Feasibility of in-flight refuelling during WW2

[wuzak]

I know that tests were done with in-flight refuelling before and during ww2, but how feasible was it for WW2?

Could single engine fighters do it, or was it only for multi-engine types during that period.

 

[Junglerot]

It was practical in WWII. A British company called Flight Refueling Ltd. developed a reasonably practical system before the war and the RAF was planning to use the system for refueling Lancs in the PTO. The USAF used an improved version of the system in 1949 to fly B-50 around the world non-stop. I don't know that much about the weight and bulk of the system, but it seems to only have been suitable for large multiengine a/c with aircrew manually connecting the fuel line in the early versions of the system. In addition a single engine a/c with a tractor prop is going to present issues with the prop slicing up the refueling hose. All that being said, I think that if in-flight refueling had been a major r&d priority for the allies, there could have been more practical systems suitable for use by smaller a/c by the end of the war.

 

[wuzak]

For single engined aircraft I would imagine that the filling point would be on the wing, well outside the prop arc. But if it had to be manually connected then it wouldn't be possible.

 

[Junglerot]

I did not mean to imply that it is impossible to refuel single engine a/c in flight, just stating that it presents design issues. The US Army refueled DH-4s in flight during the 1920s so it definitely can be done.

 

[vikingBerserker]

Germany was very successful using a drogue type system refueling multi engine aircraft in 1942 and 43. They were working on it to extend the range of bombers to reach America. However with the progress of the war it was too late. There was talk of extending this ability to single engine fighters but it does not appear to have progressed very far.

 

[Jenisch]

Interesting. If 100 fighters could have been refuled in the air, it woud already represent something for the fighter force in the ETO before long-range escorts appeared.

 

[GregP]

It would definitely be a probe and drogue type thing, and might be possible, but I don't think anyone would fly big, slow tankers (B-24, B-29?) over hostile territory and try to refuel multiple aircaft in a row for 150+ miles at a time (probably WOULD encounter enemy aircraft or fly over flak or observer in that time), so I don't think it would be practical unless the refuelling area was SECURE. That precludes refuelling over areas where Axis fighters would be. Europe would be really iffy ...

Might be practical for the Pacific regions, where you could reasonably be secure with escorts over open ocean and reconaissance support, but fairly impractical in Europe where German fighters lived in abundance. Might be just fine over the Altantic Ocean, but I'd avoid the Med due to local Axis fighter strength. Would work over Alaska and the Aleutians, and maybe in places in the CBI.

That assumes a good probe and drougue setup.

 

[wuzak]

Would help range, a little, if done over the UK. Refill the tanks after the warm-up, take-off and initial climb.

Could have been useful for the early bombers to go aloft as they wait for the rest to climb and form up.

 

[Shortround6]

For Europe it wouldn't do anything the drop tank wasn't already doing.

The tankers are NOT going to fly much past the channel, so actual range extension is only going to be around 100 miles.

It might help nursing some cripples back to dry land though, both fighters and bombers.

Trying to refuel several fighter groups (48 planes per group) is going to be a zoo show. How many tankers per fighter group do you need to refuel in a timely fashion?

 

[wuzak]

What about a sort of FICON?

Except not the wingtip to wingtip deal. Maybe a B-17 with a Spit on each wing.

 

[Jenisch]

The existent escort allowed the fighters to go until Holland, isn't? What about if this escort goes, but the the air refuled one goes by the ocean, refuels there and in the border between Holland and Germany it appears?

A problem would be the LW attack the tankers, but I express confidence that the escort already in Holland would reduce the chance of the LW get close to the tankers (which also would be protected by the planes they were refuling. A good alternative would be mix tankers and conventional bombers).

Anyway, this wasn't done because it was not needed. By the time of the heavy losses inflicted in the daylight bombers, the P-51B was already work in progress, and it would not compensante to implement all the logistics and training to operate tankers.

 

[FLYBOYJ]

It was practical in WWII. A British company called Flight Refueling Ltd. developed a reasonably practical system before the war and the RAF was planning to use the system for refueling Lancs in the PTO. The USAF used an improved version of the system in 1949 to fly B-50 around the world non-stop. I don't know that much about the weight and bulk of the system, but it seems to only have been suitable for large multiengine a/c with aircrew manually connecting the fuel line in the early versions of the system. In addition a single engine a/c with a tractor prop is going to present issues with the prop slicing up the refueling hose. All that being said, I think that if in-flight refueling had been a major r&d priority for the allies, there could have been more practical systems suitable for use by smaller a/c by the end of the war.

Although it may have seemed possible, there were many issues that would have prevented it from being effectively utilized. The hose and reel system (drogue) did not offer a rapid fuel flow into the receiving bomber, that's why it was more tailored to smaller aircraft. The refueling boom was a major breakthrough making air to air refueling more effective and practical.

The biggest hurdle would have been training crews to perform air to air refueling, one of the hardest things military pilots have to do besides landing on an aircraft carrier. It is not an easy task even with the drogue system. To sum it up, could have been possible to perform air to air refueling during WW2? Yes - would have been practical or effective? With history hindsight being 20-20, I doubt it.

 

[Shortround6]

You may be back to the drop tank problem. You may be able to get the fighters further into enemy territory than they can get themselves back out.

If plane XX needs 150 gallons of internal fuel to fight and get home at a reasonable (survivable) speed from distance YY it doesn't matter how big the drop tank is that it carries on the way in or how it "nurses" from a a bigger plane (unless it can hook up again on the way out). but that is a vulnerable combination in a non-aircraft radar environment with lots of clouds.

 

[Jenisch]

That's what I said, Flyboy: just because some months until the P-51 arrived, it would not compensante.

 

[Junglerot]

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.

 

[glennasher]

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.......

 

[FLYBOYJ]

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.

 

[Glider]

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.

 

[FLYBOYJ]

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!"

 

[syscom3]

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.