Green Propellant to Replace Hydrazine

[RuBisCO]

This year (hopefully) the next Falcon Heavy launch will lift a little engineering project among its many customer mini-satilites called "Green Propellant Infusion Mission". This little <181 kg satilite will test a new alternative monopropellant called AF-M315E (hydroxylammonium nitrate (NH₃OHNO₃) fuel/oxidizer blend, the added fuel is apparently secret). AF-M315E has 12% higher Isp (257 vs. 235 sec) compared to hydrazine, and is 45% more dense (1.47 vs. 1.00 g/ml), is as stable if not more so ("significantly reduced sensitivity to adiabatic compression than hydrazine"). Most importantly of all AF-M315E relatively non-toxic, unlike hydrazine which is a decent nerve gas, and thus does not need a hazmat crew to load/off-load and thus greatly reducing handling costs.

What is sad is reading from the book "Ignition!" shows signifgent work on nitrate ammonium ionic liquid fuel/oxidizer blends had been done in the 1950's and it is likely the military has kept this stuff secret for decades. This fuel should become the monopropellant of choice for satilites >100 kg as attitude control and orbital maneuvering propellant. According to the below study if used for a Mars Skycrane setup in place of hydrazine it would increase the landing cargo capacity by 58 kg and if used for WFIRST would save >160 kg of mass. Its greater density and simpiliar-lighter monopropellant nature means it could also take a chunk out of the N2O4-MMH bi-propellant thrusters buisness as well.   

https://www.rocket.com/files/aerojet/documents/Capabilities/PDFs/GPIM AF-M315E Propulsion System.pdf

[kerbiloid]

It's hot!

Literally.  Melting point = 48°C.

[Wjolcz]

The same stuff that was launched and tested on Electron?

[RuBisCO]

9 hours ago, kerbiloid said:

It's hot!

Literally.  Melting point = 48°C.

I assume the fuel blended in reduces the melting point signifigently. In fact:

"AF-M315E also is expected to improve overall vehicle performance. It boasts a higher density than hydrazine, meaning more of it can be stored in containers of the same volume. In addition, it delivers a higher specific impulse, or thrust delivered per given quantity of fuel, and has a lower freezing point, requiring less spacecraft power to maintain its temperature."

But I guess like the secret added fuel its melting point is classified as well. But according to this (page 22) the melting point is below 0°C but I guess above -22°C where it begins to freeze into a "glass".  

5 hours ago, Wjolcz said:

The same stuff that was launched and tested on Electron?

Maaayyybeee, I think only they know. 

Edited July 11, 2018 by RuBisCO
added link to freezing point

[YNM]

4 hours ago, RuBisCO said:

But I guess like the secret added fuel its melting point is classified as well.

You want this stuff to be classified, otherwise they'd launch you their 'green' missiles.

 

Still, all sounds exciting.

Here's hoping the forces ain't putting green paint over the whole report to make it look better.

[RuBisCO]

On 7/11/2018 at 10:53 AM, YNM said:

You want this stuff to be classified, otherwise they'd launch you their 'green' missiles.

 

Still, all sounds exciting.

Here's hoping the forces ain't putting green paint over the whole report to make it look better.

Well I think it is a little late for that if they are going to fly it soon and try to push it on the open market, they are going to eventually have to release the fuel recipe. 

What bothers me again is that this research was going on since the 1950's, like I said before the book ignition has a whole chapter dedicated to experiments on making better mono-propellants ending with nitrate ammonium ionic liquid fuel/oxidize blends of excellent performance and stability, so I suspect the US military has been keeping this stuff under wraps for decades as torpedo propellant or such. 

Another problem is Infrastructure lock/inertia: If you are dropping millions/billions of dollars for a spacecraft you want reliability and flight proven performance over better efficiency. Thus technological improvement is hampered because everyone is buying the old reliable stuff.

Edited July 12, 2018 by RuBisCO
added link

[K^2]

NH₃? OH NO₃!

Seriously, though, if this works out, we need a better name for it.

[magnemoe]

On 7/11/2018 at 10:05 AM, Wjolcz said:

The same stuff that was launched and tested on Electron?

Might be, note that the main benefit as Scott Manley pointed out is not environmental but safety as hydrazine is idiotic dangerous, you has to handle it in hazmat suits with internal air for one. It also makes the fueled satellite dangerous to handle. This is not an major issue for very expensive satellites but an major issue for cheap testbed stuff like cubesat and for mass produced ones. 

And no its not an major military use either think only US missiles using monoprop is ICBM final stage or warhead buss, cost is not much of an issue here. 
 

[YNM]

6 hours ago, RuBisCO said:

if they are going to fly it soon and try to push it on the open market, they are going to eventually have to release the fuel recipe. 

They can just let select manufacturers to produce them, and it will come in a single ready-to-use package with heavily limited export. Much like how US satellite busses weren't allowed to be launched in a 'foreign' nation.

[kerbiloid]

From wiki.

Quote

It will be used in a fuel/oxidizer blend known as "AF-M315E" in the high thrust engines of the Green Propellant Infusion Mission in 2017.^[5][6][7] The specific impulse of AF-M315E is 257 s.

257 s looks too low for a launch vehicle, much worse than methalox or kerolox.

But at the same time the mixture/solution looks much more expensive than both of them.

Quote

 it offers 50% higher performance for a given propellant tank compared to commercially used Hydrazine.

If it has 257 s of ISP, probably performance here is a tank mass.
So, a 100 kg propellant tank will mass not 110 kg, but just 105?

Orbital crafts need not so much fuel, and are usually uncrewed, so doesn't matter how much toxic it is. 

[YNM]

1 hour ago, kerbiloid said:

257 s looks too low for a launch vehicle, much worse than methalox or kerolox.

You can't store LOX for years with minutes-to-launch requirements.

 

Tradeoffs is always good.

[kerbiloid]

26 minutes ago, YNM said:

You can't store LOX for years with minutes-to-launch requirements.

Hydrazine and MMH can be stored for years and are much cheaper.

[magnemoe]

1 hour ago, kerbiloid said:

Hydrazine and MMH can be stored for years and are much cheaper.

Yes but hydrazine is very expensive to handle as its so toxic. This becoming more of an issue with cheaper launches with cheap mass produced satellites and more testbed satellites. 

[kerbiloid]

13 minutes ago, magnemoe said:

Yes but hydrazine is very expensive to handle

Afaik, in 1974 in USA 17 000 t of hydrazine was produced. It's one of heavy tonnage chemical products used in many ways (plastic, resin, medicines, insecticides, so on).

13 minutes ago, magnemoe said:

as its so toxic.

Any chemical or metallurgical plant has much greater amounts of much more toxic compounds. (And drops them into a river or air)
Also there is "ampulisation", a common practice when a whole hypergolic ICBM is hermetically packed into a launch tube pressurized with inert gas, and is used with no contact between the crew and the fuel.

Edited July 13, 2018 by kerbiloid

[magnemoe]

1 minute ago, kerbiloid said:

Afaik, in 1974 in USA 17 000 t of hydrazine was produced. It's one of heavy tonnage chemical products used in many ways.

Any chemical plant has much greater amounts of much more toxic compounds.
Also there is "ampulisation", a common practice when a whole hypergolic ICBM is hermetically packed into a launch tube, and is used with no contact.

True, its ways to handle it safely however its add an cost and that cost would be pretty fixed if your satellite uses 500 kg or 2. 

Do capsules dump their hydrazine during decent? thinking if they do an rough landing like the Soyuz there the retrorocket did not fire you could get leaks and have injured astronaut in the capsule. 

[kerbiloid]

15 minutes ago, magnemoe said:

Do capsules dump their hydrazine during decent?

Afaik, Apollo lands on it. Its RCS is between the cabin and the heatshield. 
Mercury and Gemini keep it under the chute box, outside of capsule.
Soyuz doesn't use. Afaik, it has a 30 kg peroxide barrel inside, right under a spaceman's head. It has it in a service module which doesn't land.
TKS VA jettisons the RCS after aerobraking and lands with no liquid fuel. FGB has ~4 t of hypergolics in tanks, and there are several tens kg in VA RCS.
About Orion and CST-100 not sure, probably like Apollo.
Crewed Dragon (ta-dam!) is going to land on it. What a frightening idea. Either SpaceX doesn't know how dangerous are hypergolics, or they don't give a flag.

So, the retrorocketed capsules don't have hypergolics on landing.
Except Crew Dragon, which metaphysically looks like a 

Spoiler

P.S.
It's nice at all: people are sure at once that hydrazine is an apocaliptic venom, and that Crew Dragon (lands with it) is a future new word in technics.

Edited July 13, 2018 by kerbiloid

[RuBisCO]

Handling cost is the problem, not the cost of propellant its self.

"A 2012 Ph.D. dissertation by Christyl Johnson, now NASA Goddard’s deputy director for technology and research investments, found that the pre-launch processing and handling costs for the Swedish launch of a spacecraft powered by ammonium dinitramide, a green propellant that is more hazardous than the GPIM propellant, were $437,955 less than the equivalent costs for hydrazine. The U.S. Department of Transportation is reviewing proposed rules for the GPIM green fuel so that spacecraft builders can ship fully fueled, ready-to-launch green-propellant spacecraft across the country. The only step required at the launch site would be pressurizing the fuel tanks." --- https://aerospaceamerica.aiaa.org/features/green-propellant/

Despite the lower ISP then N2O4/MMH, it is a monopropellant and thus requires half the piping and valves, the costs saving and reliability increase (ever valve is a possible failure mode) for low delta-v task like attitude control, station keeping and orbital maneuvers are worthwhile and why hydrazine is often used in place of N2O4/MMH despite the significantly lower ISP.  

Edited July 13, 2018 by RuBisCO

[YNM]

4 hours ago, kerbiloid said:

Hydrazine and MMH can be stored for years and are much cheaper.

 

On 7/11/2018 at 9:32 AM, RuBisCO said:

AF-M315E has 12% higher Isp (257 vs. 235 sec) compared to hydrazine, and is 45% more dense (1.47 vs. 1.00 g/ml), is as stable if not more so ("significantly reduced sensitivity to adiabatic compression than hydrazine"). Most importantly of all AF-M315E relatively non-toxic, unlike hydrazine which is a decent nerve gas, and thus does not need a hazmat crew to load/off-load and thus greatly reducing handling costs.

read.

[kerbiloid]

2 minutes ago, YNM said:

read.

already

I.e. replacing a cheap and common hydrazine with a mixture of liquids, one of which has melting point 48°C, being studied since 1950s with no application.
For ISP +10% and a fuel tank weighting 7% of fuel mass rather than 10%.

 

[YNM]

12 minutes ago, kerbiloid said:

I.e. replacing a cheap and common hydrazine with a mixture of liquids, one of which has melting point 48°C, being studied since 1950s with no application.
For ISP +10% and a fuel tank weighting 7% of fuel mass rather than 10%.

Maybe you should try ask the military top brass.

[RuBisCO]

9 minutes ago, kerbiloid said:

already

I.e. replacing a cheap and common hydrazine with a mixture of liquids, one of which has melting point 48°C, being studied since 1950s with no application.
For ISP +10% and a fuel tank weighting 7% of fuel mass rather than 10%.

 

Aaah when you mix miscible liquids, you get a new melting point.

Yeah and electric cars have been studied since the 1880's too... so what?  

[kerbiloid]

3 minutes ago, RuBisCO said:

Yeah and electric cars have been studied since the 1880's too... so what?  

Any new and really used rocket fuels since 1950s? Green dragon, luminal-a, acetam... All of them were promising.

Edited July 13, 2018 by kerbiloid

[YNM]

@RuBisCO My only concern is that the Forces are not actually being that honest and is painting green over the reds. I hope it's not true, but who knows.

1 minute ago, kerbiloid said:

Any new and really used rocket fuels since 1950s?

We're talking of the military here.

Maybe you should ask the same to your own one.

[kerbiloid]

8 minutes ago, YNM said:

We're talking of the military here.

Two of three listed were serious military studies with a lot of experiments.

[RuBisCO]

2 minutes ago, kerbiloid said:

Any new and really used rocket fuels since 1950s? Green dragon, luminal-a, acetam... All of them were promising.

You are comparing propellants that were too difficult to work with, to infrastructure lock:

The main challenge for NASA and proponents of the green monopropellant fuel is to convince space mission planners that the alternative fuel and its thrusters, which have never flown in space, won’t fail. Hydrazine is well-understood, as are its effects on components.

“It’s very complex getting these new systems accepted on spacecraft, by the spacecraft user community, especially when you’re talking half-billion-dollar geocom assets and can we actually put new technology on them,” McLean says. Almost all of today’s commercial Earth-orbiting spacecraft are propelled by 1960s-era-thruster designs. New fuels have “a lot of inertia to overcome,” he says.

One key to acceptance is flight heritage: showing that a green-fuel-powered spacecraft has flown in orbit — starting with a single flight — without failing. “That gives us the ability to point back and say, ‘Hey, we’ve been through everything it takes to get this thing manufactured, integrated, processed, launched and operational,’” McLean says. “Every single one of those [steps] is a huge hurdle to overcome technically.”

 --- https://aerospaceamerica.aiaa.org/features/green-propellant/

Look name me a inferiority of AF-M315E specifically?