Mirage 2000 Tire Burst Speed too low

[Milomindenbinder]

I have more than 1,000 takeoffs and landing (same number fortunately,) in the Mirage IIIO. My Flight Manuals shows the max un-stick speed of 210 KIAS for hot and heavy takeoffs. I have never burst a tire in over 1,000 hours.

 

In the Mirage 2000C I vget tire bursts if on the ground at 170-180 KIAS. This happens if I'm slow to rotate on a touch and go. No biggie, but you really do need to 'touch and go' to avoid tire blowouts. I think it would be realistic to raise the tire burst speed to ~200 KIAS.

 

Thanks RAZBAM for an excellent piece of work - haven't had so much fun since I last flew the Mirage IIIO in 1975!

 

Kind regards,

 

Chris Mills / Flamethrower.

[Azrayen]

Hi

 

The 2000 is a different beast. One of its specifics is retaining the delta formula while on the same time being able to greatly reduce landing speeds vs the M III.

 

I can't recall the exact value but the front gear definitely has a lower max speed than the main gears, and if memory serves this lower speed is below 200kt.

 

Regards

 

Az'

[Milomindenbinder]

Hi Azrayen,

 

Yes, the relaxed stability of the Mirage 2000C allows it to fly at lower speeds.

 

The Mirage IIIO had a limited HUD display - only for weapons operation. I'm really enjoying the Mirage 2000C HUD modes and have made up a special mission to master ILS and TACAN navigation to recover from missions at night and/or in bad weather. Autopilot coupled to the ILS is a great recovery aid.

 

The 'Inverse Drag' of the delta is still there and I have created several flaming holes from looking away from the HUD for ten seconds. The HUD speed cues are a tremendous help.

 

Re tires, nose-wheels generally have lower limits than main-wheels as TO is raise at 120 KIAS (130 KIAS Mirage IIIO) and keep it off the ground on landing to generate drag to slow - very effective. My (trivial) point is that the main-wheels of the 2000C come from the same stable as the IIIO and can take higher speeds. OBTW, the 210 KIAS takeoff is 30 Celsius, 28,000 lbs and a 7,000 foot run - scary! Can send the page of the IIIO flight manual if it is of interest.

 

Thanks for the reply - much appreciated.

 

Kind regards,

 

Chris Mills / Milomindenbinder

[nighthawk2174]

On 7/26/2020 at 1:07 AM, Milomindenbinder said:

I have more than 1,000 takeoffs and landing (same number fortunately,) in the Mirage IIIO. My Flight Manuals shows the max un-stick speed of 210 KIAS for hot and heavy takeoffs. I have never burst a tire in over 1,000 hours.

 

In the Mirage 2000C I vget tire bursts if on the ground at 170-180 KIAS. This happens if I'm slow to rotate on a touch and go. No biggie, but you really do need to 'touch and go' to avoid tire blowouts. I think it would be realistic to raise the tire burst speed to ~200 KIAS.

 

Thanks RAZBAM for an excellent piece of work - haven't had so much fun since I last flew the Mirage IIIO in 1975!

 

Kind regards,

 

Chris Mills / Flamethrower.

I wonder if there is also a safety margin built into that number as well making it a bit higher than that as this is the case in a lot of places.  Thanks for the info.

[Ramsay]

15 hours ago, nighthawk2174 said:

I wonder if there is also a safety margin built into that number as well making it a bit higher than that as this is the case in a lot of places.

 

The RAAF Flight Manual for the Mirage IIIO &IIID has a caution not to lower it's  nose wheel onto the ground at speeds above 190 KIAS.

 

Circuit entry and landing, page 252

Quote

 

CAUTION

The nose wheel limiting speed is 190 KIAS and it should not be lowered at higher speeds.

 

 

Didn't find any issues (blown tyres) testing touch & goes/landing at Akrotiri RWY 28, 20°C, No wind

 

3x Normal MLW* (~9800 kg / ~59%) :- On speed AoA = 145 KIAS

3x Uprated MLW** (~12000 kg / ~73%) :- On speed AoA = 165 KIAS

 

Uprated MLW touch & go testing method

On landing :-

• HUD inverted T aerobrake plus airbrakes until nose wheel drops at ~135 KIAS

• Reset trim

• Engauge AB

• Rotate ~150 KIAS, HUD inverted T level with horizon line

• Main wheels lift clear (VS +100 ft/min) @ ~180 IAS (DCS stiction ?)

 

DCS Open Beta 2.7.3.8494

 

* CLEAN AIRCRAFT + 2050 kg Internal Fuel

** STANDARD AIR-TO-GROUND ( MT Wing Tanks / 4X MK-82S) + 2600 kg Internal Fuel

 

Edited July 12, 2021 by Ramsay
Test for blown tyres at uprated MLW

[Preendog]

This is a thing.  I just tested 20 times.  The wheels popped at speeds between 160 and 220.

The tires will pop at any speed above 160 if you give it enough time.  This happens with any weight loadout, online and offline, with any stick position, while braking, skidding or just rolling forward.  My brakes are bound to keys, so it's not an axis issue.

 

To replicate:  Roll steadily at any speed above 160 and wait.  

 

I think it has to do with how the M2000 jiggles a lot while taxing.  The plane's speed is 189 here, but the instantaneous speeds of the wheels jitter randomly as the plane jiggles.  If a wheel exceeds 220 for even one physics step, it pops.  

 

 

 

Edited November 23, 2021 by Preendog
brevity

[Bananabrai]

I was also wondering about this a couple of weeks ago. I was flying the Mirage pretty often 2 years ago and never had problems.

But now it seems like an issue. Mostly I am taking heavy A-G loadouts, but within the given limits, but it happens also for with lighter loadouts.
I normaly use the Cyprian runway of Paphos... don't know if thats maybe a thing? Some runways are maybe rougher than others?

[Preendog]

All runways and roads in DCS have the same bumpiness, including dirt roads.  Taxi jiggle is module-specific.

Video of all tires popping at about 170kts, empty, 10% fuel:

 

 

Edited November 23, 2021 by Preendog

[jojo]

1 hour ago, Preendog said:

All runways and roads in DCS have the same bumpiness, including dirt roads.  Taxi jiggle is module-specific.

Video of all tires popping at about 170kts, empty, 10% fuel:

 

 

 

And what are you waiting for when rolling nose down at 170kt ?
Rotate at 120kt when light, 150kt when heavy...no problem !

[Foogle]

42 minutes ago, jojo said:

And what are you waiting for when rolling nose down at 170kt ?
Rotate at 120kt when light, 150kt when heavy...no problem !

It's a test to see the speed at which the tires pop and if its related to aircraft weight.

[arnokm]

Max Speed on Mirage 2000-D front wheel: 199kt. Could be different on 2000-C ?

Source:  https://www.defense.gouv.fr/content/download/515375/8673216/A-2015-016-I.pdf

p12: L’utilisation du parachute frein est limitée à la position trois points avec Vi ≤ 210 kt. La vitesse maximale de roulage de la roue avant équipée de pneus Michelin est 199 kt.