A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Technology
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Peroxide biprop ignition



 
 
Thread Tools Display Modes
  #1  
Old December 1st 03, 03:40 PM
Oren Tirosh
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

Some methods I've seen mentioned for peroxide biprop ignition a

Decompose the peroxide with catalyst pack.
Pyrotechnic igniter in the chamber.
Dissolve catalyst in fuel.
Hypergolic starting slug in fuel feed line.

How about mixing some liquid catalyst into the peroxide feed for a few
seconds until there is stable self-sustaining combustion in the
chamber? Liquid catalysts for monoprops have been abandoned in favor
of catalyst packs for good reasons but they seem to have some
desirable properties for biprop ignition:

Usable with high concentration peroxide.
Can be used with strongly stabilized peroxide.
No hazardous materials.
Restartable and reusable.

The catalyst is mixed into the peroxide just before injection into the
chamber. This cannot be done safely with a fuel but catalytic
decomposition is slow enought to give some time for mixing. The
injector is optimized for operation with uncatalysed peroxide. It may
not perform optimally with the mixed-phase decomposing peroxide; it
just needs to be good enough for the ignition phase. The injector and
mixing chamber are flushed of any residues by ample amounts of
peroxide (except on some emergency shutdowns) so the catalyst should
not contaminate the upstream oxidizer lines .

Oren
  #2  
Old December 5th 03, 08:01 PM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

In article ,
Oren Tirosh wrote:
How about mixing some liquid catalyst into the peroxide feed for a few
seconds until there is stable self-sustaining combustion in the
chamber?


This is a minor variant of the "hypergolic starting slug" approach.

No hazardous materials.


Depends on what catalyst you're using. Even permanganates are not exactly
mother's milk, and things like TEA are definitely hazardous.

Restartable and reusable.


Subject to the need for yet another fluid system, with the added
complexity that entails.

The catalyst is mixed into the peroxide just before injection into the
chamber. This cannot be done safely with a fuel but catalytic
decomposition is slow enought to give some time for mixing.


I have real doubts about that part of the idea. Catalystic decomposition
will not be slow with high-concentration peroxide and an effective liquid
catalyst mixed well together. Mixing *in* the chamber sounds both better
and safer.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #3  
Old December 5th 03, 08:01 PM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

In article ,
Oren Tirosh wrote:
How about mixing some liquid catalyst into the peroxide feed for a few
seconds until there is stable self-sustaining combustion in the
chamber?


This is a minor variant of the "hypergolic starting slug" approach.

No hazardous materials.


Depends on what catalyst you're using. Even permanganates are not exactly
mother's milk, and things like TEA are definitely hazardous.

Restartable and reusable.


Subject to the need for yet another fluid system, with the added
complexity that entails.

The catalyst is mixed into the peroxide just before injection into the
chamber. This cannot be done safely with a fuel but catalytic
decomposition is slow enought to give some time for mixing.


I have real doubts about that part of the idea. Catalystic decomposition
will not be slow with high-concentration peroxide and an effective liquid
catalyst mixed well together. Mixing *in* the chamber sounds both better
and safer.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #4  
Old December 5th 03, 11:51 PM
John Carmack
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

(Oren Tirosh) wrote in message . com...
Some methods I've seen mentioned for peroxide biprop ignition a

Decompose the peroxide with catalyst pack.
Pyrotechnic igniter in the chamber.
Dissolve catalyst in fuel.
Hypergolic starting slug in fuel feed line.

How about mixing some liquid catalyst into the peroxide feed for a few
seconds until there is stable self-sustaining combustion in the
chamber? Liquid catalysts for monoprops have been abandoned in favor
of catalyst packs for good reasons but they seem to have some
desirable properties for biprop ignition:

Usable with high concentration peroxide.
Can be used with strongly stabilized peroxide.
No hazardous materials.
Restartable and reusable.


It could probably work, but I think you overstate the case for it.

Various platinum based catalysts will work fine with 98% peroxide, it
is only the classic silver ones that have issues. The commercial
catalysts we are using for our mixed-monoprop engines would work fine
with 98%, for instance.

High concentration and highly stabilized is really only a condition
that happens at the amateur experimental stage where people are
concentrating cheap peroxide on bench level equipment in small
batches. Anything resembling a commercial rocket is almost certainly
going to be using unstabilized peroxide.

Adding a third consumable and the associated plumbing is a non-trivial
increase in system complexity.

We have only done a few tests with liquid catalysts, but we have had
much better success with solid catalyst packs. Compared to almost any
other biprop, cat-pack decomposition auto-ignition biprops are really
easy to make work at good efficiencies.

John Carmack
www.armadilloaerospace.com
  #5  
Old December 5th 03, 11:51 PM
John Carmack
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

(Oren Tirosh) wrote in message . com...
Some methods I've seen mentioned for peroxide biprop ignition a

Decompose the peroxide with catalyst pack.
Pyrotechnic igniter in the chamber.
Dissolve catalyst in fuel.
Hypergolic starting slug in fuel feed line.

How about mixing some liquid catalyst into the peroxide feed for a few
seconds until there is stable self-sustaining combustion in the
chamber? Liquid catalysts for monoprops have been abandoned in favor
of catalyst packs for good reasons but they seem to have some
desirable properties for biprop ignition:

Usable with high concentration peroxide.
Can be used with strongly stabilized peroxide.
No hazardous materials.
Restartable and reusable.


It could probably work, but I think you overstate the case for it.

Various platinum based catalysts will work fine with 98% peroxide, it
is only the classic silver ones that have issues. The commercial
catalysts we are using for our mixed-monoprop engines would work fine
with 98%, for instance.

High concentration and highly stabilized is really only a condition
that happens at the amateur experimental stage where people are
concentrating cheap peroxide on bench level equipment in small
batches. Anything resembling a commercial rocket is almost certainly
going to be using unstabilized peroxide.

Adding a third consumable and the associated plumbing is a non-trivial
increase in system complexity.

We have only done a few tests with liquid catalysts, but we have had
much better success with solid catalyst packs. Compared to almost any
other biprop, cat-pack decomposition auto-ignition biprops are really
easy to make work at good efficiencies.

John Carmack
www.armadilloaerospace.com
  #8  
Old December 6th 03, 04:47 AM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

In article ,
Derek Lyons wrote:
High concentration and highly stabilized is really only a condition
that happens at the amateur experimental stage where people are
concentrating cheap peroxide on bench level equipment in small
batches. Anything resembling a commercial rocket is almost certainly
going to be using unstabilized peroxide.


Why is this so may I ask?


A commercial rocket is going to be using peroxide in sufficient quantity
to get reasonable cooperation from peroxide suppliers (from new ones
created to serve it, if not from existing ones). So it will have access
to high-concentration peroxide that is either unstabilized or, at worst,
lightly stabilized.

Whereas amateurs have to work with existing peroxide suppliers, who are
unhelpful (to put it mildly). So they are likely to have to do their own
concentrating, and most of the easy bench-scale processes concentrate
stabilizers as well as peroxide.

Back when Beal was a going concern, buying high-concentration unstabilized
peroxide in quantity and gearing up to buy it in QUANTITY, for a little
while amateurs could piggyback on that new peroxide infrastructure and buy
small amounts of rocket-grade peroxide without much difficulty. Not any
more, as John can tell you at some length.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #9  
Old December 6th 03, 04:47 AM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

In article ,
Derek Lyons wrote:
High concentration and highly stabilized is really only a condition
that happens at the amateur experimental stage where people are
concentrating cheap peroxide on bench level equipment in small
batches. Anything resembling a commercial rocket is almost certainly
going to be using unstabilized peroxide.


Why is this so may I ask?


A commercial rocket is going to be using peroxide in sufficient quantity
to get reasonable cooperation from peroxide suppliers (from new ones
created to serve it, if not from existing ones). So it will have access
to high-concentration peroxide that is either unstabilized or, at worst,
lightly stabilized.

Whereas amateurs have to work with existing peroxide suppliers, who are
unhelpful (to put it mildly). So they are likely to have to do their own
concentrating, and most of the easy bench-scale processes concentrate
stabilizers as well as peroxide.

Back when Beal was a going concern, buying high-concentration unstabilized
peroxide in quantity and gearing up to buy it in QUANTITY, for a little
while amateurs could piggyback on that new peroxide infrastructure and buy
small amounts of rocket-grade peroxide without much difficulty. Not any
more, as John can tell you at some length.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #10  
Old December 6th 03, 12:20 PM
Oren Tirosh
external usenet poster
 
Posts: n/a
Default Peroxide biprop ignition

Thanks Henry, John.

All else being equal, would you not prefer your 98% peroxide
stabilized? After all, stabilizers are not added by manufacturers to
make life harder for rocket builders. They are supposed to make
peroxide safer. You've explained why all else is not exactly equal but
the bottom line is a tradeoff between complexity perceived safety.
Such perceptions are not an exact science and are liable to change
quickly on certain circumstances.

Oren
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cheap, easy to handle fuels/oxidizers Earl Colby Pottinger Technology 41 December 23rd 03 02:04 AM
OSP: reliability and survivability Edwin Kite Space Science Misc 77 September 26th 03 06:36 AM
Recommended TSTO technical papers? WvB Technology 14 September 4th 03 06:00 AM
Concentrating hydrogen peroxide Earl Colby Pottinger Technology 1 July 28th 03 07:59 AM


All times are GMT +1. The time now is 02:54 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.