KSP 1.02 Thrust to Weight Way Off on Eve

[StevenLawyer]

So, I build a ship that should have a takeoff TWR from Eve of about 2.0 (about 4.0 on Kerbin). I get it to Eve, and at takeoff, it has under a 1.0--can't get off the ground. Tried it with multiple designs. Is this a bug? Any thoughts?

[Reactordrone]

Are you taking into account the higher air pressure on Eve reducing the engine's thrust below the Kerbin ASL levels?

[StevenLawyer]

I read somewhere that the Devs had revised the modeling of thrust to no longer be constant--i.e., to decrease thrust with decreased ISP due to atmosphere, but I think they have made a sea-level Eve ascent virtually impossible.

[SanderB]

If you land on the 7.5km highest peak on eve you can get reasonable TWR and dV with the 3.75m diameter engines, and thus a significant payload.

[Starhawk]

The old ISP modelled inefficiency in atmospheric pressure by increasing the fuel consumption when ISP was low. This is not how it works in reality.

So they changed the model so that it accurately reflects how rockets work. In high pressure environments, thrust is decreased. At Eve, with 5 atmospheres of pressure at sea level this results in many engines being almost, or even completely, useless.

Happy landings!

[Mister Dilsby]

So much for my dreams of ion-gliding from Eve sea level to orbit

[Captain Sierra]

So, I build a ship that should have a takeoff TWR from Eve of about 2.0 (about 4.0 on Kerbin). I get it to Eve, and at takeoff, it has under a 1.0--can't get off the ground. Tried it with multiple designs. Is this a bug? Any thoughts?

Use aerospikes. They have very high ASL Isp and a near horizontal Isp curve, so they won't get slammed by Eve's atmosphere like everything else will.

[Francesco]

Aerospikes at sea level on Eve have almost the same ISP as the Mainsail.

The problem is their low TWR.

Has someone built a return ship with 'spikes in the first stage?

[SanderB]

the 2.5m and above diameter engines have very reasonable ISP between 0.0km and 7.5km altitude.

[n0xiety]

Mamooth engines works really good on Eve tho rhinos are completely useless. Btw someone made a graph that shows engine twr against engines weight itself and seems the mamooth has the best results. So Mamooth engine gives the most twr for what it weights.

[Foxster]

Here's my Eve ship...

The return ship is this less the escape tower on the top that has the 'chutes/airbrakes and the mining/processing stuff on the bottom. ie.:

Less dV is required for seal-level to Eve orbit now. Used to be about 12K, it's now closer to 8K.

Edited May 14, 2015 by Foxster