![]() It’s totally possible to build a rocket with this much Δv that won’t even make it up into orbit because the majority is in your transfer stage, making it too heavy to get up to orbit after your lifter burns out low in the atmosphere. Think again!! The reason we made sure to break down our Δv amounts in stages is because you will be using different amounts of your total Δv at different stages in your mission. Important: It’s easy to get to this stage in the build process and see you have much more Δv than you need and assume everything is good. Here is the complete breakdown of our rocket:ġ9.811t 6,327m/s (5,285m/s minus payload Δv) Any inefficiency in the ascent can be made up for with the surplus Δv available in our transfer stage. Even if we take into account the atmospheric Δv for our lifter stage, we still have 3,450m/s of Δv combined, which is enough to satisfy our 3.4km/s Δv requirement to get to 70km orbit. Note that we are using atmospheric Δv here for our boosters, as they will be firing only within the densest parts of the atmosphere. So, slapping together a decoupler, tank and suitable atmospheric lifter engine we end up with: As mentioned before, this will take 3.4km/s of Δv, but we don’t need all of this for the lift stage, as the transfer stage contains enough Δv to take up some of the work of getting into orbit, and we’ll also be building a booster stage. Next up, we need the part of the rocket that will get us from the atmosphere into space. Save this and each following craft separately. Once we subtract the weight of the NRAP from the total weight, we will also have the specific weight of our transfer stage. Now, KER gives us the Δv of our transfer stage, which is more than enough at 1,602m/s. Larger rockets with larger fairings you will want to take into account. The weight of the fairings is too small in this case to bother factoring into our calculations. ![]() We’ve also attached a Procedural Fairing base, but note that we haven’t created any fairings. You can see that we set the weight to match that of our payload. Throwing together all the parts needed to match the requirements we made during planning gives us this:Ītop our transfer stage, the first part that we created for this craft was an NRAP test weight. The top of the rocket will contain our payload, the communications satellite we defined during our mission planning. When building rockets, always build from the top down. Our requirements are set – let’s start building! Construct your payload So, in total we need at least 4,570m/s Δv to get to Mun. For Mun, all our missions require at least +300m/s Δv, which is enough for a direct return. The further you travel, the more extra Δv you want to try to bring along. We don’t actually need all that Δv because we won’t be placing the ComSat into such a low orbit, but we’re going to use the full value anyways so we have some extra fudge room for unforeseen mission problems. We will use the amount given here on the chart so once to LKO it’s 860m/s Δv to transfer us to Mun and then once we get there we need 310m/s Δv to enter into orbit. Click the image above and late in the thread you will find discussion on the Δv value for ascent to LKO. The first thing to note is that the Δv required to get to LKO (defined here as 80km) can vary by a few hundred meters per second depending on your ascent profile and the engines you are using. Here is the piece of the map we need to get to Mun, click on the image for the full map. To do this, we’ll make use of a Delta-V map that will give us the numbers required to get to various places in the Kerbol system. Now that we know what we’re sending to Mun, let’s figure out what we need to get it there. We should also want a means to move the satellite after its been deployed and of course a probe core is required to control it. We will need communications equipment, batteries to run them on, and solar panels to charge the batteries. Since we won’t be bringing along any kerbals, life support isn’t an issue. ![]() In this case, we want to go to Mun and deploy a communications satellite. The first step is to decide what you want to accomplish in your mission. Our goal will be to place a communications satellite into equatorial orbit around Mun. This includes multi-part missions to Mun, so we will be using a Mun trip as the example for this tutorial. While we’ve had some rockets fail due to design issues with the rocket itself during the ascent to orbit, none of our craft have failed to achieve their objectives once they have made it into space. This quick guide will help you plan and build rockets for missions you are looking to undertake, and follows the technique utilized by the KSA to plan all their missions. ![]()
0 Comments
Leave a Reply. |