something definitely doesn't seem right on the OP's end. I hope, if he's still around, that he has figured out what it was and is now enjoying this aircraft.

 

Concerning the speed brakes. They seem far more effective than they used to be in the early days. My speed loss now roughly doubles with them extended.

 

Again, this has developed into a very sweet aircraft to fly. Glad I ran across this thread a decided to check things out for myself.

Edited May 4, 2017 by Ironhand

[Pocket Sized]

The other day there was a thread just like this in the A-10C section.

 

We asked about altitudes, control assignments, gross weight, etc... this went on for quite some time, until we all slowly realized that there was no problem and the pilot was just overestimating the aircraft's performance.

 

I am fairly certain that's what's going on here.