[eagle] Mocule Connectors

rjansson@cfl.rr.com rjansson at cfl.rr.com
Sat Jun 30 06:33:10 PDT 2007


John & Juan:

Your EMI problems certainly do present considerable difficulties. Your 
suggestions of placing connectors on multiple faces of a module run 
counter to the whole module mounting plan for Eagle. The modules are 
mounted with only about 1.5mm clearance at the flanges and only about 
16mm clearance on the sides. The "rear end" of the module is also 
difficult as there is just not that much space for cabling and 
connector access. Mechanical designers in the past have been raked over 
the coals for not providing sufficient connector access. The curren 
plan allows about 100mm (I don't have the drawings with me at the 
moment) of space between facing columns of modules for the cabling and 
connector access. This is a plan that is pretty basic to the whole 
wiring plan for Eagle, and it is a result of a lot of experience with 
P3D.

While the basic module design for Eagle, unlike P3D, does not provide 
for the stacking of modules, a small CAN module placed on top of the 
URx, could be considered. Wiring to this sub-module would be by means 
of jumper leads from its connector face into the URx. 

I caution that there currently is not planned for much space above the 
rows of modules as the current spaceframe plan has the modules placed 
fairly closely under the solar panels. This concept is part of the need 
to keep the mass moment of inertia, Izz, high. This is NOT just a 
desirable feature, but a necessary, MUST need for the spin stability of 
the spacecraft. So any top-mounted sub-module would have to not be very 
thick.

All of these issues arise from the practical considerations of the 
overall mission of the spacecraft. Unfortunately for the EMI and 
other "local" issues, we cannot design the spaceframe only for EMI, but 
must solve other mission requirements, too.

I am not trying to be unmovable on the design if the URx, but I am 
trying to explain how we can have a successful mission.

'73,
Dick, KD1K


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