Thrust/speed ratios in MegaTraveller

A thread of 2 messages, 20 November 1992 to 23 November 1992, in the order they were sent.

#4964 Thrust/speed ratios in MegaTraveller

Does it matter? · 20 November 1992

Someone was complaining earlier (I don't remember who, I had to recycle
  the posting, and I could be confusing it with the archives I've been
  reading, but....) that the thrust/speed chart in the design
  sequence is inaccurate for modern aircraft.  I just realized why.

In the design sequence, it is assumed that a vessel will have to defeat
  1G of gravity in order to begin moving.  Basically, this ignores
  the concepts of aerodynamics.  For vertical take off and landing,
  a craft is capable of doing without a 1+ G of acceleration.
  This is what taxiing was developed to avoid, and means that
  anyone trying to design a grav-bike or other vessel doesn't have
  to use so much power to produce thrust, thus producing cheaper
  and smaller vessels.

To correct this, the easiest (though probably not realistic) method
  would be to stop subtracting 1 from the Gs of acceleration
  produced by the vessel if it is intended for atmospheric use.
  Of course, in less dense atmospheres, or higher gravity worlds,
  the speed or taxiing time would have to be adjusted.  Unfortunately,
  I'm only an amatuer physicist, so someone else will have to work
  out the exact adjustments.

On planets without atmospheres, the standard 1G loss of effective
  thrust would still apply.
Just my few bytes worth,
- --Brad

#4982 Thrust, and non-silicon chips

Adrian Hurt · 23 November 1992 · reply to #4964

"Does it matter?" [email removed] writes:
>
> In the design sequence, it is assumed that a vessel will have to defeat
>   1G of gravity in order to begin moving.  Basically, this ignores
>   the concepts of aerodynamics.
> ...
> To correct this, the easiest (though probably not realistic) method
>   would be to stop subtracting 1 from the Gs of acceleration
>   produced by the vessel if it is intended for atmospheric use.
>   Of course, in less dense atmospheres, or higher gravity worlds,
>   the speed or taxiing time would have to be adjusted.
> ...
> On planets without atmospheres, the standard 1G loss of effective
>   thrust would still apply.

If we're going to start making corrections for different atmosphere types,
shouldn't we also correct for different planet sizes?  I assume that 1G loss
is used up fighting gravity and keeping the vehicle off the ground - except
that it will need more or less than 1G for that purpose, on worlds larger or
smaller than Earth respectively.

[email removed] writes:
>
> A couple points:
> Hans points out that the obvious defence to the silicon
> predators viruses is have non silicon chips.
>
> Well, guess what?  He's absolutely right.
> As a matter of fact, I'd say a computer with silicon chips may
> be common now, but supercomputers, (especially ones in the future)
> will use silicon as the EXCEPTION not the rule.

Alright, so the virus eats whatever is the common type of chip.  Using
silicon chips is the way to beat the virus, although this does limit the
TL of your computers.  And this, I believe, was the whole point in the
first place.

> Believe me, having traveller computers on silicon chips is kinda like
> saying the starships are powered by fuel injected V-8 engines.  If
> That were the case, then Lucan's supervirus should eat all the
> petrochemicals in the galaxy and everybody waits forever at the gas
> pumps...  :-)

Or in my scenario, the supervirus eats all the deuterium, and everyone
has to use fuel-injected V-8 engines. :->

>...
> The average scoutship weighs in at 1000 + metric tons.  I don't have my
> books with me, but I believe thats around twice the weight of a fully
> loaded B-52.  Yet it has about the same wing area of an F-4 Phantom.
> Will it fly?  No.  It just can't get enough lift from air alone.

I can just imagine an SF RPG in 1918, where someone proposes an aircraft
that will fly more than twice the speed of sound, stay up using wings,
and have a wing area of 179 square feet.  And someone else says that even
if it didn't fall apart from trying to go faster than sound, which is of
course impossible, this aircraft has less than 80% of the wing area of a
Sopwith Camel, yet weighs almost 10 times as much empty as the Camel weighs
fully loaded.  No way will it fly.

40 years later the first person says "Told you!" as a Lockheed F-104 flies
past. :-)

- --
 "Keyboard?  How quaint!" - M. Scott

 Adrian Hurt     |JANET:  [email removed]
 UUCP: ..!uknet!cee.hw.ac.uk!adrian  |  ARPA:  [email removed]