After thinking about it, your spot on. I use the 50mm on elevator for take off because i have fitted a half litre tank in the space behind the canopy and in front of the turbine hatch that empty`s first, so it allows me to start up, taxi out and get a couple of circuit`s before it starts using the main tanks. I switch to a lower rate after take off which is probably around the 35mm mark.

I also have the CofG at 155mm.

cheers
john