Problem New system - surface gravity much stronger

[RobN]

I have made my own fictional solar system and I was pretty proud of it until I tried to take off in a Shuttle-A from my Earth-like planet. I couldn't. The surface gravity was 1.7 MN! This on a planet that is very similar in size and mass to the Earth. Strange.

So, I made another planet very similar to our moon and found the same problem - the surface gravity is around twice what it should be.

Finally I decided to add a copy of Mars to my system and found the same problem even with that.

I am at a loss and would appreciate any help.

 

[asbjos]

It would help if we could look at the config files for your planets.

 

[RobN]

OK. Here is the file for my Earth-like planet.

; === Configuration file for planet Enn ===
Name = Enn
EllipticOrbit = TRUE
HasElements = TRUE

; === Planetary Mean Orbits ===
Epoch = 2000.0 ; J2000
SemiMajorAxis = 9.9e10 ; meters
Eccentricity = 0.00005
Inclination = 0 ; rad
LongAscNode = 0.86530876153 ; rad
LongPerihelion = 5.8650190805 ; rad
MeanLongitude = 6.20383077256 ; rad

; === Physical Parameters ===
Mass = 5.2018542e24
Size = 6.37992e6 ; mean radius


; === Rotation Elements ===
SidRotPeriod = 88642.6632 ; 24.622962 hours
SidRotOffset = -0.757 ; by Chode - determined from the sun rise and
; set times for Spirit and Opportunity
Obliquity = 0.0063 ; obliquity of ecliptic (26.72°)
LAN = 4.5865 ; longitude of solar transit (262.78°)

; === Atmospheric Parameters ===
AtmPressure0 = 101.4e3 ; pressure at zero altitude [Pa] (defined via module)
AtmDensity0 = 1.293 ; density at zero altitude [kg/m^3]
AtmGasConstant = 286.91 ; specific gas constant [J/(K kg)]
AtmGamma = 1.4 ; specific heat ratio c_p/c_v
AtmAltLimit = 200e3 ; cutoff altitude [m]
AtmAttenuationAlt = 100e3; ; cutoff altitude for light attenuation
AtmHorizonAlt = 64e3 ; horizon rendering altitude [m]
AtmHazeExtent = 0.14 ; horizon haze extent
AtmColor0 = 0.6 0.8 1.01
AtmHazeColor = 0.8 0.8 0.83
AtmFogParam = 5e-5 3e-5 4e3
AtmFogColor = 0.55 0.85 1.10

; === Cloud parameters ===
CloudAlt = 7e3 ; altitude of cloud layer
CloudRotPeriod = 1e6
CloudShadowDepth = 0.3
CloudMicrotextureAlt = 35e3 300e3

; === Visualisation Parameters ===
MaxPatchResolution = 10 ; highest sphere patch level
MinCloudResolution = 1 ; cloud layer from this resolution
MaxCloudResolution = 8 ; highest cloud resolution level

BEGIN_SURFBASE
DIR Enn\Base
END_SURFBASE

 

[BrianJ]

....I tried to take off in a Shuttle-A from my Earth-like planet. I couldn't. The surface gravity was 1.7 MN! ....

Hi,
is it possible you are misinterpreting the Visual Helpers->Forces->Weight display?
It shows the total force acting on the vessel due to gravity.
The acceleration due to gravity at the surface of your planet Enn is ~8.52m/s^2, mass of Shuttle-A is about 207200kg, total force will be:
8.52 x 207200 = 1765344N = ~1.765MN

Why you can't take off - I don't know!
EDIT: Yes I do! - the Shuttle-A hover engines give 1.355MN, not enough to lift off witth a full fuel load from Earth or Enn. I'm not a Shuttle-A user, so don't know if there is a fix for this.

Hope this helps.
Cheers,
BrianJ

 

[martins]

Note that a fully loaded Shuttle-A can't take off from Earth with hover engines alone either. They produce 1.356MN of lift. You need the auxiliary pods in vertical (hover) position to assist, which should give a total of 2.056MN lift at ground level (Earth). More in vacuum.

 

[RobN]

Problem solved. It was nothing to do with the system and its planets and everything to do with the scenario file. For some unearthly () reason the scenario file had given my Shuttle-A a PAYLOAD MASS = 120000. There is a rational explanation for everything.

Oops.

:blush: