-Z- (z@gundam.com)
Sat, 28 Oct 2000 09:55:40 -0700


> -----Original Message-----
> From: owner-gundam@1u.aeug.org [mailto:owner-gundam@1u.aeug.org]On
> Behalf Of Lim Jyue
> Sent: Saturday, October 28, 2000 08:13
> To: gundam@aeug.org
> Subject: Re: [gundam] G, Vibes & Noise (was: My Grand OYW GM
> Re-unification Idea)
>
> Eehh.. Actually, my T/W ratio meant how much thrust (in kg) 1 kg of
> deadweight will recieve under full thrust. For example, a T/W of 2.95 meant
> if the GT is reduced to a mere 1kg block, it will have a thruster array
> which can produce 2.95kg of thrust.
>
> In this sense, I don't think it *quite* means 2.95G.

Well, the AGX-04 Gerbera Tetra specs on Mecha Domain give the acceleration of
the MS, with and without booster, as 2.95 G and 3.67 G, so either your derived
mass ratio is coincidentally the same as the acceleration or someone, somewhere,
equated 1 kg of propellant per 1 kg of mass to 1 G of acceleration and gave the
mass ratio as the acceleration.
>
> >Back before we had the Space Transportation System, our astronauts were
>
> You mean, in layman's term, the Space Shuttle. =)

Well, now that we have a space station of sorts, I suppose it can now properly
be called a shutle. Until recently, it's just been a glorified orbital transfer
vehicle.

> >Negative G is less tolerable, reducing the maximum to 2 to 3 G for
> short term.
>
> For those who are interested, IIRC the reason (as discussed on this
> list about 2-3 years back) was because the human organs were designed (via
> genetics) to be more tolerant of positive G than negative G. In other words,
> if you spend too much time in too much negative Gs, your organs will detach
> themselves and make a mess of your innards.

Giving an entirely new meaning to the term "guts and glory".... (-_-)

Which does nothing to explain the popularity of suspending oneself upside down
as a means of improving one's health. On the other hand, "intoxicated" means
"poisoned" and people have been dosing themselves with various toxins both
medicinally and recreationally for ages, so I guess it just feels good in the
short term.

"The wonderful thing about hitting yourself in the head with a hammer is how
good it feels when you stop...!"

> >Vibration in the airframe is actually more problematic.
>
> How big a problem will this be for space MS? I understand the low
> frequency vibration can really make you sick -- sort of like sea-sickness,
> only that you're in the deep space -- but I suspect a bigger problem, at
> least mechanically speaking, is metal fatigue and wear and tear.

Vibration can incapacitate the pilot in a very sneaky way, but numbing or
paralyzing the hands. G force will do that, too -- one of the reasons that
pilot tolerance is in the 7 to 9 G range instead of the 10 to 15, even with
transverse alignment, is that the G force can induce a condition not unlike a
combination carpal tunnel syndrome and tennis elbow. If manual dexterity is an
issue, vibration and G force will take their toll.

Of course, a jackhammer operator has it ten times worse.

> >Noise is also a problem. Space boosters produce noise levels of 145 to 175
> >decibels.
>
> A bit OT, but didn't submariners have something called the
> Discomfort Index or something, to indicate how bad things were in the
> submarine?

Yeah, and even the space shuttle (there, I said it!) crew have problems with
noise above and beyond that produced by the engines. The air circulation system
fans and hydraulic pumps are all very noisy and that noise is transmitted
throughout the ship, as it has nowhere else to go in the vacuum of space. The
noise from the mid-deck cooling fans is considered particularly bad. Crew
members are issued blindfolds and earplugs for sleeping, as the crew cabin is
never completely quiet, but I haven't been able to find any decibel ratings for
the ambient noise.

 There's also a peculiar rumbling noise that results from the side of the ship
facing the sun heating up while the side facing away cools down -- the
equivalent of a sailing ship's hull creaking under various strains. Ocassional
pressure changes may result in a sound midway between that of a steam calliope
and a pipe organ, as various cavities and passgeways become resonating chambers.

By the way, the shuttle pulls 3 G going up and 1.5 G during re-entry. It has to
reach a speed of 28,000 KPH (17,500 MPH or about Mach 23.5) to reach low Earth
orbit (400 km or 250 miles) in about 45 minutes. The solid rocket boosters
(SRB) push you to 130 km (80 miles) and Mach 15 in six and a half minutes, with
main engine cutoff (MECO) at eight and a half and external tank (ET) discard 20
seconds after that.

-Z-

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