Originally Posted by m_ark
twin will surely give you better static thrust low down, but how much prop pitch do you need to get to 275km?
how much static thrust will that kind of prop pitch give on launch?
Many don't believe you can compare water craft to air .. but in fact fluid dynamics is just that ... the density of the fluid just alters equations.
Watch serious power boats and you see twin set-ups. As boater - I know that a single 250hp motor cannot beat a twin 250hp setup, ie 2 x 125 hp.
There is logic in my madness ... the twin set-up with contra props will remove the demon torque problems of high power.
The pitch speed before losses of a 5x5 prop at the revs I'm looking at is well over 350kph. After losses and as it's a twin giving that extra ... I reckon she can hit it. Even if she doesn't - it will be fun trying.
I'm just surprised that I seem to be only one going for it !