Old Russian Liquid Fuel Rocket Engine - Complete

[G_T]

The tribrid used hybrid startup for a fraction of a second to avoid hard start issues. It started as a hybrid with ABS plastic fuel IIRC, then alcohol flow started. The increased heat melted and blew out the remainder of the ABS and the rest of the burn was liquid. The hybrid mode was just for startup.

Liquid motor starting sequence can be more complex than is the case for solids, or hybrids. Using hybrid startup was a good idea. It provided a softer startup, and at the same time still produced somewhere near full thrust.

Gerald

 

[cls]

I think I remember the tribrids didn't really burn much of the carbon donor (ABS or acrylic or ?).

 

[Pooklord]

I did a little more research and found that yes, it was used as the sustainer stage in the S-75 surface to air missile. Below are the fuels and oxidizers used. Max burn time was 55 seconds.

Fuel: Tonka (TG-02) aka R-Stoff ( 50% triethylamine and 50% xylidine )

Oxidizer: AK-20K aka RFNA (Red Fuming Nitric Acid) (80% nitric acid (HNO3), 20% N2O4 + fluorine-based inhibitor)

I wonder if it could be reconfigured to utilize other fuels/oxidizers?

I hear fluorine is fun stuff -- easy to handle right? Just store it in the fridge in some old container, I guess.

 

[G_T]

Hydrofluoric acid in these oxidizers is there in small percentage, to passivate the vessel so the predominant acid doesn't eat it up. It reacts with the vessel, forming a surface which is much less reactive to the nitric acid. That allows one to get away with certain stainless steel (304L or 4% silicon stainless) or aluminum for the tank.

Early on, there weren't a lot of good options for storing this excellent oxidizer.

Nowdays we might have some plastics (teflon for instance) which could potentially be used for the tank, and could even be used as a coating on what would otherwise be unsuitable tank material. That would alleviate the need for passivation.

I do not know what was used for the tanks in these missiles. I haven't tried to find the info; sorry!

Anyone, feel free to correct any errors in the above.

I've made hydrofluoric acid, years ago. I needed it to etch some silicon wafers before doping them for solar cells. One does take a certain care with chemicals such as this. That went along with asbestos lining the furnace for the doping operations. Times have changed.

Gerald

 

[ksaves2]

I hear fluorine is fun stuff -- easy to handle right? Just store it in the fridge in some old container, I guess.

You are a funny, facetious "bastid". I know that you are "in the know" and laughed out loud with your comment.
Fluorine? The gubbermint guys went there but it's pretty dangerous to deal with. I think they learned the hard way. Kurt

 

[OverTheTop]

You have all read "Ignition!" right?

If not, search for "Ignition free pdf". An entertaining read. I liked it so much I have the hardcover.

 

[techrat]

You have all read "Ignition!" right?

Not yet, but it's now on my kindle and my tablet and on my "to be read" list...

 

[ksaves2]

You have all read "Ignition!" right?

If not, search for "Ignition free pdf". An entertaining read. I liked it so much I have the hardcover.

Oh shoot! When my daughter was in college, I had her order a hardcover copy from the University of Illinois bookstore! There were still some left of a later printing. Great read! Kurt Savegnago

 

[Pooklord]

You are a funny, facetious "bastid". I know that you are "in the know" and laughed out loud with your comment.
Fluorine? The gubbermint guys went there but it's pretty dangerous to deal with. I think they learned the hard way. Kurt

Heh. Well, I HOPE everyone realizes I was trying to be funny here.
Seriously though, F is incredibly dangerous and freakishly reactive to just about everything. It cannot be handled without special equipment.

 

[bad_idea]

You have all read "Ignition!" right?

If not, search for "Ignition free pdf". An entertaining read. I liked it so much I have the hardcover.

It's an incredible read for nearly any rocketry- or physics- or chemistry-inclined reader. I monopolized the sole paper copy of my then-1-million-ish-population city's central library for some considerable time in the early '00s, though all these years later the fine points of the chemistry are escaping me. The major points with respect to rockets and - more importantly - the abiding good humor of Dr. Clarke and his memorable tales of liquids-development history - never fade.