https://www.aircraftspruce.com/catalog/wppages/cascophen.php
https://cpadhesives.com/products/dyn-185-aerodux-resorcinol-resin-kit
Many years ago when I was just starting with APCP I tried several versions of
epoxy plus filler, for small nozzles. Even with high-temperature fillers such
as graphite and magnesium oxide, the throats eroded very rapidly; a 29mm motor
would cease within a second.
The binder seems to be the key. Later I tried DAP Resorcinol glue, which is a
type of phenolic (same as the two above). Nozzles stood up to the temperature
mostly okay, but the glue shrank badly and left cracks, which gave an
interesting exhaust...
Someone previously mentioned DAP Plastic Resin glue as being tolerant of
extreme temperatures. I haven't tried it.
Best -- Terry
________________________________
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> on behalf of
Peter Fairbrother <peter@xxxxxxxxxx>
Sent: Thursday, April 22, 2021 5:05 AM
To: arocket@xxxxxxxxxxxxx <arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: nozzle problem - problem nozzle...
Epoxy melts at surprisingly low temperature. Try phenolic.
Peter Fairbrother
On 22/04/2021 08:16, Hagen Hübner wrote:
Hello everyone,
a few days ago we (Forschungsgemeinschaft Alternative Raumfahrt - FAR
e.V.) tested an O-motor with a nitrate-based fuel. The part of the
nozzle near the combustion chamber was made of graphite and withstood
the high temperatures and the abrasive exhaust without any problems. The
nozzle extension - for weight reasons made of carbon fiber reinforced
epoxy resin (tempered, but otherwise standard resin), material thickness
3 - 7 mm - however, failed after about one second of burning time (see
attached photos).
Question(s): What can be improved to prevent the extension from burning
through in the future?Is there any chance at all chance to make a
weight-saving nozzle extension made of composite, designed for a burn
time of 5 - 10 seconds? Which more temperature-resistant resin should I
use? Which reinforcing fibers are (more) useful? Do basalt fibers have a
significant advantage over carbon fibers?
Regards,
Hagen