AeroGav

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  1. I ended up overshooting and climbing too high on my initial burn, reaching an AP of 65km at 1900 m/s - this thing makes a lot of lift ! So i cut the engines and let it coast down on prograde. Restarted engines at 50km, things start getting hot below 40km, end up pulling several Gs from lift at 37km to level off. Overheat bars are shrinking again so i start pitching down, trying to delay my broaching 50km as long as i could. If going above 70km before the record attempt is against the spirit of the challenge, i feel like i could use some high thrust LFO engine for the final fling, when its no longer possible to stop the ship climbing and you just want to get as much velocity as you can before you bust 50k
  2. I don't have time tonight to design anything specifically for the challenge, but I wanted to see what a recent airplane of mine would do. I give you the Korten Fledermaus flying wing - https://kerbalx.com/AeroGav/korten-fledermaus Still had plenty of fuel left but those Type B nose cones like to melt. They are fairly important, they keep the NERVs attached to the wing. Doesn't accelerate much once these pop.
  3. I don't think you're the first person to say my designs take too long to reach orbit, so i had a go at making a more powerful version. I must admit, I really like cruising through the upper atmosphere, because it's the only time you get to see it (too high for airplanes, too low for satellites) so that's why i build them like i do. I have a savegame from the point where my spaceplane is ready to stage in the NERV engines so i can skip straight to this part of the flight. Having reached orbit with as much delta V as possible, i then usually revert or just leave the guys floating up there forever, and go design another spaceplane. Even though i got the delta V to go some place, i don't particularly enjoy that part of the game - plotting manuver nodes and waiting around. Anyway, instead of trying to do it with as little as possible (one Whiplash, two LVN), this has twice as many jet engines and one extra LV-N. On my first attempt I got to MECO in ten minutes, second time i screwed up and climbed too steep, had to dive down again for the speedrun , which is why the screenshot shows MECO at 11 minutes. That's about half the time of the original design. Although the launch mass is higher due to the extra engines, it doesn't use much, or any, more fuel to get into orbit. Once again, this is a RETROGRADE orbit. Going East West like a sane person would leave a lot more delta v, save time and not get so hot. https://kerbalx.com/AeroGav/Snoopy-SSTO In terms of the NERV or not to NERV debate, I agree that at this particular tech level it makes less sense especially if you're only going to low orbit in an east-west direction. NERVs really shine when you're doing Panther / NERV because the top speed of the Panther is low and the rocket mode burn to get to orbit is a long one. This tech level is important i think because whilst NERV take a few science points, they can be done on a level 2 R&D building, whereas the Whiplash/Aerospike node is tier 8 and needs the Max level R&D. Getting the cash for that upgrade is the longest grind in career mode ! Paradoxically, NERVs also work well at higher tech level when you've got BIg S wings to hold all your fuel in. This gives a liquid fuel only design a big advantage in drag reduction over something that needs large LFO tanks. For example, check out my flying wing - https://kerbalx.com/AeroGav/korten-fledermaus I think this is more your kind of ship MK, about 7 minutes to MECO - still plenty of Delta V left too !
  4. Trouble is if mass goes up, you get more downforce via gravity but surely the amount of force needed to get it moving, make it stop and make it turn go up by just as much ? Though of course i'm assuming kerbal physics work like real physics which is a big if ! THe OP's video just looks like those small rovemate tyres are made of wood. Either that he's gone into friction override and set all four wheels to zero. (Maybe the low weight confuses the Auto friction control preset) turn the back wheels to max friction and give the fronts a lower value, see how that goes.
  5. I did win a payload mass fraction challenge with a nuclear engine, liquid fuel only ship. However the things you have to optimise in a nuclear ssto are completely different to a high twr rocket one . The nuclear ssto has a much lower fuel fraction , needs high lift and low drag. The rocket ssto needs high fuel fraction and low dry mass. So long as it can take off and get supersonic the rocket one doesn't have to worry about lift or drag too much, it quickly blasts out of the atmosphere. The retrograde orbit and the amount of payload - crew cabin for 6 seats and a cargo bay - make this a fairly demanding job for an ssto at this tech level. Tough to do it without building an enormous craft whose fuel tanks/engines dwarf the actual payload.
  6. I have built many liquid fuel only SSTOs, the problem with yours is that it has far too much fuselage drag and far too little lift (wing area). With Whiplash engines i prefer to get my speedrun about 17km in level flight. After that raise the nose gently so it's pointing just 5 degrees above prograde after starting the nukes. With nukes you always have low TWR because they are heavy and weak. Your craft can still gain energy so long as the goodness of your lift to drag ratio exceeds the badness of your TWR, to use simple language. Optimum lift drag ratio in high speed flight is when the nose is 5 degrees above prograde, so that is what you should aim for once the nukes are on. In KSP about 80% of the drag is from fuselage parts. The ideal for a liquid, nuclear spaceplane is to put all your fuel in Big S wing parts, but as that tech is not available to you, I'd say go with mk1 liquid fuel tanks instead. Mk2 parts look nice and have good heat tolerance, but they make twice as much drag as mk1 parts with the same fuel capacity. They only really make sense for kerbal containing bits, since they give twice as many seats per part which offsets the higher drag. And for the love of god, give it more wing area. Like four or five times as much. I put this together really quickly, trying to base it off your design as much as poss. https://www.dropbox.com/s/qpnu93jw84yhhgz/snouty.craft?dl=0 This ran out of fuel just before circularising ! So i redesigned it with 2 more mk1 liquid tanks. Whilst i also converted the crew bits to mk1 size, it may not have been the best move on account of how hot they all got. https://www.dropbox.com/s/01t94h8kja37fp8/snouty2.craft?dl=0 We made it though
  7. I'm not much good at rovers, but it generally looks like an oversteer problem, as in the same thing that affects auto racing. Airplane landing gears in KSP suffer that too. You need to go into friction control override and make sure the front wheels have less grip than the rear, so they loose traction first. That stops the back end drifting out. The other thing seems to be that those wheels are giving you too little friction overall for the mass of the vehicle, under Duna gravity. It slides sideways for ages without stopping like it is on sheet ice. You might need beefier wheels. Building a fast and safe rover is very difficult in this game however, so i'm not sure how good a rover can be.
  8. I studied a bit of biochemistry a while back, so from that angle : Heat - human metabolism is only about 20% efficient converting the chemical energy into mechanical work. The other 80% ends up as heat. So, when i'm on my bike I can do a 1000 watt sprint (just under one and a half horsepower) for a few seconds. During that time I'm generating 4000w of heat. My aerobically sustainable output is 220W. That's a mere 900w of space heater boiling my blood. Fat is our most energy dense fuel source, and gram for gram it stores almost as much energy as petrol/diesel products. Unfortunately our bodies have trouble burning it quickly. Much over 100w and and the energy starts to come from Carbohydrate instead. Why is this ? Well, it probably doesn't help that fat is not water soluble, and our metabolic reactions are things that happen to stuff thats dissolved in our body fluids, for the most part. Second, carbohydrates are made into fats by stripping off their oxygen molecules. Carbohydrates have a roughly equal number of oxygen , hydrogen and carbon atoms in them. But oxygen is in the air all around you, so get rid of them to improve the density of your fuel. Except that oxygen atoms have a stronger affinity for electrons that carbon and hydrogen, resulting in that end of the molecule becoming "polarised" with a slight negative charge. This makes it easier for enzymes to latch onto and react with them, and allows them to dissolve in water. Third reason, we're not a migratory species. So what about carbohydrates as a fuel source ? Well, they only give 4 calories per gram unlike fat which does 9 calories. In practice, they are even less dense, because they are hygroscopic (attract water). Your body only stores about a kilogram of carbohydrate (enough to last about 90 minutes) but that kilogram attracts 3 or more kg of water weight. Still more energy dense than batteries though. So, our super human could be engineered to not store energy in the form of fat at all, and store all of their excess calories as glycogen. Or we could somehow invent a way to make fat burn as fast as glycogen, then happy days. The other thing you could do is jack up our body temperature. This will make heat dissipation more efficient, and should also increase the rate of the chemical reactions in our body. However you'd have to redesign all our enzymes and proteins to not break down in the heat. There's no such thing as a free lunch either. Enzymes that are more stable at higher temps tend to suck at lower ones. These super soldiers would have to maintain this higher body temperature permanently or else suffer hypothermia. Nature already does this - birds have a higher body temperature than mammals. So to summarise - super soldier with no fat storage, all excess calories stored as glycogen, and higher body temperature would do much better than a normal human if asked to run as far as possible in 24 hours with a heavy backpack. However, owing to their less efficient energy storage, and higher basal metabolic rate to maintain the higher core temp, they'd do terrible at surviving a famine.
  9. Anybody made one? I'm ok with the SSTO part, but have never really made a flying wing. This is about as close as i ever got, but it still has some naughty vertical surfaces. Gotta have that yaw stability. Also, think it got hit rather badly with the ugly stick. It shifts though. Looks to have quite a bit of delta V (as you'd expect, given there's no payload beyond Jeb) https://kerbalx.com/AeroGav/korten-fledermaus
  10. You've done a decent job putting the engines amidships so it should stay balanced. Like that you're using Big S wings as tailplanes to keep part count down. The big key to making something so huge is coming up with a layout that doesn't cause it to break apart through an overstressed joint. As for the "what's the point" ? Argument, you could say the same about my largest creation. It's pretty small compared with that thing (we could call its payload 120 tons if we allow 0.5 tons per kerbal) but still fairly ludicrous. Why would you ever need to transport 225 Kerbals to orbit in one go ? Coming back to the game after some time out, the surprising thing is how nice it flies (compared to some of my recent experimental creations as i relearn the game). Yeah you can snap the wings off pulling more than 4g (like an airliner) but it tracks really straight.https://kerbalx.com/AeroGav/Monstrosity-225L
  11. I haven't played Kerbal for a year, so this is a bit tricky. Anyway, this is probably the tiniest liquid fuel only entry you're going to get. 8 tons, two junos, one nerv, 540 units of liquid fuel is all we need. Bill even gets a proper capsule ! https://www.dropbox.com/s/fegeqs11z7p8f0c/jUNOVATOR3.craft?dl=0
  12. Press ALT F12 in flight to bring up the console menu, go to physics, aero section, then tick the box to show aero data in action menus. The mk2 body parts have less than a 10th of the lift of a wing part and more than 10x the drag. It's not right but i guess they can't buff it because it could break existing crafts. Note that all this drag up front does actually torque the nose up, particularly at high angles of attack. This is why you are having to use "huge wings at the back". The stock centre of lift indicator does not take into account aero forces from nonwing parts properly, so for a lot of aircraft with a long neck and an AFT CoM, it can be way wrong. There is a mod called CorrectCoL which gives a more accurate indication - on the last airplane i worked on, the stock indicator showed the blue ball well behind the yellow CoM marker, they were only touching by their edges. Switch to CorrectCoL and it turns out CoL and CoM were in the same place.
  13. I have built quite a few staged spaceplanes. The vehicle editor makes piggy back airplanes harder than they need to be. If you are new to this, I recommend just trying a variant of the normal spaceplane ssto with engines on detachable pods hanging under a high mount wing. That way when you blow them off, they are close to centre of mass and won't cause the plane to become nose or tail heavy, and by hanging them underneath a high mounted wing, the thrust should be in line with centre of mass too. A similar approach can be taken with regard to drop tanks. Take a look at this simple, low tech one - Download it here if you want - https://kerbalx.com/AeroGav/Kranker Or this more whistles and bells one - (download from) https://kerbalx.com/AeroGav/Learstar-A2 Think about the components of spaceplane that don't need to go all the way to orbit - 1. Panther and Whiplash engines - punch em off ! They cost under 2000 kredits each , less than a third of what a rapier does, but are still quite heavy. The second example I posted would normally need two or three Rapiers to get through mach 1, but with 2 panthers to get us to mach 2, a single rapier is able to take us to mach 5 because of the ramjet effect at high speed. An all rapier design would only get slightly faster airbreathing, because the Rapier thrust curve rapidly falls between mach 5 and 6. 2. Rapiers - keep to orbit See above. Too expensive to chuck away. 3. Empty fuel tanks - punch em off ! The issue is not so much the weight of the empty tanks, but the drag they make in an atmosphere. Most of an airplane's drag comes from fuselage parts in ksp aerodynamics. 4. Wings - keep If the part of the airplane that continues to orbit is nerv powered and liquid fuel only, you'll definitely need those wings. NERVs get great ISP but they are heavy and low thrust, so any vehicle with a decent fuel and payload fraction will have TWR less than 1. This is actually fine, provided your lift to drag ratio makes up for the weakness of your TWR. With sleek mk1 size fuselage parts, a generous wing area and moderate angle of attack (5 degrees) you should be able to manage lift to drag > 3:1, meaning the orbiter stage will fly fine on a TWR of 0.3 or better. Tip - ideally, don't use any fuselage tanks at all on the orbiter stage. Big S wing and strake parts contain all the LF NERVs are able to haul out of the atmosphere on their own, and the drag/fuel capacity ratio is much better with wing parts than fuselage lf tanks. Idea for a three stage design - If the orbiter, NERV stage is really underpowered, it may be unable to accelerate after the jet engines quit. However, if you can get up to 1700-1800 or so, even a single NERV design can make it the rest of the way, because you are approaching orbital velocity which reduces the craft's apparent weight. This in turn allows the wings to get it up into the really thin air at 35km or so, where there's not much drag. So, some cheap LFO engines and tanks on drop pods under the wings can bridge this gap for you. I've built some for earlier versions of KSP, can't guarantee they still work. This is another retired stock craft I did some upgrades to, the Stearwing. Originally a Whiplash/Terrier 2 stage, I made it into a 3 stage Whiplash / Spark / NERV. Here it is undergoing kerbal-rating qualification, you can see the staging sequences.. https://kerbalx.com/AeroGav/Stearwing-D45N-Lite
  14. Well, I started designing a new airplane for this job, and predictably enough i'm running into issues "unsticking" from the water. I think i got lucky with the "puffin" pictured in my previous post. I gave the wings sharp dihedral and had them extend below the fuselage at the centreline, so the innermost/lowest parts of the wing dip in the water and act as hydrofoils. Problem is, when you try to pitch up , the front parts of the wing come out of the water, so the centre of hydrodynamic lift goes well to the rear. That is to say, it really does not want to pitch up at all, and the faster it is going, and the higher the airplane rises out of the water, the worse this gets. Also when you do manage to generate some pitch angle, the rear fuselage dips into the water slowing you down. I eventually got it to unstick at 90m/s (twice the speed it lands at, with full tanks) and then it goes into a vertical climb. So, guess i need to start again. attempt 2.0 will have flat wings, and i'll make separate hydrofoils that extend well below the fuselage, i'll have to make the front ones have tall "legs" so they stay in the water when the airplane is pitched up. The problem with this, is that it's surely going to mean no ground clearance , or almost no ground clearance when land based. Perhaps i should just remove the landing gear completely and have it launch from the runway on a dolly, after that it will only ever see air, space , or water.