sevenperforce

Thanks so much! (For the next poor shmuck who can't see images, it's a Sun orbit w/ semimajor axis of 11500000000, eccentricity of 0.001, and inclination of 180.)

The OP is corrupted; does anyone know what the parameters are for Burbarry's orbit, using the Set Orbit function?

The rocket will be supersonic between 10 and 20 seconds after liftoff.

As I show in another mockup, the burn region will be much longer than shown. Also note that this is just the engine end; the whole rocket extends vertically quite a distance.

Backup chutes for aborts are fine, but propulsive-only landing is preferred.

Edited OP to allow constellation launch to polar orbit and revised 50% limit on LF tanks.

Oh, you certainly don't need to recover the second stage manually or reuse the same actual first stage; you just have to show that you landed it. You can reload from scratch in the VAB for each subsequent mission. If people are having trouble with the TSTO architecture, you can even save right after stage separation and simply fly the first-stage return by itself, then re-load the second stage and fly it separately. You do need to do all three launches separately, though; no single-launch approach.

Not quite sure what you're asking. The payload must decouple from the second stage once it reaches its intended orbit and the second stage must be recovered, just like the first stage must be recovered. But of course you can just use the "Recover" function and go back to the VAB and load the old vehicle when you go to the next payload. For example, I'm going to do a single-stick TSTO with the payload mounted on top of a heat shield on top of the second stage on top of the first stage. I'll launch to an apogee over 70 km, separate, switch to the first stage and do a boostback burn, switch back to the second stage and burn to orbit, then switch back to the first stage and do the entry, descent, and landing. Then I'll go back to the second stage, correct the orbit, decouple the payload, and then deorbit the second stage; going nose-first on the heat shield until the lower atmosphere and then flipping to land on the engine.

The throat will be much smaller than depicted and the "chamber" will have a longer characteristic length, permitting higher chamber pressure. Also, the HTP injector and catalyst bed should probably be conical and pointed outward.

Sure, I'll relax the KSC landing requirement for the second stage. You can put the second stage down anywhere on land, as long as it lands intact.

Same actual launcher; that's the critical element of this challenge. This concept comes from the idea that making a reusable launch vehicle profitable requires frequent reuse, which means that you can't have a different launch vehicle for each different contract. You need to be able to build and operate a single launch vehicle with enough capacity for the entire range of commercial launches. That's why I have three separate missions to represent the three types of launch contracts available to medium-lift launch providers today: commercial crew, LEO heavy comsat, and GTO medium comsat. Obviously the payload adapter will vary from launch to launch, but that's expected. This also shows one of the challenges faced by Skylon: it's not enough to get a single large payload to LEO; you need to be able to put payloads in GTO as well, and you need to be able to launch passengers safely. Skylon must develop a solid kick stage for GTO missions, since the whole launch vehicle cannot make it to GTO.

I didn't test this at length; I can change to 1/2 capacity if it will be too difficult to make orbit. I'm sure there are people here with more spaceplane experience than myself. On the opposite side, the rockets are going to need to reserve hella propellant for propulsive landings, so that's another consideration. Also, piloting a reusable TSTO to orbit requires separation outside of the atmosphere and a lot of careful switching back and forth.

One third of total liquid fuel capacity. So mixed LF/O tanks can have their oxidizer filled fully but can only have 1/3 of their liquid fuel capacity filled. If I was being completely fair it would be something like 1/5, given how fluffy liquid hydrogen is compared to kerosene, but I didn't want to make it too ridiculous.

Decreasing burn area decreases the available fuel flow, which decreases burn rate. Nozzle vs oxidizer injector geometry is not necessarily to scale.

True...but if you can manage to make a reusable vehicle, initial cost is not as important as refurbishment cost and operating cost, which scales loosely with vehicle dry weight. In addition, KSP's part costs aren't necessarily very useful; optimizing for dry mass rather than for cost is a much more interesting challenge.

Good questions! The trick with this particular plan is to have geometry such that the available burn surface area will decrease if the propellant flows/burns upward and increase if it flows/burns downward, providing negative feedback rather than a positive feedback loop. This can be achieved by making the base of the oxidizer tank and catalyst bed injector assembly an upward-opening cone, so that the cross-sectional area of the fuel "tank" decreases as you go up: As you can see, the surface area of the exposed fuel is greatest in the depicted geometry. Should that surface regress upward (either due to increased burn rate or increased chamber pressure), the available surface area will decrease, lowering combustion rate and chamber pressure. Recall as well that head pressure is not the only determining factor; the entire weight of the annular fuel column is pushing down on the chamber, and moreso under acceleration. This is why the hybrid likely would not be restartable; once flow begins, you need positive chamber pressure or the fuel column will creep out of the nozzle. During an active burn, the fluid dynamics will probably look something like this: But if it has the consistency of rubber it won't flow, so the whole pressure feed concept won't work. Eh, not necessarily. There is a complex interplay of possible fluid dynamics across a range of pressures and temperatures. Depending on the combination of gelling agents used, the napalm can be a shear-thinning fluid, a shear-thickening fluid, or a Maxwell fluid. It can flow in response to heat, thicken in response to pressure, or basically exhibit any other range of behaviors, all based on composition and chemistry.

Eh, I don't like it. Can I launch the mobile lab instead?

In the age of reuse, space agencies have a decision to make: TSTO rocket or SSTO spaceplane? Of course, until Skylon flies (if it ever does), TSTO rockets are the only game in town. But in Kerbal Space Program, spaceplanes fly with ease...which brings us to this challenge. Your mission, should you choose to accept it, is to build either an SSTO spaceplane or a TSTO rocket to carry commercial payloads into orbit over Kerbin. Every stage of your launch vehicle must be reusable, and you must use the exact same vehicle to launch each of the following three payloads: A 15-tonne survey satellite to polar orbit (150x150 km or higher). The survey sat must be fully functional. (ADDED OPTION: 15-tonne sat constellation in the same orbit) A 6-tonne relay comsat to Kerbostationary Transfer Orbit (75x2863.33 km or higher). The relay must be able to self-circularize into an equatorial KSO; the relay must be fully functional. A crew vehicle containing at least 7 kerbals to rendezvous with an equatorial space station (200x200 km or higher). The crew vehicle must have independent maneuvering capability and power generation, and must be recoverable. You do not actually have to have an equatorial space station, though if you do, awesome! The challenge is to build a launch vehicle with the lowest possible dry weight. Rules: General: All entries must use 100% stock parts. No piloting mods, though other mods are fine. Obviously, no infinite fuel or similar cheats. TSTO rocket: Both stages must be recovered and must land propulsively. The crew vehicle must have abort capabilities and must also land propulsively (chutes okay for backup; e.g., on abort). Payload fairings, assorted decouplers, and engine shrouds may be jettisoned without recovery. First-stage recovery must be reasonably close to KSC; second stage (and crew capsule) can be recovered wherever you want, as long as it comes down on land. Chemical fuel only (other than on payload). Vertical takeoff from the launch pad. SSTO spaceplane: Takeoff and landing must take place on the runway. Must launch and land with probe only; no crew (except for the crew-vehicle launch). No nukes, ions, or solids. Other than RAPIERs, the only rocket engines permitted are low-thrust OMS engines. All payloads must launch and deploy from inside a payload bay. The crew vehicle must be able to dock back inside the payload bay for re-entry. It does not need to have 0/0 abort or independent re-entry. An expendable solid kick stage is permitted for KTO injection of the relay comsat. To reflect that Skylon will need to carry liquid hydrogen for its precooler to work, LF tanks may not be more than 50% full at launch. Oxidizer tanks may be filled completely. This is a community challenge, so here's how it works. You can submit either a TSTO rocket, an SSTO spaceplane, or both. There will be a leaderboard for lowest-dry-weight rocket and lowest-dry-weight spaceplane, but the overall competition will be between rockets and spaceplanes. The winning leaderboard will have the lowest total mass from the three leading entries. Good luck!

@Bottle Rocketeer 500 Here's Exploration Mission 3: As far as EM-4 is concerned, I'm a little lost. You don't really give much information about any of these launches; there are almost no requirements to meet. What should the Logistics module be? A mobile processing lab? Radiators? A lab with a probe core and some RCS thrusters? Comms? Science instruments? A cupola so it can be piloted in to dock? Ya gotta give me something to work with.

Here's Exploration Mission 3! First all-female crewed launch! SSME ignition. Up, up, and away! My TWR is really through the roof. Disaster!!!! Because of a lighter-weight payload, I was going VERY fast very low in the atmosphere at stage separation, and so one of the SRBs impacted the core. Big explosion. Samlenna and Maxsie are horrified, as expected. LES successful, though! I had the LES set to jettison the heat shield on separation, to help with TWR. This...might not have been a good idea. Will it work? I popped a single drogue to try and prevent excess heating...thankfully, I made it. None the worse for wear! Trying again. Liftoff! This time I'm turning 90 degrees so staging doesn't RUD me. Quick gravity turn. Moment of truth! Ahhh, much better. LES jettison. Staging! Very small circularization burn. Decided to follow the core back down to see if it survives re-entry. Toasty! Surprisingly, it did survive re-entry...though it obviously didn't survive impact. To match the weird polar orbit, I'm going to have to make the injection burn rather tricky. Finishing the injection burn. Executing the flip. Docked and separated from the EUS! The EUS will follow a nice slingshot out of Kerbin's SOI. The crew can see Kerbin below and the Hab module out the front window. After some adjustments, coming in nicely. Panels out, testing systems. This is a weird orbit to try and match from TMI. Here goes! Love the radiative nozzle. Almost done with orbital injection. Captured! Now to rendezvous. Got the first intercept to match. Burning to match velocity. Going to do the final approach and docking with the PPM to conserve propellant. Closing. Target locked! Kerbin in background, and... Docked! Our fledging space station doth ever expand. Touring the hab. A quick spacewalk just to check out the systems... Looks good from here! Undocked, backing away. Burning for home. Fuel will be tight. Made it! Preparing to jettison the SM. Nice shot! Goodbye SM; hello Kerbin. Toasty. Unfortunately, not toasty enough; we skipped out of the atmosphere and had to do another go-around. Coming in again. Burned off a LOT of ablator. Made it! Heat shield jettison. Safely down!

We can set the net thrust wherever we want it on the kick motor. White Lightning is not pre-cast, so we can make it lower-thrust. The vehicle is fully suborbital by final staging, so there's no gravity drag loss from using a lower TWR. As far as refueling and reuse is concerned, I anticipate an interstage (with recovery and guidance hardware) that bolts over the top of the fuel column. So you basically just take the lid off, pour in the napalm (using some sort of insertable mold at the base to ensure the burn area is correct), and then replace the lid. Unless there are some overly generous assumptions I missed somewhere, I think my spreadsheet demonstrates that we can easily reach orbit with a single-stick core, if we're comfortable going to a 10-12" core instead of an 8" one like HEROS-3.

I just used an action group to cut the drogues. EDIT: Oh, wait, did you mean docking port? I never decouple the docking port; I use the docking port as the decoupler for the LES.

I've got one better!

Done in pursuit of Doing It Orion Style: My three intrepid explorers, preparing for the first crewed launch of the glorious SLS! Pad view. Since this is the first crewed test, I'm starting with a little pad abort... All clear so far... Fairing and LES jettison. Drogues out... Popped the mains. Success! Reverted to the pad. SSME ignition! SRBs ignited; up, up and away. Nearing Max-Q, and... Whoops, aborting again! Couldn't resist doing a max-Q abort. Dropping nicely. Nominal splashdown. All right, for real this time. Majestic to be sure! Quite a clip. Heating up and leaning over. SRB jettison! High enough now to get rid of the LES. If you look closely, you'll see that I used a three-segment fairing. Burning very gingerly now. As usual, the SLS can make LKO easily on the core. EUS separation and ignition! Fairing jettison. Only a tiny burn to get up into LKO. Circularized! Orion's SM has solar array deployment. Now, here's where it gets messy. The current NASA plan calls for the EUS to place the entire stack -- DSG component & Orion + SM -- in a high Earth orbit with a period of approximately 24 hours. After this orbit, Orion will separate from the stack and enter its own free-return trajectory, while the EUS places the DSG component in a lunar flyby. I had to plot a couple of orbits ahead to get the timing right. Burning to raise Ap. Done! You can see that the second node appears, after this orbit. Set up for a free-return. Hanging out at apoapse! Orion separates on the way back in. Lost the old maneuvering node, but that's okay. Putting Orion where it needs to go. Extending solar arrays on the Power & Propulsion Module as I swing around the dark side of Kerbin. Setting up the escape-trajectory flyby for EUS disposal. First clear shot of the Deep Space Gateway Power & Propulsion module. Note docking port for refueling, hexagonal probe core, and "airlock" up top for experiment storage, as desired. Orion flying free with the EUS in the background. Finally back at Pe, and burning for the flyby! Switched over to Orion; burning for the free-return. Free-return complete! Separation from the EUS. The EUS will continue to a munar flyby and escape. Testing the engines on the DSG. In reality, the four smaller ion engines will be on special gimbal arms, but KSP doesn't have that capability. Here's what the current disposal trajectory looks like. Firming up the flyby. In reality, the DSG will be assembled in a halo orbit around L2, but since there are no Lagrange points in KSP, a polar Mun orbit will have to do. The Kermans are excited for their flyby! Setting up my node for munar capture. Thanks to the scaled-up ion thruster, I can do the capture burn easily. Orion is inside the Mun's SOI. Nearing Munar Pe; starting to throttle up. Full capture burn! Capture complete. Closest approach on free return. Goodbye, Mun! Set up a node to fix inclination. Inclination fixed! Getting ready to lower Munar Pe. What a beautiful shot! Reached my terminal orbit. Meanwhile, Orion is coming back in toward Kerbin. Service Module jettison. Starting to get entry heating; SM visible in the background. Took quite a long time, really. Through re-entry; drogues popped. Jettisoned heatshield. Mains popped, drogues cut! Splashdown! That's a wrap.

No problem! Anyway, I did the EM-2 as planned by NASA. Orion on top of the DSG component, inside a fairing on top of the EUS. Launch to LKO, then one preliminary burn with the EUS to raise Ap to supersynchronous orbit. After the first supersynch orbit, the Orion and Service Module separate and burn the SM engine at Pe to enter a free-return, while the EUS sends the DSG component on a munar flyby escape trajectory. After insertion, the two separate; the EUS rockets out of Kerbin's SOI while the DSG component does a hard insertion burn on its ions at munar Pe for capture. I don't much like the polar orbit, given that the purpose of the halo orbit for the real DSG is to be easy to reach from Earth, but oh well.