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Hello ! I'd love to hear how you approach fuel calculations in a combat environment, and more specifically the minimum fuel for landing or in-flight refueling, a quantity of fuel that is closely linked to the diversion airfields you've chosen. To kick-start the discussion, here's a short article introducing the concept of diversion airfields in the context of military aviation. Enjoy your reading! Diversion Airfields for HPMA: Introduction In military aviation, safety and mission effectiveness depend heavily on having well-planned contingency options. Diversion airfields are critical elements in ensuring that HPMA (High-Performance Military Aircraft, i.e. fighter jets) have a safe haven in case their primary destination becomes unavailable. These airfields act as lifelines, particularly in dynamic operational environments where emergencies, adverse weather, or other unforeseen factors (like enemy military action) can disrupt mission plans. I'll introduce here the purpose of diversion airfields, the principles of fuel planning, and the additional considerations that ensure mission success, before a next article that will apply it to the Afghan case. Diversion Airfields: Purpose and Selection Diversion airfields are carefully chosen to meet the operational demands of HPMA. These selections are based on factors such as proximity to the mission area, runway capabilities, support infrastructure, and overall security. For military jets, runway length is a paramount consideration, as the runway must accommodate the high speeds and potential heavy payloads upon landing. The availability of military-grade fuel, maintenance services, and munitions handling facilities further influence the choice of suitable diversion airfields. In high-threat zones, security becomes an equally important factor. Diversion airfields in such areas must be secure from enemy activity and equipped with defensive measures to protect personnel and assets. AIP page for Kabul International Airfield stating that military grade F-34 fuel is available: it's a suitable diversion option in terms of fuel. Another crucial aspect of diversion airfield planning is the strategic placement of at least two suitable options near the primary recovery base. This ensures operational flexibility and contingency coverage, as the fuel requirements upon arrival at the primary airfield depend not only on its weather conditions but also on the conditions at these alternate diversion sites. This approach mitigates risks and enhances overall mission safety. However, since alternate airfields choice is a risk management decision, the rules can be changed depending on the actual operational situation by a commander with the sufficient level of authority. For example, we can imagine that reducing the alternates option to a single airfield can be decided, or even to no alternate options, for carrier operations at large for example (also called "blue water ops"). Fuel Planning and Minimum Reserves Given their high instantaneous fuel consumption, fuel planning for military jets needs to be a meticulous process that balances operational requirements with safety. The calculation begins with estimating cruise fuel burn, which is the amount needed to reach the diversion airfield under normal cruise conditions. Reserve fuel is then added to account for potential deviations, holding patterns, or emergencies. These reserves are critical, as they allow pilots to execute specific procedures after reaching the diversion airfield. National regulations often dictate the specific procedures enabled by minimum fuel reserves. For example, in France, the minimum fuel for VMC/day operations ensures the ability to perform a go-around procedure followed by 10 minutes of low-level navigation before bailout. For IMC/night operations, the reserves account for a go-around, a second IMC procedure, another go-around, and an immediate bailout. In contrast, civilian aviation adheres to stricter fuel reserve rules, such as carrying enough fuel to reach an alternate airport plus 45 minutes of holding time. While effective for commercial airliners, this approach is totally impractical for high-performance military aircraft. Following such rules would leave combat aircraft with virtually no fuel for combat operations. Instead, military fuel planning emphasizes adaptability, incorporating real-time mission demands and environmental conditions. Note that additional fuel reserves are often allocated to account for local circumstances. For example, operations may require extended holding times due to heavy air traffic or regular runway closures. For example, in Afghanistan these closures could result from routine inspections, such as those conducted after mortar attacks on airfields. By anticipating these factors, mission planners ensure that pilots have the fuel needed to navigate complex and unpredictable scenarios. Military personnel taking cover in a bunker during a rocket attack at Kandahar airbase. Essential Diversion Data for Mission Planning The effective use of diversion airfields relies on having accurate and comprehensive data. Inflight guides and mission planning tools need to be created in order to provide essential information to ensure safe and efficient in-flight decision-making. Key data points include: Relative Location: information on range and heading to diversion airfields helps pilots quickly assess options. For example, Creech AFB is located 36 NM from Nellis AFB on a heading of 290°, while Edwards AFB is 160 NM away at 225° (see picture below). Runway Dimensions: runway length and orientation are critical for landing and takeoff. Diversion airfields like Edwards AFB offer long runways (15,000 feet), while others like Creech AFB provide shorter options (9,000 feet) suitable for day/VFR conditions . Navigation Aids (NAVAIDs): TACAN or VOR frequencies allow for precise navigation. For instance, Creech AFB operates on TACAN Channel 87 (INS), while Edwards AFB uses Channel 111 (EDW) . Ideal Transit Altitude: specified altitudes optimize fuel consumption and air traffic deconfliction. For example, en route altitudes to diversion bases in the Red Flag exercise range from FL190 to FL250, depending on the distance . Fuel Consumption for Transit: guides often include fuel usage for specific routes. For example, transitioning to Fallon NAS from a specified location requires 5,000 pounds of fuel with reserves . Example of diversion data for Nellis. This picture is not specific to an aircraft type. Understanding the assumptions underlying these fuel calculations is also vital for their effective application. Assumptions often include factors such as the aircraft’s load, weather conditions, expected airspeeds, and transit altitude. Assumptions about payload configuration will impact fuel burn rates, particularly for aircraft carrying external stores. By knowing these underlying assumptions, pilots can adjust calculations to reflect real-world conditions and adjust the fuel to the closest necessity. Detailed assumptions made for fuel calculation by a A-10 crews for a live fire exercise. Another important consideration is how this data is presented. Diversion data is typically displayed in either tables or graphical representations. Tables provide structured, detailed information such as range, headings, runway lengths, and fuel requirements. However, graphical presentations, such as maps with overlayed annotations or visualized flight paths, are often more effective in operational contexts. A visual representation allows pilots to quickly grasp critical information, including the relative positions of airfields and key navigation details. This is particularly useful in high-stress situations where rapid decision-making is essential. While tables remain a valuable planning tool, graphical presentations offer a clearer, more intuitive way to process information during flight operations. Another example of divert data presented in a table: while all the information if readily available, it's certainly less easy to use in flight than a schematic representation. These data points, combined with mission-specific factors, enable pilots and planners to make informed decisions. By integrating this information into pre-flight planning and real-time operations, military aviation maintains its focus on safety and mission success. As a conclusion, we can say that developing accurate diversion data and graphical kneeboard pictures for every deployment base is a mandatory step to improving mission planning and in-flight diversion execution. These resources ensure that pilots can make efficient and reliable decisions, both on the ground and in-flight. In a following post, I will give you an example by as creating detailed diversion data for operations in Afghanistan, focusing particularly on Kandahar.

I am running DCS world beta 2.7.9.18080, single player, and I am finding too low levels of fuel at the start of missions / campaigns. I initially noticed it in DCS Liberation, but I did a few tests without Liberation to exclude this as as cause. Example 1: Mission editor - a10C II at Batumi airport with no weapons. In mission editor it shows 100% fuel, after starting the fuel gauge shows only up to 2 (six is maximum) Example 2: A10C II instant action free flight - in this mission the fuel gauge shows less than 0.5 fuel. As this mission is intended to fly around, I would expect a high level of fuel (and almost no weapons). So another indication that there is something wrong with the fuel calculation or fuel gauge or something related. Example 3 A10C II instant action CAS Nevada - near zero fuel at the start of the mission mission editor fuel test.miz

Hi Fellow Pilots, I want to get more in to flight planning with the missions I create for myself in the Mission Editor. I want to be able to calculate total route length, estimated fuel usage between Waypoints, speed changes for waypoint eta's etc. Perhaps even Fuel usage at higher/lower altitudes. Obviously, there is the in-Flight FPAS tool, but that is not enough and I do not have access to it I am not sure whether this is possible within DCS. I also have a fully licensed copy CombatFlite if anyone knows if it is possible to do that in there Thank you for your attention Toni

Part of the startup procedure is to sett the "fuel delimiter valve" rocker into the upward position (on/open). I have flown the module in SP and MP now since early release and having this valve either OPEN or CLOSED has had zero effect on the module behaviour and consequence states. Not in excess maneuvers, not in limit maneuvers, not in positive or negative g's, not in damage states, not in anything noticeable where it should result in a different turbine behaviour (to the point of fault). So it this actually background modelled in any way or is this (as of yet) just an animated rocker in the cockpit render? Which is not a problem either way, just some clarification would be helpfull. There is also no need for a trackfile, since you cannot "manufacture" a few small ones for the variety of testing scenarios, maneuvers and states applied. Furthermore since there is a noticeable difference in many things between SP and MP with the module, which can be a little bit confusing sometimes.

Okay everyone thanks to @Middlefart for his main code, my wife for her expertise, helping me with this code for everyone looking for the F-16 Total Fuel gauge. All you need to do is add your code for your motors for the FWD/AFT pointers and your backlighting for your gauge. Easy and done! Hope this helps everyone!! This does work great on my seeeduino XIAO controller (DEFAULT_SERIAL only). Mega, nano, etc will work with IRQ_SERIAL. /* F-16 Total Fuel Gauge Thanks to: Middlefart (Original code), Fusion and Fusion's Wife (software engineer) Code is for the 128x32 oled i2c display. All you have to do is add your motor pins and guage backlight pins if desired. Hope this helps others! DCS-BIOS has made things far easier for DCS than software made to drive simulator components in FalconBMS. Glad to be apart of the DCS world. Matt "Fusion" G. */ //#define DCSBIOS_DEFAULT_SERIAL #define DCSBIOS_DEFAULT_SERIAL #include "DcsBios.h" #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include "characters.h" #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 32 // OLED display height, in pixels // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins) #define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin) Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); int AB; float Value1; float Value2; float Value3; float Total; unsigned long time = 0; unsigned int i = 0; //Comment for barometric pressure #define ALTIMETER int updateInterval = 100; //the number of milliseconds between updates struct scrollDigit { int digit; //The digit that is displayed int y; // The vertical position of the digit }; struct disp { Adafruit_SSD1306 display; int width; int numberOfDigits; scrollDigit digits[5]; }; //disp oled = {Adafruit_SSD1306(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET), 24, 5, {{0,0},{0,0},{0,0},{0,0},{0,0}}}; disp oled = {Adafruit_SSD1306(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET), 16, 5, {{0,0},{0,0},{0,0},{0,0},{0,0}}}; void setup() { if(!oled.display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x32 for(;;); // Don't proceed, loop forever } DcsBios::setup(); } void UpdateDisplay() { oled.display.clearDisplay(); for (int i = 0; i < oled.numberOfDigits; i++) { printScrollingDigit(oled.digits[i].digit, oled.width, oled.digits[i].y, i + 1, &oled); } //Clear the area below the the numbers if we are using the small font if (oled.width == 16) { oled.display.fillRect(0, 30, 127, 7, BLACK); } oled.display.display(); } int YPos() { return ((oled.width + 9) * -1); } void printScrollingDigit(int digit, int width, int y, int pos, disp *oled) { int x = (width * pos) - width + pos + 30; y +=5; switch (digit) { case -1: oled->display.drawBitmap(x, y, c16_0, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_1, 16, 24, 1); break; case 1: oled->display.drawBitmap(x, y, c16_1, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_2, 16, 24, 1); break; case 2: oled->display.drawBitmap(x, y, c16_2, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_3, 16, 24, 1); break; case 3: oled->display.drawBitmap(x, y, c16_3, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_4, 16, 24, 1); break; case 4: oled->display.drawBitmap(x, y, c16_4, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_5, 16, 24, 1); break; case 5: oled->display.drawBitmap(x, y, c16_5, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_6, 16, 24, 1); break; case 6: oled->display.drawBitmap(x, y, c16_6, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_7, 16, 24, 1); break; case 7: oled->display.drawBitmap(x, y, c16_7, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_8, 16, 24, 1); break; case 8: oled->display.drawBitmap(x, y, c16_8, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_9, 16, 24, 1); break; case 9: oled->display.drawBitmap(x, y, c16_9, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_0, 16, 24, 1); break; default: if (pos < 3) { oled->display.drawBitmap(x, y, c16_0, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_1, 16, 24, 1); } else { oled->display.drawBitmap(x, y, c16_0, 16, 24, 1); oled->display.drawBitmap(x, y+25, c16_0, 16, 24, 1); } break; } } void onFueltotalizer10kChange(unsigned int newValue) { unsigned int mappedValue = newValue / 6553; unsigned int y = map(newValue, mappedValue * 6553, mappedValue * 6553 + 6553, 0, YPos()); if (mappedValue == 0) { mappedValue = -1; } #ifdef TEST Serial.println(mappedValue); #endif oled.digits[0].digit = mappedValue; oled.digits[0].y = y; } void onFueltotalizer1kChange(unsigned int newValue) { unsigned int mappedValue = newValue / 6553; unsigned int y = map(newValue, mappedValue * 6553, mappedValue * 6553 + 6553, 0, YPos()); oled.digits[1].digit = mappedValue; oled.digits[1].y = y; } void onFueltotalizer100Change(unsigned int newValue) { unsigned int mappedValue = newValue / 6553; unsigned int y = map(newValue, mappedValue * 6553, mappedValue * 6553 + 6553, 0, YPos()); oled.digits[2].digit = mappedValue; oled.digits[2].y = y; oled.digits[3].digit = 0; oled.digits[3].y = y; oled.digits[4].digit = 0; oled.digits[4].y = y; } DcsBios::IntegerBuffer fueltotalizer10kBuffer(0x44e4, 0xffff, 0, onFueltotalizer10kChange); DcsBios::IntegerBuffer fueltotalizer1kBuffer(0x44e6, 0xffff, 0, onFueltotalizer1kChange); DcsBios::IntegerBuffer fueltotalizer100Buffer(0x44e8, 0xffff, 0, onFueltotalizer100Change); void loop() { DcsBios::loop(); time = millis(); if (time % updateInterval == 0) { UpdateDisplay(); } }

If the airport has unlimited fuel set in the mission editor and the fuel tanks at the airport are destroyed, the airport is still able to refuel the aircraft. I noticed this change recently. It definitely didn't work that way before. Even if unlimited fuel was set at the airport, it was not possible to refuel at the airport after the destruction of all fuel tanks. The planes that had a spawn slot added at the airport were without fuel. The difference between setting up an airport with limited and unrestricted fuel was that if unlimited fuel was set at the airport, all fuel tanks had to be destroyed because the amount of fuel did not decrease. I sincerely hope it's a bug because most missions, even on MP servers, use unlimited fuel settings at the airport. If I take into account the speed of the runway repair, which is 1 hour, and the impossibility of destroying the fuel tanks at the airport, the airports become almost indestructible fortresses. Since I don't remember it being presented somewhere in the changelog as a change, I decided to report it as a bug. The attached track destroys fuel tanks at Sukhumi Airport. The airport has unlimited fuel set. After destroying the fuel tanks, as can be seen on the track, the aircraft that has the spawn slot at the airport has fuel in its tank and I can even refuel the aircraft. The attached track therefore demonstrates the problem described above. Destroy fuel depot with unlimited fuel setting.trk

On Normandy, the port en-Bessin is misnamed as "Les Moulins". Port-en-Bessin was a rather critical port to the allies, as it was the main fuel port for the allies (until Antwerp was taken), as a part of a ship-to-shore transfer system, known as TOMBOLA. Of major note, is that not only is Port-en-Bessin mislabeled on our map, but also mis-modeled as well.

Hi everyone, I've noticed that I find a little off concerning the locations of the warehouses of Andersen AFB and other WSAs on Guam. Firstly, the ammunition - for some reason it's set to some warehouse building and 2 civilian cars next to it (@ N13°34'38", E144°56'02") but there's nothing set to Andersen's actual weapons storage area which is in the north-north-east of Andersen (@ N13°35'40", E144°56'20"), let alone the massive weapons storage area in between Andersen and the North-West field (@ N13°36'30", E144°53'00"). Secondly the fuel, fortunately here it's set to things that make sense (i.e fuel tanks), but it seems there are a few around Andersen have been left out (if they are indeed fuel tanks for aviation fuel, and not diesel or anything else), there's 8 @ N13°35'25", E144°55'17" and a few more to the south west and a further 10 @ N13°34'00", E144°54'50"). For some reason a light-pole/streetlamp is also set as a fuel warehouse @ N13°34'48.90", E144°56'21.60".

Hello, is it possible if someone could model the RCEFS (Reduced size Crashworthy Fuel System) on our apache, maybe use the current Legacy 230 gal tank and change its size to the smaller RCEFS. The RCEFS carries 122-125 gals of fuel compared to the old Legacy fuel tank which carried 230. here are images of the RCEFS. Would love to know if we can get it modelled.null

TL;DR first: The P-51 does not have it's fuel vapor line simulated in DCS. This could have a noticeable affect on how much fuel is recaptured into the fuel tank, as it could be as much as 10 gallons an hour. In close conjunction, the fuselage tank vent line (that the vapor return line feeds into) does not appear to be modeled, quite literally. Track: P-51 Fuel Vapor Return Check.trk I'm going to split this into two different parts. One for the fuel return line, and one for the fuselage tank vent. THE FUEL RETURN LINE: 1) THE ISSUE The DCS P-51 currently does not simulate fuel being returned to the fuel tanks from the carburetor. You can check this yourself by loading the P-51 with full fuel, and run on the left tank until it is empty. Then run and drain the fuselage tank next, followed by the right wing tank. You can check if any fuel was fed into the left or the fuselage tank by checking the gauges, and setting the fuel tank selector to either the left for auxillary tanks. You'll notice that no fuel will feed, the tanks are still empty. This is what's included in my track replay, linked above. 2) THE INFORMATION The fuel vapor return passes excess fuel from the carbureator back to a fuel tank. It is widely touted that this excess fuel was routed back to the left wing tank. However, starting halfway through P-51D-15 production, this line was redirected to instead feed into the fuselage tank behind the pilot, using the same opening as the fuselage tank vent line. Photos: The following two photos were taken from the Pilot Training Manual, AAF Manual 51-127-5, dated 15 August 1945, from page 20 and 22 respectively: Now here we have a maintenance manual (AN 01-60JE-2, 13-Feb-1948 Section IV, Para 14-15) stating the same thing, with some more detail. In addition, a representative drawing showing the placement and path of the fuel lines: Now, how is this dated to the P-51D-15? If you look at the schematics for the Mustang, you'll see assemblies for building the pipes to link the carbureator to the fuselage tank. Here you'll see this fuel vapor return line, returning fuel to the fuselage cell vent. On the bottom left, it reads used on P-51D Airplanes AAF 44-15253 & Subs[equent] also on AAF 44-11953 and Subs[equent]. The P-51D serial number is a D-15 airplane, halfway through their production run. So it's clear that when referring to the Californian Mustangs, it's specifically pointing out the middle of the P-51D-15 variants, when the vapor line change was implemented. However in this source, it seems that some Dallas-built Mustangs serial numbers are excluded or missed. I think we can assume though that the change occured similarly as in Cali, on the D-15s. 3) THE FIX At a rate at 10 gallons per hour or less, fuel should be fed back into the fuselage tank. For simplicity sake, it could be a generalized 7 gallons per hour, as DCS pilots will constantly change their engine settings between economic settings and military power, or even WEP. THE FUSELAGE TANK VENT LINE: 1) THE ISSUE In DCS, this fuel vent line is not in the 3D model at all 2) THE INFORMATION This was a tube that vented the fuselage tank, and gave air a place to enter the tank to stabilize the pressure as fuel was consumed. Additionally, with the fuel vapor return tube directly connected to it at the point that the joint where the vent tube met the tank, this would be the pathway that excess fuel would be leaked overboard and outside the aircraft, in the event the fuselage tank is full. Schematic drawings: Exerpts from the E&M Manual: 3) THE FIX The vent line isn't even represented visually in the cockpit, but it's in a very hard to see location so it's not that pressing. However, it is also not even seen from the outside, specifically the outlet port, that was located at the bottom of the USAAF insignia on the right side. It is an external identifying mark of Mustangs with the fuselage tank installed. And in addition, it is also where fuel will vent outside the aircraft, in the event the fuselage tank is already full, and getting fed by the fuel return line from the carburator.

Hello let me know if a track is needed. The low fuel warning lights in Mi-24 both turn on simultaneously at 240 L left, or 120 L left in tank 1 and same amount in tank 2. However currently it seems to turn on around 200 L. It seems this might be Becuase of the unusable fuel capacity of 40 L being useable in DCS, which I believe happens with some other modules. It might be easier to see this happen with the fuel tank Selector in the 1 or 2 position rather then total, as the tank 1/2 scale on the gauge is easier to see small changes with. I do not mind being able to use unusable fuel of 40 L, but I wanted to post this just in case it was desired to have the low fuel warning light actually appear at 240 L indicated. Currently there is no problems compared to real life procedure with the exception of the fuel tank gauge being about 40 L lower then actual fuel level. I think it would be nice if either fuel tank warning happened at 240 L indicated (even though that would give you slightly more time until empty then stated in manual), or if the fuel warning was moved to 240 L as it is suppossed to be and the un-useable fuel capacity of 40 L eliminated Just wanted to bring this up. If track is needed or video I can do so right away

I just did some fuel consumption tests over 20nm at about 100kn, results are as follows: At max throttle it consumed a bit under 300 pounds. At idle throttle it consumed a little over 200 pounds. Worth noting is that I did not refuel in between tests but I doubt it would lead to a considerable difference. Would love to know how this holds up to real world data.

Hi everyone, I've noticed that the maximum amount of fuel available for the S-3B tanker is the same as for the S-3B (non-tanker), at 12125 lbs (5500 kg). This is despite the fact that the S-3B tanker in DCS, is always configured with a 300 US-gal drop tank (and of course the air refuelling store (Sargent-Fletcher A/A42R-1)). The drop tank should obviously add 300 US-gallons of fuel and the buddy store itself also contains at least 300 US-gal of fuel (and the fuelling and dump port are present on the model). Right now, only the internal fuel of the S-3B is accounted for in the tanker unit. They say a picture speaks a thousand words, so here's 3. Here's an image of the S-3B rearming window, showing a maximum of 12125 lbs of fuel: Here's the same S-3B, but fitted with 2 300 US-gal drop tanks, note that the maximum amount of fuel has increased to 16155 lbs: And finally, here's the S-3B tanker, which can be seen with a 300 US-gal drop tank and the A/A42R-1 air refuelling store, as you can see the maximum amount of fuel is 12155 lbs (as in the case with the S-3B with no drop tanks fitted): Here's a source, approved for public release, stating that the D-704 pod has 300 US gallons of internal capacity (see page 2/page 8 of the pdf reader). EDIT: As an addendum (thanks silverdevil) you can also see that the total mass of the aircraft for an S-3B with just internal fuel, is identical to that of the tanker - meaning that not only are the drop tank and air refuelling store empty of fuel, but are also massless.