questions on multi-wing planforms

I don't want to be too negative but could I suggest that if you are
struggling with these relatively fundamental issues that such a project
might be a little beyond you. These are not issues for someone without
aerodynamic knowledge and what you describe is certainly not a design that
is likely to be successful for a first time amateur designer.

However let me give you a little insight into how to tackle the problem.

Yes you could develop your own theory based on biplane type theory (i.e. a
bound vortex respresenting each wing) and use this to predict the flow
field. Any number of aerodynamics texts will give you the basic theory but
you will need to extend that for your application.

However I wouldn't bother with this with the computational tools available.

Just get a Vortex lattice code such as the NASA VLM code or Drela's AVL (or
better still a panel code such as PMARC or Peter Garrisons CMARC) and use
this. Such an approach is far more accurate and someone who knows what they
were doing would have a good feel for the issues and probably fix most of
the major problems in less than a days work.

However please be careful there are a lot of traps for new players even with
these sorts of tools. Don't treat programs like this as a balck box .. try
to understand what is going on inside them and what the limitations are.

Once you have done your computer analysis build a large scale model and go
and fly it before you waste time building the full size airplane.




"pTooner" wrote in message
...
Firstly, I am new here although I've been reading for a few days. For
anyone with more knowledge than I, I keep considering building a small 4
wing aircraft. Not stacked, but two up front and two in the rear. I have
read frequently of problems supposedly resulting from interference of the
airflow between wings, but I can't seem to find anything very specific.
I'm
fairly confident that interference between the front wings (or rear) can
be
minimized by reasonable spacing and differing dihedral. I'm not sure what
the effect of the airflow coming off the front wings will have on the rear
set. I don't know whether I could remove most of the problem by having
one
set considerably higher (how much?) than the other set or if it is
reasonable to have them on more or less the same height. The reason for
the concept is trying to get a wingspan small enough to fit into a normal
garage and conceivably take off and land from streets and highways. I
visualise something in a two place plane that would fall into something of
the appeal category of a motorcycle or small sports car. Any thoughts
would
be appreciated.

Gerry