Hi, I'll just start by saying sorry that I may be posting this in the wrong area of the forums, but couldn't see anywhere better fitting! If there is, I ask a moderator or admin to kindly move it for me.
As the title suggests, I have a question regarding the length necessary for the divergence part of a nozzle. I'm making a PVC rocket motor, the PVC is 3cm diameter (about 1 1/4 inch). I'm making moulds for concrete using 3cm diameter dowel and my poor man's lathe (a power drill in a bench vice and a wood file). My throat will be about 8mm diameter, but I have no idea how long the divergent cone must be. I'm planning to make it with walls at 15 degrees to the center axis of the motor. At this angle the nozzle would be very long and heavy if the wide end of the cone went all the way to the PVC case, so I just want it to be long enough to do the job of expanding the gasses efficiently. I also wonder if people have tried making motors of this size without a convergent/divergent nozzle, just a straight bored plug, and how badly the performance compares.
If any one has any proven information, or even just suggestions, I'd be very grateful!
Thanks, Steve.
Edit: I've just re-posted this in the 'propulsion' thread. Please delete from here!
As the title suggests, I have a question regarding the length necessary for the divergence part of a nozzle. I'm making a PVC rocket motor, the PVC is 3cm diameter (about 1 1/4 inch). I'm making moulds for concrete using 3cm diameter dowel and my poor man's lathe (a power drill in a bench vice and a wood file). My throat will be about 8mm diameter, but I have no idea how long the divergent cone must be. I'm planning to make it with walls at 15 degrees to the center axis of the motor. At this angle the nozzle would be very long and heavy if the wide end of the cone went all the way to the PVC case, so I just want it to be long enough to do the job of expanding the gasses efficiently. I also wonder if people have tried making motors of this size without a convergent/divergent nozzle, just a straight bored plug, and how badly the performance compares.
If any one has any proven information, or even just suggestions, I'd be very grateful!
Thanks, Steve.
Edit: I've just re-posted this in the 'propulsion' thread. Please delete from here!
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