Why aerial refueling came too late for WWII?

DougM

Donor
The problem is very simple, where are you refueling the bombers (in the Eurpean theater) at?
To be of much use the refueling is going to have to be basically over Germany some place. But even today or during the height of the Cold War we did plan refueling over enemy territory.
So in order to avoid refueling over enemy held territory you have to basically refuel over England, so what is the point?

Now for long distance patrol that may be a bit different. But even then you are going to need a lot of tankers. As the tanker has to fly out and fuel the patrol craft then it returns while the patrol craft continues. But to get best range you need to refuel the patrol craft on the way back so you need another tanker.

If you look at what we do with refueling today you will find that it is not that useful in a WW2 setting. We use refueling to allow us to fly bombing missions from distant bases but usually the refueling aircraft are stationed closer to the destination. Of if flying from similar distance then it is a situation that we are flying missions from rediculus distance like B52s from the Continental US to the Middle East. And we only enter contested airspace in the last few hundred miles This was not the case in WW2. In general we got our air bases as close as we could to the target and thus we didn’t fly that far in uncontested airspace where we could refuel. Obviously the Pacific was a bit different but even then it was only flying raids from China to Japan that refueling would have helped and as stated the issue then is. The number of aircraft having to be refueled. The ability to find your tanker aircraft (especially hard to do on the outbound leg without giving away the refueling location) and the vulnerability of the refueling aircraft if detected.

As for the patrol aircraft. That is a bit different, you will note that today we tend to refuel small aircraft from large aircraft or we refuel large aircraft with heavy weapons loads from large aircraft with no weapons load. And neither of those really describe a patrol aircraft all that well. A patrol aircraft can be as large as you want to build it. It doesn’t need to maneuver that well and it needs little to no weapons. None if it is a scout and little if it is anti sub. So the reality is that the patrol aircraft will have extremely long range. So long that your tanker aircraft will have difficulty matching that range with enough fuel to refill the patrol aircrafts tanks.
Thank about this
Patrol Aircraft (called PC from here on) flys out X distance on internal fuel so Refueling Aircraft (RC) has to fly out X distance to refuel it. Assuming similar size aircraft of similar load that means RC needs to carry 3 times PCs fuel. As it needs to fly out X, back X and transfer X distance of fuel to PC. So in order to match this PC is has 2X of weapons. And that is over kill.
So if we say that PC has X +X fuel and X weight of weapons that means that you only get half the fuel from RC. So in order to double the range of the patrol Aircraft you need TWO tankers on outbound leg. Then you need two more on inbound leg.
So you need 4 tankers per Patrol and you need to find the second group of tankers in the middle of the ocean.
Good luck with that. Navigation was a pain over the open ocean in WW2 aircraft (Remember those lost Avengers out of Florida after the war?)
Frankly it would have been simpler to build tanker ships and flying boats or to just use baby Carriers.
 
Yet the Luftwaffe made zero effort to break up bomberswhen they were forming up

Because in real life the bombers were coming to them anyway so why risk losing fighters over the North Sea? In a scenario where the bombers are taking off a squadron at a time, refuelling over the sea then orbiting waiting for the rest of the bombers (and the fighter escort if it's an American daytime raid) to join them then it's worth risking a few fighters to try and take the refuelling aircraft out, leaving many of the bombers without enough fuel to reach their target.

Edit - I'm sure the Luftwaffe did try sending intruders over to interfere with RAF bombers returning to base from raids over Germany so it's not beyond the realms of belief for them to risk a handful of fighters to take down a tanker or two and disrupt an entire bombing raid.
 
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If you are refueling a squadron at a time and then orbiting to wait until everyone else has fueled up, a lot of the extra fuel in the first squadrons to fuel up is wasted flying in circles. Even if you had the tech for flying boom and probe and drogue, it doesn't work. Once you had refueling tech up and running you were not looking at needing to refuel hundreds of aircraft in the same place at the same time for these sort of massive raids. Not even dozens in the same place/time. Every tanker you build in WWII is one less bomber you have, and the extra bombload per mission is not worth it - the reality is if any bomber now carries 50% more bombs, accuracy is not improved and dumping 50% more ordnance away from the target is not a benefit. Extra fuel won't reduce the loss ratios, and now you have fewer bombers because you have KB-17/24/29 replacing bombers 1:1.
 
If you are refueling a squadron at a time and then orbiting to wait until everyone else has fueled up, a lot of the extra fuel in the first squadrons to fuel up is wasted flying in circles. Even if you had the tech for flying boom and probe and drogue, it doesn't work. Once you had refueling tech up and running you were not looking at needing to refuel hundreds of aircraft in the same place at the same time for these sort of massive raids. Not even dozens in the same place/time. Every tanker you build in WWII is one less bomber you have, and the extra bombload per mission is not worth it - the reality is if any bomber now carries 50% more bombs, accuracy is not improved and dumping 50% more ordnance away from the target is not a benefit. Extra fuel won't reduce the loss ratios, and now you have fewer bombers because you have KB-17/24/29 replacing bombers 1:1.

Why not KC-47?
 
accuracy is not improved and dumping 50% more ordnance away from the target is not a benefit.

but aircrew exposure to German fighters is lessened.
a cut-n-paste
d. In the fall of 1944, only seven per cent of all bombs dropped by the Eighth Air Force hit within 1,000 feet of their aim point; even a ‘precision’ weapon such as a fighter-bomber in a 40 degree dive releasing a bomb at 7,000 feet could have a circular error (CEP) of as much as 1,000 feet.8 It took 108 B-17 bombers, crewed by 1,080 airmen, dropping 648 bombs to guarantee a 96 per cent chance of getting just two hits inside a 400 x 500 feet German power-generation plant; in contrast, in the Gulf War, a single strike aircraft with one or two crewmen, dropping two laser-guided bombs, could achieve the same results with essentially a 100 per cent expectation of hitting the target, short of a material failure of the bombs themselves.9

To better appreciate the impact - no pun intended - of precision weaponry, it is only necessary to examine trends in bombing accuracy from increasingly accurate bombing platforms equipped with increasingly advanced sighting systems used to dispense dumb bombs. The following chart looks at the case of trying to hit, with a hit probability of 90 per cent, a target measuring 60 x 100 feet using 2,000 pound unguided bombs dropped from medium altitude:10



Number of Bombs
9,070
Number of Aircraft

3,024
CEP (in feet)

3,300



Now for that example
For example, in the summer of 1944, 47 B–29s raided the Yawata steel works from bases in China; only one plane actually hit the target area, and with only one of its bombs. This single 500 lb general purpose bomb (which hit a powerhouse located 3,700 feet from the far more important coke houses that constituted the raid’s aiming point) represented one quarter of one per cent of the 376 bombs dropped over Yawata on that mission.7

Here that would be either a 1000 pounder, or a 2nd 500 pounder hitting nearby

and here it could be 54 B-17 Bombers, crewed by 540 airman, dropping 648 bombs to get that 96% chance
 
Why not. Thing is that a transport aircraft can do it, no need to divert bomber production. The C-47 was most numerous, others, like C-46 and C-54 will do it even better.
There are a few reasons that using a B-24 airframe makes sense. They all involve capacity.

if you increase bombloads with in-flight refueling, you need fewer bombers. This means B-24 production is freed up.

Adopting the C-109/B-24 might have an overlooked advantage: a ready tail station. Presumably a tail observation position would be very useful. The tail gunner’s position is there, so little or nonew engineering is needed.

Perhaps the biggest is production capacity. There is simply more production capacity available for a dedicated C-109. This is especially if inflight refueling decreases the absolute numbers of bombers needed, freeing up bomber capacity.

Douglas only made 1100 C-54s. Willow Run alone a it’s peak could produce 1100 B-24s in about 6 weeks. (1 B-24/hour 24 hour/day x 7 days/week x 6 weeks = 1080 B-24). As were two other companies building B-24s, which together made even more than Willow Run, the introduction of a dedicated inflight C-109 variant should be pose a minimal disruption in the supply of boomers.

Further, the production rate should be at least as good as for a tanker as for a bomber if the USAAF can come up with good design (and doesn’t try to gild the lily).An inflight tanker version should be at least as easy, and probably easier, to build than as the B-24. The tanker would lack turrets and gunnery equipment, bomb handling equipment, bombardier station, armor, probably no turbosuperschagers, fewer crew stations, etc. on the other hand, a dedicated tanker version of the C-109 would need cargo tankage fuel, handling equipment, and probably a reconfiguration of the tail gunner site to the fueler’s position.

One big bottle-neck in this would the fuel transfer system. Developing a suitable system in a timely fashion and producing it in quantity would be hard. I can imagine that.this would result in no new civilian filling station gas pumps being made for two years.

The other big bottle-neck to implementing this is the aircrew training. I’d think this would require more than few practice runs.


Anyway, I hope this makes sense. Please excuse any elisions or typos, as I wrote this on my phone.
 
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trurle

Banned
Yet the Luftwaffe made zero effort to break up bomberswhen they were forming up
Freya/Mammut was easily jammed, and British used radar jammers systematically.
Mammut had a range of 300km from 1942 (per Wiki). That's enough to pick up a huge, slowly orbiting formation of bombers over the North Sea/east coast of England from the Dutch coast.
I doubt the cited range. 300km is simply radio horizon for 6000m high flights. Targets would be deep inside ground&sea clutter at 300km. I estimate maximal range of 220 km@6000m (and in 100-degree sector only for Mammut)
 
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There are a few reasons that using a B-24 airframe makes sense. They all involve capacity.

if you increase bombloads with in-flight refueling, you need fewer bombers. This means B-24 production is freed up.

Adopting the C-109/B-24 might have an overlooked advantage: a ready tail station. Presumably a tail observation position would be very useful. The tail gunner’s position is there, so little or nonew engineering is needed.

Perhaps the biggest is production capacity. There is simply more production capacity available for a dedicated C-109. This is especially if inflight refueling decreases the absolute numbers of bombers needed, freeing up bomber capacity.

Douglas only made 1100 C-54s. Willow Run alone a it’s peak could produce 1100 B-24s in about 6 weeks. (1 B-24/hour 24 hour/day x 7 days/week x 6 weeks = 1080 B-24). As were three other sites building B-24s, which together made even more than Willow Run, the introduction of a dedicated inflight C-109 variant should be pose a minimal disruption in the supply of boomers.
...

I'm trying to get as much bombs on Axis assets in as short period of time, in flight refueling provided by other A/C types might help me ;)
B-24 acceptance beat the 500/month mark in August of 1943, it peaked at 964 by mid-1944. We know that B-24s were used in Asia/Pacific, MTO and ETO, plus to plug Atlantic gap by 1943 - makes them a much needed part of Allied war effort.
In mid-1943, ~200 of DC-3-type transports were accepted by USAAF, that rose to 400-500 by early 1944. Granted, production/acceptance of C-46 and C-54 were just a drop in the sea, though each of these will carry about twice, if not more than C-47.
 
though each of these will carry about twice, if not more than C-47.
B-18-N52056-56-Mel-Christler-KOM.jpg


converted B-18, the Bomber version of the DC-3
quickly overshadowed by other surplus types for waterbombing. 1000 Gallons
 
I'm trying to get as much bombs on Axis assets in as short period of time, in flight refueling provided by other A/C types might help me ;)
B-24 acceptance beat the 500/month mark in August of 1943, it peaked at 964 by mid-1944. We know that B-24s were used in Asia/Pacific, MTO and ETO, plus to plug Atlantic gap by 1943 - makes them a much needed part of Allied war effort.
In mid-1943, ~200 of DC-3-type transports were accepted by USAAF, that rose to 400-500 by early 1944. Granted, production/acceptance of C-46 and C-54 were just a drop in the sea, though each of these will carry about twice, if not more than C-47.
It's a numbers game, with one limiting factor being crew numbers. A C-109 could carry 2900 gallons of fuel. Gasoline weighs 6.3 lbs/gallon. A C-109 dedicated to refueling, with an crew man or two and the fueling equipment might be able to carry 2400 gallons.

A B-17G carried a maximum fuel load of 1700 gallons and a maximum bomb load internally of 8000 lbs--but not at the same time. Let's assume that to get to Berlin with 4000 lbs, you'd 1300 gallons. There were probably tables with range v. maximum bomb load someplace but I don't have them at a moment. As @marathag has noted the real limiting factor is take off weight, with the maximum is around 60-65,000 lbs. If you swap 650 gallons of fuel (about 4100 lbs) at take for 3500 lbs of bombs, then add 650 gallons after take-off(or more, as quite few gallons were burnt on take-off) by inflight refueling, you've increased bomb loads by over 85% per bomber. Even if you add-in the C-109s involved (assuming that 1 C-109 refuels 3 B-17s), you've increased the bombload for 4 aircraft involved from 16000 lbs to 22500 lbs, an increase of over 40%. Now, this is just a very rough estimate. But assuming that's it close to correct, the USAAF would be able to put considerable number more bombs on target with fewer aircrews.

That said, there numerous barriers that would prevent this from ever being a reality, starting with training and equipment. The USAAF would've had to begun this idea pre-war to have viable in time for the summer or fall of 1943.
 
B-18-N52056-56-Mel-Christler-KOM.jpg


converted B-18, the Bomber version of the DC-3
quickly overshadowed by other surplus types for waterbombing. 1000 Gallons

I'm thinking it's a good thing the photographer didn't request these men to step back a little.
It appears to me that they are standing only 5 or 6 feet in front of that turning propeller.
 
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My suggestion was not that one squadron be refueled at a time, but rather that each squadron formation was refueled in a seperate area before forming up into the raid formation.

I’m thinking a tanker based on a C47 or C54 would be better then one based on the B-24, you are less likely to lose airframes due to them going outside the designed CoG envelope.
 
My suggestion was not that one squadron be refueled at a time, but rather that each squadron formation was refueled in a seperate area before forming up into the raid formation.

I’m thinking a tanker based on a C47 or C54 would be better then one based on the B-24, you are less likely to lose airframes due to them going outside the designed CoG envelope.


Yes and no. The B-24 based C-87 transport had a problem with out of limits C of G when incorrectly loaded with cargo. The C-109, another transport plane based on the B-24, was specialized for fuel transporting. Because of the density load nature of gasoline it didn't take up the entire cargo bay. The maximum weight of fuel cargo the C-109 could carry was placed in tanks installed in the location of where the bomb bays were on a B-24. This kept the C of G within the designed limits.

I would imagine a C-109 could be modified to serve as a ATA tanker without too much trouble. But there is another consideration. And this would apply to the C-109 as well as C-47, C-54 or other aircraft used in tanker conversions. The volatility of gasoline vapours. Whatever amount of piping and plumbing, valves and pumps that would be fitted to these planes it must be done with high quality work and materials. There were many incidents of planes like the C-109 or the C-46 exploding in midair with no obvious cause.
 
There were many incidents of planes like the C-109 or the C-46 exploding in midair with no obvious cause.
Oh, it was obvious.

I knew a B-24 Pilot who said they were notoriously leaky with the regular tanks.

He said one of his rises leaked so bad, they had to slightly roll one of the bay doors up a bit, just so the slipstream would suck out the gas vapor that would build up. It was bad enough at times they could still notice it when on oxygen.

So add that, plus extra tanks, to see why they got tagged with' See One oh Exploder'
 
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