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  1. Not sure if im even asking the right question. Lets say for instsance, I build a massive ship designed to travel the solar system. And on this ship I have multiple engine groups that i can toggle via the actions menu. Some are for efficency and others are for high thrust and others even are for finetuning maneuvers. The problem is, no matter which engine groups are active the delta v available and the current twr readout over in the staging section remains the same which makes performing maneuvers kind of a guessing game at burn times, whether i have enough fuel, and when to start each burn. Am i missing something?
  2. Annoyed by having to do a bunch of unit conversions? Use the TWR calculator, which automatically converts the units for you. Write your weight and thrust in the units KSP uses and have it be calculated! Program coded in Python. https://onlinegdb.com/b8Vou_r5X Just press the green RUN button at the top!
  3. Maneuver Node Splitter v1.7.0 Maneuver Node Splitter provides a GUI interface to split a single interplanetary transfer ejection burn maneuver node into multiple maneuver nodes. Version 1.3.0 comparison of the Unity skin and KSP skin above. Also shows the new 1.3.0 "repeat" option. Version 1.2.0 picture of the four modes for splitting nodes below. Why does it exist? If your vessel has a low TWR then it may not be possible to perform your ejection burn in a single orbit. By splitting your ejection maneuver into multiple burns you can raise your apoapsis a bit with each orbit until your final burn gives you an escape trajectory. How do I use it? 1. Get into orbit. 2. Create a maneuver node. 3. (Optional) Use Precise Node to move your maneuver node forward to the transfer window. 4. Set up the maneuver node to give you your ejection and encounter with your destination. 5. Open the Maneuver Node Splitter GUI by clicking the icon on the toolbar. 6. Use the left and right buttons to select how you want to split the maneuver node. 7. Enter the appropriate values into the text boxes. For example: delta-V values for the amount of delta-V you want to burn in each maneuver. 8. Click "Apply." Your original maneuver node will be replaced by multiple maneuver nodes. Each of the first maneuver nodes will be created based on the values you entered, and the final maneuver node will have the remaining delta-V. Your final ejection burn maneuver node will be around the same time as the original maneuver node (depending on what values you entered). Example: After creating an ejection burn requiring 2500m/s I open the GUI and enter 250 and 300 then click "Apply." The mod will split my original maneuver node into three maneuvers: the first will be 250m/s, the second will be 300m/s, and the third will be 1950m/s (the remainder). Note: Once your maneuver nodes are created it's up to you to actually perform the burns. This is the hard part. If you do not perform the burns precisely enough then the subsequent burns will be impacted. Luckily, as long as you're close it's usually easy to do minor adjustments to the later maneuver nodes using Precise Node to restore your rendezvous. Usually what you will need to adjust will be the *timing* of the subsequent maneuver nodes (since burning a slightly different amount from what the maneuver node specified will give you a different orbital period) rather than the delta-V. Additional Tips and Notes: It works with both mid-course plane-changes and direct ejection burns. The additional maneuver nodes will be created prior to the timing of your original maneuver (if your maneuver node is far enough in the future) so that your ejection time is left as unchanged as possible. The GUI will modify your upcoming maneuver, so don't add extra maneuvers before your ejection burn. The GUI will preserve any maneuver nodes that come after your ejection burn as long as they're far enough later than the original maneuver. After clicking "Apply" there will be an "Undo" button that will restore your prior maneuvers, so it's easy to just throw some numbers in and see how they work out. If it's not to your liking you can easily undo it. The "+" button will add more text boxes (for splitting the original maneuver into more burns) and the text boxes will have "x" buttons next to them for removing them (when you have more than one text box). Stock KSP has a bug where projected orbits sometimes do not show when multiple maneuver nodes from separate orbits are placed directly on top of each other. This is not a bug with the Maneuver Node Splitter. It's usually best not to raise your apoapsis above around 7000km prior to your ejection burn because of the possibility of an encounter with the Mun. While the tool can convert your ejection burn into a dozen or more tiny burns, it's usually easier to perform the ejection in fewer burns rather than more (due to the impact on later burns of not performing the earlier burns perfectly). Your current orbit very slowly drifts when your vessel is not on rails (timewarp) due to floating point math. This can impact your ejection maneuver while you are trying to set it up, so it's best to set it up at timewarp, if possible. Pics: Download GitHub Source GitHub Version History v1.7.0 (2017-03-18) -Compiled for KSP 1.2.2 -Fix for splitting maneuvers that include a normal component. v1.6.0 (2016-10-13) -Update for KSP 1.2 -Includes a version file for KSP-AVC (thanks Henry Bauer!) v1.5.0 (2016-03-30) -Updated for the KSP 1.1 pre-release. Only use this version with KSP 1.1, not KSP 1.0.5. v1.4.0 (2016-03-20) -Added error messages when the input values cause early ejection from the original SOI or an encounter with another SOI. v1.3.0 -Added a "repeat" option to make specifying how to split the nodes easier. v1.2.0 -Maneuver splitting can now be specified by deltaV, orbital period, burn time, or apoapsis (splitting by burn time requires that you install KER). Thanks @Val for the suggestions! v1.1.0 -Added support for using either the KSP skin or the Unity skin (the new default), configured via settings.cfg. v1.0.0 -Initial release. License Maneuver Node Splitter is licensed under the MIT license.
  4. So umm, a couple months ago I was lazy and used mods like Kerbal Engineer for data readings. Soon I became interested in collecting those data values myself. Soooo I headed to the cheat sheat in the KSP wiki. I learn’t ‘The Rocket Equation’ quite easily and then moved onto TWR. But whenever I plugged in the numbers it would turn out wrong. So I spent hourrs trying to solve this problem with no results. Here is the formula off the wiki: Where Ft is thrust m is mass g is the gravitational acceleration I’m also using a scientific calculator for these calculations. Any help would be appreciated whatsoever!!!
  5. HELP I am building a stock replica of the USS ENTERPRISE, I don't know how to show a picture of it. My problem is that my engines are not powerful enough/ don't burn long enough. I want it to have fair twr (from 1.00 to 0.50) and a long burn time (from 1h to 30m) I can't get this but I see giant stock sstos online and on youtube... I only need it to burn for 1 hour and I can refuel at my station. But it keeps running out of fuel. For instance I went to Duna once and I had enough fuel to go from low-kerbin-orbit (LKO) to intercept of duna but no closer. I tried many engine configurations and many different fuel and thrust values but I always go the same distance The fuel makes the engines last longer but makes the thrust less due to its weight. I need a solution to this problem and I can even give the craft file if you want. No memes or unrelated content plz, and no useless content either... Thanks in advance - A FAT KERBAL
  6. Hello everyone! Recently I've been messing around with HalfRSS mod (best decision ever!) and, of course, tried to recreate Flacon 9, both 1st and 2nd stage.I've found this sheethttps://docs.google.com/spreadsheets/d/1X9FUdHnowboCrjoWKpTM5OtLEqj26UWhF0UbEnON5_Q/edit?f=true&noheader=true&gid=18#gid=27 With pretty reasonable info about falcons parameters. I've scaled them down to be suitable, for HRSS, taking total delta-V as my base. Parameter | Falcon 9 | HRSS | Mine Total dV | 9380 | ~7200 | 7038 1st st dV | 3076 | ~2371 | 2369 2nd st dV | 6388 | ~4925 | 4669 With all this, i struggle to reach orbit. it seems that my 2nd stage has not nearly enough TWR to push craft to orbit. separation occurs somewhere between 40 - 50 km high (AP at 95-100km), and 2nd sdtage starts its burn right away. sadly no matter what pitch I set, 2nd stage doesn't even burn through half of its dV, until it falls back to atmosphere. What might be the reason for this? Is Falcon9 data I based inaccurate? or its HRRS fault (longer to reach AP in RSS than in HRSS?), or maybe my gravity turn is made badly? Cheers
  7. There's been a lot written on this board about optimal TWR for rockets. Math got involved, some of which went over my head, but the consensus seemed to be that 2 was a good number. What I'd like to know is if the same Math can be used to prove the "best" TWR for a spaceplane in closed cycle mode. Now before everyone heads for the hills, try not get too freaked out by the fact it has wings. Wings generate lift, in exchange for creating a bit of extra drag and extra mass. If you angle the wings up at 5 degrees relative to the fuselage, tweak the tailplane/canard so the plane holds a nose angle between half a degree and one degree nose up when SAS is set to prograde, your lift/drag ratio is going to be more or less constant throughout the closed cycle part of your flight. Another way to look at it, is that since we have wings, and wings are counteracting gravity, we only have to be concerned with drag. So, whilst in a rocket, we are concerned about our margin of Thrust over Gravity, in the airplane, we are concerned about the margin of Thrust to Drag. The greater the margin in favour of Thrust, the lower our losses, but adding extra engines to increase TWR adds dry mass, and means we have less delta V to start with. Of course, this comparison is only valid if the airplane is generating enough lift to support itself while building velocity. You could set the wings at a lower angle, or zoom climb to a high altitude on jet power before going closed cycle, and temporarily get lower drag, but it won't be sustainable as you'll soon fall back into thicker atmosphere and be worse off. That is why it is best to chase optimal "lift:drag" ratio rather than absolute lowest possible drag. Let's say it weighs 30 tons. In Kerbin gravity, that works out to a gravity force of 300kn if you round things up a bit. Do we need 300kn lift ? Well, not quite. Let's say we're going at 1400 m/s - that's actually two thirds of orbital velocity, meaning that orbital freefall is already going to be cancelling most of gravity. We only need to get enough lift to make up the difference, and stop the airplane descending. As our velocity continues to increase, our apparent weight decreases. Since we're holding a constant AoA at constant lift/drag, our lift now exceeds weight, and we drift upwards, until the thinner air causes lift to no longer exceed weight. At this new higher altitude however, drag is less, and so on. As you can see, this means it gets easier and easier to accelerate as time goes on, and fuel burnoff is not the only factor at play. At this point , some of you will be saying "so what" because, with RAPIERs in closed cycle mode, your TWR on this phase of flight is going to be so high as to make such optimisations pretty irrelevant. However, this past week or so, I've been building craft for rescaled Kerbin. I'm currently using a rescale factor of 3.2 which raises orbital velocity from 2200 m/s (mach 7) to 4200 m/s (mach 14). This makes things more than twice as difficult for a spaceplane. Stock, you can get 1600 m/s air breathing, and so theoretically only need 600 m/s delta V in closed cycle mode to make orbit. With the rescaled system, even if you manage 1600 m/s air breathing, you need another 2600 delta V to make orbit - more than four times as much. I don't think there's any chance of packing enough fuel in to do that with a 305m/s specific impulse RAPIER - 800 m/s NERVs are probably your only option. However, they have much worse TWR - 3 tons for 60kn, instead of 180kn for 2 tons. Pure chemical rocket engines are better still - the Dart manages RAPIER thrust levels for just one ton, and is far from the highest TWR engine available. Compounding the issue, at the start of your closed cycle burn, you are nowhere near orbital velocity on rescaled Kerbin, thus are still feeling the full effects of gravity. This holds you deeper in the atmosphere, with greater drag losses, for longer. Thus, this "optimal" spaceplane TWR becomes such a vexed question. Starion 2 - A working prototype I can SSTO with the rescaled Kerbin but such a craft ends up with little fuel left over in a very low orbit. So the Starion 2 was a mod of the original SSTO that dumps its jet engines at flameout to get extra delta V. Two whiplashes, three nervs. Takeoff weight 47 Tons. Upper stage mass (after Whiplash stage separation) 38 tons Mass breakdown of the upper stage Stage 2 Mass 38.6t Liquid fuel 19 t Nerv engines 9t Payload 6.1t (cockpit, crew cabins, docking gear, docking fuel) Aerodynamic bits 4.5t (wings, control surfaces, intakes and cones) Flight Logs I took some screenies on the way up. Due to the AeroData GUI being open, they give some insight into how drag losses changed as the flight progressed : Time Velocity Weight Alt L/D Drag (sec) (m/s) (kN) (M) (ratio) (kN) 752 1491 345 32340 3.7 73 827 1674 328 33435 3.7 80 972 2186 296 38824 3.6 64 1102 2723 264 47842 3.6 28 1174 3114 248 50712 3.5 26 1304 3904 218 61815 3.4 12 Imgur album of the ascent shots from which this data was transcribed - https://imgur.com/a/xNSfY
  8. Can someone please explain to me my plane's TWR chart as provided? I used KER to find the TWR in every Mach Number. Here it is:
  9. Decided to make an experiment and compile the data for something this basic, yet very important. So, here is it! Craft: stock "Jumping Flea" (Flea booster with MK1), straight launch, variable TWR (adjusted in VAB from data given by KER): TWR 1.2, highest real altitude: 4100 m flameout: 3100m TWR 1.5, highest real altitude: 6200 m flameout: 4300m TWR 1.7, highest real altitude: 7200 m flameout: 4600m TWR 2.0, highest real altitude: 8000 m flameout: 4700m TWR 2.3, highest real altitude: 8250 m flameout: 4700m TWR 2.5, highest real altitude: 8320 m flameout: 4600m TWR 2.7, highest real altitude: 8350 m flameout: 4500m TWR 3.0, highest real altitude: 8350 m flameout: 4200m TWR 3.3, highest real altitude: 8350 m flameout: 4000m TWR 7.6 (maximum), highest real altitude: 8100 m flameout: 2100m Explaination: this means that: at TWR lower than 2, your craft will be burning fuel fighting the gravity, and at TWR higher than 2.5, your craft will be burning fuel fighting atmospheric drag. Enjoy! ## Update 2016/09/30 Quick check with Swivel+FL-T400+2xz1k batts+RC001s+Adv.NoseconeA (2,156 DeltaV) confirms the data: TWR: 1.7, highest real altitude: 87,600 m flameout: 31,000m TWR: 2.2, highest real altitude: 117,500 m flameout: 31,000m TWR 2.2: ## Update 2016/09/30 - 2 In response to criticism, I decided to make a small "usable" 7 tone "payload" (Payload A). The payload has everything to make orbit, keep in orbit and descend down. To repeat, this thread about ideal TWR for first stage / launching stage ### Payload A, first test Payload A config: Protective Nose Cone Mk7 + LCR01 RGU + Srvc.Bay 2.5m(3x Z1k batt, 2x SP-L solar panels, 2x MK2-R radial chutes) + Advanced Reaction Wheels, Large + X200-8 Fuel + LV-909 "Terrier"+Rockomax Decoupler. --- Payload A weight: 7,000 kg This payload will be launched using only one stage - using two ascend methods, using two different TWRs. The methods: 1) direct climb for statistics: SAS on, max throttle, ignition. No Stage 2 disconnect. 2) manual gravity turn: - 0 degree until 2,5km; - course to 15 degree(75 on navball) at 2,5km; - course to 35 degree (55 on navball) on pass 15km; - course to 55 degree (35 on navball) at 25km; - course to 75 degree (15 on navball) at 35 km; (this step was skipped on 2.2 TWR due to atmospheric heat **) - deactivate if apoapsis reaches 80km, wait until T-45s (accordingly, this step was much longer on 2.2 TWR) - burn at horizon line under prograde till end of stage: output stage 1 data - disconnect stage 1 and finalize burn using stage 2: output payload A in orbit fuel left will be also noted: out of fuel/flameout for 1st stage (altitude at; horizontal and vertical speeds), amount of fuel left on payload after circularization at 80/80km. #### Payload A (stage 2) - uplifter A (stage 1) uplifter A config: (Payload A +) Jumbo 64 tank + RE-M3 Mainsail (+3x launch stability enhancer, start only) 3,218 projected stage 1 DeltaV; 6,370 projected total DeltaV ) [ craft file link ] Results: ##### Direct climb data TWR 1.25, highest real altitude: 268,000 m flameout: 72,000m TWR 2.20, highest real altitude: 615,000 m flameout: 69,000m ##### Manual gravity turn data info: TWR 2.20 appears to compress air higher (hidden aerodynamic center) - thus rocket becomes less stable and either smoother transition between nodes (used here) or additional lifting surfaces required. TWR 1.25: apoapsis at flameout: 82,000m periapsis at flameout: -390,000m Stage 2 80km/80km orbit fuel left: fuel - 247/360; LOX - 302/440 TWR 2.20: apoapsis at flameout: 86,000m periapsis at flameout: -22,000m Stage 2 80km/80km (90/90km actually) orbit fuel left: fuel - 340/360; LOX - 416/440 ** apparently there is a room for improvement! "Engine idling on suborbit ascend equals wasted fuel". This case is free to be tested! Probable method: throttle down after leaving atmosphere (~28km). Reason: it looks like with TWR 2.2 atmosphere heat prevents efficient acceleration, requiring higher angle of attack. But according to Oberth effect, lower attitude accelerations are more efficient, thus its better to take it slower below.
  10. Based on an idea born in another thread, I decided to do some experiments in RSS (which I'm currently using as my career, with SMURFF - no RO) to look at TWR, drag losses, gravity losses, and ascent profiles. I created a basic rocket with four Kickbacks, then simply thrust limited the Kickbacks to 50%, 75%, and finally 100%. After an initial tip to the east, SmartASS would hold the craft on a surface prograde vector. Once the navball switches to an orbital reference, SmartASS changes to hold orbital prograde until the Ap is 250 km. MechJeb is then told to circularize at AP. After conducting 18 test runs, I've created an album with the best run at each thrust level, posted below. It was amazing that a single degree change in the initial tip can make a big difference - in one case, reducing gravity losses by over 100 m/s. It was also eye-opening to see just how small the drag losses are compared to the gravity losses. Conclusions based on all this: 1. Launch with an initial TWR between 1.5 and 1.9. 2. Don't worry about drag - gravity losses are much larger and more important. 3. Ignore the flame effects. 4. At higher thrust levels, crank it to the east immediately after launching, and be precise about it. 5. Try to keep vertical velocity below 800 m/s. If it's over 1 km/s, you're going to have noticeably higher gravity losses. 6. Getting a rocket to orbit in RSS for less than 9 km/s of delta V is very doable. Using less than 8.6 km/s is a harder but still achievable goal. UPDATE: After making all these ascents in RSS, I redid the tests in stock with a slightly different rocket (but same concept) to see what was the same, and what was different, You can find the stock version here. UPDATE 2: After editing this OP, the embedded imgur album disappeared. You can find the album here.
  11. Hi , I'm trying to understand something in the game for a while now , some of the plane I made and design in the game have less TWR than others and I have the surprise while flying them to see more m/s on them like what ! For eg I have multiple 1.79 TWR aircraft that can reach MACH 1 ( DELTA wings) without using wet mod engine and some aircrafts with 4 or even 5 TWR and they can't even get 350 m/s in full dry throttle so I'm stoke ! I'm looking the aerodynamic closely but I can't still explain...do you guys have these kind of problems ?
  12. Got a question for you all. I design my stages to not exceed 22 m/s*s of acceleration below 40 km. Even above 40 km it is usually not needed unless I aim for a high kerbin orbit. I noticed that with higher acceleration I get reentry effects during ascend. Anyone have a different opinion.
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