Comments for Gravity Loss

Comment on Fed Up by Bob Steinke

Bob Steinke — Wed, 02 Jul 2008 22:22:05 +0000

“You’d need a refuel and go again reusable launch vehicle (RAGA RLV) that has turbopumps.”

I’d like to find out more about why you feel turbopumps specifically are a necessary part of a solution. I’ve heard convincing arguments that pressure fed systems could be inexpensive launch vehicles. Their GLOW to payload ratio would be large, but the important metric is cost, and simpler systems can cost less per pound. If you think pumps are necessary, why wouldn’t piston pumps or pistonless pumps work? Even if turboumps are the best solution, why do you think the other solutions are useless dead ends and not just suboptimal?

You’ve done a lot of great quantitative analysis for some of your other posts. I’d like to see you dissect the tradeoff between turbopump and non-turbopump vehicles. This isn’t flamebait. I genuinely want to see the reasoning and analysis behind the ideas when I hear conflicting opinions.

Comment on Fed Up by truthwalker

truthwalker — Wed, 02 Jul 2008 18:44:08 +0000

Just so you know the Air Force released its official ‘White Paper’ recently on the future of air power in the US. One of the statements made (and remember this is an official government paper) If we don’t start investing heavily in our aerospace companies now, we will completely lose domestic aerospace capacity within ten to fifteen years. Pretty scary stuff.

To bad we are the only ones reading it.

Comment on Fed Up by K. Luojus

K. Luojus — Thu, 26 Jun 2008 10:23:03 +0000

Well, I see a lot of possibilities still ahead of us. Bigelow is putting up the “destination”. AA and XCOR might get enough funding and at least a whole lot of important experience out of RRL. And looking at AA they really haven’t been funding constrained in the past…

You are counting out Scaled, based on their choice of hybrid propulsion. I see them as the firm that opens up the field for space tourism and that will definitely help the funding situation for the other NewSpace players (Space Adventures fly people too infrequently to make a real market, and Scaled/Virgin will probable make a real market…).

There are also other things in the horizon that can turn out for the better. SpaceX might just live up to the expectations, and when Bigelow puts up the destination, the situation will definitely change. I see the ULA bunch leaping on to the capsule/EELV road once there is a destination and paying customers lining up.

Comment on Fed Up by Afonso

Afonso — Sat, 21 Jun 2008 11:40:45 +0000

Mostly agree with your remarks, but I think there IS a good cause for long-term optimism: the Space Elevator concept.
Even buraucrats and politicians have understood that sooner or latter it will be build. The usual problem tough: being a long term project the *glory* of making it happen will have to be shared over many *generations* of politicians, something they don’t seem to be able to cope with…

Comment on Fed Up by Gordon R. Vaughan

Gordon R. Vaughan — Thu, 19 Jun 2008 20:23:56 +0000

Yeah, it’s frustrating. I saw the writing on the wall and gave up on NASA over 20 years ago (I guess I could insert a comment here about the ISS, but anyway…).

Not that NASA isn’t doing some neat stuff, they are. Quite a bit, actually. But the bigger the project, the more it seems to suffer from bureaucracy and politics, and of course manned spacecraft development has the biggest projects of all.

Anyone building a spacefaring fleet, whether government or other, will have to be at it consistently for many years, as you note. More than that, they’re going to have to constantly work to make the most out of what they’ve already got, reusing pieces as much as possible rather than starting from scratch every time.

I wrote about that a couple of years ago:

Energia’s ISS Stance Points Out Key Flaw in NASA Strategy

The basic point is that space stuff is so expensive to develop, we need to make sure we get the most out of it once we do, which also raises production quantities and so lowering unit costs.

There’s also some more in that article about what I think would be a proper space development strategy. We need to start being strategic. Without that, even spending huge amounts of money & time ($100 billion/24+ years for ISS, for example) doesn’t get you very far.

Comment on Fed Up by Jonathan Goff

Jonathan Goff — Thu, 19 Jun 2008 05:28:49 +0000

I don’t blame you for being frustrated. You’re right that only a handful of firms are making any progress at all, and most of them are badly undercapitalized. I used to think there were easy solutions to some of these problems, but the truth is, there are no solutions that don’t take a lot of time and a lot of hard work. I’m just hoping that if some of us firms in the US can make enough of a success of what we’re trying to do, that maybe that can spark other groups in other countries to start following suit. But momentum is hard to overcome.

Heh. I’m not sure I actually said a single new thing in that whole paragraph.

~Jon

Comment on Testing Embedding by Jonathan Goff

Jonathan Goff — Wed, 11 Jun 2008 03:38:13 +0000

Heh. That’s pretty cool. Almost enough to get me interested in Mars. Pretty darned huge orbiter ship though for a 3-person landing party…

~Jon

Comment on The Last Five Kilometers by truthwalker

truthwalker — Sun, 08 Jun 2008 22:19:53 +0000

So I did some more reading parasails rock.

Comment on Hypersonic Cruise for the V Prize by sicsok

sicsok — Tue, 03 Jun 2008 16:11:34 +0000

About the engine I would check (among others) US Patent US 7111449!
No startup and no speed limits. Serious work too and all this with higher than currently known efficiencies in all but start up speed regime.
Not included but the nozzle can accomodate rather simle thrust-vectoring method too.
Sounds too good. But too good compared to what?

Comment on Hypersonic Cruise for the V Prize by 4751 ADSM Florida

4751 ADSM Florida — Sat, 31 May 2008 21:42:07 +0000

Randy, spent a few years in the Florida Panhandle working with Vitreo and USAF, in uniform, on the Bomarc A and B bird. Primarly in the telemetry side of the house.

I have walked into the melt down crater when the bird literally burned down into the shelter.

Ramjets: I was not aware of the runaway Ramjet, it may have happened after I departed.
We routinely sent a dmg to blow the bird after the mission.
The thumbnail tuning for that point in history was the Ramjets could take a frame to MACH 10. We knew when and what would fail before it reached 10.

Most cases kept the bird at about the speed of the F4 of the day. Remember, the gulf of mexico at the time was full of “Fishing Boats” for all over the world. I am sure some of them were collecting data.

What happened with the C Bird?