SU-25T Nose Wheel

[RazorTM]

When landing the SU-25T, if I need to steer the airplane back toward the centerline, the tire is almost always ripped off the wheel, making stopping and taxiing nearly impossible.

 

Here's a video:

 

You can see that I started turning toward the centerline, and when I get close to the centerline, I start steering back straight so that I merge with the centerline, but the nose wheel twists way too much and rips the tire off. I'm using very gentle inputs (as gentle as I can with my crappy Logitech Extreme 3D Pro) that aren't any more harsh on this airplane than any airplane I've flown in real life, so I believe that the front tire's strength needs to be adjusted a little bit.

 

The track file for the video above is also attached.

wheelbust02.trk

Edited January 9, 2015 by RazorTM

[JNASova]

I am not shure how the things are modeled at DCS World,but your plane was pretty heavy.You had almost full internal tank,almost full pack of vihor missiles,2 x empty external tank,and 2 x A-A missiles.You was good for take off and to start the mission,not for landing.

Second thing,as far as I can see,maby you do sharp turn,as you tried suddenly taken a turn, like you are using rudder from keyboard.Presing button on the keyboard might add 100% rudder input.With so much weight,not good thing.

I repeat,I dont know how that things are modeled.In real life it would be a problem.

Thry to do it with empty plane,fuel 500,no sharp turns and see what is going to happend.

Edited January 9, 2015 by =JNA=Sova
Forgot to add something.

[RazorTM]

I am not shure how the things are modeled at DCS World,but your plane was pretty heavy.You had almost full internal tank,almost full pack of vihor missiles,2 x empty external tank,and 2 x A-A missiles.You was good for take off and to start the mission,not for landing.

Second thing,as far as I can see,maby you do sharp turn,as you tried suddenly taken a turn, like you are using rudder from keyboard.Presing button on the keyboard might add 100% rudder input.With so much weight,not good thing.

I repeat,I dont know how that things are modeled.In real life it would be a problem.

Thry to do it with empty plane,fuel 500,no sharp turns and see what is going to happend.

 

Actually, the Vikhr tubes were empty (looks like a graphics glitch from doing a replay, since I had used all of my external stores flying the mission), I had no more AA missiles on board, and I of course used the two heavy missiles (K-29T and Kh-58U), so the plane wasn't very heavy on landing. This is a typical scenario for RTB and I bust the nose wheel every time. Landing in no wind with no weapons loaded and minimum fuel just isn't realistic for the campaign missions, so why should I do any testing in that configuration???

 

I think in real life that with the way I'm doing it, the plane would much sooner tip over in the turn than the tire be ripped off the rim. There seems to be no resistance to turning the nose wheel when it's firmly planted on the ground, so you can unrealistically jerk the wheel to the left or the right in this game. I think this is the root of the problem. The strength of the tire might be correct after all?

Edited January 9, 2015 by RazorTM

[RazorTM]

Here's one more video that shows in detail that you can turn the nose wheel freely in either direction even though it is in firm contact with the ground. This is completely unrealistic and the root cause of the problem.

 

[Witchking]

nice landings. I don't know if there is an option to disable/enablw nose wheel steering. But...if it is available IRL, I think adding that would definitely help with that issue.

[xaoslaad]

I can't tell, but are you riding the break the entire time? Try using it for short bursts instead if so. Rely on the chute to slow you most of the way down. They are nice landings otherwise though. I think basically what you're seeing is applying the brakes way too much at high speed and basically causing this: https://www.youtube.com/watch?v=vhi3DfEB_yc

Edited January 9, 2015 by xaoslaad

[RazorTM]

Nope, both of these incidents occurred BEFORE using the wheel brakes. The first one was while trying to get back near the center of the runway so that I wouldn't run off the edge. I started braking after moving to the centerline.

 

On the second one, the drag chute pulled me to the right and I was steering to the left to counteract it when the tire was ripped off. I usually pop the chute, slow down to ~100km/h, then drop the chute and start using the wheel brakes.

[Dr_Arrow]

RL landing weights for Su-25 are defined as follows:

Maximal available landing weight = 13 300 kg

Maximal landing weight = 12200 kg

Recommended landing weight = 10800 - 12200 kg

 

For Su-25, the landing weight from 12200 kg -> 13 300 can form only 3% of all landings and landings at such weights should be done only in case of emergencies.

 

These numbers could be a bit higher for the T version, I always land with fuel less than 1500 kg without weapons and with fuel at 600 kg if I have some weapons left.

[boquinauer]

Hi RazorTM.

 

This issue is very common in the Su25T. Specially during landings with a crosswind component of more than 4 mps. The reason basically is that you can't block the nosewheel steering like in other Russian airplanes. Maybe because this is not a "hardcore" advance system modeled aircraft. :smilewink:

[esb77]

Don't use large or sudden rudder inputs above about 100 km/h if the nosewheel is on the ground.

 

Don't slam the nose of the plane down when landing.

 

Don't use full continuous wheelbrakes above 150 to 200 km/h (depending on plane weight).

 

 

It really helps to have both rudder and wheelbrakes bound to an axis on your control setup. It makes using a light touch when landing the Su-25 much easier. You can try changing the curvature on your yaw axis for your controller, or if that fails, light quick taps on the keyboard rudder controls. For the turn induced blowouts it's a matter of rate, below a certain threshold you can swerve around as much as you like, above the critical threshold it'll rip the tire off of the rim almost instantly.

 

 

With practice, you can plunk that sucker down pretty hard without popping the nosewheel.

 

Heavy loading on the nose and forces from the side are what tend to destroy the nosewheeel tire, but once you get down to about 100 km/h the nosewheel becomes a lot more tolerant of abuse.

 

At one point I wrote a beginner's guide for the Su-25T in DCS, and there was a whole section on how to taxi with a blown nosewheel.

 

Once you get used to it, it's not really a problem, and the wheel will survive fairly terrible landings. It just won't survive the specific conditions it hates.

 

 

I haven't reviewed in the past 6 months or so, but historically in DCS there has not been a control for nosewheel steering for the Su-25T, it's just tied to the rudder inputs. Having a nosewheel steering on/off implemented would make avoiding the blown tires a lot easier.

Edited February 4, 2015 by esb77

[Shaman]

Does not happen here, I believe you must keep practicing.

Also, getting rid of weapons does not mean you are at safe landing weight. Bring up payload screen to check your current weight, amount of fuel left in tanks is important. Stay in pattern and burn all unnecessary fuel practicing go-arounds (not touch&gos!) at own decision height. It is very good training to get your approaches spot-on and burn that extra fuel to be safe to land.

 

1. make sure controls are set correctly, curves for yaw and all; watch/read about cross-wind approach and final flare techniques - tons of material on internet;

2. straighten the plane before touchdown on main landing gear; you can't traverse left or right at touch down;

3. at touch down work rudder to keep plane straight;

3. once straight running down the runway, continue to keep nose wheel up (do not pitch too high) as long as possible using airplane's fuselage at positive pitch as air-break to reduce speed until moment you can't hold nose wheel up and make it touch down softly.

 

Oh, never ever release any bit of pressure pulling on stick after flare, you can only add to stick pressure.

Edited February 20, 2015 by Shaman