Empty weight of drop tanks

[33k in the air]

Does anyone have any data on the empty weight of drop tanks used during WWII? I'm particularly interested in knowing how the empty weight of the 108 gallon 'paper' drop tank used in the ETO compared to the empty weight of the 108 gallon metal drop tank and the later 110 gallon teardrop-shaped tank. But information on any other drop tanks would be welcomed also.

The technical aspects of drop tanks in general, other than their capacity, seems little covered either in print or online, at least, based on my search attempts.

 

[MiTasol]

This is all I have, pretty poor quality. If you find the rest of this manual, and/or and earlier/later edition, can you please post it here

 

[ThomasP]

This is what I have:

Hurricane
45 Impgal____77 lbs, metal (SSFT), cylindrical, fixed, combatable (includes fairing)
45 Impgal____52 lbs, paper, cylindrical, (includies fairing)
90 Impgal____98 lbs, metal, cylindrical, fixed (normally), ferry (includes fairing)
90 Impgal____70 lbs, paper, cylindrical, (includes fairing)

Spitfire
30 Impgal____75 lbs, steel, slipper, combatable
30 Impgal____40 lbs, SEMA 4 (SSFT), slipper, combatable
90 Impgal___142 lbs, steel, slipper, ferry (combatable if empty?)

Fulmar
60 Impgal___118 lbs, steel, slipper, combatable

Mosquito
42 Impgal____60 lbs, steel, slipper, combatable if empty
50 Impgal____38 lbs, wood, slipper, combatable if empty
80 Impgal____82 lbs, steel, slipper, combatable if empty

F4F Wildcat/Martlet
58 USgal____ 38 lbs, steel, teardrop (45 lbs including hanger bits)

F4U Corsair/F6F Hellcat
100 USgal__ 104 lbs, steel, streamlined
150 USgal__ 122 lbs, steel, streamlined
150 USgal__ 194 lbs, steel (SSFT), streamlined, combatable

TBF Avenger/SB2C Helldiver
100 USgal____71 lbs, steel, teardrop

P-38 Lightning
110 USgal____85 lbs, steel, teardrop
165 USgal___106 lbs, steel, streamlined
300 USgal___140 lbs, aluminum, streamlined
310 USgal___176 lbs, steel, streamlined

P-39 Airacobra
175 USgal___150 lbs, steel, conformal
175 USgal___155 lbs, steel, conformal

P-51 Mustang
75 USgal____ 50 lbs, steel, teardrop

A6M Zero
72 Impgal____72 lbs, composite, combatable

Ki-43 Oscar
44 Impgal____58 lbs, metal, teardrop
44 Impgal____53 lbs, metal, teardrop

 

[ThomasP]

Added Fulmar DT and Mosquito DT to above post.

 

[33k in the air]

I'll add what I've come across. The following is from Mustang: The Story of the P-51 Fighter by Robert W. Gruenhagen.

75 gal. combat tank = 60 lbs
150 gal. ferry tank = 120 lbs
165 gal. ferry tank (P-51H) = 135 lbs
110 gal. combat tank = 75 lbs

From Spitfire: A Documentary History by Alfred Price. Pages 132-133 include a weight breakdown of the Spitfire F.21 which includes the following figures for the empty weight of drop tanks:

30 gal. drop tank = 60 lbs
45 gal. blister type drop tank = 80 lbs
90 gal. blister type drop tank = 120 lbs

I'm not sure exactly what is meant by "blister type drop tank". I presume it's a reference to the torpedo-shaped type of drop tank.

 

[tomo pauk]

I'm not sure exactly what is meant by "blister type drop tank". I presume it's a reference to the torpedo-shaped type of drop tank.

Blister was the 'flush-fitting' type. Like this on the model, under the fuselage.

 

[33k in the air]

Blister was the 'flush-fitting' type. Like this on the model, under the fuselage.

Ah, okay. Isn't it basically the same as a slipper tank only bigger?

 

[MiTasol]

Blister = slipper = conformal depending on which manual or drawing you are looking at.

 

[33k in the air]

Some more drop tank weights I've come across. The following quotes are from the Nov. 4th, 1943, issue of Flight magazine.

To provide extended fighter cover and to increase the time limit on operational sorties, the Hurricane and Typhoon fighters have fitted beneath each wing a 45-gallon metal drop tank, each approximately 7ft. long by 15in. diameter and weighing 29 lb. empty.

The Lockheed Lightning . . . continues on those lines by having two drop tanks, each fitted beneath the centre section between and nacelles. These tanks are constructed of 23 S.W.G. (0.024in.) sheet steel ; they have a capacity of 150 gallons each and weigh 90 lb. empty . . . The Lightning tanks are 10ft. long by 27in. maximum cross-sectional diameter, and are made up in two half-shell pressings, seam-welded together. Seven transverse bulkheads are welded-in, and the attachment points for connection to the aircraft are in a recessed trough on the top curvature of the tanks.

 

[33k in the air]

Lastly, drop tank weights as determined from the weight loadout tables published in America's Hundred Thousand by Francis H. Dean.

51 gallons (F4U-1) = 40 lbs
52 gallons (P-40C) = 54 lbs
58 gallons (F4F-4, FM-2) = 50 lbs
75 gallons (P-39Q-1) = 45 lbs
75 gallons (P-47D) = 50 lbs
75 gallons (A-36A-1, P-51A, P-51D) = 60 lbs
91 gallons (P-39D-2) = 45 lbs
110 gallons (P-51D) = 90 lbs
150 gallons (F4U-1D) = 79 lbs
150 gallons (A-36A-1, P-51A) = 105 lbs
150 gallons (P-63A-10) = 120 lbs
159.33 gallons (F4U-1) = 78.5 lbs
165 gallons (P-47D, P-38J) = 87.5 lbs
165 gallons (P-51D) = 115 lbs
175 gallons (F4U-1) = 95 lbs
300 gallons (P-47D) = 157 lbs
306 gallons (P-61B) = 222 lbs
312 gallons (P-38J) = 155 lbs

 

[ThomasP]

Added P-38 110 USgal steel DT & 300 USgal aluminum DT, and P-39 175 USgal steel DT to my post#3 above.

 

[ThomasP]

Made correction to my post#3 above. I had the weight of the 58 USgallon DT listed as 54 lbs with hanger bits, but I made a typo and reversed the 5 & 4. The weight with hanger bits should be 45 lbs.

 

[PierreDeveaux]

Greetings to all,

First of all, thanks a million for sharing so much historical background data and comment - ww2aircraft.net is a gold mine.

I realize this particular subject is over 3 years old but it so happened I recently "bumped" on it when, searching for something completely different, Google showed a 150 gal (150.US in my own parlance) associated with a P-51 Mustang hm... not to my knowledge was my thought so I suspended whatever i was doing to check/update whichever notes I had. A specific search to supplement this update lead me to this page. If I saw it before, I didn't remember but proceeded with my data mining.
I noticed various empty weights a given volume, depending on source and material and decided to assemble the various figures shown on your page to sort of have a broader picture.

Whenever I had the need to know about the empty (and filled) weight of a drop tank, if the data was lacking I used to use a very simple (and ... very erroneous) rule : the empty weight of a WWII drop tank was set @ 1 pound for 1 imp.gal. It's crude & wrong but in the absence of information... You will find the application of this weird rule in the below table. The idea was that a value above this silly average should call attention...

What surprised me when reading the various above contributions was the frequent mention of steel tanks. Really ? I thought they generally were made of aluminium (or paper or various composite materials to save this strategically important alloy). Anyway, while my table summary is mainly intended for my own consumption I thought I could share it with you, should anyone be interested. Ah! Don't waste your time telling me my silly rule-of-the-thumb is wrong & silly, because ... I do know it's wrong & silly. The interresting part might be the various weights being assembled in regard of the volumes.

The table reads as follows : 1. volumes at the left on a grey background are (rounded) conversion of the originally publised data (eg: US to imp gal or the other way around) 2. extended series of volumes atop from left to right are expressed in imp.gal

Blessing to all & best regards, Pierre Deveaux, Brussels (Belgium)

 

[MiTasol]

Excellent work and thanks for sharing with all.

All the A6M drop tanks I have seen were aluminium alloy but naturally that does not mean that non-alloy tanks were used on all. And all the Ki-43 tanks I have seen were steel.

 

[PierreDeveaux]

Excellent work and thanks for sharing with all.

All the A6M drop tanks I have seen were aluminium alloy but naturally that does not mean that non-alloy tanks were used on all. And all the Ki-43 tanks I have seen were steel.

Hello MiTasol,
Thanks for your kind words. Steel was the surprise form me. But if some were steel made than in steel they were.

As mentioned elsewhere, I collect data to support a game project, so weight comes into play either to mimic what the reality was or to remain "within reason" when departing from it. Most of the data is found is somewhat "raw format" while I like to be able to wrap the whole in a glance - I mean whenever possible. If that silly table is of any use to anyone, than that was good enough a reason not to trash it. The information harvested here show in more edible manner on my pages All the best, Pierre Deveaux
-

 

[33k in the air]

A timely resurrection of this thread as I've been revisiting the data I have, and have some additions.

First, the technical document posted in post #2, while very useful, is missing some pages, as the page numbers at the bottom of the page jump from 68 to 71. In another thread, I forget which, a different scan of that document was posted. This one included the missing pages as well containing additional pages (73-75). I'll attach the file to this post.

Here are the drop tanks on the missing and extra pages:

165 gallon auxiliary external tank (knockdown)
(not to be confused with the 165 gallon external pressurized tank)
165 USG capacity, 100 lbs empty weight, fiber material, P-38 aircraft

250 gallon auxiliary bomb bay tank
250 USG capacity, 125 lbs empty weight, metal, B-26 aircraft

260 gallon auxiliary bomb bay tank
260 USG capacity, 272 lbs empty weight, non-metallic and self-sealing, B-26 aircraft

400 gallon auxiliary bomb bay tank
400 USG capacity, 365 lbs empty weight, non-metallic and self-sealing, B-24 aircraft


Additional tank data from other sources:

400 gallon auxiliary bomb bay tank
(Lancaster I/III manual, AP 2062A & C, Vol. I, April 1943)
400 ImG / 480 USG capacity, 428 lbs empty weight, Lancaster I/III aircraft

The fully loaded and installed weight of drop tanks of the stated capacity as computed from the aircraft mission weights given in the Airplane Characteristics & Performance publication for that aircraft.

150 USG capacity drop tank
1,075 or 1,025 or 1,023 or 1,022 lbs installed weight
175 or 125 or 123 or 122 lbs empty weight including all fittings, attachments, and braces
F7F-1/1N/2N/3 and F4U-1C/1D aircraft

300 USG capacity drop tank
2,106 or 1,930 or 1,926 lbs installed weight
306 or 130 or 126 lbs empty weight including all fittings, attachments, and braces
F7F-1/1N/2N/3 aircraft

 

[MiTasol]

Thanks 33k in the air for that much better quality and more complete post than what I had.

I am looking for the Ki-43 photos I took some time back and posted on ww2aircraft but so far no luck.

 

[PierreDeveaux]

Thanks 33k in the air for that much better quality and more complete post than what I had.

I am looking for the Ki-43 photos I took some time back and posted on ww2aircraft but so far no luck.

Thanks "33 in the air", sweet of you to offer this update - it's Christmas Day ahead of time. Both these TO.03-1-1946 of yours are saved for future reading and "absorption". Friendly greetings, Pierre Deveaux, Brussels (Belgium)

 

[33k in the air]

Thanks 33k in the air for that much better quality and more complete post than what I had.

I wish I could remember what thread it was posted in so I could properly credit the person who provided it.

 

[33k in the air]

Whenever I had the need to know about the empty (and filled) weight of a drop tank, if the data was lacking I used to use a very simple (and ... very erroneous) rule : the empty weight of a WWII drop tank was set @ 1 pound for 1 imp.gal. It's crude & wrong but in the absence of information... You will find the application of this weird rule in the below table. The idea was that a value above this silly average should call attention...

The simple metric I've settled upon for calculating the empty weight of a drop tank without a known empty weight is the ratio resulting from this formula:

empty weight in pounds divided by the tank capacity in U.S. gallons

For example, a 75 USG capacity tank with an empty weight of 60 lbs would have a ratio of 0.80 (60 lbs/75 USG=0.80). The ratio of course varies by capacity, thickness of construction, and material from which the tank is made. But with enough known data points an average ratio can be determined for use with unknown empty tank weights. American fighter drop tanks mostly range from 0.67 to 0.80. Auxiliary bomb bay tanks tend to be around 0.90, while British slipper tanks have a ratio well above 1.00.

As a quick-and-dirty method of determining the empty tank weight this ratio system works well enough.