British escort fighter--what might it have been like?

[33k in the air]

Things that complicated life for all were paper drop tanks which had to be installed new but on day of mission because they leaked. But if enough 110s were available they were usually selected and filled night before, along with 65 gal for fuse tank.

Do you have any info on the empty weight of those 108 gallon paper drop tanks? They are reputed to be quite light, but I have never found an exact figure. The 75 gallon metal tank weighed 50 to 60 lbs empty, depending on the source, and the 110 gallon metal tank weighed about 85 lbs empty.

 

[33k in the air]

Two things I take from that.
1.The distance to the target flown by both bombers and fighters is much longer than the straight line distance to the target.

The websites for the 303rd and 451st Bomb Groups contains the planned route map for the mission. Based on the missions I reviewed, the distance flown was sometimes 20% or more than the straight line distance. The 25 June 1943 mission to Hamburg by the 303rd, for example, had a planned route distance of about 1,051 miles, as compared to a straight line out and back distance of about 880 miles.

(The ORBs for 77 Squadron contain the route flown from 1943 onward, so the planned route distance for that Bomber Command squadron can be calculated from that route info.)

 

[z42]

So the space between ribs 1 & 4 was not used for fuel tankage on any Spitfire variant so far as I can see. One thing that does possible intrude into that space is the undercarriage mounting which would attach to the rear of the wing spar.

This video

View: https://www.youtube.com/watch?v=Op8U7KQLxEQ&t=685s

mentions that near the wing root on the starboard side there is the gun camera, and on some early Mk IX on the port side there is an opening for a fuel cooler.

 

[PAT303]

Do you have any info on the empty weight of those 108 gallon paper drop tanks? They are reputed to be quite light, but I have never found an exact figure. The 75 gallon metal tank weighed 50 to 60 lbs empty, depending on the source, and the 110 gallon metal tank weighed about 85 lbs empty.

I don't know the weight but a man could hold an empty one over his head.

 

[PAT303]

The operational requirements dictated the instructions regarding the tankage - Everyone Knew the issues surrounding accelerated turns. The answer, "if you find yourself in a hard mauevering fight with full load, Go with God - but avoid that if possible'.

Figter pilots duly noted 'reports' and Tech Orders but they served, like regulations, only as a guide.

The same applied to the Spitfire, changing the rear tanks around and having the 33G on top and 42G on the bottom gives the Spit another 10G internal to play with and once the 60 series comes into production the power to lift the bigger 100G or 108-110G external extending it's range or loiter time.

 

[33k in the air]

I don't know the weight but a man could hold an empty one over his head. View attachment 745126

Yes, I've seen that photo before. It'd be nice to get an actual weight figure rather than having to guess the weight based on photos such as that one.

 

[ThomasP]

I do not have the weight for the bare 108 USgal paper tank, but the British version weighed 70 lbs with the fairing/pylon as used on the Hurricane. The 70 lbs includes all the bits except those in the wing that remained when the tank and fairing/pylon were dropped. This weight is from the modifications list for the Hurricane.

The 45 Impgal paper tank weighed 29 lbs bare, or 52 lbs including the fairing/pylon as used on the Hurricane. The 52 lbs includes all the bits except those in the wing that remained when the tank and fairing/pylon were dropped. The 52 lbs weight is from the modifications list for the Hurricane. The 29 lbs weight for the bare tank is from an industry magazine of the period.

 

[33k in the air]

The 45 Impgal paper tank weighed 29 lbs bare, or 52 lbs including the fairing/pylon as used on the Hurricane. The 52 lbs includes all the bits except those in the wing that remained when the tank and fairing/pylon were dropped. The 52 lbs weight is from the modifications list for the Hurricane. The 29 lbs weight for the bare tank is from an industry magazine of the period.

29 lbs for 54 US gallons (45 Imperial gallons) implies an empty weight of 58 lbs for the 108 US gallon paper tank, assuming the same ratio of empty weight to fuel weight (29 lbs / 324 lbs [54 gallons * 6 lbs per gallon] = 0.0895). That's 27 lbs lighter than the 110 US gallon metal tank. That doesn't seem to be as big a weight savings as I would have thought.

 

[NevadaK]

29 lbs for 54 US gallons (45 Imperial gallons) implies an empty weight of 58 lbs for the 108 US gallon paper tank, assuming the same ratio of empty weight to fuel weight (29 lbs / 324 lbs [54 gallons * 6 lbs per gallon] = 0.0895). That's 27 lbs lighter than the 110 US gallon metal tank. That doesn't seem to be as big a weight savings as I would have thought.

The weight isn't surprising. Glued laminated Kraft paper has a density somewhere between 30lb-40lb/cf. the technology is still in use today for construction, such as concrete formwork.

Sonotube Concrete Form - Fairbanks Materials Inc. (FMI)

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(No affiliation to the linked company)

These articles were informative

Necessity Is The Mother of Invention: Paper Drop Tanks of WWII

Faced with WWII metal shortages, the British came up with an ingenious design for drop tanks, making them out of glue-impregnated paper

warbirdsnews.com

WW2 Paper Drop Tanks

 

[don4331]

29 lbs for 54 US gallons (45 Imperial gallons) implies an empty weight of 58 lbs for the 108 US gallon paper tank, assuming the same ratio of empty weight to fuel weight (29 lbs / 324 lbs [54 gallons * 6 lbs per gallon] = 0.0895). That's 27 lbs lighter than the 110 US gallon metal tank. That doesn't seem to be as big a weight savings as I would have thought.

I was thinking the increase in tank weight would be proportional to the increased surface area (simplest is surface area of sphere - 4πr^2, so doubling volume increases surface area 2^0.5 or about 40%....call it 50% to allow increase in structure to attach to airframe. (Things like filler cap, etc are all identical) So <45lbs for 108 US gallon tank.. Not a huge difference, but we're gram counting here.

 

[ThomasP]

I have read that the US 108 USgal design variant weighed a bit more than the original UK type as there was additional hardware (dual filling ports and different hanger hardware for example) incorporated in the US design, but I have never been able to find the weight of the US variant.

The weights I gave above are for the original UK paper tanks.

 

[Admiral Beez]

Both Beaufighter and Boston were bad in bombing Germany.
British war started in 1939, not in 1941.

Germany is too far. But the Boston looks impressive bombing France.


View: https://m.youtube.com/watch?v=1LyqGo6dz2I