Space Shaft Space Elevator, "Inflatable Space Elevator"

An airship could loft a rocket in the same manner as an airplane. However with a very big airship like a Walrus, it could loft a much bigger rocket than an airplane. I would imagine a hybrid airship would probably be able to loft a very big rocket. Imagine something like an Aeroscroft airship launching rockets into space.

This is interesting. It describes how an airship launch could be potentially cheaper than an airplane launch. This is different than a balloon.

https://dspace.lib.cranfield.ac.uk/bitstrea...e_Launch%20.pdf

Considering that B-52s and Trijets are used for rocket launches, you need a fairly large airship to get mass-competitive. Also, -52s and Tristars and such are cheap, this airship has to be a newbuild. Tbh, I wouldn't bother with pissing money away like that when there are perfectly good platforms already in use or available for conversion that let you launch about as big as you're going to get with any sort of aerial vehicle.

This is the point where I point to the fact that there's a reason Orbital does what it does, and it's not because they don't like to turn a profit. (Pegasus is stupidly profitable)




Oh, and it's not hugely different from a balloon, airships have all sorts of problems that we haven't even gotten into yet just inherent in their operation, slaving your rocket to another finicky system isn't the best way to do things. (granted, aircraft are finicky, but the B-52 ain't no pretty princess) Airship launch isn't going to get you to the moon cheaper.



Just ground launch like everyone else has been doing for the past hundred or so years, you can bet that Musk ain't doing it because it's *more* expensive. It ain't cool, it ain't what PopSci will have on its cover page, but it works, and it works well. (if anything, ground launch hold-downs give you a factor of safety that makes the whole thing orders of magnitude cheaper in terms of OH FUCK WILL IT LIGHT?)

There have to be failures. The rocket technology is proven, but it is no longer backed as a system for warfare. ICBMs were the basis of rocket technology. Now, there is no cold war going on. This means limited funding for large rockets. You might call it a mature technology.

One of the key indicators of a mature technology is the ease of use for both non-experts and professionals. Another indicator is a reduction in the rate of new breakthrough advances related to it - whereas inventions related to a (popular) immature technology are usually rapid and diverse,[2] and may change the whole use paradigm - advances to a mature technology are usually incremental improvements only.

Increasingly the space race becomes a commercial race, tourism, satellites and similar things.

Because rocket launch from planes is turning out to be cheaper in terms of commercial use and private foundations. They get used more. It is not as mature a technology as rockets.

The next step is unproven technology like very large blimps or airships to launch from ships. This is an immature technology which will have lots of failures, but in the long run has the potential for larger breakthroughs.

This is false.

We know a few things. Firstly, we know what we want to get into space for a certain mission. Secondly, we know where we want it to go. This gives us a nonrecurring payload cost and a delta-V. We also know what propulsion system we want to use. (say, five Rocketdyne F-1 engines running on LOx and RP-1) From this we can get a specific impulse. Knowing the delta-V and the specific impulse, we can get a mass fraction requirement. Now, the trick is to make a rocket whose structure is light enough that the fraction left over (the "payload fraction") is large enough to accept the payload.



From this, we can get the necessary size of our rocket. This number may appear somewhat fuzzy, but is much more concrete than you might think, as it's strongly controlled by materials constraints.



So, we have our rocket. Now we need a balloon. Pegasus is ~20 Mg (~44klbs), so you need a fairly large airship to hoist it. Airships are guided by some VERY hard density laws. Hydrogen (I'll be nice) is about 89 grams per cubic meter[wiki] at STP, air is about 1.2 kilograms per cubic meter. So that works out at about 1.1 kg of buoyancy per cubic meter of lifting gas. This has to cover the balloon, the launch instrumentation, the rocket, and the connecting apparatus (rope). Oh, and that's at sea level, by 50k feet the ambient air density has dropped to 15% of the sea level density. (you can vent off some hydrogen, but you still have less lift per cubic meter)



50k feet is only 4.25% of the ISS's altitude. But maybe that's too high, at 25k feet you're still at 45% of the local density, and 10k feet gives you 75%. Maybe you can haul 20Mg up that high? (Saturn V was 3 Gg, for comparison, Falcon 1e is 35 Mg)



Remember, atmospheric drag is far smaller than gravity drag and delta-V requirement when it comes to calculating fuel required.



EDIT: the math is rough, but I'm currently trying to puzzle through how in hell to do Nyquist plots by hand (fuck this class) but you get the idea.

But what if the balloons were full of helium 3?????!

It's 3 times more buoyant I thnk.

note: I guess I've been a little assholish, and I apologize for that, I just have microscopic patience for most PopSci Space "Science."

There are a good many "Aerospace Engineers" out there that do very little but come up with crackpot ideas.



These problems have been examined thousands of times by tens of thousands of people. Most of the time there's a hard limit standing in the way, usually materials and scaling. The best way to tell is if their device is "too good to be true"

From where I'm standing, you haven't been anywhere near blunt enough. I think it would be a good idea to develop a more dismissive and abrasive posting style for these situations, because currently your detailed and seriously toned responses lend an undue amount of perceived credibility to the "ideas" seemingly discussed.

Not a thing. I don't mind the abrasiveness, it was not rudeness. I am thinking along the lines of a continuum when you do things. You have a budget lets say $100,000,000 for space as an example. You spend 70% of on reliable stuff, 20% of it on experimental stuff like airplanes with rockets attached to launch into orbit, and 10% on pure blue sky stuff, a space glider the size of the concord jet with clamps designed to hold a rocket than release it.

This is another slightly off idea. The question is it worth the risk. The culture I play lends itself to outlandish risks in face of near impossible odds.

There are plenty of crackpot ideas that have absolutely no chance at all, perpetual motion machines, etc.

But, there are some crackpot ideas that won't work like the Heim Drive but will lead somewhere probably not where you expected. For example, airship or high altitude glider launch is probably a lot more feasible than space elevators.

>implying this is any better than a perpetual motion machine.

Here's the thing: we know that aircraft launched rockets are possible. Orbital does it all the time, the military blows people up with the concept on a (nearly) daily basis, and a number of folks have done balloon launched rocketry. (not just limited to Romania or wherever)



The problem is scale: you're not going to get a whole lot bigger than Pegasus and still find yourself capable of air-launch. In terms of what we can do with the technology, we've pretty much maxed it out just from the physics of flying anything. Buoyancy and lift are not kind to heavy things in an atmosphere. You're not lifting a Delta IV in an airship or on an airplane. No matter how much money you pour into it, hydrogen is the least dense gas (and has its own problems), that puts a HARD upper limit on the size of this thing per size of balloon, eventually the balloon isn't worth it.



I only give space elevators some leniency because even their advocates admit they're hundreds/thousands of years off. We don't really know what we'll have then to play with. But at the moment, lofting large launch rockets with balloons is about on par with space elevators.

EDIT: your distribution should be 90%, 9%, and 1%. Well, or 95%, 4.5%, and 0.5%, depending on the economics of it all. (remember, the well-founded stuff is a moneymaker if you play things right)