Lt_Duckweed

I actually did a few years ago! We did a collab project for the Jool SSTO video on his channel

Naughty Kerbals get banished to the Sun

The vector will indeed be shielded by the fairing. But the fuel tank is not "in" the fairing, nor is it node attached to the fairing. Thus, from the perspective of the fuel tank, the fairing might as well not exist. As for the vector being node attached, keep in mind it only reduces the exposed area commensurate with the size of the vector. Since the vector is about 1/2 the radius of the fuel tank, it reduces the exposed area of the fuel tank rear face by about 25%

Fairings apply all their body lift and drag at the base of the fairing, so that front fairing facing backwards is applying most of your fuselage lift and drag far forwards of the CoM. As for the high drag of the fuel tank generating high drag. You mention that the tank doesn't have an open back, but the thing is, it does. Attaching things to nodes reduces area of the associated drag cube face based on the size of the drag cube of the part you attached. In the debug data in your screenshot, the drag vector is (0.1 , 1 , 0) which means YP is the frontal face. This has a OccA of 0, and a WDrg of 0, so all good there. But your rear face, the YN face, has a OccA of 3.73 and a WDrg of 0.92. Comparing the OccA of 3.73 to the WArea of 4.85 means that the attached vector reduced the OccA by only 1.12 (4.85 - 3.73). On top of that, a WDrg of 0.92 is really bad. That's pretty much indistinguishable from a flat plate. Thankfully this is a rear face, so by the time you are approaching the speed of sound it will reduce quite a bit (rear face drag falls off substantially above ~Mach 0.9) EDIT: to add on to this, I would highly recommend installing the mods "CorrectCoL" (take all parts into account for CoL indicator, not just wings, and also gives stability graphs) and "RCSBuildAid" (see separate indicator for dry CoM) as they provide invaluable help when designing planes.

Note I did not dispute the authenticity of your statement as it regards cargo bays, I am well aware of the ongoing revert bug with root cargo bays. I disputed it as it regards fairings. I have tested this many times, as recently as today. Root fairings do not suffer from the same revert bug as root cargo bays. I have spent quite a lot of time testing and reverse engineering the KSP aero model and looking for edge cases. I have spent a lot of effort to make sure the information I distribute is accurate, and have a series of well respected deep dives on the aero model posted on my youtube channel. However, I have always encouraged others to independently test my results. So, feel free to install KSP and find out what has changed in 3 years.

Fairings shield parts from drag just fine when the root part. As a matter of fact, they do better than that. Fairings that are the root part do not themselves generate drag with their fairing panels, only the fairing base. So an arbitrarily large root fairing can shield as many parts as you want while itself having nearly 0 drag. The last time root fairings didn't shield parts from drag was update 1.4. Spreading bad/outdated info while speaking as if from a position of knowledge is a huge problem in the KSP community and is in large part responsible for why so much inaccurate or outright false information still circulates even many years after it ceased to be true.

Das me.

Using a 0.625m nose cone on the back face of a rapier will only partially remove the back face drag, since it only occludes 1/4 of the back face area. To fully remove it you have to use at least a 1.25m nose cone.

Based on the images of the deconstruction it looks like you attached the whole isru kit to the bay end node and attached the cockpit to the isru setup, then offset. This means you have spindly, offset joints, which can be prone to breaking. Attach the Cockpit to the cargo bay directly, then attach the isru to one of the nodes on the inside of the bay. Also, for what it's worth, your current radiator setup is extreme overkill. Since the drills are attached to the fuel tank, and the isru to the cargo bay, a single large fixed radiator panel on the bay and 2 on the fuel tank is plenty.

Might as well throw this into the ring:

The key here is that when a fairing is the root part, the fairing panels do not count for drag. This means that making it pointier does not help. What you have to do is occlude the fairing base via node attachment. In your screenshot, the YN face OccA value is almost 0, as that is the bottom of the base and is attached to the fuel tank, which almost fully covers it. However, the YP face (which is the top of the base) OccA is 1.03, which isn't very covered at all, and the Wdrg value is 0.91, which is very blunt. You can fix this via enabling interstage nodes on the fairing and attaching parts to the forwards facing interstage nodes until the YP face OccA and Wdrg values are down to reasonable levels (a Wdrg under .4 should be the minimum target). This can be many small parts, such as cubic struts, or one larger part, such as a 1.25m nosecone.

771 m/s remaining in a 72.5km x 72.2km orbit. Tilted over to 70 degrees above horizon by 110m/s then full throttle till apoapsis leaves the atmosphere, then circ at apo. Next attempt, tilted over slightly faster, 70.9km x 70.3km orbit, 781m/s left

I've noticed that this is actually an issue at high altitude on Eve since the temp drops sharply with altitude, but for the speeds an Eve ssto reaches before turning on engines, it's a pretty minor gain for a lot of pain babysitting the prop rpm, so it's easier to just let it rip.

ah, in that case, can you detail how you have the rotors and props setup in terms of torque, rpm and blade angle? I always run the props at max rpm, and adjust the prop angle such that the prop AoA is 4.5 degrees, or the highest AoA that can be used before the prop rpm starts dropping, whichever happens first. (In thick atmosphere you will have to run a lower AoA to maintain full rpm, as you are torque limited. In thinner atmosphere you can run 4.5 degrees, which gives maximum thrust, at max rpm, as you are rpm limited, not torque limited)

Adding rapiers to an Eve ssto for Kerbin takeoff is pointless dead mass and makes ssto'ing off Eve essentially impossible. Wrong. Propellers can get a craft airborne on Kerbin and Eve just fine. All sea level Eve sstos using breaking ground take off using propellers. Wrong. You need propellers to get up to the altitude where your engines will get good thrust and ISP. You don't even ignite your engines until past 15km. @king of nowhere the main problems I am seeing with your craft are this: 1. Not enough prop blades. You have 16 total, 8 per rotor. At this mass you need to be using about 32 total. You can do that via 4 rotors with 8 blades each, or if you offset the prop blade base one tick past the axis of rotation (so that the base is on the other side of the axis from the rest of the rotor) you will need substantially less torque and thus can do 16 blades per rotor, but with this setup you have to be very careful as if the blades stall they will kraken. (This setup also makes the prop compact enough to shield in a 1.25m service bay, though it looks a bit clippy so you have to decide if that is something you are ok with). 2. Too much engine mass. Margins on Eve sstos are very tight, for a craft of this size you should be looking at ~2 vectors, meaning you are carrying 7 tons of dead mass. Swapping to 2 vectors also means you can mid mount them, so that their dry mass is in line with the CoM and thus does not drag the CoM around as fuel drains. 3. Props too far forwards. Eve sstos, in order to not carry too much wing into the rocket phase of ascent (and therefore climb too rapidly) are under winged and therefore must adopt substantial angle of attack through the upper prop phase of Eve ascent or on Kerbin takeoff. This means the props are crabbing through the air at an angle, which causes all sorts of issues thanks to them being very far from the CoM. Move the props to mid mounted side pylons (or do one fore and one aft to cancel each other's stability effects). Additionally, I angle my props downwards 5 degrees on my Eve sstos, to better match the AoA in upper Eve ascent (this makes it even more important to mount them at the CoM, so the thrust axis points through the CoM) 4. CoL too far backwards. Your CoL being substantially behind the CoM means that you have to actively fight the craft to get the nose up AoA for upper Eve prop phase, and for Kerbin takeoff. You want your at rest CoL lightly ahead of your CoM, which you do by mounting your main wing slightly forward of your CoM. Doesn't have to be much, just a couple of ticks. Then to counter the resultant instability this would otherwise produce, you place your horizontal stabilizers as far aft as you can, and with 0 wing incidence. This means that when you pitch up, the horizontal stabilizers will gain lift proportionately faster than the main wing, since the main wing has angle of incidence already built in (wing lift is ~linear up to about 15-20 degrees AoA, so a pitch up from say 5 AoA to 10 AoA would have the main wing go from 5+5 AoA to 5+10 AoA for 50% more lift, but the horizontal stabilizer would go from 0+5 AoA to 0+10 AoA, for 100% more lift). This results in the CoL sliding backwards as you pitch up, providing stability, just at a non 0 pitch up AoA. This makes it much much easier to fly at a non 0 AoA as it won't fight you nearly as much, and it means the craft can adopt a substantially higher AoA on reentry since the passive stability will not be fighting nearly as hard to revert to 0 AoA.

It works with the LVN, it sounds like you didn't offset far enough. I use this trick on most of my spaceplanes (though it should be noted that this effect is not as large for the nerv as it is for some engines, like the rapier (rapier has an extremely blunt end so has high backface drag)

The aerospike is a fairly aerodynamic engine when node attached, and shouldn't be creating large amounts of drag. Are you sure it's actually node attached and not surface attached? Hold alt while placing the aerospike to disable surface attachment.

Oh, one more question, is the cargo bay the root part? That sometimes causes issues, and the solution is just to make one of the other fuselage parts (either the fuel tank or the cockpit) the root part.

Everything has a drag vector with aero forces turned on, it will just be extremely short for things producing no drag, like the wheels appear to be. The aero forces view is a bad way to tell what is producing the drag anyways, since the vectors don't have a consistent scale. If you want to actually tell exactly how much drag a part is producing, do this: Alt-F12 -> Physics -> Aero -> Show aero data in part action windows. It's hard to tell from the screenshot, but it looks as if most of the drag is coming from your fuselage itself, and not what is in the fuselage.

Class I comets are the largest comets, and always spawn on hyperbolic escape orbits from Kerbol. So they swing by periapsis one time, then sail off into the distance, never to be seen again.

That's is because it is a basic advanced spaceplane tutorial. It's intended to be as simple as possible. But the craft in the tutorial could be even more efficient if it used nerv engines and didn't have oxidizer. All of the following SSTOs use no oxidizer at all: This one does use ox, but only on a technicality (it has to use a small amount to power the fuel cell)

This is incredibly false. Like, bafflingly so. The most efficient spaceplanes for LKO all use only liquid fuel, swapping directly from airbreathing rapier to nerv powered flight. While that is a bit beyond the current skill level of OP, having a few nerv engines to help reduce the amount of oxidizer they use on ascent and circularization, and more importantly, for the burn to the Mun, and as much of the Mun landing, and later ascent from the Mun and return to Kerbin, will vastly reduce the amount of fuel they need to carry. The number of nervs they have right now is overkill, but so is the number of Rapiers. @OP, I highly recommend watching this video to get a decent handle on how to build large planes: Once you can successfully get a large plane like this to orbit with the engine ratios mentioned in the video, then you can work on extending its range to the Mun (just think of the nervs and extra fuel needed as payload that you need to get to LKO first)

They will still produce drag. To prevent or reduce the amount of drag they produce you have two main options: 1. Put them in a cargo bay or fairing. 2. Use node attachment on any open nodes to reduce their exposed surface area, as detailed in this video:

Even aside from that setting, you can level up a Kerbal via the mobile processing lab.

To see the exact amount of drag each part is producing, and the total drag the crat is producing overall, you can enable a couple of options in the debug menu. Alt-F12 -> Physics -> Aero -> Check "Show Aero GUI" and "Aero Debug Data in Part Action Menus" Drag in KSP is calculated based on the surface area and shape of parts.... kind of. When you node attach parts, the game reduces the surface area of the face the node matches with but the surface area of the corresponding face of the attached part (so node attaching a 1.25m fuel tank on the front of a 2.5m tank reduces the front face area of the 2.5m tanks by 25%, and completely eliminates the rear face area of the 1.25m tank) If a part isn't node attached it is considered fully exposed to the airstream, unless it is in a fairing/bay. This is what is happening with the radial attachment points. This means they are creating a lot more drag than the engine plate would (since the engine plate is using node attachment) For more info on how the drag calcs work, check out this video: