[AR] Re: "Direct" Hydrogen Peroxide engines
- From: "John Dom" <johndom@xxxxxxxxx>
- To: <arocket@xxxxxxxxxxxxx>
- Date: Sun, 18 Sep 2016 22:03:47 +0200
Henry Spencer wrote on 180916:
Really high test peroxide is slightly above the melting point of silver,
in fact, and even lower grades can be close enough to have problems.
I reckon it is more precise to simply mention the wt.-% of HP. The British
"HTP" was usually around 83-85 % HP like used in Black Knight, Black Arrow
and Blue Steel bipropellant engines. Black Arrow's screens would have been
destroyed using 90 % HP and therefore can hardly be named HTP.
Less well known is the HP decomposition temperature can be predicted using
some of the graphs of Hellmuth Walter, the Nazi WWII HP guru (rare early
fifties paperclip debriefing papers). They tell us what final temperature
range to expect at a given HP feed concentration, pack internal pressure and
initial HP feed temperature. The atmospheric melting points of pure silver
and probably all pure metal catalyst screens in a cat pack is not so
relevant since they are lowered *significantly* by the hot oxygen gas (from
the decomposition reaction) in the pack. That oxygen penetrates the screen
metal, lowering its melting point. This came as a surprise. Since then many
papers exist on that subject, mostly research from the fifties and sixties
and probably from later on too (references anybody?). Later, like said,
screen alloys were invented which could be used even with HP 98 % without
melting.
jd
Other related posts:
