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Comment Re:Not in Africa and all of Asia (Score 1) 1058

I wouldn't be so sure that they will be cheaper to rent than it is to own a car.

Of course they won't be. Somebody has to own that car (ie, the car rental company) and they're going to want to make a profit on their investment. Per mile, it will always cost more to rent than to own.

Now, an individual might -- by restricting the amount that they drive -- not pay as much out of pocket for that car, because they're sharing the miles with other renters. And for some people that might make sense. But generally not for folks who don't live in extensive densely populated conurbations (aka, "targets", for those who remember the Cold War).

Comment Re:Well... (Score 1) 44

RP-1/HTP works fine. The British Black Knight had over 20 successful (suborbital) launches with it, and the later Black Arrow, whose first two stages were RP-1/HTP, put the UK's only independently-launched satellite into orbit, back in 1971.

Given the number of first-rocket attempts which have failed (sometimes explosively) because of things like frozen LOX valves, going non-cryogenic has a certain appeal. Especially since they can pretty much stockpile the things in a fueled state for rapid launch.

Any rocket fuel is likely to kill you if you look at them funny. Some more so than others, sure, but nobody is using liquid ozone or FLOX (liquid fluorine-oxygen) as an oxidizer any more either. (Or worse. See the book "Ignition!" for a fun look at early rocket fuel experiments.)

And for what it's worth, the mass ratio of an aluminum beer can (12 fl oz size) is a hair under 28:1. ;-)

Comment Re:Revolutionary Rocket aka aerospike engine (Score 3, Informative) 44

You're confusing aero spike engines with simpler (but heavier) spike engines.

In an aerospike, aerodynamic forces (often with the assist of gasses injected at the base of the engine) form the "pointy" part of the spike, so there's both the lighter and easier to cool aspect. Also known as a plug-nozzle, but the latter are usually (a) circular and (b) even shallower than this linear aerospike.

Spike nozzles (circular ones) have also been flight tested, but yeah, the tail of that spike is heavy -- and also not what you want if you're planning to reuse the vehicle, because it aggravates reentry heating. (Doesn't look like this is what ARCA is planning though, I guess they're just going for cheap and disposable. Maybe reusable will follow.)

NASA never had any problems with their X-33 aerospike, it was all down to the weird-ass V-shape fuel tank configuration.

Comment Re:Too good to be true. (Score 1) 203

True, but these guys are in Colorado. We get maybe a dozen cloudy or hazy days a year. And it's a semi-desert, no muggy days.

Yeah, it might not work so well in the Mississippi valley region.

OTOH, if they're shifting to a frequency of infrared not absorbed by H2O, it might not care about puny water vapour.

Comment Re:Tell us, Einstein, what is Rust written in? (Score 3, Insightful) 236

Uh, nope.

From WIkipedia:

The language grew out of a personal project by Mozilla employee Graydon Hoare, who stated that the project was possibly named after the rust family of fungi.[11] Mozilla began sponsoring the project in 2009[10] and announced it in 2010.[12] The same year, work shifted from the initial compiler (written in OCaml) to the self-hosting compiler written in Rust.[13] Known as rustc, it successfully compiled itself in 2011.[14] rustc uses LLVM as its back end.

(emphasis added)

However, I'll grant that LLVM is written in C++.

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