Su-25T/Su-25 ground model / physics

[Gecky]

This has probably been discussed already, but I just want to express my frustration in the brittleness of the landing gear of the Su-25 / Su-25T and its inability to move over grass even when empty. My frustration in it is compounded by the fact that the real plane is even designed to have tougher than normal landing gear and was was specifically required the ability to take off/land in ill prepared dirt/grass fields by Russian Air Force as a front line attack aircraft (along w/ the ability to run on diesel).

 

It would have been less frustrating if it were made to be just the same with other DCS aircraft, but as it is now we have to deal w/ the fact that it probably even has the most fragile landing gear in the entire sim. If you fall off the narrow taxiways in a Su-25 (due to lag or for whatever reason), it's almost impossible to get back on without breaking your nose wheel steering and blowing a tire (having to repair or respawn). This is if you can even get back, as it gets stuck in the grass regardless of weight! I just tested this in the grass beside the Gudauta runway: a Su-25T w/ no weapons, 50% fuel wouldn't budge even at full throttle and wiggling the front wheel. The Mig-29 seems even better modeled for it, which defies logic just looking at those tires compared to the extra fat ones on the Su-25.

 

If you do get it at speed over grass, it currently also has one of the worse off-road ability in DCS. In DCS landing a Su-25/T on grass or getting out of pavement at speed is suicide (even in the flattest, most even grass beside a runway)). I'm surprised to find out by accident in an online server yesterday that I am even able to land on the grass beside the runway in the A-10 with minimal damage, despite its evidently flimsier gear (I haven tested what other aircraft could do this). In this video:

a SM3 frogfoot is shown to clearly have this ability, with the bounce in the landing gear even suggesting that this is a much less even surface than the typical grass strips for small aircraft in flying clubs.

 

I think this issue really betrays the character of this aircraft. In the internet, I even spotted this picture: https://preview.redd.it/fjya7i4rkl731.jpg?width=524&format=pjpg&auto=webp&34c0f4c0

which really gives the nickname "frogfoot" justice. If the DCS frogfoot will be more accurately modeled in this aspect I think it would be a perfect balancer for the aircraft which is already handicapped to begin with (having no air radar, no afterburner, and minimal A2A ability). If it could take off and land in at least the flattest grassy areas in the map, and rearm/refuel in FARPS, it would certainly introduce a welcome (and realistic) added dimension especially in online play.

 

BTW I have many aircraft in DCS but find myself often going back to the frogfoot because it is where I started and have much love for what humble airplane it is. I am very thankful that it (and other FC3 planes) have received some attention in the last updates.

Edited August 23, 2020 by Gecky

[LucShep]

Yep, well observed. :thumbup:

 

I haven't used any of the two Su-25 for a long time, but can recall being like this since first DCSW release (1.2 back in early 2013, I think?).

 

PS: having just done a quick test, can confirm - it's still absurdly fragile (unlike real life counterpart). :cry: Please fix this on both SU25s, ED.

[AeriaGloria]

The problem affects all older planes, this is why MiG-29 works so well. With PFM and new 3D model it got the needed attention

[randomTOTEN]

IMO there's been a neglect in this aspect of development because many (new) users just don't want the realism.

This has probably been discussed already, but I just want to express my frustration in the brittleness of the landing gear of the Su-25 / Su-25T and its inability to move over grass even when empty.

My opinion is that the Su-25 family in DCS has some of the best landing gear suspension modeling of any aircraft in any flight simulator, likely to even include FS2020. This causes possibly some grief from users that might not be prepared for it. I know I've blown many tires and gotten stuck many times when I was new on the Su-25. That's part of the fun!

 

My frustration in it is compounded by the fact that the real plane is even designed to have tougher than normal landing gear and was was specifically required the ability to take off/land in ill prepared dirt/grass fields by Russian Air Force as a front line attack aircraft (along w/ the ability to run on diesel)

Key words here being "ill prepared dirt/grass fields" What you consider ill prepared might actually just be "ill maintained" but regardless of this distinction, even you admit that these surfaces have been *to some extent* prepared for aircraft operation. You can't say the same thing about the grass next to the taxiway in Gudata.

 

You can't say the same for the grass next to the runway at Gudata either, or really any runway in the entire world. They were never *prepared* in any way whatsoever for bear the weight of an aircraft, let alone an attack jet!

 

Not all underlying earth is the same, even if it has the same species of grass on top of it.

 

 

It would have been less frustrating if it were made to be just the same with other DCS aircraft, but as it is now we have to deal w/ the fact that it probably even has the most fragile landing gear in the entire sim. If you fall off the narrow taxiways in a Su-25 (due to lag or for whatever reason), it's almost impossible to get back on without breaking your nose wheel steering and blowing a tire (having to repair or respawn).

You should absolutely be punished for this operating mistake. Just as you should be punished with blown tires and collapsed gear by landing too hard, or rolling the tires with excessive groundspeed causing them to burst.

 

Newer aircraft aren't better made, they're worse! Yeah, okay the F/A-18C is designed for CV landings, but currently users can land 1500FPM+ with no damage. They can arrest a wire at 400knots and not rip it off.

Users can slam the F-16 on the pavement with no damage to the gear.

 

The Mig-29 seems even better modeled for it

Likely worse. It should be getting stuck too. The Mig-29 also punishes users for landing nosewheel first. It took pages before the narrative could change from "it's impossible to land" to "it's behaving incorrectly to bad handling." The nosewheel should likely collapse or bounce with less severity when slammed, but users complained that any bouncing was incorrect.

Somebody even posted a video of a hard landing on the mains, and tried to argue that a landing on the nose should behave the same.

 

They then tried comparing it to the Su-27, where you can land on the nosewheel with no punishment. That's not an improvement, that's regression in physics. You should absolutely be punished with a hard bounce or gear collapse with such negligent handling of the Flanker!

 

Just like you've posted a video of a jet on an airstrip, and assert this should apply to any random stretch of grassy field on earth. It doesn't... not automatically.

 

If you do get it at speed over grass, it currently also has one of the worse off-road ability in DCS.

Notice how few off-road tricycles exist? It's not a good design for an off road vehicle. But it's a good design for jet fighters. Surprise that jet fighters can't go fast off-surface...even when equipped with big tires. But if you go too slow on earth that hasn't been prepared to bear aircraft loads you dig in and get stuck. It's a fine line you walk, and you can't guarantee that you win.

That's why surfaces are prepared for this type of thing.

 

I'm surprised to find out by accident in an online server yesterday that I am even able to land on the grass beside the runway in the A-10 with minimal damage, despite its evidently flimsier gear (I haven tested what other aircraft could do this).

I just made 4 attempts at this next to Senaki with no success... I would very much like to see somebody post a track of a successful landing off-surface (gear down). The sim does a functional job of gear up landings at least.

 

If the DCS frogfoot will be more accurately modeled in this aspect I think it would be a perfect balancer for the aircraft which is already handicapped to begin with (having no air radar, no afterburner, and minimal A2A ability). If it could take off and land in at least the flattest grassy areas in the map, and rearm/refuel in FARPS, it would certainly introduce a welcome (and realistic) added dimension especially in online play.

Why should any of this matter? This is a simulator, not a competitive game. The point isn't to 'buff' an aircraft for online balance. The real aircraft can do certain things, and it cannot do certain things.

 

Lets talk about what it can and cannot do, not what gets you a higher points on the scoreboard. As of yet, I don't think your claim of "more accurate" is valid.

[draconus]

There's this misconception that you should be able to land at the airfield whatever the conditions with just enough skill but it's not true. Just as IRL you should divert to a safer airport instead. That's why it's called "Hard landing training" for Su-25T - night, strong crosswind, rain, thunderstorm, short runway, you can't use parachute or it'll drag you off the runway and you'll burst the tires and break the nosewheel easily with not careful rudder input.

Otoh you can currently land most aircraft on the grass field or desert but it's risky.

[Mars Exulte]

A prepared landing strip (ie compacted dirt runway) or a highway is not the same thing as ''a field''. ''Rugged undercarriage'' and ''rough landing/takeoff capability'' is not the same thing as ''off road ATV''. It is an airplane, not a 4x4 Jeep.

 

DCS has different ground conditions, btw. One field can be soft, another less so, depending on conditions. As for running off taxiways... The ground AROUND an airfield is not prepared for aircraft to drive around on. Why would it be? There are taxiways and a runway RIGHT THERE. You know what they call a pilot that runs off the taxiway in Russia? Same thing they do in every other country, ''idiot''.

 

The taxiways are there for a reason. Use them.

 

As for the Frogfoot having inferior ground handling while you're ''offroading'' @@ It WOULD have inferior handling with that tall, narrow wheelbase.

 

They're probably also correct about the fms. The Su-25s are the last of the older style of fms, and probably are a little wonkg under certain conditions in comparison to others. All the same, keep it on the oavement and you won't have that issue.

[Maxthrust]

I feel if anything needs to be adjusted it is the effectiveness of the drag chute (acting like a ship anchor) and addition of proportional & independent main wheel brakes.

 

I wonder how would a real A-10 ride on Russian concrete pavement blocks that was cast 40 years ago lol. Su-25 landing gear can take a lot of punishment imo.

[draconus]

I feel if anything needs to be adjusted it is the effectiveness of the drag chute (acting like a ship anchor) and addition of proportional & independent main wheel brakes.

What's wrong with the chute now? What is proportional wheelbrakes? And afaik no differential braking is available in the Su-25.

[randomTOTEN]

It seems to me the chutes don't "open," in that as soon as the chutes finishes their deployment animation the drag suddenly increases to that of the inflated chute. It's very jarring, and I would expect at least some sort of more gradual drag increase as the chute is inflating. Basically the drag should increase somewhat proportionally to the inflated chute area during the deployment process. Right now it feels very 0 then 1.

 

It believe the brake system is similar to other Russian aircraft we have in DCS (and similar to the Spitfire system). A stick mounted single brake lever controls pressure to both main wheel brakes, with the rudder proportioning the force with pedal deflection.

 

I think the brakes are fine.

Edited August 26, 2020 by randomTOTEN

[Volator]

What's wrong with the chute now?

 

This:

 

I feel if anything needs to be adjusted it is the effectiveness of the drag chute (acting like a ship anchor.)

[draconus]

Right now it feels very 0 then 1.

Because chute deployment is quite fast (miliseconds). Of course it's model is simplified but it wouldn't change anything much if implemented fully.

[randomTOTEN]

I guess that's true, and a good point. Just looked up some footage and took probably less than a second to fully inflate. I also have to consider that the drag from the chute has to be transferred to the aircraft through the chute lines.

looking at a deployment, the drogue pulls the chute out (so it's not actually pulling against the aircraft yet), and the main chute lines probably come under tension as the chute is finishing inflating, so it probably is that sudden of an onset.

[Gecky]

Ok, sorry for using "off-road" unable to think of a better word better word, "off pavement" handling is more of what I meant. Also the Su-25 manual says it was designed for "unimproved" strips rather than "unprepared". So maybe I got a bit enthusiastic there in what I wanted to ask for, but still in the state it is in now it is relatively more fragile than other aircraft, which can't be accurate for what this plane is supposed to be. Definitely the gear modeled now is incapable of the takeoff in the video and picture I supplied in the first post

[randomTOTEN]

which can't be accurate for what this plane is supposed to be.

Yes, it certainly can. Especially since many of those other aircraft are still in active development.

Definitely the gear modeled now is incapable of the takeoff in the video and picture I supplied in the first post

This isn't true either. Are there any grass airfields on any map in DCS? Can somebody try taking off and landing the Su-25 from it?

[draconus]

Are there any grass airfields on any map in DCS? Can somebody try taking off and landing the Su-25 from it?

Here you are taking off from full grass Gudauta field. Any questions?

Su-25T grass TO.trk

[randomTOTEN]

Nice track! I was doing tests with the A-10C, but not the Su-25.

 

Any questions?

Yes I do have one. How do I better explain the difference between a grass runway, and the grass next to a runway?

 

 

It took me a couple tries with the landing, but I was successful in both takeoff and a landing from the grass at Gudauta in your track. Surprising, I really have never tried that much before.

 

Lol, even using your own track I eventually got myself stuck in the dirt! 100% throttle, trying to rock the plane with gunning the engines, rocking the nosewheel, cycling the controls. Couldn't do it. Got myself good and stuck. Somebody call the airfield management.. get me a tractor or mower and a chain.:thumbup:

[Gecky]

2 tracks, both landing in the same flat field in Crimea, both aircraft no weapons, 40% fuel. no use of brakes. The A10 didnt even damage steering BTW.

A10 field landing.trk

Su25 field landing.trk

[randomTOTEN]

The A-10A exploded shorty after nose wheel touchdown both times I watched your track.

[draconus]

2 tracks, both landing in the same flat field in Crimea, both aircraft no weapons, 40% fuel. no use of brakes. The A10 didnt even damage steering BTW.

Watched your tracks - both crash on landing. Don't use the area that is not modeled.

I uploaded my tracks - both successful at Gudauta. But it's still risky and the grass is not prepared for landing.

Su-25T grass landing.trk

A-10A grass landing.trk

[Ironhand]

Gecky said:

2 tracks, both landing in the same flat field in Crimea, both aircraft no weapons, 40% fuel. no use of brakes. The A10 didnt even damage steering BTW.

I'm late to the topic as seems usual these days. I viewed both tracks in the current Beta as well as the current Release. The Su-25T crashed as soon as the nosewheel touched. The A-10 landed successfully in the Release version of the sim.

 

I just want to add my two cents. As others have noted, success depends on where you attempt to land--and I still haven't figured out how to tell ahead of time whether the field will support a landing or not--as well as the aircraft you use. As you've discovered, the Su-25 and Su-25T seem to have the most difficult time. That nosewheel causes all sorts of problems when it touches down at speed. The longer you can keep weight off of it, the better off you are.

 

For whatever reason, the FC3 aircraft that's most successful at all of this is the Su-27/-33. Both will land places that the others have a difficult time with. (I have deadsticked into more fields than I want to count.) As you've discovered, the A-10 seems to be the next best at this. There are some areas of the map, though, where nothing will land successfully.

 

Here's a short video showing the behavior of 4 different aircraft on the same grassy area. Of the 4 aircraft, the Su-25T was the only one to lose its ability to steer. There's nothing special about this place. I just opened the Caucasus map, closed my eyes, scrolled and used the area the mouse pointer ended on.

 

[video missing]

 

The track files used to create the video are attached. Made with the current Beta.

 

(The A-10 track will start with a sharp turn away. When I jumped into the cockpit, I realized that I had gotten so used to metric, that I had no idea what the A-10's stall speed, etc would look like. The circle away was my attempt to re-educate myself.)

Su-27_Grass Landing.trk

A-10 Grass Landing.trk

MiG-29s Grass Landing.trk

Su-25T Grass Landing.trk

Edited December 4, 2020 by Ironhand