Hi Rob C, They are all in Delta pusher jets, x41 Delta Storm, Deltawatt, Eurofighter, Vantis(modified). Airflow should be o.k.
I think i was to blame in the way i burnt out 2 of them, in that i kept it at full throttle for too long and wasn't allowing any cooling off periods. When i went out a couple of nights ago, i was keeping bursts to afew seconds and once the momentum was there, the 6x4 was doing its job for what i want.
I'm off now to test a Keda 2826/07, 2800kv. With a 5x5 APC prop and Hyperion 1600, 3s 25c it was showing 312w and 29A on my wattmeter. ....I'm going to keep checking it for coolness and take it easy to start with.