Whose fault is this?

[Mad Rocket Scientist]

Alright, who stole my booster:mad:

Really, though, this is a real lifter design. The Atlas V 412 has only SRB:

So how does this work? Tell us your theories here!

[Kryten]

TVC keeps engine pointed through the centre of mass. The soviet Energiya rocket was considerably more asymmetric and kept stable through the same mechanism; if you watch launch videos, you can see it tip over for about a second before the gimbals kick in.

[Armchair Rocket Scientist]

Alright, who stole my booster:mad:

http://i.imgur.com/oVBY6j4.png

Really, though, this is a real lifter design. The Atlas V 412 has only SRB:

http://www.spaceflightnow.com/atlas/av008/launch/a09.jpg

So how does this work? Tell us your theories here!

Basically, the RD-180 has 8 degrees of gimbal range, compared to maybe 1 degree for whatever engines you put on that thing.

[Mad Rocket Scientist]

TVC keeps engine pointed through the centre of mass. The soviet Energiya rocket was considerably more asymmetric and kept stable through the same mechanism; if you watch launch videos, you can see it tip over for about a second before the gimbals kick in.

Interesting!

Basically, the RD-180 has 8 degrees of gimbal range, compared to maybe 1 degree for whatever engines you put on that thing.

Actually it works fine, it just seems inefficient.

[RainDreamer]

If you look at it in a certain way, the space shuttle fly similarly, with the whole shuttle a sort of booster on the side of a huge tank.

[vger]

Doesn't really seem that weird to me. In fact it sort of makes sense since the final objective is to get a vehicle that is flying horizontally, not vertically. Whether or not it's more efficient though?

I would think that you could achieve orbit with less use of controls, using such a setup. But then it needs gimbals just to get off the ground, so... what's the point? Saving on metal to build a second booster?

[sgt_flyer]

Well, it saves on commonality you can configure the booster to use more or less SRBs depending on what you need to put your payload into orbit - and you don't need to specially design and use a smaller booster to have symmetry (as it's SRBs, it would have been half the length of the current one, same diameter to use 2x SRBs instead of 1 (for the same thrust & firing duration) - which would have also required a modification of the rocket's core stage - so it could be mated with those 'small' SRBs.

So it's mainly about economics no need to have separate production lines / tooling for a special version of the booster

[Bill Phil]

It's called gimbal range. The RD-180 has a decent one.

[Lime]

I know why the RD-180 gimbals

[Sidereus]

I think the bigger question is...why does your fairing look like a mushroom?

[Nuke]

i want to know what that thing has under its composite panels

[Sidereus]

Alright, who stole my booster:mad:

http://i.imgur.com/oVBY6j4.png

Really, though, this is a real lifter design. The Atlas V 412 has only SRB:

http://www.spaceflightnow.com/atlas/av008/launch/a09.jpg

So how does this work? Tell us your theories here!

Minor nitpick:

I was curious about the Atlas V 412, so I tried to hunt down some info on it. It turns out the 412 configuration has never flown. That's probably a 411. From what I can find, there have been three 411 launches, and zero 412 launches.

Anyway, the way the rocket is designated is kind of interesting. The first number designates the diameter of the payload fairing in meters (it can be either 4 or 5 meters), the second digit is the number of SRBs (up to 3 with a 4m fairing, and up to 5 for a 5m fairing), and the third is the number of engines on the Centaur stage (up to 2). https://en.wikipedia.org/wiki/Atlas_V#Variants

511 and 512 variants are also possible, but haven't been flown either. A fourth 411 is planned to be launched in 2016 and will carry the New Frontiers 3 OSIRIS-REx spacecraft, followed by three in 2017 to send up GPS and military com satellites, as well as one in 2018 to send up another GPS satellite. https://en.wikipedia.org/wiki/List_of_Atlas_launches_%282010%E2%80%9319%29

Edited May 15, 2015 by Sidereus

[Mad Rocket Scientist]

Sorry for the delay.

If you look at it in a certain way, the space shuttle fly similarly, with the whole shuttle a sort of booster on the side of a huge tank.

It is like that, isn't it.

Doesn't really seem that weird to me. In fact it sort of makes sense since the final objective is to get a vehicle that is flying horizontally, not vertically. Whether or not it's more efficient though?

I would think that you could achieve orbit with less use of controls, using such a setup. But then it needs gimbals just to get off the ground, so... what's the point? Saving on metal to build a second booster?

I guess that the Atlas can only work with Atlas boosters, it seems like you could just strap on a already produced smaller SRB.

Well, it saves on commonality you can configure the booster to use more or less SRBs depending on what you need to put your payload into orbit - and you don't need to specially design and use a smaller booster to have symmetry (as it's SRBs, it would have been half the length of the current one, same diameter to use 2x SRBs instead of 1 (for the same thrust & firing duration) - which would have also required a modification of the rocket's core stage - so it could be mated with those 'small' SRBs.

So it's mainly about economics no need to have separate production lines / tooling for a special version of the booster

That makes sense.

It's called gimbal range. The RD-180 has a decent one.

It's a good thing that the gimbals were buffed for 1.0.

I know why the RD-180 gimbals

Same as above.

I think the bigger question is...why does your fairing look like a mushroom?

Dreamchaser+no stock hinges=

i want to know what that thing has under its composite panels

Dreamchaser replica.

Minor nitpick:

I was curious about the Atlas V 412, so I tried to hunt down some info on it. It turns out the 412 configuration has never flown. That's probably a 411. From what I can find, there have been three 411 launches, and zero 412 launches.

Anyway, the way the rocket is designated is kind of interesting. The first number designates the diameter of the payload fairing in meters (it can be either 4 or 5 meters), the second digit is the number of SRBs (up to 3 with a 4m fairing, and up to 5 for a 5m fairing), and the third is the number of engines on the Centaur stage (up to 2). https://en.wikipedia.org/wiki/Atlas_V#Variants

511 and 512 variants are also possible, but haven't been flown either. A fourth 411 is planned to be launched in 2016 and will carry the New Frontiers 3 OSIRIS-REx spacecraft, followed by three in 2017 to send up GPS and military com satellites, as well as one in 2018 to send up another GPS satellite. https://en.wikipedia.org/wiki/List_of_Atlas_launches_%282010%E2%80%9319%29

True, it has not been launched, but it is the planned config for the Dreamchaser:

It could use any suitable launch vehicle but is planned to be launched on a human-rated Atlas V 412 rocket.

[Kryten]

I wouldn't really use the word 'planned' for Dreamchaser. 'Hoped' would be better.

[Mad Rocket Scientist]

I wouldn't really use the word 'planned' for Dreamchaser. 'Hoped' would be better.

"Dreamed"?

[sgt_flyer]

Yes, dreamchaser was planned to be launched on an atlas 412 - but without fairings, and fixed wings

The version of dreamchaser with foldable wings for launch within a fairing would have been for either : the cargo version, or a launch atop an ariane rocket (ESA did not want to have to do a costly recertification of their launcher to handle different aerodynamic properties)

[Mad Rocket Scientist]

Yes, dreamchaser was planned to be launched on an atlas 412 - but without fairings, and fixed wings

The version of dreamchaser with foldable wings for launch within a fairing would have been for either : the cargo version, or a launch atop an ariane rocket (ESA did not want to have to do a costly recertification of their launcher to handle different aerodynamic properties)

Ah ha! I see, well I don't want to recertificy mine.

[Woopert]

Yes, dreamchaser was planned to be launched on an atlas 412

I thought Dream Chaser was supposed to launch on Atlas V 402?

400 series, no boosters, 2 RL10 engines. Maybe they changed it later.

[sgt_flyer]

I thought Dream Chaser was supposed to launch on Atlas V 402?

400 series, no boosters, 2 RL10 engines. Maybe they changed it later.

Guess that with a 11,3 tons for the dreamchaser, they thought it was maybe too much near the upper limits for the atlas V 402 (12.5 tons to LEO in this configuration)