1050 Nautical Mile HI/LO/HI Strike

[FuY]

I just did a 2100 NM, HI/LO/HI Strike 
with tripple bag, 4x mk82snakeeye and 2x Magic II

I never droped anything but the 4 bombs @ the target which was 1050 NM away from my starting postion. 
after flying back i still had 500 KG of fuel. 

There was no wind on the map. 

Are you sure this is realistic ? 

[Preendog]

Wikipedia says ferry range is 1800nm, so it's in the ballpark at least.

That might just be with 2 tanks, though. Someone in the know can correct me, but I can't find any pics of this M2000 or M2000-5 carrying 3 tanks. It may be unusual IRL. 

Edited December 16, 2021 by Preendog

[Ramsay]

On 12/16/2021 at 3:39 AM, FuY said:

Are you sure this is realistic ? 

As said, it's in the ball park. IIRC Razbam have said they'll re-check the FM, etc. but are focused on other aspects of the Mirage ATM. 

Detail:

This is just to give you an idea of where the Mirage's performance is at the moment compared to the engine specs and TSFC figures from Forecast International 2007:

Quote

 

M53-P2 specs from Forecast International 2007

• Dry thrust = 64.49 kN
• A/B thrust = 95.18 kN

• Dry specific fuel consumption = 25.497 mg/Ns
• A/B specific fuel consumption = 58.643 mg/Ns

 

From these, approx. fuel burn rates per hour might be:

• Dry 64.49 * 25.497 = 1,644 kg/hr = 27.4 kg/min
• A/B 95.18 * 58.643 = 5,582 kg/hr = 93.0 kg/min

and Max Endurance (3 external tanks = 7125 kg of fuel) is

• Dry 7125/1,644 hr = 4.33 hr = 4 hr 20 min (dry)
• A/B 7125/5,582 hr = 1.28 hr = 1 hr 16 min (A/B)

A sanity check in DCS Open Beta 2.7.8.16140 showed the Mk-82 Long Range loadout had

• a similar dry fuel burn to the above i.e. ~30 kg/min
• while wet fuel burn was twice that expected i.e. 182 kg/min

Quote

 

In game, Mk-82 Long Range loadout: 

322 KIAS / 0.84 Mach @ 30,000 ft (500 knots GS)
Dry Fuel Burn = 30 kg/min = 1,800 kg/hr
Dry Endurance = 7125/1800 = 3.95 hr = 3 hr 57 min
Dry Range = ~1,975 NM (3.95 * 500)

385 KIAS / 0.99 Mach @ 30,000 ft (584 knots GS)
Wet Fuel Burn = 182 kg/min = 10,920 kg/hr
Wet Endurance = 7125/10920 = 0.65 hr = 39 min
Wet Range = ~379 NM (0.65 * 584)

 

There are better informed members i.e. aeronautical engineers, etc. who can pick apart my theory crafting, but IMHO, we'll need to wait for Razbam to work with their SME's.

Edited December 17, 2021 by Ramsay

[jojo]

12 hours ago, Preendog said:

Wikipedia says ferry range is 1800nm, so it's in the ballpark at least.

That might just be with 2 tanks, though. Someone in the know can correct me, but I can't find any pics of this M2000 or M2000-5 carrying 3 tanks. It may be unusual IRL. 

 

It’s definitely a thing for Mirage 2000-5F, it’s their “war” CAP or long range escort configuration.

Unlike Mirage 2000C, Mirage 2000-5F can selectively drop fuel tanks, for instance dropping wing tanks and keeping fuselage tank.

[jojo]

On 12/16/2021 at 7:39 AM, FuY said:

I just did a 2100 NM, HI/LO/HI Strike 
with tripple bag, 4x mk82snakeeye and 2x Magic II

I never droped anything but the 4 bombs @ the target which was 1050 NM away from my starting postion. 
after flying back i still had 500 KG of fuel. 

There was no wind on the map. 

Are you sure this is realistic ? 

I would say no, because:
- it’s an overweight configuration (it would be more “realistic” to take empty fuselage tank and perform in flight refuelling)
- there is always strong winds in high altitude in real life

But congratulations for your endurance
How long did it takes ? What were your acquise altitude and cruise speed ?

Did you do constant/ step climb ?

[jojo]

1 hour ago, Ramsay said:

As said, it's in the ball park. IIRC Razbam have said they'll re-check the FM, etc. but are focused on other aspects of the Mirage ATM. 

Detail:

This is just to give you an idea of where the Mirage's performance is at the moment compared to the engine specs and TSFC figures from Forecast International 2007:

From these, approx. fuel burn rates per hour might be:

• Dry 64.49 * 25.497 = 1,644 kg/hr = 27.4 kg/min
• A/B 95.18 * 58.643 = 5,582 kg/hr = 93.0 kg/min

and Max Endurance (3 external tanks = 7125 kg of fuel) is

• Dry 7125/1,644 hr = 4.33 hr = 4 hr 20 min (dry)
• A/B 7125/5,582 hr = 1.28 hr = 1 hr 16 min (A/B)

A sanity check in DCS Open Beta 2.7.8.16140 showed the Mk-82 Long Range loadout had

• a similar dry fuel burn to the above i.e. ~30 kg/min
• while wet fuel burn was twice that expected i.e. 182 kg/min

There are better informed members i.e. aeronautical engineers, etc. who can pick apart my theory crafting, but IMHO, we'll need to wait for Razbam to work with their SME's.

 

Sorry, but your computation is wrong.

1- SFC is actually 25.497mg/N.s => 64490N*0.025497g*60s = 98658g/mn = 98,7kg/mn…which is more in line with low altitude maximum dry thrust in game (That’s 5919kg/hr).
2- at high altitude, the drag is less because of lower air density, but so is the thrust ! You don’t get maximum low altitude thrust when you climb !

[arnokm]

Above is a model from Onera.

With a very heavy load, best Autonomy is obtained at 35kft / 0.8M.

After the strike, the RTB could be done at 40kf / 0.85M for best Autonomy.

Edited December 17, 2021 by arnokm

[Ramsay]

On 12/17/2021 at 7:15 AM, jojo said:

Sorry, but your computation is wrong.

1- SFC is actually 25.497mg/N.s => 64490N*0.025497g*60s = 98658g/mn = 98,7kg/mn…which is more in line with low altitude maximum dry thrust in game (That’s 5919kg/hr).
2- at high altitude, the drag is less because of lower air density, but so is the thrust ! You don’t get maximum low altitude thrust when you climb !

Thanks, I was having difficulty with the unfamiliar units, so the error was not totally unexpected.

Re-testing fuel consumption at Sea Level (2,000 ft) in game, the values are much closer now

• Dry 98.7 kg/min vs 95 kg/min in game
• Wet 334.9 kg/min vs 300 kg/min in game (perhaps flow is limited by the fuel pumps)

Calculations/details:

Spoiler

Approx. fuel burn rates per hour at sea level ? are

Dry 64.490 * 25.497 * 60 sec = 98.7 kg/min (5,920 kg/h)
A/B 95.180 * 58.643 * 60 sec = 334.9 kg/min (20,090 kg/h)

Endurance (Mk-82 Long Range loadout with 3 external tanks = 7125 kg of fuel)

Dry 7125/5,920 hr = 1.20 hr = 1 hr 12 min (dry)
A/B 7125/20,090 hr = 0.35 hr = 21 min (A/B)

In game, Mk-82 Long Range loadout: 

At Sea Level
556 KIAS / 0.87 Mach @ 2,000 ft (574 knots GS)
Dry Fuel Burn = 95 kg/min = 5,700 kg/hr
Dry Endurance = 7125/5700 = 1.25 hr = 1 hr 15 min
Dry Range = ~718 NM (1.25 * 574)

601 KIAS / 0.94 Mach @ 2,000 ft (619 knots GS)
Wet Fuel Burn = 300 kg/min = 18,000 kg/hr
Wet Endurance = 7125/18000 = 0.40 hr = 24 min
Wet Range = ~245 NM (0.40 * 619)

At Altitude
322 KIAS / 0.84 Mach @ 30,000 ft (500 knots GS)
Dry Fuel Burn = 30 kg/min = 1,800 kg/hr
Dry Endurance = 7125/1800 = 3.95 hr = 3 hr 57 min
Dry Range = ~1,975 NM (3.95 * 500)

385 KIAS / 0.99 Mach @ 30,000 ft (584 knots GS)
Wet Fuel Burn = 182 kg/min = 10,920 kg/hr
Wet Endurance = 7125/10920 = 0.65 hr = 39 min
Wet Range = ~379 NM (0.65 * 584)

 

Edited December 18, 2021 by Ramsay
Spelling/typo