DerekL1963

Thanks!

Which is good information, but doesn't have the same functions as Marcelo's. (And I lack the math/spreadsheet skills to create one.)

If possible, could you make a Google Sheets version? Not everyone has Excel.

@DDE That quote fails to support your claim. ("After a single TMI a nuclear-thermal engine is burned out".) One full day of full power operation is between four to six round trips to Mars. Nor does it support your assertion that designs in the 60's used "multiple NERVA stages".

But risks having Ike wander by and try to join in the fun.

Yep. In the various plans to use lasers for missile defense the damage mechanism (contrary to what people think) isn't "melt the target" or "drill a hole through it" - it's "induce shock by instantaneously vaporizing a portion of the target's skin". A friend of mine who worked on one or another of the many laser projects the DoD was pursuing back in the 90's likened the effects to taping a hand grenade to the surface of the target and setting it off.

The sound you heard was my point whooshing over your head - 3D printing is getting cheaper and more capable almost by the day. Your presumption that since "melting is involved" 3D printing is suspect is off base. (If for no other reason than melting underlies all metal forming processes - even conventionally machined engine parts.)

You're furiously ignoring a lot of things - like the existence of major components and even flown engines using significant amounts of 3D printing. SpaceX is also flying 3d printed hardware. Lawrence Livermore has produced a prototype engine, regeneratively cooled, with no welding. Why wouldn't it be possible?

Nothing I suppose, I just like attachment points for consistency and repeatability. Larger "indents" would make for a smoother mold line by recessing the docking port. Figured it never hurts to ask.

- Some kind of small truss for solar array backbones. (The small parts in NFC have three-way symmetry, while some multiple of two is the most useful for solar arrays.) - Some form of cargo/payload bay where stock or third part parts (life support, science equipment, tankage, whatever) can be hidden away. (I use stock payload bays ATM, but they're UGLY.) - Something like the 2.5m crew tubes, but with the "insets" (where the windows are now) large enough and with an attachment point for a Clamp-o-Tron. (Let us build our own docking or node modules without the part cost of a radial attachment point.) The larger of the two large enough to dock two 2.5m craft side-by-side with clearance. (4 meters apart?) Two way would be great, four way *outstanding*. An alternative would be to just provide attachment points at the existing windows. (Two way or four way.) Thanks!

In theory. In practice, what components have been tested have only been tested at the crudest, most primitive, proof-of-concept level.

54 come November... And ayup, still roleplay.

Yup, it's not just minimizing direct costs... It's also minimizing overhead and then amortizing that overhead across a large number of flights per vehicle - not just total lifetime flights, but also keeping the daily tempo maximized so that any given aircraft spends as little time on the ground not earning money as possible. That is the real barrier to low cost reusable launches, reaching and maintaining that high tempo. And that high tempo brings safety and reliability issues the space industry hasn't even begun to think about addressing. If airliners were as unsafe as rockets, Sea-Tac alone would have a crash on takeoff one of two times a day. Seriously, what the space industry accepts as business as usual in terms of accidents and loss would be considered horribly unsafe by any other standard.

Fuel has never been the cost driver in the first place... So, no offense, this is a totally useless metric.

Thanks folks, time to start digging into individual mods!

[x] Science is cool (and in use), but thought I saw one with a more compact display based on the instruments onboard the vehicle.

Working on my planned science mode campaign game still... Ended up moving both the HG-5 and the DTS-M1 down into the start node, vastly increasing my choices in climbing the tree. I'm also handicapping myself by only using the Universal Storage versions of Dmagic's instruments, as they typically appear a node higher in the tree. I think I've got a handle on it now, the early stage is so important... With setup for the County Fair starting this weekend, and then the County Fair itself (I volunteer as a docent for the Photography display and assist with the Photography competition), plus my anime stuff... I don't know when I'm going to be able to start though.

Dang, there are so many mods, so hard to keep track... Anyhow, I'm pretty sure I saw a mod the other day that would alert you to science being available (but does not auto perform experiments). Am I crazy or does anyone know of such a mod?

Not even close to the only one. Welcome to the club!

I don't judge first stage performance by time or altitude - but by Ap at burnout. (We're not trying to spend time or gain altitude after all, we're trying to gain velocity.) Generally I'm looking for at least 20-30km for conventional designs, rather lower for the first pair of asparagus stages in a cluster design. If I can't hit that, generally I'm not going to space today.

If your design is a modification of the existing design - that means you're importing the flaws and problems of that design into your design. That opens them up for discussion. (Not to mention it's not up to you to limit what other people discuss. If you don't don't want to discuss those things, don't reply to messages on those things.)

Actually last night, because it's too late and I'm too tired to write things up when I'm done... Made a quick run through (no roleplay, etc...) of a Science mode game, testing the proposed settings. Basically 50% Science return balanced by having Dmagic's science pack installed. While it was doable, it wasn't very fun. I spent a lot of time scrabbling around for every scrap of Science... when I was trying to avoid the grind to start with. I'm trying to find a sweet spot between the grind and the flood of Science that Dmagic's mod provides. I already use a MM script to move stuff into the Start node (as shown below)... Basically this provides roughly the same starting capabilities the US has in 1959 - and so I don't have to go through the grind of strip-mining KSC for Science or resort to craft designed by Rube Goldberg. I see two options at this point. First, turn up Science return. Second, move the DTS-M1 down in the tree so I can go interplanetary much earlier. (Grinding towards the DTS-M1 is the primary source of my dislike of my initial test.) I think the second option may be the way to go, combined with possibly turning the Science return down a touch more (to compensate for the flood provided by interplanetary Science). (Ignore the orange tank, it got moved down while I was testing the script and doesn't get moved in the production version. I'm too lazy to go back and take/edit a new screenshot.)

Relative ease of fuel acquisition? There's no supplier (at least not in the US) that will provide HTP in small quantities to non professional organizations (read: folks who aren't schools or governmental bodies.) This means brewing your own. Compare with LOX, which can be had with a phone call. Higher reusability? Not as much as you think - cat packs are difficult to re-use because of problems with catalyst poisoning and stripping. (One downside of concentrating down your own HTP from commercial grade? It concentrates the stabilizers too - and they're almost always catalyst poisons. This further compounds your acquisition problems.) And that's setting aside the problems of designing a cat pack in the first place - even one without the novel configuration required by this engine. Not to mention that, AIUI, cat packs are fairly expensive. And seriously, unless you're launching a dozen of these on a regular basis, reusability shouldn't even be something that figures into your planning. Reusability is cool, and hip, and hot... But it also imposes costs, and those costs have the be balanced by payback. I've said it before, but it bears repeating - lowering costs isn't just an exercise in engineering, it's an exercise in beancounting too. From what I read it's not, people build regeneratively cooled engines regularly. (And it's getting even easier as 3D printing improves and you're no longer limited by what can be machined by conventional means.) Agreed. If you're on an amatuer budget, it seems like a good idea to spend your money on development (that is, coloring within the lines of what is known) rather than research (going outside the lines into the unknown). Development of a conventional motor is going to be difficult and costly enough, researching and developing a complex new motor just cubes that. (And to make things worse, the new motor is an evolutionary dead end, so it doesn't even make a good training ground.)

Hold on a second yourself. I can't figure out how you could reach such a conclusion yourself. All I did was supplement your quote (which indicated that the the author found said engines to be problematic) with other information (which shows that they can be made to work).

McJeb McRocketface?