Re: [Crrcsim-devel] Propellers and rotors

[Jens W. W. <je...@gm...>]

Hello Andreas,

sorry for answering that late: there's not much spare time to do so.

Although I'm not really active on CRRCSim anymore, I suggest to discuss
development-related questions on crrcsim-devel and let the yahoo group be a
"user's group".

General statement: the current "automagic" code is made for people who want
to have a power system (for a given FIXED WING plane) that is reasonably
realistic without any setup trouble. So it is simple -- one
battery/engine/propeller. It is not meant to create a configuration for
several motors/engines and so on.

However, the world is not static at all ;-)

Your current way looks right from a glance. Using a rotor instead of a
propeller (which has a different physical model) and looking at the parts of
an automagic configuration. 
It is also correct to sum up the power which is delivered to the
propellers/rotors connected to one engine. This engine has to power all of
them, and in turn needs more current (which has to be delivered by the battery).

You asked about whether every prop/rotor should get one engine:
yes, that's needed in my opinion. The engine is defined by
  1. from xml input: best efficiency, efficiency at setpoint and a
     certain rotational speed
  2. power needed by propellers to deliver the requested thrust

The propellers in turn are defined by geometry and need a certain rotational
speed to deliver the requested combination of thrust and airspeed. If you
connect different rotors/propellers to one engine, they will most certainly
need different rotational speeds.

One good thing about the current code is: if you make a mistake in the
automagic configuration, the simulation code will show it to you by not
providing requested thrusts and things like that.

And automagic configuration code might not be easy if you don't understand
the physics -- in the end one should not touch it at all in that case.

Best regards,
Jens