Here is the data from a 1U cubesat (Fox-1e) so you can see the approximate current and voltage (the Voltage is Bat1+Bat2+Bat3 which is the same bus that the panels feed through the MPPT.  We just found out that these solar cells are no longer available; the newer ones are more efficient (was it 8%?) so the numbers will be a bit better.

73,

Burns Fisher, WB1FJ
AMSAT(R) Engineering -- Flight Software


On Fri, Oct 28, 2022 at 11:22 PM Eric Skoog <eric.n.skoog@gmail.com> wrote:
Good idea, and since AMSAT's finances were reported at the Space Symposium to be in such great shape....................perhaps that's possible.
Or alternatively, GOLF eng team member Leandra's parents live there and she visits them regularly...............not to mention that FOX+ volunteer, Matthew Leonard LIVES there!! 😱

eric


On Fri, Oct 28, 2022 at 10:05 PM Bob Stricklin <bstrick@n5brg.com> wrote:
Good comments Eric.

I was really looking for info on the power available myself. I know how to work through it but thought I would just do a google search and this popped up.
I have not followed the Golf developments closely so Burns comment about size and deploying cells was enlightening to me.

I feel the best source of power info is probably telemetry from previous satellites all things in the solar design and orbit being roughly equal.  There would be an opportunity to increase power by using III V based solar cells but this would be a cost increase and more difficult. I think we are the tail here and not the dog so we have to work with what comes to us on the two wires.

Hopefully your careful reading of the link will help others and become a side benefit of this team working and generating information. There may also be a need for someone to go to Hawaii and talk to these guys.:)

Bob N5BRG


On Oct 28, 2022, at 8:14 PM, Eric Skoog <eric.n.skoog@gmail.com> wrote:

Bob - in addition to the Chapter 5 Pwr Generation material, this is an extremely good reference document for many CubeSat Development areas.  Its open source, publicly published information provides excellent tutorial introductory material for many/most of our AMSAT CubeSat development areas. Consequently, I uploaded a copy to our GOLF SVN under "tech ref docs."  I found the first few chapters very familiar given my 40 year System Engineering experience, and a great refresher for my aging brain!  But I found the remaining chapters contain excellent tutorial information for the major engineering disciplines we must understand and apply to be successful in our ongoing/future CubeSat development efforts. ALL chapters include myriad hyperlinks to more material electronically published in the open literature. The material does "thin out" in the last few chapters as they appear to be 'works in progress.'

What particularly caught my attention was mention of the University of Hawaii's Artemis CubeSat Kit they are offering new satellite developers.  I had no luck finding any further information about that kit on their website, but there is an invite to contact the PoC, Dr. F. Zhu (shu@ hawaii.edu) for more information.  Specifically mentioned is the availability of a 1U CubeSat structure, fully qualified to NASA and CalPoly requirements, whose mechanical pieces add up to $356.02 (not counting solar panels).  That might be worth looking into as Tom Wu is researching commercially available 1U structures for FOX+(PacSat).  Furthermore, it is stated that they also have a CAD package for that 1U structure, viz., a 3D model (in Autodesk Inventor) that is available.  Perhaps that might be of interest to Tom K. and Marwan.  Lastly, I would think Vincent might benefit from one of the references which documents the failures of many past deployable solar panel designs..................good stuff all.

thanks, 
eric (K1TVV)

On Fri, Oct 28, 2022 at 11:19 AM Bob Stricklin via pacsat <pacsat@amsat.org> wrote:



---------- Forwarded message ----------
From: Bob Stricklin <bstrick@n5brg.com>
To: "pacsat@amsat.org" <pacsat@amsat.org>
Cc: 
Bcc: 
Date: Fri, 28 Oct 2022 15:19:09 +0000
Subject: [pacsat] Power Thoughts
Group,

Power requirments is something we need to be looking at carefully.

I found this on the web:

https://pressbooks-dev.oer.hawaii.edu/epet302/chapter/5-5-power-generation/

We can look at some data from other cubsats for power generation. Reviewing Falconsat-3 telemetry would be a good idea.

Power and thermal design will play off each other.

With a 2.5 W power budget for a cubsat the pacsat payload could be a large power consumer. May effect ability to get onboard.

If Golf T had two of the TMS520 one must have been powered down until needed?

Designing for minimum power will yield more operating time and a longer mission life. Falconsat-3 is demonstrating this point now.

Bob N5BRG


---------- Forwarded message ----------
From: Bob Stricklin via pacsat <pacsat@amsat.org>
To: "pacsat@amsat.org" <pacsat@amsat.org>
Cc: 
Bcc: 
Date: Fri, 28 Oct 2022 15:19:09 +0000
Subject: [pacsat] Power Thoughts
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