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So, I got this DLC wanting to make helicopters. I found out pretty fast that metaphorically bought the tool, but not the skill. Yet. The DLC has a few stock "helicopters" which are just ducted-fan VTOLs and flying platforms. However, I'm trying to make a "conventional helicopter" so to say. A helicopter with a main rotor and a smaller tail rotor. So far, my results have been far from desirable. My first rotor-tail rotor helicopter design (image links below) was awful. All it did was break itself. https://prnt.sc/tsxyu0 http://prntscr.com/tsxz61 What's the right way to make a rotor-tail rotor helicopter?

Design a SSTO that uses propellers or rotors instead of jets during atmospheric ascent I like useful challenges, and I hope this one may be considered as such. The goal, besides challenging oneself, is to create a new type of SSTO that can explore atmospheres with props or rotors, thereby saving fuel and enabling the exploration of oxygen-free bodies, like Duna. This would enable a craft to biome-hop for science or transport resources much more effectively than slow rovers and fuel-guzzling rocket planes/landers can in said atmospheres. While these kinds of biome-hopping and transport crafts do exist, they don't seem to exist in reusable SSTO form, it seems. Props and rotors, unlike jets and intakes, also have the benefit of not being dead weight on Duna. So while props may offer worse performance on Kerbin, they'll pay you back during Duna ascent. Or at least, that's the theory. Requirements: No airbreathing engines. The craft must be capable of flight using rotor/prop power alone in the destination planet’s atmosphere, but you can obviously use rockets to get to and fly in space. Self-sufficient SSTOs only. So, ISRU mining is allowed, but no assistance from external ships (asteroids are OK). You may not jettison any parts other than payloads that don’t help the main vessel in any way. Normal difficulty or harder, but for convenience, you may ignore commnet—pretend a network is already in place. The SSTO must be useful in career mode. There’s no point in a spacecraft if you can’t bring any Science, Kerbals, or payloads along. Carry at least one kerbal (chairs allowed), OR if you wish not to carry kerbals, carry at least 0.2 tons of parts from the “science” category, OR deliver a payload weighing at least 0.5 tons. You may drop payloads once you are landed at your destination. If your destination is Jool, you may drop it low Jool orbit or into the depths of Jool. Payloads must be attached/detached using docking ports, not decouplers. No mods or part tweaks other than official DLCs, FAR, aesthetic mods, and piloting or planning assists. Challenge Tiers: Tier 0: "Proof of Concept" (Normal): Build a prop/rotor SSTO that makes it to Kerbin orbit. Must be capable of takeoff/landing in Kerbin’s atmosphere on rotor/prop power alone. Example: Reddit user u/chargan’s Orbital Chopper Tier 1: "Practical Problems, Sober Solutions" (Hard): Fly your prop/rotor SSTO to Duna's surface and back. Must be capable of takeoff/landing in Duna’s atmosphere on rotor/prop power alone. The challenge is simple in concept, but hard in practice. But, if you manage to accomplish Duna, there are other destinations to try, where almost no SSTO crafts have ever gone before... Bonus Badges: Within each tier, entries can receive the following awards. Ordered roughly by importance in career mode. (ISRU comes last as you are strongly encouraged to use it.) V: Heaviest payload delivered IV: Greatest tourist capacity (No chairs - tourists can’t go on EVA) III: Cheapest craft II: Lightest craft (Wet mass, excluding payload mass) I: No ISRU (Multiple entries can earn this.) Leaderboard: Good luck! If you have any trouble completing the challenge, browse this thread or just ask for help—there are many posts here with tips and links and instructions.

The primary feature of the DLC is, of course, that you can assign some variables for rotors and servos, such as target angle, target RPM, target torque, etc. as dependent variables in the KAL-1000 controller, where the independent variable is the play position of the controller. It is also possible to slave the play position to any of the game's available axes (main throttle, translatory controls, standard flight controls, etc). I am curious as to whether this relationship can be inverted - that is, whether the play position of a controller can be determined by, chiefly, the current angle of a rotor or servo, though I'm sure the other variables would have some uses. If this is not possible in normal KSP, is there a mod that provides a similar function? I ask this because, if this is possible, it may finally allow some aspects of lift dissymmetry to be solved.

What's going on: having KVV and RCS Build Aid active at the same time draws the standard coordinate axes (longitudinal, lateral, vertical) through the COM, in both the screencap previewer and the build scene. You can use the previewer in KVV and watch as you manipulate whatever part you need to manipulate to move the rotors about: the preview and build scene will update the axial lines as the COM moves live as you move the part/s as well. Orthographic view in KVV squashes everything in the previewer into a 2D plane perpendicular to the viewpoint, which greatly assists in getting things lined up. Please note that the lines will only draw through the COM, despite RCS Build Aid being able to track the ACOM and DCOM. For quadcopters/tandem birotor craft, the crossmarks through the axes can be used to gauge distance from the COM to balance things out without using differential thrust. I am not sure if having Hangar Grid is essential in getting the lines to draw (as can be seen in my mod toolbar), as it draws its own guide lines for part rotational assistance.

TLDR I did some tests with various rotors to determine which yields the highest lift/weight ratio for heavy payloads on either Kerbin or Eve. In the static tests I’ve performed on the ground of Kerbin and Eve, I noticed that the large helicopter Type S blades provide the most lift per tonnes rotors+motor . In my flawed tests, 8 rotors per motor work best on Kerbin and 4 rotors per motor work best on Eve. I was also able to roughly determine the maximum mass of a craft at which it would still fly. Long story I’ve been running tests with various sizes of propellers to determine the a correlation between vertical lift and mass. I’m especially looking for optimum mass to lift ratio’s for heavy crafts and trying to find a way to calculate the amount of propellers I need to get something in the air. I’ve been trying to approach it scientifically but eventually just tried some stuff at random. Literature study None.. just felt like messing around with the propellers. There are probably a bunch of better articles describing how to calculate the amount of lift on a given planet at a certain altitude. My initiial guess is that the lift is calculated something like: Lift = Function [ rotating speed, angle of attack, air density, rotor blade type] Experimental setup I performed two experiments: 1. On Kerbin , using a rigid clamped setup with 3 heavy motors in series. I tested 3 types of rotors with 8, 4 or 2 blades per motor 2. On Eve, using a massive s4 fuel tank setup ( 1,200 tonnes) with 4 motors. Testing 2 rotors, with either 8, 6, 4 or 2 blades per motor Results The current measurements have been done under static conditions on kerbin and Eve. Below you find the results. Propeller type Amount of props on motor Total weight of props (ton) Weight Motor (ton) Max RPM optimal Angle of attack Planet Lift (kN/prop) Total lift (kN) Lift/total weight motor + rotors (kN/ton) Heli S-Type 8 1.44 2,2 440 5 Kerbin 270 2160 593 Heli S- type 4 0.72 2.2 445 8 Kerbin 335 1340 459 Heli S- type 2 0.36 2.2 450 8 Kerbin 346 692 270 Propeller S type 8 0.96 2,2 460 82 Kerbin 34 272 86 R-25 fan 8 0.96 2,2 460 84 Kerbin 37 296 94 Heli S-type 8 1.44 2,2 253 5 Eve 403 3224 886 R-25-fan 8 0.96 2,2 450 84 Eve 163 1304 413 Heli S-type 6 1.08 2,2 253 3 Eve 500 3000+ 915 Heli S-type 4 0.72 2,2 418 3 Eve 700 2800 959 Heli S-type 2 0.36 2,2 450 3 Eve 1100 2200 859 I changed the angle of attack to find the optimum angle at which most lift was created. From these short tests, I found that the Heli S-type blades performed the best when you look at lift per weight ratio. I also tested if less rotors would yield in better performance on either Kerbin or Eve. From what I’ve measured I could state that: 1. On kerbin 8 Type S Helicopter blades performed better than less blades 2. On Eve, the optimum lift/ton motor+rotors weight seems to be 4 rotos per large motor Discussion One of the things I wanted to find out If I could calculate the maximum weight a certain setup would be able to lift. From what I’ve conducted. It’s fairly easy to calculate: m = max mass (in tonnes) = F * G F = Lift (kN) G= gravitational force ( 9,81 for kerbin, and 16,5 on Eve). For a two motor helicopter with 4 large helicopter type s blades per motor, this would mean that it could carry: 2800kN / 16,5 m/s^2 * 2 motor with 4 props = ~336 tonnes I tested this and It seems to check out. I also wondered if I could translate tests on kerbin to match the results on Eve. It seems that the there is a correlation between air density, RPM and lift on Kerbin. However, the maximum amount of RPM is different on Eve, compared to kerbin, so I think I need to add torque and drag into the equation for this. I didn’t have time to work this out though. Btw, this was a very flawed study and many additional tests need to be done before any hard conclusion can be made. Several things come to mind: - Does the lift vary with different vertical velocities (anything else than 0 m/s)? - Does the optimum angle of attack vary as the density changes (it does) - What is the effect of the angle of the ship on the optimal angle of attack of the blades - Etc.. Anywho… It was a nice experiment. I’m now able to calculate how many rotors I need to carry a certain payload.

I thought this might interest a few of the propeller veterans Here's a highlight I exported from last nights stream: Craft file: https://www.dropbox.com/s/dun4pe5g1xu632d/! TR6-SemiCyclicGimbal I - LiftTest.craft?dl=0 This started out as a PM with @Azimech and after some interesting ideas from @luizopiloto regarding using klaws and some TWR calculating wizardry by @SumGuy and a few others who popped up in stream, I've come up with that I might call the most ridiculous advanced full stock propeller to date. There's two main factors being used in each engine: (1)The two klaws tucked inside the cargo bays, and (2)the six klaws holding each fan blade. The klaws in the bay are used to add some extra sway to the engine while still being able to hold 250+ tons. They act as a "gimbal" of sorts letting the engine move left/right and up/down but without rotating. The klaws connected to each fan blade let the blade pivot around freely. This lets each blade change it's pitch depending on where it is in the spin cycle, tilting up when it's at the bottom and down when it's at the top like a swash plate. Since klaws don't rotate the angle of each blade is kept the same.