On Mon, 18 Nov 2002 04:53:51 +, Ian Woollard
<[EMAIL PROTECTED]> wrote:
>>>The ghost of Max Hunter says you tested it too rigorously. :-)
>>>
>>>(Several Thors failed due to excessive static testing before launch, and
>>>the static tests never once caught anything important. Eventually they
>
On Sun, 17 Nov 2002 21:28:17 -0800, Pierce Nichols
<[EMAIL PROTECTED]> wrote:
> Then it's got to be spurious. The only thing that could make
>negative G during the ascent is drag.
Of the whole vehicle, this is true. Vibration can spoof an
accelerometer, though, and I think Dave W thinks
At 12:14 AM 11/18/2002 -0800, Randall Clague wrote:
On Sun, 17 Nov 2002 21:28:17 -0800, Pierce Nichols
<[EMAIL PROTECTED]> wrote:
> Then it's got to be spurious. The only thing that could make
>negative G during the ascent is drag.
Of the whole vehicle, this is true. Vibration can spoof
In the A/D world, there is something called the Nyquist criteria - you
need to sample at least 2x the highest frequency you expect to see, to
be able to accurately 'see' the analog signal from the digital data.
Therefore, it's smart to use a lowpass filter with an edge at 1/2 your
sampling frequ
Pierce Nichols wrote:
> The second is a spurious peak resulting
> from the frequency of the chugging exceeding half the sampling rate of the
> A/D converter (i.e. undersampling). I like this one even less, b/c it is my
> understanding that spurious results from undersampling appear only if you
> i
At 03:52 AM 11/18/2002 -0500, you wrote:
In the A/D world, there is something called the Nyquist criteria - you
need to sample at least 2x the highest frequency you expect to see, to
be able to accurately 'see' the analog signal from the digital data.
Therefore, it's smart to use a lowpass filter
John Carmack wrote:
> Note that your A/D is probably sampling faster than the sensor bandwidth,
> which is usually 100hz or less for DC reading (non-vibration)
> accelerometers, so aliasing is not likely the problem. I would suspect
> flexing structure, unless you are using one of the really cheap
At 02:22 PM 11/18/2002 +1100, you wrote:
you guys are just using the raw IMU data for position information?
even a simple kalman filter or dogified version of it might have helped
reduce the problems you had (though the solutions you propose are by far a
better way of doing things. (Solving the pr
At 01:15 AM 11/18/2002 -0800, David Weinshenker wrote:
Pierce Nichols wrote:
> The second is a spurious peak resulting
> from the frequency of the chugging exceeding half the sampling rate of the
> A/D converter (i.e. undersampling). I like this one even less, b/c it is my
> understanding that sp
On Sun, 17 Nov 2002, Pierce Nichols wrote:
> >No. Download the text file; it really does show 5 g +/- 10 g. Drag
> >never gets above 2 g as long as we're subsonic.
>
> Then it's got to be spurious. The only thing that could make
> negative G during the ascent is drag.
It is physically
I think that was an amazing flight. No tower, it just jumped into the
sky. Could you detect any damage from that aluminum ground protection
plate smacking the back of the cone on lift off?
Also In the video who was the person standing in the field? The
machine seemed to arc right over their he
Alex Fraser wrote:
I think that was an amazing flight. No tower, it just jumped into the
sky. Could you detect any damage from that aluminum ground protection
plate smacking the back of the cone on lift off?
Also In the video who was the person standing in the field? The
machine seemed to arc
Randall Clague wrote:
The chug frequency wasn't constant; we heard it changing pitch.
That could be explained by doppler, since the vehicle approaches mach
one in just a few seconds, the chug rate would appear to drop even if it
were constant.
I think for reduction purposes we can assume the
Was this rocket testing a constant pressure feed?
Doug Jones wrote:
> Randall Clague wrote:
>
> > The chug frequency wasn't constant; we heard it changing pitch.
>
> That could be explained by doppler, since the vehicle approaches mach
> one in just a few seconds, the chug rate would appear to dr
Pierce Nichols wrote:
> I'm not sure how you are going to get better than the new data
> aquisition system. IIRC, it's 20 kHz per channel, and therefore
> should record anything you can see on the scope, and most of the
> audible range.
I've run the Omega DAQ-802 at 40 kS/s on a single channel, a
On Sun, 17 Nov 2002, Randall Clague wrote:
> >The ghost of Max Hunter says you tested it too rigorously. :-)
> >(Several Thors failed due to excessive static testing before launch...
>
> You're kidding, right? Thor was an ELV. Armadillo's building an RLV.
Some of the same principles apply, and
The next meeting of the Experimental Rocket Propulsion Society will be
held this THURSDAY evening at the IHOP starting at 8:00pm.
Items for meeting #249 (21 Nov 2002):
- Admin Teams
- CMT
- Documentation
- IT
- Liaisons
- Logistics
- PAO
-
>>However, if you do have some sacrificial hardware, and
can think of a
>>cheap way of shaking it to see what comes lose, and have
the hours to spare,
>>I think it would be in the direction of goodness to shake
it. If you're
>>already flying something, high resolution accelerometer
dat
On Mon, 18 Nov 2002 07:56:44 -0800, Doug Jones <[EMAIL PROTECTED]>
wrote:
>> The chug frequency wasn't constant; we heard it changing pitch.
>
>That could be explained by doppler, since the vehicle approaches mach
>one in just a few seconds, the chug rate would appear to drop even if it
>were co
On Mon, 18 Nov 2002 11:41:33 -0500, Alex Fraser <[EMAIL PROTECTED]>
wrote:
>Was this rocket testing a constant pressure feed?
Yep. Worked, too. The acceleration trace, which on KISS II showed a
decline as the tank blew down, shows a flat 5 g. Acceleration should
have increased as the vehicle g
On Mon, 18 Nov 2002 12:13:08 -0600, Rick Eversole <[EMAIL PROTECTED]>
wrote:
>I-beam -> hammer/weight -> cam -> motor
> why that expensive ... sounds like something
> for junkyard wars ...
That expensive, because you have to put it in an altitude chamber to
completely simulate the environment
The ADSL150 has a -3db bandwidth of 1kHz, so aliasing in the A to D is
quite possible. As a matter of fact, this has been a topic of discussion
on the RDAS list.
-Dave McCue
On Mon, 18 Nov 2002, David Weinshenker wrote:
> John Carmack wrote:
> > Note that your A/D is probably sampling faster tha
On Sun, 17 Nov 2002, John Carmack wrote:
> video and gory details.
> http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=182
"The important thing is that the Crossbow IMU survived, because
that costs more than everything else put together, and can have an
8 week lead t
Randall Clague wrote:
On Mon, 18 Nov 2002 12:13:08 -0600, Rick Eversole <[EMAIL PROTECTED]>
wrote:
I-beam -> hammer/weight -> cam -> motor
why that expensive ... sounds like something
for junkyard wars ...
That expensive, because you have to put it in an altitude chamber to
completely simula
The vacuum only needs to be drawn down a little bit -- our
vehicles simply don't go that high. We have the pump, and the chamber just
doesn't need to be that tight.
-p
At 07:14 PM 11/18/2002 -0800, Donald Qualls wrote:
Randall Clague wrote:
On Mon, 18 Nov 2002 12:13:08 -0600,
Could valve chatter have caused the chugging? There is an upstream
pressure change due to acceleration of the fuel. Can you describe the
system? Is there a drawing?
Randall Clague wrote:
> On Mon, 18 Nov 2002 11:41:33 -0500, Alex Fraser <[EMAIL PROTECTED]>
> wrote:
>
> >Was this rocket testing
At 10:32 PM 11/18/2002 -0500, Alex Fraser wrote:
Could valve chatter have caused the chugging? There is an upstream
pressure change due to acceleration of the fuel. Can you describe the
system? Is there a drawing?
It's a ball valve in a straight piece of pipe. Ball valves do not
chat
On Mon, 18 Nov 2002 19:14:58 -0800, Donald Qualls
<[EMAIL PROTECTED]> wrote:
>Nonsense. You can just as readily put a much smaller altitude chamber
>on the testing arm -- at the very least, at the end of the main
>centrifuge, with the smaller vibration generator inside it, but it
>shouldn't be
At 07:37 PM 11/18/2002 -0800, you wrote:
At 10:32 PM 11/18/2002 -0500, Alex Fraser wrote:
Could valve chatter have caused the chugging? There is an upstream
pressure change due to acceleration of the fuel. Can you describe the
system? Is there a drawing?
It's a ball valve in a straig
We saw the same thing during blowdown on the KISS2 flights, so its
not the regulator.
Dan
In a message dated 11/18/02 7:46:48 PM, [EMAIL PROTECTED] writes:
<< The pressure regulator might. >>
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At 11:03 PM 11/18/2002 -0500, you wrote:
We saw the same thing during blowdown on the KISS2 flights, so its
not the regulator.
Dan
In that case, it might very well be the foam catalyst pack. I could easily
see 5G acceleration opening and closing pores.
John Carmack
_
Not sure what you mean. Can you elaborate?
Dan
In a message dated 11/18/02 8:14:21 PM, [EMAIL PROTECTED] writes:
<< In that case, it might very well be the foam catalyst pack. I could
easily
see 5G acceleration opening and closing pores. >>
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At 11:20 PM 11/18/2002 -0500, you wrote:
Not sure what you mean. Can you elaborate?
Dan
In a message dated 11/18/02 8:14:21 PM, [EMAIL PROTECTED] writes:
<< In that case, it might very well be the foam catalyst pack. I could
easily
see 5G acceleration opening and closing pores. >>
The relat
John Carmack wrote:
>
> At 11:20 PM 11/18/2002 -0500, you wrote:
> >Not sure what you mean. Can you elaborate?
> >
> >Dan
> >
> >In a message dated 11/18/02 8:14:21 PM, [EMAIL PROTECTED] writes:
> >
> ><< In that case, it might very well be the foam catalyst pack. I could
> >easily
> >see 5G acc
In a message dated 11/18/02 8:33:25 PM, [EMAIL PROTECTED] writes:
<< The relatively loosely packed foam discs are probably the element of the
system most easily impacted by dynamic effects.
Have you fired the engine in the vehicle with it restrained, and had it run
smooth there, only to run ro
Randall has described this chugging as different than that heard at
other times, he mentions a recurring pattern like an ascending scale.
Some have attributed this to movement affecting the observation, doppler
effect. The electronic data is apparently not trusted for various
reasons.
I wou
Alex Fraser wrote:
> I would guess it comes down to another flight. I would think it
> would still be a KISS III flight? KISS IIIb?
Dang, Alex, you're more fixated
on our project/vehicle nomenclature
than we are!
-dave w
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