Kryten 2X4B 523P

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About Kryten 2X4B 523P

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  • Interests - my retro remake games site - my kerbal blog

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  1. Youre using wheels spaced like youd have on a car, for weight distribution. The rear wheels are way behind the COM, which will stop the nose lifting when you pitch up. That plane is light enough though that you dont actually need 4 wheels, you can use 3. Think of the COM as a pivot point or axle - to pitch up off the runway the plane will need to rotate around this point, but it cant because the rear wheels are so far back it prevents this. For the nose to come up, the tail must go down, and it cant because the rear wheels are there keeping it planted on the runway. The rear wheels need to be much close to the COM, as a guide try between the COM and COL indicators and adjust the heights as Scarecrow indicated. Steering would also be more difficult on the ground because those wheels are not steerable. Alternatively, you could try putting the wheels in taildragger configuration. Put a single, small steerable wheel at the end of the tail assembly (the LY05), and move the front wheels back a bit nearer the COM (but in front of it still). This will also give you that nose up angle you want to start with on the runway. Remember to rotate the wheels dead straight using absolute mode (F key when using the rotate tool) to help prevent veering on takeoff.
  2. Heh :-) As you probably know, control authority is all about how far the surfaces are from the COM vs how heavy the plane is - basic leverage principles. As its pitching from the tail, thats a lot of leverage given those winglets used for horizontal stabilisers. Likewise for the roll control on the elevons. But yeah, a different tail set up using just the elevons for control wouldnt need as much adjustment. 70 ms was the point I noticed it was in the air, took me by surprise actually! The actual take off speed is probably a little less, and yeah, the difference is most likely due to the extra lift you have with the bigger wings. If memory serves, you need about 1 lift per ton on the main wings for light aircraft (might be a little more, dont have my spreadsheet handy). That plane is about 4 tons, so ideally 4 lift total. Those swept wings have about 1.4 lift each (again memory), so thats 2.8 lift, a little on the low side - so it has to go faster to generate max lift to get in the air. Be interesting to see some pics of your plane.
  3. looking at that, wheel layout is probably your biggest issue, as the rear wheels are way behind the COM. However, Id make the following changes: If youre intent on having the landing gear in tricycle formation (small wheel at front, two behind, move the rear wheels so theyre roughly in line between where the COL and COM are in your screenshot, and move them up the fuselage a bit so that the nose sits pointing upwards slightly on the runway. Personally, Id turn it into a taildragger with a small, steerable wheel on the underside end of the tail connector, and two LY-01 just in front of the COM (basically right where the cockpit meets the fuselage. This will give most of that "nose up" stance you want from the start. Remember to rotate both sets of wheels straight using absolute mode (f) Move the tail fins right to the end of the tail connector. Move the horizontal ones down a little so theyre off the midline. Move the engines down until theyre on the midline - where they are at the moment will be pushing the nose down. Rotate the main wings forward a little, which should bring the COL back forwards. Rotate the wings upwards a notch to form a shallow V shape viewed from the front of the plane. Set the control surfaces as follows, if you havent already - Elevons on the wings to roll only, vertical tail fin to yaw only, and horizontal tail fins to pitch only. drop the authority limiter on each down to about 20 to start with. That should come pretty close to sorting your issues I think. Edit: After having a bit of a play / recreate it should look like the following screenshots with the above changes - note it will still need control input to get off the runway. However, if you change the landing gear as well to a taildragger like so, itll take off with no control input at about 70 m/s
  4. I built a microlight!
  5. ok, where to start.. Tail - rotate the tail fins so that theyre level. This is probably the source of the lift arrow pointing the wrong way. Move the tail fins and rudder backwards to the end of the tail connector. Rear Wheels - ditch both, theyre unsteerable. Replace with a single, small steerable wheel which will turn the plan into whats called a "taildragger" - 2 wheels at the front, one at the rear. It will steer from the back then. Front wheels - rotate them in absolute mode until theyre straight in all axes, and move them back a bit so theyre closer to the Centre of Mass (COM) Wings - these wings are a bit of a pain to use actually - use the rotate tool so theyre not swept back as much - this will move the Centre of Lift (COL) closer to the COM, but you still want it to be behind the COM a bit. Finally give the wings a little upward rotate so the wing tips are higher than their connection to the fuselage. This will give you some clearance for take off & landing. Holding shift while rotating will let you move in smaller increments. Engines - mount these on the tail connector and rotate them straight, and move them so theyre just below the COM line - this will make sure the thrust isnt blocked by the tail Control surfaces - remember to set the control authority for each control surface - for a light plane like this you want the wing surfaces to be set to roll only, on the tail the rudder should be yaw only and the tail should be pitch only. Drop the authority level to about 50 to start, you may want it lower. And you should end up with something like this - which doesnt fly too badly actually: Front: Side with COM / COL / COT
  6. Havent had much time or incliination to play much lately, far too much going on in my life atm. However, had a little time today and came up with this - weighs in at a shade over 1T, and will take off at 30m/s with control input, 60m/s ish without. Juno is thrust limited to 40%.
  7. Figured Id have a go at this - concept being a shuttle with recoverable / flyback boosters. Managed a 12T payload. Pics from test flight.. On the pad : In Flight Orbit! Flyback Booster Seperation Made it back! Booster made it too (only recovered one on this flight test) - capable of landing in both water and terrain.
  8. The causes of a plane yawing / veering on the runway are many and varied, and these are the ones Ive come across myself. In no particular order: Wheel misalignment in VAB (align them using rotation in absolute mode) Wheel misalignment when mounted on wings caused by wing flex (wheels "splay out" - try autostrutting wings in VAB) Wheelbarrowing or unicycling (rear wheels / body lifts before the nose - COL / COM issues) Fuselage flex. Asymmetric thrust (rare one, found once or twice on bugged craft, but worth checking thrust isnt blocked either) No of wheels vs mass of craft. If the craft is too heavy for the wheels youre using, it can cause veering. Try adding a couple more around the COM / COL pivot point. For example, ideal weight for the lowest gear is around 5 to 6 tons, more than they they stress / explode / veer. Adding more landing gear spreads the mass, reduces the wheel stress. I suspect that each landing gear has an ideal mass range associated with it.
  9. Playing about with a "back to basics" approach, so heres an Apollo mission style lander - or MEM (Munar Excursion Module). Its a 2 stage lander (one for decent, one for ascent), some science experiments and has just enough fuel to land, return and rendezvous from a 20km orbit.
  10. Further development of my Javelin - not so much an SSTO now, more an SSTAA (Single Stage to Almost Anywhere) Swapped out one of the passenger cab (so only 16 kerb-pacity), added some more LF, small convertotron, drill, small ore tanks, rads, comms and some solar panels. Hit 81km orbit with 31m/s left on the closed cycle rapiers, switch to nukes for 3350 m/s. Enough to get to Minmus, land, takeoff (without mining), head for kerbin, circularise (no aerobrake needed), de-orbit and land. A bit more tweaking and I might get a SSTA out of her. Here she is sitting on the surface of Minmus (although landing was a tad hairy...)
  11. Been continuing with my Javelin SSTO series, working on a passenger variant that is capable of making it to the moon and back. Could probably make it to Minmus as well. Ended up with this. 32 Kerbal capacity. Makes a 85km circular on Rapiers only (with bingo fuel), then switch to nukes for the rest of the ops (with 2700 m/s in the tanks). Burn times out of LKO are a bit long at only 0.31 TWR, but can rendezous with a station in mun orbit at 25km, then make it back and survive an aerobrake pass at 30km, landing on the second pass. Good for water landings, runway and fairly flat terrain.
  12. Pretty much final (only need to add some RCS and do a little more tweaking) version of my Javelin Mk 1 SSTO. A little smaller and lighter than the prototype (168T loaded vs 189T loaded, and 8 rapiers vs 12), can still loft a Big Orange (36T) to 80km, leaving 550m/s in the tanks (loaded) and 950m/s once the payload has been delivered. Take off & flight is a doddle - just point it at 10 degrees off the runway and leave it there until 10km, drop the nose slightly to 20km, then engage closed cycle and ride up at 20 degrees / coast / circularise. Landing - even easier - almost completely hands off, and has a great glide slope. Can even land in water safely (and take off again without cargo, not tried with cargo yet). Initial tests of a heavy version show it will lift 2 Big Oranges to the same orbit, with 400 m/s left in the tanks. Here she is in re-entry.
  13. Had a bit of a hiatus (personal stuff), but started dabbling again recently in sandbox. First attempt at building a Mk 3 based SSTO capable of taking a Big Orange to 80km by scaling up the calculations off my earlier successful SSTOs. And -- it works! Manages to get to 80km with 770 dv left in the tanks, and is pretty easy to fly. Still need to add some ancillary systems, but pretty happy with this prototype so far.
  14. Yeah., shocking I know :-)
  15. Im nowhere near Rune's level at dealing with spaceplanes, but Im at the point where theyre usable to launch sats / interplanetary probes for nearer bodies, or crew transfer / recovery. As Rune has said, its all about ratios, as I found with trial and error. If you really want to go through the process, start with a single rapier powered craft, keep it minimal and when youre successful, work out the ratios of lift / mass & fuel per rapier, and go from there. My latest career isnt at that level yet, but when I tested this design in 1.2 pre, it performed even better than in 1.1.3