Why Landers?

[Corw]

How do i find out the weight of the fuel in my main ship?

Note the mass of a ship, empty tanks in VAB, note new mass. Difference is fuel. Or get a mod.

[AbacusWizard]

How do i find out the weight of the fuel in my main ship?

Check the Resources panel in the toolbar. Add together the numbers shown for Liquid Fuel and Oxidizer (this tells you the volume of fuel) and then multiply the result by 5 (the density). This should tell you the mass in kg. (If you want tonnes, divide by 1000.)

[Perry Apsis]

In the Kerbol system, I think it makes more sense on bigger bodies that are further away in delta V from Kerbin.

For Eve, I think it's pretty much a requirement to have a separate lander.

My 0.9 Eve mission used a single launch (with a refueling stop) direct mission profile (no separate lander) to get to the planet and back up into orbit, but required a rendezvous with a return vessel to get back. I'm reasonably confident it would have taken less total tonnage if I had expanded the lower stages to include the return vehicle, but I was really pushing the limits in terms of parts already. It would have required extra boosters to get to orbit as well. It was also far, far heavier than anything I've ever launched. But if I were concerned about money I'd have gone with an Apollo-style profile, if the game would handle it.

[abowl]

Note the mass of a ship, empty tanks in VAB, note new mass. Difference is fuel. Or get a mod.

Is there a mod that you would suggest?

[NecroBones]

Is there a mod that you would suggest?

Both KER (Kerbal Engineer Redux) and MechJeb will provide you with numbers. I like them both.

Another thing you can do for "back of the envelope" estimates, is that the LF and Oxidizers both weigh 0.005 tons per unit.

[Superfluous J]

Yes you waste fuel, however the science payoff of doing it early, before rcs and docking ports is significant. My way was to have lander with four outriger drop tanks where top stage had 4 legs so it could be used independently. this also held material lab, goo, batteries and other stuff on other side, the two other outriger tanks was dropped then empty, then 4 tanks below who was dropped then empty or before landing.

With this I did all biomes on Minmus except poles, did the uneven terrain first before dropping first outrigger

The Jr docking port is an early unlock now (one of my favorite parts of the new tech tree) and I don't need RCS to dock, especially small ships

I got 4500 or so science from Minmus after (IIRC) 2 mun landings, which up to that point was my only real science gain.

[Temeter]

People do this because they want to make Apollo-style mission. You're right it's very inefficient in stock system.

So you wondering why NASA did it in real life. This is very easy to explain. In real life Moon is 10 times bigger than Mun so you need ~1600m/s to make descent/ascent instead of ~700m/s, also you need 800m/s if you want go back to Earth from low Moon orbit (300m/s in stock system). With much bigger delta V numbers Apollo-style landings will be more efficient.

I'm using Real Solar System mod and I can tell you that Direct style with CSM will need to build 50% heavier rocket than Saturn V.

Wait, you're telling me my RSS two stage 6k D/V moon lander is too big? I mean, the apollo moon landing maneuver wasn't even very efficient.^^'

I went for real apollo engines and just checked for a fitting thrust/weight ratio, so I guess moon lander engines and saturn 5 are just ridiculously overpowered for what they're supposed to do?

[Mister Kerman]

I got 4500 or so science from Minmus after (IIRC) 2 mun landings, which up to that point was my only real science gain.

I did that recently too.

A few good trips to Minmus can almost clear the Tech Tree.

[G'th]

Wait, you're telling me my RSS two stage 6k D/V moon lander is too big? I mean, the apollo moon landing maneuver wasn't even very efficient.^^'

I went for real apollo engines and just checked for a fitting thrust/weight ratio, so I guess moon lander engines and saturn 5 are just ridiculously overpowered for what they're supposed to do?

They're not necessarily overpowered, its just that you aren't using up the safety margins. Real manned craft don't only carry fuel for the exact dV they need for their mission. Indeed, when it comes to real rockets and spacecraft, efficiency trades off for safety. While yes, there could have been some potentially large savings, fact of the matter is in order to make those savings worth it you'd have to guarantee that every maneuver from Launch to splash down would be performed perfectly.

[wumpus]

They're not necessarily overpowered' date=' its just that you aren't using up the safety margins. Real manned craft don't only carry fuel for the exact dV they need for their mission. Indeed, when it comes to real rockets and spacecraft, efficiency trades off for safety. While yes, there could have been some potentially large savings, fact of the matter is in order to make those savings worth it you'd have to guarantee that every maneuver from Launch to splash down would be performed perfectly.[/quote']

There is also the issue that KSP engines are fully throttleable. Very few rockets are throttleable (the Lunar excursion module being the exception, and certainly only the descent engine). I'm fairly sure there is either no or little throttle on the lunar command module's engine (note that it wasn't designed to restart. I've heard claims that "engineers" weren't too afraid of restarting the engine for Apollo 13, but if it wasn't in the spec, it probably was never tested. If it was never tested I'd be scared silly of relying on an untested feature). Even the "highly throttleable" merlin engine used by SpaceX can't be throttled down enough to do anything other than a suicide burn on one engine during landing.

[NecroBones]

There is also the issue that KSP engines are fully throttleable. Very few rockets are throttleable (the Lunar excursion module being the exception, and certainly only the descent engine). I'm fairly sure there is either no or little throttle on the lunar command module's engine (note that it wasn't designed to restart. I've heard claims that "engineers" weren't too afraid of restarting the engine for Apollo 13, but if it wasn't in the spec, it probably was never tested. If it was never tested I'd be scared silly of relying on an untested feature). Even the "highly throttleable" merlin engine used by SpaceX can't be throttled down enough to do anything other than a suicide burn on one engine during landing.

Actually the service module engine was capable of multiple restarts. Part of the problem during Apollo 13 is that the command module was powered down, and the lunar module was being used as a lifeboat. They ended up using the lander's descent engine for multiple maneuvers to preserve what remained of the service module.

But yes, the Apollo mission is a very notable exception. Since the LM and the CSM engines were to be used for multiple maneuvers each, they both could restart.

[Alshain]

I like landers because I seem to plan better that way. It's sort of a delta-V dividing line. In fact I like LEM style landers that leave behind the legs and landing engines for the same reason. I always end up under-planning with an all-in-one, but if the fuel tanks are separated by phases of the mission it just makes it easier.

[rodion_herrera]

Well I just discovered that all my "Apollo-style" stacks in v1.0.4 (built in v1.x.x) now seem "overbuilt". It used to be that I would require some boost from the third stage (as it was with the real Saturn V) before reaching a good LKO from which to perform a trans-Munar injection burn, but today, after patching to v1.0.4, I still had a nearly full tank for my third stage, when before it used to have burned off about a third for circularization. I now feel that v1.0.3/v1.0.4's Kerbin atmosphere is a much more forgiving one.

And I don't know whether to be happy or disappointed

[Mister Kerman]

Have you got a picture of the lander inside that fairing? =3

[rodion_herrera]

Have you got a picture of the lander inside that fairing? =3

Not right now, but I can describe it easily. It's basically just a 2-man lander with an X200-8 Fuel Tank slapped underneath for ascent, and another X200-8 with a Poodle for descent.

[Araym]

Take a 2.5m Pod. Add 2.5m Heatshield. Add a 2.5m decoupler. Add 2 Material Bay, 4 Goo pod, 4x every smaller Science Experiment(5 experiments). Build with a 2.5m fairing a perfect cilinder to cover ALL of the science parts.

Now you can add ONLY INSIDE the 2.5m fairing cilinder some fuel. NO TANKS could be outside. Both Oxidizer and Liquid Fuel, as well any extra Monopropellent you could need for RCS, aside the one in the Pod.

THAT, kerbalized, are the requirement to build a "sort of REAL Apollo CSM"..........

........ "a lot of electronics and science experiments" (in real life, just only taking pictures was NEEDED for science, not counting tons of phisical data of the enviroments around a spaceship in space every launch), with ONLY spare space for fuel........

It's very different from add just a 2.5m fuel tank and a Poddle engine, under the decoupler......

[rodion_herrera]

Have you got a picture of the lander inside that fairing? =3

Managed to squeeze in some time to actually take snaps now.

And oh, sorry, wasn't a Poodle but a Terrier for the descent stage.

[Mister Kerman]

Ah. Seems about right. I like Apollo landers/CSM for single landings. I'm just about ready in my career to leave Kerbin's SOI and start visiting other planets. I'll be doing my missions Apollo-style. Possibly bring some extra dock-descent stages instead of decoupler-style.