wilt57

I didn't watch all your videos, but your ascent profile was much better on that last video. Keep trying to stay within the prograde marker until around 15-25k or so. Try to time it so that your prograde marker is around 45 degrees in the 10-15k range. These are all general though, different TWRs will warrant different ascent profiles. It's your game and I don't want you to play with rockets you don't enjoy building or flying, but you are still bringing too much engine at launch, at least at the beginning of your last video, which was a far as I watched. I aim for an off-the-pad TWR of 1.2 using atmo thrust. This way you shouldn't have to lower your throttle so much. By the time your thrust increases with altitude and fuel burn-off, you should be able to maintain a decent TWR without going too fast. Not only are you spending funds on rather expensive-ish engines, you are burning excess fuel to accelerate their mass. Reaching terminal velocity ASAP isn't as big a deal as many players make it out to be.

I'd say it's an exploit as far as using an inexhaustible amount of fuel. Using EVA packs to orbit/deorbit? No. That's using the game's physics. If you could do that on any body, then it'd be an exploit too, but it takes TWR and Dv into account (at least the amount of Dv a Kerbal can take with them) so it's not cheating. However, good for you that you can eyeball rendezvous with EVA and can get 2100-some science off your first launch!

I voted use them a lot, but only one at a time. Except going to Minmus, I put out a second one at the AN/DN to see if my original node was placed correctly. I'm not to the point of IP travel in my career yet, but I imagine using a second one to deal with inclination to make sure my first one has been placed right too. I don't set up a series of them to plan out my Dv, I use a Dv chart to do that. However, I don't use them ALL the time. I'll eyeball my maneuver to place my PE right where I want it after a SoI change. I eyeball many inclination changes too, but I like to put a node down if I'm going to use any radial burns for corrections. I also put a node down for circularization burns because I don't fly with a standard ship. My acceleration values vary enough where I like to put a node down mainly for getting the correct burn times. I've been trying to learn to use them better for timing landing burns. Haven't nailed it perfectly yet, but they definitely help getting much closer. I think they are a very important part of the game. I can appreciate those who do not need them, but I pretty much do need them and I think it can reduce small amount of Dv usage vs. not using them.

When aerobraking, you are under an acceleration. A negative acceleration produced from the drag of the atmo. As sal_vager said, use alt+ to use physics warp. It's only x2, x3, and x4, but it's better than nothing.

Most likely you just overshot it by a bit. I'm pretty sure MJ's new warp helper has a phase angle mode now, but I haven't used it yet so I cannot comment on its accuracy. Otherwise Otis has a good suggestion. I mainly use Kerbal Alarm Clock. I cannot remember exactly right now because I haven't done any interplanetary stuff in a while, but there are two modes to calculate transfer times. I think MJ uses one mode for inward travel and the other for outward. I wish I could log on right now and check to help out more, but I can't.

This. It always takes more delta-v to get to a higher orbit, so it'll always take more delta-v to come back down from that orbit. Also, due to Oberth's you will get more delta-v per unit of reaction mass burned in the lower orbit. In many cases this won't be very much, maybe even unaccountable, but the math is still there.

Just wanted to clarify something here. Ferram does not allow you to fly faster than terminal velocity. You can always fly faster than terminal velocity, if you want to. Ferram does not allow you to save delta-v by flying faster than terminal velocity, it allows your terminal velocity to be faster. You still want to fly at terminal velocity, it's just that Ferram allows you to have a faster terminal velocity. Why? What is terminal velocity? Very quickly, it's when the force of drag equals the force of gravity. If your rocket is more aerodynamic, it's drag generated is less, so it's terminal velocity is higher as gravity remains constant. We want to fly at terminal velocity because at that speed the sum of our losses to gravity and our losses to drag is the least. Any faster and we generate more losses to drag than we're saving to gravity. Any slower and we're losing more to gravity than we're saving to drag. It's all about balancing the losses we generate. As we know, it basically takes 4,500 delta-v to reach LKO. At 80 km, my ship is only traveling 2,279 m/s. The missing 2,221 m/s went into drag, gravity, and a little bit of steering losses. It's managing these losses that's the goal of an efficient launch.

This matters where you're at. If you have already achieved orbit, 4000 delta-v is 4000 delta-v. Both rockets will be able to get to the same places, assuming you don't have too long of a burn with the .75 TWR rocket. It's different when considering landing or launching from a gravitational body. If your TWR local to the body you are trying to launch from is lower than 1, you will have to burn off reaction mass to lighten your ship before it lifts off. You have lost that available delta-v because you were not able to use that reaction mass to either increase or decrease your rocket's velocity. If your TWR is above 1 but still very low, you will incur excess gravity losses during your ascent. If your TWR is too high and you are launching from a body with an atmosphere, you will incur excess drag losses. In either case, you will incur both gravity and drag losses, the key is to minimize their sum. That occurs at terminal velocity. So to reduce the amount of delta-v lost during ascent, you need to match your TWR to a value that allows you to fly as close to terminal velocity as possible. This is at least important early in the launch, it is generally too cost prohibitive to maintain terminal velocity in the later stages of your launch when you are traveling through the thin upper atmosphere.

I agree SRBs will have a stronger future when costs come to play, but I don't think asparagus will be any type of false prophet. IMVHO, one should never include SRBs with the intention of adding delta-v to a rocket. The best use of SRBs is adding TWR to a rocket that has the delta-v to make orbit, but loses too much to gravity due to too low a TWR. Here, the SRBs are not adding delta-v, but recovering lost delta-v. Tweakables help here quite a bit, as I've always felt the current SRBs have too short a burn time. It's nice that an SRB comes with fuel and engine all in one part and thus helps lower part count, but if you are up against part count limitations, I don't think a 325 kN engine is going to give you the increase in thrust you need for that monster. Perhaps the inclusion of a 2.5m SRB would, but not the current 1.25m parts. This is all concerning the launch vehicle. Once in orbit things change quite a bit.

Cost is important, and SRBs are cheap, but it isn't important yet. I did some delta-v calculations. First, let's assume I have a 10 ton ship powered by an LV-T45. I do not have enough delta-v to complete my mission, so I add reaction mass to my orbital stage. For this specific scenario, I have two options: A) Add two Rockomax BACC Solid Fuel Boosters on TT-38K radial decouplers or, Add two liquid fuel and oxidizer boosters consisting of an FL-T800, an FL-T400, and an FL-T200 on TT-38Ks. They are cross fed to the base ship with fuel ducts. This is a nice comparison because both the BACC and the stack of FL-T tanks add up to 7.875 tons full. Using this delta-v equation: delta-v = ln(start mass / end mass) x Isp x 9.81, For option A I have a starting mass of 25.8 tons, an ending mass of 10.05 tons, and a vacuum Isp of 250. I add 1,671.6 m/s of delta-v to my base 10 ton ship using option A. For option B I have a starting mass of 25.9 tons, an ending mass of 11.9 tons, and a vacuum Isp of 370. I add 2,822.8 m/s of delta-v to my base 10 ton ship using option B. If I indeed did these calculations correct, I add more delta-v per ton of mass lifted to orbit by adding liquid fuel and oxidizer than I do solid rocket boosters. I don't have the numbers for the SRBs you used form KW, but the point I'm trying to make is adding more reaction mass for an efficient liquid fuel rocket will gain you more delta-v than adding that same reaction mass for inefficient solid rocket boosters. I hope I did the maths right! LOL

They are still thrust generating devices that spend reaction mass to add or subtract velocity from your ship. Even if you decide to not use them until you are already in orbit, they took the expenditure of reaction mass to lift them to that point. They are ever so much part of the ship. As for your Mun encounter, I don't see a PE tag on your orbit. Looks like a surface impact incoming. Glad you are reaching new milestones in your space program. Keep it up!

You have to remember to include the fuel burned to lift the re-fueling fuel from 80 km to 600 km. It's the cost of the entire space program, not just any individual ship.

Start out with a piece you will not use. That's your root part. Build your rover extending from that piece and then copy it to the sub-assembly. Just remember that you'll attach the sub-assembly from whatever part was attached to the root in the SPH to wherever you want to attach to your rocket in the VAB.

This is how I view it. I don't want to take the time to plan out ahead of time when to start my PE kicks and at what ejection angle to start so that I'm in the correct position by the time I make my last burn. What a pain in the butt. I'll lose a couple 100 m/s of delta-v to cut my burn times in half, or more. If my delta-v budget is really that close, adding fuel tanks to ships this size is not a very big concern anyway.

Exactly. It turns out that the 4,500 number is pretty spot-on for fuel efficient ascents. Remember OP, delta-v is not fuel usage, it's merely change in velocity. We can get to orbit by flying at terminal velocity as long as we can, and in doing so we can reduce our losses to gravity so much that we may be able to get to orbit using 4,300 delta-v. Maybe even less. Problem here, as EtherDragon has mentioned, is that we are carrying massive amounts of thrust high into the gravity well in order to keep up with the ever-increasing speed of terminal velocity. More thrust generally comes at the expense of more dead-engine mass, lower specific impulse, or a combination of both. These require us to pack more fuel to re-achieve our delta-v goal. By using less thrust and smaller, more efficient engines we are capable of getting a given tonnage of payload to orbit using less fuel, even though we "used" more delta-v. The trick is finding that middle zone that gives us enough TWR and delta-v while using the least tonnage in our lifter. Payload fraction is more important than delta-v usage. As payload mass is constant, the only way to increase payload fraction is to reduce lifter mass. The majority of lifter mass is fuel. Of course, that only matters when costs become important.