18Watt

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About 18Watt

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  1. I’ll have to try that, sounds like a great idea! Do you still bind torque to anything, or just leave it full blast? Thanks for that suggestion!
  2. The most common cause is your center of mass has shifted rear-wards as you burned fuel. The craft was stable with full fuel, but as you burned fuel the center of mass moved aft. There are several ways to deal with this. One is to design a ship (plane) in which the center of mass doesn’t move. In other words, the center of mass stays in the same location wether the ship has full fuel, or is completely empty. Keeping most of the fuel in the ‘middle’ of the ship, or centered around the center of mass is helpful. Another way to overcome that issue is to move fuel once you are in orbit. Before entering the atmosphere, move some fuel from the rear tanks to the front tanks. How much? Good question. If you enter the atmosphere, and still lose control, you didn’t move enough fuel forward. On the other hand, if you move too much fuel forward, the ship can become too nose-heavy to control with the elevator. Start by looking at your center of mass and center of lift in the SPH. Then take most of the fuel out of the craft, and look again.
  3. If you download the .zip package for Mac OSX and it loads/hangs to a black or blank screen, try this: Open Finder to the folder where your working copy of KSP is stored. Locate the 'KSP' file. Probably has an icon that looks like a Kerbal. This is the file you double-click to open KSP. Don't open it yet. Drag the 'KSP' file out of the KSP folder, drop it on your desktop. Next, drag the same file from your desktop BACK to the KSP folder, where it originally was. Now try running KSP by double-clicking on the KSP file. I've needed to do that since at least 1.4.
  4. This post is to share some tips at improving the efficiency of turboshaft engines, driving propeller blades (airplanes) or rotor blades (helicopters). The concepts should apply equally to electric rotors driving propellers or heli-blades. I'm using 1.7.3, the electric rotors, turboshaft engines, and propeller/heli blades are new to stock KSP, so in later versions some of this info might become outdated. It's easy to focus on either the Turboshaft Engine, or the Prop/Heli blades when troubleshooting 'why doesn't my vessel work'. The reality is you need to look at both elements to make a functioning prop-airplane or helicopter. The engine produces torque, which spins a shaft. This is important, torque produces zero thrust. Add all the torque you want, it will not produce any thrust- until it is coupled to a lifting device, such as a propeller blade or heli blade. On the other hand, the prop/heli blade also produces no thrust unless it is moving. You can angle the blades any way you want, they will produce no thrust unless they are moving. The movement is provided by the Turboshaft Engine (or electric rotor). As of 1.7.3, the stock engines can rotate at a maximum rate of 460 rpm, which is evidently a Unity limitation. Adding torque will increase rotational speed (rpm) up to that limit of 460 rpm. What happens if you are already at 460 rpm, and increase torque? That's an important question. What happens (in 1.7.3) is you increase the Fuel Flow (or EC draw), but do not get any increase in rpm. Beyond 460 rpm, adding torque is simply wasting fuel. In the following examples, we're going to experiment with turboshaft engines. There are two variables we are going to adjust, and unfortunately they are on two different parts. One is the Torque of the Turboshaft Engine, the other is the Authority Limiter of the prop/heli blades. To make things easy, I like to assign these values to action groups. I assign Engine Torque to the Main Throttle, and the Blade Authority Limiter I assign to Translate Forward/Back (usually 'H' and 'N'). Okay, lets get started. Here's a turboshaft engine we're going to play with. It's in the 'propeller' configuration, but the idea is the same for helicopters. Ok, we have an engine built on a stand, let's play with it to see how Torque, Blade Authority, RPM, Fuel Flow, and Thrust are related. In the next spoiler window, I'll play with Torque and Blade Authority Limit, to see what happens to rpm and Fuel Flow. Keep in mind that Thrust is only dependent on rpm and blade angle. If my rpm and blade angle stay constant, but my Fuel Flow increases, I have not increased my thrust. I'm just wasting fuel at that point. So, one goal is to find the minimum Fuel Flow which will maintain a specific rpm at a specific blade angle. Here goes. In the next spoiler window, I'll demonstrate an actual aircraft, making adjustments to torque (and Prop Authority) to reduce fuel burn. Ideally I'd use a single-engine airplane to keep things simple. However, counter-acting the torque effects of a single-engine are difficult to design for, and fly efficiently. It's easier to just make a plane with two counter-rotating engines and propellers. Then, it flies quite easily just like a jet, with no nasty torque effects. The takeaway here is that to get the most out of the turboshaft engines and propeller or helicopter blades, you need to look at more than just the engine or just the blades. Both elements need to be adjusted for optimum performance. Ideally, you need to be able to adjust both Torque and Blade Authority Limit in flight, to adjust for varying conditions. Regarding efficiency, the big takeaway is that adding Torque beyond what is required to maintain rpm is just wasting fuel, and lots of it. As of 1.7.3, I believe the concept is the same for electric rotors driving propellers or heli blades- adding torque beyond what is required is only wasting EC.
  5. You’re missing an important part of the equation, the blade deploy limit. In addition to having the engine’s parameters displayed, also have one of the blade’s parameters displayed as well. Ive been tying the engine torque to the main throttle. I then tie the blade authority limiter to the translate forward/back keys (usually H and N I think). Start with the blades authority at zero. Then add some torque, on that helicopter 35% should be enough for the engines to reach max rpm of 460. Once your engine is spinning at target speed (460 is default), then slowly increase your blade authority. Once you get airborne, if you notice your rotor speed slowing down, add torque as needed to maintain rotor speed. In a nutshell, the engine speed and torque does NOT produce lift, only rotational speed. To produce lift, you also need to adjust blade angle.
  6. Here's what happens if you rotate too far during takeoff. I'm not saying it flies great this way (it doesn't), but it does indeed fly. Landing is going to be painful, because the main landing gear is gone too. Anyway, it flies, and actually looks like it's going to get a little more speed after getting rid of the back of the plane.
  7. Here's some shots of a MK3 version I built. This was built earlier than the one shown in the original post. I didn't like the look of this fuselage, although it worked fine. I also had to do the canard trick to balance out CG/CL issues, and then hid them inside the nose. With the trick of hiding the canards inside the nose, if you look close you can still see a little evidence of the canards poking outside the fuselage. I do this on purpose, because if I hide them all the way, I tend to forget they are there, which causes problems when I'm troubleshooting. You can hide them all the way inside the fuselage, and they still work just fine. Both of these are tricky to land. They are not very maneuverable. Also, I originally used the really small Jet engines, the Juno, because they looked a little more appropriate. However, the thrust from the Junos was not enough to make any difference, so I went with the next size up. A couple of advantages to using the MK3 form, or I guess disadvantages to using the round form- First, the MK3 cockpit hold 4 Kerbals, and more important has a useable cockpit view. The round cockpit (MK1-3) only holds 3 Kerbals, and the view from that cockpit isn't really useable for flying. Second, the MK3 cargo bay looks a little more realistic as a bomb bay. The round fuselage really doesn't have anything as cool. I used the SM-25 Service Module on the round plane in the original post, but it doesn't look the same. Also, sometimes when I blow the Service Module's panels to open it up, my wings blow off too, so that's a potential problem. Never had much interest in dropping things just to make explosions anyway. Then again, with the new seismic experiments, there's a legitimate reason for dropping stuff and making explosions.
  8. I wanted to build something similar to the Convair B-36 bomber, using stock KSP with the Breaking Ground Expansion. I also use the Making History Expansion. The B-36 was a heavy bomber, conceived when jet engines were borderline science-fiction. The original version had 6 piston engines driving 6 propellers. Later, when they decided jet engines might work for airplanes, they just tacked four jet engines onto the B-36, on twin-engine pylons towards the wingtips. So the B-36 ended up having 6 radial piston engines with propellers, and 4 jet engines, hence the phrase "Six Turning and Four Burning!" It's a goofy concept, but apparently it actually worked fairly well. Here's my attempt at making something similar in stock KSP. The actual B-36 used it's jet engines for takeoff (after they added them..), but my example is capable of taking off using the propeller engines only. Each engine has 8 of the "B" size propellers. At 1,000M each engine only needs about 15% Torque to maintain max rpm (460). Turning the torque down to 15% gives me a total Fuel Flow of about (0.25), and a cruise speed of about 125 m/s. This next shot is at ~4,000M, so the speed is a little slower and the FF is a little lower. In this shot, I'm at 10% torque, still maintaining 460 rpm. Here's a shot of "Six Turning Four Burning". Running the jet engines greatly improves takeoff performance, and helps zoom you up to altitude. I have the torque tied to the main throttle, so I'm wasting gas here by running the turboprops at 100% torque- 20% would be plenty to get full power. Here's a side-view. As anyone who has built long airliners in KSP can attest, the takeoff can be tricky. If you rotate too much during takeoff, the tail of the plane hits the runway, usually leaving you with about half an airplane! On this one, I have the gear mounted low enough I can rotate to about 15 degrees without hitting the tail. Interestingly, this plane actually flies just fine even after losing everything aft of the wings! I had some CG/CL issues, which I corrected by adding Canards to the front. You can't see the canards because I rotated them into the fuselage, hiding them. But, they still work (thanks to KSP's take on aerodynamics), and have enough authority to control the pitch of the plane even after I lose the entire tail during takeoff.
  9. Yeah, those panels do look like they could be clipping. One other thing I noticed in the screenshot is the use of a fairing with a structural truss. I’ve seen some weird effects with parts mounted inside the fairing truss. I’m usually cautious with clipping in a truss fairing, especially if I’m going to be decoupling. Also, in the screenshot it looks like SAS is on, and is applying force to the vessel. Not sure if it’s trying to counteract the rotation, or is causing it. If you can shut off SAS before parts start coming off, that might be worth a try.
  10. As to the original question, here is a site which shows you the highest point and lowest point for each body: https://ksp.deringenieur.net Once you have selected a planet or moon, in the options button select 'Points of Interest'. For the few bodies I looked at, that selection displayed the high and low points. However, it appears to me the lowest point may be the deepest part of the ocean for bodies with liquid covering some of the surface (Eve, Kerbin, Laythe). It sounds like you are more interested in the high points anyway.
  11. I would adjust the landing legs. If they are too 'springy', reduce the spring strength, and increase the dampening. I would max out the dampening.
  12. Here’s one suggestion- If you happen to have a vessel in a equatorial orbit, switch to that vessel, and compare it’s inclination to your target’s. Otherwise just eyeball it. And yes, an inclination of 0.5 degrees is awesome! I’d say you have it nailed. The idea is to get on track as soon as you can, instead of spending DV going the wrong way. At 10kM you don’t have much velocity yet, so it’s still really cheap to make course corrections. Way to go!
  13. 1. Is it enough? Depends on wether you're doing gravity assists or not. I don't. I could make 2800 work, but it would not leave much margin. But, it's possible, even without gravity assists. 2. Total Fuel Cost? No idea. Again, I think you could get back to Kerbin from Bop or Pol with 2800. 3. Best tips? I rely on gravity assists when entering Jool's system. Pretty easy to get a Tylo encounter. You could get similar savings when leaving Jool, but making gravity work in your benefit is much harder when leaving. It's possible to spend hours planning a gravity-assist departure, and end up realizing you actually ended up worse off because of your efforts. I tend to count on gravity assists when entering Jool, but don't bother with gravity when leaving. 4. Heat shield? If your heat shield covers the entire craft, you should be fine aero-braking back at Kerbin. Heat shields work really well in KSP. But, just in case, do a quick-save before hitting Kerbin's atmosphere. 5. Inclination? Yes, since I depart Jool with 'brute force' instead of gravity-assists, I do try to keep my inclination on exit as low as possible. However, if you are just barely leaving Jool, and then doing a Hohman transfer, Bop's inclination is probably not going to be significant. If on the other hand you are dropping your PE to take advantage of Jool's gravity on exit, any inclination will be amplified on exit. I normally try to depart from Pol or Laythe. Departing from Bop, I would either fix my inclination first, or maybe just barely exit Jool's SOI and fix inclination then. Or, at that point, maybe gambling with a gravity-assist from say Tylo to fix inclination.
  14. Hokay! Here goes, some screenshots. Let's go to Minmus! The goal here is to launch into an orbit with an inclination close to that of Minmus. Or, whatever vessel you are trying to rendezvous with. If you are using my 'eyeball' method, I'd say anything within 10% is really good. For this example, I got lucky, and launched into an orbit about 0.1 degrees off of Minmus's inclination. I don't always get that, and I'm always really happy with any inclination within 1.0 deg. Step 1. Select Minmus as a target. This is mainly to give you some contrast in orbit colors, so you don't get confused. Step 2. Rotate Map view until you are looking edge-on at MUN's orbit. Mun's orbit should look like just a straight line, or as close as you can get it.. Step 3. Don't change your view orientation! You want to launch when the launchpad is directly under the intersection of Minmus's (or your target) orbit and Mun's orbit. It should look like the following screenshot. NOTE in this instance, I'll need to launch slightly northerly (080). If I waited about 1/2 day, I'd be on the other side of Kerbin, and would have to launch slightly southerly (100). Here's where KSC should be for your launch window. (I'm launching from KSC). Step 4. Gravity Turn! Roll over to 90 deg. just like always, but then aim for a little 'north' or 'south'. In this case I'm aiming for about 080 deg. It's hard to 'eyeball' this, and very easy to over-shoot. A little practice will make this smoother. Again, it's just like a normal gravity turn, but you're just aiming for a little north or south of 90. Step 5. Fine-tune your burn. When able, switch to map-view. I don't do this early in the launch, because there's boosters to shed early on. But as soon as I can, I switch to Map View, and look at the AN/DN values. If they are not zero (they never are..), I nudge the nose a little north or south. In this screenshot, the DN is closest to me (0.3 deg.), so I nudge the nose NORTH (towards 0) a little. In this case, with minimal effort, I was able to get the AN/DN to be 0.1 deg. That's pretty close! Again, for Minmus, anything less than 1.0 deg is 'Good Enough!' Step 6. Once you have the AN/DN as close to zero as you can get (Anything less than 1.0 deg. is just showing off!), burn Prograde, and circularize your orbit like normal. I like to shoot for about 100kM, but use whatever orbit you like. Step 7. Don't forget to deploy your solar panels and antennae! Step 8. Burn to intercept your target. If your target is a vessel, you'll want to match inclinations exactly. In this case, my target is Minmus, an inclination of 1.0 deg. or less is fine. For Minmus, I start my burn when I'm about 110 degrees behind Minmus, but you could use maneuver nodes to double-check. In the following image, Minmus is at 12 o-clock. I would start my prograde burn when I'm at about 4 o-clock. Hope this makes sense! For other orbits, the principle is the same. However, the further from 90 your target is, the more difficult it is to get within 1.0 degrees. A good goal to shoot for is an inclination of 25% or less of the original inclination. So, if your target is 20 deg. off of 90 (say 70 or 110), then if you can launch into an inclination of 5.0 deg. or less, you are doing great. For polar orbits (say 70-90 deg), if I can get within 10 or 15 degrees I am really happy with that. You could probably get closer using mods (like MechJeb), but what fun is that? Nice to be able to just 'eyeball' it, and get pretty darn close. Again, good luck!
  15. I’ll try to post some screenshots later, but here’s the method I use. For me, the inclination I’m aiming for is Minmus, so I’ll use that in my example, but should work with any orbit. I select Minmus as a target. This isn’t required, but makes my target orbit a different color. In the next step I’ll be looking at my target orbit (Minmus) and the Mun’s orbit. Having your target orbit a different color than the Mun’s makes it easier to see. Next I orient the map view so I am looking straight down at Kerbin’s equator. I’m zoomed out far enough that Mun’s orbit fits entirely in the view. Ideally, you should be looking edge-on at Mun’s orbit- in other words Mun’s orbit should just appear as a straight line, not an ellipse. I use Mun as a reference because it’s basically a perfect 90 degree reference. Ok, next step is warping to your launch window. Your launch window is when your target orbit (Minmus in my case) intercepts Mun’s orbit. When the launchpad is directly under where these two lines cross, launch! Next step is your gravity turn. You will need to determine if you need to aim for slightly less than 90 or slightly more than 90. In the case of Minmus, I aim for either 82 or 98 degrees. Heck, let’s round those to 80 and 90 degrees. During the initial climb, I’m just trying to establish a slight deviation above or below 90. Most of my launches are pretty busy below 30kM, so I can’t check my progress in map view. Once above 30kM I can usually switch to map view, and fine tune my trajectory. I’m looking at either the AN or DN value. If they’re not zero (they never are..), I bump the nose a bit north or south, to get the AN/DN values as close to zero as I can. 90% of the time I end up with less than 1.0 degree inclination difference to my target (Minmus). Anything less than 1.0 deg. is ‘close enough’, I can easily get a Minmus encounter at that point. In your case, you are trying to rendezvous with a vessel, and will eventually need to match inclinations exactly. My method will get you close, but you’ll still need to fine-tune your inclination once in orbit. I would suggest your goal should not be 100% accuracy, but to reduce your inclination burns as much as possible. Example- your target orbit is offset 20 deg. from equatorial. If you launch to an equatorial orbit (90 deg) you would need to burn Normal or Anti-Normal 20 deg. to fix that. If you can get within 5 degrees, that’s potentially a lot of fuel you just saved! I mention this because it did take me a bit of practice to start getting close to my intended inclination. I don’t use mods, so I’m relying on my ‘Mk I Eyeball’ for precision. However, I’m sure there are mods which can also aid you with this. For me, it’s more fun and challenging to just eyeball it, and pretty rewarding when I end up close! Good Luck!