[NicholasDavid]

Thought of building a 4s 6" beast. But I want to be able to run the occasional 5s pack, you know, for fun.

    I already have most of the parts. 30-40A escs are usually good for 2-6s battery's. Lower KV motors in the 1800-2100kv range. But for instance immersion RC fatshark vtx is only good to 17v max.

 So my question is.... Is a 12v 500mah pololu step down regulator into the v3 fatshark VTX the way to do it. Or a 12v step up regulator off the esc's bec 5v/3a output.

My trouble is 5s is to much for Voltage in on the 600mw vtx I already have (18.5 5s on a 17v max.) and the nice escs I already have, the 5v bec is to little to power the VTX.   Let me know what you think.

6" props on 5s should be enough for 100 mph on a no wind day. Maybe a tail breeze.

I'm talking about a 250-280  Carbon racer mind you

[mazevx]

Hello, the Pololu step down is the way you should go, they normaly accept up to 36V input, but you should make sure that your vtx isnt pulling to much current, if there there is a way to measure the current pull of your vtx Do this before buying a bec. There are several other 12v bec with 1A or more wich are small and not to heavy. Be aware that you may need some kind of filtering device because to have a good Image without interferences.