What is up with Laythe's atmosphere?

[KarateF22]

Laythe's atmosphere behaves very oddly and I do not understand why. Unlike Kerbin's atmosphere air breathing seems to be possible up to 36k with RAPIERs, yet the atmospheric height is only 50k and the pressure at sea level is well under that seen at Kerbin. The latter caused one of my recent SSTO builds to fail after I worked off a (what I believe to be reasonable) assumption that an air breathing height of 36k would mean the atmosphere would be at least equal to that of Kerbin's at sea level. Unfortunately this turned out to be false, with the atmosphere being considerably thinner... resulting in one of my SSTO builds to crash due to insufficient lift to land at a low enough speed.

Getting to the point, how much additional lift (preferably as a ratio for a given mass) should I probably expect to land horizontally on Laythe near sea level when compared to Kerbin?

[FalseKing]

It isnt much. I have an MK-1 style plane with delta wings and winglets on the delta wings, circular intake and the Whiplash jet engine. At first, it weighs 4.6 tons and has 6.72 units of lift spot on the center of lift. I do believe the ratio you're looking for is 1.4 (lift) to 1 ton.

[FalseKing]

I do believe the ratio you are looking for is 1.4 units of lift to every ton of mass.

[KarateF22]

Thats insane consider my 233 ton Refueling SSTO only requires about 25 units of lift to get into the air on Kerbin. That means I need 14 times more lift to land at a reasonable speed on Laythe? That sounds a bit too high.

[selfish_meme]

The algorithm that attenuates the atmosphere was redone to help balance Kerbin. The other planets affected by it have not been fixed yet, this is why it is so hard to aerobrake currently. On Jool there is about 500m between not aerobraking, aerobraking and instant death. I wouldn't count on their atmospheres staying like this and Jets and Rapiers will probably stop air breathing at 10-15km on Laythe.

Also: Use chutes.

[KarateF22]

The algorithm that attenuates the atmosphere was redone to help balance Kerbin. The other planets affected by it have not been fixed yet, this is why it is so hard to aerobrake currently. On Jool there is about 500m between not aerobraking, aerobraking and instant death. I wouldn't count on their atmospheres staying like this and Jets and Rapiers will probably stop air breathing at 10-15km on Laythe.

Also: Use chutes.

I guess chutes are always an option, I just preferred to have my refueling SSTO be unmanned; chutes would necessitate crew if I want this thing to be reusable. Even with chutes to make landing easy takeoffs are still nailbaiting, seems there is a 50/50 success rate even with strutted large landing gears to absorb the shock.

[BlueCanary]

I guess this could be kind of explained if Laythe was meant to have a much higher oxygen concentration than Kerbin, so jets could work even at much lower pressures. I think selfish_meme is right though.

- - - Updated - - -

Maybe since Laythe has much less gravity than Kerbin you could make it VTOL, which would help with the lack of big flat runways on Laythe. Would be kind of impractical with a 230 tonne craft though.

[KarateF22]

I did find a solution, found out that the poles of Laythe are extremely flat, allowing landings at very high speed. I guess I will just have to locate my refueling station on a polar orbit... its not that bad though considering laythe's rotational speed is only 60 m/s or so at the equator compared to Kerbin's near 200 m/s, so I am not wasting much Delta-V when you also factor in the insane efficiency of air breathing SSTOs.

[ajburges]

I did find a solution, found out that the poles of Laythe are extremely flat, allowing landings at very high speed. I guess I will just have to locate my refueling station on a polar orbit... its not that bad though considering laythe's rotational speed is only 60 m/s or so at the equator compared to Kerbin's near 200 m/s, so I am not wasting much Delta-V when you also factor in the insane efficiency of air breathing SSTOs.

Sounds like a refueling base may be a better option than a station. When a ship arrives in polar orbit, launch a full tanker on an intercept course. Keep a fuel cell powered miner/refinery (as a claw equipped rover) on the surface.

[cantab]

Laythe sea level is about equivalent to 3 km up on Kerbin, and you'll be helped by Laythe's weaker gravity too, so if you have a plane that can land at that altitude on Kerbin you should be fine landing it on Laythe. There is a somewhat flat area in the mountains west of KSC you might test at.

If you have refuelling infrastructure on the surface you could use STOVL operation, ie make the plane able to VTOL when empty but not when full, the lift engines will still reduce the takeoff/landing speeds when fully laden.