Global Supertanker / Airtanker Ops

[Mawea]

While looking for new liveries to create, I came across the Global Supertanker (GST or Tanker 944) and decided to repaint it so we can fly it in PSX.NET, both on its own and with MSFS2024. In a future update by Gray of PSX.NET the repaint I did of the N744ST will be included.

System Overview
The model file included is based on a Japan Airlines (JAL) 747 configuration, with adjustments made using cockpit screenshots. No tail tanks, registration markings, RMIs. I used the NG FMS to enter fire positions via the FIX page, although this feature is not confirmed with the actual aircraft, also it was converted into a freighter and had no nose door, not sure how the Doors synoptic page would look like, is the BCF represented in PSX?

The real aircraft featured a drop system panel and two FM radios on the lower pedestal for coordination with ground firefighters.

The drop system consists of two pressurized tank groups five on each side (left and right) and 4 drop valves, with a total capacity of 19,400 U.S. gallons (approximately 74,000 liters). The empty tank system weighs around 19,600 lb (8,900 kg), and a full load of retardant can weigh up to ~150,000 lb (68,000 kg).

The system is designed to minimize center of gravity (CG) shift between a fully loaded and an empty configuration, allowing the aircraft to remain stable throughout the drop sequence.

Operational Procedures and Handling
To better simulate the Global Supertanker's real-world mission profile, I studied firefighting operations through documentation, video footage, and interviews with flight and ground crews.

Fire Traffic Area (FTA) Procedures
Airtankers operate under strict rules when entering a Fire Traffic Area (FTA). These are defined airspace zones with specific entry and communication procedures to ensure safe and coordinated aerial firefighting.

The FTA typically extends to 2,500 feet AGL, within a 5-nautical-mile radius centered on the fire.
Entry requires clearance from the Air Attack aircraft, which supervises the operation and communicates with the Incident Commander (IC) on the ground.

FTA patterns:
Air Attack aircraft orbit clockwise at 2,500 feet AGL or above.
Tankers orbit counterclockwise at 1,500 feet AGL or above.
A minimum of 1,000 feet vertical separation is maintained between the two.
Tactical Flight Parameters
Airtanker maneuvering altitude is typically between 500 and 1,000 feet AGL.
Drops are made between 200 and 300 feet AGL at about 150 knots.
Helicopters have a ceiling maneuvering in the FTA of 500'

A full load drop takes up to 13 seconds but depends on the selected coverage level. The Global Supertanker supports adjustable coverage levels (CL3 to CL8), which refer to gallons of retardant released per 100 square feet. The system allows for fine-tuning through pressure adjustments and valve settings to match the desired CL.

The speed limit for entering the FTA orbit is 150 KIAS. If the aircraft is too heavy to maintain that speed, the pilot must inform Air Attack and report the minimum safe maneuvering speed.
Typical tactical takeoff weight is approximately 655,000 lb, including retardant and about 2.5 hours of fuel.
Communication and Drop Coordination
Initial radio contact with Air Attack must be made at least 12 nautical miles from the fire center. If communication cannot be established, the aircraft must hold at 7 nautical miles until contact is made.

Once cleared into the FTA, VLATs are guided by a lead or chase aircraft, which aligns them with the drop line. Visual markers such as smoke and coordinated radio calls indicate the start point for the drop.

Attached Situ, model and scenery files
Regarding the situ below, you are positioned south of the Camp Fire (Nov 2018), near Paradise, CA (N3943.9 W121 34.6), in a holding pattern ready to enter the FTA. Prepare for the drop, I've pulled the aural warning CBs to mute the warnings, similar to what you see in the video footage. With flaps at 30, gear up, and flying at low levels, expect a lot of alerts blaring at you.
Dropline Heading: 350, Drop Altitude: 1700'-1800' MSL
To create the screenshot, I added basic flames and smoke to represent the wildfire and am sharing it with you here. Just unzip and place the mawea-fire folder into your MSFS 2024 Community folder.

Flying a 747 at low speeds and altitudes well outside its normal flight envelope is highly demanding. Real-world footage of the Supertanker in action is impressive. I hope to spark some fire in you to fly low over hilly terrain

If you have any corrections, technical insights, or operational details to add, I'd be glad to incorporate them.

Best regards
Jay

Situ and model
https://www.dropbox.com/scl/fo/nsmt5b1tvjaolxqddbtrt/AKygs0o4gwixD7k9xqQvzqg?rlkey=s5309qz4hxxmkhqzx0yd8vn4r&st=bcaelpo9&dl=0

msfs24 fire scene
https://www.dropbox.com/scl/fo/v8wsqmo32d4ecj8sfz4j9/AMWM8EA7LlAYZHLQISeD_Lw?rlkey=suf1ag2jeszt6c3gm531cf04f&st=3ds178dk&dl=0

"New fires in August 2025"
-------------------
DILLON Fire: N4132.9 W12333.8
LOG Fire: N4125.8 W12316.9
SWIFT COMPLEX Fire: N4056.4 W12252.5
BLUE Fire: N4147.7 W12312.2

[macroflight]

The drop system consists of two pressurized tank groups five on each side (left and right) and 4 drop valves, with a total capacity of 19,400 U.S. gallons (approximately 74,000 liters). The empty tank system weighs around 19,600 lb (8,900 kg), and a full load of retardant can weigh up to ~150,000 lb (68,000 kg).

The system is designed to minimize center of gravity (CG) shift between a fully loaded and an empty configuration, allowing the aircraft to remain stable throughout the drop sequence.

Very impressive!

Do you simulate the actual drop already? Otherwise it would be relatively easy to write a small custom addon for this that when triggered (e.g by some rarely-used cockpit switch or an addon= network message) would reduce ZFW by 74t over a realistic time period.

[Mawea]

Thanks. No, not so far, I thought only Hardy could help with the drop and loss of the weight. Help would be very much appreciated. 

[B747-400]

Great idea 

[macroflight]

Thanks. No, not so far, I thought only Hardy could help with the drop and loss of the weight. Help would be very much appreciated. 

Quick'n'dirty hack done: https://github.com/macroflight/psxhacks/blob/testing/psx_water_drop.py

Code Select Expand

$ python psx_water_drop.py

    1: Set your ZFW without water load

    2: Enter the amount of water to load below

    3: Enter the amount of water to drop per attack/trigger press

    4: Enter the drop rate in kg/s

    5: Choose fast or realistic (30 min for a full load) fill time

    6: Take off and fly to the fire

    7: Trigger water drops by pressing teh Captain's PTT on the
    glareshield (LcpPttCp) OR sending an addon=WATERBOMBER message to
    the PSX network

    8: When the last water has been dropped, the system resets and you
    can choose a new load

Hint: it is possible to cheat and refill the water in the air :)


Waiting for PSX connection...
Connected to PSX!
Connected to PSX 10.182 NG as client #51
Trigger pressed (LcpPttCp)
Simulation started
Drop system reset!
Water load (kg): 47000
Water drop per trigger (kg): 12000
Water drop rate (kg/s) [valid: 950-4000]: 3000
Water fill rate - (R)ealistic or (F)ast: F
Water loading started (47000.0 kg)
ZFW is now 237000.1 kg, remaining water to load: 0.0 kg
WATER LOADING COMPLETE. GO FIGHT A FIRE, CAPTAIN!
Water remaining: 47000.0 kg
Press trigger to drop
Trigger pressed (LcpPttCp)
Dropping water!
ZFW is now 234000.1 kg, water onboard is 44000.0 kg
ZFW is now 231000.1 kg, water onboard is 41000.0 kg
ZFW is now 228000.1 kg, water onboard is 38000.0 kg
ZFW is now 225000.1 kg, water onboard is 35000.0 kg
Drop complete!
Water remaining: 35000.0 kg
Press trigger to drop
Trigger pressed (LcpPttCp)
Dropping water!
ZFW is now 222000.1 kg, water onboard is 32000.0 kg
ZFW is now 219000.1 kg, water onboard is 29000.0 kg
ZFW is now 216000.1 kg, water onboard is 26000.0 kg
ZFW is now 213000.1 kg, water onboard is 23000.0 kg
Drop complete!
Water remaining: 23000.0 kg
Press trigger to drop
Trigger pressed (addon)
Dropping water!
ZFW is now 210000.1 kg, water onboard is 20000.0 kg
ZFW is now 207000.1 kg, water onboard is 17000.0 kg
ZFW is now 204000.1 kg, water onboard is 14000.0 kg
ZFW is now 201000.1 kg, water onboard is 11000.0 kg
Drop complete!
Water remaining: 11000.0 kg
Press trigger to drop
Trigger pressed (LcpPttCp)
Dropping water!
ZFW is now 198000.1 kg, water onboard is 8000.0 kg
ZFW is now 195000.1 kg, water onboard is 5000.0 kg
ZFW is now 192000.1 kg, water onboard is 2000.0 kg
ZFW is now 190000.1 kg, water onboard is 0.0 kg
Drop complete!
Drop system reset!
Water load (kg):



[macroflight]

That's a BIG fire...  A tragedy, both for the people on the ground and my fps.  Interesting flying though.

[Mawea]

Thanks for the drop.py! Looking forward playing with it. Unfortunately I am out for work until the weekend. Would this also work with PSX only?

About the size of the scene, I make a smaller one for better performance.

[Mawea]

Here is the layout of the tanks. See the first five tanks are retardant/water and in the rear the pressurized air tanks.




And the Drop System Panel

[Gary Oliver]

I look forward to Macroflights first foray into a UI with the 'PSX.Python.DropPanel' project

[macroflight]

Would this also work with PSX only?

Yes. The Python code only talks to PSX.

[Mawea]

Really nice, thanks macroflight. Was able to test it today on my laptop. Wasn't aware of hoppies psx.py but once I figured that out psx connected to your py script. I am a fan of the inflight refill thanks for the feature and your effort!

*edit
I double checked the numbers drop takes  ~13 sec of a full load with CL8-10 which would be around 5600-5700kg/s. And the retardant reload takes approximately 20 minutes. The turnaround takes 30 min in total.

[macroflight]

I look forward to Macroflights first foray into a UI with the 'PSX.Python.DropPanel' project

I don't see what's wrong with my text UIs... A first prototype 

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[macroflight]

I double checked the numbers drop takes  ~13 sec of a full load with CL8-10 which would be around 5600-5700kg/s. And the retardant reload takes approximately 20 minutes. The turnaround takes 30 min in total.

I just pushed an updated version that uses those numbers.

[Mawea]

Hi macroflight,
today I had time to test your water_drop.py It is really FUN, thank you!

I removed most of the CAMP Fire effects should be more frame rate friendly now! Added the latest Cal Fires (SwiftComplex, Log, Blue and Dillon) from today. Check here for locations https://firms.modaps.eosdis.nasa.gov/usfs/map/#d:24hrs;@-122.91,41.34,10.00z
or in the latest SwiftComplex situ also in the link below the Fix Page has the fires (max 4!) so one is missing.




here is the updated fire scene including all fires:
https://www.dropbox.com/scl/fo/v8wsqmo32d4ecj8sfz4j9/AMWM8EA7LlAYZHLQISeD_Lw?rlkey=6s17axxupuldimrblm8trg3xb&dl=0