arla-lt2.htm Tri-Mode ARLA

Amateur Rocket Launch Assist (ARLA)

Additional Notes on Launch Tubes, Part 2

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Valves

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If a combustor is used as the launch tube gas generator one way of controlling the flame is to use a screen. When both the fuel and oxidizer are gasses they can be blown into a mixing chamber which has a screen a little ways downstream. If built right, the mixture can be ignited downstream of the screen without the flame getting near the injectors.

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Properties of some tubes I've found

Material   Diameter   Pressure    Cost    Notes
  Used        in        psi      per ft

                  Rain for Rent
Aluminum      12        180       $16    Irrigation Pipe, (1)
              10        190
               8        225         8    (2)
               6        300
               4        400
               3        500
(1) May be rented for the first month at $2.02/ft.  Each 
    additional month for $1.01/ft. (Rain for Rent)
(2) May be rented for the first month at $0.90/ft.  Each 
    additional month for $0.45/ft. (Rain for Rent)
    Prices includes Victaulic couplings.

         Denver International Steel and Pipe Supply Co
                http://www.disps.com/pipe5.htm
Stainless     24 OD x 0.500 wall - $31.50/ft
Steel          8 OD x 0.105 wall -  4.25
               6 OD x 0.134 wall -  3.95
               8 5/8 x 0.172 used-  1.95
              36 OD x 0.625 wall - 59.95  Coated
Aluminum       4 1/2 x 0.500     - 15.50  Drill Pipe


                 Desert Industrial Supply
ABS            8                    8.03
Steel          8      3,200        10.66  Regular
               8                   16.25  Seamless
Butterfly Valve, 8 in             350     guess

                      Endura Steel
Steel          8 (0.134 wall)      $9.45  Guage Pipe
               8                   18.50  Seamless .134 wall

                       Other
Valves        12                 $1,000-1,400
               8                    800-1,000

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Thermoplastic Parts, Specs, and Costs

            PVC - Schedule 40

TUBES (Pipes)

Dia     OD     ID   Wall  Pressure  Threaded  Collapse  Cost
in      in     in    in     psi        psi       psi    $/ft

1     1.315  1.033  0.133   450
2     2.375  2.049  0.154   280                         0.45
3     3.500  3.042  0.216   260
4     4.500  3.998  0.237   220
6     6.625  6.021  0.280   180
8     8.625  7.943  0.322   160
10   10.750  9.976  0.365   140
12   12.750 11.890  0.406   130
24   24.000 22.544  0.687   120
36

Note: Different MFGs have the same ODs and pressure ratings 
      but can vary IDs and wall thicknesses to account for 
      variations in materials.

1 in. Inline Splice     $ 0.76
1 in. T                   1.39
1 in. End Cap             0.89
2 in. Ball Valve         12.99
2 in. Union               7.99
2 in. Elbow               1.29
2 in. T                   1.39
2 in. Male Adaptor        1.29

            PVC - Schedule 80

Dia    OD     ID   Wall  Pressure  Threaded  Collapse  Cost/ft
in     in     in    in     psi        psi       psi        $

1    1.315  0.840  0.147   630        320       540
2    2.375  1.881  0.218   400        200       190
3    3.500  2.820  0.300   370        190       155
4    4.500  3.737  0.337   320        160       115
6    6.625  5.646  0.432   280         NR        80
8    8.625  7.490  0.500   250
10  10.750  9.407  0.593   230
12  12.750 11.197  0.687   230
24  24.000 21.418  1.218   210
36

NR = Not Recommended

            PVC - Schedule 120

Dia    OD     ID   Wall  Pressure  Threaded  Collapse  Cost/ft
in     in     in    in     psi        psi       psi        $

1    1.315  0.891  0.200  720
2    2.375  1.845  0.250  470
3    3.500  2.758  0.350  440
4    4.500  3.572  0.437  430
6    6.625  5.434  0.562  370
8
10
12
24
36

            ABS - Schedule 40

Dia     OD     ID   Wall  Pressure  Threaded  Collapse  Cost
in      in     in    in     psi        psi       psi    $/ft

1    
2                                                       0.56
3                                                       1.01
4                                                       1.65
6
8
10
12
24
36

3 in. Female Adaptor  $2.79
3 in. Plug             3.19
4 in. Female Adaptor   3.99
4 in. Plug             2.30
4 in. Elbow, 90 deg    4.99
4 in. Elbow, Long      8.99

            ABS - Schedule 80

Dia     OD     ID   Wall  Pressure  Threaded  Collapse  Cost
in      in     in    in     psi        psi       psi    $/ft

1    
2
3
4
6
8
10
12
24
36


            ABS - Schedule 120

Dia     OD     ID   Wall  Pressure  Threaded  Collapse  Cost
in      in     in    in     psi        psi       psi    $/ft

1    
2
3
4
6
8
10
12
24
36

TEMPERATURE DERATING for PVC

  F    Factor

 73     1.00
 80     0.88
 90     0.75
100     0.62
110     0.50
120     0.40
130     0.30
140     0.22
150   Not Recommended

THREADED FITTING DERATING FOR PVC

Derate by 0.50

VALVES

PVC Ball Valves, 2-4 in.
  Pressure Rated for Continuous Use at 150 psi
Matco B3 8 in valve   $260-280


OTHER NOTES

        Water Tank
Max working pressure = 150 psi
Proof tested = 300 psi

2 in. Steel, Galvanized Nipple, 4 in.  $ 2.29
Double Wall Vent, Galvanized, 24 in.    10
  4 in. outside, 3 in. inside

Pumice Block, 3.25 x 3.25 x 8 in.    $ 5.79
Synthetic 4 x 4 x 8 in.                1.97



This Page Last Updated 13 Dec 98