TNE Only: FF&S Self-Contained Thrusters FC, Size Efficiency, FT, and Fuel Volume

[snrdg082102]

Morning again all,

Is there a maximum thrust rating for the TL-7 Hydrogen Fuel Rocket, the entry below TL 7 Turbofan?

 

[snrdg082102]

Afternoon all,

I just realized I have some more questions about turbojet and turbofan thrusters using after afterburners, so I apologize for bouncing back and forth.

Is the fuel mass, volume, and cost calculated using the thrust output when operating without the afterburner or with the afterburner engaged?

My first take was that the afterburner changed the fuel load, but I'm not sure now that I have the fuel stuff down.

At TL-7+ thrusters that burn HCD can be converted to run on liquid hydrogen.

Can an afterburner be used with liquid hydrogen?

Can an afterburner be used liquid oxygen?

Again, in my first pass I only used afterburners with HCD thrusters and then I started thinking about the liquid hydrogen and liquid oxygen.

 

[aramis]

Afternoon all,

I just realized I have some more questions about turbojet and turbofan thrusters using after afterburners, so I apologize for bouncing back and forth.

Is the fuel mass, volume, and cost calculated using the thrust output when operating without the afterburner or with the afterburner engaged?

My first take was that the afterburner changed the fuel load, but I'm not sure now that I have the fuel stuff down.

At TL-7+ thrusters that burn HCD can be converted to run on liquid hydrogen.

Can an afterburner be used with liquid hydrogen?

Can an afterburner be used liquid oxygen?

Again, in my first pass I only used afterburners with HCD thrusters and then I started thinking about the liquid hydrogen and liquid oxygen.

Yes to both, IIRC. Remembering that the Oxygen is 8x the volume of the hydrogen.

 

[atpollard]

Yes to both, IIRC. Remembering that the Oxygen is 8x the volume of the hydrogen.

I think that oxygen is 8x the mass of hydrogen, but hydrogen is muck 'fluffier' so the oxygen tank is smaller and heavier than the hydrogen tank.
(sorry, I don't remember the volume ratio ... I think that the hydrogen tank is something like 2 to 3 the volume of the oxygen.)

 

[snrdg082102]

Evening aramis and atpollard,

Thank you both for the replies to my question about self-contained thrusters and the use of the optional afterburner.

I'm not sure what your reply of yes to both means aramis so here goes my attempt at expressing my understanding.

My first quest concerned how the fuel load is calculated. As I have the worksheet set-up the fuel load is calculated using tonnes of fuel/hr./tonnes of thrust. Kicking in the afterburner changes the fuel load. I'm thinking that a better way to do the fuel is to on output showing the fuel load without an afterburner and a second one showing the fuel load operating with the afterburner.

I think that aramis said yes that an afterburner can be used by turbojets and turbofans that use liquid hydrogen and liquid oxygen.

TNE FF&S p. 64 allows power plants and thrusters that use liquid hydrogen can modify their fuel tanks to contain half liquid hydrogen and half liquid oxygen. The fuel consumption doubles, adding the liquid oxygen ads Cr50 to the price. When the liquid hydrogen thruster is operating in a standard atmosphere the entire tank can be filled with liquid hydrogen.

TNE FF&S and T4 FF&S do not list, as far as I've found anyway, any additional requirements for liquid oxygen.

I've been working on liquid fuel, hydrogen fuel, and solid fuel rockets per TNE FF&S design requirements. I'm fairly confident I've got the liquid and hydrogen fuel rockets worked out. I'm still unsure about the solid fuel rockets but I seem to have worked out the system. Once I get the self contained thrusters done I'll post my work.

Thank you again for answering my questions, which I hope will help with T4 Book 1 QSDS, book 2 SSDS, and Book B FF&S.

 

[whulorigan]

I think that oxygen is 8x the mass of hydrogen, . . .

Actually, atom for atom (or diatomic molecule for diatomic molecule), Oxygen is 16x the mass of Hydrogen. You are forgetting the neutrons.

 

[snrdg082102]

Moring whulorigan, aramis, and atpollard,

Actually, atom for atom (or diatomic molecule for diatomic molecule), Oxygen is 16x the mass of Hydrogen. You are forgetting the neutrons.

Thank you for the information that oxygen has a mass 16x heavier than hydrogen and takes up about 8x the volume. TNE FF&S and T4 FF&S do not appear to include oxygen's mass and volume into account when calculating the mass and volume of the vehicle.

 

[atpollard]

Actually, atom for atom (or diatomic molecule for diatomic molecule), Oxygen is 16x the mass of Hydrogen. You are forgetting the neutrons.

OK, no more leaky memory for me ... let's look it up:

FROM Encyclopedia Astronautica (Lox/LH2):

Oxidizer: LOX. [Liquid Oxygen]
Fuel: LH2. [Liquid Hydrogen]
Propellant Formulation: LOX/LH2. ............................ Propellant Formulation: LOX/Slush LH2.
Optimum Oxidizer to Fuel Ratio: 6. ........................... Optimum Oxidizer to Fuel Ratio: 4.
Temperature of Combustion: 2,985 deg K. ................ Temperature of Combustion: 2,985 deg K.
Ratio of Specific Heats: 1.26. ................................. Ratio of Specific Heats: 1.26.
Density: 0.28 g/cc. .............................................. Density: 0.33 g/cc.
Characteristic velocity c: 2,435 m/s (7,988 ft/sec). ... Characteristic velocity c: 2,435 m/s (7,988 ft/sec).
Isp Shifting: 391 sec. ........................................... Isp Shifting: 391 sec.
Isp Frozen: 388 sec. ............................................ Isp Frozen: 388 sec.
Mol: 10.00 M (32.00 ft). ....................................... Mol: 10.00 M (32.00 ft).
Oxidizer Density: 1.140 g/cc. ................................ Oxidizer Density: 1.140 g/cc.
Oxidizer Freezing Point: -219 deg C. ....................... Oxidizer Freezing Point: -219 deg C.
Oxidizer Boiling Point: -183 deg C. .......................... Oxidizer Boiling Point: -183 deg C.
Fuel Density: 0.071 g/cc. ..................................... Fuel Density: 0.071 g/cc.
Fuel Freezing Point: -259 deg C. ............................ Fuel Freezing Point: -259 deg C.
Fuel Boiling Point: -253 deg C. ............................... Fuel Boiling Point: -253 deg C.
Specific impulse: 451 s.
Specific impulse sea level: 391 s.

So going with the denser Hydrogen slush ...

Optimum ratio is 4 parts Lox to 1 part LH2 slush.
One metric tonne of fuel = 1000 kg of fuel (Lox & LH2 slush) = 800 kg Lox & 200 kg LH2 slush.
Lox: 800 kg / 1,140 kg/cu.m. = 0.7018 cubic meters.
LH2 slush: 200 kg / 71 kg/cu.m. = 2.8169 cubic meters.

So 1 metric tonne of Lox/LH2 fuel will be 800 kg (0.7 cu.m) of Lox and 200 kg (2.8 cu.m.) of LH2.

The ratio of Lox to LH2 is about 4:1 by mass and 1:4 by volume.
So the LH2 tank will be 4 times the volume of the Lox tank, but weigh only 1/4 as much.

(I would have given the values in dTons, but I didn't remember if TNE used 1 dT = 14 cu.m or 1 dT = 13.5 cu.m.)

 

[snrdg082102]

Morning atpollard,

OK, no more leaky memory for me ... let's look it up:

FROM Encyclopedia Astronautica (Lox/LH2):

Oxidizer: LOX. [Liquid Oxygen]
Fuel: LH2. [Liquid Hydrogen]
Propellant Formulation: LOX/LH2. ............................ Propellant Formulation: LOX/Slush LH2.
Optimum Oxidizer to Fuel Ratio: 6. ........................... Optimum Oxidizer to Fuel Ratio: 4.
Temperature of Combustion: 2,985 deg K. ................ Temperature of Combustion: 2,985 deg K.
Ratio of Specific Heats: 1.26. ................................. Ratio of Specific Heats: 1.26.
Density: 0.28 g/cc. .............................................. Density: 0.33 g/cc.
Characteristic velocity c: 2,435 m/s (7,988 ft/sec). ... Characteristic velocity c: 2,435 m/s (7,988 ft/sec).
Isp Shifting: 391 sec. ........................................... Isp Shifting: 391 sec.
Isp Frozen: 388 sec. ............................................ Isp Frozen: 388 sec.
Mol: 10.00 M (32.00 ft). ....................................... Mol: 10.00 M (32.00 ft).
Oxidizer Density: 1.140 g/cc. ................................ Oxidizer Density: 1.140 g/cc.
Oxidizer Freezing Point: -219 deg C. ....................... Oxidizer Freezing Point: -219 deg C.
Oxidizer Boiling Point: -183 deg C. .......................... Oxidizer Boiling Point: -183 deg C.
Fuel Density: 0.071 g/cc. ..................................... Fuel Density: 0.071 g/cc.
Fuel Freezing Point: -259 deg C. ............................ Fuel Freezing Point: -259 deg C.
Fuel Boiling Point: -253 deg C. ............................... Fuel Boiling Point: -253 deg C.
Specific impulse: 451 s.
Specific impulse sea level: 391 s.

So going with the denser Hydrogen slush ...

Optimum ratio is 4 parts Lox to 1 part LH2 slush.
One metric tonne of fuel = 1000 kg of fuel (Lox & LH2 slush) = 800 kg Lox & 200 kg LH2 slush.
Lox: 800 kg / 1,140 kg/cu.m. = 0.7018 cubic meters.
LH2 slush: 200 kg / 71 kg/cu.m. = 2.8169 cubic meters.

So 1 metric tonne of Lox/LH2 fuel will be 800 kg (0.7 cu.m) of Lox and 200 kg (2.8 cu.m.) of LH2.

The ratio of Lox to LH2 is about 4:1 by mass and 1:4 by volume.
So the LH2 tank will be 4 times the volume of the Lox tank, but weigh only 1/4 as much.

(I would have given the values in dTons, but I didn't remember if TNE used 1 dT = 14 cu.m or 1 dT = 13.5 cu.m.)

TNE and T4 both agree that 1 displacement ton = 14 m^3

 

[atpollard]

So 1 metric tonne of Lox/LH2 fuel will be 800 kg (0.7 cu.m) of Lox and 200 kg (2.8 cu.m.) of LH2.

The ratio of Lox to LH2 is about 4:1 by mass and 1:4 by volume.
So the LH2 tank will be 4 times the volume of the Lox tank, but weigh only 1/4 as much.

(I would have given the values in dTons, but I didn't remember if TNE used 1 dT = 14 cu.m or 1 dT = 13.5 cu.m.)

Morning atpollard,
TNE and T4 both agree that 1 displacement ton = 14 m^3

In that case, 1 dTon of (Lox/LH2) = 14 cu.m. = 3,987 kg.
Of that 1 dTon, Lox will be 2.8 cu.m (3,192 kg) and LH2 will be 11.2 cu.m. (795 kg).

If you wanted to round off for simplification, 1 displacement Ton of fuel (Lox/LH2) will weigh about 4 metric tonnes, and the fuel storage volume will be 20% oxygen tanks and 80% hydrogen tanks.

 

[snrdg082102]

Afternoon atpollard,

Quote:
Originally Posted by atpollard
In that case, 1 dTon of (Lox/LH2) = 14 cu.m. = 3,987 kg.
Of that 1 dTon, Lox will be 2.8 cu.m (3,192 kg) and LH2 will be 11.2 cu.m. (795 kg).

If you wanted to round off for simplification, 1 displacement Ton of fuel (Lox/LH2) will weigh about 4 metric tonnes, and the fuel storage volume will be 20% oxygen tanks and 80% hydrogen tanks.

TNE FF&S p. 70 lists the following fuel data for Liquid Hydrogen (LH2)

LHyd (Liquid Hydrogen); Density: 0.07; Price Cr35.
Fuel Volume in m^3 per tonne of thrust = the mass (in metric tonnes) consumed per hour per tonne of thrust ÷ by the fuel density.

Looks like liquid oxygen (LOX) needs to be added to TNE FF&S to take the requirements for adding it to the design sequence.

The entry on TNE FF&S p. 70 for Air-Breathing Engines states that they have the same limitations as air-breathing power and sends the designer to Atmospheric Performance on p. 64.

I added liquid oxygen to the fuel type table using the information on TNE FF&S p. 64.

The entry I have is

LOX (Liquid Oxygen): Density: 1; Price: Cr50.

From the information provided is the Density of 1 correct?

If not what density should be used?

Should the information for liquid oxygen be submitted as errata?

I'll probably being asking about this item on the T4 forum too.

 

[elbmc1969]

Thank you for the information that oxygen has a mass 16x heavier than hydrogen and takes up about 8x the volume. TNE FF&S and T4 FF&S do not appear to include oxygen's mass and volume into account when calculating the mass and volume of the vehicle.

No, oxygen takes up less volume than hydrogen.

 

[snrdg082102]

Hello elbmc1969,

No, oxygen takes up less volume than hydrogen.

Thank you for the correction, especially after atpollard's two posts showing the relationship.

 

[elbmc1969]

Looks like liquid oxygen (LOX) needs to be added to TNE FF&S to take the requirements for adding it to the design sequence.

Should the information for liquid oxygen be submitted as errata?

Just to be perfectly clear, you can't use liquid oxygen as a fuel. I don't think it belongs on the fuels table.

The rule on p. 64 [7] is clearly an abstraction, but it's probably close enough that it doesn't need to be errata'd.

 

[elbmc1969]

Morning again all,

Is there a maximum thrust rating for the TL-7 Hydrogen Fuel Rocket, the entry below TL 7 Turbofan?

Not according to anything that I can find. I don't understand why there wouldn't be. It probably needs errata and max is definitely 5000 or less (probably less). Almost certainly more than the 1500 from a TL6 liquid fueled rocket. From TL6 to TL7, solid fueled rockets increase maximum thrust 2.5 times. That's where I got the 5000 as a max.

 

[snrdg082102]

Hello again elbmc1969,

thank you for your help.

Just to be perfectly clear, you can't use liquid oxygen as a fuel. I don't think it belongs on the fuels table.

The rule on p. 64 [7] is clearly an abstraction, but it's probably close enough that it doesn't need to be errata'd.

I added LOX to my spreadsheet's fuel table so I could look the option up, which is the main reason I suggested adding values to the table in the book.

I wasn't thinking about it being a fuel, so I was off base with my question.

Not according to anything that I can find. I don't understand why there wouldn't be. It probably needs errata and max is definitely 5000 or less (probably less). Almost certainly more than the 1500 from a TL6 liquid fueled rocket. From TL6 to TL7, solid fueled rockets increase maximum thrust 2.5 times. That's where I got the 5000 as a max.

At least I don't seem to be on the wrong track thinking that the HF Rocket might be missing a Max Thrust limit.

I'm not very knowledgeable in this area and I haven't done any research but if one follows the trend on the table that would put the MaxT of the HF rocket at 3,750. Depending on the rounding the MaxT could be either 3,800 or 4,000.

I'm going to see what I can find on the Internet and may be visit my local library to see what I can dig up.

Again thank-you for your replies.