Jump to content

Wemb

Members
  • Posts

    268
  • Joined

  • Last visited

Everything posted by Wemb

  1. Perhaps I'm misunderstanding your question - but when you're planning your Minmus burn, you can right click and 'focus view' onto Minmus, zoom in and, assuming you've unlocked patched conics in the Tracking Station, see your end-path past minmus - so you can adjust your angle of entry by small adjustments to your burn then. Or by mid-course corrections. Wemb
  2. I'm enjoying the contraption I recently built (based on ) with KAS to help me do refueling at my Minmus mine. It's a small probe core, with two small RCS tanks on each ends, and docking ports on those. One end is connected, via a connection point and winch to the fuel dump, and the other is left free - I can then fly the little robot to my ship, plug it into a docking port and then pump the fuel and RCS in as needed. It's only randomly exploded on me once so far - and flying it, in gravity, is a bit tricky, but can be done with fine control and careful toggling of the RCS and reaction wheels. Wemb
  3. Be glad it's only a satellite - I got into this situation trying to bring a class-C asteroid into Minumus orbit and ended up having the rock orbit Kerbin in the opposite direction to Minmus. Had to send another four asteroid wrangler ships out there to turn the bugger around... Wemb Wemb
  4. Directly editing the save game? BTW - if you've got anything with Mk16 parachutes on it, you'll need to tweak their opening altitude as well. Wemb
  5. The trouble is that isn't a thing - you want 20kNM of torque per 5 tonnes of mass at some distance away from you to accelerate your rotation by x rotations per second. Having said that, I had a second look at the picture you posted and am pretty confident that, given your ship's size and, assuming all those orange tanks are full, then the optimal number of Advanced Reaction Wheels you should fit, at the CoM, would be 'all of them'. Or, alternatively, just consider rotating the university around your ship instead. It won't be any less expensive, but the maths might be easier. Wemb
  6. Oh boy - okay - well, your ship is vaguely long and thin - the formula for I in that case is I= 1/12 ML^2 - though, in reality, yours is clearly not uniform and has more mass at the end of one end that the other does - but still, that'll roughly give you the I. The equivalent of Newton's second law for rotational systems is Where alpha is the rotational acceleration in radians per second per second. (A radian is ~57 degrees, there are 2 pi radians in a circle). So to get your ship spinning at 1rpm from 0 rpm in 150 seconds you'd need to calculate for a value of alpha of Your value of I, using the above forumla will be too low - since most of your mass is at the end of the ship, not distributed evenly. I wouldn't also assume that KSP doesn't play tricks with the calculations for this kind of stuff either - if it's a problem for us to work out, KSP may also make some simplifications in it's modelling. Wemb
  7. Okay, so this means your ship will have uniform denisty - but it doesn't say anything about the shape.. The torque needed to rotation a long thing object about it's longitudional axis (e.g. the roll of a rocket) is obviosily a lot less than that needed to turn it 180deg around. If you can think of your ship as vaguely spherical, then the MoI is But you haven't really said what you're trying to calculate - -any- reaction wheel will rotate any size spaceship to whatever RPM you wish. Eventually.. What sort of RPM are you trying to get your ship to rotate at and how fast to you want it to accelerate to that RPM? As said, non-trivial. Wemb
  8. Yes, Luckless ninja's me - you can calculate this - but you need to know the mass distribution of your rocket, do some integration to work out Moment of Inertia to work out how much torque is needed to get it up to a desired rotational speed in a desired timescale. Not a trivial calculation. - As he said, put the Reaction Wheels near to the CoM to help you rotate it. You can put thrusters as the extremities to rotate a ship quickly - but that will possibly screw you up if you ever want to use them for lateral movement instead. Wemb
  9. Think about where the center of mass is? What happens when cars turn corners - and how that affects what will eventually happen to them if they start to topple? When you turn in a vehicle, you're producing a sideways force. As your center of mass is above the ground this creates a torque and thus an upward lift on one side of the vehicle - if this gets too big, you'll flip. Or, if your on Minmus, if you go over a pebble, you'll flip. If your CoM was below the surface of the ground the torque would act in the opposite direction - gluing you to the ground the harder and faster you turn. I suppose, eventually, you'll 'produce enough downforce to 'crash' into the surface - but the crash resistance of the wheels is pretty big, especailly compared to that of gravity in places where you really could do with more downforce. Ah! Here you go - found a video: Wemb
  10. Hello again - had a quick look at the tutorial, and while I've not played it all the way through, I can tell you my Hohmann transfer cost me 170 dV - if yours is costing 700 then whatever it is you're doing isn't a Hohmann transfer... You aim with those is the end up - at the point of closest approach - to be in teh same orbit as the target. You won't be going at the same speed - (if you were you wouldn't need to match velocities) - but your orbit should be tangential to the targets when you meet. For instance, after you've completed your transfer burn, but before your circularise when you meet the target, your orbit should be eliptical and look something vaguely like this. Here the target is Mars from the Earth's orbit around the Sun. If your Hohmann trasnfer doesn't look like this, it's not a Hohmann transfer, and that's where you're spending all your fuel. A point to note about them is that while they're efficient, they're not the quickest way to get somewhere - usually you have to time them just right with respent to where you and your target are in relation to each other. The timing is everything - the shape of the trajectory, though, will always look like the above. Wemb
  11. I'm afraid I can't help at this stage without playing the tutorial myself - which I will do tonight - but intercepting the target and then ending up with a relative speed of 700m/s seem very high to me. And if the rest of it is 'on rails' and doesn't allow you to change anything then there must be a problems somewhere... Can you do a screen shot of the sort of rendezvous manoeuvre you're flying before you get your intercept? Wemb
  12. Bit less than 1.4 tons empty, I think - mostly built to shuttle science too and from low minmus orbit - but I way over did it in terms of the amount of mono I took with me. I'll have another play landng her on RCS tonight I think. Wemb
  13. Well - you're not going to be able to do much to a Hohmann transfer to make it more efficient (unless you're doing something that really isn't a Hohmann transfer) - my guess would be that if you're having to do an inclination change in LKO, that'll be taking up most of your fuel - that or your launch is very inefficient. Once you're in a circular, co-planar orbit, moving from it to the orbit of your target, and then matching velocities/orbit with it shouldn't really cost a lot of fuel at all. But inclination changes in low orbit are -very- expensive. Wemb
  14. Not sure - I can land on minmus in my 'grasshopper' light lander on RCS alone - but I can't get back into orbit, even with the normal fuel tanks empty. (One science Jnr, landercan, 4x round mono tanks, 4x RCS blocks and 3 oscar fuel tanks and a spark engine). You probably can, but it'd be tight. The limited thrust may be a bigger problem than dV. Wemb
  15. It does let you do some really sneaky things though - the idea of slapping one of these engines onto a rover solely to put it's centre of mass somewhere below the surface it's travelling on is very cool, if incredibly cheaty. Wemb
  16. Also right click onthe engine, see if there's a 'Test Component' option. Wemb
  17. Yup, the tourists ones are dull - but with that I just concentrated on building the most economical joy-ride vehicle I could, while I racked up the missions to pay for my science programme. It was a bit grindy, agreed. The surface survey ones are too boring for words. Wemb
  18. To also expand on X-SR71's advice, take a research lab out with you - it'll hugely expand the returns from science, but at the cost of time, and gives you opportunity to get practise rendezvous and docking, as well as planning for bigger, longer multi-ship missions to other systems. Wemb
  19. MechJeb will, if it cannot otherwise use main engines, attempt to perform manoeuvres using RCS thrusters (assuming the RCS system is enabled) - but otherwise, as above. Wemb
  20. Define 'lame'? It mostly, AFAIK, depends on what contracts you've already done (some are one-time only) and where you are on the tech tree. Wemb
  21. To be honest, I don't mind the having to go and collect the results myself aspect - but what'd really bugging me is not being able to selectively choose which sets of experimental data to collect and store in my Kerbal/Capsule - I've tons of science (over 40 sets of data) stuck in my orbital labs which I want to return to Kerbin, but can't because of one big one which will require 180 data storage points on the lab. I'd love to be able to pick out that one specifically to move it elsewhere so I can grab the rest and bring it home. Science awaits! Wemb
  22. Also, and this looks like an exploit even though it's not, this allows you to do multiple in-capsule crew reports by doing a crew report, EVAing, right clicking on the capulse, collecting the crew report, and then storing it again - turn the experiment result into scientific data - freeing the capsule up for more crew reports. Wemb
  23. There are also, sometimes, an alternate way to test - unless the contract says 'must be tested as part of the staging sequence' you can test components by right clicking on them in flight and selecting 'test'. Wemb
  24. Woot! - To get home, as other have said, watch what MJ does - but another way to think about it is this: You're okay at doing a Hohmann transfer to change between two circular orbits right? So, now imagine you're needing to do a similar transfer go travel from the orbit of the Mun to a Low Kerbal Orbit (even if don't intend to circularise when you're back at Kerbin) - you do it the same way - burn retrograde from your existing slow wide orbit to get into a smaller, faster orbit. The complication here is that you're orbiting both Kerbin and the Mun together - so you need to decide when, during your Mun orbit is the best time to leave to do the Hohmann transfer to Kerbin. As you want to burn retrograde (with respect to the Mun's orbit around Kerbin) your best time to departure would be (assuming you're orbitting the Mun counterclockwise) when you're coming back around the front of the Mun with you directly between the Mun and Kerbin which is when you're flying the opposite direction to that which the Mun is going around Kerbin. Get this sorted in your head and you're well on your way to working out how to do inter-planetary flight. Wemb
×
×
  • Create New...