Eleven Fuel Tanks!

 

Table 1 shows the fuel tank capacities of the Altair in U.S. gallons (U.S.G.) and Imperial gallons (I.G.) This information was derived from various sources as listed below. The table also shows the weight of fuel for each individual tank in pounds (LBS) .

 

TABLE 1
U.S.G.
I. G.
LBS
SOURCE
1 Main Fuselage Tank
240
200
1440
A
4 Standard Wing Tanks
124
103
744
B
1 Extra Fuselage Tank
110
92
660
C
2 Extra Wing Tanks (ea 16 US)
32
27
192
D
2 Wackett Wing Tanks (See Note 3)
91
76
546
E
1 Wackett Fuselage Tank (See Note 3)
24
20
144
E
TOTAL:
621
518
3726
.

 

 

Table 2 is based on the following drawing which appeared in "The Courier-Mail", published in Brisbane on 26th October 1934. The caption states that the drawing is based on information supplied by Sir Charles Kingsford Smith. It will be noted that the tank capacities are very similar to those shown in Table 1.




(Click on image for a larger view)

 

TABLE 2
U.S.G.
I.G.
LBS
SOURCE
1 Main Fuselage Tank
250
208
1500
F
4 Standard Wing Tanks (ea 23 imp)
110
92
660
F
1 Extra Fuselage Tank
109
91
654
F
2 Extra Wing Tanks (ea 12 imp)
29
24
174
F
2 Wackett Wing Tanks (See Note 3)
84
70
504
F
1 Wackett Fuselage Tank (See Note 3)
36
30
216
F
TOTAL:
618
515
3708
.

 

SOURCES
A
P.G. Taylor "Pacific Flight" p. 226
B
J.P. Juptner "U.S. Civil Aircraft"
C
Lockheed Engineering Change Order #371 dated 22MAY34
D
Lockheed Engineering Change Order #372 dated 23MAY34
E
Transcript of lecture by Sir Lawrence Wackett, Sept 1974
F
Drawing of the Altair fuel tanks based on information provided by Smithy and published in "The Courier-Mail", Brisbane 26OCT34.

 

NOTES
1
To convert Imperial to U.S. gallons, multiply by 1.2
To convert U.S. to Imperial gallons, multiply by 0.8327
2
One U.S. gallon of gasoline weighs 6 pounds
3

Smithy and P.G. Taylor both claim that Wackett added only two (2) extra wing tanks, whereas Wackett himself later claimed , in a 1974 lecture, that he added four (4). It is believed that this recollection was incorrect. However, all three basically agree on the total capacities of the extra tanks. It should be noted that the two Wackett wing tanks were removed by Lockheed after the Pacific flight although the Wackett fuselage tank under the pilot's seat was retained. (See "How Many Wackett Tanks?" below)

4
Figures in bold type are primary data. Corresponding figures are conversions

 

How Many Wackett Tanks?

Although most sources state that Wackett added three tanks to the Altair (2 wing, 1 fuselage), Sir Lawrence Wackett himself later claimed to have added five tanks (4 wing, 1 fuselage). The following message, sent in response to a request from the Controller of Civil Aviation, by the District Superintendent of Civil Aviation at Mascot (Sydney) on 10th October 1934, provides another perspective:

" IMPORTANT Your 1453/9. USB full details one additional fuel tank forty gallons capacity being installed each wing. Tanks centre line located 12 feet from centre line aircraft. These tanks mounted in metal straps and felt attached to spar webs similar to D.H. 80. Fuel leads connect with adjacent wing case. One extra tank 24 gallons being installed under front pilot seat final mounting and fuel connection not yet decided. Additional weight of tankage 62 pounds, fuel 760 pounds, this increases tare to 3737 pounds Total fuel 3817 pounds. All up load 7522 pounds."

(Source: National Archives of Australia Series: MP 113/1 Item: VH/USB PT 3)

Considering that this message was sent within a day or so of a first hand observation (of 2 wing tanks), it must be given greater credence than Sir Lawrence Wackett's recollection (of 4 wing tanks) forty years after the event! However, it should be noted that there is an apparent error in DSCA's addition and he has also failed to allow for the weight of crew, equipment, radio and oil as stated on the Australian CofA. Furthermore, it will be noted that the stated capacities of the added tanks are at variance with those derived from other sources. This raises the question of whether or not Wackett and/or Smithy were forthcoming with accurate capacities or if the DSCA estimated the capacities of the three added tanks. Whilst we may never have a definitive answer, it can be seen from the following table that the maximum variance in the total capacity of the three Wackett tanks is only a mere 8 gallons.

 

Imperial Gallons
Wackett
Taylor
Smithy
DSCA
Wing Tanks
76
76
70
80
Fuselage Tank
20
20
30
24
Total
96
96
100
104

 

The DSCA's Weight Calculations

As there are several anomalies with the weight calculations in the DSCA's message, we need to examine these. As mentioned previously, in addition to an apparent arithmetical error, no provision has been made for crew, equipment, radio and oil.

 

3675
Empty Weight (from Aust CofA)
62
Weight of Extra Tanks
3737
Amended Empty Weight
3817
Total Fuel
7554
Gross Weight (DSCA shows this total as 7522 lbs.)

 

By adding the weight of crew, equipment, radio and oil (from the CofA) and by reducing the total fuel to 3708 lbs as calculated in Table 2, we arrive at the following:

 

3675
Empty Weight (from Aust CofA)
62
Weight of Extra Tanks
3737
Amended Empty Weight
340
Crew (from Aust CofA)
20
Equipment (from Aust CofA)
46
Radio (from Aust CofA)
249
Oil (from Aust CofA)
3708
Total Fuel (from Table 2)
8100
Gross Weight (lbs)

 

Again, we may never have a definitive answer, but the preceeding figures suggest that the Altair, in its Pacific flight configuration, may have been significantly heavier than estimated by the DSCA.

 

Issue Date Remarks
3 03JAN01
Added information regarding removal of Wackett wing tanks.



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