OhioBob

Then they must have made changes to the parachutes. All other things being equal, lower density = less drag. If parachutes are performing better in thinner air, then it's possible the area and/or drag coefficient of the parachutes has been increased.

Kerbin has the same surface gravity as Earth due to its absurdly high density. However, its gravitational parameter is only 3.5316 ×1012 m3/s2, which is 1/113th of Earth.

It's coded that way. It's based off a standard model of Earth's atmosphere. Standard atmospheres define temperature as a linear function of height to eliminate the need for numerical integration in the computation of pressure versus height.

There is in-game evidence that Laythe's atmosphere may have an ozone layer. Its atmosphere contains a layer where the temperature increases with increasing altitude, comparable to Earth's stratosphere. The reason for this in Earth's atmosphere is that ozone absorbs UV energy. The same could be happening at Laythe.

I haven't attempted a Duna landing since v1.0, but, based on the numbers, I don't believe that's the case. Duna's atmosphere at high altitudes is denser that it use to be, but at low altitudes it is less dense. Landing at an elevation <3000 m should be the same or more difficult than previous versions. I estimate that to get a vehicle to descend at the same terminal velocity on Duna that it would have on Kerbin requires about 2.5 times the parachute area. Below is a graph comparing the old and new atmospheric density of Duna.

The equations I provide in the post referenced above estimate temperature and pressure pretty well. Another way to calculate it is to use the equations of the U.S. Standard Atmosphere (USSA), given below: [TABLE=class: grid, width: 750] [TR] [TD=bgcolor: transparent, colspan: 3] U.S. Standard Atmosphere, 0 to 86 km [/TD] [/TR] [TR] [TD=bgcolor: transparent] Geopotential Altitude, h (km') [/TD] [TD=bgcolor: transparent] Molecular-Scale Temperature, TM (K) [/TD] [TD=bgcolor: transparent] Pressure, P (Pa) [/TD] [/TR] [TR] [TD=bgcolor: transparent] 0-11 [/TD] [TD=bgcolor: transparent] 288.15 – 6.5 × h [/TD] [TD=bgcolor: transparent] 101325.0 × [288.15 / (288.15 – 6.5 × h)] (34.1632 / –6.5) [/TD] [/TR] [TR] [TD=bgcolor: transparent] 11-20 [/TD] [TD=bgcolor: transparent] 216.65 [/TD] [TD=bgcolor: transparent] 22632.06 × EXP[–34.1632 × (h – 11) / 216.65] [/TD] [/TR] [TR] [TD=bgcolor: transparent] 20-32 [/TD] [TD=bgcolor: transparent] 196.65 + h [/TD] [TD=bgcolor: transparent] 5474.889 × [216.65 / (216.65 + (h – 20))] (34.1632) [/TD] [/TR] [TR] [TD=bgcolor: transparent] 32-47 [/TD] [TD=bgcolor: transparent] 139.05 + 2.8 × h [/TD] [TD=bgcolor: transparent] 868.0187 × [228.65 / (228.65 + 2.8 × (h – 32))] (34.1632 / 2.8) [/TD] [/TR] [TR] [TD=bgcolor: transparent] 47-51 [/TD] [TD=bgcolor: transparent] 270.65 [/TD] [TD=bgcolor: transparent] 110.9063 × EXP[–34.1632 × (h – 47) / 270.65] [/TD] [/TR] [TR] [TD=bgcolor: transparent] 51-71 [/TD] [TD=bgcolor: transparent] 413.45 – 2.8 × h [/TD] [TD=bgcolor: transparent] 66.93887 × [270.65 / (270.65 – 2.8 × (h – 51))] (34.1632 / –2.8) [/TD] [/TR] [TR] [TD=bgcolor: transparent] 71-84.852 [/TD] [TD=bgcolor: transparent] 356.65 – 2.0 × h [/TD] [TD=bgcolor: transparent] 3.956420 × [214.65 / (214.65 – 2 × (h – 71))] (34.1632 / –2) [/TD] [/TR] [TR] [TD=bgcolor: transparent, colspan: 3] Density, à(kg/m3) = P/(RTM) Speed of sound, C (m/s) = (γRTM)1/2 Specific gas constant, R = 287.053 J/kg-K Specific heat ratio, γ = 1.400 [/TD] [/TR] [/TABLE] As has been explained, Kerbin's atmosphere is based on the USSA with the vertical height scale reduced 20%. In addition, the USSA uses geopotential height, h, rather than geometric height, z. Therefore, two conversions must be made. First, the geometric height used in KSP has to be multiplied by 1.25 to undo the 20% reduction, and then the result must be converted to geopotential height. This can be done in a single step using the following equation: h = 7963.75*z / (6371 + 1.25*z) Once h is calculated, the temperature, pressure, density, and speed of sound can be obtained using the equations in the table above. The above method isn't exact but it will get you pretty close. The temperature equations are right on the money, but this is "base" temperature. The actual ambient air temperature at any location on Kerbin varies based on latitude and time of day. The pressure equations are very accurate at low altitudes, however some error starts to appear at higher altitudes. This is because the floatCurves used in KSP are only an approximation of the USSA. Furthermore, above z = 63.2 km (h = 78 km) the pressure equation breaks down because Kerbin's atmospheric pressure is forced to converge to zero at z = 70 km. If you find the equations in the post reference by Cybersol easier to use, then use those. I post the above mainly so you can see the origin of the numbers used in KSP.

Duna's atmosphere has changed significantly from v0.90. Datum level pressure has not changed, but the rate of pressure drop with increasing altitude is much less. The game also now calculates density as a function of pressure, temperature, and molecular weight, unlike before when it was simply a function of pressure. At low altitudes the density of Duna air is less than pre-1.0; however, at high altitudes it is much greater. At the datum level, Duna air is about half as dense as before, at 3000 m it's about the same, and at 6000 m it's about twice as dense. By the time we get to 15000 m, the air is more the 10 times denser than v0.90.

FYI, scale height does not have a constant value as it did in pre-1.0. H = 5600 m was derived as an approximation. Using it does not yield a reliable value of the pressure at a given altitude.

Just posted this in another thread, but I'll repeat it here... Mounting an oversized part at the front does nothing to occlude parts behind, other than the attachment face. For instance, radially attached parts produce the same drag whether they are fully exposed to the airstream or whether they are partially tucked in behind an oversized fairing or nose cone. Placing a 2.5m nose cone on a 1.25m attachment point is bad because the larger nose cone only increases the drag surface area while providing no other benefit. The large nose cone also adds mass, so it's doubly bad.

Mounting an oversized part at the front does nothing to occlude parts behind, other than the attachment face. For instance, radially attached parts produce the same drag whether they are fully exposed to the airstream or whether they are partially tucked in behind an oversized fairing or nose cone. Placing a 2.5m nose cone on a 1.25m attachment point is bad because the larger nose cone only increases the drag surface area while providing no other benefit. The large nose cone also adds mass, so it's doubly bad.

Yes, but with the new aero it is rather involved and requires inputs that are not easily obtained. Your are probably better off determining it experimentally.

I would be interesting to see how these results compare with the drag coefficients for all these parts. All other things being equal, the one with the lowest drag coefficient should go highest and fastest. The drag coefficients are found in PartDatabase.cfg. Here is an example: PART { url = Squad/Parts/Command/mk1Cockpit/mk1Cockpit/Mark1Cockpit DRAG_CUBE { cube = Default, 1.823583,0.7348939,0.8693516, 1.823583,0.7353885,0.9128191, 1.263023,0.2716523,2.393878, 1.263023,0.9475985,0.3517535, 2.053816,0.7649878,0.7245554, 2.053816,0.7311577,0.7189386, -4.053116E-06,0.9747789,-0.00202769, 1.383462,2.291587,1.23226 } } The eighth number is the drag coefficient for the Y+ face, which is the face that would be facing the air stream in a normal configuration. In the above case, the drag coefficient for the Mk1 Cockpit is 0.2716523. Below are the drag coefficients for parts that might be mounted at the front end of a rocket. [TABLE=width: 375] [TR] [TD=width: 239, bgcolor: transparent]Mk1 Cockpit[/TD] [TD=width: 74, bgcolor: transparent, align: right]0.2716523[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk2 Cockpit[/TD] [TD=bgcolor: transparent, align: right]0.2005389[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk3 Cockpit[/TD] [TD=bgcolor: transparent, align: right]0.4265045[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk1 Command Pod[/TD] [TD=bgcolor: transparent, align: right]0.4787524[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk1-2 Command Pod[/TD] [TD=bgcolor: transparent, align: right]0.5247738[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk1 Lander Can[/TD] [TD=bgcolor: transparent, align: right]0.9474164[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk2 Lander Can[/TD] [TD=bgcolor: transparent, align: right]0.9399109[/TD] [/TR] [TR] [TD=bgcolor: transparent]PPD-12 Cupola Module[/TD] [TD=bgcolor: transparent, align: right]0.8409463[/TD] [/TR] [TR] [TD=bgcolor: transparent]Stayputnik Mk. 1[/TD] [TD=bgcolor: transparent, align: right]0.4507724[/TD] [/TR] [TR] [TD=bgcolor: transparent]Launch Escape System[/TD] [TD=bgcolor: transparent, align: right]0.5314794[/TD] [/TR] [TR] [TD=bgcolor: transparent]CH-J3 Fly-By-Wire Avionics Hub[/TD] [TD=bgcolor: transparent, align: right]0.4088397[/TD] [/TR] [TR] [TD=bgcolor: transparent]Circular Intake[/TD] [TD=bgcolor: transparent, align: right]0.4500000[/TD] [/TR] [TR] [TD=bgcolor: transparent]Ram Air Intake[/TD] [TD=bgcolor: transparent, align: right]0.4454349[/TD] [/TR] [TR] [TD=bgcolor: transparent]Shock Cone Intake[/TD] [TD=bgcolor: transparent, align: right]0.3000000[/TD] [/TR] [TR] [TD=bgcolor: transparent]Small Nose Cone[/TD] [TD=bgcolor: transparent, align: right]0.4011730[/TD] [/TR] [TR] [TD=bgcolor: transparent]Aerodynamic Nose Cone[/TD] [TD=bgcolor: transparent, align: right]0.6305804[/TD] [/TR] [TR] [TD=bgcolor: transparent]Advanced Nose Cone - Type A[/TD] [TD=bgcolor: transparent, align: right]0.3476872[/TD] [/TR] [TR] [TD=bgcolor: transparent]Advanced Nose Cone - Type B[/TD] [TD=bgcolor: transparent, align: right]0.4535100[/TD] [/TR] [TR] [TD=bgcolor: transparent]Protective Rocket Nose Cone Mk7[/TD] [TD=bgcolor: transparent, align: right]0.5857430[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk16 Parachute[/TD] [TD=bgcolor: transparent, align: right]0.6422904[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk16-XL Parachute[/TD] [TD=bgcolor: transparent, align: right]0.7324356[/TD] [/TR] [TR] [TD=bgcolor: transparent]Mk25 Parachute[/TD] [TD=bgcolor: transparent, align: right]0.7803856[/TD] [/TR] [TR] [TD=bgcolor: transparent]Clamp-O-Tron Docking Port Jr.[/TD] [TD=bgcolor: transparent, align: right]0.9203191[/TD] [/TR] [TR] [TD=bgcolor: transparent]Clamp-O-Tron Docking Port[/TD] [TD=bgcolor: transparent, align: right]0.9149400[/TD] [/TR] [TR] [TD=bgcolor: transparent]Clamp-O-Tron Shielded Docking Port[/TD] [TD=bgcolor: transparent, align: right]0.8379832[/TD] [/TR] [TR] [TD=bgcolor: transparent]Clamp-O-Tron Docking Port Sr.[/TD] [TD=bgcolor: transparent, align: right]0.9563304[/TD] [/TR] [TR] [TD=bgcolor: transparent]Advanced Grabbing Unit[/TD] [TD=bgcolor: transparent, align: right]0.6949234[/TD] [/TR] [/TABLE]

Yes, the density of Duna air at 30 km is indeed greater than Kerbin air at 40 km. At 40 km on Kerbin, the air pressure is 78.89 Pa. Temperature varies, but over the equator it is about 275 K at this altitude. The mean molecular weight of Kerbin air is 28.9644 g/mol. These give us a density of 0.0009994 kg/m3. At 30 km on Duna, the air pressure is 108.0 Pa. The temperature at this altitude is 150 K. The mean molecular weight of Duna air is 14 g/mol. These give us a density of 0.001212 kg/m3. Duna's atmosphere is actually composed of lighter gases, having a mean molecular weight of 14 g/mol. In real life this doesn't make sense. A small terrestrial planet like Duna could never retain the lightweight gases needed to lower the molecular weight to 14. BTW, in just the last couple of days I revised the atmosphere section of each planet's Wiki article. There is now a table for each planet that gives the pressure at various altitudes. Some of you might find that information useful.

The following should help, Orbital Mechanics There may be more in that page then you need, but you can always skim through it until you find the parts that interests you. There are sample problems that show how to compute a wide variety of orbital maneuvers. If there is anything you don't understand, don't hesitate to ask specific questions.

^^^ This thread got pretty detailed in discussing how drag is computed. For the atmospheric properties of Kerbin, try this >>> http://forum.kerbalspaceprogram.com/threads/117069-Great-New-Physics-Thread%21?p=1940443&viewfull=1#post1940443

Yes, I did some testing on that and got similar results to yours. I tried one example in which the height-to-radius ratio of the conical part was 1:1 (half cone angle of 45o), and another example in which the ratio was 2:1 (half cone angle of 26.565o). My rocket's drag coefficient was about 20% less using the higher ratio (i.e. pointier).

You have to treat each portion of the burn as a separate stage, compute the ÃŽâ€v separately for each stage, and then add up the results. For example, let's say you have a liquid core with SRB strap-ons: A = total initial mass B = mass of solid propellant C = dry mass of SRBs D = mass of liquid propellant t1 = burn time of SRBs t2 = burn time of liquid core (where t2>t1) For the first stage, Initial mass = A Final mass = A - B - D*t1/t2 For the second stage, Initial mass = A - B - C - D*t1/t2 Final mass = A - B - C - D The above assumes you're not adjusting the throttle so that the propellant flow rate of the liquid engine is constant. The Isp is not a simple average (or even a weighted average). When you have different engines operating at the same time, the combined ISP is Isp = ΣF / Σ(F/Isp) Let's say you have one engine with a thrust of 1000 kN and an Isp of 250 s, and another with a thrust of 500 kN and an Isp of 300 s. The combined Isp is Isp = (1000+500) / ((1000/250)+(500/300)) = 264.71 s

There is no longer a simple equation to calculate pressure as there was pre-1.0. I talk about it in the following post: http://forum.kerbalspaceprogram.com/threads/117069-Great-New-Physics-Thread%21?p=1940443&viewfull=1#post1940443 The following will provide a very close approximation that will suit most purposes. The pressure is accurate to within 0.5% for altitudes below 62.3 km, and much closer than that in most cases. Above 62.3 km it is accurate to within 2%. [TABLE=class: grid, width: 1000, align: center] [TR] [TD=colspan: 3, align: center]Kerbin Standard Atmosphere, 0 to 70 km[/TD] [/TR] [TR] [TD=align: center]Geometric Altitude, z (km)[/TD] [TD=align: center]Kinetic Temperature, T (K)[/TD] [TD=align: center]Pressure, P (Pa)[/TD] [/TR] [TR] [TD=align: center]0-8.815[/TD] [TD=align: center]288.15 – 8.11117 × z[/TD] [TD=align: center]EXP[ –5.6684193E-05 × z3 – 1.9580663E-03 × z2 – 0.14836114 × z + 11.5260885 ][/TD] [/TR] [TR] [TD=align: center]8.815-16.050[/TD] [TD=align: center]216.65[/TD] [TD=align: center]EXP[ 3.6215104E-06 × z3 – 1.1135486E-04 × z2 – 0.19514262 × z + 11.753405 ][/TD] [/TR] [TR] [TD=align: center]16.050-25.729[/TD] [TD=align: center]196.7513 + 1.23980 × z[/TD] [TD=align: center]EXP[ 1.8765033E-06 × z3 + 4.0682342E-04 × z2 – 0.21018261 × z + 11.868445 ][/TD] [/TR] [TR] [TD=align: center]25.729-37.879[/TD] [TD=align: center]139.7102 + 3.45679 × z[/TD] [TD=align: center]EXP[ –4.1690244E-05 × z3 + 5.0761226E-03 × z2 – 0.36509550 × z + 13.508117 ][/TD] [/TR] [TR] [TD=align: center]37.879-41.129[/TD] [TD=align: center]270.65[/TD] [TD=align: center]EXP[ –3.6083972E-04 × z3 + 0.044146606 × z2 – 1.9496301 × z + 34.813685 ][/TD] [/TR] [TR] [TD=align: center]41.129-57.440[/TD] [TD=align: center]411.8568 – 3.43327 × z[/TD] [TD=align: center]EXP[ –8.6910710E-07 × z3 – 1.0609374E-03 × z2 – 0.062235305 × z + 8.6153226 ][/TD] [/TR] [TR] [TD=align: center]57.440-68.798[/TD] [TD=align: center]354.7555 – 2.43916 × z[/TD] [TD=align: center]See below[/TD] [/TR] [TR] [TD=align: center]68.798-70.000[/TD] [TD=align: center]186.946[/TD] [TD=align: center]See below[/TD] [/TR] [TR] [TD=align: center]57.440-62.300[/TD] [TD=align: center]See above[/TD] [TD=align: center]EXP[ 1.5412356E-05 × z3 – 3.5432535E-03 × z2 + 0.058616347 × z + 6.7777398 ][/TD] [/TR] [TR] [TD=align: center]62.300-70.000[/TD] [TD=align: center]See above[/TD] [TD=align: center]EXP[ –9.37298921E-04 × z5 + 0.304103311 × z4 – 39.4630615 × z3 + 2560.291576 × z2 – 83044.59921 × z + 1077314.96395 ][/TD] [/TR] [/TABLE] - - - Updated - - - That's no longer true since version 1.0. Scale height is no longer a constant.

It appears that none of the atmospheres follow the old isothermal/constant scale height model anymore. I've got the Kerbin atmosphere figured out pretty close if you ever need it. It's described in the following thread: http://forum.kerbalspaceprogram.com/threads/117069-Great-New-Physics-Thread%21?p=1940443&viewfull=1#post1940443

I've learned quite a bit about the Kerbin atmospheric model since my last post on this topic. I will now share with you what I've learned. First, just about everything you need to know about atmospheric models can be found here: Rocket & Space Technology, Atmospheric Models. If at any time I reference a table or formula, it can be found in that web page. The U.S. Standard Atmosphere (USSA) is summarized in Table 4. As has been noted, Kerbin's atmospheric model is based on the USSA, though with the vertical scale compressed to 80% normal height. However, it's not a simple as just taking the height values in Table 4 and multiplying them by 0.8. Altitudes in the USSA are in units of geopotential meters, while the altitudes measured in KSP are in units geometric meters. What Squad has done is to take the heights in Table 4, convert them to geometric heights using equation 15 (where ro= 6371 km), and then multiply the result by 0.8. For example, the first temperature transition point is, z = 6371*11/(6371-11) * 0.8 = 8.81522 km Once these conversions are completed, computing the base temperature is easy because the temperature-height profile is just a series of line segments. However, to this base temperature are added latitudinal and diurnal modifiers. The latitudinal modifier at sea level varies from +17 K at the equator, to 0 K at 30o latitude, to -50 K at the poles. The diurnal modifier varies according to latitude and solar incidence angle. At sea level at the equator, the diurnal modifier varies from +9 K at the halfway point between noon and sunset, to 0 K at the halfway point between midnight and sunrise. The diurnal variation is greater at mid-latitudes and less at the poles. The base temperature adjustment also varies as a function of altitude. It is greatest at sea level, decreases to zero at approximately 16 km, and then begins to increase above approximately 26 km. At sea level at the equator (approximately the location of KSC), the maximum and minimum air temperatures are, Tmax = 288.15 + 17 + 9 = 314.15 K Tmin = 288.15 + 17 + 0 = 305.15 K Atmospheric pressure is also based on the USSA. As with temperature, the vertical scale of the pressure-height profile is reduced to 80%. Although this makes sense in terms of gameplay, it creates an internal conflict. Many calculations related to Kerbin's atmosphere, such as air density and speed of sound, use a gas molecular weight of 28.9644 kg/kmol (same as Earth). However, since the pressure-height profile is reduced to 80%, this means that the pressure drop that would be expected to take place over 1000 meters in altitude must now take place over 800 meters. This means that Kerbin air must be heavier than Earth air, i.e. M = 28.9644/0.8 = 36.2055 kg/kmol. The rate of pressure decrease is internally inconsistent with the atmospheric properties used in other computations. Also be advised that atmospheric pressure is not effected by temperature. The same pressure-height profile is used globally regardless of local temperature. In KSP, atmospheric pressure is calculated using a floatCurve. As such, pressure doesn't follow a pure exponential function. Furthermore, the normal real-world equations used to compute pressure (equations 20 and 21) won't work correctly when the input is geometric height rather than geopotential height. To derive equations for pressure as a function of altitude, I found it easiest to simply plot LN(P) versus z and then fit the data points with a trendline. The equations provide quite good accuracy (particularly at lower altitudes); in almost all cases the error is just a fraction of a percent. Above 62.3 km the pressure curve turns abruptly as the pressure is forced to suddenly go to zero at 70 km. Below is a summary of all the equations. These equations are not always an exact recreation of numbers produced by KSP, but they are a very close approximation. Note that the temperature given is the "base temperature". It does not include any of the latitudinal or diurnal adjustments. [TABLE=class: grid, width: 1000, align: center] [TR] [TD=colspan: 3, align: center]Kerbin Standard Atmosphere, 0 to 70 km[/TD] [/TR] [TR] [TD=align: center]Geometric Altitude, z (km)[/TD] [TD=align: center]Kinetic Temperature, T (K)[/TD] [TD=align: center]Pressure, P (Pa)[/TD] [/TR] [TR] [TD=align: center]0-8.815[/TD] [TD=align: center]288.15 – 8.11117 × z[/TD] [TD=align: center]EXP[ –5.6684193E-05 × z3 – 1.9580663E-03 × z2 – 0.14836114 × z + 11.5260885 ][/TD] [/TR] [TR] [TD=align: center]8.815-16.050[/TD] [TD=align: center]216.65[/TD] [TD=align: center]EXP[ 3.6215104E-06 × z3 – 1.1135486E-04 × z2 – 0.19514262 × z + 11.753405 ][/TD] [/TR] [TR] [TD=align: center]16.050-25.729[/TD] [TD=align: center]196.7513 + 1.23980 × z[/TD] [TD=align: center]EXP[ 1.8765033E-06 × z3 + 4.0682342E-04 × z2 – 0.21018261 × z + 11.868445 ][/TD] [/TR] [TR] [TD=align: center]25.729-37.879[/TD] [TD=align: center]139.7102 + 3.45679 × z[/TD] [TD=align: center]EXP[ –4.1690244E-05 × z3 + 5.0761226E-03 × z2 – 0.36509550 × z + 13.508117 ][/TD] [/TR] [TR] [TD=align: center]37.879-41.129[/TD] [TD=align: center]270.65[/TD] [TD=align: center]EXP[ –3.6083972E-04 × z3 + 0.044146606 × z2 – 1.9496301 × z + 34.813685 ][/TD] [/TR] [TR] [TD=align: center]41.129-57.440[/TD] [TD=align: center]411.8568 – 3.43327 × z[/TD] [TD=align: center]EXP[ –8.6910710E-07 × z3 – 1.0609374E-03 × z2 – 0.062235305 × z + 8.6153226 ][/TD] [/TR] [TR] [TD=align: center]57.440-68.798[/TD] [TD=align: center]354.7555 – 2.43916 × z[/TD] [TD=align: center]See below[/TD] [/TR] [TR] [TD=align: center]68.798-70.000[/TD] [TD=align: center]186.946[/TD] [TD=align: center]See below[/TD] [/TR] [TR] [TD=align: center]57.440-62.300[/TD] [TD=align: center]See above[/TD] [TD=align: center]EXP[ 1.5412356E-05 × z3 – 3.5432535E-03 × z2 + 0.058616347 × z + 6.7777398 ][/TD] [/TR] [TR] [TD=align: center]62.300-70.000[/TD] [TD=align: center]See above[/TD] [TD=align: center]EXP[ –9.37298921E-04 × z5 + 0.304103311 × z4 – 39.4630615 × z3 + 2560.291576 × z2 – 83044.59921 × z + 1077314.96395 ][/TD] [/TR] [/TABLE] From the data in the table above, air density and speed of sound are calculated using the following: Density, à(kg/m3) = P/(RT) Speed of sound, C (m/s) = (γRT)1/2 where, Specific gas constant, R = 287.058 J/kg-K Specific heat ratio, γ = 1.400

Kerbin's atmosphere is based on an 80% US Standard Atmosphere model, but it doesn't match it exactly. It uses a series of points taken from the standard model but, to estimate values in between, those points are connected with splines. Therefore, there will be some deviation between what KSP computes and what your equations will yield. Should be pretty close, though. (EDIT) Something else that will throw off the results is that the standard model uses geopotential height (h), while KSP altitudes are geometric height (z). A conversion must be made before using your equations.

Yes it does. I think I understand now. Sorry to have bothered you with so many questions, but I really like knowing how things are computed. I appreciate your time and patience in explaining.

I always make my orbits coplanar before performing a rendezvous. Makes it much easier.

^This^ usually works pretty well for me. There is also this: Orbital Rendezvous Made Easy