Keith and I both hope to be able to attend "Thunda Down Under"[1] in
2015, and I've sent the organizers email requesting information on what
it takes to be treated as an on-site vendor.
Of course, it's always more fun to be at a launch when you have something
interesting to fly! Thus, while Keith and I might each show up with a
modest "travel rocket" of some sort... I've started pondering possible
larger "Altus Metrum" group projects. Since transporting a large
airframe to Australia would be a hassle, I wonder if a group project to
build an airframe in-country makes more sense? To that end, I'd be
pleased to know if any of our friends and customers in Australia want to
sign up to help with such a project?
My thoughts would be to engage in some group-think about project scope
and goals, then hope friends in-country would take on the sourcing and
preparation of suitable airframe materials. Depending on who wants to
participate and how tasks get taken up, we might plan to arrive a bit
early to help with any final assembly or other preparations,
installation of suitably fresh Altus Metrum electronics, etc.
So, to all our Aussie friends... does this sound like fun? If so,
please chime in with a reply. I don't expect the email associated with
such a project to be too heavy a load for this list to carry, but we can
always spawn a dedicated lists.gag.com list if I'm wrong.
Regards,
Bdale
[1] http://thunda.com.au/
I just sent off to have some TeleMega PCBs and masks made and was planning
on building a few of these boards myself. I was curious if others have
assembled these by hand and what their experience was like doing so. What
reflow methods have you used (air, oven, hotplate, etc)?
Thanks,
Jared
David Carter <dcarter(a)entertain-me.com> writes:
> I had a question about building the source, and thought I’d check the
> archive. When I follow the link on the site, it says I don’t have
> permission.
Oops! You found (another) place I missed a config file semantic change
in the upgrade to Apache 2.4 a while back. Fixed now.
Bdale
Yes, I’m actually trying to do that :)
I tried checking the archives for answers, but I’m unable to access them at the moment so I apologize for any redundancies.
I’ve got most things working, but it seems to depend on a local copy of pdclib. I was able to find original source on bitbucket, but have no idea how it’s supposed to integrate and build. The altos build process expects a makefile that doesn’t exist. Any suggestions?
David Carter
dcarter(a)entertain-me.com
Web Customer <am-query(a)gag.com> writes:
Copying the list since I've had this question before and getting a
discussion going about different antenna ideas could be fun. If you
aren't already a list member, see the bottom of the altusmetrum.org page
for a link to our list server and sign yourself up!
> Comment: I have two of your TeleGPS units. Last month I attended a
> local HAM swap, which is something our Rocket club attends yearly to
> create awareness for rocketry. While there I thought I would ask
> around for a suitable “base station” antenna for my TeleGPS, which I
> had on display. Someone suggested that I could get more range from
> the antenna on the TeleGPS, because it was/is essentially only half of
> an antenna and that I simply needed to add an equivalent length size
> of wire to the ground side of the TeleGPS. Does this sound correct?
That's a gross over-simplification, and not the whole story. It is,
however, something you're likely to hear again in the ham community
where the "default" antenna for many is the 1/2-wave dipole. A 1/4 wave
whip, which is what we're providing by default on TeleGPS and our other
flight boards isn't "half an antenna", it's just an antenna built to
different design criteria.
Many books have been written about antenna design. If you're interested
in the topic, a good place to start would be the ARRL Handbook and/or
one of the antenna books from the ARRL or RSGB. Note that "conventional
wisdom" in HF space doesn't always map well to UHF, so focusing on ideas
that others have already discovered work well at 70cm could help narrow
your focus.
Antennas in rockets get complicated by a lot of things, including the
dielectric influence of airframe materials, proximity of other metal
like all-thread in ebays, etc. After trying a bunch of things, we think
the simple wire 1/4-wave whip is a pretty good choice. However, I've
done some "creative" things, like loading up the motor case as an
antenna, loading up two fins (see the 'Fintenna' heading at
http://gag.com/rockets/airframes/YikStik3/
for more details on that), and I'm currently building a 12" airframe
that will have full dipoles on 70cm mounted just inside the skin as far
From the 6" motor case as I can get them. So many choices! ;-)
> Integrated antenna aside, my original search was for a unidirectional
> antenna that I could connect to my computer sitting on my launch
> prep-table, with the antenna affixed to one of my canopy legs on an
> extension pole. I would then use my 3 element yagi with my TeleBT and
> my phone while watching and visually tracking from the launch line,
> and just leave my computer running back at my prep table, to hopefully
> capture the flight. What is the best antenna for this application?
The "problem" is that you want an antenna with good performance at high
radiation angles (since the rocket will be "up" during much of the
flight as seen from the flight line). Many sophisticated ham radio
antennas are explicitly designed to direct most energy to/from the
horizon for longer distance comms and just don't work all that well for
rockets in flight. A simple 1/4 wave over a ground plane, a patch, or a
quadrifilar helix on 70cm (or variants like the "Texas Potato Masher"
are all pretty good choices. An even better idea, but it can be harder
to arrange, is to get someone to back a mile or so off from the flight
line where they'll have a "broad side" view of the rocket through the
entire flight... that's often the best way to get all the packets, since
otherwise a ground station on the flight line is looking up at a
sub-optimal antenna radiation angle for at least the boost and coast
phases of the flight.
In any case, just experiment! The ground software shows received signal
strength for each received packet, so you can easily see what works
better and worse, and it's fun to try things!
Above all, have fun!
Bdale
Bdale,
After a lot of reading I built a crossed Moxon dipole antenna for
just the purpose described below. It was designed by L. B. Cebik (sk)
and described in the August 2001 issue of QST starting on page 38.
Don't miss the addendum in QST for October 2001 starting on page 78 for
more information on the Moxon.
The Crossed Moxon antenna has a radiation pattern with about 6 to 7
dB of gain overhead and a similar loss on the horizon. I liked the
fact that the antenna was circularly polarized since the polarity of the
received signal is unknown and random during the descent phase of the
launch.
The hardest part of the construction is building the phasing
section. It is tough to get it cut and installed into the antenna with
as short of lead lengths. I chose to place mine inside the supporting
pipe to help keep it out of the elements and to reduce the lead
lengths. I also added ferrite sleeves over the coax feed line to
reduce radiation from the feed line but this probably isn't needed.
Despite what is shown in the QST article it is important to keep
material away from the ends of the wire gaps. I found that placing
anything near the gap detuned the antenna significantly. This was
measured using a VNA.
I am using a TeleGPS in the rocket and two antennas for tracking.
The Crossed Moxon antenna and a vertical with drooping radials which
should work better at the horizon. The Moxon is connected to a TeleBT
and my cell phone. The vertical is connected to the vertical and goes
to the back up PC. Both antennas are mounted on 5 foot tall PVC pipe
tripods.
So far, only one flight, the results are mixed. There is more variation
in the RSSI of the Moxon than I expected and vertical has a steadier
signal. The Moxon does do better at apogee as expected, but not as
much as expected. This was a 3,000 foot flight so it will be
interesting to see what happens on a 10,000 foot high flight next
month. Also interesting is the difference of RSSI while the rocket is
sitting on the pad.
Terry
Thanks everyone for their feedback. I was really overthinking it. It turns
out directly connecting the switch pins on the board and moving the switch
between the battery leads and the board covers all the requirements. This
isn't how I normally fly mine so I went down quite a few rabbit holes.
Since a few folks mentioned changing NAR requirements, I've gone ahead and
contacted them for clarification. If anything comes of it I will follow-up
here.
On Fri, Apr 15, 2016 at 11:26 AM, <altusmetrum-request(a)lists.gag.com> wrote:
> Send altusmetrum mailing list submissions to
> altusmetrum(a)lists.gag.com
>
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>
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> than "Re: Contents of altusmetrum digest..."
>
>
> Today's Topics:
>
> 1. Re: altusmetrum Digest, Vol 64, Issue 1 (Sam Fineberg)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 15 Apr 2016 13:26:01 -0400
> From: Sam Fineberg <sam(a)fineberg.net>
> To: altusmetrum(a)lists.gag.com
> Subject: Re: [altusmetrum] altusmetrum Digest, Vol 64, Issue 1
> Message-ID: <57112429.2030805(a)fineberg.net>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> I wouldn't do it, its just another place to introduce points of failure,
> and I didn't for my L3. Most L3CC's just want to see wiring according
> to the altimeter manufacturer's specs.
>
> Sam
>
> On 4/15/2016 1:02 PM, Chris Attebery wrote:
> > Double check with your L3CC. I've read in several places that NAR
> > dropped that requirement. Personally I think it just adds complexity
> > and more room for human error.
> >
> > On Fri, Apr 15, 2016 at 9:52 AM, Rob Derstadt <rderstadt(a)gmail.com
> > <mailto:rderstadt@gmail.com>> wrote:
> >
> > I agree with the horizontal "safe mode" technique. It's what I use
> > now.
> >
> > The current NAR requirement states:
> >
> > "The capability must exist to externally disarm all pyrotechnic
> > devices on-board the rocket. In this context, ‘disarm’ means the
> > ability to physically break the connection between a pyrotechnic
> > system and its power source. ***Simply turning off the device
> > controlling the pyrotechnic(s) may not be sufficient.***"
> >
> > 4.
> >
> >
> > So is this really just using the other pole on the rotary switch
> > to control the battery connection?
> >
> >
> >
> > On Fri, Apr 15, 2016 at 10:37 AM,
> > <altusmetrum-request(a)lists.gag.com
> > <mailto:altusmetrum-request@lists.gag.com>> wrote:
> >
> > Send altusmetrum mailing list submissions to
> > altusmetrum(a)lists.gag.com <mailto:altusmetrum@lists.gag.com>
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > http://lists.gag.com/mailman/listinfo/altusmetrum
> > or, via email, send a message with subject or body 'help' to
> > altusmetrum-request(a)lists.gag.com
> > <mailto:altusmetrum-request@lists.gag.com>
> >
> > You can reach the person managing the list at
> > altusmetrum-owner(a)lists.gag.com
> > <mailto:altusmetrum-owner@lists.gag.com>
> >
> > When replying, please edit your Subject line so it is more
> > specific
> > than "Re: Contents of altusmetrum digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Advice on wiring dual Telemetrums for arm/safe? (Rob
> > Derstadt)
> > 2. Re: Advice on wiring dual Telemetrums for arm/safe? (w9ya)
> > 3. Re: Advice on wiring dual Telemetrums for arm/safe? (w9ya)
> > 4. Re: Advice on wiring dual Telemetrums for arm/safe?
> > (Chris Attebery)
> >
> >
> >
> ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Fri, 15 Apr 2016 09:57:17 -0600
> > From: Rob Derstadt <rderstadt(a)gmail.com
> > <mailto:rderstadt@gmail.com>>
> > To: altusmetrum(a)lists.gag.com <mailto:altusmetrum@lists.gag.com>
> > Subject: [altusmetrum] Advice on wiring dual Telemetrums for
> > arm/safe?
> > Message-ID:
> >
> > <
> CACyCNxQ1cSrDAukeyi2oBJzegyEgspFa4MD7FiNt4peziOBbew(a)mail.gmail.com
> > <mailto:
> CACyCNxQ1cSrDAukeyi2oBJzegyEgspFa4MD7FiNt4peziOBbew(a)mail.gmail.com>>
> > Content-Type: text/plain; charset="utf-8"
> >
> > Hello,
> >
> > I'm trying to work out how to wire up the outputs of two
> > Telemetrums (one
> > primary, one backup) so that I can add an extra arm/disarm
> > rotary switch
> > between the outputs and the terminal blocks (the NAR L3
> > requirement to cut
> > power completely from the pyro's).
> >
> > This is my initial wiring diagram:
> >
> >
> https://github.com/robderstadt/NAR-L3-Project/blob/master/images/plans/Gizm…
> >
> > Normally I'd just *try* it and see what happens, but I don't
> > want to fry
> > two board if I get it wrong. I'm also concerned that in the
> > "safe" position
> > that the continuity indicator on each board would still
> > indicate everything
> > green, which could lead to a launch with the pyro's inhibited.
> >
> > Has anyone flown this configuration before? If so, any
> > suggestions on how
> > to hook it up?
> >
> > Thanks guys.
> >
> > -Rob
> >
I agree with the horizontal "safe mode" technique. It's what I use now.
The current NAR requirement states:
"The capability must exist to externally disarm all pyrotechnic devices
on-board the rocket. In this context, ‘disarm’ means the ability to
physically break the connection between a pyrotechnic system and its power
source. ***Simply turning off the device controlling the pyrotechnic(s) may
not be sufficient.***"
1.
So is this really just using the other pole on the rotary switch to control
the battery connection?
On Fri, Apr 15, 2016 at 10:37 AM, <altusmetrum-request(a)lists.gag.com> wrote:
> Send altusmetrum mailing list submissions to
> altusmetrum(a)lists.gag.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.gag.com/mailman/listinfo/altusmetrum
> or, via email, send a message with subject or body 'help' to
> altusmetrum-request(a)lists.gag.com
>
> You can reach the person managing the list at
> altusmetrum-owner(a)lists.gag.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of altusmetrum digest..."
>
>
> Today's Topics:
>
> 1. Advice on wiring dual Telemetrums for arm/safe? (Rob Derstadt)
> 2. Re: Advice on wiring dual Telemetrums for arm/safe? (w9ya)
> 3. Re: Advice on wiring dual Telemetrums for arm/safe? (w9ya)
> 4. Re: Advice on wiring dual Telemetrums for arm/safe?
> (Chris Attebery)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 15 Apr 2016 09:57:17 -0600
> From: Rob Derstadt <rderstadt(a)gmail.com>
> To: altusmetrum(a)lists.gag.com
> Subject: [altusmetrum] Advice on wiring dual Telemetrums for arm/safe?
> Message-ID:
> <
> CACyCNxQ1cSrDAukeyi2oBJzegyEgspFa4MD7FiNt4peziOBbew(a)mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hello,
>
> I'm trying to work out how to wire up the outputs of two Telemetrums (one
> primary, one backup) so that I can add an extra arm/disarm rotary switch
> between the outputs and the terminal blocks (the NAR L3 requirement to cut
> power completely from the pyro's).
>
> This is my initial wiring diagram:
>
>
> https://github.com/robderstadt/NAR-L3-Project/blob/master/images/plans/Gizm…
>
> Normally I'd just *try* it and see what happens, but I don't want to fry
> two board if I get it wrong. I'm also concerned that in the "safe" position
> that the continuity indicator on each board would still indicate everything
> green, which could lead to a launch with the pyro's inhibited.
>
> Has anyone flown this configuration before? If so, any suggestions on how
> to hook it up?
>
> Thanks guys.
>
> -Rob
>
Hello,
I'm trying to work out how to wire up the outputs of two Telemetrums (one
primary, one backup) so that I can add an extra arm/disarm rotary switch
between the outputs and the terminal blocks (the NAR L3 requirement to cut
power completely from the pyro's).
This is my initial wiring diagram:
https://github.com/robderstadt/NAR-L3-Project/blob/master/images/plans/Gizm…
Normally I'd just *try* it and see what happens, but I don't want to fry
two board if I get it wrong. I'm also concerned that in the "safe" position
that the continuity indicator on each board would still indicate everything
green, which could lead to a launch with the pyro's inhibited.
Has anyone flown this configuration before? If so, any suggestions on how
to hook it up?
Thanks guys.
-Rob
