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Thread: Feasibility of in-flight refuelling during WW2

  1. #16
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    Perhaps it's best use would be to close off the Atlantic to U-Boats, but that wouldn't really have been necessary, would it? The Liberator was doing a pretty good job of that without inflight refueling.......


  2. #17
    IP/Mech THE GREAT GAZOO FLYBOYJ's Avatar
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    Quote Originally Posted by Junglerot View Post
    I must respectfully disagree with Flyboy. In flight refueling was practical for large aircraft during the war. The hose and reel system was used pre-war to refuel Short Empire flying boats which was a large a/c by any standard. The first generation system required the fueling aircraft to trail a line to the tanker aircraft and then winch back the hose and manually connect it to the fueling system. I don't see this being practical on a smaller aircraft. I think Flyboy overemphasizes training issues. The RAF crews flying in the PTO would presumably have been experienced pilots who could have quickly picked-up the refueling skill sets needed at the same time they were training for long overwater flights. The USAF crews who flew the first non-stop circumnavigation flight had very little training in inflight refueling. While the hose and reel system system was inefficient compared to more modern systems, it was practical and had been used on transatlantic flights. It could reasonably have been expected to have been successfully used by the RAF in bombing Japan. Whether fielding Halifax tankers to Lancaster bombers at a 1:1 or 1:2 ratio would have been practical is another question. The British tended to underestimate the logistical issues of the Pacific war and I'm not sure where they would have parked all of those aircraft.
    Have you ever spoken to or worked with pilots who did air to air refueling? I have and I also worked on a "civilian tanker."

    Omega Air Refueling

    It's not something as easy to learn just by routine training and after it is learned you have to continually stay proficient at it. The Post war B-50 flights actually introduced the first US crews in a modern era to what was to come and air to air refueling didn't really mature in the USAF until the 1950s. Those flight were more of a demonstration of potential that did evolve pretty quick (after some trial and error) In a war time situation it's not as easy as you might make it out to be.

    The equipment, although developed at the time wasn't refined until after WW2 (although the urgency of the war might have expedited development).

    When you say "experienced pilots," how many hours are you assuming? I know for a fact that because of the type of bombing done by the RAF during WW2 heavy bomber formation flying in tight quarters (one aspect of air to air refueling) wasn't something accomplished on a regular basis. Additionally with regards to the RAF planning air to air refueling in the PTO - a single pilot multi engine aircraft performing long range flights and introducing air to air refueling is an accident risk that probably outweighs the end benefits. Again possible but not effective with a lot of high risk mitigation to be dealt with.
    Last edited by FLYBOYJ; 04-21-2013 at 03:41 PM.

  3. #18
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    A couple of basic problems:-

    a) Fuel is heavy stuff, I believe around 7ib a gallon, what aircraft can carry that sort of weight once you have allowed for the tanks, pumps, hoses, etc and still carry a decent volume.

    b) The receiving aircraft of any type, will need total redesign

    c) The impact of all this extra weight on the performance of the receiving aircraft and the payload range of the tanker aircraft.

    Training I believe would be possible but it takes a long time and constant practice, even today with all the technology and experience it still goes wrong and pilots wash out because the cannot manage it.

  4. #19
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    Quote Originally Posted by Glider View Post
    A couple of basic problems:-

    a) Fuel is heavy stuff, I believe around 7ib a gallon, what aircraft can carry that sort of weight once you have allowed for the tanks, pumps, hoses, etc and still carry a decent volume.

    b) The receiving aircraft of any type, will need total redesign

    c) The impact of all this extra weight on the performance of the receiving aircraft and the payload range of the tanker aircraft.

    Training I believe would be possible but it takes a long time and constant practice, even today with all the technology and experience it still goes wrong and pilots wash out because the cannot manage it.
    A "biggie!"

  5. #20
    Pacific Historian syscom3's Avatar
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    There were some serious studies that were being done by the engineering staff's in the PTO "Air forces" for mid air refueling for the B24's. Their perceptive was that a few hundred gallons of fuel in air could greatly help their operations that were long ranged anyway. A couple more hours of range, a bigger bomb load, lower takeoff weights, or better fuel reserves was what they wanted and were willing to get.

    Since most of the operations in the PTO were over water, war weary B24's would be converted to tankers, and escort the bombed up B24's part way and top off their tanks after a few hours of flying. There was no need for fighters to escort them.

    I think the 5th BG even proposed a system like that for a B24 to fly on a one way mission from Midway, bomb Japan and land in China.
    Last edited by syscom3; 04-21-2013 at 06:03 PM.
    "Pilot to copilot..... what are those mountain goats doing up here in the clouds?"

  6. #21
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    An interesting history of in-flight refuelling:

    http://www.afhso.af.mil/shared/media...100929-015.pdf

  7. #22
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    Quote Originally Posted by RCAFson View Post
    An interesting history of in-flight refuelling:

    http://www.afhso.af.mil/shared/media...100929-015.pdf
    I was just reading that!
    Quote Originally Posted by syscom3 View Post
    There were some serious studies that were being done by the engineering staff's in the PTO "Air forces" for mid air refueling for the B24's. Their perceptive was that a few hundred gallons of fuel in air could greatly help their operations that were long ranged anyway. A couple more hours of range, a bigger bomb load, lower takeoff weights, or better fuel reserves was what they wanted and were willing to get.

    Since most of the operations in the PTO were over water, war weary B24's would be converted to tankers, and escort the bombed up B24's part way and top off their tanks after a few hours of flying. There was no need to escort them.

    I think the 30th BG even proposed a system like that for a B24 to fly on a one way mission from Midway, bomb Japan and land in China.
    Just after Pearl Harbor, the U.S. Army Air Forces began working on an air refueling solution. With the help of Hugh Johnson, the man who had been in charge of FRL's Gander operations, they studied three primary concepts. First, planners looked at launching B-17 Flying Fortresses from Midway Island against Japan, with the idea of using modified B-24 Liberators as tankers. Second, they considered using B-24s from Hawaii with tanker support from U.S. Navy seaplanes. The third concept called for B-17s to tow fuel-laden gliders to serve as tankers.

    Testing -- using a variation of the looped-hose method -- began in the summer of 1943 at Eglin Field, Fla. A B-17E served as the receiver and a modified B-24D as the tanker. The successful tests extended the B-17's range (with three tons of bombs) from 1,000 to 1,500 miles.

    The problem now was how would the country's taxed manufacturers build the equipment for squadrons of B-24 tankers and B-17 receivers? Added to this dilemma was the time required for the aircraft modifications and crew training. Additionally, by mid-1943, Boeing began rolling out the B-29 Superfortress. The B-29 had a combat radius of 1,500 miles and carried twice the bomb load of the B-17.

    In 1944, the U.S. Army Air Forces began studying the feasibility of equipping B-29s with an air refueling capability. The engineers at Wright Field, Ohio, determined it was possible to modify the aircraft, but the 1,500-gallon capacity of a B-24 tanker only


    http://www.amc.af.mil/news/story.asp?id=123133645
    Last edited by FLYBOYJ; 04-21-2013 at 05:19 PM.

  8. #23
    Junior Member Junglerot's Avatar
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    Flyboy, I did not mean to imply that inflight refueling would have been easy, just that it was doable, had been done, and was planned to be done on a relatively large scale with technology that was available during the war.

    As far as "experienced" RAF aircrews I did not have any particular hour figure in mind, I was just thinking that the RAF was demobbing most of Bomber Command and Coastal and that Tiger Force would have had their pick of aircrew who wanted to make a career in the RAF or keep their hand in the game until commercial jobs opened up.

    Yes I understand the refueling is difficult but as you point out so are carrier ops and thousands of pilots were qualified for this during the war after relatively quick training. Many of these pilots wouldn't have qualified under peacetime standards but higher operational casualty rates we acceptable at the time.

    I also believe that the difficulties of converting bombers into tankers has been overstated in this thread. We are not talking about really good tankers just wartime expedients. Think about the fuel systems on the Doolittle raiders and how low the standard for usability was.

  9. #24
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    Quote Originally Posted by Junglerot View Post
    Flyboy, I did not mean to imply that inflight refueling would have been easy, just that it was doable, had been done, and was planned to be done on a relatively large scale with technology that was available during the war.
    I think we're in somewhat agreement there. My point "doable" but not practical or efficient.
    Quote Originally Posted by Junglerot View Post
    As far as "experienced" RAF aircrews I did not have any particular hour figure in mind, I was just thinking that the RAF was demobbing most of Bomber Command and Coastal and that Tiger Force would have had their pick of aircrew who wanted to make a career in the RAF or keep their hand in the game until commercial jobs opened up.
    Perhaps, but again there would have been training required, and even if you had a pilot with flight hours in the low four digits, it's not a matter of a few hours and you have effective air to air refueling capability. It took the USAF years to evolve it's tanker force where air to air refueling could have been done effectively and more importantly, safely...
    Quote Originally Posted by Junglerot View Post
    Yes I understand the refueling is difficult but as you point out so are carrier ops and thousands of pilots were qualified for this during the war after relatively quick training. Many of these pilots wouldn't have qualified under peacetime standards but higher operational casualty rates we acceptable at the time.
    And the same situation could have happened for air refueling crews. I think the war planners at the time knew this, more reasoning why it never happened.
    Quote Originally Posted by Junglerot View Post
    I also believe that the difficulties of converting bombers into tankers has been overstated in this thread. We are not talking about really good tankers just wartime expedients. Think about the fuel systems on the Doolittle raiders and how low the standard for usability was.
    Again, I don't know how much aircraft experience you have - first would you want to regularly fly and place your and your crew's life on an aircraft that had a system designed as a "wartime expedient?" The Doolittle raid was a "one shot" deal and the crew accepted the risk to complete the ONE mission. I guarantee that even by WW2 standards, operational practices would not have been allowed in the matter conducted during the raid, engineering officers would have been pounding on Arnold's door daily!

    I worked on a 707 that had a "bolt on" drogue system so the aircraft's capability could be hidden. That mod took quite a long time to design and implement. Again, I don't know if you have worked on aircraft but I could tell you first hand that converting bombers into tankers is not and easy undertaking, and I think the link I posted clearly shows the consideration and the reasons why air to air refueling was not adopted during WW2.

  10. #25
    Senior Member davebender's Avatar
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    biggest hurdle would have been training crews

    I agree.

    Peacetime trained crews (i.e. late 1930s) could conduct in flight refueling but it's asking too much from typical green WWII trained pilots.

  11. #26
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    Quote Originally Posted by davebender View Post
    I agree.

    Peacetime trained crews (i.e. late 1930s) could conduct in flight refueling but it's asking too much from typical green WWII trained pilots.
    And look into some of the systems used in the 1930s when compared to the post war years. In the 30s air to air refueling was being done at low speeds and altitudes. Just compare some of the equipment - the reels, hoses and the drogue connectors.

  12. #27
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    What would be the point of extending the range of the bombers, if you couldn't do the same for the escorts.
    The bombers already could outrange their escorts, and proved they couldn't survive without protection.
    And the looped hose method wasn't doable by a single engine fighter, no matter how much training.

    Aerial refueling might have been useful in a few situations, extending patrol distances , but at it state of the art in WW2, I don't see a use for it in combat situations.

  13. #28
    Senior Member vikingBerserker's Avatar
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    In Luftwaffe Over America page 154, one of the approaches Germany played with was a simple method. A tanker would real out a hose, to be caught by a fork shaped device on the receiving aircraft. This fork would be retracted and a crew member would manually attach the hose to the fuel tank and refuel. There was minimal changes to the receiving aircraft. The downside is it's not exactly the safest way of doing it. Germany had converted Ju-86s and Ju-290 as tankers during the tests.



  14. #29
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    Quote Originally Posted by vikingBerserker View Post
    In Luftwaffe Over America page 154, one of the approaches Germany played with was a simple method. A tanker would real out a hose, to be caught by a fork shaped device on the receiving aircraft. This fork would be retracted and a crew member would manually attach the hose to the fuel tank and refuel. There was minimal changes to the receiving aircraft. The downside is it's not exactly the safest way of doing it. Germany had converted Ju-86s and Ju-290 as tankers during the tests.
    Basically introducing open fuel into the cabin area. That used to happen on the B-24 and on the Martin Mariner, the end result wasn't pretty.

  15. #30
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    I've noticed even on modern aerial refueling when they disconnect, you see a spray of fuel. A little residual fuel left in the line I guess.
    Not something you'd want floating around the cabin for the rest of a mission.

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