The nozzle
showcased in this example was designed for the PVC
hybrid rocket engine and its parameters are:
Throat
diameter = |
0.43" =
11 mm |
Half
Convergence angle = |
45 deg. |
Half
Divergence angle = |
20 deg. 56 min. |
Expansion
Ratio = |
7.5 |
The engine
and nozzle are made with 1.5" Sch. 40 PVC.
This
is what the ceramic nozzle insert looks like just before its final
assembly.
There
are two tools needed for the molding process:
the convergence molding tool and the throat + divergence molding
tool.
These
molding parts are cast in cardboard or paper cones with fast setting
concrete cement and need to incorporate the design parameters
for the specific nozzle.
The cardboard
cones can be done using Cone
version 1.3 for Windows 95, NT or better, Copyright (c) 1999-2000
J.J.van der Sande.
The convergence
molding tool is basically a 90 deg. cone.
The divergence
+ throat tool in this particular example is a 41 deg. cone with
a 3/8" steel tube centered on its main axis.
There
are lots of clays one can experiment with that would work fine.
The one I have been using is Laguna Modeling Clay
which is a Cone 06 (1830 deg. F). I found a local ceramic shop
that fires them for about 40 cents each.
 
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