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Engineering360: "Soaring through space on solar sails"

05/25/2020 9:25 AM

Read Engineering360 article: Soaring through space on solar sails.

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Guru

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#1

Re: Soaring through space on solar sails

05/26/2020 7:30 AM

"...state of-the-art chemical rocket engines and by the amount of fuel a spacecraft must carry, which can add up to 25% of the launch weight of typical planetary-exploration spacecraft. ..."

.

25% ?!? Ha!

Would that it were! Propellant alone without the mass of the engines is typically not too far off 85% of launch mass even for just low Earth orbit.

Surely the 25% figure is a typo, right?

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#2

Re: Soaring through space on solar sails

06/11/2020 10:24 AM

Re 25% weight savings

As I read the article I understood perhaps incorrectly the 25% weight figure was related to amount of fuel and engines required for maneuverability of craft after deployment and not the weight associated with lift off. % figures depend on what your base value is. Saving 25% on weight after deployment could result in more or better instrumentation on board.

Gshaiffer

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#3
In reply to #2

Re: Soaring through space on solar sails

06/11/2020 2:14 PM

"... Space exploration missions have been limited by the performance margins of state of-the-art chemical rocket engines and by the amount of fuel a spacecraft must carry, which can add up to 25% of the launch weight of typical planetary-exploration spacecraft. ...."

.

To me, 'launch weight' rather unambiguously describes weight at lift off.

Perhaps I am reading that completely wrong somehow. If anyone can confirm I am in error, especially with some reference I would be appreciative.

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#4
In reply to #3

Re: Soaring through space on solar sails

06/11/2020 2:36 PM

add up to 25% of the launch weight of typical planetary-exploration spacecraft. ...."

Not trying to be a smart alec,and my english scores were not that great but the above phrase is what I am seeing. the terms 25% of the launch weight of typical planetary space craft does not seem to me to be describing the launch weight of the entire vehicle stack but only the launch weight of the craft going to orbit.If the basic craft weighed 2000 lbs 500 lbs of that would be engine and orbiting propellant mass, this says nothing about the weight of the total launch assembly as I read this.

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#5
In reply to #4

Re: Soaring through space on solar sails

06/11/2020 3:00 PM

That would certainly make more sense. It may be a bit convoluted, and certainly leas than clear from my vantage, but given that what I read is so far off base realistically, you probably are on point with what was intended.

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