Re: Agenda physics in Wikipedia? - nuclear fission efficiency of 0.1%

In sci.physics Dave <dwickford@yahoo.com> wrote:

On 24 42, Jim Pennino wrote:

In sci.physics Dave <dwickford@yahoo.com> wrote:

Reading
http://en.wikipedia.org/wiki/Photon_rocket,
an onboard nuclear engine doesn't look good,
despite me thinking it is the best option to
get a rover to an exoplanet.
>
Then I looked into why, and the gamma efficiency
is given as 0.1% for fission,
this seem like 100 times too low,
resulting in a maximum quoted speed of 60km/s.
>
There are other options also, like having an
open gamma ray source. This has the advantage of
no moving parts, just don't look into the beam.
>
Posted to uk.politics.mics, because likely the
information will be assessed differently,
and a general don't believe everything you can read
or take everything at face value.
>
I can be corrected, but 0.1% is very very low
for any generator.

 
For an in depth look at nuclear rockets of all kinds as well as things
like energy weapons, space war, ship designs, etc.,  both real and
sci fi, see:
 
https://projectrho.com/public_html/rocket/torchships.php
 
Crackpots beware, contains mathematics.
 
 

I think I misread what the 0.1% was about, it's the percentage
of usable fuel in the total fuel load.  So that figure may be
correct. The 60km/second figure is still very low, on the same
order as chemical rockets.
 
Approach it by the number of Joules in a KG of lighly
enriched uranium?
 
One thing Wikipedia isn't mentioning is jettisoning the
spent fuel to lighten the load, which would be making a material difference.
 

Obviously you did not read the links at the bottom of the wikipedia
article.

"Whatever happened to Photon Rockets?" which leads to:

https://armaghplanet.com/whatever-happened-to-photon-rockets.html

Near the end it says:

"When you closely examine the feasiblity of photon rockets the concept
falls apart. They require materials and techniques that may never exist
in the real Universe and need outrageous resources and time to attain
their amazing performance. Sadly, photon rockets appear to be forever an
intriguing fantasy."

Read the entire link to understand why that is the conclusion reached.