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Xaero

Posted by: Marcus Zottl - Tue Dec 07, 2010 12:36 pm
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Xaero 
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Post Xaero   Posted on: Tue Dec 07, 2010 12:36 pm
http://masten-space.com/blog/?p=562

Awesome!

Can't wait to see that baby fly! 8)

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Post Re: Xaero   Posted on: Wed Dec 08, 2010 11:12 am
Love that!

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Post Re: Xaero   Posted on: Wed Jan 12, 2011 9:49 pm
Xaero is now Brutus? :?:
(nevermind, that seems to be an old name: "Meet Xaero. Formerly known as Brutus, Xaero has a carbon fiber aeroshell,..." (from the linked blog entry in the first post of this thread))

http://flightplan.xprize.org/post/27178 ... or-our-two

(interestingly, I got that link via the NGLLC facebook page. I didn't suspect anything new from them anymore :))

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Post Re: Xaero   Posted on: Tue Jan 18, 2011 1:19 pm
More hold down testing of Xaero/Brutus:
http://www.youtube.com/watch?v=KrNvckQwfpw
http://www.youtube.com/watch?v=D8jBc9tOWCE

Quote:
... our XA-0.1-E2 rocket vehicle nicknamed Xaero in the "Brutus" configuration.


I'm getting a bit confused with all the different names. So the vehicle is still Xaero, but what is a "Brutus configuration"? ;)

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Post Re: Xaero   Posted on: Tue Jan 18, 2011 6:41 pm
Marcus Zottl wrote:
More hold down testing of Xaero/Brutus:
http://www.youtube.com/watch?v=KrNvckQwfpw
http://www.youtube.com/watch?v=D8jBc9tOWCE

Quote:
... our XA-0.1-E2 rocket vehicle nicknamed Xaero in the "Brutus" configuration.


I'm getting a bit confused with all the different names. So the vehicle is still Xaero, but what is a "Brutus configuration"? ;)


I agree it's confusing, it's easier to keep track of nVidia part numbers! From what I've been able to figure out, Xaero came about from the XA part of the name, kinda like Xombie which was the name of a previous rocket they built. Brutus is a joke nickname which came about from the E2 part of the name, from the Julius Caesar quote "Et tu Brutus"

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Post Re: Xaero   Posted on: Tue Jan 18, 2011 7:20 pm
Thank you for educating me on the Brutus side of things. I never had Latin so I'm not really good at "connecting" various terms with Latin quotes. ;)

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Post Re: Xaero   Posted on: Wed Jan 26, 2011 4:14 am
Indeed, I named it Brutus as a pun, but unsurprisingly some of the guys are pushing to change it after I left the company. To quote Jon Goff (who's also no longer at MSS) on Twitter recently:

"So the Delta-IVH that just flew was nicknamed "Betty".

"Back when we were still calling it XA-0.1B, Mike threatened to call it "Betty" (or maybe Wilma) if we didn't find something cooler.

"That's when we came up with Xombie (for 0.1B), Xoid (for the 0.1D we never built), and Xoie (for what ended up being our NGLLC L2 vehicle).

"0.1F was going to be Foxie, 0.1G Xogdor (and a second tail number was going to be Xorg). All leading X's pronounced like Z's of course.

"F never really got built, and the second incarnation of Xoie (XA-0.1E-2) was going to be Brutus. E-2 Brutus?

"According to Dave the official name for that vehicle is Xaero. Though last I heard, the 100km follow-on is still being called Xogdor.

"Xogdor the Meltinator...Meltinating the countryside! Though hopefully not meltinating all the peasants (the FAA frowns on that these days).

"Anyhow, this bit of Masten nostalgia is brought to you buy a guy who had a lot of fun working on building rocket-powered robots in Mojave.


As a correction, it's Xogdor the Burninator. Ian Garcia (also no longer at MSS) named that one. Xorg is mine, after the Fifth Element, but it lost out to Xogdor.

The original idea was that 0.1 was the first rocket they built, 0.2 was a 36" tank version, dot dot dot, to 1.0, the 100kg to 100km rocket. Then 0.1 crashed.

Then we built 0.1B, which had a bunch of parts off 0.1, including four 500lbf single-axis hinged engines. Then the engines died enough we couldn't fix them any more.

We modified B into B-750 by removing the four 500 lb engines, putting in one 750lbf dual axis gimbaled engine, and lightening the rest of it. The vehicle was called "B" (bee) for the most part, until there was threatening of bad naming as Jon mentions. He came up with Xombie, which I thought was annoying, but it stuck and got us a lot of publicity.

So...
A: Original 0.1, never called A.
B: The one just described. B-750 won LLC-1.
C: A vehicle very similar to B with four engines, wildly unoptimized. Management wanted it, we didn't, we won.
D: B-750 with an aluminum frame to win LLC-1. We pulled enough performance out of B-750 that it was unnecessary.
E: Xoie. Won LLC-2. E2, Brutus, now Xaero. (Ian gets some credit again in that he came up with "Aeroxoie" and "Xaeroie") Same vehicle but with an aluminum fuel tank rather than a leaky composite one, different arrangement of pressurant, and an aeroshell.
F: Foxie. Xoie-sized vehicle, but with a 3000lbf engine, or other engine setup to have better accel.
G: Xogdor, Xorg. A larger version of Xoie.

https://secure.wikimedia.org/wikipedia/ ... ,_Brute%3F

I came up with the overall planform for this new E vehicle, and hired Scott Zeeb to do the deployable landing gear for it, so I'm looking forward to seeing it fly. I hope it doesn't crash too quickly.


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Post Re: Xaero   Posted on: Sun Jan 30, 2011 6:53 pm
Ben wrote:
I hope it doesn't crash too quickly.

As opposed, I guess, to it crashing slowly ... :lol:

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Post Re: Xaero   Posted on: Thu Feb 03, 2011 10:26 pm
To clarify, all reusable rockets either crash or are retired. Retirement is fairly rare, as it's either not developmentally useful, or people get entrained by the sunk cost fallacy and keep operating with a given capability because it's there.

I look forward to seeing this new vehicle fly, and I hope it performs really well. It's a difficult thing that it's trying to accomplish, harder than the lunar lander challenge. I hope it demonstrates a lot before the industry-standard TLOV, "tragic (or total) loss of vehicle".


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Post Re: Xaero   Posted on: Tue Feb 22, 2011 10:35 am
Xaero Tether Flight 2.mov

http://www.youtube.com/watch?feature=pl ... 8rOcDW4Pbk

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Post Re: Xaero   Posted on: Tue Feb 22, 2011 2:38 pm
one word: smooth!


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Post Re: Xaero   Posted on: Sun Mar 13, 2011 9:37 pm
Masten posted a video of Xaero running to depletion.

http://www.youtube.com/user/mastenspace ... npXDK1GB3w

Can somebody explain the purpose of this kind of test? I don't remember seeing Masten or Armadillo running any of their engines to depletion before - I always thought running an engine dry was really bad for it.


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Post Re: Xaero   Posted on: Mon Mar 14, 2011 2:56 am
It's a standard test at both. We ran the tube rocket to depletion last week.

In a hover test, it gives you the full delta-v of the vehicle: multiply the flight time by the acceleration of gravity (9.8m/s). It also shows that the engine can be throttled well at the low range.

The test also integrates the mixture ratio over throttling to tell you which propellant is going to run out first. In that test, it was fuel that ran out first. For some engines that is bad, but a regen chamber can be built to survive fuel depletion.


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Post Re: Xaero   Posted on: Mon Mar 14, 2011 3:09 am
Thanks for the info, Ben.

Would you rather run out of fuel or oxidizer first? I figured oxidizer since a fuel-only flame would be cooler, so it struck me as odd to see Xaero run out of fuel first. Is an oxy-acetylene torch a good analogy...you're supposed add oxygen after you have the flame lit and shut the oxygen off before you shut the fuel off.

Is there a 'hard-stop' corollary to a hard-start? My intuition would suggest that if an off mixture ratio at start-up is bad, an off mixture ratio at shut down might be bad, too.

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Post Re: Xaero   Posted on: Mon Mar 14, 2011 4:32 am
You'd rather run out of oxidizer first. On turbopumped vehicles, you can't run out of either or the compressor will overspeed and explode. So on those they sense whether there is propellant in the line and if not, shut it down. You can do similar pretty easily on a lox/hydrocarbon pressure fed vehicle, an optical sensor capable of detecting the presence of fuel in a line is an off the shelf item.

Running out of fuel isn't comparable to a hard start, it's 'just' a severe mixture ratio excursion. For a radiatively cooled or fuel film cooled engine that runs hot, it can mean the engine itself is consumed by the oxidizer. That's undesirable, but it's essentially just a big sparky plume rather than an explosion. Until the wall is burned through, the thrust vector suddenly goes off axis, and the vehicle goes out of control.

Because the initial hardware temperatures are lower and the chamber isn't up to pressure yet, at start you can get away with extremely off-nominal mixture ratios without damage. Starting with the oxidizer running and turning on the fuel isn't uncommon, which runs the engine through stochiometric (hottest running). See for example the white cloud before startup here: http://www.youtube.com/watch?v=jetZ0o509F8 that's a lox lead.

A hard start is when mixed fuel/oxidizer is present in the engine before the engine is lit. This can happen in a horizontally tested engine, where purged propellants can pool, or in an engine where the igniter interlocks aren't working well. In a multiple chamber vehicle, it can happen when all of the chambers start flowing but not all of them are lit; the unlit ones will be lit externally and the peak pressure usually exceeds the material strength (i.e. the engine explodes). A group out at FAR were flying a ten chamber rocket, overrode the ignition interlock, and had one chamber hard start and destroy the two adjacent chambers. It ripped the rocket off the rail and crashed.

Externally it can be difficult to tell the difference between a hard start and a manifold contamination explosion, which is common in kerosene engines. In the end you look at the pieces and figure out what blew up first.


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