Ultimate Steve

Correct, there are some hard limits we can use to estimate... Assuming the Raptor is still the 2000kN one quoted on Wikipedia, that means the mass is capped at 600 tons. Not very helpful... But the FCC filing asked for, what, 5 minutes and 5km max? That's 5*60 = 300 seconds at ~10m/s^2, so a maximum 3 kilometers per second of Delta V is required, ish, using 330s for sea level Raptors, which might have changed, which would require the mass to be 40% structure and 60% fuel. However, I doubt that this hopper has that much Delta-V, the header tanks don't need to be that big. I don't think we have up to date dry mass numbers for Starship since the stainless steel update, let alone for the hopper, all we have is an old 85t estimate, and I'll roll with 100t to make the math easy and to account for the idea that they might build the walls thicker because they don't need this to be a high quality vehicle (it might be even higher still!). That means 150t of propellant for a 100 ton vehicle for 3 kilometers per second. The operational BFR is supposed to have around 1100 tons of propellant (last official number, probably pre-stainless), so that's a bit over 15% of the total Starship fuel mass. And the header tanks only need a few hundred meters per second of Delta-V for landing, but... At least in the 2017 version it looks like the header tanks take up 1/14-ish of the volume. That's ~7% of the fuel, not 14%, meaning probably one of the following: Starhopper has full fuel tanks (doubtful given those welds) Starhopper has larger than normal header tanks for testing, a custom tank (this involves differing from the production design but it could be likely) The overall design has been changed for larger header tanks (doubtful, I don't see a place where you'd ever need 3 kilometers per second of Delta-V sitting around, although with a 150t payload that would only be 2.2km/s. Landing only requires a few hundred meters per second, unless you want to do a pre-entry burn or an entry burn. Or my favorite and the most probable IMO: The application for the flight tests anticipates also hop testing with a production or at least near-production vehicle, the hopper can't go do that much. ...And this fits well with the application... I've been using the high altitude numbers this whole time, and the application also specifies parameters for low altitude tests - 500 meters and 100 seconds. 100 seconds at 10m/s^2 means 1km/s of Delta-V. That only requires the vehicle to carry ~40 tons of fuel based on 330s sea level isp and a 100 ton dry mass. 40 tons fits into our 7% number for the header tanks, which is about 77 tons assuming that it's actually 1/14, and looking at the (admittedly old) diagram it looks to be a bit less because of rounded edges. TL;DR: Starhopper has approximately 1 kilometer per second of Delta V, probably a bit more, and probably only has header tanks installed rather than a cryogen-tight skin tank. This also means that the thing only has a takeoff mass of ~140 tons, maybe more, meaning it doesn't need three Raptors. It could get away with one. But who knows, maybe they are testing different landing profiles, need roll control, will add dozens of tons of ballast to the hopper, or maybe all three.

Someone who has more free time than me should take the quoted thrust of the Raptors, the estimated mass of stainless steel in the visible configuration, and look at what kind of dV the existing hopper can expect to achieve. There's a few problems. We don't know how thick the stainless steel is, how much else is inside the rocket, and how big the fuel tanks will be. I'm pretty sure that the main body is not cryogen-tight and they will only have small tanks inside the hopper for tests, but I'd like to be wrong.

Just one more stacking! Unless they have internal work to do or decide to make it even huger...

Ah, I forgot about the whole "loading" part. Is muzzle loading artillery a thing?

You could use fairings and make them smaller than 1.25m by shaping them manually. The only downside I can see is that you'd have an awkward conic barrel at either end, on the gun end it would end in the fairing and on the air end it would have to end going outwards into another hollow part, such as a decoupler or a structural fuselage.

It's only 3 days into 2019 and we've had all this!

I've done Mun, Minmus, Eeloo, and most of Duna/Ike. I still need to do Moho, Eve, Dres, and Jool.

EDIT ignore this

I see squiggles!

Hmm...

Hmm... Interesting theory on the gimbal. I'm still leaning towards mockups, as Elon tweeted that the redesigned raptor would not fire until January. It seems a bit early to see the New Raptors, unless they are sticking the old design on just to say they can fly, or as a test, which doesn't make much sense. Although they still could be real, for all we know... A few weeks ago we all thought this thing was a water tower. As far as the dual bells, maybe the engine goes farther upwards and there is a hollow space. Although it could be structure. But then that raises the question of why the hopper would need vacuum Raptors... But, yeah, I'm leaning towards shielding as the bell diameter appears to be 1.3-1.4m, which is the old statistic for the SL Raptor.

Oh. That almost makes sense. Thanks!

But then it wouldn't be single stage!

Weelllllll, not quite. Yes, at very high fractions of c, there are time dilation effects... but there's also distance contraction. From the perspective of someone on the ship, you do not appear to be going FTL. Instead, you appear to be going the exact same speed that a "stationary" observer would see-- but to you, the distance you travel appears shorter. So, let's suppose that you take a trip on a spacecraft at 0.994987 c, i.e. about 99.5% the speed of light. At that speed, the Lorentz factor (i.e. amount of dilation) is 10. Let's suppose you take a trip over a distance of 1 light year as measured by a "stationary" observer back home on Earth. What does an Earth-based observer see, versus what do you see? Earth-based observer: You're traveling at 0.994987 c. You take just a smidgeon over 1 year to travel one light-year's distance. Observer on the spacecraft: You're traveling at 0.994987 c. You take just a smidgeon over 1/10 of a year to travel 1/10 of a light-year's distance. The two observers agree on how fast the ship is traveling. They disagree about how far it went or how long it took. Okay, then. Dang, this is making my head spin... So they would both observe the spacecraft going 1 light year in 1 of their local years (time to distance traveled ratio remaining the same, so no magical speeding through time) but time is passing 10x faster for the guy on the ship relative to Earth time?

I may be very wrong, but IIRC you seem to be moving through time faster the faster you go, to the extent that if you were, for some reason, travelling at the speed of light, from your perspective any trip you took would be instantaneous. So if you got on a spaceship and reached 99.99% of the speed of light, from your perspective you would be going FTL because of this time dilation. From Earth's perspective you would not be going FTL.

Maybe if the BFH isn't blown up during testing they will make it into a water tower afterwards...

Found on NSF:

Another thing I forgot to specify, and the revert rule does make it seem like the revert is the only method, but really what I meant was that you need to revert when the choice is revert or rescue.  Quicksaves/quickloads are fine. Reverts are fine. You can quicksave and quickload any time you want, and revert any time you want. The only rule is, if your mission becomes impossible to correct without quickloading (say, you realize you really don't have enough fuel to get home no matter how miserly you are on the way there) then you can't sent up a rescue or refueling mission. you must at that point revert, fix the problem, and relaunch. Just time warping through atmosphere, or even crashing on a landing because you hit X instead of Z at that last crucial moment, is fine to correct with a quickload. Ah, okay, I can reduce my stress level by a factor of 5 now! I was really dreading trying to do Eve without saving!

@5thHorseman If a glitch happens... Say if you accidentally warp past something, say, warp through Kerbin's atmosphere at the end of a long Eeloo mission (something that shouldn't really happen, phasing through things), could one quickload to just before that happened or would one have to redo the entire mission?

I'm assuming no science labs are allowed, right? I may make an attempt. I'm gonna go get 1.6 finally... EDIT: Nevermind, I don't want to get all the informational mods ready, 1.4.5 it is... That's fine, right? Edit 2: There are many mods installed but they are all informational or visual, aside from HyperEdit and VesselMover which I will not be using for this challenge, obviously.

I don't mean to insult ISRO's professionalism (I am rooting for them heavily) but one of the diagrams from that article (not sure if it is directly from ISRO or not) looks like something I would have thrown together for a 5th grade project: But, hey, maybe that's them spending money on the actual spaceship rather than fancy graphic design!

Ah, oops. I'll do that now. Moar sooner than later, as the screenshots for at least most of the next chapter are done, as they were supposed to be lumped in with this chapter, but it got really long (7k plus words).

Ultimate Steve - April 1956 (Cycle 22) (We're slowing down for dramatic effect) Notebook Space Program: The Science Module is FINALLY launched! @qzgy You're up!

Before the Parker Solar Probe launched, NASA had a site where you could submit your name to be recorded on a small memory card, which would be attached to the probe. It's probably been fried and bit-flipped to the point of it being unrecognizable now, but my name is up there, touching the sun, flying past Venus... It may be the closest I ever get to going to space, although I hope not. My grandfather's name is also up there. He worked at NASA Lewis for 30 years.

So far! Although depending on your viewpoint it could be argued... But I think that launch definitely affected the public more than any other launch. As for my top 3... How does one judge? Three were so many great ones, so many important ones, etc. Definitely up there is Falcon Heavy, Parker Solar Probe (my name's on it!), InSight, MS-10... There's too many to rank!