XPost: rec.arts.sf.misc
From: chakatfirepaw@gmail.com
On Wed, 05 Aug 2015 20:21:52 +0000, Bernard Peek wrote:
> On 2015-08-05, Rick Pikul/Chakat Firepaw
> wrote:
>
>> Here's a hint for you: When a drive uses electrical power, how big of
>> a generator you need is a very important factor. Replacing 20 tonnes
>> of propellant with a 30 tonne reactor is not a good trade.
>
> It could be if the 30 tonne generator can deliver more delta-V.
In that case it isn't replacing 20 tonnes of propellant, it's replacing
more than 20 tonnes. At some point, the extra mass of the reactor is
less than amount of propellant and tankage needed for the same
performance.
> We know that there is a theoretical limit on the delta-V that a reaction
> drive carrying its own propellant can deliver. Do the same limits apply
> if the generator/engine combination does not use any propellant?
Note: This is all about me describing the best case scenario for the EM
Drive scam being that is is a poor example of a known type of reaction
drive.
If you can source all the fuel and propellant you need from outside, then
yes there is no limit on how much deltaV you have. However, there may be
other limitations on performance. Solar sails can only get so fast
before they quickly fly too far away from the star they are using,
magsails have the same issue. Bussard ramjets, (assuming you could fix
the reasons they probably won't work at all), can't go faster then their
exhaust velocity, (relative to the interstellar medium).
> I think in practice the most likely configuration would be an externally
> powered first stage to accelerate the payload then an internally powered
> stage to decelerate at the other end.
Assuming you had a drive that would do better than a laser sail.
--
Chakat Firepaw - Inventor and Scientist (mad)
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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