The Quest for Zip Fuel (boron based fuels)

They sound like something out of a movie villain’s secret rocket base, but exotic and toxic fuels with names like “pentaborane” and “HEF-3” were once the height of cutting-edge Cold War technology.

Of all the sources about such science-fiction stuff, the most entertaining is the one written by a luminary few people have heard of. In his delightful and irreverent memoir Ignition! An Informal History of Liquid Rocket Propellants, rocket chemist John Clark devoted a whole chapter to the quest for boron-based fuels in all their corrosive, explosive glory.

warisboring.com...

Now if someone could only come up with a material unfriendly to boron carbide deposition and a stable boron fuel...

You mean public disclosure of "a material unfriendly to boron carbide deposition and a stable boron fuel". Right?

If boron based fuel ever becomes a reality, would we be able to supply enough of it?

Boron is rare in the Universe and solar system due to trace formation in the Big Bang and in stars. It is formed in minor amounts in cosmic ray spallation nucleosynthesis and may be found uncombined in cosmic dust and meteoroid materials. In the high oxygen environment of Earth, boron is always found fully oxidized to borate. Boron does not appear on Earth in elemental form. Extremely small traces of elemental boron were detected in Lunar regolith[57][58]

Although boron is a relatively rare element in the Earth's crust, representing only 0.001% of the crust mass, it can be highly concentrated by the action of water, in which many borates are soluble. It is found naturally combined in compounds such as borax and boric acid (sometimes found in volcanic spring waters). About a hundred borate minerals are known.

Source WP

Remember the adds for "20 mule team Borax", years ago, but where did it come from?

originally posted by: charlyv
If boron based fuel ever becomes a reality, would we be able to supply enough of it?

Boron is rare in the Universe and solar system due to trace formation in the Big Bang and in stars. It is formed in minor amounts in cosmic ray spallation nucleosynthesis and may be found uncombined in cosmic dust and meteoroid materials. In the high oxygen environment of Earth, boron is always found fully oxidized to borate. Boron does not appear on Earth in elemental form. Extremely small traces of elemental boron were detected in Lunar regolith[57][58]

Although boron is a relatively rare element in the Earth's crust, representing only 0.001% of the crust mass, it can be highly concentrated by the action of water, in which many borates are soluble. It is found naturally combined in compounds such as borax and boric acid (sometimes found in volcanic spring waters). About a hundred borate minerals are known.

Source WP

Remember the adds for "20 mule team Borax", years ago, but where did it come from?

It came from, and still does come from, an area west of Death Valley in CA.

a reply to: anzha

I believe boron was used in the after-burner fuel for the SR-71 / A-12 "Blackbird" if I'm not mistaken.

a reply to: Flyingclaydisk

Triethylborane was used to ignite the JP-7 on engine start. They carried a limited amount in case they needed to restart in flight.

a reply to: Zaphod58

That's right, it was startup, not after burner.

Isn't this in use now on some black projects currently?

Just nod your head if it's true.

So, Zaphod, let me ask a hypothetical question:

From your experience, what would it take to be able to refuel the TEB of a fast mover in flight?

I'm assuming that a hypergol like TEB could not be put through the same plumbing that's used for JP.

a reply to: Zaphod58

a reply to: grey580

If so only to ignite the jp7 (if thats the aircraft what youre referring to ) fuel.

Not responsible for what you think it is..

a reply to: BASSPLYR

ahh alrite..

too bad the valkyrie never got going.

oh and i never saw a pic of the f-108.

neat looking plane mockup.

originally posted by: Flyingclaydisk
a reply to: anzha

I believe boron was used in the after-burner fuel for the SR-71 / A-12 "Blackbird" if I'm not mistaken.

They actually injected cesium aka panther piss into the afterburner plume to help breakup its IR signature

a reply to: 1947boomer

Not wanting to answer for Zaph, my understanding is that the TEB was strictly a ground resupply only thing and the Blackbird family carrier a finite amount on each flight (the total number escapes me but I want to say 50) to deal with unstarts that occurred during flight.

Edit according to wiki 16 was the number of TEB shots

a reply to: 1947boomer

You'd need to flush the boom with something, plumb a separate tank on both tanker and receiver, then flush the boom again after refueling. I'm not sure you could flush it in flight, so you'd have to have a dedicated tanker for it.

The issue with Boron based fuels and one of the reasons they abandoned them was the utter toxicity of them.

The fuel is toxic
the exhaust is toxic
the fuel is really corrosive and had the potential to destroy turbine blades
made the old water injected birds exhaust look downright stealthy

An the toxic issue was based on 50's knowledge which was at best indifferent to hazards. No way it would fly today.

Death Valley was an original site for borax but it died off when it was found in the Mojave. There is an old USAF Base #72 near Boron California where they would have gotten their supply www.airfields-freeman.com...

a reply to: Zaphod58

That's what I thought--a dedicated tanker for zip fuel. That would mean two refueling hookups just before a high speed dash instead of one.

I suggest it should be possible to extend the performance of a turboramjet type engine to higher speeds and altitudes than achievable by the J58 if you're willing and able to burn more TEB in the afterburner section. I suggest you'd have to modify the afterburner section to handle higher temperatures and the abrasive combustion products of TEB (primarily Cubic Boron Nitride particles). I would think that ceramic liners would do the trick.

That means that you'd have to burn an amount of TEB roughly equivalent to the amount of JP, so you'd have to be able to resupply both fuels in flight. The cost would be twice as many tanker hookups per sortie plus the fact that TEB is more expensive than JP. On the other hand, these are both operational costs, not primarily R&D costs.

As I see it, this would be a kind of "brute force" approach to Mach 6 without having to develop an entirely new engine thermodynamic cycle.

Hypothetically, of course.

a reply to: 1947boomer

Not ceramic, but ceramalloy.

a reply to: 1947boomer

Theoretically, they're getting a handle on the TBCC engines. At least they should be by now with all the work they've put into them. If they can make them work reliably, they should be able to hit Mach 6-7, although from what I've heard there's a serious financial plateau.

When talking it over with some people I know, according to their information, Mach 6-6.5 is doable financially. They might even be able to justify 7, but that's getting into some serious numbers. But between 7 and 7.5 it goes from "Ok, this will hurt but it's doable without gutting our budget" to "Well there goes the next three years of our budget, so I hope to hell we can stretch our current fuel levels really far".

a reply to: Zaphod58

Will we ever see the WJ-38 that was made mach 3 capable applied to a tomahawk? There were some exciting things to come out of that NASA TBCC program and to me the modified WJ-38 is one of my favorites. Lots of great stuff out there from NASA to read up on that program.

I think the thing with exotic fuels is that it lengthens the logistical equation. The DoD likes to run everything off as common a fuel as possible. An aircraft sitting as if it were deadlined because of an exotic fuel shortage would be an outrage in a lot of circles.

Fun little wiki: Wiki

a reply to: Caughtlurking

Probably not. I'd love to see a Mach 3 Tomahawk, but they're just not really set up for that kind of speed.