Community > Forum > Official Armadillo Aerospace Forum > Official Armadillo Q&A thread

Official Armadillo Q&A thread

Posted by: John Carmack - Tue Jun 15, 2004 8:01 am
Post new topic Reply to topic
 [ 2523 posts ] 
Go to page Previous  1, 2, 3, 4, 5, 6, 7 ... 169  Next
Official Armadillo Q&A thread 
Author Message
Launch Director
Launch Director
avatar
Joined: Thu Oct 23, 2003 4:31 pm
Posts: 18
Location: UK
Post Armadillo   Posted on: Fri Jun 18, 2004 12:42 am
Excellent movie and yes it did seem unreal!!

I'm a fan of SS1/Rutan and Starchaser (coz I'm a Brit), but it is really nice to see the other team starting to test hardware and system approaches.

Great work!!

_________________
We're going back...
www.transorbital.net/ | www.lunacorp.com | www.asi.org | www.space-frontier.org


Back to top
Profile
Spaceflight Participant
Spaceflight Participant
User avatar
Joined: Tue Jun 15, 2004 7:54 am
Posts: 94
Location: Dallas, TX
Post More answers   Posted on: Fri Jun 18, 2004 1:49 am
jet vane positioning:

Vanes-parallel-with-the-nozzle do have less parasitic drag, but they need larger actuators to move, and, critically, don't provide roll control. They are also more difficult to fabricate.

space storability:

We have some data on a slightly different mixed monoprop storage from a Becco report in the 50's that showed it to be in the same general range as normal peroxide, which is obviously better than LOX, but not in the same store-forever class as hydrazine and such. Several months wouldn't be a problem, but years would be.

lunar lander:

We would need a star / planet tracker to keep the gyros from drifting, and we would have to use a radar or laser altimeter for terminal descent.

big engine configuration:

We may be forced to build a new one if the current one is burned. We'll see on Saturday. Even if it is still OK, we will be putting a new one together in a couple weeks to test out a new nozzle design. The next scale up will be determined based on large strategic decisions -- 24" if we want to go for a single person space shot vehicle, 36" if we want to go straight to a three person vehicle. The 24" one could also cary three people if we could recover with a parachute instead of powered landing.

longevity:

We have a good idea now what burns the engines, so we hope to put a solid 20 runs on the next fresh engine we build. We have a couple things that may improve longevity if we need to.

horizontal translations:

There is a temptation to exactly repeat the DC-X flight profiles, but it isn't part of our strategic plan right now. We are focusing on being an elevator.

design-as-we-go:
If the consumables get too expensive or the complexity too great to continue doing incremental experiment and test, we have botched the design.

minimum marginal costs:
Lox / liquified natural gas is probably the cheapest propellant combination, in the neighborhood of five cents a pound in large quantities. Our current propellant is $1/lb, but we can cut that in half or more in large quantities. In a ship jammed full of people, you might only need three pounds of propellant per pound of people, so the propellant cost might only be $30 for the trip. With airline like operations, that might mean a $100 ticket. There won't be enough demand for going straight up and down (unless we get a rotovator...) to ever get that cheap, but point-to-point suborbital could conceivably compete with conventional airlines. Without the X-Prize as a goad, we would be focusing on single person vehicles instead of trying to scale up for "economies".

roll control:
It is actually important for us to abort if we can't control the roll, because otherwise it can be claimed that the vehicle could spin up and be spin stabilized, allowing a significant downrange distance if the valves all failed open (this is the way the people granting licenses think about failures).

near ground operations:
We would just tether it, rather than trying to get a waiver. In granting a waiver, they look at worst case behavior, so it wouldn't matter if we intended it to only stay five feet off the ground.

Aldridge report:
I haven't had time to read it. Honestly, NASA isn't all that relevant to us.


John Carmack


Back to top
Profile WWW
Spaceflight Enthusiast
Spaceflight Enthusiast
avatar
Joined: Fri Jun 18, 2004 2:19 am
Posts: 2
Location: UK
Post Big Engine fuel flow control   Posted on: Fri Jun 18, 2004 2:46 am
Just a thought, for what it's worth... (I'm pretty new to this)

On a larger engine with higher max. fuel flow a single-valve may be
difficult to control at low thrust levels. A possible improvement in control
(at the expence of more hardware) would be to divide the problem
binary-style: e.g. a 1/3-bore valve plus a 2/3-bore valve.

Congratulations on your first of many Perfect Test Flights !

Yours,
Tony Wilk


Back to top
Profile WWW
Rocket Constructor
Rocket Constructor
User avatar
Joined: Wed Jun 16, 2004 7:57 pm
Posts: 8
Post    Posted on: Fri Jun 18, 2004 3:50 am
<< 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? >>

John already answered this for the mostpart. FAA AST advised us verbally this week that our 120-second burntime waiver is to be granted. We should have the official document in our grubby little hands within a couple of weeks after the legal beagles have parsed the wording.
The waiver is specific to one vehicle, the boilerplate large tube vehicle, and one location, Southwest Regional Spaceport in NM. Within this burntime and the amateur rocketry total impulse limit of 200,000 lb secs (ballistic coefficient is never a problem) we can do virtually anything we want. The limiting constraint is one of safety. As John alluded to, the FAA AST looks at the absolute worst case scenario no matter how extreme, unlikely or absurd it may be. In our case it is what we have termed, MDAIC WCFM MEF - "Multiple Demons Acting In Concert" "Worst Case Failure Mode" "Maximum Energy Footprint" Basically demonic entities take over all of the critical ACS systems and sub-systems and conspire to enable a full power gravity turn with an aerodynamically unstable vehicle. In that case we can actually reach out and touch someone about 5-miles down range. Max altitude is also a consideration but at just over 2-miles high we are unlikely to scare any passing aircraft unless they are stupid enough to wander inside the White Sands Missile Range controlled airspace (not recommended with all the Patriots they test out there!)
For the purposes of our waivered flights we will have to ensure we have a target free recovery area with a 5-mile radius. SWRS meets that requirment and also has a baseline EIS (environmental impact study) that was used by AST to ensure we don't make a mess either. However, the waiver constraints combined will still permit us flights with full thrust burn times of 60-seconds with a 3000 lb wet dress weight vehicle. Now THAT is going to be really cool!

Neil MIlburn


Back to top
Profile
Spaceflight Trainee
Spaceflight Trainee
avatar
Joined: Sat Jul 26, 2003 10:19 pm
Posts: 36
Location: Portland, OR
Post    Posted on: Fri Jun 18, 2004 4:48 am
Hey Neil (& John) -- Thanks for the great replies. Next question: by "boilerplate large tube vehicle," do you mean the one that you flew last Tuesday, or the big honker that you were doing drop tests on a while back?


Back to top
Profile
Spaceflight Enthusiast
Spaceflight Enthusiast
avatar
Joined: Fri Jun 18, 2004 4:25 am
Posts: 1
Post Visitors?   Posted on: Fri Jun 18, 2004 4:56 am
Congratulations on your recent success. I've been following the weekly updates for a couple years now, and it's great to finally see a breakthrough like this.

I had considered doing some serious research, and trying to get a good view of your test flight when I heard you were going to have one. Now I wish I had. What are your feelings on visitors for the flight this coming Tuesday?

Also, I'll be attending Quakecon again this year. Will you be giving your usual talk? I'm sure most of us would appreciate a serious, detailed overview of the work Armadillo Aersopace has been doing.


Back to top
Profile
Spaceflight Participant
Spaceflight Participant
avatar
Joined: Fri Jul 25, 2003 9:52 am
Posts: 77
Location: Estonia
Post    Posted on: Fri Jun 18, 2004 10:42 am
Bulldog wrote:
MDAIC WCFM MEF - "Multiple Demons Acting In Concert" "Worst Case Failure Mode" "Maximum Energy Footprint"

OT: simply put, DOOM :P


Back to top
Profile
Spaceflight Enthusiast
Spaceflight Enthusiast
User avatar
Joined: Fri Jun 18, 2004 12:20 pm
Posts: 2
Post    Posted on: Fri Jun 18, 2004 12:39 pm
Congratulations on this beautiful flight. With the clear exhaust and all that it really reminds me of the DC-X. The most amazing thing for me was that the vehicle did not tip over after landing.

A few questions:

1. What is the tipover angle / center of gravity of this vehicle?

I assume that the engine and actuators are very heavy, so the unfueled CG should be way down. But still it looks incredibly unstable sitting on this tiny base. I noticed that you did not even bother to put the dampers/landing gear as far out as possible.

What would be the consequences of the vehicle tipping over? Oh well, you will probably find this out soon enough.

2. What about the vehicle sitting in the sun for a few hours? I am not that much concerned about the propellant mixture itself, since it contains enough water to be reasonably safe.

But what about the gases above the propellant? When the vehicle sits in the sun for a few hours with some residual fuel, you will probably get a high pressure mixture of oxygen and gaseous methanol above the propellants. Your propellant tank is not made of metal, so you might also get some static electricity. A little static discharge, and boom, there goes your vehicle...

Do you think this risk is manageable, or do you avoid it by purging with nitrogen and not letting the vehicle sit around partially fueled?

3. What about propellant sloshing? Have you got some slosh baffles , or are you just trying to fly so smooth that the propellant does not get in motion?

4. If your propellant mixture is indeed reasonably safe, it will probably become the favorite propellant for all advanced hobbyist rocketeers. Do you have a name for it? Armadillo juice, or maybe flaming armadillo?

best regards

Rüdiger Klaehn


Back to top
Profile WWW
Rocket Constructor
Rocket Constructor
User avatar
Joined: Wed Jun 16, 2004 7:57 pm
Posts: 8
Post    Posted on: Fri Jun 18, 2004 2:12 pm
skybum wrote:
Hey Neil (& John) -- Thanks for the great replies. Next question: by "boilerplate large tube vehicle," do you mean the one that you flew last Tuesday, or the big honker that you were doing drop tests on a while back?


The boilerplate is our first large vehicle, 5-ft diameter. We did use the nosecone assembly for drop tests many moons ago. This will be the test bed for the waivered flight campaign in NM. The small tube vehicle is the 2-ft diameter beastie that we hopped on June 16.

This progression follows the Carmack / Armadillo philosophy of testing small, cheap and quick. You would be amazed at how quickly Armadillo can convert an idea into flying / testable hardware. Just do it!

Neil M


Back to top
Profile
Rocket Constructor
Rocket Constructor
avatar
Joined: Fri Jun 18, 2004 2:10 pm
Posts: 7
Post    Posted on: Fri Jun 18, 2004 2:32 pm
John,

I'd like to add my voice to the chorus of rocket fans following your progress with eager anticipation. Your regular, detailed accounts of the ups and downs (pardon the pun) of launch testing and development are greatly appreciated. I'm sure everyone reading them gets a small sense of being there.

The more I learn about the use of H2O2 for rocket flight, the more I wonder what's going on in your rocket engines. I've seen the videos of various motor tests, and don't see the same "exhaust" in the plume from your test vehicles.

Is there a link you can give to a Project Update that gives the background or the theory on what you are doing with your H2O2 engine that improves the ISP to the point where it is useful for sub-orbital/orbital launches? I'd really like to know more about the rocket engine physics/theory behind the ColdPack/Hot Pack/Combustion Chamber/Flameholder combination.

Thanks again and Good Luck!


Back to top
Profile
Spaceflight Trainee
Spaceflight Trainee
avatar
Joined: Thu Jun 17, 2004 12:44 pm
Posts: 34
Location: UK
Post Altimeter & safety   Posted on: Fri Jun 18, 2004 6:15 pm
Do you intend to use a laser or radar altimter to overcome GPS inaccuracy in vertical axis? (Would also rpovide some redundancy in case of GPS failure).
The Acuity AR4000 is one example, see
http://www.acuityresearch.com/products/ ... ndex.shtml

How do you sense 'touch-down' ATM - from vertical rate?

In manned vehicles, how do you intend ensure crew safety if the engine fails (seems a critical single-point failure). The crew could bail-out & use personal parachutes, but that wont work at low altitudes (not enough time).
Fitting parachutes to vehicle is probably out as you'd be back against range safety contraints due to wind drift. Maybe crush-zones and/or air-bags on the tail?

Good luck with big vehicle!


Back to top
Profile
Spaceflight Enthusiast
Spaceflight Enthusiast
avatar
Joined: Tue Jun 08, 2004 11:58 pm
Posts: 4
Post    Posted on: Sat Jun 19, 2004 6:29 am
Can you point out a good resource on the net that might show how your engines work?

_________________
We fight, get beat, rise and fight again."
- Major General Nathaniel Greene


Back to top
Profile
Spaceflight Enthusiast
Spaceflight Enthusiast
avatar
Joined: Fri Jun 18, 2004 2:19 am
Posts: 2
Location: UK
Post Re: Altimeter & safety   Posted on: Sat Jun 19, 2004 1:41 pm
Alex A wrote:
In manned vehicles, how do you intend ensure crew safety if the engine fails (seems a critical single-point failure). The crew could bail-out & use personal parachutes, but that wont work at low altitudes (not enough time).


It may be possible to fit a ballistic 'chute system, these can be effective
at quite low altitudes. I assume drift is not a major consideration for an
emergency life-saving system.
e.g. http://brsparachutes.com/PI_modeltypes.mgi?container=Cirrus

Yours,
Tony Wilk


Back to top
Profile WWW
Space Walker
Space Walker
User avatar
Joined: Sun Sep 28, 2003 5:34 am
Posts: 126
Location: Phoenix, AZ
Post    Posted on: Sat Jun 19, 2004 10:25 pm
Wow! It looks like I picked the wrong week to be out of the loop for seven days! This last week it seems like there have been more X Prize developments than in the last three months. Anyway, back onto the topic.

I can't say enough how great what you guys are doing is. I feel kind of sheepish after what I've said elswhere about Armadillo not living up to all the hype they get, but much, much more strongly than that I feel that every group involved in opening the space frontier should be supported vigorously, and after that flight earlier this week you guys defenately deserve a round of applause. Thanks for all that you're doing to help get the door to space open for us non-astronauts. Here are just a few questions I had:

1. Are you planing on putting any kind of abort system on your X Prize rocket or any subsequent developments of it?

2. Once the development of the X Prize capible vehicle is complete, do you plan on marketing it commercially, for microgravity payloads or microsattelites?

3. It seems that, barring a crash, Scaled or maybe DaVinci are assured to win the X Prize. What goals do you plan on pursuing after the prize is won? I looked at one of the old updates from right after SS1 was revealed and you mention several changes to the vehicle that would be made if Rutan bags the X Prize, bipropellant engines, a powered landing system, and scaling down to a single-seat format. All of those changes have now been made except scaling down the rocket, might this happen in the near future? I also dug up an old popsci in which Neil Milburn says "We want to put someone into orbit. our next step after that is to put someone on the Moon." That was said a year ago, so have the plans changed since?

4. This is going even farther out on a limb, but if you do plan on keeping the VTVL powered format for an SSTO vehicle would it be able to reach orbit? I did a few (very) rough calculations using the rocket equation I found in "The Case For Mars" and if the numbers are right a rocket with a specific impulse of 375 seconds (rough range for LOX/LCH4 engines) would need to be 92% fuel to reach orbit. Needless to say, that would be a challenge to fabricate, but it might be possible. Have you even been planing out this far? I understand if they're very rough, but I'd sure be interested to find out what your plans are for the future.

_________________
"Yes, that series of words I just said made perfect sense!"
-Professor Hubert Farnsworth


Back to top
Profile WWW
Spaceflight Trainee
Spaceflight Trainee
avatar
Joined: Fri Jan 09, 2004 1:07 am
Posts: 29
Post Need more talent - try your fans   Posted on: Sat Jun 19, 2004 11:02 pm
Dear John and Armdillo team,

First, just add my name to the Armadillo fan club list - excellent test flights, love the updates, and ditto most of the above posts.

Two questions:
1. Do you have any plans to grow your team?

Granted, most breakthroughs come from small teams such as yours, and you probably don't want to get into the nightmare of managing a large group. Also, the Armadillo team is already quite talented.

Still, there seems to be a lot of untapped goodwill in your fans, and I'd bet there's a least a few of them who have both the time and expertise to help you out - particularly with respect to the human factors issues such as cabin design, onboard controls, life support, etc. which you haven't been focused on. There's also a surfeit of engineering talent that could maybe run some analysis remotely to compliment your trial and error approach and maybe save a few trips down dead ends.

2. What future business model do you forsee for your group?

Do you plan to be the open source shop of rocketry disseminating ideas freely? Start a company to harvest your technology? And how will you prevent someone who follows your progress from ripping off your ideas, filing patents before you, and then charging you royalties to fly given your openness? This would truly bite, but I'm almost positive that you've already taken steps to prevent this. If not, maybe you have a fan that's also a patent lawyer - see #1. As you know, patents are very different from copyrighting, and more expensive and difficult to apply.

Good luck!


Back to top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2523 posts ] 
Go to page Previous  1, 2, 3, 4, 5, 6, 7 ... 169  Next

Who is online 

Users browsing this forum: No registered users and 17 guests


© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use