Originally Posted by asmithnc
Jeremy.... QUIT!! You have a very successful great handling boat on your hands. No water rudder or gyro wing needed.. Not to be mean but your boat is just too slow for the aero forces to work correctly. If the speed was double from what I've seen then yes. There is just not enough air flow. We add water rudder to a flatty for control and to add drag. The drag allows us to correctly trim out the boat whilst in motion. Yours is running perfect and no need to over engineer anything. The only thing I would suggest is adding a three blade prop to the rear engine. The first engine is blowing disturbed air and you need extra surface area on the rear to prop to somewhat counter this. A++ on your build...You should be proud!
I'm guessing that you've missed a bit. This is a rough hull to act as a stable platform to test engine setups, it's speed, handling, and indeed it's looks are almost immaterial. The aim is to sort problems, or unknowns, before finalising the design of a much faster craft. This is a process to iron out any problems on an unusual, but fun, way of running twins. But I'm happy to recap.
To date the following has come to light:
Contrary to what was considered as a lesser way to mount two engines this is in fact developing more power than anticipated.
Problems with keeping fuel mass centrally and at low height are close to being solved.
I'm learning a lot about rudder design.
Twin engine controls are shaping up.
Methods to stabilise the operation of the final boat are under way.
So, to me, this is what modelling is all about. Once I've finished the hybrid hyrdo/flatty the actual boat is I'll run it a few times and move on to the next project. I'm a builder more than a user, it's what I get from this hobby. This test hull is going to have a petrol motor fitted later for another development idea, hence its size, call it future proofing. I don't give a hoot about how this one handles, it has nothing to do with the final design, come the end it's probably going to be made into a highly controllable low speed rescue boat to bring in the various hotty boats that reside on our local spot, or the bin.
The focus of everything I am doing here remains on this, where aerodynamics will matter:
I have considred three blade props, but there simply are not available in the UK, so I achieved that same effect by over pitching the rear prop.