battery help

yes thats the one eric thanks , so i need a 4s 3000 battery and a smaller prop say 9x6 the rest went straight over my head:silly:

Having re read my post my apologies. Clear as mud!

What I was trying to say was that you have to balance obtaining static thrust with a finer pitch for take off against a suitable pitch for the required flight speed. The faster the plane flies the worse that compromise becomes for static thrust.

When taken to extreme, as in the 1930's Schneider Trophy float planes, the fixed pitch props set for the 400+ mph top speed so compromised the static thrust that take off was pretty marginal despite having massive horse power installed in a lightweight plane.

Spits and Hurris had to be fitted with variable pitch props as their power was increased.Take- off was accomplished with fine pitch or they ran out of runway trying to reach flying speed. Ooops!! Sometimes sprog pilots forgot to their dismay.

To be fair part of the problem of lack of thrust on take off with coarse fixed pitch props was it slows the engines down so much they no longer produced maximum power let alone any inefficiencies of the prop. On the plus side slowing an IC motor down in this way (within reason) does not damage it.

On the other hand under the same conditions electric only suffers from the coarse pitch prop inefficiency as the motor will simply do its best to achieve normal full power revs regardless of load but will overload everything whilst doing it, hence the use of a Watt meter.