GoSlash27

Actually, I concur with this. If the comparison is meant to illustrate aerodynamic effects, you really can't get an accurate reading if differences in mass (non-aerodynamic differences) are clouding the results. Also, it matters whether we're talking subsonic speeds or supersonic speeds since the "side" flow decreases dramatically in this region. Going back to the tail cone vs. shock cone, the shock cone has less drag at subsonic speeds while the tail cone has less drag at supersonic speeds. How well they will perform in a test like this depends on how fast the rocket is going when it flames out. I ran into this problem this week myself. I had built 2 different test rigs to compare these parts and found the shock cone had less drag (which I didn't expect from the math). After checking out RICs results and reengineering the rig to hit ludicrous speed, the tail cone was superior. Best, -Slashy

for 1.5t payload to Duna? Lemme see... Assuming you want a low tech solution, you're looking at a 20t launcher so you'll need a pad upgrade. Stage 1 (boost) 2 LV-T30s with 2 stacks of FL-T800+FL-T200 or 3 Mk.55s with 2 FL-T800s and 1 FL-T400 or a Skipper, 1 X200-16 and 1 X200-8 Stage 2 (orbit) LV-909, an FL-T400 and an FL-T200 Stage 3 (Duna) 48-7S and an FL-T200 Best, -Slashy

^ What Val said, except it's drag per cumulative lift rating. One wing panel with a lift rating of 8 units will behave just like 2 panels of 4 units each and so on AFA lift and drag are concerned. KSP doesn't care if they're wet wings or simple panels. The only difference is the weight, and that is negligible at the scale of the total spaceplane mass they're lifting. I try to keep the total number of panels down in order to avoid structural weakness. Having floppy wings means you'll need to strut them, which adds drag. I try to keep the total lift rating within a range suitable for the mass of the spaceplane. Best, -Slashy

Gooru, Clearly it's going too fast too low. Best, -Slashy

Stoney3k, It depends on how big the spaceplane is. It turns out that all wings are equally draggy, so the important thing is to use enough wing area for the job. I do use wings to carry fuel whenever possible just to cut down on the spaceplane's length. Best, -Slashy

Rbenard, No, you don't *have* to use math to do it. The math just makes it easier. You want to have a good engine for the job. Pick one with good thrust and Isp for the boost stage. If you want to 2-stage it, then the upper stage needs an engine with good vacuum Isp for best results. You want at least 1.4G acceleration off the pad and at least .5G up high in the second stage. If it's too weak you need moar boosters or less payload If it runs out of steam too early you need moar fuel or less payload. It's a balancing act and a learning curve when you're just starting out. There's a nearly infinite number of combination of parts that will make orbit and also an infinite combination of parts that won't. You'll get a feel for what works and what doesn't as you experiment. You also need to have a good launch profile, which is a gravity turn. Check this guy out for a demonstration of a good gravity turn: http://wikisend.com/download/426314/SRBLifter.craft Just spawn it and hit "space". The first stage will follow a near- perfect gravity turn trajectory without any control from you. It will flip shortly after staging (the second stage requires some active control), but the first stage will give you a good idea of what a gravity turn looks like. Best, -Slashy

Just Jim, There's a best launch profile for each individual spaceplane, but no single "best" profile for all spaceplanes. You basically want to 1) exceed Mach 1.1 as efficiently as you can 2) Accelerate and climb to 17km as efficiently as you can and then 3) get as much speed as you can while climbing shallowly. For a spaceplane like yours you probably want to exceed Mach 1 around 8 km or so. The key is to maintain the prograde vector dead ahead for the entire atmospheric flight without losing speed. This yields the lowest drag. You'll have to experiment. Best, -Slashy

RIC, Thanks, I'll do that! Best, -Slashy

^ Correction: 9.81 is not the local surface gravity, but rather a universal conversion factor. It's 9.81 for every body. But yeah... incomplete thought is neither coherent nor communicable Best, -Slashy

Chaos Klaus, I'm sure you're right, but in my defense I *did* say the same thing you did. Nearly verbatim I just said it mathematically whereas you said it in English. But your form is definitely preferable for beginners to grasp, so thanks! Best, -Slashy - - - Updated - - - Xyphos, "Rwd" is just a placeholder. It stands for "wet/dry ratio". For our purposes we could use any arbitrary symbol to represent it. The first equation is the rocket equation written backwards. It basically says "If you start with the Isp of a given engine, then following this equation will tell you the ratio of your wet mass to dry mass that is required to achieve orbit around Kerbin." The second equation is an expression of the makeup of a single stage rocket. The only input required is the previously computed "Rwd". Following this equation, plugging in your engine mass and desired payload will yield "you need this mass of loaded tanks". It will only work, however, if the engine in question doesn't choke on the surface and actually has enough thrust to lift the entire stack at 1.4G or so. I tried to avoid the need to use definitions by using the definitions themselves as the variables. Apologies; I was in a hurry when I wrote it Heck, it might not even be correct. I didn't take the time to verify it... In plain direct language... what Chaos Klaus said. If you have an acceptably efficient and powerful engine, a small enough payload, and enough fuel... you will make orbit so long as you fly it right. Also, lots of helpful people on this forum who can help show the way. Best, -Slashy

JustJim, Congrats! Best, -Slashy

Gooru, There's a lot of things that could make that happen. We'd need to see a pic of your spaceplane. Preferably in the hangar with the CoM and CoL showing. Best, -Slashy

Gooru, You usually have to move the wings forward a bit after increasing the incidence to keep your balance. Best, -Slashy

RBenard, I recommend learning and using the rocket equation. It makes all of this a ton easier. Rwd= 2.718^[3,500/(9.81Isp)] 9(Rwd-1)(engine mass+payload mass) _______________________________ = loaded tank mass (9-Rwd) If you have a small enough payload, enough fuel, and an engine that doesn't suck you will make orbit. Best, -Slashy Best, -Slashy

NathanKell, As a matter of fact, I wasn't; I hadn't noticed that. But after checking the drag box in the .cfg, they're the same for the "Pointy end forward" values. Best, -Slashy

Possibly, but it's not outperforming it in my tests. I tried both balance beaming and vertical ascent at high acceleration (both with compensation for the mass difference) and the shock cone outperforms the tail connecter in both. Best, -Slashy

Apologies, I misspoke (mistyped?) I meant the shock cone. On paper, the tail connecter should be better. Best, -Slashy

Okay, so I've been through this thread and picked up a lot, but I'm seeing something that seems to defy expectation: For some reason the shock cone seems to exhibit less drag than the Tail Connector A. Type/area/Cd/Depth Tail Conn/1.21/.132/4.68 Shock Cone/1.21/.300/1.18 Surf. drag mult @ M1= 0.0025 Any ideas on why my empirical results aren't matching the prediction? Thanks, -Slashy

Claw, I've been through the whole thing (good stuff) but I'm afraid it doesn't explain what I'm seeing. I'll carry it on over there. Thanks, -Slashy

Claw, Aye aye Thanks, -Slashy

I generally enter prograde because it saves me a little DV for landing, orbit, and escape. But often for bodies that are tidally- locked I will enter polar so I can hit all of the biomes. Best, -Slashy

Honestly, I just run the default progression with no mods. That way I'm able to share the tips and tricks I come up with to unlock everything without grinding. Best, -Slashy

haha you're too young to be this crotchety ya whippersnapper! Why... back in my day we just puzzled out the changes and made it work! We went to orbit uphill both ways and we were thankful for what we had! / SSTO spaceplanes still beat the pants off of shuttles // made both /// get offa mah lawn Best, -Slashy

Okay, so as I'm digging through the drag box numbers, I'm noticing something odd: The tail cone has a much lower drag coefficient than the ram air intake and they have the same frontal area, yet the ram air intake exhibits less drag in testing. Anyone know what's up with this? Thanks, -Slashy

SpacedCowboy, I just learned today how to decode all of the numbers. Here's the important part: State Area/ Drag coefficient Retracted Forward 0.140/0.498 Retracted Backward 0.140/0.412 Deployed Forward 0.355/0.704 Deployed Backward 0.355/0.654 Best, -Slashy