Jan 012011
Get it while the gettin’s good!
http://www.up-ship.com/blog/eAPR/ev3n1.htm
127 pages of awesomeness related to the Convair NEXUS super-booster, the Convair XP-92, von Brauns “Ferry Rocket,” a 1982 McDonnell-Douglas AFT concept and the Lockheed GL 238 cargo plane. If you like spacecraft, ramjets, gas-core or solid-core nuclear thermal rockets or Project Orion, you’ll love this issue.
Remember, APR is no longer taking new subscribers, so unless you’re already a subscriber, the only way to get this issue is… to buy this issue. Go for it… it’s cheap!
16 Responses to “APR issue V3N1 is Now Available”
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I’m not sure the tables on p. 59 and 60 line up with the captions. The launch weight differences are suspiciously small, and the payloads are shown as the same (1M lb.)
I also believe the H2 tank fabrication process was actually used by General Dynamics for the LNG tanker program in the 1970s. The tank fabrication facility was on the Cooper River in Charleston, SC, just north of the Naval base.
> I’m not sure the tables on p. 59 and 60 line up with the captions.
That’s what I get for not having an editor. Rather than relatign to the 1Mlb and 2Mlb versions, both tables deal with different versions of the 1Mlb version.
Got mine. Awesome work again Scott.
Very interesting issue Scott. Many Thanks
Ehricke always argued that bigger was better in terms of launch vehicles, and that economies of scale became more favorable as the vehicle got bigger. But inversely, was there a lower threshold beyond which the concept was unworkable, economically or otherwise? For example, would an EELV-class Nexus be a workable design (assuming sufficient flight rates, availability of suitable propulsion, etc.)?
> was there a lower threshold beyond which the concept was unworkable, economically or otherwise?
Yes.
1… as a vehicle gets bigger, drag losses become less important. Inverse: as a vehicle gets smaller, drag becomes a bigger issue.
2… As a vehicle gets bigger, it gets easier to make parts to finer *relative* tolerances. Inversely, as a vehicle gets smaller, it gets harder to make, say, tank walls with high tolarances without making them so-and-so many thousandths of an inch thicker.
3… as a liquid fuel rocket gets bigger, the relative length of the combustion chamber gets shorter. A truly gigantic conventional bell engine would have a combustion chamber that is nearly a flat disk… but a small rocket will have a combustion chamber more of a lengthening cylinder. This is because the propellants need a certain residence time in the chamber to combust efficiently; since they are moving, residence time relates to chamber length.
4… Pumps like to be big, not small. They work better and with relatively smaller leak paths and lower cavitation trouble than small pumps.
5… A modern laptop computer has the computational power to control something the size of a Saturn V, or something far bigger. But essentially the same computational power would be required for a small space launcher. Unlike turbopumps, howerver, computers are forever getting smaller.
6… Welding giant structures is easier than welding tiny structures. A perfectly acceptible bead on a giant tank would be a hugenormous massive glob on a tiny tank.
Good analysis, thanks. In reading the article I was thinking about the USAF requirement for a reusable EELV replacement and wondering why someone didn’t propose a mini Nexus with a few RS-68s or RS-25s. I can see why that might not be such a good idea, especially considering the drag issue and the likely need for a substantial interstage fairing (which is essentially dead weight). Possibly you could build a wafer-like second stage a la AMLLV, but you would still need an outside fairing for the payload.
I guess there is also the cultural bias inevitable to any procurement system, i.e., we’ll build tube-shaped boosters, or tube-and-wing recoverables, because that’s what we know how to build, and that’s what the customer thinks a rocket looks like.
> we’ll build tube-shaped boosters, or tube-and-wing recoverables, because that’s what we know how to build, and that’s what the customer thinks a rocket looks like.
There’s also the fact that tube-shaped tanks are, compared to NEXUS-style tanks, both easier to make and lower mass per unit volume (especially so for the beaded-sphere-torus LOX tank).
In theory, if you could take a full-sized functional NEXUS vehicle and do something terribly sci-fi to it liek feed it througha replication and crank out a version one percent full size, in many ways theoretically it’s still work. The tanks would still be able to handle the same internal pressures with the same margins of safety, for instance. But of course there’s the probelm that the engines *wouldn’t* work (at least not efficiently), and a lot of the structures would not be so thin that they would be incredibly suceptible to damage from outside forces… like handling, or running into a bird. Or, perhaps importantly, corrosion. Alumin is an extremely reactive material; it survives contact with oxygen by building up a very thin, hard, transparent layer of aluminum oxide. The layer is extremely thin, and is rarely measured in terms of mass for full-scale vehicles; in the scaled-down vehicle, though, the oxide layer would not be scaled down in thickness, but would become the *same* thickness. Anti-corrosion coatings would also need to be applied at the same thickness, which would make their mass contribution that much greater.
Haven’t received mine though I paid on Sunday. Help!
> Haven’t received mine though I paid on Sunday.
You paid on Sunday… and the download instructions were emailed to you on Sunday.
—–Original Message—–
>From: Scott Lowther
>Sent: Jan 2, 2011 1:30 PM
>To: “wesleyj@sxxxx”
>Subject: Re: Notification of payment received
>
>eAPR v3n1: download order
However, you’re not the first to complain of not getting the email notification. Something screwy seems to be going on; I’m hoping that the emails are simply being delayed, and that everyone I’ve sent an email to will *eventually* get an email. For instance, I sent email notifications about the availability of V3N1 to the emailing list… and only 25 sold. GAAAAHHHHRRRR!!!!!!
Finally received the e-mail:
Sent: Jan 2, 2011 1:30 PM
Received: Jan 3, 2011, 10:47 PM
Was this via your server or PayPal?
> Was this via your server or PayPal?
All such emails are sent out manually by yours truly. Clearly, something screwy is going on, and a serious delay has been introduced. Not to *all* emails, since I got a few fairly quick responses… but to a *lot* of them.
[…] mentioned in the comments here, a lot of emails I’m sending out are either not getting to the destination… or are […]
Yes, I too am patiently awaiting my download instructions. I’m sure it will turn up eventually.
Perhaps a contact with your email provider is in order? I’m not sure what your email connection is.
> I too am patiently awaiting …
Sigh. I’ve now sent the info to you *three* times.
Arrrrgh.
I got it!! Wow, the article about the Nexus is worth the price of the issue all by itself. Comes with your choice of upper stages: Gas-core nuclear thermal rocket or Orion nuclear pulse rocket!
The article about von Braun’s Colliers rocket was also a fascinating read. The entire first stage was hypergolics! That was a disaster waiting to happen.