AeroGav

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About AeroGav

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  1. AeroGav

    Some SSTO questions

    I've been playing Lord of the Rings online most of this year but came back to KSP because compared to learning a zillion boss fight dance moves, repeatable quest timers, and locations of all the vendor npcs, building airplanes in KSP is really accessible and something you can just drop in and out of at will. Also it has a pause button, KSP lets you pee. This is important. 3. For 30 tons, a lot of things work. One Whiplash two Nervs ? 2 Rapier 1 Nuke ? 1 Rapier 2 Nukes? All can do the job. My last endgame build was a 40 ton crew transport, 2 nukes, and one panther and one rapier clipped into each other to avoid asymmetry probs. That combo covers all speed regimes pretty well. Flight profile : I don't like thinking in terms of this pitch angle , that pitch angle. Pitch depends on your payload and TWR, the optimum changes throughout the flight. But the optimum AoA does not. For wings that is 5 degrees. For every other part it is zero (prograde). During the speedrun, you want to get as much velocity out of air breathing mode as possible. This means getting into level flight at about 21km, and holding that until acceleration starts to die away . You should be able to do 1400 - 1500 m/s, but engine thrust falls away rapidly thereafter. You are probably holding the nose down during the speedrun, to stop the plane climbing. Up to 21km thrust declines more slowly than air density (on the RAPIER) , which is why it's a good altitude for the speedrun, but after that it falls away more quickly than air density (drag). Once you've lit the nukes, it's time to forget about pandering to your jet engine's intake needs, the only thing that matters is lift to drag ratio - you maintain the AoA that gives best exchange rate possible. If the plane climbs, it climbs, if it then starts descending for a bit before heading back up again - let it. Just nail that AoA sweet spot to minimise drag loss. You can sort of see from this one, i'm holding the nose down a bit to maintain level air breathing flight at 21km till we reach 1500, then i start the nukes. At this point, i let the nose rise back to prograde again. The wings are angled up at 5 degrees so they are at 5 degrees making lift while the rest of the airplane is on prograde for low drag. I'm tweaking the deployed flap surface to keep the nose close to prograde. Now, when i stop pushing the nose down we end up with an excess of lift and immediately start climbing. In that video, I'm doing 1800 when i pass 30km, and am climbing at a three degree angle.
  2. So, I got thinking about making something that could do the job of Matt Lowne's old ship, Argus, in 2018. Requirement is 4 seats, 4k delta V in orbit, and at least a CRG-25 bay. The adapters either end of the cargo bay add waay more LFO tankage than i'd want (looks to be enough to add about 3-4 mach numbers to something this size), so i'll scale up to a CRG-50 right away and see where that gets us. The delta wing makes it look like it's doing 0.5C while parked, unfortunately the CoL is WAAY too far back. Yes, I accidentally clicked away, and lost, the front section, but it didn't move it forward much and unless i give it canards like Dumbo's ears we'll still be too far back. I really want the CoM to be in the middle of the cargo bay so it handles the same laden or not - and fuel needs to be distributed either side of our CoM too. I tend to build lower powered designs that compensate with low drag. But it will only have low drag if prograde hold keeps us within a degree or so of prograde throughout the the mission. One other problem with this sleek wing - I need to find a place to put on 2 RAPIERs and 4 NERVs. Once I add incidence to the wing, there won't be any place i can attach these to the body and not have the efflux impinge on a wing surface - unless i put all the engines at the back - which will put our dry CoM way behind the cargo bay. Anyway, I digress. Subject for tonight, Rhinoplasty. This reminds me of Sesame Street character, can't remember the name. Quack ! Ramp intakes, sloping inward. Hungry for Krill.... Ramp intakes sloping out. Pointy. Looks like i used some old parts off a Colonial Viper. Edit - craft name will change, don't worry. The pre-alpha had the cabins between the panther engines and rear tri couplers, it looked a bit medicinal, you could say.
  3. AeroGav

    Matt Lowne's SSTO Emporium

    It's the gravity assists he pulls off that i could not possibly replicate. I did write a spaceplane tutorial last year. The Argus is an old design. Payload fraction / Delta V are what define SSTO "efficiency", the Argus has good Delta V (4300 from LKO) but it is mostly fuel, and doesn't carry many Kerbals for its size. Most of my ready made SSTOs are designed to carry lots of Kerbals to Minmus or Duna easily, but I think if you're going further afield it makes sense to do mining or have a refuelling stop on Minmus or Duna. https://kerbalx.com/AeroGav/MK1-Griffon-Deep-Space-Crew-Shuttle 11 seats and 3000dv in orbit for 40 tons. I did make a version with 2 of the cabins swapped for fuel tanks https://www.dropbox.com/s/xiwg7m7c47u1oyp/Griffon SP.craft?dl=0 .. and an even more hopped up version for @septemberWaves and her rescaled solar system - the whiplash engines were jettisonable and it had >4k delta v in orbit with 0.6 to 1 TWR on its nukes in orbit. https://www.dropbox.com/s/v3enet77pm1jl5i/Starion2.craft?dl=0 Why don't you spin this off to a challenge, to make a 2018 Argus replacement - state the requirements and let people submit their craft - presumably needs 4k delta v, at least 4 seats and a small cargo bay? As regard instructions , all my craft on KerbalX have them, and some have videos showing the launch process too. If you've not flown any of mine before, https://kerbalx.com/AeroGav/Auto-Ray has detailed instructions and a video. It's quite forgiving too, but as a caveman tech design it hasn't got the performance you're after.
  4. AeroGav

    Landing Gear Weight limits.

    My latest ssto was one where i went for the lowest tech option for every part except the NERVS - so i used 5 small landing gears instead of 2 medium and 1 small. I must say. it is very stable on the ground as a result. One wheel up front, one pair just behind CoM a little way out from fuselage, and the rearmost anti tail strike pair on the tips of the delta wing at the back. Coming back from space empty, touchdown speed is 25 m/s and it is immune from cartwheeling. You can land just about anywhere.
  5. AeroGav

    Spaceplane handling

    Stability wise, you are doing most things right. However, the mod "CorrectCoL" shows that your airplane is trimmed to fly about 5 degrees nose down when "hands off" ie with no inputs from you or SAS. I presume you are trying to correct this by using SAS in its default "stability assist" mode. The problem is SAS is a terrible fly by wire system. It just tries to hold the nose at the same angle (relative to the sun) that is was at last time you touched the controls. So, over time it "learns" how much nose up input to apply to fight the plane's aerodynamic tendencies, but every time you touch the controls (such as to roll the wings) it resets so the nose falls quite some way. Fix the excessive nose down tendency and stop using Stability assist mode as a crutch, everything else falls into place. This is my "minimally changed" version - https://www.dropbox.com/s/r0nm6cashlw6v30/Heavy Lifter MINMOD.craft?dl=0 What I did was use the fine rotation tool to reduce the incidence of the rear wing. It makes a bit less lift, but the front wing is at a bigger angle of attack, and starts to stall first when the airplane is at a high AoA. As a result the plane flies 2 or 3 degrees nose up with SAS off and no-one at the controls, but if you yank the stick back hard you can't get it to pitch more than about 10 degrees. It's a space plane, not a fighter, no need to pitch that much even on landing. Most of the time you'll probably use Prograde Hold SAS mode in flight, which cuts the AoA down to about 1 degree nose up. I made a more heavily modded version too. https://www.dropbox.com/s/pt2emjl7fdmxs05/Heavy Lifter2.craft?dl=0 The original has a lot of empty tanks that are just making drag. Even the above version is crazy overpowered. Full nose up until it's climbing 40-45 degrees on takeoff to stop speed getting stupid down low, then go prograde, it levels off about 18k by itself, gets over 1500 m/s air breathing. In rocket mode, TWR is over 1.15
  6. For your climb rate to increase, your lit from orbital freefall effect + lift from wings + thrust component from engines thrusting downward has to be > weight of craft So if you're already at 70% of orbital velocity, a TWR of 0.8 will be more than enough to overpower the craft's remaining weight. Here is an example of one of my spaceplanes using these effects - TWR (2 nukes running) 0.44 1577 m/s so about 75% of orbital velocity Lift - 115kn Drag - 35kn Thrust - 120kn Weight is shown as 246kn, but since we're approaching orbital speed over two thirds of that is getting cancelled by the centrifugal force of hurtling around the the planet. Our climb rate is 147 m/s and increasing..
  7. AeroGav

    SSTOs! Post your pictures here~

    While uploading my plane, I spotted this mad thing on KerbalX. It's 1Straycat's only upload. Look at how many passengers this thing carries - and how much delta V it's got (nearly 6k!) yet the body is entirely given over to cabins. I thought making something so large out of mk1 parts and a welter of strakes would be a floppy noodle nightmare, but it actually flies good and is more robust than you'd expect. https://kerbalx.com/1straycat/APSSTO-7 Well, of course I made my own version, liquid fuel only (apart from a locked FT100 for the Vernors). Went down from three Rapier to two, but added two Panthers to give it a bit more low speed umph. Added an extra nuke, deleted the oxidizer tanks. Overall mass down by 10T. It only has 4800 delta V in orbit, though TWR better in nuke mode. Once the RAPIERs quit, TWR drops to 0.21 - but the lift/drag ratio in hypersonic flight is so good, it continues to gain energy - slowly. Oh yes, and about the durability. I wanted to fly it into some KSP buildings, but when you chop the throttle on this thing it just floats and floats and sailed over the top of the thing i was trying to crash into. Eventually on the third attempt, I managed to hit the VAB with it.... The cockpit is still there, and I'm counting the same number of cabins as it had before takeoff. Crumple zones FTW. The VAB was totalled, fortunately it's a weekend so no Kerbals were in it. My version here https://kerbalx.com/AeroGav/APSSTO-8
  8. AeroGav

    SSTOs! Post your pictures here~

    https://kerbalx.com/AeroGav/Krakenskimmer-Mandalay-class-SSTO A thread came up asking for Panther spaceplanes. To be honest I don't think you can do very much on a pure Panther / Chemical design, other than reach LKO with a small payload fraction. Maybe by going very large, you can make something that does a worthwhile task in career mode, but i've not much experience in "moar boosters". However, I know a thing or two about optimising hypersonic lift / drag, so if you add NERVs onto the caveman airplane tech, you can actually make a nice little runabout. I'm really pleased with the appearance. With a full tech tree, it's Big S strakes are pretty much the only aero surface you want to use, their advantages are just too great. But with them off limits, I get to use the modular wing parts and was able to create some nicer shapes - though overall planform was dictated by the need to get dry CoM, wet CoM and lift into the right places.
  9. @Vegvisir Not wanting to reinvent the wheel, I took something based on your craft to produce the next step - a Panther/NERV SSTO. I kept the basic fuselage layout (small cargo bay, mk1 cockpit and crew cabin) , but added more wings since we need good lift/drag ratio in hypersonic flight if your propulsion is as weak and heavy as a nerv. I'm quite pleased at how it ended up looking, those mk2 parts are certainly pretty, and i don't normally go for modular wings (preferring fuel containing big S parts) but doing so gives much more control over how the craft looks. By the time I added incidence, control surfaces, and tweaked wing locations for correct centre of litt it has lost some of its sleekness, but still looks better than what i normally make. That's the upside to enforced low tech ! Fuel ends up in pods either side of the cargo bay, which means no CG shifts as the fuel burns off. That means an airplane that holds closer to prograde throughout the flight, which means less drag - as well as being nicer to fly. Two Panther and Two Nervs. I was going to make it completely LF only, but that means not using the oxidizer tankage of the mk2 adapters. On Prograde hold mode, she does 0.65 deg AoA on Prograde hold, with no input from me. If you take SAS off and let aerodynamics do their thing, the nose rises a little more - to 1.4 degrees Around 8 or 9 km, there isn't enough lit even at this angle to maintain our climb. The inboard elevons are bound to action group 1, and push the nose down a couple of degrees when selected, which puts us in a low drag mode for crossing the sound barrier. After crossing mach 1, lift increases dramatically too, and i'm using this action group intermittently to try keep us from bobbing over 14km when the jets start to loose power. After porpoising up and down a few times , we eventually hit 750 m/s in level flight at 15km. I start the rockets and cancel the nose down trim. The oxidizer runs out about 1500 m/s. Eventually, after some imid course corrections and over corrections, we end up here - Plenty enough fuel to land and go back to Kerbin, though you need a horizontal landing vernier system for a really stylish rolling touchdown on the flats. Could drive to several biomes this way, it doesn't use much fuel on the ground ! https://kerbalx.com/AeroGav/Krakenskimmer-Mandalay-class-SSTO file here !
  10. Glad to see you're making progress. For incidence angle, I'd go for 5 degrees rather than 2 - 5 is the optimum angle of attack for lift at supersonic & hypersonic speed, so that's what we care about. Rather than fly the plane with SAS on Stability assist mode, you can then try flying with it set to Prograde Hold. This will significantly reduce drag. Note, you've added incidence to main wing and the canards, but not the strakes inbetween. The strakes will therefore stall last, and being in front of CoM, will keep making lift when everything else has quit, and send you nosing up into a deep stall. Remember kids, stuff in front of CoM should have same or slightly more incidence than stuff behind it . If this makes her adopt too much of a nose up attitude in "hands off" flight, move the wings back a bit ! What's your flight profile? Top speed on the Panther will be in level flight at about 14km up. You should be doing at least 750 before starting rocket, though after 750m/s power falls away very fast. If you can't keep your AoA down while doing that speed at that altitude, you deffo need more wing. Ideally you should have enough wing to do that altitude on prograde , with only the lift from wing incidence. Your screenshots are tiny but it looks like you were getting lift to drag ratio of about 1.6 to 1 in the middle picture. That's horrible ! My "Stretch Ray" was getting 4.2 to 1 at 19km and 830m/s. AoA is mostly to blame. Can you put those solar panels in the cargo bay? You're only going to need them once you're in space, keep em out of the wind till then. Attach them to a cylindrical thingy within the bay, maybe your science junior. Likewise, you could stick it on the side of the science junior within the bay. Engine Nacelle intakes - minor thing, but it doesn't need that much intake area if you already got two circular intakes. A single mk1 liquid fuel fuselage on the back of the main fuselage would hold just as much fuel for less drag. MK1 rocket fuel fuselage short - behind the cargo bay. Like i stressed in my space plane guide, don't use mk2 parts unless you really need their unique capabilities. An ft-400 tank holds the same amount of rocket fuel for about a third as much drag.
  11. https://kerbalx.com/AeroGav/Basic-Tourist-SSTO Panther Terrier 30 part ship - 3 seats to LKO. On a technicality , this also counts as a "pre whiplash SSTO". Liquid fuel only panther/nerv thingy that can go a bit beyond LKO actually. Beyond the NERV motors, the rest of it is pretty much caveman. https://kerbalx.com/AeroGav/Stretch-Ray BTW, I like plenty of wing, especially when you have TWR < 0.5 in upper atmosphere thanks to NERV engines. Hypersonic motor glider, that is what you are building. 4 Star Euro NCAP Rating too, protect your most experienced Kerbals !
  12. AeroGav

    [1.4.+ BETA] Kerbal Wind Tunnel

    Perfectly acceptable on my Ivy Bridge Desktop I5, though I've been watching the World Cup on my second monitor and the calculations make that stutter (thread priority?). Despite which I seem to do a better job spotting fouls than the V.A.R., but that's another topic. @linuxgurugamer very glad to see you're continuing the work, I thought it was a dead project because Google only brings up the old thread. You must have fallen out of favor with the Illuminati
  13. AeroGav

    [1.4.+ BETA] Kerbal Wind Tunnel

    OFF-TOPIC but someone really needs to come up with a replacement for @Boris-Barboris 's CorrectCoL mod. Andromeda has the noob error of insufficient pitch stability, especially when empty I'm ashamed to say. For me, we need something that takes account of drag from non-wing parts, and was also a big fan of the static stability graph. You could see at what AoA the airplane has neither a pitch up or pitch down moment, by where the line crossed the X axis. I was aiming for a very small positive AoA, being the one it would fly at with no hand on the controls. You can see whether the plane's nose down tendency gets stronger as the node continues to rise, or if it reverses and goes flip happy because the front wing stalls first. I've had to manually correct Andromeda by making countless test flights 1. move engines forward a bit , move fuel tanks aft a bit so that hopefully CoM doesn't shift when fuel burns off (have as much fuel behind CoM as in front of it) 2. Now make flight after flight , shifting the wings around so it's stable with the new CoM position, then dialling in the right amount of built in angle on the surfaces so it holds a small positive aoa with no input 3. tweak trim flap deployment angles so you get about 5 degrees +- with SAS off and +- 1.5 degrees with it on I've now got it so the plane flies at +1 AoA with SAS off and trim neutral, with trim up action group, it's 5 degrees nose up with SAS off and 1.5 with it on, -5 with nose down set and -1 AOA with nose down set on prograde hold. Full back stick gives about 15 degree nose up. That took 2 hours, would have been 5 minutes without test flights if i still had correct CoL. That's just the testing with full tanks. To do empty, i need to manually empty all those strakes by the same amount, or leave the nervs running with parking brake set on the runway for 20 minutes. I've updated the craft file just now and might do it again if i get time for more ksp next week.
  14. AeroGav

    [1.4.+ BETA] Kerbal Wind Tunnel

    Yes, that describes things :-) Kick ass mod, first time i've seen a flight envelope in KSP. Do try adding that orbital freefall thing though. You wrote this mainly to deal with the problem of getting supersonic , at such low speeds its not a factor and in any case, lift does not have to = weight when crossing mach 1, you can always go prograde for that bit of the flight even if it sends you arcing into a dive. During the speedrun, most of my planes, Andromeda included , have a bit too much wing, and especially when empty, trying to maintain 20km for the speedrun is like trying to hold a polystyrene block underwater. The graph doesn't really show this. Once you are done with airbreathing, i go prograde for best L/D ratio and the excess lift results in a positive rate of climb. It starts to run out of lift by 35km, but you're over 2000 m/s at that point which causes the climb rate to start increasing again.
  15. AeroGav

    [1.4.+ BETA] Kerbal Wind Tunnel

    It is a liquid fuel only cargo ssto. First stage starts both panther and both rapier together. Second stage starts the nukes. The rapiers are only ever used in air breathing mode and the oxidizer tank at the front is empty. But it can still put a full orange tank in LKO :-) I suspect the drag values are far too high - is it getting confused about whether the cargo bay is open or shut , or does the wing incidence upset things?