questions on multi-wing planforms

"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?



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

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


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



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-...s-pictures.php

http://flight.cz/cricri/english/cri-...escription.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