I am sure that this has been hashed over many times before, and I thought I had it down pat, but ...

 

I would like to get some information about refueling.

 

1) I am currently working my way through West Pac 7, Thanh Hoa Bridge, using the demo of HCE. I have never had a problem with refueling before (which isn't saying much, though). But in this scenario, I am having problems. It was my understanding that you bring the tanker group and the group to be refueled close together, loiter both at the same altitude, and then join the groups. After 60 s, the refueling starts automatically.

 

I used this procedure several times with a "test" scenario and at various points in the main game, using various combinations, and over several game sessions. Only twice did the automatic refueling work (with the S-3B and an Intruder). All the other times, I had to resort to ALT-r.

 

Now I don't have a problem with giving the planes explicit instructions to refuel.

 

What I don't understand is why what appears to be the identical procedure for making something happen (the automatic refueling) does not produce identical results for each attempt. Surely computers are just big adding machines that obey the commands of their human masters? Is there an additional condition that I am not aware of? Is there a random aspect to the procedure?

 

2) I understand that a tanker can only refuel planes once. But how much fuel does the tanker carry i.e. how much fuel is transferred? And what happens when the group to be refueled contains multiple planes, possibly of various types?

I used this procedure several times with a "test" scenario and at various points in the main game, using various combinations, and over several game sessions. Only twice did the automatic refueling work (with the S-3B and an Intruder). All the other times, I had to resort to ALT-r.

 

Are you sure that all the aircraft in your group(s) were actually capable of in-flight refueling? Some are not. You can only check for this in the database using the Platform Editor.

 

I understand that a tanker can only refuel planes once. But how much fuel does the tanker carry i.e. how much fuel is transferred? And what happens when the group to be refueled contains multiple planes, possibly of various types?

 

Tankers offload a quantity of fuel equal to the range of the tanker's own loadout. Take a KC-10 Extender tanker, for example:

 

Its tanker loadout has a range of 7,500 nm.

 

Suppose you join that KC-10 to a group of B-1 bombers (say four of them).

 

The KC-10 can give each B-1 bomber 1,875 nm worth of fuel (7500/4).

 

You will have difficulties if you try to refuel groups of aircraft of mixed types.

Are you sure that all the aircraft in your group(s) were actually capable of in-flight refueling? Some are not. You can only check for this in the database using the Platform Editor.

 

In 1957, SAC's fighter units transferred to Tactical Air Command or were inactivated as part of a reorganization of Air Force strategic and tactical assets. However, they set the standard; by the end of the 1950s, trans-oceanic flights became commonplace. The Air Force never bought another fighter aircraft without in-flight refueling capability; a capability which proved its worth a few years later when Vietnam heated up.

 

(from http://www.amc.af.mil/news/story.asp?id=123144488)

 

The US Navy frequently used carrier-based aerial tankers like the KA-3 Skywarrior to refuel Navy and Marine aircraft such as the F-4, A-4 Skyhawk, A-6 Intruder, and A-7 Corsair II. This was particularly useful when a pilot returning from an airstrike was having difficulty landing and was running low on jet fuel. This gave him fuel for more attempts at landing for a successful "trap" on an aircraft carrier. The KA-3 could also refuel fighters on extended Combat Air Patrol.USMC jets based in South Vietnam and Thailand also used USMC KC-130 Hercules transports for air-to-air refueling on missions.

 

(from http://dic.academic.ru/dic.nsf/enwiki/149765)

 

Phantoms, Intruders, Corsairs; Viking tankers; that's the OB in the scenario.

 

And then, of course, there's "Flight of the Intruder" which describes tanker operations, using Intruder tankers.

 

So I think that all my planes SHOULD be capable of in-flight refueling, but it may be possible that a flag has been incorrectly set?

 

Tankers offload a quantity of fuel equal to the range of the tanker's own loadout. Take a KC-10 Extender tanker, for example:

 

Its tanker loadout has a range of 7,500 nm.

 

Suppose you join that KC-10 to a group of B-1 bombers (say four of them).

 

The KC-10 can give each B-1 bomber 1,875 nm worth of fuel (7500/4).

 

You will have difficulties if you try to refuel groups of aircraft of mixed types.

 

thanks

So I think that all my planes SHOULD be capable of in-flight refueling, but it may be possible that a flag has been incorrectly set?

 

Okay, history lesson aside, the E-2B Hawkeye which appears in the scenario is NOT IFR capable, nor should it be.

 

The RA-5C Vigilante, which also appears, should be and is missing its flag. (This will be fixed in the next iteration of the HCDB).

 

(I always aim to try and make sure whatever help that's posted here will be useful to anyone who might read it. It helps to cut down on the same questions being asked repeatedly (in theory, at least) and to eliminate the variable between the chair and the computer. So, whenever someone posts a tanker/refueling issue, it is useful to determine early on if the aircraft involved are actually IFR capable).

[

Tankers offload a quantity of fuel equal to the range of the tanker's own loadout. Take a KC-10 Extender tanker, for example:

 

Its tanker loadout has a range of 7,500 nm.

 

Suppose you join that KC-10 to a group of B-1 bombers (say four of them).

 

The KC-10 can give each B-1 bomber 1,875 nm worth of fuel (7500/4).

 

You will have difficulties if you try to refuel groups of aircraft of mixed types.

 

That means that I can fly a tanker out to its max range and it will still give it's loadout?

 

BTW, does the AI refuel in flight?

That means that I can fly a tanker out to its max range and it will still give it's loadout?

 

Yes. I may be wrong, but I think you can receive the same fuel load as long as the tanker is available to give it. (Confirmed with Tony).

 

BTW, does the AI refuel in flight?

 

Only if you (as the scenario author) include a tanker with the AI group of aircraft that is scripted to be launched. Individual aircraft or groups of AI controlled aircraft are not smart enough to seek out and join with a tanker for refueling.

Some more detailed information.

 

The tanker I am using is the S-3A Viking. As a tanker, its range is 2600 nm.

 

Attempting to refuel:

 

a) RA-5C : refueling proceeds normally, except that the RA-5C never actually GETS the fuel (it is simply dumped into deep space!). ALT-r gives the same result.

 

E-2B : refuels only with ALT-r, but the fuel is dumped. [1]

 

c) F-4B : refuels only with ALT-r.

 

d) A-6A : refueling proceeds normally. [2]

 

e) A-6B : refuels only with ALT-r. [2]

 

f) A-7E : refuels only with ALT-r. [2]

 

So a) is incorrect, and that will be fixed by setting the refueling flag on the RA-5C. is correct. d) is correct. c), e), f) are workable by manually giving the refueling order. Is this also a case of a missing flag?

 

 

Notes:

 

[1] I never actually attempted to refuel the Hawkeye until I started running the tests. The Hawkeye has quite a long range and a very slow speed. This translates into a very long loiter time. I first noticed the "bug" when I tried to refuel a Phantom that hadn't yet expended its missiles. The Phantom tends to have the shortest loiter time in this scenario.

 

[2] As I was working through the cases, I started to collect some additional information and got some very odd results. All my fighters and attack planes are operating in groups of 2. Thus they should be getting 1300 nm of range per plane. The A-7E went from 84% to 89% bingo (approx 1400 nm to 1950 nm). The A-6B went from 82% to 83% bingo (1550 to 1600 nm). The A-6A went from 11% to 88% bingo (435 to 2100 nm). The A-6A normal maximum range for the particular mission is only 1700 nm.

 

One possible explanation is that the amount of fuel received is added not to the current amount of fuel, but to the bingo amount. This may only apply for manually forced refueling. I would expect that the fuel received would be added to actual fuel in the tanks, especially during normal refueling. But the fuel given should not exceed the volume of the tanks.

 

One possible explanation for the "bug" is that a plane needs to have less than a certain amount of fuel in order to refuel normally, but I noticed the problem when I tried to refuel a Phantom that was definitely short of fuel, after which I started looking at the other planes.

 

[3] b followed by right parenthesis produces a smiley.

No other aircraft appear to be missing their IFR capable flags (or have flags when they shouldn't).

I am thinking that there must be an additional requirement beyond what I have been considering for the normal refueling to work. I expect that the refueling check uses a robust algorithm i.e. if it ever works as intended, then it always works as intended, and all those instances where it doesn't appear to work are because some human eg. myself has done it wrong.

 

The "refuel check" algorithm would be executed every time you join 2 aircraft groups.

 

My current working hypothesis is that the extra condition is the one highlighted in red in the flowchart below. "Aircraft needs fuel" would most likely mean "aircraft does not have enough fuel to reach any friendly base". Otherwise, why transfer fuel? Of course, there are reasons, but for all those, you ought to give a special refuel order (ALT-r).

 

While I think that this is a reasonable guess, it would be nice if a programmer (or progamer) who actually knows could confirm or deny it.

____________________________________________________________

 

See post 15, this thread, for the correct procedure.

I ran some trials, and I believe that I now have the answer to my own question.

 

In WestPac 7 (using the demo of HCE), I launched 4 pairs of planes, one each of Phantoms, Corsairs, A-6As, and A-6Bs. Each of these groups was followed by a single Viking tanker. At about 100 nm out, all 8 groups loitered at low. The tankers were within about 5 nm of the refuelees.

 

I saved the game at this point.

 

In test 1, I grouped each of the first 4 pairs of planes with its accompanying tanker. Nothing happened. All planes had lots of fuel at this point.

 

In test 2, I forced refueling (ALT-r) with each of the 4 combined groups. Fuel was transferred in each case.

 

Then I reloaded the save game.

 

Then I waited for the fuel to get used up, speeding up the game as necessary.

 

As each group started blinking, I joined it with its accompanying tanker. In each case, I waited until the refuelees were at 0% bingo. (Just as an aside, the Phantoms run out first, then the Corsairs, then the A-6Bs, then the A-6As.) 0% bingo means that the planes still had 100-200 nm of range more than the distance to the carrier.

 

In all 4 cases, fuel was transferred automatically.

 

While this is not as good an answer as reading the algorithm, I think that it confirms the hypothesis that a plane must actually "need" fuel before the automatic refueling process kicks in, i.e. the flowchart in post 9, this thread, is correct, including the "need fuel ?" check. However, "needing fuel" happens when the plane still has a substantial fuel reserve.

 

I believe that any discrepancies between this result and previous statements I made in this thread are because the previous measurements were not done carefully enough.

 

I also collected data on the amount of fuel transferred. There are errors in the transfer amounts, but that will not be dealt with here.

This tallies with what I have seen so far.

 

In the "Backyard" scenario I was able to stage a mission from Guam to Burevestnik by 12 F-111D and one EF-111A supported by 3 patrols of KC-10s (3 aircraft each), but was unable to replicate the same mission if the 6 tankers were launched in the same group as the Ardvaarks. It would seem that as soon as the "need fuel" flag lights up, the plane refuels so the fuel transferred may not be enough to complete the mission and there would remain unstransferred fuel in the tanker.

This tallies with what I have seen so far.

 

In the "Backyard" scenario I was able to stage a mission from Guam to Burevestnik by 12 F-111D and one EF-111A supported by 3 patrols of KC-10s (3 aircraft each), but was unable to replicate the same mission if the 6 tankers were launched in the same group as the Ardvaarks. It would seem that as soon as the "need fuel" flag lights up, the plane refuels so the fuel transferred may not be enough to complete the mission and there would remain unstransferred fuel in the tanker.

 

This would mean that loitering was not a precondition for fuel transfer (although that would help 2 groups to join), and perhaps the altitude requirement as well.

 

It would also appear to indicate that the refueling check was not initiated at the time of grouping, but rather as soon as the plane was "low" on fuel.

afaik there is no loiter requirement (in fact the planes have to be at Cruise to refuel) and no altitude requirement either. Correct as well that there is zero correlation between joining time and the start of refueling, the refueling is entirely dependent upon fuel state.

 

What I need in order to troubleshoot is a small test scen (ideally a Red sub, and on the blue side as few units as possible to recreate the refueling inconsistencies). Then run the scen until the moment just before refueling starts, save the game. Repeat as needed for the various different strangenesses. Then zip up the scen and saved games and put them into a new issue report here at HG.

afaik there is no loiter requirement (in fact the planes have to be at Cruise to refuel) ...

 

Definitely no loiter requirement. I have joined 'tanker to recipient' groups on the fly many times. You get the prompt for Cruise speed afterward.

afaik there is no loiter requirement (in fact the planes have to be at Cruise to refuel) and no altitude requirement either. Correct as well that there is zero correlation between joining time and the start of refueling, the refueling is entirely dependent upon fuel state.

 

Definitely no loiter requirement. I have joined 'tanker to recipient' groups on the fly many times. You get the prompt for Cruise speed afterward.

 

Interesting information. Today my previous "understanding" of the refueling procedure has been completely undone.

 

I just ran another test. WestPac 7, 1 Phantom, 1 Viking. The Viking was cruising along at medium. The Phantom was zooming around at top speed to use up fuel. Once the Phantom was at 0% bingo, it cruised toward the Viking at low from the opposite direction. When they were close enough, I grouped the two planes, and both planes assumed the same course and speed (slowest cruise of the 2 planes). 60 s later (the usual refueling delay), I was prompted to set the planes to "cruise", although they were both at cruising at the time. I said OK. There was no change in the speed, but the Viking was forced to low. 30 s after that, the refueling was complete.

 

So it would appear to be the case that automatic refueling has the following requirements:

 

1) A plane needs to be "low" on fuel (at least blinking).

2) Then a search is done (continuously i.e. every 30 s) for an available tanker in that group.

3) If found, then the computer takes care of altitude and speed issues. Cruise or loiter works.

 

This procedure should be included in the manual.

 

For certain long-range missions, especially involving multiple refueling, it will be necessary to ensure that the tankers are in individual groups, because you will probably want to run the tanks dry before manually requesting more fuel, and the automatic procedure doesn't do that.

 

I have deleted my incorrect flowchart in post 9, this thread.