Re: How big would an SSTO be?


"Sylvia Else" <sylvia@xxxxxxxxxxxxxxxxxxx> wrote in message
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Jeff Findley wrote:
"Sylvia Else" <sylvia@xxxxxxxxxxxxxxxxxxx> wrote in message
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Still, the craft has to be in balance during reentry, when the fuels
have presumably been used up. The centre of lift has to be where the
centre of gravity is then.

This isn't correct.

Strictly speaking the lift vector has to pass through the centre of mass.

Strictly speaking, when your center of gravity is the same as your center of
pressure, you've got neutral stability. This is not normally done with
aircraft since it's usually desirable for an aircraft to be stable. That
is, if you take your hands and feet off the controls, the craft will
continue to fly in a stable orientation.

Last time I checked (15 years ago when I was still getting my aerospace
engineering degree), you want your center of gravity to be in front of your
center of pressure in order for an aircraft to be stable. On top of that,
aircraft (the shuttle orbiter included) generally have an acceptable range
for their center of gravity location.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)


.

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