A few basic questions about mid-air refueling

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some things that sound basic 1. how many times can an aircraft be refueled in mid-air. I've always assumed it was as much as it needs 2. usually around what % of remaining fuel min, is refueling optimized for? and does mid-air refueling, refuel's the plane at 100% fuel capacity?
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1. The limits to endurance afforded by repeated aerial refueling is caused by aircrew efficiency/fatigue or low engine oil levels due to consumption (for UAVs). B-2s flying from Whiteman AFB to the Middle East or Southwest Asia refuel a dozen times or more, but the aircrew is whipped by the time they land. 2. The point at which an airplane needs to refuel is based on having enough fuel to fly to a divert airfield in case the aerial refueling system breaks (either on the receiving airplane or on the tanker). The tanker can provide as much fuel as the receiving airplane needs, up to 100% capacity. But the receiving airplane's crew needs to make sure they don't take too much fuel on the final leg of their sortie or they could be overweight for landing.
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some things that sound basic 1. how many times can an aircraft be refueled in mid-air. I've always assumed it was as much as it needs 2. usually around what % of remaining fuel min, is refueling optimized for? and does mid-air refueling, refuel's the plane at 100% fuel capacity?
Well first off there is something called Pre-flight planning.. That means the pilots has done all or above 90% of all the mission flight plan down to details. It means the pilot of say an Su-34 or B-1 or whatever has pre-calculated how much fuel they need, well there are variables when it comes to fuel consumption, but still. The pilots know pretty much how many times they need Inflight refueling. But again, there is a big difference in the different missions. If the mission involve some F-35 or other fighters going across Atlantic, then the tanker stays with them all the way. And since they are over water most of the leg, they refuel very often. They seldom get below 70% full tank. This has to do with the lack of nearby Airbases. But if the mission include a Su-34 flying Voronezh - Far-east on an strike exercise. It only require 3 mid-air refueling, and then it might involve two different tankers, because of the long time between each tanker support. Besides, the Su-34 has many aviable airbases that it can land on along the route, so it can tank up when it reach like 30-40% of full tank. I don't think they would go any less under 40% of full fuel. It has something to do with flight plan and safety regulation. If we take the F-15C in DS. then they call in the tanker support when they need them. Real time combat mission is highly dynamic. So there will allways be one or more tankers on 24/7 standby, imo in the air.
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In 1967 two HH-3Es of the United States Air Force made the first nonstop flight across the Atlantic Ocean by helicopter. Departing from New York in the early hours, the two helicopters arrived at the 1967 Paris Air Show at Le Bourget after a 30 hr 46 min flight.[6][7] The operation needed nine in-flight refuelings.
Talking about planning! Reading the last post I was wondering how many tankers were involved in this flight. A KC-130 can't be in the air for that long without refueling and staying with the helos with their much different speed is also difficult.

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Don't forget the situation faced by the Royal Navy's Fleet Air Arm during the 60's - where IFR was used to enable Buccaneer S.1's to take off from a carrier with a full weapons load - but light on fuel. Once airborne, they were 'topped up' by Scimitars in a budy-buddy system to enable them to reach their full range. So this was a case of IFR being used to enable full-weight takeoffs. Just my six penn'orth Ken

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I think Y-20 has a legitimate point : Which is an optimal fuel cycle for long range missions? The less you have the less you drag, on the other hand there are problems underlined above, time lost for refueling, security margins etc.

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Don't forget the situation faced by the Royal Navy's Fleet Air Arm during the 60's - where IFR was used to enable Buccaneer S.1's to take off from a carrier with a full weapons load - but light on fuel. Once airborne, they were 'topped up' by Scimitars in a budy-buddy system to enable them to reach their full range. So this was a case of IFR being used to enable full-weight takeoffs. Just my six penn'orth Ken
F-105s flying from Thailand to bomb North Vietnam did the same thing.

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Your US Navy bubbas build a 'fuel ladder' based on expected recovery time. During cyclic carrier operations, the deck is open for launches (all four Cats stroking), then it's open for recoveries (keeping the landing area clear and allowing recovering jets to stage on the bow). The fuel ladder is marked in 15 minute increments in order to reach (ideally) max trap weight at the planned recovery time (usually recovery +15 min). Let's say you've got a 1400 launch and a 1530 recovery. Expected fuel for a 36K FA-18 (Max Trap) might range from 4.5K to 6.0K (thousand pounds). You'd look at your weight sheet in MX prior to launch and calculate the max trap fuel weight for the ordnance being carried (we'll say it's 4.5K remaining). Starting at 1545 (15 min after recovery starts) I'd want to be at 4.5K. From there, add 1.2K every 15 minutes (fuel burn at normal low altitude loiter) until you reached your launch time. 1530: 5.7K 1515: 6.9K 1500: 8.1K 1445: 9.3K 1430: 10.5K 1415: 11.7K 1400: 12.9K This means I'd need to have 12.9K of fuel at launch in order to be 'On Ladder'. Some platforms if heavily loaded burn a lot more every 15 minutes and often, you'd bump up the amount burned when heavier for more realistic numbers. Keep in mind that this isn't a tactical airspeed. It's driving around at Max Range until you get over the ship and then switching to Max E. Anything you've got 'above ladder', means fuel to play with or employ with. Back to the OP, tanking fragged give would typically be 2-3K for each receiver from CVN based organic tanking. You could rarely take more if you were fragged for 'frontside give' regardless...simply can't burn that much right after launch getting on the tanker. Backside frag is a different story but then again, the savvy Naval Aviator would never depend on backside give if he could help it because it could disappear for a myriad of reasons. Big wings could be fragged for more but it depends on how many receivers they've got.

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Sometimes, the problem isn't the receiver, its the number of tankers available. I recall one situation over the southern Indian Ocean flying from Perth when we had two KC-135As to refuel a single WC-135B weather aircraft on a long distance mission to do atmospheric research. We couldn't do the entire mission because the tankers had to retain so much fuel that when we got all the way to the second A/R, they could only offload a small fraction of their fuel load because it as a loooong way back to Perth! A couple of people questioned that but after showing them that most maps of the world made in the U.S. go north to the pole, but only show the southern hemisphere to 60 degrees S they got the "picture". There's a lot of additional water down there! One other situation: in 1976 we (the USAF/SAC) decided to celebrate the 200th anniversary of the US by flying an SR-71 around the world to set a new speed record for a non-stop around-the-world flight. It would have cut the existing record (set by a B-52 I think) in half or more I think. In the process of planning the flight, we discovered there were not enough tankers (KC-135Qs capable of refueling the SR) in the USAF inventory for the attempt. When you added the primary tanker, the air-spare (in case the primary aborted or broke), and in some cases a ground spare (to replace a broken air spare) the 50 or so Q-model tankers in the inventory (some were always down for routine/depot maintenance) weren't enough. A few years later when the KC-10 was also available we might have made it, assuming MAC would have lent SAC about a dozen or two KC-10s. The bottom line: each situation requires careful planning and depends on what you are doing and where you are going. The basic planning rule is never let the receiver (or receivers) get below the onboard fuel necessary to get to an emergency divert base.
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Limitations on the number of times in-flight refuelling can be accomplished often involved crew complement of the receiver aircraft more than the aircraft itself. It can be a very challenging task, and very fatiguing especially towards the end of a particularly long flight. It can be a very perishable skill for many although for others it's just like riding a bike again. Secondly, as Dragonflyer noted, tanker availability is often an issue. The number of aircraft that require AAR can often exceed the tankers available.
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Limitations on the number of times in-flight refuelling can be accomplished often involved crew complement of the receiver aircraft more than the aircraft itself. It can be a very challenging task, and very fatiguing especially towards the end of a particularly long flight. It can be a very perishable skill for many although for others it's just like riding a bike again. Secondly, as Dragonflyer noted, tanker availability is often an issue. The number of aircraft that require AAR can often exceed the tankers available.
hey guy, this thread might be interest to you http://forum.keypublishing.com/showthread.php?141500-Trainer-aircraft-progression-What-is-ideal

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F-105s flying from Thailand to bomb North Vietnam did the same thing.
...and SR-71s on virtually every mission they flew.