The Future Of Aerial Refueling Includes Stabilized Drogues And No Humans

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Aerial tankers can fuel up hungry jets, turboprops and even helicopters equipped with a refueling probe by trailing a hose and drogue behind them. In smooth air, such a mating dance can be a challenge, in rough air and bad visibility it can become downright scary. A new ‘smart drogue’ system in development may finally help make ‘plugging in’ a less terrifying affair.

The ‘hose and drogue’ method of aerial refueling is far more common around the globe than the USAF’s ‘big tanker’ boom and receptacle method. The advantage to the boom and receptacle method is that it is faster and more reliable, especially under harsh conditions, and the rigid boom can pump fuel into the receiver aircraft at much higher rates than a flexible hose can. Still, this system requires large and complex dedicated tanker aircraft, and interoperability during international operations can be an issue. Meanwhile, tactical hose and drogue refueling capability can be acquired cheaply via purchasing ‘buddy refueling pods’ for existing fighter aircraft and it can even be procured on a strategic level at a low cost from ‘pay by the hour and pound’ commercial aerial tanker providers.

During hose and drogue tanking operations, a deployed drogue, or ‘basket,’ can hop around in turbulence and it can even be effected by the slipstream and ‘bow wave’ of the connecting aircraft. Additionally, minor asymmetry or damage to the basket can make it wobble about and oscillate rapidly, making plugging into it nearly impossible.

Even in good conditions, extreme pilot concentration is needed to couple with the basket, which can be a taxing affair after a long combat mission or while flying through stormy weather after repeatedly trying to land on an aircraft carrier at night.

Just like how munitions have become independently guided over the last half century, now the aerial refueling drogue may be getting an intelligent upgrade of its own in the not so distant future. The idea is to create a smart, stabilized drogue that can attach to modern hose and drogue style refueling systems. This smart drogue has sensors onboard that constantly assess the basket’s movement, and small winged surfaces behind the basket rapidly adapt to any errant motion. The result of which is something of an active buffer, that can greatly reduce the movement of the drogue even during intense turbulence and shearing airflow.

 

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In a way, similar ‘active’ dampening systems are designed into ships to minimize the effects of wave motion on the vessel. Some aircraft, such as the B-1B Bone, have small canards vanes that do the same thing during low-level, high-speed interdiction missions. Even our cars have stability assist traction systems that buffer sliding and loss of traction via the use of the car’s ABS system. Adapting a similar active stability system to aerial refueling seems like a no-brainer and, if anything, it is probably quite overdue considering the money and stakes involved with the act of aerial refueling to begin with.

As a whole, hose and drogue refueling technology has began to become more user friendly over the last couple of decades. Another area where this is happening is in variable speed baskets that can refuel a wider range of receivers.

In the past, different baskets had to be fitted based on what speed the receivers operate at. This means that a KC-130 tanker could not refuel fighters and a loaded down MH-53s in the same mission. This is now changing with companies likeCobham making variable speed baskets. Currently, this is what the company has available when it comes to refueling baskets:

- Low speed VDD: 100-180 kts (Compatible with helicopter and tilt rotor probes)

- High Speed VDD: 180-325 kts (Compatible with NATO STANAG 3447 compliant probes)

- Variable Speed VDD: 105-215kts (Developed for the 48-000 pod on USAF C-130 Aircraft)

Cobham is now working on an all-speed basket that can refuel the whole range of combat aircraft without being changed. Such a system, fitted with the Actively Stabilized Refueling System, would make life much easier for both tanker crews and receivers and will allow for less tankers being needed to support more disparate aircraft on a single mission. It will also allow for faster, more reliable tanking, which in itself allows for more fuel being available for receivers on a single tanker mission.

Emerging unmanned combat air vehicles, like the Navy’s X-47B and the UCLASS production aircraft that will follow it, have a great advantage in range over similar sized manned systems. Just because they can fly farther does not mean more range would not be beneficial, in fact it would only multiply their usefulness. Thus, aerial refueling of these unmanned systems is a very relevant capability to have. By providing a stabilized drogue system, that is more resistant to turbulence and airflow variations and thus basket movement, unmanned subsystems used for autonomous refueling will be more reliable and may even exceed the capabilities of manned aircraft as their abilities evolve.

read more at
http://foxtrotalpha.jalopnik.com/the-future-of-aerial-refueling-includes-stabilized-drog-1673992575

Over the last decade, NASA, in conjunction with the DARPA, have tested autonomous aerial refueling with both their F/A-18B Hornets and with RQ-4A Global Hawks. The Hornets, loaded with the same sub-systems that can be installed on unmanned aircraft, plugged into the basket multiple times, and incredibly smoothly at that, without the pilot’s hands touching the controls. The Global Hawks flew in perfectly tight formation, just short of making contact between the basket and the probe, to demonstrate that even high-altitude aerial refueling is possible with an aircraft as fragile and that operates in such a tough aerodynamic environment as the Global Hawk.

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Calspan’s unmanned aircraft surrogates (Learjet 25s) are leading the realm when it comes to tactical unmanned aircraft aerial refueling capabilities. Using Precision Relative GPS and a similar data-link architecture as what allows the Navy’sexperimental X-47B Unmanned Combat Air Vehicle (UCAV) to land on an aircraft carrier, Calspan’s Lear acts just as an X-47B would while approaching the tanker and suckling its basket for gas. During tests in 2013, the Calspan Learjet 25 fitted with a refueling probe and with X-47B’s avionics, autonomously connected with a KC-707 tanker as if it were refueling operationally.

The work that Calspan is performing was supposed to lead directly to live testing with the X-47B as part of the drone’s overall program goals, but the objective was cut in 2013 due to budgetary restrictions. Today, the X-47Bs continue to serve in flight testing, although it is not clear if the Autonomous Airborne Refueling Demonstration will ever take place under the program. Still, in many regards, this technology is fairly proven and somewhat mature, and it will only get easier to apply operationally if an Active Stabilized Drogue System were fitted to the tanker’s basket.

Update 4/22/15: X-47B has autonomously refueled from a KC-707

All these hose and drogue tanker developments are a good thing, as they undoubtedly will result in aerial refueling capability for operational unmanned systems and easier refueling for manned systems in the future. In fact, some say that the USAF has been providing aerial refueling for shadowy unmanned aircraft with its boom and receptacle method for sometime, with the capability presumably being proven in the black-budget world long ago.

The truth of the matter is that the tankers of the future, not just the receivers, will most likely be unmanned. On a tactical level an Unmanned Combat Air Vehicles (UCAV) will be very well suited for being a Carrier Air Wing’s tanker aircraft, as they possess a superior range to begin with than manned fighters, such as the Super Hornet or F-35C. With its internal weapons bays filled with gas tanks and two more tanks carried on its wings, stealthy carrier borne UCAVs that may have struck targets deep inside enemy territory one day will be able to act as an escort, launch or recovery tanker the next.

On a larger scale, one day we may see aircraft as big as the upcoming KC-46 Pegasus tanker become optionally manned, or totally unmanned, to refuel their unmanned UCAV and even bomber brethren autonomously. Presumably, such a unmanned tanker would be able to do so with remarkable efficiency, as it would be networked with the rest of its unmanned swarm, which will work to make all their collective movements and actions as efficient as possible in an effort to complete their common objectives with the highest chance of success.


http://foxtrotalpha.jalopnik.com/the-future-of-aerial-refueling-includes-stabilized-drog-1673992575

Although a fully unmanned vision of air combat and aerial refueling may still be some time out into the future, in the mean time, an aerial refueling basket that moves less when a receiver is trying to plug into it would be a godsend for combat aviators around the globe and it would save money through efficiency. The idea of a stabilized drogue, maybe one that can accommodate a vast array of aircraft operating at a wide range of speeds, also begins to take away some of the luster of the more expensive but efficient boom and receptacle aerial refueling method. In the end, these new technologies—stabilized drogues, all-speed baskets and unmanned refueling—will help unlock a new user friendly era of air combat, even if that user ends up being a a flying computer networked to dozens, or even hundreds, of other flying computers.

 

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smt

 

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tornado

f18

 

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Refueling in Flight: Past and Present
On the invention of flying tankers

Aerial refueling is not only one of the most complex elements of flying, but also an audience favorite during airshows. Unfortunately, pilots do not demonstrate this process as often as we would like, as the process is both complicated and dangerous, given that the two aircraft must come within 20 meters of each other. The history of the idea of in-flight refueling is just as fascinating.

It is believed that the idea of in-flight refueling was first developed in Russia in 1917 before being patented in 1921 in the USA by the Russian émigré, test pilot, and aircraft designer Alexander Prokofiev-Seversky.

Alexander Nikolaevich Prokofiev-Seversky, a Russian and American pilot, inventor, and aircraft designer (1894-1974)


The first attempts at refueling during flight took place in 1912 and looked quite funny, with a can of gasoline passed from one airplane to another. The idea of dropping a hose from one plane and catching manually to another was subsequently developed. Of course pumps had not yet been developed at this point, so fuel transferred from one aircraft to another through gravity.

The first successful refueling using this method took place on June 27, 1923, by pilots of the United States Air Force. The wing-to-wing refueling took place between two Airco DH.4 aircraft.

The first in-flight refueling of the Airco DH.4 aircraft on June 27, 1923


A new era for competing for the longest flight duration without landing had begun. Beginning in 1923 with a 37-hour flight that required refueling in air nine times, by the mid-1930s, American pilots had learned to stay in the air for several weeks.

In 1935, brothers Fred and Al Key set a new record for a non-stop flight in the airplane Curtiss Robin, staying in the air for 653 hours and 34 minutes (more than 27 days). They took off on June 4 and landed on July 1. Food was lowered down to the pilots. Maintenance on the engine also was carried out in flight, for which a special platform was built around the motor so that one of the pilots could work there when necessary.
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In-flight refueling of the aircraft Curtiss Robin


At the time, the method of refueling with a hose attached to a conventional fuel nozzle was extremely dangerous. At any moment, the nozzle could come out of the mouth of the fuel tank, sending jet fuel straight into the hot motor housing.

This process is not much easier now. Naturally, only military aircraft are built with in-flight refueling capabilities. Passenger planes will likely never rely on in-flight fueling, not only because of safety concerns, but also because of a lack of necessity, as passenger flights are rarely so long or secretive as their military counterparts.

Returning to the 1930s, in Great Britain the famous English pilot Alan John Cobham in 1934 developed the world’s first real in-flight refueling system, consisting of a rope with claw hooks, harpoons, and a hose. To improve this system and the production of related equipment, Cobham founded the company Flight Refuelling Limited (FRL), which still exists to this day.

The idea of tanker planes began to develop in Russia at the beginning of the 1930s under the initiative of the famous aircraft designer Vladimir Sergeyevich Vakhmistrov. He carried out the first successful tests in 1932.

Until the beginning of the Cold War, though, the development of refueling methods remained primarily the business of individual enthusiasts, who focused not on military application, but rather on transatlantic commercial flights.

In-flight refueling of the MiG-19 (SM-10)


The advent of nuclear weapons forced governments around the world, particularly the Soviet Union and the United States, to think about ways to increase the radius of their strategic and tactical aircraft operations. Research into in-flight refueling methods received official status.

In the Soviet Union, work was conducted on various sizes of aircraft. Vakhmistrov, who had successfully reversed engineered the ideas of the British company FRL, participated in this process.

Test pilots Igor Shelest and Victor Vasyatin developed their own wing-to-wing system of in-air refueling. Their invention was also based on the FRL method but was much more effective and simple. This system was subsequently adopted by the Soviet Air Force and used through the late-1990s.

The wing-to-wing system was only in the USSR, and then only with the Tu-4 and Tu-16 airplanes. No other country utilized this method, believing it to be too risky.

In-air refueling of the Tu-16R


Throughout the rest of the world, the hose-cone-rod system was much more popular. This system was developed in late 1952 by OKB-918, known today as the famous Zvezda Research and Production Enterprise named for G. I. Severin, which is part of the holding company Aircraft Equipment.

Vladimir Vakhmistrov and his group, continuing their work at OKB-918, developed the basis for the the hose-cone-rod system, which in 1953 was successfully tested by refueling two MiG-15 aircraft from a Tu-4 tanker without the use of cables. Two refueling points were located on the wingtips, and manufactured hoses with cones docked with the refueling points using special telescoping arms that fixed to the sides of the fighter jets.

 

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In the mid-1950s, when the issue of in-flight refueling for fighter jets had lost its relevance, this system was adapted for bombers, particularly the strategic M-4 aircraft. From that point, the smaller Tu-16 was used as a tanker aircraft.

In-air refueling of the Su-24


With the introduction of the new frontline Sukhoi Su-24 (1975) bomber into the Soviet Union’s Air Force, scientists began developing new uniform suspended refueling units for the plane, since it lacked a bombing bay. The Su-24 was partnered with the Il-78 tanker.

Photograph from the official website of the Russian Federation Ministry of Defense


Since the late 1980s, in-flight refueling capabilities were built into all newly developed tactical aircraft, including the Su-24M, MiG-29, MiG-31, the Su-27 series, some MiG-25 models, and the heavy Tu-95MS, Tu-160, A-50, and Il-80 aircraft. New tankers were also developed, including fighter-tankers, as well as the new hope for Russian strategic aviation, a modified Il-78M.

The average time for in-air refueling lasts six minutes for helicopters, twenty minutes for bombers, and forty-five minutes for tankers.

In-air refueling of the Tu-95


The only enterprise in Russia currently working on in-air refueling systems is Zvezda, which is developing fuel receiver heads that are mounted on the booms of refueling aircraft, as well as several modified uniform suspended refueling units for tanker planes. They feature a hose 26-28 meters long with a flowing capacity of 1,600-2,900 liters per minute.

Photo ITAR-TASS / Vladimir Astapkovich

http://rostec.ru/en/news/4514547
Does Russia need transport and refueling aircraft and the corresponding removable refueling equipment? This question is rhetorical, of course. The length of Russia’s territory between Kaliningrad in the west to the Ratmanov Islands in the far east is about 8,000 kilometers. The possibilities for adapting and improving Russian aircraft to meet the challenges and necessity of long flights across oceans cannot be forgotten. Given the fact that in-flight refueling for the Russian Air Force is a very rare event, the need for further developing these systems is becoming even more urgent.

A-1H Skyraider VA-215 refueling VA-212 FJ-4B Fury in 1958

 

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Dual Wingtip Tank Refueling





An F-84 aligning with the drogue. Notice how far off center the pilot must look to line up the probe with the basket. Any turbulence would make this essentially impossible.


F-84 on the basket.







An F-84 refueling its right wingtip tank. Unknown cause of fuel spray, likely slosh from tank vent.


Refueling the left tank from the second probe.


F-84 refueling from KB-29


KB-29 refueling F-84E over Korea in 1952

Single Point Probe


F-84 with single point drogue refueling taking fuel from a KC-135.

 

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Boom and Receptacle


A receptacle equipped RF-84 pulls into the contact position behind a KB-29P


F-84 in contact with a KB-29P


High over West Texas, two F-84Gs of the 31st Fighter Escort Wing pull in behind a waiting KB-29P during Operation Fox Peter One. Note the opened receptacle on the upper surface of the left wing.


A F-84 taking fuel from a KC-97G using the boom and receptacle method of refueling.


An F-84 banks off to the right after refueling from a KC-97. Note the opened receptacle and drop tanks.


An excellent image of an F-84 pulling up behind a KB-29P. The KB-29P was the only tanker to have the boom operator situated above the boom. It was found difficult to align the boom from this position.
https://airrefuelingarchive.wordpre...eling-multiple-f-84-refueling-configurations/

F-84 Refueling from KC-97
Experimenting with jet refueling – Multiple F-84 refueling configurations