Kraken1950

Hello, Something is bugging me about contracts. Companies offer you an advance when you accept a contract. The amount, just like the completion, depends of the difficulty of the mission. How should this advance be considered ? Is that a way for the game to tell you if a rocket design is acceptable ? For example, a contract gives me 100 000 credits as an advance. Should I consider my design as : - Good : if total cost < advance - Bad : if total cost > advance - Or advance is not related, you might need to put more money on the table to achieve the objective ? I have a mission which requires to bring a class C asteroid in Kerbin orbit and the advance is 163 000 credits, (+ 429k credits for completion) do you think it is enough ?

Amazing job ! Great inspiration for my future mining base. What do you use and how do you land the Fuel Rover ?

From my experience, to deorbit and land you need between 580 and 750 Dv, getting back to orbit will cost you around 680 Dv. So the total cost of the maneuver si between 1260 Dv and 1430 Dv. You can build almost anything as long as it has at least this much Dv. For example, something that ugly does the job (TWR is > 4 ; Mass : < 8t)

Well, I had the same problem until now, thanks to this topic. For me, it turn ou to be an inclination problem, it seems that for synchronous orbit the "reasonable deviation" was very, very, very tight. When I remember some of other orbit missions I did, they were not as demanding as they were for a sync' orbit.

I would say KSP has a long and steep learning curve ==> learning wall is a good term to define it. But behind the wall, there is another and taller wall... However, when you succeed in something, it is amazingly rewarding ! Hopefully there is a strong, willing to help community. I think it's a bit frustrating too, as sometimes you think you are managing some mechanics but then realize that you have still a lot to learn and understand.

Thanks you all for your answers !

My primary goal is to understand what i'm doing and being able to anticipate my future space travel. When I’ll be familiar with the theory and calculation, I will sure save time & use a third party mod. But for now, it is math !! Thanks to you, I see what I did wrong so I will recalculate the Delta V. Can you confirm I am correct for the 2nd stage ? This stage is used only in space. [Quote] My question is more along the lines of: why do you feel that you are unable to design ships for interplanetary travel? Perhaps you have not realized it yet, but the KSP solar system is tiny, the the dV costs are tiny as well.[/Quote] Indeed, I saw that for most planets or satellites you need between 6k to 8k Delta V but I feel I ‘m unable to design rockets because I don’t know what I’m doing : I don’t know how much I need and I don’t know how much delta V I’m building by putting all those fuel tanks & engines together. Of course, I can use mods and existing resources but where is the creativity and the wonderful process of learning ? Thank you for your advice on the rocket design. However, when I check the values of the LV-T45, ISP is slighty inferior (270 compare to the 280 of the LV-T30) in atm but slightly better in space (320 > 300) and I get less thrust for a 0.25 t gain in mass (+ the mass of the extra tank fuel that you recommend). How it will help apart from burning longer ? I was using the LV-T30 ‘cause of alternator now that I have solar panel, I can reconsider it. Yasmy [Quote] I'll address your second question on how to calculate the cost of interplanetary travel. First, there are some high quality delta-v maps around. Be careful to use an up to date map. While I've calculated everything myself from time to time, I still use delta-v maps when planning most of my missions. Second: It appears you correctly calculated the first burn of a Hohmann transfer from low Kerbin orbit to the Mun, which is about 860 m/s. Next you might want to calculate the second burn to circularize in Munar orbit, but the second Hohmann burn equation is not correct because it ignores the presence of the Mun[/Quote] Thanks for your answer, lots of thing to process though ! What do you mean by “mu” Kerbol, what value is it ? Mass x Gravitational constant ? Secondly, in the Hohmann transfer orbit formula why don’t we use R (radius of parent body) in this formula ? Once out os Kerbin SOI the R could be Kerbol ? I will check on the vis-viva formula as do not understand the use right now. Thank you all for your answers, it is a great help !

Hello, I have enjoy the game in Sandbox mode and now i'm starting a career of my own. If I am able to design rockets that can go to Mun & Minmus, land and come back safely, I am currently unable to produce rockets to go visit other planets without copying others' design. I'm fed up with this situation so I decided to do some math and get familiar with the Delta V and transfer manoeuver formulas. I hope I'll finally be able to design adequate spaceship without simply copying ! The problem is MechJeb is out with 1.05, therefore I can't check if my calculations are good. I'm posting this to ask for help and check if my method & results are good so I can do more math to travel on the edge of Kerbol system ! Here is a rocket I have designed, it can go to Mun or Minmus, orbit then come back home : [IMG]http://image.noelshack.com/fichiers/2015/47/1448233138-orbit-2.jpg[/IMG] Total mass is 43.2 t as shown on the picture. To calculate the Delta V I separated the rocket in 2 stages : - 1st stage : 4xBACC + 1xFL-T800 + 1xLV-T30 + 4xTT-38K Radial Decoupler + 1x TR-18A Stack Decoupler for a total of 36.5 t ; fuel mass : 28.6 t ; dry mass : 7.6 t - 2nd stage : 1xFL-T800 + 1xLV-909 + the rest for a total of 6.7 t Given the example in the Wiki, I assumed that each stage must be calculate separatly i.e. first stage mass is 36.5 t and not the whole rocket for 43.2 t despite the first stage carry it all. Am I correct on this point ? 1. So 1st stage, using formula available in the wiki : g = 9.81 ; ISPaverage = 186.7012 (using the ATM value of engines 'cause atmosphere burn mainly) ; ln(36.5/7.6) my Delta V is 2873.985 m/s. If I consider that the total mass should prevail, I'm down at 1986.888 m/s of Delta V. 2. 2nd stage : Total mass = 6.7 t ; dry mass = 2.7 t ; ISP = 345 (vaccum value), my Delta V is 3075.977 m/s TOTAL DELTA V FOR ORBIT 2 : 5949.962 m/s (or 5062.865 m/s if 1st stage is calculated with 43.2 t) Am I correct ? I am using Excel sheet for calculation as I don't have a calculator. For manoeuvre transfer from Kerbin to Mun, I'm using those values (again the formula come from the Wiki) : r1 = 90 km r2 = 120 000 km R = 600 km µ = 3530.461 km I assume that I'm on a orbit around Kerbin at 90 km and I want to go to the Mun which is located at 120 000 km. Using the formula I obtain : Dv1 = 0,852798 km/s ; I want m/s so I multiple by 1000 = 852,798 m/s which is consistent with the information available on the Wiki If I want to know the Delta V for Duna, I just replace r2 by the Duna's altitude ==> 20 542 065 km. [IMG]http://image.noelshack.com/fichiers/2015/48/1448235263-duna.jpg[/IMG] Am I correct ? Thank you in advance for your answers !