SpaceX rocket explodes on Pad 40

[Pimander]

It looks like Elon Musk thinks the opposite, according to this.
(look for the paragraph about horizontal air launches.

This is something I'd like to take longer to look at.  I think there is a lot of in the box thinking on it.  A balloon can reach very high altitude on very little fuel.

We need space lifts.

The Pegasus is an air launched rocket.  It is small payload though...  http://www.astronautix.com/p/pegasus.html

[spacemaverick]

Do they? Which ones?
If I'm not mistaken, to reach orbit any object must reach escape velocity, which, for Earth, is 11.2 km/s (around 40,000 km/h). Escape velocity changes with the mass of the planet (Earth, in this case) and the distance between its centre and the object trying to escape its gravity, so getting a ship on the back of an airplane would give it a little help, both in speed and altitude, but not by much.

PS: escape velocity is independent of the mass of the object trying to enter orbit.

DARPA thinks they can do it.

[spacemaverick]

Using negative imaging...just get past the music



Internal rupture?

[ArMaP]

DARPA thinks they can do it.

Or not.

DARPA Scraps Plan To Launch Small Sats from F-15 Fighter Jet - See more at: http://spacenews.com/darpa-airborne-launcher-effort-falters/#sthash.LFlvvWLI.dpuf

[Pimander]

How about reusable helium "tanks" to reach very high altitude safely, then fire a stage that can also land like a plane when little fuel is required to reach orbit?

Its safe and easier to use helium than oxygen tanks.

So effectively a reusable airship stage then a reusable orbiter/lander stage.

[Pimander]

Sorry, missed that post.

Do they? Which ones?
If I'm not mistaken, to reach orbit any object must reach escape velocity, which, for Earth, is 11.2 km/s (around 40,000 km/h)

This is what I mean about in-the-box thinking.  That figure is a rocket science based idea and does not apply to higher altitude launches.

Why can't an object escape gravity at a lower speed?  If you were at very high altitude launching from an airship what happens?

Misconceptions

Planetary or lunar escape velocity is sometimes misunderstood to be the speed a powered vehicle (such as a rocket) must reach to leave orbit; however, this is not the case, as the quoted number is typically the surface escape velocity, and vehicles never achieve that speed direct from the surface. This surface escape velocity is the speed required for an object to leave the planet if the object is simply projected from the surface of the planet and then left without any more kinetic energy input: In practice the vehicle's propulsion system will continue to provide energy after it has left the surface.

In fact a vehicle can leave the Earth's gravity at any speed. At higher altitude, the local escape velocity is lower. But at the instant the propulsion stops, the vehicle can only escape if its speed is greater than or equal to the local escape velocity at that position. At sufficiently high altitude this speed can approach 0.

http://www.newworldencyclopedia.org/entry/Escape_velocity (highlights mine)

Because the gravitational pull of an object has an inverse square relationship to distance the altitude of launch has a big influence on the energy required to reach LEO.

[ArMaP]

This is what I mean about in-the-box thinking.  That figure is a rocket science based idea and does not apply to higher altitude launches.

It does, you just have to use the correct distance to the centre of mass of the planet.

Why can't an object escape gravity at a lower speed?

It can.

At sufficiently high altitude this speed can approach 0

Yes, but how high is that altitude?

We can use the formula posted on that site to make the calculations.


At the Earth's surface:
Universal gravitational constant - G=6.67×10^?11 m³ kg^?1 s^?2
Planet's mass - M=5.97237×10²⁴ kg
Radius of the planet - r=6,371.0 km
v_e=11182.72 m/s = 11.182 km/s

At 10 km from above Earth's surface we add 10 km to r and we get:
v_e=11173.95 m/s = 11.173 km/s

At 1.000 km from above Earth's surface we add 1.000 km to r and we get:
v_e=10396.52 m/s = 10.396 km/s

At 10.000 km from above Earth's surface we add 10.000 km to r and we get:
v_e=6976.11 m/s = 6.976 km/s

At 1.000.000.000 km from above Earth's surface we add 1.000.000.000 km to r and we get:
v_e=889.75 m/s = 0.889 km/s = 3200 km/h

That last velocity is much better, but how do we get the ship up to 1.000.000.000 km?

[Pimander]

That last velocity is much better, but how do we get the ship up to 1.000.000.000 km?

It isn't that simple.  You need less fuel to escape at high altitude because you don't need huge fuel tanks to get up there of course and you don't have to travel as far.  That is why the largest tank is jettisoned inside the atmosphere on the shuttle surely.

Furthermore, there is very little resistance from the atmosphere to acceleration at high altitudes.

[Pimander]

You can also accelerate horizontally first from very high altitude so you don't have to fight gravity to reach high velocity which, again, reduces the fuel requirement.

[ArMaP]

You need less fuel to escape at high altitude because you don't need huge fuel tanks to get up there of course and you don't have to travel as far.  That is why the largest tank is jettisoned inside the atmosphere on the shuttle surely.

True, but that doesn't change the escape velocity.

Furthermore, there is very little resistance from the atmosphere to acceleration at high altitudes.

See above.

[ArMaP]

You can also accelerate horizontally first from very high altitude so you don't have to fight gravity to reach high velocity which, again, reduces the fuel requirement.

See the first part of my previous post.

[zorgon]

You can also accelerate horizontally first from very high altitude so you don't have to fight gravity to reach high velocity which, again, reduces the fuel requirement.

WHY...


...can't they just use the Anti gravity tech we know they have from the Aloiens?

[spacemaverick]

That was funny Zorgon.....I haven't seen any anti-gravity saucers or anything like that...heard a lot of speculation.  I know we have the black projects but we are still messing with rockets.  I find that we are still in low earth orbit.  I would like to think we have gone far beyond rockets but alas anti-gravity seems so far away.  Maybe I have become a skeptic over time.  We seem to have departed from wondering what was behind the explosion.  I don't think it was a UFO due to the one picture or should I say video that was shown up close where I saw wings flapping.  In the negative image I saw what appeared to be a change in the rocket skin and I suspect a ruptured coupling.....the area is right next to a wildlife refuge believe it or not and we have many large birds here.

[Pimander]

See the first part of my previous post.

Do you think its a bad idea to launch from high altitude after lifting with helium then?  I genuinely thin the idea is a good one.

WHY...


...can't they just use the Anti gravity tech we know they have from the Aloiens?

Gravitic doesn't necessarily imply anti-gravity.

Apparently it would take an act of God to get that one out of the bag.  It nearly destroyed our site/group last time we even considered it. 

[Pimander]

  I know we have the black projects but we are still messing with rockets.  I find that we are still in low earth orbit.  I would like to think we have gone far beyond rockets but alas anti-gravity seems so far away. 

As Ben Rich said, who developed the stealth aircraft back in 1993 in the presence of two friends of mine: "We now have the technology to go to the stars". And that was back in 1993.' When Mr Good was asked to elaborate on where this technology came from, he replied: 'Alien crafts. The study of alien crafts that have been recovered and by liaising with actual aliens who have helped us develop this technology. https://en.wikipedia.org/wiki/Talk%3ABen_Rich

True?  Why would he lie when he was about to die?