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

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. 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
>
>

Go from 4 to 1.
The Dyke Delta JD-2 will fold up to fit in a one car garage. And it is
designed to be towed behind a car on it's own wheels; though, some have
had issues with getting trailer tags to do it legally.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

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. 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
Look up "Monk Factor"!

"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/

"Ernest Christley" > 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. 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
>
> Go from 4 to 1.
> The Dyke Delta JD-2 will fold up to fit in a one car garage. And it is
> designed to be towed behind a car on it's own wheels; though, some have
> had issues with getting trailer tags to do it legally.

I'm familiar with the plane, and it is reputed to be very difficult and
lengthy to build.

Gerry

"ELIPPSE" > wrote in message
oups.com...
>
> 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.
>> 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
> Look up "Monk Factor"!
>
In quotes that term doesn't bring any reponse in google. Without quotes it
brings an unmanageable amount but doesn't appear to have anything to do with
aerodynamics. Can you elaborate a bit?
Gerry

All very helpful and interesting stuff. Thanks a lot.
Gerry
"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/

"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

"pTooner" > wrote in message
.. .
>
> "Ernest Christley" > wrote in message
> ...

<<snip>>>

>
> I'm familiar with the plane, and it is reputed to be very difficult and
> lengthy to build.
>
> Gerry

Not compared to designing, building, and testing a unique design with an odd
planform...

KB

"Kyle Boatright" > wrote in message
...
>
> "pTooner" > wrote in message
> .. .
>>
>> "Ernest Christley" > wrote in message
>> ...
>
> <<snip>>>
>
>>
>> I'm familiar with the plane, and it is reputed to be very difficult and
>> lengthy to build.
>>
>> Gerry
>
> Not compared to designing, building, and testing a unique design with an
> odd planform...
>
> KB

Welllll, I guess I can't argue with that. <G>
Gerry
>
>

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
>
>

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. 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

John Roncz called a 3 surface airplane he participated in the design of
"the aerodynamicists full employment act"!

You will, with optimization of all the variables. be lucky to get 40%
of the lift/drag ratio of an equivalent conventional planform.

But the bigger problem will be control. Pitch stability, in and out of
ground effect, will be a formidable problem, as will stall
characteristics. Compromises needed to make the handling acceptable
may make the efficiency even worse.

I agree with Ernst - a low aspect ratio delta/lifting body makes more
sense. Perhaps a 2 seat Facetmobile with the outer portions folding
inward like a Dyke Delta.

But have you looked at all the wires around most roads? Not an area I
would want to use for landing and takeoff.

"flybynightkarmarepair" > wrote in message
oups.com...
>
> 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.
>> 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
>
> John Roncz called a 3 surface airplane he participated in the design of
> "the aerodynamicists full employment act"!
>
> You will, with optimization of all the variables. be lucky to get 40%
> of the lift/drag ratio of an equivalent conventional planform.

Can you elaborate? I don't see why this should be true.
>
> But the bigger problem will be control. Pitch stability, in and out of
> ground effect, will be a formidable problem, as will stall
> characteristics. Compromises needed to make the handling acceptable
> may make the efficiency even worse.

Well, most tandem wing aircraft are designed to make normal stall
impossible. (the rutan designs for instance) Pitch stability is a problem
that I thought had been pretty well handled by airfoil design in canard
aircraft years ago. My thoughts (I wouldn't call it a design) are simply
two sets of biplane wings mounted fore and aft. Biplane wings don't
normally present much of an efficiency problem except for the bracing which
isn't stricly necessary (The hyperbipe was a pretty efficent design) I
certainly agree that handling especially in the pitch axis is the major
challenge, but I don't see why it should present a much bigger problem than
the flying flea family of aircraft where it was eventually solved
satisfactorily.
>
> I agree with Ernst - a low aspect ratio delta/lifting body makes more
> sense. Perhaps a 2 seat Facetmobile with the outer portions folding
> inward like a Dyke Delta.

Perhaps, but it's been tried many times and with very limited success. I
know of NO attempt to build the 4 wing system that I envision. That seems
strange when you consider that about every imaginable combination has been
tried at one time or another. Didn't someone finally build an operable
ornithopter?

>
> But have you looked at all the wires around most roads? Not an area I
> would want to use for landing and takeoff.

Good point, but they aren't everywhere. ;-)

Gerry
>

You might look up all the varieties of "Flying Fleas" and the Q-200 kits for
small, multiwing aircraft.
"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
>

pTooner wrote:
> ...
>
> Well, most tandem wing aircraft are designed to make normal stall
> impossible. (the rutan designs for instance) Pitch stability is a problem
> that I thought had been pretty well handled by airfoil design in canard
> aircraft years ago. My thoughts (I wouldn't call it a design) are simply
> two sets of biplane wings mounted fore and aft. Biplane wings don't
> normally present much of an efficiency problem except for the bracing which
> isn't stricly necessary (The hyperbipe was a pretty efficent design) I
> certainly agree that handling especially in the pitch axis is the major
> challenge, but I don't see why it should present a much bigger problem than
> the flying flea family of aircraft where it was eventually solved
> satisfactorily.

This sounds like sort of a biplane version of the dragonfly.

> ...
> Perhaps, but it's been tried many times and with very limited success. I
> know of NO attempt to build the 4 wing system that I envision. That seems
> strange when you consider that about every imaginable combination has been
> tried at one time or another.

Everytime I've had an idea for some way to build an airplane that I
had never seen before it took only a few minutes on the web to find
examples of the concpet that had already been built and flown.

So I daresay if you have a novel idea that has never been flown
there is probably a very good reason why it hasn't.

If you are merely interested in being able to get the plane
easiliy into a garage, there are many folding wing designs
to choose from or adapt. In addition to the Flying Flea,
the kitfox is another.

Regardless, good luck.

> Didn't someone finally build an operable
> ornithopter?
>

There have been many small (e.g. bird-sized) ones flown. You
can buy a plastic toy ornithopter for under $50.00 and there are
plans available on the web to build a rubber-bad powered version.

> >
> > But have you looked at all the wires around most roads? Not an area I
> > would want to use for landing and takeoff.
>
> Good point, but they aren't everywhere. ;-)
>

You have legal restrictions to be concerned with on public roads,
but there are private roads.

"Robert Little" > wrote in message
...
> You might look up all the varieties of "Flying Fleas" and the Q-200 kits
> for small, multiwing aircraft.

I have done so, thanks.
Gerry
> "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
>>
>
>

Even if everything works just the way you dream it will how will you
see where you're going?

>"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
>>
>
>

"Drew Dalgleish" > wrote in message
...
> Even if everything works just the way you dream it will how will you
> see where you're going?

You are assuming a far more complete design than actually exists, but I
don't see why that should be a problem.

Gerry
>
>>"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
>>>
>>
>>
>

pTooner wrote:
> "ELIPPSE" > wrote in message
> oups.com...
> >
> > 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.
> >> 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
> > Look up "Monk Factor"!
> >
> In quotes that term doesn't bring any reponse in google. Without quotes it
> brings an unmanageable amount but doesn't appear to have anything to do with
> aerodynamics. Can you elaborate a bit?
> Gerry
Hi, Gerry! Munk factor has to do with the effect multiple wing
placement has on the induced drag of tandem wings and biplane wings.
Darrol Stinton in his book "The Design Of The Aeroplane" has an
excellent, easy to understand section on it, with lots of graphs!

"pTooner" > wrote:
> 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)

Since a higher aspect ratio wing generally has a better lift/drag ratio,
increasing the effective wingspan would normally be a good thing - assuming
all other variables remain constant. But clearly wing gap interference
inserts an additional variable.

Another thing you might want to look into is the "multiplane" (I couldn't
remember the proper name for the concept in my first reply, otherwise I'd
have mentioned it earlier). The concept dates as far back as 1893! Horatio
Phillips designed (and did some short test flights) of what can only be
described as "Venetian blinds" wings. Here are some web sites, with some
background info and photos (some of the photos can be clicked on to get
larger images):

http://www.centennialofflight.gov/essay/Evolution_of_Technology/phillips/Tech4.htm
http://www.ctie.monash.edu.au/hargrave/phillips.html

Another nice photo of Phillips multiplane:
http://invention.psychology.msstate.edu/inventors/i/Phillips/photos/Phillips_first_multiplane.jpeg

Lastly, you should consider getting a copy of "Simplified Aircraft Design
for Homebuilders" by Dan Raymer. (He has his own website:
http://www.aircraftdesign.com/)

"pTooner" > wrote in message
...
>
> "Drew Dalgleish" > wrote in message
> ...
> > Even if everything works just the way you dream it will how will you
> > see where you're going?
>
> You are assuming a far more complete design than actually exists, but I
> don't see why that should be a problem.
>
> Gerry
I am fairly certain that tandem biplane designs existed in the early
days--in addition to the obvious case of the Wright Flyer.

However, I will second the suggestion to stay with one of the various
folding wing designs. Also, unless you are *very* masochistic, you probably
won't fly very ofter if you also have to tow the aircraft to and from the
airport, so the ability to be towed at highway speeds (or even street
speeds) may not be as usefull as the ease of folding and unfolding the
wings. I would suggest asking around your local airport(s) regarding the
storage cost for a folding wing aircraft--you may be able to share part of a
hangar or even get a reasonable deal from a maintenance facility if they
have permission to move the plane out of the way when they need the
workspace. Also, the way Tee-hangars are constructed at some airports,
there may be a half hangar on the end of each row--and a folding wing
airplane would only need about half of a half hangar!

BTW, depending on the size of the Tee hangars on the row, you might be able
to nose a VariEze or even a LongEze into a half hangar and still share the
back part of the hangar for storage or office space--depending on the rules
at your airport.

Also the Nesmith Cougar has a folding wing, and if you are of very small
stature there is the Stits Playmate.

I hope this helps
Peter
> >
> >>"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
> >>>
> >>
> >>
> >
>
>

"Peter Dohm" > wrote in message
. ..
> "pTooner" > wrote in message
> ...
>>
>> "Drew Dalgleish" > wrote in message
>> ...
>> > Even if everything works just the way you dream it will how will you
>> > see where you're going?
>>
>> You are assuming a far more complete design than actually exists, but I
>> don't see why that should be a problem.
>>
>> Gerry
> I am fairly certain that tandem biplane designs existed in the early
> days--in addition to the obvious case of the Wright Flyer.

Well, I tend to think that it's only a tandem wing if both portions
contribute substantially to the list. I don't know of any of those,
although I'd like to find them for informational purposes.

>
> However, I will second the suggestion to stay with one of the various
> folding wing designs. Also, unless you are *very* masochistic, you
> probably
> won't fly very ofter if you also have to tow the aircraft to and from the
> airport, so the ability to be towed at highway speeds (or even street
> speeds) may not be as usefull as the ease of folding and unfolding the
> wings. I would suggest asking around your local airport(s) regarding the
> storage cost for a folding wing aircraft--you may be able to share part of
> a
> hangar or even get a reasonable deal from a maintenance facility if they
> have permission to move the plane out of the way when they need the
> workspace. Also, the way Tee-hangars are constructed at some airports,
> there may be a half hangar on the end of each row--and a folding wing
> airplane would only need about half of a half hangar!

Those are good ideas, but I never consider towing. Picture instead, someone
who happened to own a few acres on the dead end of a very rural florida road
that is straight as an arrow. ;-)

Gerry

Awright.

There's more to aerodynamics than that covered by your philosophy.

Area and airfoil are not really the right starting place for a new
and novel configuration.


Re: the dimensions of your wings...

First - learn about Reynolds number.
Very few of the published airfoils work well below about 3 meg RN.

What does that mean in regard to your choices?

Well, the two-foot chord wing is going to have to move pretty fast to make
3 meg RN.

The four-foot chord wing will have twice the RN from the start.


Richard

> >
> > You will, with optimization of all the variables. be lucky to get 40%
> > of the lift/drag ratio of an equivalent conventional planform.
>
> Can you elaborate? I don't see why this should be true.

Well, let's see. The back wing(s) operate in the downwash of the
forward wings, there's a hit there. The upper wings operate in a flow
field affected by the lower wings, there's a hit there. Twice as many
wingtip vortices, take a hit there, and at some angles of attack, the
aft wing(s) will be operating in the vortice of the front wing(s).

> >
> > But the bigger problem will be control. Pitch stability, in and out of
> > ground effect, will be a formidable problem, as will stall
> > characteristics. Compromises needed to make the handling acceptable
> > may make the efficiency even worse.
>
> Well, most tandem wing aircraft are designed to make normal stall
> impossible. (the rutan designs for instance)

There is a price paid in efficiency, and in landing speed in making
this NECESSARY trait possible. It's necessary because a canard or
tandem wing design is very vulnerable to an un-recoverable deep stall.
The consequence is that you cannot optimize the angle of attack for
both wings simultaneously, and that the C ell Max of the combined
system is degraded, making the landing speed higher, or the wings
bigger (which will hurt efficiency AGAIN).

Pitch stability is a problem
> that I thought had been pretty well handled by airfoil design in canard
> aircraft years ago. My thoughts (I wouldn't call it a design) are simply
> two sets of biplane wings mounted fore and aft. Biplane wings don't
> normally present much of an efficiency problem except for the bracing which
> isn't stricly necessary (The hyperbipe was a pretty efficent design)

Pretty efficient for a biplane, but nowhere near as efficient as a
conventional design.

> I certainly agree that handling especially in the pitch axis is the major
> challenge, but I don't see why it should present a much bigger problem than
> the flying flea family of aircraft where it was eventually solved
> satisfactorily.

Again, by limitations that hurt efficiency. And a good half-dozen
people died before the pitch stability issue was solved. That was
actually a problem at cruise/top speed.

The transition between operating in ground effect and out of it is
pretty tricky for a equal area tandem wing airplane. This was seen in
some of the first experimental Wing In Ground effect surface skimmers.
They had tremendous pitch stability (a problem if you're trying to
rotate) until they suddenly didn't, and they would pitch up quite
violently. That's one reason the Quickies have ANHEDRAL on the forward
wing, and Dihedral on the aft wing, as well as mounting the forward
wing lower than the aft wing. In this way, with a pitch up to rotate,
both wings come out of ground effect at much closer to the same
instant, without a sharp pitch divergence.

> > I agree with Ernst - a low aspect ratio delta/lifting body makes more
> > sense. Perhaps a 2 seat Facetmobile with the outer portions folding
> > inward like a Dyke Delta.
>
> Perhaps, but it's been tried many times and with very limited success.

Various low aspect ratio designs have been flow since the twenties,
it's true. The Burnellis, the Spratt, the Fike designs. The Dyke Delta
is a low aspect double delta, with the main cabin airfoil shaped. But
true lifting bodies were basically unknown until the 1960's. John
McPhee wrote about one of them in "The Deltoid Pumpkin Seed". The the
Facetmobile is, IMHO, the most successful general aviaition true
lifting body design.

"cavelamb" > wrote in message
k.net...
> Awright.
>
> There's more to aerodynamics than that covered by your philosophy.

Huh???

>
> Area and airfoil are not really the right starting place for a new
> and novel configuration.

Then where WOULD be the right starting place?

>
>
> Re: the dimensions of your wings...
>
> First - learn about Reynolds number.
Okay

> Very few of the published airfoils work well below about 3 meg RN.
>
> What does that mean in regard to your choices?
>
> Well, the two-foot chord wing is going to have to move pretty fast to make
> 3 meg RN.

How fast? None of these were really choices, just random numbers for
explanation. In other words, 4 10x1 wings = 40 sq ft. or 1 20x2 wing = 40
sq ft. The most important single factor in wing design appears to be square
feet. ??
>
> The four-foot chord wing will have twice the RN from the start.
That's built into the RN equation. What's the relevance??

I have no argument here, I'm looking for info. So far, I've gotten some
pretty good references.

Gerry

"flybynightkarmarepair" > wrote in message
oups.com...
>
>> >
>> > You will, with optimization of all the variables. be lucky to get 40%
>> > of the lift/drag ratio of an equivalent conventional planform.
>>
>> Can you elaborate? I don't see why this should be true.
>
> Well, let's see. The back wing(s) operate in the downwash of the
> forward wings, there's a hit there.

That's not necessarily true, it depends on many additional factors. The
same could be said for the main sail on a sloop operating in the downwash of
the jib, but it works damned well.

The upper wings operate in a flow
> field affected by the lower wings, there's a hit there.

Seems I read somewhere that as long as the gap is about 1.5 times the chord
that isn''t a factor?

Twice as many
> wingtip vortices, take a hit there,

Maybe - I'm not sure about that one. There are certainly other
considerations.

and at some angles of attack, the
> aft wing(s) will be operating in the vortice of the front wing(s).

That strikes me as the single most important problem with this
consideration.


>
>> >
>> > But the bigger problem will be control. Pitch stability, in and out of
>> > ground effect, will be a formidable problem, as will stall
>> > characteristics.

See above.

Compromises needed to make the handling acceptable
>> > may make the efficiency even worse.

Please elaborate.

>>
>> Well, most tandem wing aircraft are designed to make normal stall
>> impossible. (the rutan designs for instance)
>
> There is a price paid in efficiency, and in landing speed in making
> this NECESSARY trait possible. It's necessary because a canard or
> tandem wing design is very vulnerable to an un-recoverable deep stall.
> The consequence is that you cannot optimize the angle of attack for
> both wings simultaneously, and that the C ell Max of the combined
> system is degraded, making the landing speed higher, or the wings
> bigger (which will hurt efficiency AGAIN).

Generally, I agree. OTOH, all designs are compromises of some kind.

>
> Pitch stability is a problem
>> that I thought had been pretty well handled by airfoil design in canard
>> aircraft years ago. My thoughts (I wouldn't call it a design) are simply
>> two sets of biplane wings mounted fore and aft. Biplane wings don't
>> normally present much of an efficiency problem except for the bracing
>> which
>> isn't stricly necessary (The hyperbipe was a pretty efficent design)
>
> Pretty efficient for a biplane, but nowhere near as efficient as a
> conventional design.

The published specs don't seem to agree with you there.

>
>> I certainly agree that handling especially in the pitch axis is the
>> major
>> challenge, but I don't see why it should present a much bigger problem
>> than
>> the flying flea family of aircraft where it was eventually solved
>> satisfactorily.
>
> Again, by limitations that hurt efficiency. And a good half-dozen
> people died before the pitch stability issue was solved. That was
> actually a problem at cruise/top speed.

Sad, but many people died to learn what we now know about aeronautics.

>
> The transition between operating in ground effect and out of it is
> pretty tricky for a equal area tandem wing airplane. This was seen in
> some of the first experimental Wing In Ground effect surface skimmers.
> They had tremendous pitch stability (a problem if you're trying to
> rotate) until they suddenly didn't, and they would pitch up quite
> violently. That's one reason the Quickies have ANHEDRAL on the forward
> wing, and Dihedral on the aft wing, as well as mounting the forward
> wing lower than the aft wing. In this way, with a pitch up to rotate,
> both wings come out of ground effect at much closer to the same
> instant, without a sharp pitch divergence.

Interesting observation that I haven't come across previously.

>
>> > I agree with Ernst - a low aspect ratio delta/lifting body makes more
>> > sense. Perhaps a 2 seat Facetmobile with the outer portions folding
>> > inward like a Dyke Delta.
>>
>> Perhaps, but it's been tried many times and with very limited success.
>
> Various low aspect ratio designs have been flow since the twenties,
> it's true. The Burnellis, the Spratt, the Fike designs. The Dyke Delta
> is a low aspect double delta, with the main cabin airfoil shaped. But
> true lifting bodies were basically unknown until the 1960's. John
> McPhee wrote about one of them in "The Deltoid Pumpkin Seed". The the
> Facetmobile is, IMHO, the most successful general aviaition true
> lifting body design.

I agree.
\

>

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. 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
Gerry! Look up the Stinton reference I gave you, read it over a bunch
of times 'til you start getting an idea of how spacing and stagger
would affect the wing placement. Then keep in mind, this is
Experimental aviation! Try your idea in a large model; see how that
works. But don't let the nay-sayers keep you from experimenting.
There's no progress in building the same thing over and over. Your
creation doesn't have to be the most efficient thing out there. All
designs call for some compromises! Good experimenting!

"ELIPPSE" > wrote in message
ups.com...
>
> 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.
>> 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
> Gerry! Look up the Stinton reference I gave you, read it over a bunch
> of times 'til you start getting an idea of how spacing and stagger
> would affect the wing placement. Then keep in mind, this is
> Experimental aviation! Try your idea in a large model; see how that
> works. But don't let the nay-sayers keep you from experimenting.
> There's no progress in building the same thing over and over. Your
> creation doesn't have to be the most efficient thing out there. All
> designs call for some compromises! Good experimenting!
>

Thanks, I haven't located that book yet, but I will. And I will on the
experimenting too.
Gerry

pTooner wrote:
> "Ernest Christley" > 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. 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
>>
>>Go from 4 to 1.
>>The Dyke Delta JD-2 will fold up to fit in a one car garage. And it is
>>designed to be towed behind a car on it's own wheels; though, some have
>>had issues with getting trailer tags to do it legally.
>
>
> I'm familiar with the plane, and it is reputed to be very difficult and
> lengthy to build.
>
> Gerry
>
>

Aren't they all? 4 years and running here. Almost ready to close up
the skins.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

flybynightkarmarepair wrote:

> Various low aspect ratio designs have been flow since the twenties,
> it's true. The Burnellis, the Spratt, the Fike designs. The Dyke Delta
> is a low aspect double delta, with the main cabin airfoil shaped. But
> true lifting bodies were basically unknown until the 1960's. John
> McPhee wrote about one of them in "The Deltoid Pumpkin Seed". The the
> Facetmobile is, IMHO, the most successful general aviaition true
> lifting body design.
>

I've heard this stated several times, and always found it a bit strange.

What is it that makes the Facetmobile so successful? A single prototype
that crashed, vs the Dyke Delta that has had dozens flying and about
half a dozen currently airworthy. Why is the Dyke Delta not considered
a lifting body design? The fuselage provides the majority of the lift
at cruise, according to John Dyke and verified in XPlane (if that can be
considered any sort of verification).


--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

>>
>> I'm familiar with the plane, and it is reputed to be very difficult and
>> lengthy to build.
>>
>> Gerry
>>
>>
>
> Aren't they all? 4 years and running here. Almost ready to close up the
> skins.
>
> --

I'd love to see one of these puppies in progress. You wouldn't happen to be
near Florida would you?

Gerry
> This is by far the hardest lesson about freedom. It goes against
> instinct, and morality, to just sit back and watch people make
> mistakes. We want to help them, which means control them and their
> decisions, but in doing so we actually hurt them (and ourselves)."

Build models of your ideas. Try them as free flight first. you may even
be able to do some customizing in the more advanced RC flight sim
programs.
If you can get the small models to fly build them bigger. get up to
about half scale.
if that works then build a full sizer.

pTooner wrote:
>>>I'm familiar with the plane, and it is reputed to be very difficult and
>>>lengthy to build.
>>>
>>>Gerry
>>>
>>>
>>
>>Aren't they all? 4 years and running here. Almost ready to close up the
>>skins.
>>
>>--
>
>
> I'd love to see one of these puppies in progress. You wouldn't happen to be
> near Florida would you?
>

Dave Williams down in Key Largo may not have his rebuild buttoned up
yet. The yahoo group links to a Frapper map that will show you where
several are being built.


--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

Ernest Christley wrote:
> flybynightkarmarepair wrote:
>
> > Various low aspect ratio designs have been flow since the twenties,
> > it's true. The Burnellis, the Spratt, the Fike designs. The Dyke Delta
> > is a low aspect double delta, with the main cabin airfoil shaped. But
> > true lifting bodies were basically unknown until the 1960's. John
> > McPhee wrote about one of them in "The Deltoid Pumpkin Seed". The the
> > Facetmobile is, IMHO, the most successful general aviaition true
> > lifting body design.
> >
>
> I've heard this stated several times, and always found it a bit strange.
>
> What is it that makes the Facetmobile so successful? A single prototype
> that crashed, vs the Dyke Delta that has had dozens flying and about
> half a dozen currently airworthy. Why is the Dyke Delta not considered
> a lifting body design? The fuselage provides the majority of the lift
> at cruise, according to John Dyke and verified in XPlane (if that can be
> considered any sort of verification).

This is an admittedly arbitrary distinction. The cabin on a Dyke Delta
is, again, IMHO, not well integrated into the fuselage/wing - MY
definition of a lifting body is that it's ALL an integrated whole.
Compare these pictures of a Dyke Delta:
http://www.pivot.net/~psi/philt2.htm
and the Facetmobile:
http://members.aol.com/slicklynne/FMX4IF1.JPG
The other piece of my arbitrary distinction is that the Dyke Delta has
discernable wings, while the Facetmobile doesn't.

I think the Dyke Delta is a great airplane; one I've loved since I read
about it in Air Progress probably nearly 40 years ago.

"flybynightkarmarepair" > wrote

> This is an admittedly arbitrary distinction. The cabin on a Dyke Delta
> is, again, IMHO, not well integrated into the fuselage/wing - MY
> definition of a lifting body is that it's ALL an integrated whole.

So, in your opinion, the Hyper Bipe is not a lifting body? It provides
substantial lift, therefore, it is a lifting body, in everyone's view,
except yours.

I submit that you are incorrect.
--
Jim in NC

Gerry and all,

Been following this most interesting conversation on aircraft design.
I would just point out some issues that one is to consider when
endeavouring to devise his own desin.

> Then where WOULD be the right starting place?
>

This is the most important point. It is unwise to start thinking of
SOLUTIONS ( number of wings, biplane, delta, tandem wings...) before
posing the PROBLEM, and establishing what the aircraft will be required
to do.

I understand that this particular airplane should be small, light, and
able to take off from an unprepared stretch of private road. And it
should be storable in a garage.

There are several designs (some of them out of the US) that fulfill
these requirements, without resorting to exotic or complicated technical
solutions. And yet have outstanding handling qualities, payload and
performance on a reasonable power.

The MCR 01 two seater is one of them :
http://www.avnet.co.uk/lts/pages/mcr.htm

>>
>> Re: the dimensions of your wings...
>>
>> First - learn about Reynolds number.
> Okay
>
>> Very few of the published airfoils work well below about 3 meg RN.
>>
>> What does that mean in regard to your choices?
>>
>> Well, the two-foot chord wing is going to have to move pretty fast to make
>> 3 meg RN.

The MCR 01 has a two foot chord wing, and the four seater we built has a
3 foot chord.


Concerning the Delta Dyke, one of my buddy owns one, and it is certainly
not an answer to the original poster's requirements. On the contrary,
it is a dog in flight, and very tricky. Deltas are definitely not a
corrrect solution to any slow airplane.

Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr

"GTH" > wrote in message
...
> Gerry and all,
>
> Been following this most interesting conversation on aircraft design.
> I would just point out some issues that one is to consider when
> endeavouring to devise his own desin.
>
>> Then where WOULD be the right starting place?
>>
>
> This is the most important point. It is unwise to start thinking of
> SOLUTIONS ( number of wings, biplane, delta, tandem wings...) before
> posing the PROBLEM, and establishing what the aircraft will be required to
> do.
>
> I understand that this particular airplane should be small, light, and
> able to take off from an unprepared stretch of private road. And it should
> be storable in a garage.
>
> There are several designs (some of them out of the US) that fulfill these
> requirements, without resorting to exotic or complicated technical
> solutions. And yet have outstanding handling qualities, payload and
> performance on a reasonable power.
>
> The MCR 01 two seater is one of them :
> http://www.avnet.co.uk/lts/pages/mcr.htm
>

Thanks for your response, Gilles. A bit of clarification, perhaps. This is
not really a design to fullfill a mission. It's more of a "why not"
exercise. The very short wingspan is the only real design criteria, and it
is just my idea rather than a definite need anyone has. The MCR 01 is a
very interesting design, but with a wingspan of over 20 feet it doesn't fit
my plan. Consider that if you made it a 10 foot span biplane it would
perhaps fit the bill?? I could restate it this way, if you divided the 20
foot wingspan of the MCR 01 into two wings either tandem or stacked would it
provide similar performance? How about 4 10 foot wings with one foot chord?
I don't really know the answer, I'm just brainstorming to see if anyone else
knows the answer.

Gerry


>>>
>>> Re: the dimensions of your wings...
>>>
>>> First - learn about Reynolds number.
>> Okay
>>
>>> Very few of the published airfoils work well below about 3 meg RN.
>>>
>>> What does that mean in regard to your choices?
>>>
>>> Well, the two-foot chord wing is going to have to move pretty fast to
>>> make
>>> 3 meg RN.
>
> The MCR 01 has a two foot chord wing, and the four seater we built has a 3
> foot chord.
>
>
> Concerning the Delta Dyke, one of my buddy owns one, and it is certainly
> not an answer to the original poster's requirements. On the contrary, it
> is a dog in flight, and very tricky. Deltas are definitely not a corrrect
> solution to any slow airplane.
>
> Regards,
> Gilles Thesee
> Grenoble, France
> http://contrails.free.fr

Hi Gerry,


> Thanks for your response, Gilles. A bit of clarification, perhaps. This is
> not really a design to fullfill a mission. It's more of a "why not"
> exercise.

Understand

The very short wingspan is the only real design criteria, and it
> is just my idea rather than a definite need anyone has.

OK. Just out of curiosity, is the short span intended for flight
"requirements" (landing between telephone poles...), or storage
considerations ? Not the same, of course, since for precise landings,
handling qualities may be of prime importance.

Or maybe is it just for the fun of short span ?


The MCR 01 is a
> very interesting design, but with a wingspan of over 20 feet it doesn't fit
> my plan. Consider that if you made it a 10 foot span biplane it would
> perhaps fit the bill?? I could restate it this way, if you divided the 20
> foot wingspan of the MCR 01 into two wings either tandem or stacked would it
> provide similar performance? How about 4 10 foot wings with one foot chord?
> I don't really know the answer, I'm just brainstorming to see if anyone else
> knows the answer.

I believe that by stacking wings, you'll end up with a much different
airplane.
By the way, really short chord wings work very well, provided the design
is correct.
French aerodynamicist Michel Colomban designed the Cri Cri 10 ft span, 1
ft chord single seater 25 years ago, with really nice flight behavior.
His last project will fly shortly with about 1.5 ft chord.

I seem to remember having seen a really short span American design,
which flew in the fifties or sixties. That was in an old issue of
"Popular Mechanics"

Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr


>
>

("GTH" wrote)
> French aerodynamicist Michel Colomban designed the Cri Cri 10 ft span, 1
> ft chord single seater 25 years ago, with really nice flight behavior.


Wingspan: 16.1 ft (4.9 m)
Maiden flight: 1973.

Cri-Cri links:

http://www.aerospaceweb.org/question/planes/q0275.shtml

http://www.pbase.com/kerosen/image/32381548

http://www.pbase.com/kerosen/image/32381546

http://flight.cz/cricri/english/cri-cri-photos-pictures.php

http://flight.cz/cricri/english/cri-cri-technical-description.php
Cri-Cri specs

http://flight.cz/cricri/english/cri-cri-articles.php
Good articles. One from 1974 and one from 1982.

http://en.wikipedia.org/wiki/Cri-cri
Wikipedia - Cri-Cri.

http://www.cricri.co.uk/

<http://www.airliners.net/search/photo.search?aircraft_genericsearch=Colomban%20MC-15%20Cri%20Cri%20(Cricket)&distinct_entry=true>
Airliners.net (3 pages of Cri-Cri's)

http://www.cricri-mc15.clan.st/


Montblack

They "all" are here.... perhaps not the safest aerial vehicles made?

http://www.aerospaceweb.org/question/design/q0214.shtml

JP


> I seem to remember having seen a really short span American design, which
> flew in the fifties or sixties. That was in an old issue of "Popular
> Mechanics"
>
> Regards,
> Gilles Thesee
> Grenoble, France
> http://contrails.free.fr
>
>
>>

Great link, thanks.
Gerry
"JP" > wrote in message
...
> They "all" are here.... perhaps not the safest aerial vehicles made?
>
> http://www.aerospaceweb.org/question/design/q0214.shtml
>
> JP
>
>
>> I seem to remember having seen a really short span American design, which
>> flew in the fifties or sixties. That was in an old issue of "Popular
>> Mechanics"
>>
>> Regards,
>> Gilles Thesee
>> Grenoble, France
>> http://contrails.free.fr
>>
>>
>>>
>

"GTH" > wrote in message
...
> Hi Gerry,
>
>
>> Thanks for your response, Gilles. A bit of clarification, perhaps. This
>> is not really a design to fullfill a mission. It's more of a "why not"
>> exercise.
>
> Understand
>
> The very short wingspan is the only real design criteria, and it
>> is just my idea rather than a definite need anyone has.
>
> OK. Just out of curiosity, is the short span intended for flight
> "requirements" (landing between telephone poles...), or storage
> considerations ? Not the same, of course, since for precise landings,
> handling qualities may be of prime importance.
>
> Or maybe is it just for the fun of short span ?

That's it. Folding doesn't serve the purpose.
I think the whole thing is inspired by an episode of a tv series call
"galactica" or something of the sort where they had flyable motorcycles.

Gerry
>
>
> The MCR 01 is a
>> very interesting design, but with a wingspan of over 20 feet it doesn't
>> fit my plan. Consider that if you made it a 10 foot span biplane it
>> would perhaps fit the bill?? I could restate it this way, if you divided
>> the 20 foot wingspan of the MCR 01 into two wings either tandem or
>> stacked would it provide similar performance? How about 4 10 foot wings
>> with one foot chord? I don't really know the answer, I'm just
>> brainstorming to see if anyone else knows the answer.
>
> I believe that by stacking wings, you'll end up with a much different
> airplane.
> By the way, really short chord wings work very well, provided the design
> is correct.
> French aerodynamicist Michel Colomban designed the Cri Cri 10 ft span, 1
> ft chord single seater 25 years ago, with really nice flight behavior.
> His last project will fly shortly with about 1.5 ft chord.
>
> I seem to remember having seen a really short span American design, which
> flew in the fifties or sixties. That was in an old issue of "Popular
> Mechanics"
>
> Regards,
> Gilles Thesee
> Grenoble, France
> http://contrails.free.fr
>
>
>>

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. 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
Hi, Gerry! Just remember this: if you take someone's word that
something won't work, you've only learned to pass that off as fact in
the future, and thus contribute to possible anti-knowledge and myths.
However, if you read as much as you can about a subject, then try it
yourself, even if it doesn't work, you'll know why. Go to www.mbda.net
and click on one of the little symbols in the lower left to get
"search", then put in Diamond back". A very interesting joined-wing,
extendable-wing concept!

ELIPPSE wrote:
> 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. 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
> Hi, Gerry! Just remember this: if you take someone's word that
> something won't work, you've only learned to pass that off as fact in
> the future, and thus contribute to possible anti-knowledge and myths.
> However, if you read as much as you can about a subject, then try it
> yourself, even if it doesn't work, you'll know why. Go to www.mbda.net
> and click on one of the little symbols in the lower left to get
> "search", then put in Diamond back". A very interesting joined-wing,
> extendable-wing concept!
>
Gerry,
Try NASA CR-178163 'Weight estimation techniques for composite
airplanes in general aviation industry'. Published 1986. While the title
says that it is for weight estimation, the report goes into pretty great
detail about various wing configurations, straight, canard, biplane/dual
wing, and swept forward/rearward and joined wing. In fact, it is the
first report that I can recall ever seeing that did any actual analysis
on joined wings. Lots of graphs showing the relative performance of
differing staggers and separations. Sounds like it's just what you are
looking for.

Morgans wrote:

> "flybynightkarmarepair" > wrote
>
>
>>This is an admittedly arbitrary distinction. The cabin on a Dyke Delta
>>is, again, IMHO, not well integrated into the fuselage/wing - MY
>>definition of a lifting body is that it's ALL an integrated whole.
>
>
> So, in your opinion, the Hyper Bipe is not a lifting body? It provides
> substantial lift, therefore, it is a lifting body, in everyone's view,
> except yours.
>
> I submit that you are incorrect.

Well, so does the Tailwind.

But the trick is, alla these have - well - wings!

Stall speeds???

I believe that these aircrafts are the ones having the Vso and Vne far too
close to each other :-)

I would be more worried about the actual glide ratio that may beat even the
space shuttle and that's scary. An engine out landing flare might be an
experience of a life time?

JP


"cavelamb" > wrote in
link.net...
> JP wrote:
>
>> They "all" are here.... perhaps not the safest aerial vehicles made?
>>
>> http://www.aerospaceweb.org/question/design/q0214.shtml
>>
>> JP
>>
> Far Out, JP.
>
> But they didn't show weights or stall speeds...
>

"ELIPPSE" > wrote in message
ups.com...
>
> 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.
>> 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
> Hi, Gerry! Just remember this: if you take someone's word that
> something won't work, you've only learned to pass that off as fact in
> the future, and thus contribute to possible anti-knowledge and myths.
> However, if you read as much as you can about a subject, then try it
> yourself, even if it doesn't work, you'll know why. Go to www.mbda.net
> and click on one of the little symbols in the lower left to get
> "search", then put in Diamond back". A very interesting joined-wing,
> extendable-wing concept!
>

Very interesting, thanks.
Gerry