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Official Armadillo Q&A thread

Posted by: John Carmack - Tue Jun 15, 2004 8:01 am
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Official Armadillo Q&A thread 
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Space Walker
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Post Re: Great video!   Posted on: Thu Jun 17, 2004 3:06 am
Webkabouter wrote:
2. is it possible to mount a camera on it like on the previous vehicle (the "lander")?


I can answer this one:

Yes - we brought out the little camera with us to mount to the nose cone looking down, which we've done on that nose cone before, but because we were racing the daylight, we didn't have time to attach it before the flight.

Matthew Ross
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Post    Posted on: Thu Jun 17, 2004 3:06 am
John or Matthew, could you give us an idea of how loud the engine is on the streamlined ship shown in the "perfect flight" ?

rough dB ? is it deafening when nearby?

thanks,
james


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Post    Posted on: Thu Jun 17, 2004 9:35 am
Mr. Carmack

I'm wondering why you don't place the jetvanes as parts of a ring at the outside of the exhaust (the same principle as the x-31 used for thrust vectoring)...this way you only loose engine efficiency when the vanes are actuated; if they're in their rest positions they will be outside the exhaust.


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Post    Posted on: Thu Jun 17, 2004 10:56 am
Congratz on beautiful flight !

I know such developments would be long way down the road, but ...
Questions : would your mixed monoprops have significant obstacles working in space for extended periods of time ? Freezing, heating issues, radiation vs electronics ?
How much of the experience you have gained would apply to developing a lunar soft-lander ? GPS wouldnt be available of course.


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Post    Posted on: Thu Jun 17, 2004 11:27 am
Firstly, to all those at Armadillo Aerospace: that video is truly awesome, and a real milestone. You must all have grins a mile wide at the moment - I know I do!

From reading the project updates on a weekly basis since 2001 or so, it seems you guys have been making much faster progress recently, and it looks like it's all coming together very well. From the bottom of my heart, I'd also like to say thankyou for posting the weekly updates, the bad with the good, as they're truly fascinating and a window into the level of work required. I'm surprised no newspapers are publishing this on a weekly basis, quite frankly!

Secondly, now the test has gone so well it looks like you're focussing on the big vehicle next week, with the hover tests and hopefully the boosted hop later. Do you envisage having to build a new big engine from scratch after further tests, or do you feel relatively happy with the current configuration?

I'd also be interested to hear how well you feel the small engine design will scale with regards to longevity; whilst the current design seems pretty good, it looks like you're not completely happy with the compressed pack configuration yet, and the time required to light it. Do you foresee there being any heat or weakness problems with the vanes on a big engine when you're driving the engine at full strength for extended periods of time, or with lighting the engine in mid-air after falling back from the apogee with the engine powered down?

Truly awesome work; to me this does actually seem more of an achievement that SpaceShipOne, despite the technical achievements of SS1; I guess it's a scale thing :) If you ever need anything sorted in the UK, drop me an email!


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Post    Posted on: Thu Jun 17, 2004 11:39 am
Roel wrote:
I'm wondering why you don't place the jetvanes as parts of a ring at the outside of the exhaust (the same principle as the x-31 used for thrust vectoring)...this way you only loose engine efficiency when the vanes are actuated; if they're in their rest positions they will be outside the exhaust.

I presume this is for a couple of reasons; firstly, the vane actuators would have to be mounted sideways-on to the engine for this to work, which would presumably need a longer vane axle and so is probably bulkier and far more likely to give way. Secondly, to be outside the exhaust and be able to actuate them in sufficiently to provide a large thrust vector you would presumably have to have larger vanes...

So I'd guess that it's a tradeoff between a loss in efficiency for flow-central vanes, and a gain in simplicity and strength. I think they mentioned the loss as being "a few percent", so I guess the tradeoff was worth it. I'm interested in a response to this as well, come to think of it :)


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Post    Posted on: Thu Jun 17, 2004 2:00 pm
No question, but a note of congratulation -- I've been showing the "perfect flight" video to various non-space friends of mine (who've never seen the DC-X videos), and at first they frankly refuse to believe that it's real. "That's... uh... Photoshop?" was one response that I got yesterday. When I explain that no, it's absolutely real, and it was done not by NASA but by a bunch of geeks volunteering their time in a shack in Texas, you can almost literally see the circuits shorting out between their ears. From here on out, you're going to be blowing a lot of people's minds.

Okay, so I do have a question: any plans to do a horizontal translation, ala DC-X? Don't know why that would be of any use to you (except to prove maneuverability), but it sure would look nifty.


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Post    Posted on: Thu Jun 17, 2004 2:09 pm
Congrats on your perfect test hop! That's the coolest video I've watched in a while.

Question: You have taken a design-as-you-go approach which seems like it is bearing a lot of fruit right now. This engineering approach seems like it is used most often in the software world, where a test run is only a recompile away, and least often in the rocket science world, where a top-down approach rules the day. Do you believe there will be a point in the future where your approach becomes too difficult to maintain because of the complexity of what you are trying to do or because of the cost of consumables for each test run?


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Post    Posted on: Thu Jun 17, 2004 2:16 pm
Rowan B wrote:
So I'd guess that it's a tradeoff between a loss in efficiency for flow-central vanes, and a gain in simplicity and strength.

You'd also lose roll control.


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Post    Posted on: Thu Jun 17, 2004 3:18 pm
steelie69 wrote:
[snip] is it deafening when nearby?


I don't know what the dB levels were (we've measured them at the shop on other engines, but not this one out at the 100 acres), but at about 50 yards away where I was shooting video, it was just loud enough for me to still want to wear hearing protection.

Matthew Ross
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Post    Posted on: Thu Jun 17, 2004 4:11 pm
Matthew Ross wrote:

but at about 50 yards away where I was shooting video,..


Just wanted to congratulate you guys on both your video and stills---very high quality. And thanks for sharing them with us!

--Ralph

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Post What's the absolute minimum operation cost?   Posted on: Thu Jun 17, 2004 5:40 pm
Mr. Carmack,

Dream with me for a minute. If you had 10,000,000 customers per year, what would be the absolute minimum marginal cost per flight? What's the fuel cost to 60 km up for 150 lb person? After a million flights would you need a pilot any more? Do you get much in the way of weight/operation savings going to 6, 12, 100 or 500 people per flight? Could you do it for $1,000 per person per flight?

Sam Dinkin

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Post    Posted on: Thu Jun 17, 2004 6:42 pm
Congratulations on an excellent flight! Landing on that tiny base still looks miraculous. Your flightworthiness looks ever stronger.

After the flip-over on the small lander, you were musing about making the position-holding control independent of roll. Although it looks less necessary on these short flights with the faired vehicle, I still believe this is an essential safety characteristic of your control system. The little lander showed significant roll on the ascent and was probably close to your 20 degree limit before it started descent.

The aspects of control are: altitude, attitude (pitch+yaw), position and roll. I think the last two should be the lower priority, subject to override and as I say above, independent.

Another thought: Can you get a different waiver, not time-related, that will allow you to explore manoueverability, all within say 5m of the ground? so you can hover the vehicle 10m North, East, South, West, then land. Or you could try out tipping and recovery? Deliberate roll?

Thanks, as ever, for sharing all your progress both triumphs and disasters with us.


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Post Software   Posted on: Thu Jun 17, 2004 8:52 pm
In a recent interview John Young described how on its very first flight Columbia came close to not coming back because incorrectly modeled aerodynamics had been incorporated into the software. During descent the nose yawed to the point (which didn't take much) where it verged on unrecoverable. He said "if it had not trimmed out Columbia probably would have rolled twice before the wings came off."


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Post    Posted on: Thu Jun 17, 2004 10:08 pm
Oh, another question. Do you have any comments on Alridge report ? We'd love to hear from people who actually do something themselves to make future happen.


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