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CX2SA > SATDIG 23.09.13 21:03l 597 Lines 20567 Bytes #999 (0) @ WW
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Today's Topics:
1. Re: Gygnus Delay (Clint Bradford)
2. Kick motors on Oscars: How does attitude control work?
(Burns Fisher)
3. Re: Kick motors on Oscars: How does attitude control work?
(Peter Guelzow)
4. Re: Kick motors on Oscars: How does attitude control work?
(Daniel Schultz)
5. Re: Phase 3 (MLengruesser@xxx.xxxx
6. Re: Kick motors on Oscars: How does attitude control work?
(Samudra Haque)
7. Re: Kick motors on Oscars: How does attitude control work?
(Joe Fitzgerald)
8. Re: Kick motors on Oscars: How does attitude controlwork? (i8cvs)
9. Re: Kick motors on Oscars: How does attitude controlwork? (don)
10. k8bl road trip (k4feg)
11. Another Delay For Cygnus (B J)
12. Fw: Delfi C3 Close Approach Notification (Peter Portanova)
13. SatPC32 Registration (carl creamer)
----------------------------------------------------------------------
Message: 1
Date: Sun, 22 Sep 2013 12:19:00 -0700
From: Clint Bradford <clintbrad4d@xxxxxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: Gygnus Delay
Message-ID: <3F81B1FC-2B6F-4022-A808-5753C825063F@xxxxxxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
Cady Coleman tweeted this morning - writing that Cygnus and the ISS each
looked at their clocks, and they weren't in sync ... (grin)
Clint
------------------------------
Message: 2
Date: Sun, 22 Sep 2013 16:19:07 -0400
From: Burns Fisher <burns@xxxxxx.xx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Kick motors on Oscars: How does attitude control
work?
Message-ID:
<CABX7KxWSkVFjtzAc7iwPhSGHTQKSHaUE4WfHTA+AtQeAbVdQ5g@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
There has been a lot of discussion about AO-10, 13, and 40 (and maybe
others) with various kinds of apogee kick motors (and inclination changers
etc). Rather than fanning any flames, I just want to ask a question: If
you have a motor of a few hundred Newtons, how to you keep the attitude
stable during the burn? For that matter, how do you get the attitude
correct for the start of the burn? I would not think that electromagnets
operating against the earth's magnetic field would have enough power with
such a large motor. Obviously it depends on the balance of the satellite
relative to the position of the kick motor, but still...was the balance
really good enough to allow magnetic attitude control? Was it active (i.e.
with feedback)? Does that imply a rate gyro? (No MEMS then, I suppose).
Thanks in advance for the technical history lesson...
73,
Burns W2BFJ
------------------------------
Message: 3
Date: Sun, 22 Sep 2013 23:21:26 +0200
From: Peter Guelzow <peter.guelzow@xxxxxx.xx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID: <523F5F56.8000103@xxxxxx.xx>
Content-Type: text/plain; charset=ISO-8859-1
Hi Burns,
yes - all Phase 3 satellites use Magnetorquers to control attitude
during perigee. They were pulsed by the IHU on-board computer which was
running a model of the physics and orbital dynamics to trigger the
correct coils at the right moment. This Timing was synchronized with
the Sun sensor... indeed P3 spacecrafts are Spin stabilized...
There was no feedback. Command stations did some calculations based on
Earth and Sun sensor data, but once calibrated the system worked quite
smoothly and predictable...
For the motor burns, the attitude was indeed determined by the Sun and
Earth sensors and several times corrected until the perfect attitude was
achieved.. this took a few days.
Basically a very simple system was simple physics involved...
73s Peter
On 22.09.2013 22:19, Burns Fisher wrote:
> There has been a lot of discussion about AO-10, 13, and 40 (and maybe
> others) with various kinds of apogee kick motors (and inclination changers
> etc). Rather than fanning any flames, I just want to ask a question: If
> you have a motor of a few hundred Newtons, how to you keep the attitude
> stable during the burn? For that matter, how do you get the attitude
> correct for the start of the burn? I would not think that electromagnets
> operating against the earth's magnetic field would have enough power with
> such a large motor. Obviously it depends on the balance of the satellite
> relative to the position of the kick motor, but still...was the balance
> really good enough to allow magnetic attitude control? Was it active (i.e.
> with feedback)? Does that imply a rate gyro? (No MEMS then, I suppose).
>
> Thanks in advance for the technical history lesson...
>
> 73,
>
> Burns W2BFJ
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 4
Date: Sun, 22 Sep 2013 17:49:07 -0400
From: "Daniel Schultz" <n8fgv@xxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID: <571RiVVWH1408S06.1379886547@xxxxx.xxx.xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
>I just want to ask a question: If you have a motor of a few hundred
>Newtons, how to you keep the attitude stable during the burn? For that
>matter, how do you get the attitude correct for the start of the burn?
Simple question, simple answer: You use the magnetotorquers to point the spin
axis in the right direction, check and check again to make sure you got that
right, then use the magnetotorquers again to spin up the satellite at a high
angular rate (maybe 20 RPM). The angular momentum of the spinning satellite
keeps it stable while the motor is firing. The motor thrust must of course be
well aligned with the spin axis, but if the thrust vector is not perfect, the
spinning satellite tends to even out the small deviation.
One of the recent Cubesats carried high power model rocket engines to try an
experimental orbit adjustment. They forgot to spin the satellite and the
Cubesat tumbled wildly as a result of the motor burn. Some of these groups are
really lacking in basic physics knowledge (and we are not talking about wet
behind the ears students in that case.)
Dan Schultz N8FGV
------------------------------
Message: 5
Date: Sun, 22 Sep 2013 19:17:34 -0400 (EDT)
From: MLengruesser@xxx.xxx
To: n8fgv@xxx.xxxx amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: Phase 3
Message-ID: <825ae.6c96f8ff.3f70d48e@xxx.xxx>
Content-Type: text/plain; charset="ISO-8859-1"
Hi Dan,
OSCAR-10 (P3-B) used the same 400N engine as OSCAR-13 (P3-C) and
OSCAR-40 (P3-D).
For P3-E we have a 200N motor from EADS Astrium, the same one which is
used on the European ATV...
I was AMSAT P3-A (planned to be OSCAR-9) which used a solid propellant
apogee kick-motor.
It's under the water near the cost of french Guiana.. RIP
You can find an very good article here:
http://www.ka9q.net/AMSAT-Tech-Journal-2.pdf
See page 8..15
Rest assured, the PFA and propulsion system was qualified according to
highest commercial standards by commercial companies. Thus in no way
there would be any risk to the launcher or other payloads. This also
includes several levels of safety borders in the hardware design and in
the software. The launch agencies have there own specialized personal
to review all the details... Without that, nobody would have launched
any of the P3 satellites !!!
What happened to AO-40 later on after orbit injection and after
activating the systems is a completely different matter and did not
present any risk to the launcher at any time!
Michael R. Lengruesser, DD5ER
AMSAT-DL e.V.
-- International Satellites for Communication,
Science and Education --
mlengruesser@xxxxxxxx.xxx
http://www.amsat-dl.org
In einer eMail vom 22.09.2013 21:07:08 Westeurop?ische Sommerzeit schreibt
n8fgv@xxx.xxxx
>>The apogee motors for OSCAR-10,and OSCAR-13 were solid propellant
>>400 Newton trust motors donated to AMSAT-DL by the Messerschmitt
Aerospace
>>Company in Germany.
Only Phase 3A had a solid fuel motor. AO-10 and AO-13 had liquid fuel
bi-propellent motors the same as AO-40. No matter how well designed they
are,
they still have the potential to blow up the entire launch stack if
something
goes wrong. Since Dick Daniels is no longer with us, the knowledge has been
lost and we will not be launching any more of these in the future.
Dan Schultz N8FGV
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 6
Date: Sun, 22 Sep 2013 21:04:33 -0400
From: Samudra Haque <samudra.haque@xxxxx.xxx>
To: Daniel Schultz <n8fgv@xxx.xxx>
Cc: Amsat-bb <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID:
<CAJEM476QmDyhLMo_1rFiyen15iZO7ebRX25fLG=eHikRobF7sA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Which cubesat project ?
On Sun, Sep 22, 2013 at 5:49 PM, Daniel Schultz <n8fgv@xxx.xxx> wrote:
> >I just want to ask a question: If you have a motor of a few hundred
> >Newtons, how to you keep the attitude stable during the burn? For that
> >matter, how do you get the attitude correct for the start of the burn?
>
> Simple question, simple answer: You use the magnetotorquers to point the
> spin
> axis in the right direction, check and check again to make sure you got
> that
> right, then use the magnetotorquers again to spin up the satellite at a
> high
> angular rate (maybe 20 RPM). The angular momentum of the spinning satellite
> keeps it stable while the motor is firing. The motor thrust must of course
> be
> well aligned with the spin axis, but if the thrust vector is not perfect,
> the
> spinning satellite tends to even out the small deviation.
>
> One of the recent Cubesats carried high power model rocket engines to try
> an
> experimental orbit adjustment. They forgot to spin the satellite and the
> Cubesat tumbled wildly as a result of the motor burn. Some of these groups
> are
> really lacking in basic physics knowledge (and we are not talking about wet
> behind the ears students in that case.)
>
> Dan Schultz N8FGV
>
>
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 7
Date: Sun, 22 Sep 2013 22:22:11 -0400
From: Joe Fitzgerald <jfitzgerald@xxxx.xxx.xxx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID: <523FA5D3.3020001@xxxx.xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 9/22/2013 4:19 PM, Burns Fisher wrote:
> I would not think that electromagnets
> operating against the earth's magnetic field would have enough power with
> such a large motor.
The electromagnets had some "oomph" I seem to remember the engineering
beacon moving in frequency slightly when they switched on ... I don't
remember if it was because of a sag on the DC bus, or the magnetic field
affecting the tuned circuits of the transmitter.
But you bring up important points, if we are to do orbit adjustments,
we need to do attitude determination and control in addition to getting
a motor aboard. No easy feat in a 3U cubesat!
-Joe KM1P
------------------------------
Message: 8
Date: Mon, 23 Sep 2013 08:14:44 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "Peter Guelzow" <peter.guelzow@xxxxxx.xx>, "Amsat - BBs"
<amsat-bb@xxxxx.xxx>, "Daniel Schultz" <n8fgv@xxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
controlwork?
Message-ID: <000901ceb824$34922710$0301a8c0@xxxxx>
Content-Type: text/plain; charset="iso-8859-1"
Hi Peter,DB2OS
If I well remember in addition with the Magnetorquing ,AO40
was equipped with a 3 axis X-Y-Z stabilization wheel/EPU
acting as gyroscopes that never where used except one time
I remember to have seen on the P3T TLM the wheels were
tested rotating for a short time at a very low numbar of turns
....... or I am wrong ?
Why the 3 axis stabilization wheel/EPU whre never used on
AO40 ?
Thanks for your answere.
73" de
i8CVS Domenico
----- Original Message -----
From: "Peter Guelzow" <peter.guelzow@xxxxxx.xx>
To: <amsat-bb@xxxxx.xxx>
Sent: Sunday, September 22, 2013 11:21 PM
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
controlwork?
> Hi Burns,
>
> yes - all Phase 3 satellites use Magnetorquers to control attitude
> during perigee. They were pulsed by the IHU on-board computer which was
> running a model of the physics and orbital dynamics to trigger the
> correct coils at the right moment. This Timing was synchronized with
> the Sun sensor... indeed P3 spacecrafts are Spin stabilized...
> There was no feedback. Command stations did some calculations based on
> Earth and Sun sensor data, but once calibrated the system worked quite
> smoothly and predictable...
> For the motor burns, the attitude was indeed determined by the Sun and
> Earth sensors and several times corrected until the perfect attitude was
> achieved.. this took a few days.
> Basically a very simple system was simple physics involved...
>
> 73s Peter
>
>
> On 22.09.2013 22:19, Burns Fisher wrote:
> > There has been a lot of discussion about AO-10, 13, and 40 (and maybe
> > others) with various kinds of apogee kick motors (and inclination
> > changers etc). Rather than fanning any flames, I just want to ask a
> > question: If you have a motor of a few hundred Newtons, how to
> > you keep the attitude stable during the burn?
> > For that matter, how do you get the attitude correct for the start
> > of the burn? I would not think that electromagnets operating against
> > the earth's magnetic field would have enough power with
> > such a large motor.
> > Obviously it depends on the balance of the satellite relative to the
> > position of the kick motor, but still...was the balance really good
> > enough to allow magnetic attitude control?
> > Was it active (i.e. with feedback)? Does that imply a rate gyro?
> > (No MEMS then, I suppose).
> >
> > Thanks in advance for the technical history lesson...
> >
> > 73,
> >
> > Burns W2BFJ
------------------------------
Message: 9
Date: Mon, 23 Sep 2013 20:51:19 +1200
From: don <donmc@xxxx.xx.xx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
controlwork?
Message-ID: <52400107.9060000@xxxx.xx.xx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi,
After a long absence I decided to check out the AMSAT mailing list again.
It's been on my spam list for some time now, (mainly because of the
insane FM square collecting posts)but I thought it time to check again.
Amazingly I now find real technical discussions being carried on, is
this now normal? could some one reply to the affirmative.... I may even
find some funds to rejoin amsat if the board now reflects the
experimental and technical pursuits of real satellite enthusiasts.
Please no more FM sats. I like "beep sats" and enjoy getting data from
them.....
Don.
------------------------------
Message: 10
Date: Mon, 23 Sep 2013 07:01:39 -0500
From: k4feg <k4feg@xxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] k8bl road trip
Message-ID: <52402DA3.8050100@xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Here is the "Itinerary" for/*K*//**//*8BL's road trip starting today:*/
Be sure to listen for Bob on all satellites!
Below is the email Bob sent me:
/*Here is my plan for the week of 9/23-9/27.*/
/**/
/**//**/
/**/
/*I'll be driving around Lake Huron and activating as many of the
Grids I pass through as possible. On Monday 9/23 I'll be headed north from
Detroit and hit EN84, 85, 75, & 76, but I may make it to EN77/87 by late*/
/**/
/*afternoon depending on speed & traffic. On Tuesday 9/24 my plan is to
quickly
go through EN76 & 77 to hit rare EN87 and back down through EN77, 76
and into EN86. On Wednesday 9/25 I'll be in EN96 and go for rare EN97
and head down into EN95. Thursday 9/26 will take me through FN05, 04
and into EN94. On Friday 9/27 I expect to be in EN94, 93 & 92. All of this*/
/**/
/*is flexible based on road situations as they arise, but my goal is to
activate*/
/**/
/*as many of these Grids as possible.
By Saturday 9/28 my plan to to just dead-head back to my QTH in EN91.
Hope to work a lot of the Grid Chasers on my journey!*/
/**/
/**//**/
/**/
/*Frank, please try to get this on Starcom & AMSAT tonight if possible so*/
/**/
/*folks will know I'll be available.
Good Luck Everyone!
*/73 ALL FRM
STARCOM DIV of the GGG
K4FEG
/The Commander
GGHQ: EM55aj84ta
"...no grid left behind..."
/
------------------------------
Message: 11
Date: Mon, 23 Sep 2013 16:39:21 +0000
From: B J <va6bmj@xxxxx.xxx>
To: amsat-bb <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Another Delay For Cygnus
Message-ID:
<CAP7QzkMwo-a7xpXxEXnTbKpv=xY-vr8moE3K2P13GF=JKyOtkw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
http://www.spaceflightnow.com/antares/cots1/130922delay/#.Uj8Tl9IwkQM
http://www.parabolicarc.com/2013/09/23/cygnus-rendezvous-postponed-crew-arrriv
al/
http://www.americaspace.com/?p=42942
73s
Bernhard VA6BMJ @ DO33FL
------------------------------
Message: 12
Date: Mon, 23 Sep 2013 12:53:27 -0400
From: "Peter Portanova" <wb2oqq@xxxxxxx.xxx>
To: <AMSAT-BB@xxxxx.xxx>
Subject: [amsat-bb] Fw: Delfi C3 Close Approach Notification
Message-ID: <F9BE0C78BCAF4778A5D3B3512EFFF62F@xxxxxxx>
Content-Type: text/plain; charset="Windows-1252"
FYI
73's WB2OQQ
Sir/Ma'am,
The United States Joint Space Operations Center (JSpOC) has identified a
predicted conjunction between Delfi C3 (SCC# 32789) and SCC# 38013.
Primary Object: Delfi C3 (SCC# 32789)
Secondary Object: SCC# 38013
Time of Closest Approach: 26 SEP 2013 02:05 UTC
Overall miss distance: 796 meters
Radial (dU) miss distance: -177 meters
In-Track (dV) miss distance: 760 meters
Cross-track (dW) miss distance: -158 meters
Primary Radial Error (U): 24 meters
Primary In-track Error (V): 1443 meters
Primary Cross-track Error (W): 7 meters
Secondary Radial Error (U): 11 meters
Secondary In-track Error (V): 703 meters
Secondary Cross-track Error (W): 5 meters
Very Respectfully,
JSpOC Orbital Protection Team
Joint Space Operations Center
NO WARRANTIES: The United States provides the enclosed Space Situational
Awareness (SSA) services or information "as is" and makes no warranty,
either express or implied, as to the condition or suitability of the
information and services, nor its fitness for a particular purpose.
IMMUNITY: The United States, any agencies and instrumentalities thereof, and
any individuals, firms, corporations, and other persons acting for the
United States, shall be immune from any suit in any court for any cause of
action arising from the provision or receipt of SSA services or information,
whether or not provided in accordance with 10 USC 2274, or any related
action or omission.
------------------------------
Message: 13
Date: Mon, 23 Sep 2013 11:04:48 -0700 (PDT)
From: carl creamer <ccreame@xxxxxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] SatPC32 Registration
Message-ID:
<1379959488.9887.YahooMailNeo@xxxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
I need some advice on how to solve this.
I downloaded ?and installed SatPC32 V.12.8b a few weeks ago and got it up
and working as it should.It is a cool program.
I also ?ordered the Registration on paypal last week , but have yet to
receive the registration information email.
I sent an email and called the 1-888 number and so far no response.
Any suggestion on how to resolve this would be greatly appreciated.
Thanks
Carl
WQ6C
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 8, Issue 325
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