Jump to content

[NOBUG] Landing Problems


LeCuvier

Recommended Posts

I used to find landing the Viggen quite easy and fun with AFT and thrust reversal. Now I haven't used the Viggen for some time and now find it almost impossible to land without crashing. Two problems:

1. Cannot reduce speed. It seems that the viggen has no drag, even with speed brake engaged and gear down. I approach at about 400 km/h at 500m altitude. Cut the throttle, lower gear, speed brake out and glide down to the runway with AFK and reversal ON. The speed does not reduce, although I have an Alpha of about 12°. It even increases to almost 500 km/h. So if I try to touch down I smash the landing gear.

2. If I somehow manage (don't know why) manage to touch down at about 300 km/h and the thrust reversal activates, the aircraft veers to the right especially if I use brakes even though gently, and it tends to flip over. In fact, even using the brake during taxying causes a sharp veer to the right.

 

I tried this several times and I do not see what I'm doing wrong. Looks like two bugs to me. Same in OB and stable version.

LeCuvier

Windows 10 Pro 64Bit | i7-4790 CPU |16 GB RAM|SSD System Disk|SSD Gaming Disk| MSI GTX-1080 Gaming 8 GB| Acer XB270HU | TM Warthog HOTAS | VKB Gladiator Pro | MongoosT-50 | MFG Crosswind Pedals | TrackIR 5

Link to comment
Share on other sites

I used to find landing the Viggen quite easy and fun with AFT and thrust reversal. Now I haven't used the Viggen for some time and now find it almost impossible to land without crashing. Two problems:

1. Cannot reduce speed. It seems that the viggen has no drag, even with speed brake engaged and gear down. I approach at about 400 km/h at 500m altitude. Cut the throttle, lower gear, speed brake out and glide down to the runway with AFK and reversal ON. The speed does not reduce, although I have an Alpha of about 12°. It even increases to almost 500 km/h. So if I try to touch down I smash the landing gear.

2. If I somehow manage (don't know why) manage to touch down at about 300 km/h and the thrust reversal activates, the aircraft veers to the right especially if I use brakes even though gently, and it tends to flip over. In fact, even using the brake during taxying causes a sharp veer to the right.

 

I tried this several times and I do not see what I'm doing wrong. Looks like two bugs to me. Same in OB and stable version.

 

 

Can you make a short video of the approach and landing phases?

Visit https://www.viggen.training
...Viggen... what more can you ask for?

my computer:
AMD Ryzen 5600G | NVIDIA GTX 1080 Ti OC 11GB | 32 GB 3200 MHz DDR4 DUAL | SSD 980 256 GB SYS + SSD 2TB DCS | TM Warthog Stick + Throttle + TPR | Rift CV1

 

Link to comment
Share on other sites

Actually I found that I was trying to land with auto-pilot in ATT mode. I corrected that error, plus I made sure I only engaged the AFK when my speed was near 300 km/h and alpha above 10°. The landing then became manageable, although I still find that the drag is extremely low compared with other jet fighters like F-5E or even F/A-18. I cannot prove it but it appears unrealistic.

The wheelbrake is still a problem if I use the "W" command in order to avoid asymmetric braking via the two wheelbrake axes. The aircraft veers sharply to the right and that's dangerous. I also tried the single-axis wheelbrake and that also makes me veer to the right and is therefore as dangerous as the "W" command.

So I used max power on the thrust reversal with very cautious use of the 2-axis wheelbrake command to shorten the landing run.

The problem with the brake has been confirmed by other users and is almost certainly a bug.

LeCuvier

Windows 10 Pro 64Bit | i7-4790 CPU |16 GB RAM|SSD System Disk|SSD Gaming Disk| MSI GTX-1080 Gaming 8 GB| Acer XB270HU | TM Warthog HOTAS | VKB Gladiator Pro | MongoosT-50 | MFG Crosswind Pedals | TrackIR 5

Link to comment
Share on other sites

... The wheelbrake is still a problem if I use the "W" command in order to avoid asymmetric braking via the two wheelbrake axes. The aircraft veers sharply to the right and that's dangerous. I also tried the single-axis wheelbrake and that also makes me veer to the right and is therefore as dangerous as the "W" command. So I used max power on the thrust reversal with very cautious use of the 2-axis wheelbrake command to shorten the landing run. The problem with the brake has been confirmed by other users and is almost certainly a bug.

 

 

During the landing roll, I prefer to depress W for lets say 1 second, then release for a few tens of a second, then depress it again, while the reverser in action. Good enough for most situations. If I had to land on a street, I would use reverser with full engine power, and the brakes half second ON half second OFF. This is because I only have keyboard for braking ... no pedals here :(

Visit https://www.viggen.training
...Viggen... what more can you ask for?

my computer:
AMD Ryzen 5600G | NVIDIA GTX 1080 Ti OC 11GB | 32 GB 3200 MHz DDR4 DUAL | SSD 980 256 GB SYS + SSD 2TB DCS | TM Warthog Stick + Throttle + TPR | Rift CV1

 

Link to comment
Share on other sites

Actually I found that I was trying to land with auto-pilot in ATT mode. I corrected that error, plus I made sure I only engaged the AFK when my speed was near 300 km/h and alpha above 10°. The landing then became manageable, although I still find that the drag is extremely low compared with other jet fighters like F-5E or even F/A-18. I cannot prove it but it appears unrealistic.

The wheelbrake is still a problem if I use the "W" command in order to avoid asymmetric braking via the two wheelbrake axes. The aircraft veers sharply to the right and that's dangerous. I also tried the single-axis wheelbrake and that also makes me veer to the right and is therefore as dangerous as the "W" command.

So I used max power on the thrust reversal with very cautious use of the 2-axis wheelbrake command to shorten the landing run.

The problem with the brake has been confirmed by other users and is almost certainly a bug.

The airbreak on the viggen were terrible even irl. Sorry the enclosed picture is from a swedish viggen pilot. Which says that they were allowed to lower the gear in 600 kmh

3B15DAFE-47A3-4890-AF61-298B27868416.jpeg.f4bf459e8410ed0ac1fc6612985103ee.jpeg

MY SYSTEM SPECS: Hardware Intel pentium 3 @ 800 MHz, 256 Mb RAM, Geforce 2 64Mb, Dell screen 1024x768 + Microsoft sidewhiner joystick + TrackIR 2 + TrackClitPro SOFTWARE: Microsoft Windows 98, Noice Attack & VIASAT PRO, SnackView

Link to comment
Share on other sites

Try not using the AFK, I suspect you have it set too high. No use having an automatic speed control set to 500 if you're trying to go slower than that.

 

 

:megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol::megalol:

Night Ops in the Harrier

IYAOYAS


 
Link to comment
Share on other sites

About the asymmetric braking part, make sure you pull the stick back when you brake hard. The nosewheel loses a lof of effectiveness when all the pressure is put on it during hard braking. I think it is even part of SOP when doing thrust reverser landings.


Edited by Marsvinet
Link to comment
Share on other sites

I just take my time with the Viggen landing, and its no problem then.

I prefer to land with TILS, so when Im around 10km from the approach circle (cant remember its name), I engage AFK, and 500m alt (barometric) with QFE for airfield. Autopilot is on, and when I reach the turn for final, I do that with autopilot and just hit trim in the direction, which puts me in a nice 30 degree bank.

When Im 6km from the airfield (waypoint range), I lower the landing gear, disengage autopilot and just follow the HUD indications. Glide in, always on the money, 270-280km/h on touch down, with a 12 degree AOA.

 

If I dont use TILS and just come in with visual landing, then I can come in quite hot, I just bleed a lot of speed in my initial turn - sharp one, high G to get rid of that speed, aiming for 500-550km/h. And I always use AFK (and trust reverse). As soon as your gear is down, its controlling your speed for a 12 degree AOA landing. Just be patient. 5km is quite close to the runway.

 

Ive never messed up a landing in the Viggen. By far the easiest plane to land, along with the A-10C. Just trust the AFK, its doing a great job ;).

 

Edit: The only times I use toe brakes is when I had a real bad approach and went long, or when putting it down on a roadbase, and even then, I dont touch the brakes until Im off trust reverser, and then its just gentle (I use a Y saturation of 50, plus a 30 curve on the toe brakes).


Edited by Knock-Knock

- Jack of many DCS modules, master of none.

- Personal wishlist: F-15A, F-4S Phantom II, JAS 39A Gripen, SAAB 35 Draken, F-104 Starfighter, Panavia Tornado IDS.

 

| Windows 11 | i5-12400 | 64Gb DDR4 | RTX 3080 | 2x M.2 | 27" 1440p | Rift CV1 | Thrustmaster Warthog HOTAS | MFG Crosswind pedals |

Link to comment
Share on other sites

  • 9 months later...

I'm having big problems landing using TILS. I can land the Viggen in NAV mode by eye just fine - in fact it's one of the easier DCS planes to land. But the moment I go into TILS and LANDNING mode it's fighting me in pitch, roll and yaw. What's up? Is the plane trying to land itself and I'm just getting in the way? I've got the SPAK level of damping autopilot on but none of the other levels. Is there a mode where I can just have the glidepath guides up for low vis but fly the plane myself? I'm thoroughly confused and the manual isn't helping.

Link to comment
Share on other sites

I'm having big problems landing using TILS. I can land the Viggen in NAV mode by eye just fine - in fact it's one of the easier DCS planes to land. But the moment I go into TILS and LANDNING mode it's fighting me in pitch, roll and yaw. What's up? Is the plane trying to land itself and I'm just getting in the way? I've got the SPAK level of damping autopilot on but none of the other levels. Is there a mode where I can just have the glidepath guides up for low vis but fly the plane myself? I'm thoroughly confused and the manual isn't helping.

 

I have to test this.

Can you provide a video sequence of these happenings?

Visit https://www.viggen.training
...Viggen... what more can you ask for?

my computer:
AMD Ryzen 5600G | NVIDIA GTX 1080 Ti OC 11GB | 32 GB 3200 MHz DDR4 DUAL | SSD 980 256 GB SYS + SSD 2TB DCS | TM Warthog Stick + Throttle + TPR | Rift CV1

 

Link to comment
Share on other sites

Try not using the AFK, I suspect you have it set too high. No use having an automatic speed control set to 500 if you're trying to go slower than that.

 

AFK reduces power to maintain 12deg alpha when gear is down. It only maintains 500 when gear is up. OP states that AFK was activated when gear was down.

 

That being said I find the Viggen bleeds airspeed rapidly when gear down. The training has you do it when speed is below 550

Link to comment
Share on other sites

I'll try to get some video. Practice seems to be reducing it but I can't work out what I'm doing less of. I noted that, in phase 3 of the approach, in descent, I switched off the Alt autopilot and got a massive and immediate swerve down and to the side. I think I'll nix the alt autopilot far earlier.

Link to comment
Share on other sites

All good points, Last Rifle and Mike, but I wasn't using AFK at the time. I've started doing so and it helps greatly.

 

 

 

Overalll it's a magnificent plane. I've had it for a year and done nothing with it and am just discovering it.


Edited by MrShooty
Link to comment
Share on other sites

I used to find landing the Viggen quite easy and fun with AFT and thrust reversal. Now I haven't used the Viggen for some time and now find it almost impossible to land without crashing. Two problems:

1. Cannot reduce speed. It seems that the viggen has no drag, even with speed brake engaged and gear down. I approach at about 400 km/h at 500m altitude. Cut the throttle, lower gear, speed brake out and glide down to the runway with AFK and reversal ON. The speed does not reduce, although I have an Alpha of about 12°. It even increases to almost 500 km/h. So if I try to touch down I smash the landing gear.

2. If I somehow manage (don't know why) manage to touch down at about 300 km/h and the thrust reversal activates, the aircraft veers to the right especially if I use brakes even though gently, and it tends to flip over. In fact, even using the brake during taxying causes a sharp veer to the right.

 

I tried this several times and I do not see what I'm doing wrong. Looks like two bugs to me. Same in OB and stable version.

 

 

 

 

 

 

Did you get the veering off the runway thing sussed, LeCuvier? The first few times I landed the Viggen it was sweet and controllable. Now it inevitably veers and flips even when I land straight at 200kmph and use the thrust reverser. I've not got an assymetric load out so I can't figure out why it pulls over so immediately.

Link to comment
Share on other sites

Now it inevitably veers and flips even when I land straight at 200kmph and use the thrust reverser. I've not got an assymetric load out so I can't figure out why it pulls over so immediately.

 

Hm... for me this sounds like an axis mixup of your input device.

While applying brakes, it might add rudder or something ... ????

 

Remember:

Touchdown slower than 320 km/h (due to Vmax tyre).

Touchdown at an AOA of not more than 12° for normal daily ops.

Touchdown at a vertical speed not exceeding 2.96m/s.

Gently use the reverser (hm... lets say half).

Super gently use the brakes (I am on keyboard, cannot give any hint if you are using pedals).

Use full nose wheel steering at speeds not exceeding 20 km/h (yes, it means you have to taxi slower than most beginners think ...)

While using the reverser, you may(!) slightly pull on the stick to re-increase force on the main landing gear for better braking action using the wheel brakes (the reverser will lift the aircraft slightly ... happend to a former Viggen pilot I personally know, the wheels lost contact to ground .. no joke!).

I personally NEVER use AFK, it makes landings during bumpy and windy air more difficult (just my personal opinion).

 

 

This is from the manual, and it works (pay special attention to the bold sections):

10. Aim for a 3° angle of descent and reduce airspeed to correspond to 12° α (AoA). The line in the HUD during LANDN P/O corresponds to 2.86°.

11. Place the descent line on the runway threshold and centre the sight dot on the centreline, steer the flight path indicator onto the line. Maintain attitude. Strive for a touchdown at about 100-200 metres in on the runway.

12. At 15 metres altitude above the runway (30 if not using the radar altimeter), the HUD will change to the descent rate mode. The previous 2.86° line represents the maximum vertical velocity (2.96 m/s).

Hope you find your way through the jungle ...:smilewink:

 

Edit:

 

I did some fun landings today, and I made 3 videos showing a few things NOT according to book.

 

Normal landing, not according to book, but nice & smooth, needs work on the stick & throttle:

 

Special landing procedure, also not according to book, using ATT engaged, needs only work on the throttle:

https://www.youtube.com/watch?v=NYoYu6f2-So

 

Special landing procedure, also not according to book, using ATT and AFK 12° engaged, needs only monitoring work (works somewhere around 17:00 UTC time due to long upload):


Edited by TOViper
3 videos added

Visit https://www.viggen.training
...Viggen... what more can you ask for?

my computer:
AMD Ryzen 5600G | NVIDIA GTX 1080 Ti OC 11GB | 32 GB 3200 MHz DDR4 DUAL | SSD 980 256 GB SYS + SSD 2TB DCS | TM Warthog Stick + Throttle + TPR | Rift CV1

 

Link to comment
Share on other sites

Thanks TOViper and everyone for your help. It made me go back through my landing procedure and I think I've solved it.

 

 

The issue with the "fighting the autopilot" on the approach was all in my head. I was following the steering cues to LB and LF too literally so when they jumped or switched as they do during the circuit I was actually getting a bizarre kind of pilot induced oscillation. I needed to back off and realize that it is me flying the plane and the HUD is giving clues, not instructions.

 

 

The swerving on the runway is the thrust reverser. I was treating it like the parachute on the Mirage: Pull the lever and jack it to the max whatever. But it's not like forward thrust - nice and linear - it pulls you all over if you run it too high.

 

 

Finally the autothrottle needs a bit of watching too. It does a great job but it brings you to the threshold in a very gentle fashion without any additional speed for corrections. So you need to ensure that you are well lined up good and early since, if you need to do a last minute yaw or roll to get straight, you'll be out of energy with no throttle response and you'll drop like a stone. So get fully lined up when you still have enough height. That's just good flying anyway.

 

 

So now I seem to be able to do a decent TILS approach and landing using all the fancy systems. On to the next frustration - whatever that will turn out to be.:pilotfly:

Link to comment
Share on other sites

So now I seem to be able to do a decent TILS approach and landing using all the fancy systems. On to the next frustration - whatever that will turn out to be.:pilotfly:

You shouldn'T be frustrated. It is a challange, nothing more :P

Sometimes in the near future you will be able to handle all this stuff, and then you maybe think "man, there are just a few things to realize, ... and If I would have known this and payed attention to this and that ... man its so easy..."

 

 

In fact all this is easy, once you are able to perform it.

But before ... its a hard life :)

 

Flying is easy.

Landing ... yeah, its just a controlled stall 10cm above the runway.

Visit https://www.viggen.training
...Viggen... what more can you ask for?

my computer:
AMD Ryzen 5600G | NVIDIA GTX 1080 Ti OC 11GB | 32 GB 3200 MHz DDR4 DUAL | SSD 980 256 GB SYS + SSD 2TB DCS | TM Warthog Stick + Throttle + TPR | Rift CV1

 

Link to comment
Share on other sites

I find with thrust reverser on high some nose down on the stick helps greatly from veering.The reverser pushed the nose into the ground, but I think the modeled effect isn't enough if you have a lot of nose high trim added in. Typically when you're landing there's a decent amount of nose up trim you end up doing. When wheels on ground it can have an odd effect with he thrust reverser kicked on high.

Link to comment
Share on other sites

  • 2 months later...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...