"Jim Logajan" wrote in message
.. .
"pTooner" wrote:
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.

Theory of biplanes might provide the theoretical basis. My copy of
"Theoretical Aerodynamics" by L. M. Milne-Thomson discusses wing
interference between the wings of biplanes in chapter 8. (It's a Dover
publication, so it is still in print and inexpensive.)

Also, try a Google search on this set of search words (with or without
the search word "stagger"):
aerodynamic gap biplanes

I'm fairly confident that interference
between the front wings (or rear) can be minimized by reasonable
spacing and differing dihedral.

Staggering the wings tends to help reduce interference also.

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.

I suspect having one set high that the other would equivalent to a large
staggering angle.

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.

If you are not already familiar with it, you should browse this site,
which include planes that attempt to satisfy some of your requirements
(the Wernicke Aircar uses low aspect ratio wings to try to meet some of
your requirements):
http://www.roadabletimes.com/

I am getting lots of good info from the sources you recommend and I'll try
the book store tomorrow for that book. If they don't have it I'll go to
Amazon. My basic concept/question is like this. Assuming optimum airfoil
in each case which may well be different; I could build a 20ft span 4 ft
chord wing for 80sqft or two 20span 2 ft chord or 4 10ft span 2 foot chord
and they all equal the same area. What would be their relative lift and
drag numbers? (probably pretty close) BUT would they have strange
characteristics at odd angles of attack? (That is a semi-rhetorical
question)

Gerry