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Re: Re: Arcjet Motor


No one is disparaging MBB motors.  The problem
on AO-40 is,as it has been with all of the
Phase III birds, with the associated systems
feeding or controlling the motor.  The systems
are of our  design and lack of testing or
proper procedures has killed us in every case.
To the best of our knowledge, the MBB motor
has always performed as specified by the
manufacturer. The ineptitude is ours,  not MBB's.

We should indeed not limit ourselves to LEO
but should be smarter about what it is we can
do and can't do well.   I have great hopes for
the forward looking experiments with the
Arcjet motor.   If we need a larger kick we
should use the much less complex solid kick
motors ( <if>  we can acquire one).  If we get
into the right orbit (high enough perigee) then
we can certainly use only small thrust (arcjet,
plasma, ion, etc.) motors to our great advantage.
It is disappointing in the extreme that we have to
accelerate all that dead fuel and oxidizer, but as
Kayser says, defecation happens.

These smaller thrust motors, we can test extensively,
even in a vacuum.


----- Original Message -----
From: "Jean Gruau F8ZS" <jean.gruau@noos.fr>
To: <amsat-bb@AMSAT.Org>; "Edward R. Cole" <al7eb@ptialaska.net>
Sent: Saturday, June 09, 2001 5:57 AM
Subject: Re: [amsat-bb] Re: Arcjet Motor

> Hello Ed, Domenico, and all,
>  just my two cents for the historians and to restaure some truth.
> FIRST I have been responsible for the launch of the two german-french
> symphonie satellites and I followed with deep attention the development of
> the Europa I/II rockets.(and finally baught launches by Thor Delta from Mc
> Donnell Douglas  hi!). The 400 N  motor was built by MBB, a company
> Messerschmit, Bolkows and Blumm and was used as vernier adjustments of the
> second stage burning UDMH and N2O4. We had NEVER problem with this motor!
> The 400 N motor was also used on board of Symphonie as orbit control. We
> NEVER problem with this motor.
> SECUND I have been responsible for the definition of the Ariane program
> for the control and authorization for flight of the Ariane mark 1 and 2/3
> from number 1 (called LO1) to number 17 (called V17). So I felt fully
> responsible to have splashed Phase III A, not so far from Kourou. It was
> Ariane mark 1 and not 4.  So we never knew how should have worked the
> Thiokol motor ( I think it was burning polybutadiene by ammonium
> with a drop of aluminium powder to accelerate the combustion) but this
> had a long serie of successes. I helped Karl to obtain a place on LO6, for
> AO 10, and we got a problem at separation : contact between an antenna and
> the "Sylda" mecanical cylinder for dual launches. Then the satellite got
> inverse sense of spin and got very cold until Karl rewright the attitude
> control program, and loaded it thru telecommand. This very low temperature
> caused a leak of the pessurising gaz( don't remember helium or nitrogen)
> it has been impossible to give the last pulse for final orbit. Here again
> had NO problem with the motor itself. Do not remember any problem with
> THIRD and last, for Arsene (my project !!)we have developped (in an
> industrial frame,for training of students, and free for the project) a
> special solid kick motor called "the MARS motor", which fullfilled its
> at the first firing at sea level so that we went directly into orbit and
> our final orbit in one shot only. The speed increase was also about 1500
> m/s, fired at apogee of GTO.
> So I hope you will understand that we have not to restrict our dreams for
> future to only LEO easy satellites !!
> Best 73
> Jean-Edmond F8ZS
> ----- Original Message -----
> From: "Edward R. Cole" <al7eb@ptialaska.net>
> To: <amsat-bb@AMSAT.Org>
> Sent: Wednesday, June 06, 2001 7:36 AM
> Subject: Re: [amsat-bb] Re: Arcjet Motor
> > >From: "i8cvs" <domenico.i8cvs@tin.it>
> > >Ed and all:
> > >
> > >The ArcJect thruster is about 100 mN,giving an acceleration of order
> > > 0,0002 m/s^2 provided the ammonia is heated by electric arc, then
> > >the heated gas is expanded via a nozzle and thermal energy is converted
> > >into kinetic energy.
> > >Is AO40 there is ammonia for about 500 hours of operation offering a
> total
> > >delta-V
> > >of up to 470 m/s
> > >
> > >On the other side, 400 Newton is the nominal thrust of the rocket
> > >propellant motor.
> > >Since spacecraft launch mass is 632 Kg,the motor,if no problems
> occurred,was
> > >able to  impart an initial acceleration of typ,400/632 = 0,6m/s^2 or
> about
> > >0,06 g.
> > >Total delta-V available is about 1100 m/s
> > >
> > >The 100 mN thrust of ArcJect motor is 1/4000 of the main motor,but can
> fire
> > >for long periods,giving significant velocity changes.
> > >
> > > The kick motor used on AMSAT Phase III-A was a solid propellant
> > >345-12 containing approximately 35 kg of a mixture of powdered aluminum
> and
> > >organic chemicals in a spherical shell with a single exit nozzle.
> > >The unit was capable of producing a velocity change of about 1600 m/s
> > >during its single 20 second burn but unfortunately this AMSAT Phase
> > >satellite was lost in the Atlantic with ARIANE-4
> > >
> > >OSCAR-10 and 13  used a liquid-fuel roket produced by the German
> > >Messerschmitt .
> > >This unit produces a thrust of 400 Newton  with the advantage to be
> ignited
> > >several time and is similar to that used on AO40
> > >
> > >All tree satellites OSCAR-10,13 and AO40 had problems with the 400 N
> liquid
> > >propellant motor and no one of it was able to reach the final orbit
> > >inclination.
> > >
> > >I hope this information is usefull for the ArcJect Motor forum.
> > >
> > >73 de i8CVS Domenico
> >
> > Domenico,
> >
> > Thanks.  I had not read anything specific on the engines for AO-40, so
> > talking in generalities.  Its very interesting that the arc-jet can
> achieve
> > roughly one third of the velocity change of that of the chemical engine.
> I
> > would not have expected this, though I understand about low-thrust being
> > additive over time.  Apparently there is substantial fuel for the
> >
> > Regarding the liquid fuel history, that too is interesting, and sheds
> > light on previous comments.
> >
> > Ed
> >
> >
> >
> >
> > ----
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> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> ----
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