My green lady

a reply to: Darkpr0

reliable ignition methods for scramjets? like microwave & e beam controlled ignition? like microwave enhanced flame propagation and microwave driven flame speed enhancement?
resonant cavity co burners n all?

might work well with hydrocarbons (jp7) and boranes.

scramjets are cool but I say why not augmented
energy bypass instead? way less mass than combined cycle turbines/scramjets.

originally posted by: NewsWorthy
Also I should mention that I was lucky enough to FIRST HAND WITNESS a vehicle that was soooo far beyond anything I could imagine, it made me FIRMLY believe in Extraterrestrials.

Don't underestimate people, and what they can imagine.

If we ever meet E.T., we might be going there first.

From what Ive gathered the Lady is more Xb70 ish size..

originally posted by: BASSPLYR
a reply to: Darkpr0

reliable ignition methods for scramjets? like microwave & e beam controlled ignition? like microwave enhanced flame propagation and microwave driven flame speed enhancement?
resonant cavity co burners n all?

If we assume all the above will do the function properly (I have no idea whether they will, I have no data on the above but let's assume it anyway) you still need to provide infrastructure to do so. You would need to provide all the necessary hardware for all of the above, be it microwave production and control, or electron beam, or what have you. All the stuff takes up space, has weight, and costs money. Selling that to a government project leader, even a black project, is difficult. If you could take something that was already done (TEB injection), is familiar to engineers who have been involved, requires well-understood and available infrastructure, you will have a very easy time getting internal support. Now the compound may not necessarily be TEB, as organic chem has improved considerably in the many years which have passed, but the fact that the flame is green suggests (but does not PROVE) boron.

In fact, my whole argument doesn't prove anything. I'm just pointing out a bunch of engineering conveniences which could indicate a developmental path-of-least-resistance.

Edit: Also keep in mind that any ignition methods in an engine will also have to withstand the rigors of nearby combustion. A valve and a port to inject substance is pretty Mickey Mouse stuff. Building other stuff with experimental technology that can also continue functioning across the range of engine operating temperatures is difficult, though I must stress, not impossible.

originally posted by: mbkennel

originally posted by: NewsWorthy
Also I should mention that I was lucky enough to FIRST HAND WITNESS a vehicle that was soooo far beyond anything I could imagine, it made me FIRMLY believe in Extraterrestrials.

Don't underestimate people, and what they can imagine.

If we ever meet E.T., we might be going there first.

Such as our lovely black doritos. mmmm tasty.

originally posted by: mbkennel

originally posted by: NewsWorthy
Also I should mention that I was lucky enough to FIRST HAND WITNESS a vehicle that was soooo far beyond anything I could imagine, it made me FIRMLY believe in Extraterrestrials.

Don't underestimate people, and what they can imagine.

If we ever meet E.T., we might be going there first.

If that was "Ours" then we probably are already there, at least in Drone Capacity. Because I'm not convinced a human can survive that sorta acceleration/stopping in an instant. But if we have come that far then we can probably figure out the method to surviving the flight as well. we're pretty amazing in our ingenuity...

I thought it was JP-7.

Not JP-6.

originally posted by: yuppa

originally posted by: mbkennel

originally posted by: NewsWorthy
Also I should mention that I was lucky enough to FIRST HAND WITNESS a vehicle that was soooo far beyond anything I could imagine, it made me FIRMLY believe in Extraterrestrials.

Don't underestimate people, and what they can imagine.

If we ever meet E.T., we might be going there first.

Such as our lovely black doritos. mmmm tasty.

Somewhere in here is a Nacho-Cheese joke.

But it went black.

Do you think of a twin engine configuration or four engine on the green girl ?

originally posted by: Darkpr0

originally posted by: pteridine
Boron compounds [boranes and carboranes] burn with a green flame. The low mass of the Boron atom and the high energy of combustion would give a rocket engine a high specific impulse if a suitable boron based fuel could be developed. Boron containing compounds are not suitable for use in jet engines because when they burn, they produce boron oxides which abrade the turbine blades in seconds...literally.

Two points.

#1 is that the green flame is not limited to boranes, but boride ions. This includes, but is not limited to, boranes. So the amount of compounds that are included grows considerably.

#2 is that if you are afraid of turbine blades being abraded, then you would inject it after the turbines. Placing such a compound in the afterburner would also result in us seeing the green flame rather than it being swallowed up in the internals of the engine.

I was having a good think about various engines. Two things occurred to me. One of the problems with scramjets is that nothing in the air propagates forward. This is a fundamental idea in supersonic flow, and it is a very important concept. It's why shockwaves form, and various other familiar phenomena. But what's important is that if things can't flow forward in a supersonic flow, then maintaining a flame in one spot like a conventional jet is quite difficult because it tends to blow straight out the back of the engine. So one of the big challenges in making engines with faster flow velocities through the core is maintaining reliable ignition of your fuel. Thing two that occurred to me is that TEB lights on contact with air, giving very reliable ignition. This seems oddly convenient.

What boride did you have in mind? All boron compounds would combust to boron oxides. Injecting in the afterburner would eliminate the problems with turbine blades but logistically you would need a separate fuel tank and injection system. The question is whether its performance would make the additional complexity worth the effort.

originally posted by: pteridine

What boride did you have in mind? All boron compounds would combust to boron oxides. Injecting in the afterburner would eliminate the problems with turbine blades but logistically you would need a separate fuel tank and injection system. The question is whether its performance would make the additional complexity worth the effort.

I have no particular borides in mind. Only that the green flame is an indication that boron may be used, and while TEB is the obvious suspect, they've had a long time to rethink the substance in use. It may not even be boron, there are other ions that would produce a flame we describe as green. Why we would use them I can't say, but I'm just trying to make sure that what we think we know isn't overspecific relative to the evidence we actually have on hand.

Also, I'm not sure if you would need a separate fuel tank. You could try using it as a fuel additive. It's true TEB combusts on contact with air, but then all you would need to do is keep it from contacting air. As foolish as this sounds, you could actually pull this off. Purging and pressurizing fuel tanks with inert gas would be a start. But if you could get the logistics to work out, you would potentially have a self-igniting fuel, no need for ignition systems. This can be pretty attractive because not only could you remove the ignition system and all the challenges it poses, but you may also remove some of the restrictions that your ignition system of choice imposes. Wouldn't want to have to deal with a fuel spill, but the same problem would befall an SR-71 TEB leak. We pull the same trick between a gasoline engine and a diesel engine. Diesel engines don't need spark plugs, distributors, coils... Granted it comes with other challenges but there's a certain appeal to using clever design of your fuel to simplify the system needed to wrangle it.

originally posted by: Darkpr0

originally posted by: pteridine

What boride did you have in mind? All boron compounds would combust to boron oxides. Injecting in the afterburner would eliminate the problems with turbine blades but logistically you would need a separate fuel tank and injection system. The question is whether its performance would make the additional complexity worth the effort.

I have no particular borides in mind. Only that the green flame is an indication that boron may be used, and while TEB is the obvious suspect, they've had a long time to rethink the substance in use. It may not even be boron, there are other ions that would produce a flame we describe as green. Why we would use them I can't say, but I'm just trying to make sure that what we think we know isn't overspecific relative to the evidence we actually have on hand.

Also, I'm not sure if you would need a separate fuel tank. You could try using it as a fuel additive. It's true TEB combusts on contact with air, but then all you would need to do is keep it from contacting air. As foolish as this sounds, you could actually pull this off. Purging and pressurizing fuel tanks with inert gas would be a start. But if you could get the logistics to work out, you would potentially have a self-igniting fuel, no need for ignition systems. This can be pretty attractive because not only could you remove the ignition system and all the challenges it poses, but you may also remove some of the restrictions that your ignition system of choice imposes. Wouldn't want to have to deal with a fuel spill, but the same problem would befall an SR-71 TEB leak. We pull the same trick between a gasoline engine and a diesel engine. Diesel engines don't need spark plugs, distributors, coils... Granted it comes with other challenges but there's a certain appeal to using clever design of your fuel to simplify the system needed to wrangle it.

Borides are usually inorganic abrasives. There are some solid-phase, high-energy lithium borides but these would be used in rocket engines. You would need separate fuel tanks because none of the borane/carborane can go through the turbine engines without destroying them. This means that afterburner fuel must be kept separate from other fuel. How boron oxides affect the afterburner mechanics is not known. The advantage of boron is its low mass. Other elements which burn with a green flame have no known advantages in fuels other than some producing toxic exhaust particles. en.wikipedia.org...

a reply to: pteridine

What if they developed a synthetic boron fuel without the abrasive properties?

originally posted by: yuppa
a reply to: pteridine

What if they developed a synthetic boron fuel without the abrasive properties?

The problem is that when any fuel containing boron is combusted, boron oxides result. It is not the fuel creating the problem, it is the "ash," so to speak.

originally posted by: pteridine

originally posted by: yuppa
a reply to: pteridine

What if they developed a synthetic boron fuel without the abrasive properties?

The problem is that when any fuel containing boron is combusted, boron oxides result. It is not the fuel creating the problem, it is the "ash," so to speak.

Not possible to develop ash free boron in a synthetic form? something that burns 100 percent.

originally posted by: yuppa
Not possible to develop ash free boron in a synthetic form? something that burns 100 percent.

He tried to simplify it. Boron oxides are a necessary part of burning boron. They're not ashes in that they're leftovers from incomplete combustion, they're actually products of the reaction. Not something that you can make go away.

originally posted by: Darkpr0

originally posted by: yuppa
Not possible to develop ash free boron in a synthetic form? something that burns 100 percent.

He tried to simplify it. Boron oxides are a necessary part of burning boron. They're not ashes in that they're leftovers from incomplete combustion, they're actually products of the reaction. Not something that you can make go away.

Ahh ok. Hmm what about developing turbine blades that resist its build up then?

originally posted by: yuppa
Ahh ok. Hmm what about developing turbine blades that resist its build up then?

Not buildup, abrasion. The product that gets formed by the reaction is a solid, like sand. It's very hard, much more so than any metal we have. Running the engine on large amounts of it would slowly sandblast the inside of the engine. You could do some crazy stuff like coating the vulnerable parts with ceramic to extend their lifetimes, but this gets astronomically expensive. the TEB (assuming this is what it is) could not be a major constituent of the aircraft's fuel. It would only be an additive, probably solely for even and reliable ignition of the actual fuel.

a reply to: Darkpr0

why not dump it in the afterburner using a jp7 /Borane mix? use it intermittently with a combined cycle turbine/scramjet based engine. use the turbine up to Mach 3.5. dump in the borane slush in the afterburner for a few seconds accelerating the aircraft up to Mach 4.5 then engage scram jet. turn off flow and continue on? limited exposure to the abraiding boranes. still getting the job done.


but wait....isn't boron an alkali? throw out the turbine all together and i can think if some really good uses for metal alkali. but thats new old school. personally id rather achieve that means with non equilibrium ionization. saves weight if you got the power.

originally posted by: Darkpr0

originally posted by: yuppa
Ahh ok. Hmm what about developing turbine blades that resist its build up then?

Not buildup, abrasion. The product that gets formed by the reaction is a solid, like sand. It's very hard, much more so than any metal we have. Running the engine on large amounts of it would slowly sandblast the inside of the engine. You could do some crazy stuff like coating the vulnerable parts with ceramic to extend their lifetimes, but this gets astronomically expensive. the TEB (assuming this is what it is) could not be a major constituent of the aircraft's fuel. It would only be an additive, probably solely for even and reliable ignition of the actual fuel.

Got a idea. MAke turbine blades out of that stuff then. That might be a solution.