Feedtube Rockets & Other Wacked Out Ideas

[Questioner]

Feedtube Rockets & Other Wacked Out Ideas


Feedtube Rockets

One would have two fuel feed tubes hanging down from orbit to the payload.
The rocket would use fuel as needed to lift the payload, but not be lifting essentially any rocket fuel.

Real problems
1) Feedtubes that can withstand all that vertical fed pressure. [seqenced valves?]
2) Feedtubes that are strong enough to carry the miles of their own & the fuels's weight.
3) Some kind of geosynched orbital body to operate from


Stair Stepped Orbital Bodies

If one has a massive orbital body for a slow & low orbit it wouldn't need to be quite as massive if another massive orbital body obited synchronously with it, outside of it.

One could have a whole stack of them all at the same speed just with varying amounts of vector energy driving them forward in orbit their orbits.


Space Elevator Construction Logistics

More 'pragmatically' [loose use of the term] to facilitate getting a massive object in its correct orbit one will need large amounts of freefall rocket fuel.

 

[Questioner]

Personal caution

Doing things that could affect Earth's orbit or rotation is really really something to be very careful about.

 

[Questioner]

Feedtube Rockets

If one had a stream of tubed hydrogen could one pull enough oxygen out of the low Earth atmosphere fast enough to create sufficient steady firing at least enough to lift a payload?

An oxygen filter on the surface of the payload capsule?

O2 weighs many times what H2 does.

At some altitude an O2 stream would become necessary.

Pressurized valves could work like bicycle valves, only opening when the pressure was low enough to allow more fluid in.

 

[billslugg]

Personal caution

Doing things that could affect Earth's orbit or rotation is really really something to be very careful about.

I wonder how much energy is contained in the rotation of the Earth? We would need to extract a certain amount to cause a problem, but how much could be tolerated?

Just as an aside, if we slowed the Earth down 14.2% we could eliminate Mondays. just sayin'

 

[Questioner]

Mondays would be gone, but all the other work days would be longer.

Maybe we should just haul the Moon back closer to put it back in geosynchronity.

Details are fuzzy.

Scary ideas. No magic aliens to repair any screw ups we make.

"Save me Mr. Wizard,
........ from myself."

 

[billslugg]

Moment of inertia of a uniform sphere = 2/5 M r^2
Mass of Earth is 6E24 kg.
Radius of Earth = 6.4E6 m.
I = 2/5 * 6E24 * (6.4E6)^2 = 9.8E37 kg-m^2
Rotational kinetic energy = 1/2 * I * omega^2
Omega is revolutions per second which equals 1.1E-5 s^-1
Energy of rotation of Earth = 1/2 * 9.8E37 * (1.1E-5)^2 = 6E27 joules

The entire world uses 14,800 million tons of oil worth of energy each year. A ton of oil has 42 gigajoules or 4.2E10 joules
The world uses 6E20 joules per year.
If the world got all its energy by slowing down the Earth, it would take 9.6 million years to bring it to a stop. I think we're in pretty good shape.

 

[Questioner]

Maybe we could speed up the Earth's rotation.
If a day was 90 minutes we could geosynch with the space station.

If a day was 20 minutes long maybe an orbiting skyhook could be geosynchronous?

Not sure at what speed we will need seatbelts.

"Who's driving this planet anyway?"

"Look Ma, 67,000 mph around the Sun without a seat belt & no hands, too!"

 

[Questioner]

A Moon's moon & skyhooks

If one could put an object/moon in orbit around a planet then put an object in orbit around that moon in the same direction of a shared plane,
then there would be time periods when the moon's moon traveled more slowly in relation to the planets surface.

If a cable on the tidally locked moon's moon extended outward from the moon it would travel near the surface of the planet moving more slowly than than the moon.

The cable could dip in near the planet's surface with a speed approaching geosynchronity.

The timing would have to be coordinated.

It could be one had a skyhook that used the near gravity of the moon's moon, but wasn't actually attached to it.

So its cable/tail would sweep near [on?] the planet's surface,
The connection would be made with the payload.

Then using the skyhook's own fuel & possibly leveraging the mass field of the moon's moon somewhat it would lift and guide the payload to its desired orbit.

Not sure if this holds up to close scrutiny/physics, but it might have possibilities.

 

[Questioner]

A Moon's moon & skyhooks (cont )

It could be the skyhook was in an opposite orbit of the moon's moon,
Slowing the cable end relationship to the planet's surface near to zero.

 

[Questioner]

Maybe simpler,

The skyhook orbits the moon in the same direction with the tail/cable out that leaves the skyhook behind unmoving in trailing virtual freefall where its planet kissing end picks up the payload and deadlifts it into orbit?

Could that work?

Could one have a skyhook orbit [really a one time flyby] with its tail swinging around kissing the Earth and the skyhook is temporarily just hanging in freefall for a deadlift tow of the payload into planetary orbit.

The radius span's cable end has to kiss [close to geosynchronous speed] into/onto the planet's surface with excess for hooking up the payload & about that time the skyhook begins to become subject to the planets gravity it deadlifts the payload into orbit.

Space monkeys win every time.

 

[Questioner]

Maybe it is the skyhook coasting/rolling in [possibly rocket asisted] at about geosynchronous speed & direction in a tangent of orbit where its cable tail kisses the planet's surface long enough for payload hook up and then the skyhook deadlifts everything into orbit.

The skyhook is probably deadlifting itself while the hook up is taking place then it increases the rockets for a slow acceleration payload and all into orbit.

Those are going to have to be some major rocket engines on the rocket frame. It's still going to take huge reaction mass to lift even the payload and skyhook assembly & fuel,
all without frying the cable.

There would need to be shielding around the cable.

 

[Questioner]

I would think launching with the Moon overhead would save some rocket fuel.

 

[Questioner]

A freefall rocket doesn't have to be cylindrical.
In fact an approximate sphereoid woud have the most stable center of mass.
Not sure how one designs the fuel tanks to keep that uniform distribution of mass as the fuel is consumed.

It could be that some eccentricity of shape/mass is useful for articulating which rockets to use for [re-]direction.