Gear and landing with the braking parachute.

[simapajik]

Greetings to all fans LN MiG-21bis.

 

Can you please pay attention to the video link.

 

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The video is a demonstration flight of MiG-21 Czech Air Force. MiG-21 pilots released braking parachute just before touchdown the aircraft. It's hard to maneuver. MiG-21 chassis is designed to withstand severe conditions for landing. LN MiG-21bis is in my opinion very sensitive gear on landing. If a landing is fine, gear breaking down. Are you of the same opinion. ?

 

The question for developers of Leatherneck. Is the ability to adjust the gear to withstand larger impact with the runway. The possibility of releasing a parachute over the runway, so the landing gear before landing damaging? Please.

 

I tried to maneuver by video. The landing speed of 300 km / h, the slope of 3 degrees. About one meter above the runway, I released the brake parachute and pulled the lever to control me. Gear damaged.

[Vincent90]

You'll see him descending pretty fast before going 0 m/s and pulling the brake chute to enter the final stage of landing. Not my way of landing, but nothing wrong with it.

 

My DCS rig is broken for a couple of months now so can't test the current MiG-21 build, but IIRC the MiG-21 landing gear sensitivity is not so bad as long as you keep your vertical altitude at a 2 m/s descend, what this pilot manages to do.

 

By the way, 300 km/h is WAAAAAAAY to slow to land the plane, try to land at 360 km/h and the landing will be a lot smoother.

 

Have fun! ;)

Edited August 13, 2016 by Vincent90

[Frederf]

MiG-21 is quite sensitive to landing weight. 300 km/h is not slow at all. With ~500L and clean touchdown is in the 260-280 km/hr range no problem. The 330 km/h final approach recommendation is because there is no failure warning for BLC which is safety critical. In the case of emergency landing after takeoff, jettison all stores and touchdown with full fuel is 290-300 km/h. There is no excuse to touchdown above 300 km/h even with flaps in the takeoff position. Only with no flaps is the touchdown speed above 300 km/h.

 

Deploying the chute has a terrific nose down moment which shouldn't be there. I deploy with 400L left at 260 km/h at 1m height and main gear are absolutely fine. However nose gear is demolished. It is not possible to prevent this nose-down motion with control stick and it is smashed.

 

If you are damaging main landing gear then you are landing too fast, heavy, or deploying the chute with too much height. Try again being less than 6800kg, ~260 km/h, and a height of not more than 1m before deploying chute.

 

The big difference in the video to DCS is the fact that the airplane is not violently pitched down by the chute and the nose wheel can even be off the ground after main touchdown. It's as if the DCS chute is modeled as a rigid object extending directly aft instead of by airflow. The nose down torque is insane.

 

I managed to not break any landing gear deploying at ~1m height the chute by being faster and steeper than normal and having a positive pitch rate at the time of chute deployment. It would be very difficult to do reliably.

[Vincent90]

Do you even have the aircraft Frederf?

[grunf]

By the way, 300 km/h is WAAAAAAAY to slow to land the plane, try to land at 360 km/h and the landing will be a lot smoother.

300 km/h is a good landing speed, unless you're way too heavy.

[simapajik]

Manual writing - landing speed of 280 km / h at touchdown. Braking parachute was torn off at a speed higher than 350 km / h. My approach:

 

Landing speed of 350 km / h

Flaps 45 degrees

The inclination of 0-4 degrees

engine speed 90

Air brakes off - too slowed the aircraft - too big bank at the speed of 350 km / h.

 

Braking parachute ejected about 1-2 m. The front wheel is not broken, but there is an abnormality in the control panel gear.

 

Very hard to keep the aircraft in a straight position before landing without tilt speed of 350 km / h.

 

The aircraft in the video is visually see his inclination.

 

If the gear withstand greater impact, landing with a braking parachute would uskutečnitelé. The manual says that the gear MiG-21bis was designed to withstand greater impact compared to other aircraft. The aircraft must land smoothly. The video is clear evidence that the MiG-21 has a hard gear to a hard landing.

[CoBlue]

Was used for short runways, but with checking the systems after such a landing.

only in German :

http://forums.eagle.ru/showpost.php?p=2311644&postcount=10

[simapajik]

Each version of the MiG-21, according to real manuals another landing speed. According to the manual LN MiG-21bis gear is designed for hard landing. The DCS must with Mig 21 landing smoothly. This is just the opposite.

 

The video shows the hard impact with the runway. Real MiG-21bis withstand greater impact than in the simulation. Please developers. Adjustment attention gear MiG-21bis.

Edited August 14, 2016 by simapajik

[Buzzles]

Designed for rough landings (ie, rough surfaces) is not the same as hard landings which comprise of slamming it down into the runway.

[Frederf]

Indeed the manual says limit 7300 kg landing to 3% of all landings, 6800 kg otherwise, 6500 kg if BLC not used. Landings exceeding the normal type require inspection of the landing gear.

 

I don't know if that's landing gear or brakes, probably a bit of both. Some of the motivation is longevity of the hardware beyond a single mission. I can't say how delicate or not the gear should be at a single landing. I've always been able to land quite easily not to break the gear because I haven't been even close to needing the parachute, not to speak of deploying it while still airborne.

 

The short field technique of deploying at a low height is absolutely real and if it's practically impossible to do it without breaking something then there is something wrong.

[Golo]

It is possible, Ive done it few times myself without any gear damage.

You still have to be careful not to release it too high or with too high vertical speed, but it is definetly possible.

[simapajik]

I have only Czech guide. I will try to translate.

 

"Use and piloting technique."

 

MiG-21M (engine R11F2S-300)

Mig-21MF (engine R13-300)

 

In exceptional cases (long budget) can be omitted braking parachute to shorten the length of the paddock in the air at a height below 1 meter (when sufficient Additionally, in the years running SPS), followed by a tour gear (this landing must be entered on the journal of preparing the aircraft).

[simapajik]

I took the record from my landing. Please watch outside view F2. Attempted very smooth landing. Braking parachute ejected at a height below 1 meter. Optically seen that the front gear and the left gear destroyed. Check the gear control panel in the cockpit.

 

Please what is done wrong? Please comment.

landing2.trk

[Golo]

Yea, you are totally right, I just tested it again in this version and its way off.

In previous updates I was flying 21 lot, and it was fine as I was saying.

Now the gears cant stand harder landing.

MiG-21 is getting from 10 to 5 and not just in this.

[Frederf]

It's a little heavy (1500L) but otherwise fine.

 

At the moment of chute release I record

304 km/h

432m (430m)

4° pitch

1° bank

6.0° AOA

-2.5m/s vertical rate

 

I estimate 1.5 tyre diameter (800mm x 1.5) between bottom of tyre and runway so 1.6m. That sounds more than the 1m max but the video is beginning deployment possibly 3-4m height without issue.

 

By the moment of contact within 1 second the parachute has not fully deployed and the measurements are:

288 km/h

431m

-1° pitch

°1 bank

1.3° AOA

-3.5m/s vertical rate

 

In a very short time the pitch has changed a lot. Nose tyre has gone from being 0.4m above main tyre to contacting first. Vertical rate has increased. At the bottom of gear shock travel measured vertical load is 10.9G. There is a pronounced bounce as all tyres leave the runway.

 

In short I think it is perfectly expected that the landing gear is damaged given the attitude and vertical rate in the track. What I don't understand is why deploying the chute results in such a huge pitch down moment. The airplane weights about 7MT when landing and has significant rotational inertia in the lateral axis. There's nothing about the geometry of the drag chute that should torque the pitch down so forcefully. In the video the nose is kept up the entire time. In fact the airplane departs in roll well before pitch.

 

At these low Mach numbers the airplane should not stall until ~200km/h at an AOA well off the UUA-1 gauge scale. And even then it should depart in roll control before pitch. The slowing by drag chute from 304 to 280 shouldn't considerably change pitch or pitch control.

[simapajik]

[ame]

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Gentlemen, we know that DCS World is a simulation. Among the advantages of the Mig-21 include hard gear. In the simulation we have to land smoothly. On the videos, the layman can see that it is very hard landing gear on. These videos are old. I've never seen landing another fighter like Mig-21 on video. Landing maneuver Mig-21 is unique. Message to all pilots LN MiG-21bis and developer of LN fighter. Do you agree with me? It is a big problem to adjust operational limitation gear?

 

Thank you very much to all :thumbup:

[simapajik]

Yes, I tried to land an airplane without a balancing by trim. Trim neutral. Landing is not so hard, but the front gear is still damaged.

 

Fuel 25%

Pitch 2

Speed of 300 km / h

full flaps

Air brake on

 

Gear is more sensitive than previous versions DCS. If I see a lot of bugs around the module for a long time, why not be an error in gear. Naposlet we were told that the radar is working perfectly well. At the end it was found that the radar beam is not stabilized, and hence can not detect a target in front of him. Aso-2 ever accidentally not releasing chaff and flares.

Why do you think that the fault is not in gear. ??? :lol::thumbup:

[simapajik]

1.I am writing on the front wheel. Which is very sensitive.

2. Using trim, flaps, brakes, higher speed, lower speed - still front wheel damaged. Look at the video as the front wheel bounces off the runway.

 

There are three options.

1.I'm failures in the landing.

2. Flight dynamics of the airplane when you release the drag chute. (The airplane is hard-pressed to runway).

3. Front wheel is very sensitive.

 

Everything just speculation. Please practical demonstration in the simulation DCS World 1.5.4, MiG-21bis landing maneuver using a drag chute, as the real video. :thumbup:

[simapajik]

Frederf wrote...

 

The big difference in the video to DCS is the fact that the airplane is not violently pitched down by the chute and the nose wheel can even be off the ground after main touchdown. It's as if the DCS chute is modeled as a rigid object extending directly aft instead of by airflow. The nose down torque is insane.

 

The problem is in the flight dynamics of the aircraft in the discharge chute. The airplane is hard pressed to the ground, causing the destruction of the front wheel. :smartass: