Different iron oxide catalysts

[Apocaloptigon]

So, I know that some iron oxides are better catalysts than others for different fuels, but I'm wondering: which one has the most power? I'm using a

kno3/sugar mix and mainly black iron oxide, but I don't really know if that has an effect compared to red iron oxide.

[stix]

Richard Nakka has some great info on modifiers:

Experiments with Oxides and other possible Burn Rate Modifiers http://www.nakka-rocketry.net/oxidex.html

Also a lot of other useful info for the sugar rocket enthusiast.

 

Cheers.

[PeteyPyro]

That's some interesting research, stix. The brown iron oxide burn rate modifier gave some surprising results. Thanks for posting Richard's tests and results.

[stix]

Not a problem Petey.

 

Richards website was one of the first I came across when I got into sugar rockets. There's a lot of testing that he has already done, so it's always been a good point of reference for me for many years.

[Apocaloptigon]

Thanks. This will help a ton, especially since my shipment of kno3 just got here.

Edit: Hey, now I know that shady russian youtuber was right about yellow iron oxide

Edited November 29, 2017 by Apocaloptigon

[stix]

Yeah, I find it quite ironic in that I'm always trying to "slow" down the burn rate of my fuel - not increase it. Internal burners+RIO = CATO. Others seem to be hell bent on increasing it!!

 

It seem from his tests that the addition of epsom salts, Magnesium Sulfate (MgS) slows the burn rate down. That sounds good. [Note to self] When I get back into making fuels and motors I should try this out.

[NeighborJ]

Stix,I'm surprised to find the magnesium sulfate is listed as a negative catalysts or burn modifier. There are several report compositions out there which list it as the main oxidizer. It is of coarse a high temperature oxidizer and requires a metal fuel to reach those temps, sugar fuel likely won't reach those kinds of temps so it would react as an inert filler material.

[stix]

Stix,I'm surprised to find the magnesium sulfate is listed as a negative catalysts or burn modifier. There are several report compositions out there which list it as the main oxidizer. It is of coarse a high temperature oxidizer and requires a metal fuel to reach those temps, sugar fuel likely won't reach those kinds of temps so it would react as an inert filler material.

 

Thanks for that NJ, my understanding of chemistry is pretty much Nil. One wonders why he bothered with that test.

 

If all it's doing is acting as an inert filler, then I guess that means I'm not going to bother with testing it myself. It would be nice to have a "negative catalysts or burn modifier" that did not reduce the power or specific impulse of the fuel.

[NeighborJ]

Haha, that would be a miracle. The only way that could happen is if you were able to change the BTU or calorie content of the fuel and match the oxidizer content or use a stronger oxidizer all together then add a the appropriate catalyst to carefully match the case pressure.

 

Of coarse there is the option to choose a fuel additive which creates more gas volume then use a negative cat to maintain that original case pressure. It's hard to beat the gas production of sugar.

 

http://www.wichitabuggywhip.com/fireworks/rockets/whistletests.html this site lists a lot of catalysts both negative and positive used on whistle fuel but many will work on sugar fuel.

[stix]

Thanks NJ, Interesting info on that link. Yeah, I thought it would be difficult to slow the burn rate down without sacrificing the Specific Impulse. I think with my propellant, I'll just leave things as they are.

 

Regarding Specific Impulse (I_sp). That article describes specific impulse is calculated as: total impulse divided by the motor weight. This is incorrect. The Specific Impulse is determined as total impulse divided by the propellant weight.

 

In other words, it's important (for some ) to know how efficient the propellant is for its weight. The weight of the motor is irrelevant for this calculation, but important in the end for altitude calculations.

 

I thought it useful to point this out considering that we are discussing burn rate modifiers.

Edited December 3, 2017 by stix