Thread: Fusion Rocket Drives

I have some questions for everyone regarding Fusion Rocket drives.

Someone somewhere at some point in the past mentioned something about
these only really being used for unmanned spacecraft due to the inherent
dangers.

A) What are these dangers? (Apart from the exhaust)

B) As this is the only feasible sub-light drive available at TL 9 for
interplanetary vessels, would it not be reasonable to say that manned
ships used them up until HEPlaR?

C) Am I reading the rules for Fuel Consumption for these drives correctly?
It’s per ton of thrust, not per MW like HEPlaR? And ridiculously low at
that (which makes up for the required volume/mass, granted)?

As far as I know there is no other danger to fusion drives other that the exhaust. I've heard other's say they don't allow it in their settings due to the plant itself giving off deadly radiation, but I believe this is one of those time that qualify as (IMTU).
I have a question of my own. Why would the drive need to spew out radioactive exhaust. Current day reactors use a closed loop system to cool the reactor. If I remember right, coolant water (radioactive) is sent along pipes to heat water(non radioactive) into steam this steam spins turbines to make electricity. This steam water is then cooled and the process started all over again. My question, could not non radioactive liquid hydrogen be heated up in the same way as the non radioactive water, then squirted out the back as clean exhaust?
A second question I just thought of. Can a fusion drive equipped ship land on a world without microwaving everyone by just shutting off its fusion drive and using an auxiliary drive? Or does no-one want to take the chance that some knucklehead might flip the wrong switch and no landing is a safety measure?
The fuel consumption is correct (at least I haven't seen any errata contradicting it)
If you don't mind going off the FF+S range check out Missouri Archives---Alternate Thrusters. I found one that is quite interesting called Heat Jet. This is apparently a real world thruster that NASA is/was working on. Its low-tech (8-9) acts much like HEPlaR, but the fuel costs make you dream of HEPlaR.
Let me know what you think of it, as I've been thinking of allowing it as a auxiliary drive for fusion drives.
PS: If you want to leave the possibility of irradiating the crew as a danger how far from the engine would you need to be to be safe. I'm thinking of the space ship used in the movie "Mars". A big honking engine aft with a thin frame running to a command deck? forward and a revolving living quarters next to the bridge. Leave it to Hollywood to come up with a cool design for a ship.

To my mind the primary radioactive danger would be with the engine itself as you specify but it is also that the fuel would be heated to a plasma yes?  would it be fused as part of the process (I've never really considered this so for me it's an open question)  If the fuel is just heated to a plasma state and allowed to thrust out then the exhaust would eventually become non-threatening as it dispersed.  The danger to crew would be the drive itself and the highly energetic plasma thrust (think x-15 rocket plane or the shuttle exhaust - you don't want to get in the way of that, precludes long life expectancy)
T

--- On Wed, 5/26/10, roger <> wrote:

From: roger <>
Subject: [Traveller_TNE] Fusion Rocket Drives
To:
Date: Wednesday, May 26, 2010, 3:07 PM

 

As far as I know there is no other danger to fusion drives other that the exhaust. I've heard other's say they don't allow it in their settings due to the plant itself giving off deadly radiation, but I believe this is one of those time that qualify as (IMTU).
I have a question of my own. Why would the drive need to spew out radioactive exhaust. Current day reactors use a closed loop system to cool the reactor. If I remember right, coolant water (radioactive) is sent along pipes to heat water(non radioactive) into steam this steam spins turbines to make electricity. This steam water is then cooled and the process started all over again. My question, could not non radioactive liquid hydrogen be heated up in the same way as the non radioactive water, then squirted out the back as clean exhaust?
A second question I just thought of. Can a fusion drive equipped ship land on a world without microwaving everyone by just shutting off its fusion drive and using an auxiliary drive? Or does no-one want to take the chance that some knucklehead might flip the wrong switch and no landing is a safety measure?
The fuel consumption is correct (at least I haven't seen any errata contradicting it)
If you don't mind going off the FF+S range check out Missouri Archives---Alternate Thrusters. I found one that is quite interesting called Heat Jet. This is apparently a real world thruster that NASA is/was working on. Its low-tech (8-9) acts much like HEPlaR, but the fuel costs make you dream of HEPlaR.
Let me know what you think of it, as I've been thinking of allowing it as a auxiliary drive for fusion drives.
PS: If you want to leave the possibility of irradiating the crew as a danger how far from the engine would you need to be to be safe. I'm thinking of the space ship used in the movie "Mars". A big honking engine aft with a thin frame running to a command deck? forward and a revolving living quarters next to the bridge. Leave it to Hollywood to come up with a cool design for a ship.

http://www.arcraftplasma.com/welding/index.htm
and here is another link with info about plasma on it, though it needs to
searched over for it.
http://www.physicstoday.org/
since plasma is currenlty in its infant state, and is already in industrial
uses, among others, i suspect that plasma per se is nil for danger except
for the extreme heat. so i would agree the rad hazard would lie primarily in
the engines themselves.

On Wed, May 26, 2010 at 5:21 PM, Tim O'Reilly <> wrote:

>
>
> To my mind the primary radioactive danger would be with the engine
> itself as you specify but it is also that the fuel would be heated to a
> plasma yes? would it be fused as part of the process (I've never really
> considered this so for me it's an open question) If the fuel is just heated
> to a plasma state and allowed to thrust out then the exhaust would
> eventually become non-threatening as it dispersed. The danger to crew would
> be the drive itself and the highly energetic plasma thrust (think x-15
> rocket plane or the shuttle exhaust - you don't want to get in the way of
> that, precludes long life expectancy)
> T
>
> --- On *Wed, 5/26/10, roger <>* wrote:
>
>
> From: roger <>
> Subject: [Traveller_TNE] Fusion Rocket Drives
> To:
> Date: Wednesday, May 26, 2010, 3:07 PM
>
>
>
> As far as I know there is no other danger to fusion drives other that the
> exhaust. I've heard other's say they don't allow it in their settings due to
> the plant itself giving off deadly radiation, but I believe this is one of
> those time that qualify as (IMTU).
> I have a question of my own. Why would the drive need to spew out
> radioactive exhaust. Current day reactors use a closed loop system to cool
> the reactor. If I remember right, coolant water (radioactive) is sent along
> pipes to heat water(non radioactive) into steam this steam spins turbines to
> make electricity. This steam water is then cooled and the process started
> all over again. My question, could not non radioactive liquid hydrogen be
> heated up in the same way as the non radioactive water, then squirted out
> the back as clean exhaust?
> A second question I just thought of. Can a fusion drive equipped ship land
> on a world without microwaving everyone by just shutting off its fusion
> drive and using an auxiliary drive? Or does no-one want to take the chance
> that some knucklehead might flip the wrong switch and no landing is a safety
> measure?
> The fuel consumption is correct (at least I haven't seen any errata
> contradicting it)
> If you don't mind going off the FF+S range check out Missouri
> Archives---Alternate Thrusters. I found one that is quite interesting called
> Heat Jet. This is apparently a real world thruster that NASA is/was working
> on. Its low-tech (8-9) acts much like HEPlaR, but the fuel costs make you
> dream of HEPlaR.
> Let me know what you think of it, as I've been thinking of allowing it as a
> auxiliary drive for fusion drives.
> PS: If you want to leave the possibility of irradiating the crew as a
> danger how far from the engine would you need to be to be safe. I'm thinking
> of the space ship used in the movie "Mars". A big honking engine aft with a
> thin frame running to a command deck? forward and a revolving living
> quarters next to the bridge. Leave it to Hollywood to come up with a cool
> design for a ship.
>
>
>
>

--
The scientists of today think deeply instead of clearly. One must be sane to
think clearly, but one can think deeply and be quite insane.
Nikola Tesla

Fair enough. I do try to stick as closely as possible to the actual rules, so I guess IMTU it will only be the exhaust that will be radioactive. Which begs the question, how do you "brake" without radiating the crew? I guess the ships themselves must have radiation shielding on the hull (which, now that I think about it makes perfect sense...only no one better be working on the hull while the ship is braking...which I guess they wouldn't be anyway).

Also IMTU, I have determined that fusion drive equiped ships are not allowed in a world's atmosphere at all, but this is because of the safety reason you mentioned, not because they "couldn't" do so with the drive turned off. In "reality", however, it is almost a moot point as these drives have substantial mass, and to combine that with the mass required for contra-grav engines means that the ship's overall mass is going to be more then I want to have to consider. For me, it comes down to a choice between the two. Either I design with CG-engines to allow easy transfer from planet's surface to orbit and use any other drive, or I design with fusion drives for interplanetary trips but do not allow such ships to land on a world with an atmosphere.

I am very curious as to this Heat Jet tech you mentioned. I tried Googleing for it, but didn't see anything. Could you provide a link to some information? (I did find an article titled "Reduced Gravity Testing of a Refrigerant-Based Cold Gas Thruster", but I don't know if that's what you are refering to.)

----- Original Message -----
From: roger
To:
Sent: Wednesday, May 26, 2010 1:07 PM
Subject: [Traveller_TNE] Fusion Rocket Drives

As far as I know there is no other danger to fusion drives other that the exhaust. I've heard other's say they don't allow it in their settings due to the plant itself giving off deadly radiation, but I believe this is one of those time that qualify as (IMTU).
I have a question of my own. Why would the drive need to spew out radioactive exhaust. Current day reactors use a closed loop system to cool the reactor. If I remember right, coolant water (radioactive) is sent along pipes to heat water(non radioactive) into steam this steam spins turbines to make electricity. This steam water is then cooled and the process started all over again. My question, could not non radioactive liquid hydrogen be heated up in the same way as the non radioactive water, then squirted out the back as clean exhaust?
A second question I just thought of. Can a fusion drive equipped ship land on a world without microwaving everyone by just shutting off its fusion drive and using an auxiliary drive? Or does no-one want to take the chance that some knucklehead might flip the wrong switch and no landing is a safety measure?
The fuel consumption is correct (at least I haven't seen any errata contradicting it)
If you don't mind going off the FF+S range check out Missouri Archives---Alternate Thrusters. I found one that is quite interesting called Heat Jet. This is apparently a real world thruster that NASA is/was working on. Its low-tech (8-9) acts much like HEPlaR, but the fuel costs make you dream of HEPlaR.
Let me know what you think of it, as I've been thinking of allowing it as a auxiliary drive for fusion drives.
PS: If you want to leave the possibility of irradiating the crew as a danger how far from the engine would you need to be to be safe. I'm thinking of the space ship used in the movie "Mars". A big honking engine aft with a thin frame running to a command deck? forward and a revolving living quarters next to the bridge. Leave it to Hollywood to come up with a cool design for a ship.