- United States Patent
- Patent number: 5,305,974
- Date of patent: Apr. 26, 1994
- Spaceship Propulsion by Momentum Transfer
A propulsion system for spaceships wherein a first electromagnetic projectile
launcher(EMPL) accelerates "smart" projectiles into space and on appropriate
trajectories to rendezvous with a distant spaceship at some later time. The smart
projectiles stabilize themselves in space using a system of on board thrusters operated by
computers. Laser beams and radio transmissions are directed at the spaceship and are
monitored by sensors aboard the spaceship. Computers on board the spaceship determine any
necessary course corrections for the projectiles based upon the spaceship's sensor system.
Appropriate commands are radioed to the projectiles which execute the commanded maneuvers
to alter their trajectories. The spaceship carries a second EMPL and a nuclear-powered
electricity generating facility to provide electricity to operate the EMPL. The spaceship,
the second EMPL and the nuclear power facility are all rotated axially about the long axis
of the EMPL to provide both gyroscopic stabilization and also artificial gravity for the
crew of the spaceship. The second EMPL is used to catch the projectiles which transfers
the momentum of the projectiles to the spaceship thereby accelerating it in the desired
direction. Additional acceleration of the spaceship is achieved by again launching the
captured projectiles in a direction opposite to the desired direction of motion of the
spaceship. The spaceship can be decelerated in a similar manner. Mars can be reached in
two months using this system.
Fixed these links 02/23/01
Why is my propulsion system better?
Because the specific impulse of my propulsion system is at
least 3300 seconds and can be increased up to 10,000 seconds. Perhaps you don't know
what specific impulse is. Well, specific impulse is defined to be the ratio of the thrust
of the rocket to the weight flow rate of the propellant. When stated in this manner it is
difficult to understand. A simpler way to express it is the number of seconds that one
pound of propellant would burn while producing one pound of thrust. It is a measure of the
energy in the propellant.
The following is a table of specific impulses of various different propulsion systems.
- Specific Impulse Comparions
||Specific Impulse (sec)
|LOX-LH2 (space shuttle system)
||450 - 475
|O-BeH (most energetic chemical propellant)
||900 - 1000
|Nuclear thermal rocket (fission)
| solid core
||500 - 1100
| liquid core
||1300 - 1600
| gas core
||3000 - 7000
|(*) Nuclear electric rocket
||800 - 30000
|Momentum exchange (my system)
||3000 - 10000
|(*) Ion drive (such as NASA Deep Space 1)
||3000 - 25000
|(*) Nuclear fusion rocket
|(*) Anti-matter rocket
|(*) Photon drive (light beam)
The problem with all systems marked by (*) is that their total thrust is very low. Take
the Ion drive used by the Nasa Deep Space 1 project. Its total thrust is measured in
ounces (see Popular Science, 7/98, p.44) These systems are therefore useless
for transporting people to distant planets or other destinations.
So far it is still not clear why higher specific impulse is good - or how good it is.
Let me give you a practical example. Consider the famous rocket equation given below:
- M/m = exp( dv/g*Isp )
- M = initial total mass
- m = final total mass (after the fuel is used up)
- M/m = mass ratio
- exp =
"e" raised to the power of ( dv/g*Isp )
- dv = total delta velocity
- g = acceleration of gravity
- Isp = specific impulse of the fuel or the propulsion system
My plan calls for an outward velocity of 20 km/sec and the same for the return trip.
This amounts to a total delta velocity of 40 km/sec or 40,000 m/sec.
Let's calculate the mass ratio for a LOX-LH2 rocket:
We have: M/m = exp(40000/9.8 * 450) = exp(9.07) = 8693
Now we do the same for a nuclear thermal rocket with an Isp of 950 secs.
We now have: M/m = exp(40000/9.8 * 950) = exp(4.296) = 73
Finally, try my system with an Isp of 3300 secs.
Now we get: M/m = exp(40000/9.8 * 3300) = exp(1.24) = 3.44
The results are summarized in the table below.
Comparison of Propulsion Systems for 3000 MT Spaceship
||Total Cost at $1M/MT