Yes, the effect on glowplugs was often interesting!
In those days you had a choice between v. expensive 1.5v dry batteries and 2v wet accumulators. Cox used 1.5v plugs, so would often burn out if a 2v source was used without 'dropper cables'.... Many hours spent poking pins into Cox plugs trying to coax them back to life!
Record Super Nitrex fuel with 30% nitro (if you could find it) gave a little more performance to the Babe Bee - and considerably more to the Tee Dee .049. The PT-19 had rather pointless variable downthrust adjusted by moving the engine against the elastic bands which held it in. I tried retrofitting my Tee Dee to the PT-19 with a radial tank mount; the firewall I made wasn't up to the job and the whole thing came apart in flight!
That lesson taught me a lot.....
A very good point! I reckon we all learned a lot of useful skills during our aeromodelling days!