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Everything posted by Dinlink

  1. If by "Obeth" you mean the amount of DV you need to change your peri or apoapsis, I usually use the instantaneus orbital speed equation [Orbital Speed] Given your ship be positioned at the periapsis or apoapsis (r=PE+R or AP+R), and you can calculate your actual semi-major axis (a = (PE+AP+2R)/2) , then you can obtain how much speed would you have to add or remove from your PE or AP to change the other one... For example, you are at periapsis of 70km on Kerbin Orbit with AP of 100km ... And you want to circularize and bring your AP down to 70km: Kerbin radius R = 600km Kerbin Standard gravitational parameter \mu = 3.5316000×1012 m3/s2 Your actual semi-major axis a = (70+100+1200)km/2 = 685km Then your actual speed at PE in your actual orbit is: Vi~ sqrt(3.53e12*(2/670e3 - 1/685e3)) = 2320m/s Given that your PE will not change if you change your speed fast enough at PE, only AP will change, then the speed that you should have at PE for a circular orbit can be calculated given the semi major axis a= (70+70+1200)km/2 =670km Vf~sqrt(3.53e12*(2/670e3 - 1/670e3)) = sqrt(3.53e12/670e3) = 2295m/s Which means that you would need to reduce your speed from 2320m/s to 2295m/s burning retrograde at PE, consuming 25 m/s of DV
  2. Could you "orbit" Minecraft? Assuming that the max size of the map is a differential slice of the surface of a gigantic spherical body... So we can justify it being flat... What would be it's radius? It's density? ...
  3. Is true that in the Ostrogoth article "Astronomy" is not mentioned, I thought it would because many ancient tribes practiced it... What I understood by the rule above was to have a continuous thread of linked words from article to article to simulate when you start reading a wiki article and click on a link in a word on that article and repeat the process until you find yourself on an unrelated article... I guess ppl understand this rule different than me.
  4. I don't know which Star article are you using, but clearly is not the one in the line "Ostrogoth" >> "Astronomy" >> "Stars" I can't find your quote on the Star article: https://en.m.wikipedia.org/wiki/Star
  5. I will take it from the Star wiki article that follows the Astronomy one, given that "Reasonably Priced Cars" is not in the Star article. From Star article --> Jeans instability
  6. I would like to point out some details on the origin of subsonic lift phenomena: - When explaining lift everyone centers around describing how airfoils are able to deflect the flow field and hence, cause a pressure difference... But very little try to explain why... Why an obstacle on the flow field is capable of deflecting it at subsonic speeds... - Turbulence... airfoils works in turbulent régime Indeed, turbulence is not the same as boundary layer detachment, which is the culprit of lift loss. Turbulence is a flow regime where inertial forces are higher than viscous ones (High Reynolds number) and hence the flow becomes unstable and create a cascade of swirls, big to small, to the smallest at molecular level where energy is dissipated (Kolmogorov scale)... This disordered regime appears almost from the leading edge (front tip) of the airfoils on normal conditions... Only at very low speed the laminar-turbulent transition can be delayed... Or even you can have a full laminar flow regime in very small flying animals or in very viscous media... - The magic is all due to the viscous boundary layer, the fundamental phenomenon ignored by most science educators. If your remove viscosity completely, lift becomes impossible, no shape would be able to create any lift at any subsonic speed... It's called potential flow, and has exact mathematical solution. When you add a little bit of viscosity, even a very small amount, viscous effets become very important very close to the walls, this viscous effects create "detachments" of the flow, that means, the flow instead of following the walls of the profile and go around the edges as they would in potential flow, they detach. When the flow is below the airfoil (at the intrados) and tries to go around the trailing edge (rear tip) as it would in potential flow, it detaches, causing a depressions that guides the flow on the upper side of the airfoil to the trailing edge, causing the deflection and hence the lift... No viscosity, no lift... But it can be detrimental too, if the angle of attack is too high, the flow can detach trying to go around the leading edge, creating a big recirculation zone on the upper side (extrados), and causing the upper side of the flow to ignore the curvature of the airfoil and pass straight, destroying the deflection and hence the lift. This can also be observed on laminar regime and is called "laminar recirculation Bubble". I hope these explanations helps to clarify some confusions that can arise from the information found on the internet about the origin of lift. PS. I would like to add a Direct Numerical simulation of an airfoil in a slow flying glider, showing the laminar - turbulent transition and the corresponding turbulent flow on the extrados, intrados and wake. The trailing edge detachment zone is shown too (incipient separation). Hope this serve as complement to the explanations above.
  7. I would second everyone who said aerodynamics!... It would be nice to see something like Ferram Aerospace mod but with a better User Interface integration :). I would add that a DLC with N-Body dynamics with a better User Interface than Principa mod would be really nice too!.
  8. 3168 -- average rate ~8.36posts/day -- time left ~ 32 years Given the average rate of posting in this thread to this very moment... assuming it will not get any better, it will reach the 100,000 post in ~32 years xD. Calculations: ~ 379 days have passed from Friday, 23 July 2021 to this day. The average post rate is 3,167posts/379days ~ 8.36posts/days The time left = (100,000 - 3,167)posts/(8.36posts/day) ~ 32 years
  9. I think it would be nice to add a Hardcore option or DLC that enables proper n-body dynamics and proper aerodynamics (With better interface and UI integration than Principa and Ferram Aerospace mods)
  10. I have spend several days and +1MM funds in hard mode with Ferram Aerospace mod trying to make a 30 parts nuclear rocket propelled airplane (+5000 DV) without success... I can't take off because stability issues xD... I will keep trying until game bankruptcy xD... That's the most time and funds I have spend in a project... And is still ongoing
  11. Hello!, As mentioned before, a good way would be to build an automated rescue vehicle, that's basically a rocket, capable of landing on the Mun, with an empty cabin and a core probe... For an easy and safe landing on the Mun, I would recommend to get in low orbit (10k above moon sea level) with the proper inclination so that your orbit pass just above the landing spot... When close to your target landing spot, plan to kill all the horizontal (orbital) velocity when flying above the stranded Kerbal... That way your automated rescue vehicle will fall almost vertically near your stranded Kerbal... And you can easily control the slowing down for the landing ... I would recommend to have about 700m/s of DV for the landing and another 700m/s for the take off to low orbit... Hope you find this useful, and have fun rescuing Kerbals!
  12. Ok, I will add my recommendations for a perfect rendez-vous : 1) As said previously, match the orbital inclination of the Target vessel 2) Make sure your orbit crosses the orbit of the target vessel, changing your apo/peri apsis 3) Now, the interesting part: plan a manouver near one of the points where orbits crosses, having the targe vessel as target, plan a prograde manouver until the markers meet... Move your manouver around the crossing of the orbits until the markers meets on the crossing of the orbits... That way you can plan a rendez-vous as close as possible... I recommend to plan it for the closest approach... About a couple of hundreds of meters... 0.1-0.4 km 4) Execute the prograde manouver 5) Check the markers after removing the executed manouver, and fine tune to get the closest approach with small pro/retro grade burns 6) Sit and wait one Orbit until both vessels are about to meet, then change navball to target mode and point retrograde... When getting closer (about a kilometer) start burning and reduce your speed to a couple of m/s ... When close to some hundreds of meters burn retrograde to your target until getting 0m/s ... 7) Finally, point towards your target and burn to get 1-3m/s... When been about 20-40m of your target, burn retrograde in target mode to 0m/s again... Now you can point each vessel to each other if you plan a nose-to-nose docking... Or you can use your RCS for more complicated dockings Hope this can help you!, Have fun having rendez-vous !
  13. I would love to buy that keyboard, but in a Royal Kludge 61 layout
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