Monthly Archives: January 2014

Electrical System

I decided on an all DC system at 96V (Battery Direct Bus) to 112V (Primary Bus).

Pumps for fuel/oxidizer, coolant, hydraulics, etc. are ECM/BLDC motors because they run cooler, produce high amounts of torque at lower speeds, etc.

1-12-2014 12-34-41 PM

Battery Direct Bus powers Cockpit Essential Bus and Battery Bus towards aft for fuel boost pumps for reactor start.

Primary Bus powers Cockpit Primary bus (which in turn can power the Cockpit Essential Bus) as well as buses yet to be defined for hydraulics, coolant, sensors, etc.

Charger powered by Primary Bus charges a battery which supplies the Battery Direct Bus through the Battery Master Switch.

Reactor is a fuel cell powered by fuel/oxidizer.  For simplicity of the system a hypergolic mixture is ideal so we don’t have to worry about ignitors.

1-6-2014 10-41-47 PM

Engines are straight turbojet in VTOL, then afterburners for ascent.  The fan shuts down as the density of the atmosphere decreases.  Afterburners become pure rockets.  Engines are 100% powered by fuel/oxidizer since there is no oxygen in the atmosphere for this military arena.

Coldest Night Yet

It got down to -7.5°F overnight and I was awoken twice by the simulator at 11:40 PM and 4:40 AM because it was having trouble maintaining temperature. With wind chill down to -30°F I elected not to mess with the HVAC until this morning.  It is really frustrating how poorly I planned for the HVAC strategy – something to definitely learn from.

The simulator is heated using an external heat pump when the temperature is above 28°F outside. The compressor is disengaged automatically by the computer below 28°F but the fan continues to circulate the air.  The problem is when the outside air is -7.5°F it acts like an efficient air conditioner – the coils absorb the heat from the air.

Instead I need to shut off the power to the external unit below 28°F and install an internal fan to circulate the air when running the convection heater.

1-6-2014 12-04-59 PM                81YqnXfSaRL._SL1500_[1]

I ran out there this morning to turn off the external unit and I am seeing a temperature rise but due to a couple technical glitches I have no historical temperature data since just before the new year.