questions on multi-wing planforms

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


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