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CX2SA > SATDIG 24.09.13 07:24l 1085 Lines 39387 Bytes #999 (0) @ WW
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Today's Topics:
1. Re: Kick motors on Oscars: How does attitude controlwork?
(Peter Guelzow)
2. Re: Kick motors on Oscars: How does attitude control work?
(Burns Fisher)
3. 50+ Years Of Space Exploration (B J)
4. Re: Phase 3 (Robert McGwier)
5. Re: SatPC32 Registration (Alan)
6. Re: SatPC32 Registration (Martha)
7. Story About Buran (B J)
8. Re: Phase 3 (Paul Stoetzer)
9. Re: Kick motors on Oscars: How does attitude control work?
(Bryce Salmi)
10. Odd Question (MICHAEL)
11. Re: Odd Question (Jim Jerzycke)
12. Re: Odd Question (Bryce Salmi)
----------------------------------------------------------------------
Message: 1
Date: Mon, 23 Sep 2013 21:19:14 +0200
From: Peter Guelzow <peter.guelzow@xxxxxx.xx>
To: i8cvs <domenico.i8cvs@xxx.xx>
Cc: Amsat - BBs <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
controlwork?
Message-ID: <52409432.2050504@xxxxxx.xx>
Content-Type: text/plain; charset=ISO-8859-1
Hi Domenico,
Yes, AO-40 is equipped with magnetically suspended reaction wheels for
3-Axis stabilization.
They were turned on, spun up and functioned very well, even at higher
speed...
The 3-Axis stabilization was needed to generate enough electrical power
to "hot" operate the ArcJet/EPU with fully deployed solar panels...
After the Motor incident we ended up in a nicely high apogee, but the
perigee was too low and withing a very short time AO-40 would have
burned up in the atmosphere.
For that reason it was decided not to take any further risks and run the
ArcJet "cold" to quickly raise the perigee.. this goal was successful
achieved and AO-40 was finally in a safe orbit... but this life saving
maneuver consumed all the Ammonia, if I remember correctly..
There was no immediate need to go into 3-Axis mode and to deploy the
solar cells.
I think there was more concern about what else might have got damaged
and thus I think it was decided to be more on the safe side and stay in
Spin mode..
At least we got 4 more years to operate S-Band....
73s Peter DB2OS
On 23.09.2013 08:14, i8cvs wrote:
> 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: 2
Date: Mon, 23 Sep 2013 15:46:59 -0400
From: Burns Fisher <burns@xxxxxx.xx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID:
<CABX7KxVzqjNT=Zo9XMjQqbJFT1Y6uU_LZY9GG3qZKip2XQ2-tg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Very interesting stuff. Thanks to everyone who responded. Using a model
rocket engine has occurred to me :-) I noticed that the smaller ones (A,B)
tend to peak at 10s of Newtons (presumably to get the model rocket going
fast enough to be stable after it leaves the launch rod) and then settles
down to sub-10 Newtons for the rest of the burn (a second or two). So it
is quite a whack over a short period for a small bird. I did not look up
the higher power size. It would be interesting and not too difficult to do
the math to see what kind of a perigee raise would happen if someone fired
one of these on a 3U cubesat of modest mass in GTO while it was at apogee.
Don, there is enough interesting stuff to keep me watching the list. There
is also a lot of complaining. We'd love to have you rejoin AMSAT. Fox-1,
the upcoming launch, IS an FM bird, but I hope you noticed that the last
AMSAT bird, ARRISat-1 was indeed a linear. We need to continue to learn
and experiment.
Burns, W2BFJ
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: 3
Date: Mon, 23 Sep 2013 19:50:35 +0000
From: B J <va6bmj@xxxxx.xxx>
To: amsat-bb <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] 50+ Years Of Space Exploration
Message-ID:
<CAP7QzkPeCfMXuVEe_59MN09wi8UtumhOjhneCkZ3ZDBf3yBzEw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
http://edudemic.com/wp-content/uploads/2012/08/50-years-exploration-huge.jpg
73s
Bernhard VA6BMJ@ DO33FL
------------------------------
Message: 4
Date: Mon, 23 Sep 2013 15:54:31 -0400
From: Robert McGwier <rwmcgwier@xxxxx.xxx>
To: R Oler <orbitjet@xxxxxxx.xxx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>, Angus McLeod
<amcleod@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: Phase 3
Message-ID:
<CA+K5gzeQeDJe2co+J=B8e9-snMqqfpNyiZp3-nXhBEy4zgufvw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
This I can say, for a fact, is not true. PROFESSIONALS did the fueling and
safing as was required by contractual arrangements ahead of time.
Eye witness testimony given to me says there was an argument about what to
do about the RBF plug. Extenuating circumstances, a nearly perfect storm
of them, including a "not really clear coloration" and several other
factors caused the decision to be taken not to remove it.
But one thing is absolutely clear. AMSAT personal were NOT responsible for
fueling and safing. One or more participated but in "red hand mode" as in,
if you touch, your hand will be slapped until it is red.....
http://n4hy.smugmug.com/AMSAT/AO40-Phase-3D/010-Final-Assembly/2109994_HNF8Hn#
!i=109042686&k=dShmr5K
It was NOT as clear as you make it out as you can see and it was most
decidedly not "firey red" and clear as to what to do.
Where things are clear, they were and are marked clearly:
http://ukamsat.files.wordpress.com/2013/02/ao-40.jpg
The deal is, AO-40 flew. It gave quite a long period of interesting
operation. It did not attain all of its goals and was an unbelievable
complex achievement from the birth of the concept:
http://n4hy.smugmug.com/AMSAT/AO40-Phase-3D/001-Marburg0590/2107966_HX26gC#!i=
108935294&k=ssKW2Fb&lb=1&s=A
until its death, it was and remains AMSAT (all versions and hyphens)
greatest achievement.
On Sat, Sep 21, 2013 at 10:19 PM, R Oler <orbitjet@xxxxxxx.xxx> wrote:
> The people installing them and safing them and all the other things were
> mostly not rocket scientist that is why somewhere on AO-40 there is a
> "remove before flight" what we call in the business "flag" flying RGO
>
> Sent from my iPad
>
> > On Sep 22, 2013, at 1:55 AM, "Angus McLeod" <amcleod@xxxxxxxxx.xxx>
> wrote:
> >
> > As far as I know, the kick-motors used on the Phase-3 birds were NOT
> cardboard tubes packed with homemade gunpowder. They were commercial grade
> motors obtained from the commercial aerospace industry. If I am wrong
> about this, and someone can jump in with facts, I'd be glad to hear.
> >
> >
> >> On 09/21/2013 05:48 AM, Gordon JC Pearce wrote:
> >>> On Fri, Sep 20, 2013 at 11:23:29PM +0600, R Oler wrote:
> >>> While anything is possible I will be very surprised (pleasntly) if
> there is another amateur radio satellite with a liquid propulsion system
> that is managed by any amateur group that gets a ride into any sort of HEO
> transfer orbit.Ion engines might be different but after AO-40 and its
> propulsion issues the days of amateurs playing with rocket engines on
> commercial flights I suspect is over.
> >> This is something I've often wondered about. "Oh hi, commercial rocket
> company, can we stick our homebrewed rocket into your billion dollar
> vehicle?"
> >>
> >> When people with more oil than weapons stuff some mix of chemicals into
> a tube and crimp the end shut it's called an Improvised Explosive Device.
> We're supposed to somehow convince someone to let us tack our semitested
> bomb onto their flight? I doubt they're going to go for it...
> >
> > _______________________________________________
> > 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
>
> _______________________________________________
> 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
>
--
Bob McGwier
Owner and Technical Director, Allied Communication, LLC
Professor Virginia Tech
Senior Member IEEE, Facebook: N4HYBob, ARS: N4HY
Faculty Advisor Virginia Tech Amateur Radio Assn. (K4KDJ)
------------------------------
Message: 5
Date: Mon, 23 Sep 2013 15:20:03 -0500
From: Alan <wa4sca@xxxxx.xxx>
To: "'carl creamer'" <ccreame@xxxxxxx.xxx>, <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: SatPC32 Registration
Message-ID: <26AB71ACADB846E49E92D5DD3BA5BFE0@xxxxxx>
Content-Type: text/plain; charset="iso-8859-1"
Carl,
According to the records, you ordered it late Thursday evening. As you
know, we have a tiny (1)
office staff, and the program registration process is done manually rather
than automagically. It
sometimes take a few days to process, depending on many issues. This is
mentioned on the web site.
Mondays are particularly brutal. The registration will be along shortly.
73s,
Alan
WA4SCA
AMSAT Store Stock Boy
<<>>-----Original Message-----
<<>>From: amsat-bb-bounces@xxxxx.xxx
<<>>[mailto:amsat-bb-bounces@xxxxx.xxxx On Behalf Of carl creamer
<<>>Sent: Monday, September 23, 2013 1:05 PM
<<>>To: amsat-bb@xxxxx.xxx
<<>>Subject: [amsat-bb] SatPC32 Registration
<<>>
<<>>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-NA member? Join now to support the amateur
<<>>satellite program!
<<>>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
<<>>
------------------------------
Message: 6
Date: Mon, 23 Sep 2013 16:40:34 -0400
From: Martha <martha@xxxxx.xxx>
To: Alan Biddle <APBIDDLE@xxxxxxx.xxx>
Cc: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: SatPC32 Registration
Message-ID:
<CAPk0USyP=NRo-MkkeA6yGEjTeAfL4VS+vQ_Gx66REwWgvBs+Fg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
To All - The date on the PayPal form I downloaded today was Saturday, Sept
21. I sent the password to Carl around 30 minutes ago. One day turn
around for a 1 person office is pretty good!
On Mon, Sep 23, 2013 at 4:20 PM, Alan <wa4sca@xxxxx.xxx> wrote:
> Carl,
>
> According to the records, you ordered it late Thursday evening. As you
> know, we have a tiny (1)
> office staff, and the program registration process is done manually rather
> than automagically. It
> sometimes take a few days to process, depending on many issues. This is
> mentioned on the web site.
> Mondays are particularly brutal. The registration will be along shortly.
>
> 73s,
>
> Alan
> WA4SCA
> AMSAT Store Stock Boy
>
>
>
> <<>>-----Original Message-----
> <<>>From: amsat-bb-bounces@xxxxx.xxx
> <<>>[mailto:amsat-bb-bounces@xxxxx.xxxx On Behalf Of carl creamer
> <<>>Sent: Monday, September 23, 2013 1:05 PM
> <<>>To: amsat-bb@xxxxx.xxx
> <<>>Subject: [amsat-bb] SatPC32 Registration
> <<>>
> <<>>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-NA member? Join now to support the amateur
> <<>>satellite program!
> <<>>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
> <<>>
>
>
--
73- Martha
------------------------------
Message: 7
Date: Mon, 23 Sep 2013 21:56:39 +0000
From: B J <va6bmj@xxxxx.xxx>
To: amsat-bb <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Story About Buran
Message-ID:
<CAP7QzkO_-1g-Qz0QXAzbMXOSL5iuNLbMLJ58Ai1iBgwAHSuibg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
http://arstechnica.com/science/2013/09/the-life-and-death-of-buran-the-ussr-sh
uttle-built-on-faulty-assumptions/
73s
Bernhard VA6BMJ @ DO33FL
------------------------------
Message: 8
Date: Mon, 23 Sep 2013 18:35:06 -0400
From: Paul Stoetzer <n8hm@xxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Phase 3
Message-ID:
<CABzOSOo06pZas0yDDB_ObGcLDBs3ucr1T3BWf0DumkgA-JnJaw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
I recently obtained a copy of the 1990 edition of Martin Davidoff's
Satellite Experimenters' Handbook and as I was browsing through the book, I
came across a passage on page 4-9 about the difficulties with UO-11, that's
very relevant to the ongoing debate about the lack of Phase 3 satellites:
"If there's a message here, it's that taking part in the amateur satellite
program is not for the faint-hearted. Setbacks and barriers will always be
part of the picture. And, the most rewarding successes will probably come
from employing ingenuity and tenacity to overcome the 'impossible' hurdles."
73,
Paul Stoetzer, N8HM
Washington, DC (FM18lv)
On Sun, Sep 22, 2013 at 7:17 PM, <MLengruesser@xxx.xxx> wrote:
>
>
> 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
>
>
>
>
>
>
> _______________________________________________
> 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!
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------------------------------
Message: 9
Date: Mon, 23 Sep 2013 17:13:13 -0700
From: Bryce Salmi <bstguitarist@xxxxx.xxx>
To: Burns Fisher <burns@xxxxxx.xx>
Cc: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Kick motors on Oscars: How does attitude
control work?
Message-ID:
<CAN5j0soQ9jhjiy1p+z=GGLjg9x29C2iLjco6mUht0HtRYho4Vw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Found this intersting web page:
http://www.isispace.nl/cms/index.php/projects/nks
Bryce
KBL1QC
On Mon, Sep 23, 2013 at 12:46 PM, Burns Fisher <burns@xxxxxx.xx> wrote:
> Very interesting stuff. Thanks to everyone who responded. Using a model
> rocket engine has occurred to me :-) I noticed that the smaller ones (A,B)
> tend to peak at 10s of Newtons (presumably to get the model rocket going
> fast enough to be stable after it leaves the launch rod) and then settles
> down to sub-10 Newtons for the rest of the burn (a second or two). So it
> is quite a whack over a short period for a small bird. I did not look up
> the higher power size. It would be interesting and not too difficult to do
> the math to see what kind of a perigee raise would happen if someone fired
> one of these on a 3U cubesat of modest mass in GTO while it was at apogee.
>
> Don, there is enough interesting stuff to keep me watching the list. There
> is also a lot of complaining. We'd love to have you rejoin AMSAT. Fox-1,
> the upcoming launch, IS an FM bird, but I hope you noticed that the last
> AMSAT bird, ARRISat-1 was indeed a linear. We need to continue to learn
> and experiment.
>
> Burns, W2BFJ
>
> 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.
> >
> >
> >
> _______________________________________________
> 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: 10
Date: Tue, 24 Sep 2013 00:22:57 -0400
From: MICHAEL <mikef1234@xxxx.xxx>
To: <AMSAT-BB@xxxxx.xxx>
Subject: [amsat-bb] Odd Question
Message-ID: <BLU0-SMTP89A7F55880799A4ACEC617CB2E0@xxx.xxx>
Content-Type: text/plain; charset="us-ascii"
For the longest time I have been wondering how a satellite is placed in
orbit without hitting anything else? I have seen pictures of all the stuff
circling the Earth and it just baffles me how anyone can get anything in
orbit without hitting anything. Can anyone explain this?
Mike/N8GBU
------------------------------
Message: 11
Date: Tue, 24 Sep 2013 05:04:43 +0000
From: Jim Jerzycke <kq6ea@xxxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: Odd Question
Message-ID: <52411D6B.3060203@xxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Since the path that the launch vehicle will take is very well defined
(unless something goes wrong!), and the paths of most objects that would
intersect this path can be predicted, it becomes a juggling act to get a
time when the launch vehicle will have a clear path, and your ground
assets are available.
Since it takes a certain amount of time to get the launch vehicle ready,
you work "backwards" from when you know your path will be clear on your
trajectory to determine when you start your countdown.
The launch provider I work for has several people who do nothing but
plan things like this, in coordination with USSTRATCOM, NASA, the FAA,
the European Space Agency, the Russian Space Agency, and all the other
other launch providers.
In the 9 years I've been doing my part (Communications, Range, and
Telemetry) we've only had one "external" hold, and that was caused by
NASA having to move the ISS a bit because the ISS was going to have a
close approach of some space junk.
It's called a COLA (COllision Avoidance) hold, and if everybody does
their planning properly, doesn't usually cause a problem.
One of the things considered is the ascent speed of the launch vehicle,
as it's going pretty fast during it's passage through various altitudes.
HTH!
73, Jim KQ6EA
On 09/24/2013 04:22 AM, MICHAEL wrote:
> For the longest time I have been wondering how a satellite is placed in
> orbit without hitting anything else? I have seen pictures of all the stuff
> circling the Earth and it just baffles me how anyone can get anything in
> orbit without hitting anything. Can anyone explain this?
>
> Mike/N8GBU
>
> _______________________________________________
> 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: 12
Date: Mon, 23 Sep 2013 22:16:04 -0700
From: Bryce Salmi <bstguitarist@xxxxx.xxx>
To: MICHAEL <mikef1234@xxxx.xxx>
Cc: Amsat BB <AMSAT-BB@xxxxx.xxx>
Subject: [amsat-bb] Re: Odd Question
Message-ID:
<CAN5j0srkfpT5nRF-395ViCbPmssGyG_=xs9mpbj8p-qa7FG3iw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
This is actually a great question. I've even asked it myself to some
coworkers (in the Guidance, Navigation, and Control department). When it
comes down to it, the space above Earth where satellites orbit is actually
vast. There's a heck of a lot more space than most images showing space
debris will elude to. This is largely because most of those images showing
space junk use dots to represent the pieces we know about. The problem is
that given the scale of the Earth in these images, that tiny dot is
actually MASSIVE compared to the realistic size of even a large satellite.
The truth is that while there's a large amount debris, the chance of
actually hitting anything is pretty small due to the sheer amount of space
the debris is distributed in. The images showing space debris as dots or
other icons are actually pretty poor representations of the space debris
problem (they look cool though). A probability distribution or similar is
what I would imagine as being more useful.
Bryce
KB1LQC
On Mon, Sep 23, 2013 at 9:22 PM, MICHAEL <mikef1234@xxxx.xxx> wrote:
> For the longest time I have been wondering how a satellite is placed in
> orbit without hitting anything else? I have seen pictures of all the stuff
> circling the Earth and it just baffles me how anyone can get anything in
> orbit without hitting anything. Can anyone explain this?
>
> Mike/N8GBU
>
> _______________________________________________
> 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
>
------------------------------
_______________________________________________
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 326
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