Jump to content

UnusualAttitude

Members
  • Posts

    636
  • Joined

  • Last visited

Posts posted by UnusualAttitude

  1. Congratulations on your progress, Capi!

    What will you be using your pre-RAPIER career SSTO for? If it's for light cargo/satellite launch/crew transfer, then I'll second Wanderfound on the choice of twin turbos and either the LV-T45 or LV-T30. If you look at a typical spaceplane ascent, more than half of your fuel (LF and Ox) is used to boost out of the atmosphere into space. It is critical to have a high TWR during this phase (you won't reach terminal velocity in FAR) in order to get from 30 to 50k as quickly as possible and waste as little dV as possible to counter gravity and drag. Your aircraft becomes a rocket at this point.

    That's why RAPIERS are such a good deal in many cases: you get more closed cycle thrust from two RAPIERS for much less weight than a couple of jets combined with a traditional rocket engine. A few points of ISP won't make a big difference, and the RAPIER has a decent ISP anyway.

    If you want your spaceplane to go places/do things/carry stuff once it's in orbit, it boils down to having a high fuel fraction (so a low TWR on takeoff), and as much TWR as is reasonably possible once you go to rocketry, with the possible exception of spaceplanes with nukes, but ask Wander about those...:wink:

    If you're also interested in bigger spaceplanes, check my signature link for inspiration in designing something that will lift an orange tank or more to orbit. They are more complicated to build and I've been experiencing quite a few issues with FAR not liking some of the larger parts for some reason (excessive drag). Let me know if I can help.

    Salut, UA.

  2. Everything must go!!!

    As I’m sure you are aware, KSP 1.0 is almost upon us and the world is about to change for the FARia and Stock Aeronauts alike. This may be your last chance to try these rides before the laws of physics turn upside down, so don’t miss the chance…

    wSk72yd.png

    0lM3ad4.png

    The UA Industries range.

    Requires FAR (1.4.6 or 1.4.7): http://forum.kerbalspaceprogram.com/threads/20451-0-90-Ferram-Aerospace-Research-v0-14-7-4-2-15

    and Kerbal Joint Reinforcement: http://forum.kerbalspaceprogram.com/threads/55657-0-90-Kerbal-Joint-Reinforcement-v3-1-2-3-26-15

    All spaceplanes have action groups for engines, flaps, cargo bay and docking ports, solar panels, etc.

    A fuel balancer is recommended. (ex: http://forum.kerbalspaceprogram.com/threads/25823-0-25-TAC-Fuel-Balancer-v2-4-1-10Oct)

    So is the excellent Pilot Assistant (http://forum.kerbalspaceprogram.com/threads/100073-0-25-Pilot-Assistant-0-3-Nov-15-Altitude-and-heading-control-for-planes)

    ExAtmos SR/SRC

    For all your light cargo delta space plane needs, ExAtmos comes in two variants: the SR extended cargo bay model and the SRC crew cabin version. Both will carry a wide range of satellite and probes to a variety of orbits. Both are equipped for docking and orbital refueling.

    -SR mission examples:

    Circularize keostationary orbit.

    Satellite to Munar polar transfer orbit.

    -SRC mission examples:

    Crew transfer to Munar orbit.

    Land on Mun or Minmus if refuelled from LKO.

    Javascript is disabled. View full album

    download SR: https://www.dropbox.com/s/y5sbirczcywg5mw/ExAtmos%20SR.craft?dl=0

    downloadSRC: https://www.dropbox.com/s/xrg5e7acv8tfq7w/ExAtmos%20SRC.craft?dl=0

    ExAtmos LR

    The Queen of the Kerbin system and beyond, the LR version, apart from looking drop-dead awesome, can reach almost any orbit in the Kerbin system you care to imagine with a useful probe payload, passenger facilities and docking ability… Not that she will need it; with auxiliary tanks in her spacious cargo bay, ExAtmos LR is capable of an equatorial Mun landing direct, without refueling in LKO, and returning safely to KSC. Minmus is a walk in the park for this ship.

    Javascript is disabled. View full album

    download LR: https://www.dropbox.com/s/rfwv3300bdlv5lk/ExAtmos%20LR.craft?dl=0

    download LR max range: https://www.dropbox.com/s/u1ut5zxpi0o74p8/ExAtmos%20LR%20max%20range.craft?dl=0

    ExTract Heavy Cargo

    For all your heavy lifting requirements, ExTract will lift any payload you can fit inside her vast cargo bay to surprisingly high orbits. Orange tanks, entire station cores, space telescopes, you name it.

    Javascript is disabled. View full album

    download ExTract: https://www.dropbox.com/s/xygfk79g0xb6l1p/ExTract.craft?dl=0

    More to come, blue skies to you all.

    UA.

  3. A late entry... I had to put up with all sorts of problems with design, dV budget, weird FAR drag issues and awful frame rates. But it was worth every tedious second just for this awesome screen shot...

    a0vvxon.png

    No way near Wanderfound's design in terms of efficiency:

    -10,532 units of LF and 11,864 Ox.

    -10,561.12 funds for 52 passengers and crew.

    -203,1 funds per seat.

    ...but traveling in such style and comfort comes at a price, right?

    Javascript is disabled. View full album

    By the way, Wander: I don't know what deals QANTAS crew get, but even Ryan Air pilots don't have to pay for their own seats...just saying. :sticktongue:

    UA.

  4. SalehRam, you seem to have taken things to the opposite extreme in terms of rocketry... two LV-909s will not get your 24-tonne spaceplane to orbit.

    I suggest you keep the outer Rapiers instead of those turbojets: you'll still have more than enough jet power. Use the Rapiers in rocket mode to boost out of the atmosphere and use the more efficient 909s for circularization and orbital maneuvering.

    Yes, controlling an aircraft generally does get harder the higher you get. Looking at your craft I see it lacks reaction wheels (one is enough, but the torque provided by the cockpit alone may not be enough), and might not have enough fin area to keep it stable at high altitude.

    I would suggest adding a small Mk2 cargo bay behind the docking port to lengthen the craft and pull the CoM forward (then adjust the wing accordingly). It will improve the effectiveness of your tail fin and give you somewhere to put accessories such as reaction wheels, batteries, solar panels, maybe even a small payload or a science package. Remember to readjust your landing gear if you do this...

  5. A few ideas:

    -Keep the tailplane, but having it clip into the fuselage structure is probably a bad idea. Have you tried a T shaped tail (horizontal stabiliser at the top of the fin)? They're great for improving stability. Also, does that horizontal stabiliser have pitch control ? If not, you will be severely lacking pitch authority as your only control surfaces are close to your CoM. I'd say that's why you lost it...

    -Your engine torque looks reasonable. That shouldn't be a problem with SAS.

    -If you reached 45k then you're through the hard part. You should be able to just use hold prograde and push your apoapsis. Try it, it works.

    -you're nearly there, never give up !

    - - - Updated - - -[/CO

  6. I didn't find the lack of gimballing on the LV-T30 to be an issue with the design I posted above, and that's with a single reaction wheel and no RCS; she held straight even at full thrust.

    I still think it may be possible with a lighter design. If not, then it will be a choice between refueling in LKO (more efficient in the absolute) or having some fuel at your Munar station (less efficient but saving you real time by cutting out a rendez-vous).

    I'm looking in to your tourism challenge, Wander. The problem is that I don't have enough Kerbals available for recruitment. Do you just have to wait for more to come along? I will need a LOT, especially if there are failures...:sticktongue:

  7. That's very interesting, thanks Unusual :) I wonder if a pair of 909s would work better on the back end... slightly higher ISP and a tad lighter - but the low thrust might keep you in the atmosphere too long xD

    I'd reckon that if I can get to a 100x100 LKO, with 1600 dv, I'm pretty sure I can get to Mun (~850), tweak it (~50), circularise (~250), rendezvous (~100?), and return (250)... but there's no harm in sending a can of fuel with the station, just for a little extra if I come up short.

    The 4t cargo was a would-be-nice; I thought the crew cabin was also 4t, but apparently not!

    Well, that will teach me not to mouth-off on Wanderfound's thread... I came up a bit short on dV :(

    This was the best I could do...

    6E4ZXkJ.png

    I got to 100k LKO with 1,350m/s. It still has 100m/s for a careful rendez-vous and monopropellant for docking, it also has the crew cabin and I put a materials bay in there to simulate a science experiment, but lacks the 250m/s or so to get back.

    The good news is that that's only a hundred and something units of LF plus Ox per return trip to pack on your station.

    I'd forgotten how low the TWR is without Rapiers. Twin 909s won't work (but are a good combination with Rapiers for a small craft). Maybe you could try something with a Mk1 cockpit and the crew cabin (I just don't do Mk1 spaceplanes), and go to Mun from a lower parking orbit?

    Let me know how it goes.

    UA.

  8. Eddie, I would say it depends on the orbit of your Munar station. I have actually done quite a few lo-tech Munar orbits with twin turbos and the LV-T30 (more thrust, lighter), without refuelling, because I really am that bad at building/flying rockets...

    Getting a crew cabin and a light science package to a not-too-low equatorial orbit and back sounds possible to me. Getting four tonnes there sounds very, very hard. I don't have any Munar orbit pictures at hand but here is the sort of ship I used back in Tier 2 launching an ion probe (yeah, it ain't pretty I know).

    In all cases the dV budget will be rather tight.:wink:

    Ybt0oy5.png

  9. Wow, this is hard. I've spent a couple of evenings trying to get anything above 250 tonnes up there and have so far failed miserably. Too much flex in the wings, causing my designs to roll, flip or spin out even if FAR says green. Testing is also time-consuming when you can't time warp, as anything this big will take at least 15 minutes to get up to speed. Drag also seems to increase exponentially with size, making performance sluggish even with a good TWR. I suppose the twin KR-2L spaceplane shall not be... Taking a break and starting again from scratch if I have sudden inspiration.

    Any joy on scaling up, Wander or anyone else?

    Some interesting designs from the stock aeronauts... I would be curious to see more valid large Mk3 entries, just to see how you get around the structural problems...

  10. Nice...

    Here's my first entry, The Jug. It's a quick and dirty reconversion of my standard Mk3 cargo and got about two orange tanks worth to 75x75 km. 130-something parts.

    uSVO8zF.png

    It delivered:

    LF: 5,696

    O: 6,867

    LF corrected for O equivalent: 5,618

    Total fuel usage: 11,360/12,972

    Total cost in funds: 9,088/2,335 - 11,422

    12,485 for 11,422 funds or 0.915 funds per unit. Please check my maths.

    I'll be working on a dedicated tanker. So far, my fuel fraction is 0.68 and I think this can be improved with a Mk2/Mk3 hybrid or fuel tanks with a better fuel fraction than the spaceplane parts. The limit will probably be the thrust of the KR-2L engine if we are limited to 150 parts...

    Full flight:

    http://imgur.com/a/uOL2K

    Download:

    https://www.dropbox.com/s/cy1fha51k1ol051/TheJug.craft?dl=0

  11. Can't call this an unqualified successful flight, though - the plane broke right at 45k going 1900 m/s (wasn't looking at the Mach meter at the time). I was able to correct the spin and get the plane into the ugly ass orbit it's in in that screenie - but it took nearly every last drop of fuel I had to do it (including what was in the payload - TAC saves the day again).

    I find the "Hold Prograde" SAS feature usually counters any upper atmosphere instability perfectly well. Once your time-to-apoapsis is high enough (KER should tell you this, I suggest just under two minutes) switch on Hold Prograde and burn until you have your desired apoapsis.

    Unless you find that cheaty and want to fly it all by hand...:sticktongue:

  12. I've been having some real issues with this as well. No matter what design I build, I cannot cancel out the flex and bend. It only happens after I try taking off, and it with larger planes, it happens on its own. I've watched Scott Manley build a spaceplane from scratch, and he didn't really reinforce anything. I'm thinking it's something to do with KSP's joints. I think I've heard Manley mention a joint strengthening mod, so that's what I'm gonna try next. I was hoping to enjoy B9, but I'm just been continually frustrated with even simple designs.

    Hi Hafevil,

    If you having the same problems as the OP of this (very old) thread ie: wobble with FAR, in my experience it is more of an SAS problem than a structural one. SAS is constantly trying to over-correct. I would suggest you try a PID tuner, such as the one included in Pilot Assistant. Try reducing the different values until the wobble goes away.

    However I would certainly recommend Kerbal Joint Reinforcement also. I use it simply because my tired old Mac can't support the extra part-count of heavy strutting. With this, even my Mk3 designs don't require a single strut.

    Hope this helps you out.

    http://forum.kerbalspaceprogram.com/threads/100073-0-90-Pilot-Assistant-Atmospheric-piloting-aids-1-4-1-(Mar-11)

    http://forum.kerbalspaceprogram.com/threads/55657-0-90-Kerbal-Joint-Reinforcement-v3-1-1-1-15-15

  13. Hi,

    Is this what people mean by "telescopic" view from IVA...? I took these screenshots from a ship leaving Kerbin's SOI heading to Eve. The object I spotted cannot be Minmus, or anything else from the Kerbin system (as they would be behind the ship at this point). The nearest thing, judging from the map view (sorry, didn't take a screenshot) is Moho, but it seems to be too far from Kerbol to me. A mystery unknown easter egg planet, maybe ? :sticktongue: Sorry if this sounds silly, but I've just discovered this feature after reading this thread...

    Hc2AgC4.png

    3f5pbJ6.png

    TSbzDaR.png

  14. My latest design has a triple rudder - three Standard Canards - and is still experiencing issues with side-slip (either that or I've got a bigger issue - plane has a tendency to want to flip around and fly backwards once I get going good). I'll try swapping the middle one out with a wing piece tonight and let y'all know how that turns out - it was that same one I swapped out last night that crashed FAR.

    Yup, standard canards just won't cut it as tail fins unless it's a very small, light design.

    Also, bear in mind that the farther your fin is from the CoM, the more effective it will be at reducing sideslip. That's where mid-mounted swept wings (see Wanderfound's design) are superior to the tailess delta: the delta's centre of mass may be just too close to the fin for the latter to provide sufficient leverage.

    Solutions to improve delta wing yaw stability include dihedral (tilting up the wing tips) and winglets (a vertical wing section on the end of the wing).

    UA

  15. With all due respect to them, ignore the experts and get designing your spaceplanes if that is what you feel is fun. The only thing you need is the basic jet engine and some wings: aerial surveillance contracts will then provide you with plenty of cash and science to unlock the turbojet, and meanwhile allow you to perfect your airframe design and practice take offs and landings. Personally, I've never designed or launched a large rocket in KSP. All my "firsts" (Mun, Minmus) were with small landers launched by spaceplane. It's just what I like to do. Like anything in KSP, the learning curve is steep, but there is plenty of good help to be found on these forums. Just ask :wink:

×
×
  • Create New...