Getting bulky crafts into orbit

[lugge]

Ok, here's my current problem (at least, one of them :-) )

Until now, I just built "normal" rockets, with a satelitte or lander stage at the top of one or more lifter stages. Mostly, I used radial parts like rocket engines and fuel tanks. Science equipment is just placed somewhere on the final stage.

Now I'm working on a Minmus base.

I already have a skycrane out there. Consists of lots of structural parts like panels and stuff.

I'm also workin on a rover to move the segments of my station around.

And the station itself, containing habitats and towers spiked with solar panels.

Well, I have problems to get this bulky stuff into orbit.

For the skycrane, I took a big lifting stage from my Duna mission.

I removed the lander and put my skycrane atop.

It worked, but I had lots of troubles flying this craft.

I got wobbling, and my craft turned around (roll-axis) without any reasons. Also, my craft tipped over, a problem I had during my first munar missions for the last time.

Well, I finally got it up there, with no fuel left (although my skycrane is smaller in weiht than my Duna lander).

I guess this is due to the really bad aerodynamical behaviour of my skycrane.

And I guess I will have this problem with my rovers, station segments...

So, I need a solution to get this stuff up there.

I relly googled alot, and it seems there are no stock cargo parts for rockets.

Ok, for spaceplanes there are MK3 cargo bays.

But I have no experince using planes, and my tech tree is not yet finished (in fact, I don't even have the 45 points aerodynamic parts).

I know there are fairings and cargo parts for rockets in some mods, but I would like to only use stock parts.

So, what is your best practise with bulky stuff and rockets?

How do you transport stuff like skycranes, big fuel rovers...?

Greetings,

lugge

[mhoram]

So, what is your best practise with bulky stuff and rockets?

How do you transport stuff like skycranes, big fuel rovers...?

Usually I put these components into stock fairings at the top of the rocket

http://wiki.kerbalspaceprogram.com/wiki/Parts#Fairings

The are however a bit higher in the tech-tree.

For larger components strutting helps against wobbling.

Edit: For rockets that have a high drag at the top, it also helps to add wings or control surfaces at the bottom of the rocket.

Edited August 5, 2015 by mhoram

[Val]

...

Ok, for spaceplanes there are MK3 cargo bays.

...

The Mk3 cargo bays can be used on rockets too.

[Sharpy]

There are fairings for rockets in stock too. They help against drag and overheating but not against wobbling unless you strut the cargo to them. Which requires a trick: you can't draw a strut from the cargo to a fairing but you can draw it to an element outside the fairing - Kickback SRBs make good dummy parts to draw the struts to. And if it encounters a fairing along the way, it attaches to the fairing instead of the dummy outside part.

Another solution is "some assembly required" - launch the craft in a few parts forming a tube, maybe with cargo bays, and then move them around and attach to docking ports in orbit.

For example this is my nuclear tug on the launchpad (and this could have been easily split into two much more lightweight launches - one with the tug and engines, and one with the cargo bay with the drone and accessories; and not carry full fuel tanks but refuel in orbit too),

And this is the same, assembled.

[lugge]

Hello all,

thanks for your supply.

Sharpy, thanks for your pcitures, too, but I'd like to see some of your fairings crafts instead :-)

[Val]

Hello all,

thanks for your supply.

Sharpy, thanks for your pcitures, too, but I'd like to see some of your fairings crafts instead :-)

There's a short intro to Fairings here:

If that's what you were asking for?

[mrclucks]

When I launch something huge I'll have a more efficient stage directly underneath which is usually for completing orbit or transferring and then build bigger stages on the side(usually in big enough that it will cover the payload as well) and have them feed fuel into the underneath stage. If I don't have enough dv or twr I'll just continue building outwards with fuel pumping inwards

[Just Jim]

Not sure if this is what you meant, but this is the skycrane I use to haul big space stations and colony bases into orbit.

My two biggest issues are speed and overheating. The only way to get this into orbit is to stay under 300 m/s and pointed almost straight up until about 25,000 meters. 30,000 is better. If you go too fast, or attempt a gravity turn too low it will immediately tumble and explode (pretty impressive explosions, I might add.... lol)

Second issue is after 1.0.4 came out the bottom stages wanted to overheat and explode, even at 1/2 throttle. Adding radiators helped, but I can tell they're still right on the verge of blowing when I stage them.

Lastly, this skycrane will only get a station or base into low Kerbin orbit, no further. Continuing onto the Mun or wherever will require refueling first.

[Sharpy]

Fairings are only good for moderately sized payloads - they do have their size limits too after all. For larger assemblies you must work with their natural structure - see the hulls that can be integrated into rockets, make multi-rocket launch vehicles.

This is a H-shaped lifter I made. It's for lifting/landing payloads on the Mun. Landing legs, H-shape, the payload goes under the klaw in the middle. I integrated the two "bars" into the rockets, and launched it in upside-down position, with two fuel tanks/nosecones to save the worst of drag, and to keep 2.5m parts stacked tightly.

And these are two fuel trucks. I bit the bullet of the air drag by using a launch stage meant for 50% heavier payloads and only filling them with fuel halfway. The setup was too large for any fairing, even the largest, and even if it did fit, a fairing so wide would create more drag than all the exposed parts you see - it's not a cure-all solution, it has mass and drag too and sometimes these are worse than what you'd get with exposed payload.

I removed the engines by landing on the Mun at 10m/s sharp, engine down.

Alright, here's something like you requested. This payload actually is "smooth" enough that it doesn't need a fairing. The parts introduce very little drag and the fairing's mass doesn't outweigh the occlusion benefit. But it's added for a very important reason.

You see, fairings are very stiff. Like, infinitely stiff. The payload may wobble all the way out of the fairing clipping through it and breaking off, but the fairing remains perfectly vertical. That makes them awesome structural elements, especialy considering they are relatively light, can be easily discarded when no longer needed and provide the occlusion benefits.

In this screenshot you see the setup for strutting the payload to the fairings. The girders and the Kickbacks will be removed in a moment as the cargo is already firmly strutted. See the batteries just below the klaws - the struts on the right of the right battery and on the left of the left battery go to the fairing. They were made by attaching them first to the craft, and then attempting to attach them to the Kickbacks - since there was the fairing in the way, they attached to the fairing instead. Instead of three wobbly towers I have one firm fairling and the three pieces of payload nicely attached to it.

You can similarly strut things to the fairing on the outside, drawing struts to the payload, though it's a little trickier. See below.

This setup is not optimal as the kickbacks go a little too close to the fairing - they should be angled away. The trick is not to hover the cursor anywhere close to the fairing when "attaching" the ends of the struts to the Kickbacks. The fairing animation extends it as you hover over it - and unfortunately that's not just an animation. The struts would attach not to the fairing in its standard state but to the animated segments floating outside. So move that cursor away and let the fairing "settle" before attaching the ends of the struts. (actually, as you watch the left strut, they are angled sharply upwards - that's because I was "attaching" them to the upper ends of the Kickbacks, far enough from the fairing that it wouldn't expand.

(and in the end launch, strutting, fairing, all worked alright and the payload exploded into million pieces when detached, because the SavingKlaws were placed too close together, clipped into each other and disasembled explosively once they became separate crafts).

One more thing that took me a while when building a fairing. The writing changes color.

Orange means disallowed, the fairing is clipping some parts.

Green means allowed, go ahead and click.

Cyan means closing the fairing is allowed - it's either coming to a tip, or closed around a regular round element.

Grey means calculations in progress. Don't move the mouse, wait a second or two, and it will turn orange, green or cyan.

Edited August 5, 2015 by Sharpy

[Weywot8]

If you don't mind some clipping, the TT-70 "Strutty" radial decoupler will attach to suitable cargo inside the fairings while the radial attachment point remains on the outside, the fairing wall has to be between the cargo wall and the radial attachment part. You can radial decouple and blow the fairing without worry.

Also extend the tip of the fairing to a pointy end instead of closing it as soon as possible. It adds some mass but greatly reduces drag and allows more optimal ascents - savings of 300-500m/s deltaV for big payloads can make a big difference to how large the first few stages are! And after pointing it in the right direction very early on and get some good speed, the long needle-like fairing naturally steers itself into a gravity turn.

While not super large, to give an idea of how effective fairings can be, the ship below ends up in LKO with 3250m/s deltaV.

Remember to blow the fairing as early as possible to reduce weight - anywhere from 23-43 km depending on how fast the rocket is going and how 'draggy' the payload.

The proper Kerbal way is to add MOAR boosters, especially if one hasn't unlocked the largest fairing in career! Having thrusters with gimbals attached as laterally as possible and/or a really strong central gimbal thruster can save some grief. Tail fins at the end of boosters and reaction wheels at the top of the payload help alot too.

Note the sideways build to give stability - as it gets higher and faster after launch, the used boosters get dropped and drag is reduced.

Definitely MOAR boosters (4 types of engines, 1 solid fuel booster) and tail fins, radial boosters used and dropped heaviest to lightest.

Drag coef at 95'ish isn't too bad but the first rocket is only 4.5...have to get that largest fairing in career mode.

110tons on the Mun, hopping from biome to biome collecting science while drilling for ore to refuel - capable of getting to Minumus after that too. (and Duna with a slightly different design) Lands on its tail then gently tips forward with the help of RCS and the Thud rockets to slow the fall to horizontal. Launching is the reverse with the Thuds angling it up for lift-off.

Perhaps some creative skycrane decoupling + vertical to horizontal engineering for your permanent structures?