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Everything posted by AeroGav

  1. AeroGav

    Lower main stage thrust

    Ah sounds like you're making a Delta V Heavy / Falcon Heavy, with core stage throttleback. For the normal Falcon 9 full thrust, would using a Vector for the booster stage and a Terrier upper stage approximate the thrust and isp differences between the two stages, while keeping stage diameter constant ?
  2. I think it is easier to design a plane to be naturally stable, than it is to fight SAS for control. Use RCS build aid to make sure your engines are in line with centre of mass, so that the plane does not pitch up or down as engine power changes. Also use RCS build aid to make sure your centre of mass is the same with empty and full tanks. Be generous with vertical stabilizer area/and try to put as far behind centre of mass as possible - this gives it more "leverage". Dihedral/Roll stability is difficult. I only trim for pitch, and make manual roll inputs to keep the heading at 90 degrees East. In theory Dihedral should give roll stability, but i've never been able to make an airplane that flies to orbit without some manual corrections to level the wings. The problem with Dihedral on a conventional airplane layout is that it makes the wing sections act more like vertical stabilizer, but as the main wing is ahead of centre of mass, this can end up reducing your yaw stability. However, if you have a canard / delta configuration, perhaps you can put dihedral on the outboard and rearmost wing sections. This will cause the dihedral sections to be aft of CG and not reducing yaw stability. However, most unwanted rolling appears to come from bugs in the physics engine not aerodynamic reasons. For example, if you attach engine nacelles either side of the main fuselage and then attach wings to the nacelles, this can cause problems in some KSP versions, as can importing craft built on earlier versions of the game. Attaching the wings directly to the fuselage, or simply reattaching parts again without changing anything, or adding struts, can fix this.
  3. Are you flying with SAS on ? SAS conflicts with trim inputs, preventing the desired effect. It sounds like you already know how to fly an airplane with pitch trim, but i made a tutorial video last year showing the method. I don't turn SAS on till over 41km - and two seconds later the engines are shut down as we coast to Apoapsis. Make sure CC / Subtitles are enabled on Youtube so you can see the comments, I don't actually speak :-)
  4. Oxidizer, Schmoxidizer. Make Liquid Fuel only SSTOs and conserve that precious HTP for it's true purpose.. dyeing Kerbal hair blonde/pink/red. No good Jeb, that thing's too small for the peroxide crew.... THAT's better..
  5. AeroGav

    Ssto only using small engines

    On a winged ssto, this is incredibly easy because you don't need twr over 1. Even more so if jet engines are allowed. My KerbalX shares include a 1 Terrier, 4 juno ssto , and numerous panther/nerv liquid fuel only ssto. I have also built a Juno nerv winged ssto which worked, though wasn't particularly capable. Poodle is not a small engine. It is a beast ! I made this ugly career mode thing with a Poodle and 2 Panthers, lifted a Science Lab to orbit with gobs of fuel to spare I am not the master though. That title belongs to this guy - NERV from sea level to orbit, no jet engine or thruster of any other kind.
  6. AeroGav

    SSTO Liquid fuel only , no oxidizer. Does this only work for small SSTO? Well, this one is quite big actually. 6 Panther, 6 Rapier (air breathing mode only), 12 NERVs to keep the cabin warm. Bubble cockpit provides good view of the sky but not so good over the nose, parking may be difficult. .
  7. I think it's best to update the first post in the thread as I didn't read all the posts before starting something. I spent a couple of hours on it trying (once again) to come up with a satisfactory vertical launch spaceplane. No air breathing engines. The orbiter itself has a pilot and ten passenger seats. a NERV under each high mount wing. The main boosters have Reliant engines fed by a pair of FT800 tanks strapped to the sides of the NERV nacelles. The Reliant stage is not recoverable. It does not have the TWR for vertical launch however, so the first few seconds are assisted by a pair of Fleas. The Flea stage have parachutes on them and jettison so low that they can land before the airplane goes out of physics range. Won't save much money, bur it's something. The fleas boost us to an incredible 44 m/s and 160m altitude.. Reliant power for the masses. You can see the separatrons on the nose of the boosters. They yaw the nose outwards and downwards on separation, which causes aero forces acting on the body of the booster to push it further outward and down. The boosters get us to an altitude where the NERVs can work well, and through the sound barrier, but that's about all. It's not easy to build something out of multiple Big S wing parts that still looks ok. Dry wings would mean i need cylindrical tanks to store the fuel which would add drag however. Safety Features There is a ballistic recovery chute mounted to the upper fuselage. The abort button could be triggered to lower the landing gear, release the chute and fire the separators for all boosters. Between the recovery chute, ability of this craft to glide, low stall speed, landing gear , 40 m/s impact tolerance of crewed parts, and the crumple zone surrounding the crewed stuff, loss of all propulsion should be fine whether it happens 3 seconds , 30 seconds or 3 minutes into flight. There is an inline clamp o tron ahead of the cockpit, which can be used to transfer crew to another vessel should the orbiter have a fault that prevents safe re-entry. However it is not outfitted with an RCS system which precludes routine use. The orbiter would simply rendezvous with the rescue vessel and passively allow a full translation space tug dock to it. Design Issues, work in progress I really hate seeing wings go unused during the ascent, such a waste of mass ! In this vessel's case, the lift to drag ratio they have enables it to fly to orbit with a TWR under 0.5 , so long as the booster gets it to 400 m/s and 8km altitude. In turn, the low TWR requirement means we can use hyper efficient NERV engines, and put most of our fuel in the wings. The biggest issue is that the orbiter stage, under nerv power, flies at a 5 degree angle of attack with the nose about 7 degrees above the horizon, for perhaps a 2 degree climbing angle. The booster prefers a 30 degree climb angle and of course launch with the fleas is vertical with TWR > 1. Fairly aggressive maneuvering is required. Below 100 m/s in the booster phase it wants to lawn dart so full back stick, then it starts wanting to pitch up more and more due to the lift , and towards the end of the booster phase you need to start flattening out the climb angle to something more suited to flight on NERV power so you're banging the stick forward. The wing is mounted high on the fuselage to make room for the boosters, which means most of our fuel is above CoM. Causing a pitch up effect from the NERVs. If you climb at too steep an angle, you'll get into a low dynamic pressure regime (high and slow) and this becomes quite noticeable. If you climb more shallow aero forces surpress that tendency. When circularising it can really pitch up a lot if you bang the throttle open abruptly. Flight tips As I say, key is to not let it lawn dart after launch (pull up), then nose down as needed to keep climb to no more than 30 degrees. Above 7km start to push the nose down to a shallower climb (10-15 degrees). Once on NERV power, try to take SAS off and keep it off as long as you can to minimise drag. It is aerodynamically very stable but the torque from the engines likes to push the nose up a bit. Use pitch trim to maintain climb angle - ALT + S key. To begin with, you'll be halfway up the pitch trim scale to get a 5 degree AoA, as you get into the upper atmosphere, you'll be winding this off as torque from engines is pushing the nose up plenty all by themselves.
  8. As you don't drive, the thing you might not realize is that even normal driving, within speed limits, obeying the laws of the road, keeping under 0.5g or whatever, is fascinating. It is more complex than any video game, so much stuff going on, so many cars and junctions to keep track of, gear changing, rev matching, an infinite map to explore. If you really want to experiment with stuff that falls outside of those limits, have a track day, take an advanced driving course, go go-kart racing, or just play GTA V There are far more paranoia inducing things than insurance black boxes these days. Automatic number plate recognition cameras everywhere, any day you could get a "penalty charge" notice in the post, because you exceeded the speed limit by 1mph or had 1 wheel in a bus lane for 1 second at 2 am when driving along an unfamiliar, poorly signposted road. "Crash for Cash" fraud. Every time you take your car in for its annual safety inspection and the garage tells you it needs an expensive repair to X, do you trust them ? Etc.
  9. UK has a lower accident rate than just about any other country in the world - it's safer to be a driver here than in US, Germany etc by a factor of two or more. However, the accident rate among young male drivers has been slow to fall, despite introducing a large theory component to the driving test with "hazard perception" test videos. However, I read the real problem with young male drivers was once they got their mates in the car with them ... one up, they were fairly safe. There was suggestions of banning new drivers from carrying other young people as passengers. However, I heard that these "telematics" black boxes, that spy on your driving and report G forces and speeds to your insurance company in real time, have had a dramatic effect on these young drivers (they've had less effect on older ones) What I suspect is happening, is that it allows the driver to resist peer group pressure to do stunts when his mates are in the car. In my day, refusing to do any of that stuff would have them thinking you are too boring, too chicken, or too unskilled to try a bit of racing or drifting. Young people understand money however, they don't have enough of it and they want to spend it on clothes, music and beer. You can just point to the black box and say "rather spend my money on beer, sorry" and your friends will get that. One reason I heard for UK's high insurance premiums is due to the way injury compensation for passengers of vehicles in a collision is paid by the insurance company. In the USA I think the medical insurance system or state ends up picking up the tab.
  10. It's a mystery to me how in the UK, (similar to Poland, I expect) young drivers are regarded as a menace, if you're under 27 you'll be paying over £2000 a year for insurance on a 10 year old car with 65HP. I took my driving test at 17 but couldn't afford a car or the insurance till i was 27. Yet in America, you can drive a small block Chevy at 16 with God knows how much HP .. how are the roads not littered with dead teenagers? When I was at college, no-one had a car, for these reasons. Then, one of my classmates was able to borrow his Dad's car for the day... no-one the class ever gets to ride in a car that doesn't have their Parents in it.. so immediately all the other lads jump into the passenger seats and start asking him to do stunts... Wheelspin ! Handbrake turns ! I suppose the reason insurance companies try to price young drivers off the road is because sometimes these stunts go wrong. What if he does a handbrake turn, hits a curb and rolls the car ? No-one was wearing a seatbelt... now 4 teenagers will have disabilities for the rest of their lives.. the driver's insurer has to pay out millions in compensation. Back to the overtaking question... In the UK single lane roads have speed limits of 50 or 60mph. The motorway speed limit is 70mph. Honestly, I don't like going 10-15mph faster than the car i am overtaking anyway. If I need that much speed, the gap must have been too small. Before I overtook, my view of the road in front of the slow car was obstructed by it, if you accelerate to 90mph to go past a car doing 50mph, you might suddenly discover a hazard in front of that slow car once you're past him and now you are going too quick to stop. I'm surprised your medical condition is an obstacle to driving. I've known ADHD sufferers who drive. In the UK, so long as you pass the theory test and practical test, and aren't on medication that affects your driving, you would get a licence. The theory test is quite tough now though, there is a hazard perception test, where they show video footage from a car and you have to press a button to identify the risky situations. Like i say though, over here getting the licence is the easy bit...
  11. When I was younger I had a job delivering Pizza on mopeds that were restricted to 30 mph. Also when I was young, I drove a lot of very underpowered cars (could not afford anything better, could not get insurance for anything better, parents would not trust me with their powerful car). I think so long as you know what the car will do, you can make a safe decision about whether to overtake or not. The closest I came to an accident was when overtaking in this turbo diesel car which would accelerate very strongly at first, then the power would rapidly tail off above 2500rpm - you'd start the manoeuvre thinking you'd do it easily, then the power would die off just as you were too far into the overtake to abort. Eventually I got to know the car and to simply not attempt overtakes on single lane roads with a speed limit over 40 mph. I suppose you don't want your auto speed limiter suddenly reducing your car's top speed mid overtake because it thinks you've moved from a 70mph zone to a 50 limit. Still, I don't think accident statistics back up the idea that "power is a safety feature, it lets you overtake more safely", it just makes people take even more risks. If we're honest, the real reason we like power is because it's fun. I'd be happy with a hard 75mph limit, provided the car had some kind of "Head Up Display" (HUD) tech to visualise how much room you need to complete an overtake based on the speed of the car in front and whatever the limiter is set to, so you can decide whether to overtake or just chill.
  12. AeroGav

    Λ uɹnʇɐS

    I always wondered how they got back from the moon after putting their flag on it
  13. AeroGav

    Post your LANDERS here!

    1.6 broke my KSP but after deleting the folder and re-downloading I am in business again. So, here is the maiden voyage of my Fireball XL5 replica - My name isn't Azimech so I didn't give it a full launch ramp, I just slummed it with a pair of Thumpers stuck on the bottom with the landing gear, that are jettisoned after horizontal takeoff. One Whiplash, and six Junos clustered around it. Non airbreathing propulsion is handled by a single NERV (clipped into the Whiplash) and the four Sparks you can see out on the wingtips. The fwd oxidizer tanks are mostly left empty. It's not exactly blessed with thrust but there is decent delta V left over, which befits an interplanetary ship if not the name. I didn't bother with the separating thing - that would probably add too much drag for the weak engines to overcome.
  14. Given the runaway success of the Kerbal Express Airlines thread, I've decided to create its space going, space tourist counterpart here. The idea is to submit your space tourist vessels for review, and the entries can be collated and grouped according to their tech requirements, cost , and capabilities. Peer Review The other thread suffers from a shortfall of reviewers, so the first rule of this challenge is that to qualify you must have reviewed at least one other person's vessel before submitting a craft of your own for consideration. It is acceptable to submit multiple vessels for HiJinks Inc., so long as the number of craft you have reviewed yourself is equal or greater than the number of craft you submitted. This should stop the thread falling behind. A craft can be reviewed multiple times by different persons (all the reviews will be linked, and ratings averaged). If you want to review a craft but have no intention of submitting a vessel of your own, that's fine too, you're helping the reviewers keep up ! Vessel Type All kinds of tourist vessel are considered. I suggest however, categorising them into three main types : Spaceplanes require basic airplane flying proficiency. If you have zero proficiency with this type, and have never made a successful flight in a KSP aircraft (including stock ones) then you might not be the best person to review such a vessel... but everyone has a first time, right? Rockets require basic vertical launch skills, such as the ability to perform a gravity turn and ballistic re-entry. Shuttles launch vertically and later transition to horizontal flight, so require both airplane and rocket skills to fly. Re-Usability SSTO and partially/fully expendable craft are being considered by HiJinks. For vessels with expendable elements, the operating cost per tourist seat is calculated by adding up the cost of parts that are left to crash into the sea, and dividing by the number of tourist seats the vessel provides. Because fuels have an unrealistically high % of launch price in ksp, the cost of fuelled parts discarded is taken from the tank in its empty state. Capability Broadly, this is categorised as follows :- LKO - can bring tourists to an orbit with AP and PE below 400km Mid Orbit - Can manage an orbit with both AP and PE above 400km, so well able to rendezvous with a Kerbin station at fairly high orbit. Flyby - Can manage a flyby encounter with Mun or Minmus Other body - please specify which it can reach, and whether this refers to orbit, atmospheric or surface return capability. Tech Tier What is the tier of the highest tech part in your vessel ? Runway/Launchpad Tier How far do you need to upgrade the facility to launch this? In career mode, Tier 3 is not cheap! VAB / SPH Tier As above ! Review Guidelines When reviewing another person's vessel, please include the following ratings : Death Trap Rating One Skull Stable in all phases of flight, not prone to breakup or heatsploding unless grossly mishandled Two Skulls Can go out of control, overheat, or break up in certain parts of the flight, but possible to operate safely with a trained crew. Three Skullls Requires significant skill or luck to return in one piece. Truly Kerbal stuff. Ease of Use IOW, how easy is it to obtain the advertised capability ? Three Stars The vessel does not require precise piloting to obtain desired performance or is so stable that precise piloting is easy to do. Two Stars Takes a few goes to get it right, but was eventually able to get it there. Three Stars Hard or impossible Time to orbit How many minutes elapse between engine start and cut off (coasting to AP) when flying to orbit ? (if you can remember!) This is a category rockets are probably going to excel in ! I'm going to be busy for the next 4 days, but after that i'll be around to admin this ! Good luck all and hopefully HighJinks Inc. will soon have a wide variety of vessels to choose from !
  15. AeroGav

    Post your LANDERS here!

    Never saw the show but the theme song's cool :-) Wrong thread for it I guess, but I think I could make an SSTO XL-5. Small engines a mix of Junos and Sparks, a center Whiplash, and I'll have to figure a place for a NERV or two or three. Was going to use Big S main wings, and big S strake orientated vertically on the wing tips instead of cockpits like you used. Hope the CoM works out ok.... the takeoff looks scary too... not building a ramp like it used in the show... perhaps a dolly with some Solids to push it off the ground?
  16. AeroGav

    Post your LANDERS here!

    I 've been binge watching Space 1999 season 1, tried to imitate the eagle transporter : I should stick to Spaceplanes perhaps. It has one NERV on the back. The lift engines are a terrier at the front and 3 sparks to the rear. The lift engines are toggled with RCS action group, when landing burn retrograde and toggle lift engines to keep descent rate and deck angle reasonable. It is well balanced at least, CoM is smack bang amidships with no shift as fuel is used, little or no torque from use of engines. Just about enough lift engine fuel for landing and plenty nerv delta V for LKO -> Munar ops.
  17. ...and one more.. Tech Tier 7 Runway, R&D and SPH all required at Tier 2 Class SSTO Spaceplane Capability 1 pilot and 2 tourists, Mid Orbit Flight Profile Action group Abort toggles nukes The wings are angle up to make lift even when the fuselage is on prograde hold, keeping the nose down so it doesn't climb too quickly can be a challenge on jet power. Best to go supersonic between 4 and 8km up , can use Abort action group for a boost from Nukes if needed. Once sonic, try to stay below 14km until over 750 m/s, if it shoots over that in a climb, just let it come back down naturally. Once over 750km , then stage the nukes in . At this point, go on prograde hold and keep navball in surface mode, let aerodynamics take care of pitch angle.
  18. Here's a craft of mine to get this started Tech Tier 7 Runway, R&D and SPH all required at Tier 2 Class Partially reusable Spaceplane Cost 3575 Kredits per tourist per flight Capability 1 pilot and 2 tourists, capable of reaching Duna, flying around in the atmosphere for a bit, then returning to Kerbin. Landing gear too fragile, so touchdown on Duna itself not recommended. Flight Profile Action group Abort toggles nukes The wings are angle up to make lift even when the fuselage is on prograde hold, keeping the nose down so it doesn't climb too quickly can be a challenge on jet power. Best to go supersonic between 4 and 8km up , can use Abort action group for a boost from Nukes if needed. Once sonic, try to stay below 14km until over 750 m/s, if it shoots over that in a climb, just let it come back down naturally. Once over 750km , then stage the nukes in . At this point, go on prograde hold and keep navball in surface mode, let aerodynamics take care of pitch angle. When the fuel tanks in nuke nacelles run out (usually happens within 10-15 seconds of jet engines flaming out) stage for the third and final time to jettison these motors. Flight envelope (left is jet power, middle is jets and nukes (stage 2) , third is final stage, jets jettisoned)
  19. AeroGav

    Impossible Parts Ideas

    The way I'm reading this is practical joke type parts rather than OP ones, stuff that makes you sound like an idiot when you ask for one. Solid Fuel Line (so you can asparagus stage your SRBs) Zero point wings (generate lift from the quantum particles that spawn in the vacuum of space. Don't work in an atmosphere, but allow your space vessel to make banking turns. As a side effect, produces "swoosh" noises and a slight bobbing motion in flight, as if your craft is actually suspended on a piece of string) Space Turbine (very low mass part that produces a continuous engine sound and plume to keep the crew happy while coasting. Occasionally breaks down causing orbit to rapidly decay).
  20. AeroGav

    What did you do in KSP today?

    Reduced frequency of vomiting is worth almost any price. Sign me up.
  21. AeroGav

    Cool Spaceplane ideas

    With Kerbal aerodynamics, it is possible to make a conventional ssto (no lift engines) takeoff and land in its own length, so i've never felt the need to put something like that together. There would be a mass/drag penalty for the lift engines or engine swivelling pivot which i think is greater than that a STOL conventional plane would have. After doing this, it flew to Minmus.. And this one landed on the VAB roof helipad, took off again and could have gone to Duna.. Now that said, when there is no atmosphere and gravity is less, VTOL makes sense. I've been watching Season 1 of Space 1999 this week, and I really want to make an Eagle Transporter now, they look like they were based on this real Munar transport concept (though the RL design had bigger propellant tanks and only had the delta V for surface->LLO ops. Eagle Transporters, Barbra Bain, Ziona Morton, this show had so much hotness...
  22. AeroGav

    What did you do in KSP today?

    One thing that really drives me potty about this game is minor updates breaking your craft, mods that add parts just seem to make the picture even worse.
  23. AeroGav

    What did you do in KSP today?

    i didn't mention, but I have a MM patch to add fuel to the wings which gave me the extra range. I also use mod FTMN-80 NERVs which are a little lighter & higher thrust. I could probably drop the radiators, but 1.4.5 it didn't hurt too bad. Nothing else is on the sides, the solar is mounted in the service bay just like you described. I did get around to checking stock parts 1.5.1 vs 1.4.5, in the SPH the dV readout is about the same. I haven't tried a stock test flight in either yet though. The SPH delta V readout only takes account engine ISP and what % of your mass is fuel, put a Wheesly on the first stage if you really want to see some crazy numbers :-) I'd deffo get rid of the rads, i can only think drag losses are what's killing you. If you want lower temps on ascent and re-entry, add wing area, the extra lift means for any given airspeed, you will be at higher altitude so heat will be less. Drag from fuselage parts (which is the major source of drag in stock aero) will be lower for the same reason, so it is easier to fly on a lower TWR. Oh and you have wet wings? More fuel available too. Always chose wet wings over cylindrical tanks where you can (weight and balance, trim issues force your hand sometimes). Dry mass is not such a big deal with 6 tons of NERVs to lug around, a few extra wing parts gets lost in that. It's all about how much fuel you can bring without drag overwhelming your little nerv motors.
  24. AeroGav

    Cool Spaceplane ideas

    For partial re-usable designs, I am a big fan of detachable (jet engine) pods, I've built quite a few that way. The Space Shuttle Way, which your ideas are mostly variants of, I've never produced a satisfactory solution. Aerodynamics is my thing and dealing with off axis thrust/space plane on a stick launches (Centre of lift at the FRONT ?!) is way beyond my vertical launch expertise - the few rockets i build are nice straightforward symmetrical things and even then they mostly crash. Example of a low tech, tier 7 Pather/NERV 2 stage space plane is this - Despite having only Panther jet engines and NERV rocket engines, it manages 4000dv in low orbit. The panthers - with their intakes and fuel tanks - are right on the plane's centre of mass so when you punch them off, the airplane doesn't even twitch. Because they don't have to lift or fight the drag of these nacelles any more, then 3 nervs can haul this thing on to space without too much in the way of gravity loss despite the large fuel fraction. If you wanted to kick this up a notch, with more tech available 1. wet wings would make a BIG difference. Lift takes care of not falling down, when your velocity has not yet exceeded orbital (2200 m/s). The problem for these weak and heavy, but fuel efficient NERV engines, is drag. Unlike real life, the vast majority of drag in KSP comes from fuselage parts and cylindrical tanks in particular. Big S wing strakes have a much better capacity to drag ratio than any other tank part. So a wet wing Kranker i'd get rid of all the mk1 tanks i can (except for any i need for trim/balance) and get the rest of the capacity i require by spamming big S wing strakes. 2. Swap the Panthers for Whiplash. Panthers max out at 750 - 800, Whiplash give good power out to 1100-1200. They are heavier (1.8 vs 1.2 ton) but you're dropping them anyway , so who cares. And they are barely any more expensive. Rapiers have an even better top end, but cost 3x a Whiplash, not sure you can justify ditching those in the drink. 3. The main issue is that the airbreathing part of the flight simply doesn't use all that much fuel, so there isn't all that much empty tankage to stage off. You could perhaps replace several some 3 ton NERVs with a single 1 ton Aerospike, and have a bit of LFO tankage on the jet nacelles. This will reduce your dry mass once the empty LFO is gone. The LFO tanks will add a lot of aerodynamic drag, but once they're staged off, you're no longer paying that penalty, and you'll be doing a high percentage of orbital velocity, meaning the wings will not have much gravity left to fight, and will pull you way up into the atmosphere where drag is minimal, and the reduced number of NERVs can finish the job. Hmm, perhaps I should build this Kranker II airplane sometime....
  25. AeroGav

    What did you do in KSP today?

    Nice looking ship, a mixture of some variable geometry fighter bomber and executive jet. I haven't played in a couple of weeks but the 1.5 patch seriously messed with mk2 designs in particular and i also encountered a major issue with how drag is calculated on mk2 cargo bays. It looks like you are using only mk1 parts in this and haven't got any bicouplers on there. so should be good. If you kept to more or less the same fuselage as the example design in the tutorial thread, that ship has about a 30% fuel mass fraction and never could get beyond mid orbit - it simply didn't have all that much fuel - given that Panther engines can only take you to 1/3 of orbital velocity, much of that is used just reaching low orbit. I didn't bother adding more tanks because the goal was to show a simple design that steered the middle ground between running out of fuel before reaching orbit (fuel fraction too low) or being sluggish and hard to fly (fuel fraction too high). It has plenty of fuel to reach low orbit but just falls short - about 100m/s - of being able to do a Munar flyby. So, unless you added extra tanks, i don't see how you'd escape Kerbin SOI on that. I've just noticed there appear to be extra things stuck on the airplane though. Is that an airbrake atop the main fuselage ? Fair enough, it won't add much drag when stowed. However, on top of the nerv nacelles there appear to be radiators? They add a lot of drag, but don't actually cool you down below 70km. I suspect you've now got so much drag it fails to accelerate on the thrust of two nervs (120kn total). What else is stuck on the sides? Bear in mind solar panels add a lot of drag too, the deployable ones are protected from damage by the atmosphere when stowed, but they still make a lot of drag (more than the cockpit, if i recall) which is why i mount them radially on a small battery or reaction wheel in the service bay.