Better than asparagus staging?

[700NitroXpress]

I'm using an air lift method to get any sized payload into space in two stages. Then, once in space, I can send up any engine I want and dock it to the rest of the craft using the same launch method.

Here is an image of my Atlas III craft with the launch stage attached to it. You can also check out the video demo of this method here:

The download link is in the descriptions. Fly it like I did and you'll have no problem.

What do you pro's think of this method?

What do you new players think of this method?

Here is better example of this method. Air lift to max altitude, burn orbital engines, decouple, attach new transfer engines through docking process.

Don't just look at the air lifter. What do you guys think about the engine refit with the use of the docking ports? You can attach any engine or fuel amount you want in orbit without having to refuel the system.

Edited November 8, 2013 by 700NitroXpress

[Jordanpumah]

jets are for planes.

it seems every couple of updates, people find this new "cheaty" way to get stuff into space.

I'm so old fashioned.

[PDCWolf]

Mostly depends on what you call "better".

Think about it this way:

•Is your system cheap?

•Are you using durable techniques? (As in something that may be still useful after an aerodynamics update for example)

•Are the parts you are using considered OP? (NERVAs, Turbojets)

•Are the parts you are using going to remain the same during updates?

•Are you using techniques considered cheaty? (Air-hogging, intake stacking)

•Does your lifter look good?

•What's the maximum payload to LKO?

•Can you make a cheaper system with the same payload capacity?

•Can you make a system with the same capacity but with less parts?

Edit: I forgot some important ones.

•Are you using mods?

•Are you using mods that are considered "OP" or "unrealistic" or "unbalanced" ?

That's what defines a good lifter for me.

Edited October 26, 2013 by PDCWolf

[700NitroXpress]

Technically, it's not cheaty because it's just a large scale version of this:

[Kasuha]

Looking at the size of the payload you got up, I consider my lifter simpler and more powerful.

But of course jet engines can be used very efficiently to lift stuff at the edge of the atmosphere.

Edited October 26, 2013 by Kasuha

[Simon Ross]

I actually quite like it :-)

In honesty, any method that gets you above the first 20km of soup is a valid method. Only thing I did notice on the video was there was still an awful lot of jet fuel left at separation, maybe still some headroom for optimisation there.

[numerobis]

Jets use a lot less mass, but a lot more parts and are more finicky. So it depends what you are optimizing for.

You're using engine nacelles, which have horrid drag. I'd recommend against that; use something to attach your jets to; a truss piece works well and is much lighter. And indeed, you tend not to need much fuel at all, so you can skimp a lot on fuel.

You can fly higher than you did, given that the engines went *up* when you decoupled them. Turbojets are better at high speed and altitude. You could launch, drop the lower set of basic jets at ~10-15 km, then ride the turbojets up to 20-25km. Also, turn rather than going straight up; use the jets to build up horizontal speed.

The caps on your rockets are a waste of mass.

Edited October 26, 2013 by numerobis

[PDCWolf]

Technically, it's not cheaty because it's just a large scale version of this:

Yeah, but KSP's turbojets are incredibly op and don't work like real life counterparts at all.

[700NitroXpress]

Yeah, but KSP's turbojets are incredibly op and don't work like real life counterparts at all.

[700NitroXpress]

Jets use a lot less mass, but a lot more parts and are more finicky. So it depends what you are optimizing for.

You're using engine nacelles, which have horrid drag. I'd recommend against that; use something to attach your jets to; a truss piece works well and is much lighter. And indeed, you tend not to need much fuel at all, so you can skimp a lot on fuel.

You can fly higher than you did, given that the engines went *up* when you decoupled them. Turbojets are better at high speed and altitude. You could launch, drop the lower set of basic jets at ~10-15 km, then ride the turbojets up to 20-25km. Also, turn rather than going straight up; use the jets to build up horizontal speed.

The caps on your rockets are a waste of mass.

Good advice for optimization, thanks.

[700NitroXpress]

I was only doing a simple version for the purposes of demo. I used the same method to get my Duna Command Center into orbit as well as this.

https://docs.google.com/file/d/0B-vTRL2n8wvzaVkxMTNwUlNsMVU/edit?usp=drive_web

[PDCWolf]

Yeah, the P&W J58 outputs 110kN when dry. Weights 3.7 tonnes and has a TWR of 6.

KSP's TurboJet Engine outputs 150kN without afterburner, weights 1.2 tonnes and has a TWR of 30.

[Kasuha]

I think it's pointless to discuss differences between KSP and real hardware. Nothing in KSP works like real hardware.

[Seret]

The caps on your rockets are a waste of mass.

Check the 0.22 changelog, nose cones do improve stability in atmo now.

[PDCWolf]

I think it's pointless to discuss differences between KSP and real hardware. Nothing in KSP works like real hardware.

It makes sense. Rocket engines were scaled to fit the atmospheric model and have low ISPs because of that, to be balanced with the game. They are underpowered in terms of real life. Turbojets and the normal jet engine were not scaled and are incredibly overpowered, even for their real life counterparts.

Also, I made a mistake. TurboJets' TWR is about 12, which is still a freaking lot. On top of that you can just airhog them to make them work pretty high up, which is a bit of a shady technique if you ask me.

Edited October 26, 2013 by PDCWolf

[numerobis]

Check the 0.22 changelog, nose cones do improve stability in atmo now.

It's such a tiny effect: the nose cone has 0.03 mass, so it barely moves the center of mass at all, and it has fixed drag.

Instead you can add a tail fin or a winglet at the back of your rocket to get a strong deflection force when your rocket starts pointing off the path, one that increases as you get further off the path. The winglet also gives you control input. And these parts are lighter than the nose cone.

Or, you can just dump them all, save the mass and drag, and use gimballing engines (such as basic jets) and reaction wheels instead.

[Kasuha]

Okay, I gave it a shot and changed my lifter to use jet engines instead of its two outermost stages. The result was the following contraption. It did about the same job (notice the orange tank is the cargo, none of its fuel is used), it was unbelievably funny to fly, but it also required way more attention - I needed to watch intake air all the time and drop unnecessary engines several times.

It was kinda fun. But I am going to stick to my original lifter. This is too much of a Rube Goldberg device.

Javascript is disabled. View full album

[cfds]

Using jets as the initial stage for an orange tank lift can look surprisingly elegant:

In 10km height I shut down half the jet engines and in 14km the whole thing switches to rocket power.

[Rhomphaia]

That is a lot of engines for such a tiny payload.

[700NitroXpress]

Using jets as the initial stage for an orange tank lift can look surprisingly elegant:

In 10km height I shut down half the jet engines and in 14km the whole thing switches to rocket power.

This is pretty cool. They should work up to 20km before you switch to the rockets.

Edited October 27, 2013 by 700NitroXpress

[Sirrobert]

That is a lot of engines for such a tiny payload.

They are however very efficient

[Rhomphaia]

They are however very efficient

Not so much. The mass of all those engines and the limited choice of optimal fuel tanks is a bit of a killer

Here is a simple asparagus that can lift the same payload into orbit for 300 less liquid fuel.

Basically just a beefed up version of the rocket stage, so the jets really were not helping much.

Edited October 27, 2013 by Rhomphaia

[700NitroXpress]

Try combining the two methods then. Use this and the jet engines.

[700NitroXpress]

I posted up a better example next to the demo image. It's the launch stage for the Duna Command Center. All of the jet engines are fueled through the large fuel tank so they don't use separate fuel. When you eject the jet engines, all of them shut down because they don't have their own fuel supply so no fuel is wasted. Then you burn powerful rockets to achieve orbital height. The next stage has the 215 power rockets to finish the orbit with fuel to spare to achieve perfect orbit and adjust inclination. You then decouple the engines and refit them with the nuclear engines and it goes all the way to Duna. Then the nuclear engines are ejected upon de-orbit burn. Landing engines and parachutes take over, and the entire base lands in one piece.

[Dispatcher]

It depends on the situation. Sometimes I combine turbos with asparagus and solid boosters. When I do so, I'll use turbos on an upper stage in conjunction with the first stage rocket and boosters because they seem to do less damage to the craft than a rocket does. I use small rocket fuel tanks for the jets so that they run out of fuel just before they run out of oxygen. They seem more stable than when allowing them to have a traditional flame out; at least that's been my experience.