spaceship designs why not wider

[Vist]

Hi everybody,

I've recently designed and landed a big mining ship (using 50% B9 parts) on a slightly inclined terrain on Mun with x2 re-scaled landing legs. For the first few minutes, the ship swayed a bit before being stable. Made sure that it didn't wobble when all the drills were active and switched scenes to and from the ship a few times. :">

I used my ever faithful Mun rover to scout the terrain in the... East Crater It's there in the first place because most of the resources are present. :">

Now I thought that if the ship was wider, it wouldn't wobble even on a inclined surface (not too inclined).

What's the disadvantage of designing wide spaceships?

Regards and thanks for your comments/feedback.

Edited September 7, 2015 by Vist

[GoSlash27]

Vist,

The main problem is in getting them into orbit from KSC. wide payloads generate a lot of drag on the ascent.

For landing and launch from the surface of airless bodies, they are ideal.

Best,

-Slashy

[bigcalm]

Wide is fantastic for landing on airless moons - as Slashy says, it's getting them into orbit off Kerbin that's the issue - expect a very ineffecient ascent profile. Here's an example (on its way to Bop and Pol, tested fine on Minmus's slopes):

[Vist]

Vist,

The main problem is in getting them into orbit from KSC. wide payloads generate a lot of drag on the ascent.

For landing and launch from the surface of airless bodies, they are ideal.

Best,

-Slashy

Wide is fantastic for landing on airless moons - as Slashy says, it's getting them into orbit off Kerbin that's the issue - expect a very ineffecient ascent profile. Here's an example (on its way to Bop and Pol, tested fine on Minmus's slopes):

http://i.imgur.com/sW6z3Ry.png

Hi guys, thanks for pointing out increase in drag and the example vessel. should have known :">

Guess the next best thing for wide ships is to divide them and assemble in orbit.

Thanks again.

[Sharpy]

Note the assembly doesn't need to be all that hard and complex if you launch the lander *sideways*.

Below is not a lander but another ship that is very wide, a tug with two engines on two ends.

So you can launch a lander of "X" shape profile with longer beam going along the launcher axis and the shorter either sticking sideways or attached at a later time, in orbit.

[Mikki]

Usually you need a real overpovered liftervehicle, asparagus staging and lots of boosters. Ascend slowly, its not really efficient but you want to put a big thing up...

Throttle up slowly, to much TWR kills your rocket, make it top-heavy against flipping, make a cautious gravityturn...

[cantab]

Yeah, getting them into space in the first place. I find that my payload should not be significantly wider than my launcher or I'll have stability problems. A wide launcher for a wide payload is an obvious option though it might be overpowered in thrust and dV terms. Otherwise big fins on the rocket's core stage help.

Launching the lander "sideways" is indeed a good way to get a large but low profile lander that's easier to launch, but designing such a lander can be trickier. RCS Build Aid will help a lot along with good use of the offset tool. Such landers can be a bit trickier to fly too, since they'll turn much more easily in some directions than others, it's nothing major but takes a little getting used to.

[Kelderek]

If your vessel is really wide and has a lot of drag then it may be necessary to use an inefficient (but safer) vertical launch with less of a gravity turn and a larger circularization burn once in space.

[Kryxal]

If the payload is all that wide, I'm likely to use a multi-stack launcher, and strut the stacks together.

[Hagen von Tronje]

A middle ground option is to "cheat" width by using girders or I-beams, possibly buttressed by struts, to place your legs far out from your lander core. This will still create additional drag on launch and you will still have to compensate for that, but it will be far less than if you designed the whole lander to be a pancake.

An example:

Sorry it's a bit dark, shot was taken in on the Mun's north pole in a place with very little light, ever. But you can see it's landed on a really severe slope, and zooming in at the bottom of the tanks should show you the legs on the end of girders, giving it a much wider base without increasing drag cost all that much.

However it's also worth noting that to this day I don't gravity turn Munshots, I wait until the right time of day and launch straight up, then make a correction burn if really needed. This is mostly because it takes a fraction of the flight time to execute and I'm lazy like that, but it has the nice side effect of minimizing the time you spend experiencing drag at all, so you have some flexibility in what you put up.

[Clipperride]

I've been using the standard Mk2 parts to make a wide drill and associated bits. The way I did it was;

- Use a vertical rocket rather than space plane.

- Build a rocket so the first stage has low acceleration. (I'm happy with ~300m/s at 10,000m)

- Assend vertically to 10km then slowly pitch over to around 45° East.

- Switch to map view and fine tune your angle of attack so your Apo marker stays about the same distance in front of you.

- Once horizontal you can burn until Apo is about 100km. Then coast up and circularise.

- Heavy payloads have the advantage of pushing your CoM further forward. Think of a bomb or dart with its weighted nose.

Although it's a very expensive way of doing things, I've launched some really odd shaped payloads with the above launch profile. The first 10km of the atmosphere is what is going to give the biggest drag and control issues.

Another way to go is with Senior docking ports and some assembly required. Have fun :-)

[Vist]

Note the assembly doesn't need to be all that hard and complex if you launch the lander *sideways*..

Usually you need a real overpovered liftervehicle, asparagus staging and lots of boosters. Ascend slowly, its not really efficient but you want to put a big thing up...

Throttle up slowly, to much TWR kills your rocket, make it top-heavy against flipping, make a cautious gravityturn...

Yeah, getting them into space in the first place. I find that my payload should not be significantly wider than my launcher or I'll have stability problems. A wide launcher for a wide payload is an obvious option though it might be overpowered in thrust and dV terms. Otherwise big fins on the rocket's core stage help.

Launching the lander "sideways" is indeed a good way to get a large but low profile lander that's easier to launch, but designing such a lander can be trickier. RCS Build Aid will help a lot along with good use of the offset tool. Such landers can be a bit trickier to fly too, since they'll turn much more easily in some directions than others, it's nothing major but takes a little getting used to.

If your vessel is really wide and has a lot of drag then it may be necessary to use an inefficient (but safer) vertical launch with less of a gravity turn and a larger circularization burn once in space.

If the payload is all that wide, I'm likely to use a multi-stack launcher, and strut the stacks together.

A middle ground option is to "cheat" width by using girders or I-beams, possibly buttressed by struts, to place your legs far out from your lander core. This will still create additional drag on launch and you will still have to compensate for that, but it will be far less than if you designed the whole lander to be a pancake...

I've been using the standard Mk2 parts to make a wide drill and associated bits. The way I did it was;

- Use a vertical rocket rather than space plane.

- Build a rocket so the first stage has low acceleration. (I'm happy with ~300m/s at 10,000m)

- Assend vertically to 10km then slowly pitch over to around 45° East.

- Switch to map view and fine tune your angle of attack so your Apo marker stays about the same distance in front of you.

- Once horizontal you can burn until Apo is about 100km. Then coast up and circularise.

- Heavy payloads have the advantage of pushing your CoM further forward. Think of a bomb or dart with its weighted nose.

Although it's a very expensive way of doing things, I've launched some really odd shaped payloads with the above launch profile. The first 10km of the atmosphere is what is going to give the biggest drag and control issues.

Another way to go is with Senior docking ports and some assembly required. Have fun :-)

Interesting tips and ships/landers guys =) will come up with my own design... right after I get the tech node for the MKS/OKS refinery. Sorely need it for refining on Mun to generate funds. :">

Am thinking of having lifting capabilities on major drag points and fairings above it to further reduce drag.

Tried assembling a multi-part lander/ship in sandbox mode and had a difficult time aligning them during docking phases because I wanted the RCSs to be aligned as well.

[xendelaar]

I build my miner landers as a streamlined rover/space plane. I put the whole mining rig on a set of wheels and lift the vehicle vertically from Kerbin, so drag is hardly an issue . On any given moon, I land the miner on its wheels so it doesn't matter if I'm on a slope. I normally use the airplane wheels, which have those cool 100% energy efficient lights XD. Landing on airplane wheels also has the benefit that you can save some delta V (30-50 m/s)by landing with some remaining velocity. Use can use the brakes to dissipate the energy. This is, of course, not relevant for mining rigs with an ore converter, since you have an unlimited supply of fuel if you land on the right spot...

- - - Updated - - -

However.. lifting off (from the moon) does require some extra torque from reaction wheels, since the engine is oriented horizontally (assuming you've landed on a flat area)

[Ripper2900]

A little trick I've used in a couple of landers, is to use the heavy landing legs, and rotate them a click or two outwards. Granted, it doesn't look really super, and when retracted, they'll be partly inside. But - they'll have a much better reach and provide you with a much larger footprint for increased stability.

[Vist]

I build my miner landers as a streamlined rover/space plane. I put the whole mining rig on a set of wheels and lift the vehicle vertically from Kerbin, so drag is hardly an issue . On any given moon, I land the miner on its wheels so it doesn't matter if I'm on a slope. I normally use the airplane wheels, which have those cool 100% energy efficient lights XD. Landing on airplane wheels also has the benefit that you can save some delta V (30-50 m/s)by landing with some remaining velocity. Use can use the brakes to dissipate the energy. This is, of course, not relevant for mining rigs with an ore converter, since you have an unlimited supply of fuel if you land on the right spot...

- - - Updated - - -

However.. lifting off (from the moon) does require some extra torque from reaction wheels, since the engine is oriented horizontally (assuming you've landed on a flat area)

Hmmm...space plane... am allergic to those :">

A little trick I've used in a couple of landers, is to use the heavy landing legs, and rotate them a click or two outwards. Granted, it doesn't look really super, and when retracted, they'll be partly inside. But - they'll have a much better reach and provide you with a much larger footprint for increased stability.

This gave me an idea will attach heavy landing legs on an appropriate B9 winglet on both sides with the same 1 lick rotated position.

> Am thinking of having lifting capabilities on major drag points and fairings above it to further reduce drag.

Haven't had much luck on the design I mentioned above being cost effective :"> Got carried away playing too much on sandbox mode. D