EpicSpaceTroll139

That's exactly what I thought too when I saw the picture! Didn't know the exact designation mind you, I'm a bit rusty, but thought "hey that looks like one of those fancy upper level electron orbitals!"

Made Flash Gordon Kerman Good news: He was fast Bad news: He died upon tripping over a bug.

Update: a further experiment has shown reaction wheel torque to indeed be constant, therefore the efficiency should increase linearly with speed. I believe the apparent torque curve was due to stretching of the spider engines from their joints. I believe something interesting I could do is find out the moment of inertia of various parts, which could be useful for players who create various mechanical contraptions. Might be especially useful for that clock project I put on hold. Edit: Computed MOI about roll axis for a couple of parts: Flat Octo probe core: 40.59 kg*m^2 Small Reaction Wheel: 45.07 kg*m^2

I can mostly confirm this from experience. A 2x1 straight wing behaves the same as a 1x2 straight wing which behaves the same as a 2x2 Delta wing. Doesn't matter if your wings are stacked either. 4 1x½ wings stacked to look like a brick will give you the exact same lift and drag as a 1x2 wing... Kinda disappointing really. A SSTO can have same wing planform as an early biplane and fly just as well as if it were designed with proper streamlining. I also concur on the clipping of parts. Anyways, I might try my hand at this challenge sometime. Juggling projects right now lol.

Jeb being a badass as usual.

Wow you've already got it working! Seems like just yesterday you made that steam engine! I wonder if, to allow rudder inputs without switching, one could set up the yaw to be controlled by "twist" of the control stick. Of course that would probably make elimination of coupling even more hard... Something I want to try at some point... Ugh... I need to stay focused on one project at a time, but alas, that seems impossible!

Hehe I believe for like a day or so after the bigish forum update there was one. Too bad they got rid of it!

How funny! I was just reading through the physics.cfg on an unrelated quest and noticed that yesterday. I thought that was strange too. Might run some tests myself when I get the chance. I think setting it lower is a good idea though.

Good Lord Azimech... How do you plan to control everything? We don't exactly have giant people in KSP to manipulate the various controls. Are you planning on connecting all the controls to the stick, or will you have to frantically switch back and forth between yaw pedals, the control stick, throttle, and flap lever when taking off and landing?

It's only electric stock props that exploit the broken reaction wheel. Stock turboprops are completely fine as far as the physics go. I really doubt that Squad will fix the reaction wheels, as it would mean that pretty much all spacecrafts would need RCS to deal with reaction wheel saturation, and thus very people would even bother using the reaction wheels. Either that or they would repeatedly use timewarp to get rid of rotation after unsaturating the reaction wheel. The reaction wheels would also need to have large power draws to get reasonable turn rates. Seems pretty needless for a game that's supposed to be fun, and just to prevent the odd person from making a stock electric plane that exploits physics a bit.

A note to start off: This is quite a long post with stuff that might be boring for some of you. If you just want to know the conclusion, skip to the end. So this all started while I was reading through this thread in the game-play questions. Being a bit of a turbohead myself, I figured I could help out at least a little bit with the aerodynamic efficiency of the propellers, even if electric engine types weren’t really my thing. As I read through, I encountered @Geschosskopf who believed from his extensive experience with Kraken and Ladder drives, as well as his (excellent as you will find out) spidey senses for potato physics that stock propellers must exploit physics somehow, his hypothesis being that they were taking advantage of some kind of artifact of the game’s collision physics that ignored Newton's 2nd and 3rd laws. The idea being that the propeller was dragging the plane along without “feeling” the plane. The very good reasons for this idea are summed up in the following argument. “How many RTGs do you put on a shaft? 4-6 at most, maybe less? Each RTG makes 0.8 EC/sec. The accepted conversion rate to real units is 1 EC = 1 kJ, so 1 EC/sec = 1 kW ~ 1 hp. Thus, you're only putting 3.2-4.8 hp into the shaft, which is the about what you get from a small lawnmower engine. How are you even going to taxi, let alone fly, a multi-ton aircraft with that little power?” - Geschosskopf I knew ladder drives and kraken drives took advantage of some strange physics, but I couldn’t wrap my mind around the idea that the physics of collisions between basic craft (like the propeller shaft and the plane) could be messing with things, because that would imply some very wonky effects would be seen any time two crafts were in contact. That being said, I may have been a bit biased since I regularly work on stock turboshaft helicopters. We struck up a lively debate in a private chat, which took place over the course of 3 days. His arguments usually went into the workings of the game, looking at how it (probably) models collision, trying to insure that the collision meshes two parts on different vessels are not clipping into each-other, and moving them a bit if they are. Meanwhile mine usually stayed more on the player side of things, using thought experiments such as a caged jet (this will be followed up on later) to show why it didn't make sense that the propeller was pulling the plane in ignorance of Newton's 2nd and 3rd laws. Eventually I decided to actually run a few KSP experiments to determine the viability of the wonky physics idea, and otherwise determine what was going on. The first experiment was with a Mallard carrying an orange tank. The Mallard had the orange tank inside the cargo bay mounted on a decoupler, with cubic struts and I-beams positioned around it so as to act as a cradle for the orange tank, preventing it from moving when decoupled. The configuration can be seen here. The idea being that, if collision physics work properly, the plane should take off at exactly the same speed if the orange tank remains attached to the plane as if I decouple the orange tank and let the cradle of cubic struts keep it from moving. If the collision physics are wonky like Geschosskopf theorized, then the plane should take off at a lower speed when the orange tank is decoupled, because the game will think the plane is only lifting itself, and will only teleport the tank along to prevent clipping. I made the first run with the orange tank still directly attached to the aircraft. I was a little late with the screenshot, but it took off at 76.1m/s. I made the second run with the orange tank decoupled and held in the cradle. I made this screenshot on-time to see the takeoff once again at 76.1m/s. Exactly the same as the previous takeoff. Sequential trials produced almost identical results, thus appearing to imply that the collision physics worked properly, obeying Newton’s 2nd and 3rd laws. But I wanted to be extra sure, so I devised a second experiment. The second experiment I called the “Caged Jet Experiment”. The idea was to simulate the pushing of a stock propeller on an airframe using a jet engine. Just in the same way a prop-shaft is restrained to the airframe of a stock plane or helicopter by a bearing, a jet engine would be restrained to the airframe of a Mallard by a “cage” once again composed of cubic struts. The idea being that a jet engine would stand in for a propeller shaft. If the collision effects ignore Newton’s 2nd and 3rd laws in the way Geoschosskopf theorized, then a jet held in a cage should make the plane move much faster than one directly attached to the plane, because the jet engine doesn’t realize that it is pushing the big heavy plane. I didn’t take many pictures of this one because I didn’t have an autopilot installed to allow me to hold a certain altitude precisely, so as to be able to quantitatively measure the performance of the plane. However I testify that it performed nearly if not exactly the same when the engines were decoupled and trapped in the cages as when they were still directly connected to the plane. The only difference was that with the decoupled engines, I could not reduce throttle for landing afterwards. Good thing the Mallard was a seaplane! Another experiment I proposed, but did not perform, was to attach a 5 ton trailer to a 3 ton rover using a stock pin-in-hole joint. If the collision physics work correctly, the setup should behave exactly like what it is. A rover pulling a heavy trailer, with all the associated performance losses. However if the collision physics are wonky, the rover should still have the same performance as if it were driving on its own, and pull the trailer along as if it is nothing. I’m guessing the people I see on here building semi trucks every now and then that a truck most definitely is affected by carrying a trailer behind it. So, the collision physics didn’t seem to be the root of the problem, so another idea came up. That was that KSP didn’t know how to properly get the thrust of a stock propeller, however this was quickly disproved by the point that a propeller is quite literally a number of wings moving a circle. KSP doesn’t have to do anything to find the thrust of a propeller or lift of a rotor that it doesn’t have to do to find the lift of a plane going into a slip-turn. So then there was my hypothesis that the 1EC = 1kJ standard was incorrect. I devised an experiment to try to prove or disprove this. So how it went in my head was that I would measure the torque output of a reaction wheel in relation to the angular velocity. Using these values I could determine the power output by the equation power = torque x angular velocity (P = τω). By comparing this to the electricity drawn (EC/s) by the reaction wheel, I could find the energy content of a unit of electricity. For the experiment I created a kOS script which can read the angular velocity, and use that to determine various other statistics. I also created a special vessel with which to perform the experiment There is a probe core, a fuel tank, a reaction wheel (the 0.625m type, which has a constant electric charge draw of 0.25 EC/s), and two spider engines on the sides directed so as to create torque. The engines are a known constant source of torque, calculated to be 7740 newton-meters. So what the script does is activate the engines, and then take a reading of the angular velocity and labels it Ang_vel0 at a time desginated T0. It then waits a short period, and measures the angular velocity and labels it Ang_vel1 and takes the time as T1. It can now calculate the angular acceleration as (Ang_Vel1 - Ang_Vel0)/(T1 - T0). It can then calculate the moment of inertia of the craft in the roll axis using α = τ/I => I = τ/α. Moment of Inertia = Torque / Angular Acceleration Note that I use the infinite propellant cheat during this experiment to make sure the moment of inertia doesn't change as the engines fire. Anyways, so the script shuts off the engines again, since it needs no disturbances for the next part of the experiment. I use timewarp to bring the spin back to a halt, so as to have no influence from the previous bit that determined the moment of inertia. The script now locks the ship's roll control to full clockwise (would work counterclockwise just as well, that's just what I picked), and uses the same procedure of finding angular acceleration using = (Ang_Vel1 - Ang_Vel0)/(T1 - T0). It displays this value as well as the angular velocity** Since it now already knows the moment of inertia, it runs it the other way to find what torque the reaction wheel is producing. τ = I*α It displays this value** Now with the torque and the angular velocity, it can calculate power via P = τ*ω It displays this value** **All these are updated over time, allowing changes to be observed By plugging all the displayed values into a spreadsheet, I was able to create charts displaying various items such as torque curves. To my intrigue, at near-zero angular velocity, the 1EC = 1kJ conversion rate was true (so in the graph I put EC/s as W for watts), but as angular velocity increased, the reaction wheel appeared to be developing more and more power from the same constant power input. I and probably a lot of people here knew reaction wheels were broken due to lack of conservation of momentum, but this demonstrates just how badly they are broken. At just 9 radians per second, the reaction wheel is multiplying the power input by a factor of 150. Thus you can give an electric plane spitfire performance with the electric power equivalent of dinky little lawnmower. I have yet to perform the experiment up higher angular velocities, however it would be interesting to see how the trends continue. I want to add some more tests into the experiment as, now that I think about it, I'm wondering if torque is actually constant, and the apparent change is due to the spider engines stretching away from the tank due to centrifugal forces, thus changing the moment of inertia slightly. Perhaps I can devise a method of testing that does not require any off-axis parts.* Current conclusion: Stock propellers in of themselves are not exploitative, however electric props take advantage of broken reaction wheel physics to generate power a couple orders of magnitude greater than what is put in! So neither Geschosskopf nor I were entirely correct! *Update: After further testing using a reaction wheel and a tank with no radial engines, I have found that the torque output of reaction wheels is constant. Using this I plan to calculate the MOI of numerous parts, which could be useful for the construction of mechanical contraptions. Thanks for reading! Also thank you Geschosskopf for the fun debate and the push to question the workings of the game. This all was quite interesting to work out. For anyone interested in examining the script I used you can find it below. The order of the display of values and their labels have been modified slightly to be more user-friendly, but all the math is the same. Not that the variable labeled "Torque" is used twice in the script. In the first section it is a fixed value, designating the torque from the two engines. In the second section it is overwritten and is the calculated torque output of the reaction wheel.

Nice work! Beena while since I built a jet with an ejector seat. I know I made one once... Dunno when, or what it was called though xD. Didn't have an ejectable canopy however.

Well, I suppose yours does kind of look like a 1930's locomotive (which is just cool imo as a 1860s one) if you look at it from the side or the back, but the sort of double boiler and cylinders hidden inside kind of threw me off. I think the weird face it appears to have from the back is rather amusing though. Great machine regardless!

Nice work dude! I love it! Gotta make one of these myself! Not sure, I need to do testing myself, but it appears that your steam engine has better performance while klond's has the looks* (it doesn't have the firebox though). Now what we need to do is combine the two. *Not saying yours is ugly, but to be honest klond's looks more like classic steam engine

An update on this. Through a long private chat debate and some physics experiments in KSP, we have come to a conclusion that neither of us were entirely correct. Expect a fully fledged post on some interesting KSP experiments that demonstrates that stock props in of themselves do not violate physics, but reaction wheels break physics even worse than we thought! @lgsolaris I believe most of the turboprops and helicopters you'll find here are up to date (except perhaps a couple of the really clunky looking (no offense Azi) planes and helis in the first post, which were some of the first turboprops and turboshaft ever made) and will work in the current version of KSP. I myself have not used the new RCS ball bearing much, mostly because I haven't dedicated much time to learning how to make one reliably. They appear simple enough that I could probably figure it out if I tried, but for my mechanical contraptions the solar panel - antenna bearing has been sufficient, so I haven't felt a strong urge to switch over. If I built more planes, which tend to have higher bearing stresses, I would probably have already switched. @klond and @Azimech might be able to help you with those. Anyways, from my experience with turboprops planes, I would make sure I have a good sized wingspan with my landing gear placed as far out as possible to help deal with the torque. You'll probably want to trim using alt-q or alt-e against the torque, though remember you will need less trim when you get up to speed. Once you've got those you need to fiddle with the number of blades and the blade pitch quite a lot to find the configuration that gets the best thrust from your propeller. It's a lot of trial and error, but it's so rewarding when it finally works! Edit: you can find many working turboprops and helicopters here https://kerbalx.com/hangars/6515

This is fantastic!

This stuff actually happened last night. I've been pretty busy today with schoolwork. By uprating the engines, something I often do for replicas*, the main rotor on my CH-53E can now lift itself in the air with its main rotor. I'm having trouble getting the tail rotor spin fast enough to provide adequate antitorque however, and I haven't added any reaction wheels or other attitude control systems, so it just spins out of control and flips out. *I do this on my replicas because I make them using stock parts not for the sake of showing what as possible with stock capabilities, but for the sake of them being loadable for players without mods. Thus I strive for the lowest part count for the level of detail I want. I do not use the same philosophy for my non-replica builds, and thus they do not have hacked/uprated parts in their craft files.

I'd suggest first making a prop plane that can fly on Kerbin before trying to make one that works on Eve. You might think it would be easier to make something fly with Eve's thick atmosphere, but that thick atmosphere makes it a lot harder to get good rpm on the prop. Kerbin can give you practice, then double or maybe even quadruple the torque for Eve. I haven't made anything other than a helicopter style thingy work on Eve (it crashed like 5 seconds after take off due to inadequate stability control), but that's mostly because I haven't invested a lot of effort. I'd suggest fewer and possibly slightly longer blades on those props too. It might seem like more blades = more thrust, but past a certain point the drag results in lower rpm and thus less lift --> thrust.

I was a bit perplexed by the argument that the game physics results in the propeller shoving the plane in a way that violates Newton's 2nd and 3rd laws. If that we're true, then I could also fly a larger jet plane with smaller engines by decoupling my engines and keeping them captive in cages... But that doesn't work at all.

Sounds like neat idea. Perhaps cubic and octagonal struts would be good interface pieces because, due to their "physics less" nature, joints between them don't bend, so you could string several components together and have them act as one rigid component. I've been regularly using a subassembly version of the thermo-rcs hinge cage component on a cubic strut. Might dig that out and see if that can be useful.

Unless you're using FAR, make sure to build that door really strong, because stock aerodynamics will try to rip it off the back. Good luck with that though! Edit: I wonder, will that thing even need wings? I can imagine that wing panel fuselage makes quite a bit of lift already!

Progress on the 53E: I'd say, ehh... 75% done? I need the tail rotor bearing/power mechanism(s). I'll probably use thermo-rcs bearings for that. Then I need to make the ramp. Currently debating whether to make it movable or not. It would be nice, but the part count is already at 350 or something like that. Anyways, after those things, I'll try and see if I can get it to fly, and perhaps add pitot tubes, antennas, and other doodads and it'll be finished.

I once attempted to make something like that out of a static model someone had made on KerbalX. It didn't take long for me to abandon that endeavor though. Good luck making that work! Speaking of abandoned endeavors, I decided to take a break from racecars and clocks, and work on this neglected thing: I estimate she's about 50% complete. Cockpit needs some work, most of the tail needs to be built, tail rotor drive and bearings too. Then I need to figure out how to move the center of mass several meters forward (without making it significantly heavier) before I can even think about tinkering with the turbomachinery so it can (hopefully) fly. Making this thing fly isn't going to be easy. It's gonna be fairly hefty and draggy with all the detailing and whatnot, and the turbine wheel is smaller than what I usually deal with, thus meaning I will get less torque per blower. Torque will be important given the high moment of inertia of the 7-bladed main rotor, something which will probably cause all sorts gyroscopic control problems. When (if) it flies, it will almost certainly have the flight characteristics of a hippopotamus. Edit: @KandoKris At the top of the text box when you're creating or editing a post, among other things, there should be a symbol that looks like an eye. If you click/tap on it, it will create a spoiler box inside which you can put text and pictures. No need for bbcode.

Made some upgrades to my Selenium I racer, since my lap time only lasted a day. It is however proving rather hard to keep it stuck firmly to the ground. Usually the problem is just losing traction on a corner and spinning out, but other times... Note: kOS dashboard readout is nonsense now that the computer (probe) core is detached from the vehicle. Guess I might take a break from cars and work on my clock, or my Saturn V replica... or something

Believe it or not they do exist! @Sandworm congrats on your career progress! I wish you the best of luck with becoming a pilot! Keep us updated!