David Childers
February 21, 2008
Structures Cost
Center of Mass
•Thanks to John Tsohas for the contacts
•Structures Group for research
AAE 450 Spring 2008
Big Change in Cost
 Previous Cost
Inclusions
•Major Change
•Tank cost
– Sheet Metal Rolling
– Raw Material
– Rivets
• Two Methods:
• ATK Satellite Tanks
• Spincraft
Manufacturing Costs
– Welding
AAE 450 Spring 2008
Structures
2<#>
Test Case: LG-CA-DA-DT (ATK Costs)
Cost Item
Stage 1 (Al)
Stage 2 (Al)
Stage 3 (Ti)
Tanks (Fuel &Ox)
$2.04 million
$690,000
$95,000
Material
$17,100
$820
$1,250
Welding
$8,400
$1,800
$1,750
Rivets
$310
$85
$50
Manufacturing
$29,400
$8,400
$46,200
Stage Sum
$2.09 million
$700,000
$145,000
Total
≈$3 million
Structures Costs Only
Tank Cost Equation:
y = 157169Ln(x) + 714253, where x=volume
AAE 450 Spring 2008
Structures
3<#>
Test Case: LG-CA-DA-DT (Spincraft Costs)
Cost Item
Stage 1 (Al)
Stage 2 (Al)
Stage 3 (Ti)
Material
$17,100
$820
$1,250
Welding
$8,400
$1,800
$1,750
Rivets
$623
$78
$50
Manufacturing
$475,000
$470,000
$948,000
Stage Sum
$502,000
$473,000
$951,000
Total
≈$1.93 million
Structures Costs Only
4<#>
Cost Breakdown
 Welding
– $150/hr
– Times:
• Al=0.6m/hr
• Stl=0.65m/hr
• Ti=0.325m/hr
 Rivets
–
–
–
–
1 rivet/6in (1r/0.152m)
$0.73/rivet
0.049 hr/rivet
$52/hr
Material
Rate:
Al=$13.23/kg (Space grade)
Stl=$0.23/kg
Ti=$88.91/kg
Manufacturing
With ATK Tanks
$70/hr for 5 hrs/sheet
Ti 5.5 times longer than Al or Stl
Performed for:
Nose cone, Skirts, Skin between
tanks
Spincraft
Labor=$150/hr
Al &Stl: 26 wks (40hrs/wk)
Ti: 52 wks
AAE 450 Spring 2008
Structures
5<#>
ATK Tank Costs
Volume (m3) [in3]
Cost ($)
(Existing Tanks)
Tank Shape
0.461 [28100]
600,000
Sphere
0.432 [26350]
400,000
Cylinder w/ Dome
Ends
0.229 [14000]
250,000
Cylinder w/ Dome
Ends
0.059 [3600]
250,000
Sphere
0.015 [890]
60,000
Sphere
Walter Tam, ATK
•Tank Notes
•Composites
•$2 mil for small volume tank & 2 yrs to build
AAE 450 Spring 2008
Structures
6<#>
Tank Costs
•Lower left plot used for cost
determination
$600,000
Tank cost per Volume
700,000
Cost ($)
$400,000
500,000
400,000
Cost ($)
y = 6E+07x3 - 4E+07x2 + 7E+06x - 31462
R² = 1
$500,000
y = 157169ln(x) + 714253
R² = 0.9966
600,000
Tank cost vs Volume
$700,000
$300,000
$200,000
$100,000
300,000
$0
0
200,000
0.1
0.2
0.3
0.4
Volume (m^3)
•Above plot scheme fails due to
dip between 0.15 and 0.4m3
100,000
0
0
0.1
0.2
0.3
0.4
0.5
Volume (m^3)
Plots by David Childers
AAE 450 Spring 2008
Structures
•Cost does not decrease
then increase again
7<#>
0.5
References
 Paul Morissette, Gilchrist Metalfab
 Walter Tam of ATK Space Systems, Inc. (PSI Operations),
http://www.psi-pci.com/.
 Mike Murphy, Spincraft
http://www.spincraft.net/aerospace.htm.
 Mark Sutton, G.E.
 COST CONSIDERATIONS IN USING TITANIUM, GREEN, E. A.,
COULON, J. F. Lockheed-California Company, Burbank, California
v AlAA Paper.
 http://www.metalprices.com/
 TitaniumJoe.com
 Youngstown Tool & Die Co.
 RobotMarketplace.com
AAE 450 Spring 2008
Structures
8<#>