Tandem-wing Airplanes

"Morgans" wrote in
:


"Bertie the Bunyip" wrote

Nope, it's a pisitive stagger biplane.

That's strange. Every positive stagger biplane I have looked at had
the top wing with a couple degrees more incidence than the lower wing.
Know why it is like the opposite?


Nope, almost never, in fact. The reason being that the bottom wing's
flow is affected by the top's. I'm guessing you thought they had the top
wing at a higher incidence probably because you heard that the top wing
should stall first to ensure a stable stall, which is patly true, but
that doesn't factor in the airflow in the "slot" between the wings,
which effectively lowers the angle of attack of the lower wing even
though it's incidence is higher than the top. Likewise the stab is
affected, and though a negative angle of attack is required for
stability, the airflow around the tail is affected by the wings and a
bit of down stabiliser is called for. Most guys find that the incidence
on the plans isn't enough, in fact.


Well, some guys have done this, but I'm not that crazy about the
piper jackscrew system in an airplane that will be turned up side
down. The plan is to have it hinged at the rear as you suggest, and
then have a attachment at the front that's shimmable and get it right
that way.

You could do it without using a jackscrew, I would think. How about
something like a cam on each side, with a shaft turning a cam on each
side, and a belcrank to turn the shaft. You could limit the range of
motion possible, so that even if something broke, it would be flyable.
I understand not wanting to trust a jackscrew.

It would probably add some complexity and weight, though, but it would
be an advantage for top speed, I would think.


What 86 instead of 85? Nah, weight is all impertant in this airplnae
since the power will be low. Also simplicity. The bits for the
adjustable incidence are already in place, anyway.. Never head of a cam
system before. Should work ok, though, once no slop was allowed.
In any case this is a traditional airplane using all traditional
materials. The only concessions to modernity I can think of are the disc
brakes and the nylon rags. Aside from that, it's a 1930 airplane in
every way.


Bertie

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote :





"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an experimenter. The
rocket
man posted som salient stuff there and understanding the relationship
between CG and the aerodynamic center is a very useful thing for a
builder.
Not strictly neccesary, of course, but definitely nice to know. Less
so for
a pilot...

I feel I have a good grip on the relationship between CG an AC for
conventional planforms. I have no interest in canards or tandem
lifting wings.

I did pay a bit more attention to a few of the posts, though, and his
being some of them.

Well, it's relevant to conventional airplanes in an indirect sort of way,
which is my point. If you truly understand the principles involved, you
then thoroughly understand enough to trim your homebuilt. My own airplane
is notorious for needing stab adjustments after the first flight. A real
PITA since the stab is welded into position ( I plan to make mine
adjustable with shims) Now, the stab on my airplane has a negative
incidence, while the top wing is set at zero and the bottom is set at plus
2 degrees. Doesn't seem to add up, does it? The stab is flat plate, BTW.
So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......


*****************************************

Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Big John

"Bertie the Bunyip" wrote in message ...


Well, it's relevant to conventional airplanes in an indirect sort of way,
which is my point. If you truly understand the principles involved, you
then thoroughly understand enough to trim your homebuilt. My own airplane
is notorious for needing stab adjustments after the first flight. A real
PITA since the stab is welded into position ( I plan to make mine
adjustable with shims) Now, the stab on my airplane has a negative
incidence, while the top wing is set at zero and the bottom is set at plus
2 degrees. Doesn't seem to add up, does it? The stab is flat plate, BTW.
So, waht's all that about?



Bertie

Probably the incidences are set up that way to reduce roll couple in knife edge, an attempt to keep each axis separate
from the others...

On Feb 5, 5:53*pm, Big John wrote:


Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Big John

Based on what I learned over in the Why Airplanes Fly thread, I guess
it cost a lot of money!

Phil

"Blueskies" wrote in
t:

"Bertie the Bunyip" wrote in message
...


Well, it's relevant to conventional airplanes in an indirect sort of
way, which is my point. If you truly understand the principles
involved, you then thoroughly understand enough to trim your
homebuilt. My own airplane is notorious for needing stab adjustments
after the first flight. A real PITA since the stab is welded into
position ( I plan to make mine adjustable with shims) Now, the stab
on my airplane has a negative incidence, while the top wing is set at
zero and the bottom is set at plus 2 degrees. Doesn't seem to add up,
does it? The stab is flat plate, BTW. So, waht's all that about?



Bertie

Probably the incidences are set up that way to reduce roll couple in
knife edge, an attempt to keep each axis separate from the others...



Nope. It's beacuse the flow from the fairly large wings on thei relatively
short coupled airplane is flowing down at a significant angle when it
reaches the tail.


Bertie

Big John wrote in
:

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote
:





"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an experimenter.
The rocket
man posted som salient stuff there and understanding the
relationship between CG and the aerodynamic center is a very
useful thing for a builder.
Not strictly neccesary, of course, but definitely nice to know.
Less so for
a pilot...

I feel I have a good grip on the relationship between CG an AC
for
conventional planforms. I have no interest in canards or tandem
lifting wings.

I did pay a bit more attention to a few of the posts, though, and
his being some of them.

Well, it's relevant to conventional airplanes in an indirect sort of
way, which is my point. If you truly understand the principles
involved, you then thoroughly understand enough to trim your
homebuilt. My own airplane is notorious for needing stab adjustments
after the first flight. A real PITA since the stab is welded into
position ( I plan to make mine adjustable with shims) Now, the stab
on my airplane has a negative incidence, while the top wing is set
at zero and the bottom is set at plus 2 degrees. Doesn't seem to add
up, does it? The stab is flat plate, BTW. So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......


*****************************************

Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Ponies!


Actually I thnk it had more to do with the careful attention to the
fillets and a relatively small frontal area on the fuse. Probably used a
fairly thin wing section as well.


They just got it all right with that one, didn't they?


Bertie

On Wed, 6 Feb 2008 06:02:58 +0000 (UTC), Bertie the Bunyip
wrote:

Big John wrote in
:

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote
:





"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an experimenter.
The rocket
man posted som salient stuff there and understanding the
relationship between CG and the aerodynamic center is a very
useful thing for a builder.
Not strictly neccesary, of course, but definitely nice to know.
Less so for
a pilot...

I feel I have a good grip on the relationship between CG an AC
for
conventional planforms. I have no interest in canards or tandem
lifting wings.

I did pay a bit more attention to a few of the posts, though, and
his being some of them.

Well, it's relevant to conventional airplanes in an indirect sort of
way, which is my point. If you truly understand the principles
involved, you then thoroughly understand enough to trim your
homebuilt. My own airplane is notorious for needing stab adjustments
after the first flight. A real PITA since the stab is welded into
position ( I plan to make mine adjustable with shims) Now, the stab
on my airplane has a negative incidence, while the top wing is set
at zero and the bottom is set at plus 2 degrees. Doesn't seem to add
up, does it? The stab is flat plate, BTW. So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......


*****************************************

Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Ponies!


Actually I thnk it had more to do with the careful attention to the
fillets and a relatively small frontal area on the fuse. Probably used a
fairly thin wing section as well.


They just got it all right with that one, didn't they?


Bertie


************************************************** **************
Bertie

Thought someone would talk about the negative stagger and inter action
between the two wings and rigging, etc )

Almost bought one, one time. Had a friend who did buy a run out one
and had overhauled and recovered in Panama when we were stationed
there. There was a shop who did a excellent job for bottom dollar
price. It took them about 6 months to do between other jobs to keep
price down. Can't find those economical places any more even over
seas.

Big John

On Feb 6, 10:07*pm, Big John wrote:
On Wed, 6 Feb 2008 06:02:58 +0000 (UTC), Bertie the Bunyip
wrote:





Big John wrote in
:

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote
:

"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an experimenter.
The rocket
man posted som salient stuff there and understanding the
relationship between CG and the aerodynamic center is a very
useful thing for a builder.
Not strictly neccesary, of course, but definitely nice to know.
Less so for
a pilot...

*I feel I have a good grip on the relationship between CG an AC
*for
conventional planforms. *I have no interest in canards or tandem
lifting wings.

I did pay a bit more attention to a few of the posts, though, and
his being some of them.

Well, it's relevant to conventional airplanes in an indirect sort of
way, which is my point. If you truly understand the principles
involved, you then thoroughly understand enough to trim your
homebuilt. My own airplane is notorious for needing stab adjustments
after the first flight. A real PITA since the stab is welded into
position ( I plan to make mine adjustable with shims) Now, the stab
on my airplane has a negative incidence, while the top wing is set
at zero and the bottom is set at plus 2 degrees. Doesn't seem to add
up, does it? The stab is flat plate, BTW. So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......

*****************************************

Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Ponies!

Actually I thnk it had more to do with the careful attention to the
fillets and a relatively small frontal area on the fuse. Probably used a
fairly thin wing section as well.

They just got it all right with that one, didn't they?

Bertie

************************************************** **************
Bertie

Thought someone would talk about the negative stagger and inter action
between the two wings and rigging, etc *)

I would if I knew! You'd have to ask someone with a lot more knowledge
than me for a definitive answer. My own view is that like all
airplanes ever built it was a case of comprimise and integration. The
deisrability of a stagger and the slightly better negative stagger
configuration ( for drag, if not lift) went nicely hand in hand with
the desire to increase, if only slightly, in flight visibility ( over
say, a Waco UIC) and tied in well with the wing mounted gear which
allowed a relatively simple retract system. It was simply a well
thought out airplnae which balanced the pros and cons of each element
of the configuration and brougth them all together into one slick
machine. I'm struggling to think of something comparable that did it
quite so beautifully. Having siad that, if you put that and a WACO SRE
in front of me, I think I'd choose the WACO


Almost bought one, one time. Had a friend who did buy a run out one
and had overhauled and recovered in Panama when we were stationed
there. There was a shop who did a excellent job for bottom dollar
price. It took them about 6 months to do between other jobs to keep
price down. * Can't find those economical places any more even over
seas.

Nice. Kicking yourself now, eh? A friend of mine bought a project B17
with the Jake in it and gave up on it after a few years and sold it. I
was really hoping to get to fly it!

Bertie

On Thu, 7 Feb 2008 14:41:38 -0800 (PST), Bertie the Bunyip
wrote:

On Feb 6, 10:07*pm, Big John wrote:
On Wed, 6 Feb 2008 06:02:58 +0000 (UTC), Bertie the Bunyip
wrote:





Big John wrote in
:

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote
:

"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an experimenter.
The rocket
man posted som salient stuff there and understanding the
relationship between CG and the aerodynamic center is a very
useful thing for a builder.
Not strictly neccesary, of course, but definitely nice to know.
Less so for
a pilot...

*I feel I have a good grip on the relationship between CG an AC
*for
conventional planforms. *I have no interest in canards or tandem
lifting wings.

I did pay a bit more attention to a few of the posts, though, and
his being some of them.

Well, it's relevant to conventional airplanes in an indirect sort of
way, which is my point. If you truly understand the principles
involved, you then thoroughly understand enough to trim your
homebuilt. My own airplane is notorious for needing stab adjustments
after the first flight. A real PITA since the stab is welded into
position ( I plan to make mine adjustable with shims) Now, the stab
on my airplane has a negative incidence, while the top wing is set
at zero and the bottom is set at plus 2 degrees. Doesn't seem to add
up, does it? The stab is flat plate, BTW. So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......

*****************************************

Lets throw the D-17 in the discussion and why it was so fast in it's
time frame.

Ponies!

Actually I thnk it had more to do with the careful attention to the
fillets and a relatively small frontal area on the fuse. Probably used a
fairly thin wing section as well.

They just got it all right with that one, didn't they?

Bertie

************************************************** **************
Bertie

Thought someone would talk about the negative stagger and inter action
between the two wings and rigging, etc *)

I would if I knew! You'd have to ask someone with a lot more knowledge
than me for a definitive answer. My own view is that like all
airplanes ever built it was a case of comprimise and integration. The
deisrability of a stagger and the slightly better negative stagger
configuration ( for drag, if not lift) went nicely hand in hand with
the desire to increase, if only slightly, in flight visibility ( over
say, a Waco UIC) and tied in well with the wing mounted gear which
allowed a relatively simple retract system. It was simply a well
thought out airplnae which balanced the pros and cons of each element
of the configuration and brougth them all together into one slick
machine. I'm struggling to think of something comparable that did it
quite so beautifully. Having siad that, if you put that and a WACO SRE
in front of me, I think I'd choose the WACO


Almost bought one, one time. Had a friend who did buy a run out one
and had overhauled and recovered in Panama when we were stationed
there. There was a shop who did a excellent job for bottom dollar
price. It took them about 6 months to do between other jobs to keep
price down. * Can't find those economical places any more even over
seas.

Nice. Kicking yourself now, eh? A friend of mine bought a project B17
with the Jake in it and gave up on it after a few years and sold it. I
was really hoping to get to fly it!

Bertie
************************************************** *************************

You don't have to rub it in (

It takes a PILOT to fly one with it's take off and landing
characteristics. Not a beginners aircraft. The WACO
would be a more comfortable and relaxing bird to fly I'm
sure but wouldn't attract the crowd of gawkers when you
landed at a GA airport ).

Big John

Big John wrote in
:

On Thu, 7 Feb 2008 14:41:38 -0800 (PST), Bertie the Bunyip
wrote:

On Feb 6, 10:07*pm, Big John wrote:
On Wed, 6 Feb 2008 06:02:58 +0000 (UTC), Bertie the Bunyip
wrote:





Big John wrote in
:

On Mon, 4 Feb 2008 18:06:56 -0800 (PST), "Ken S. Tucker"
wrote:

On Feb 4, 4:39 pm, Bertie the Bunyip wrote:
"Morgans" wrote
:

"Bertie the Bunyip" wrote

well, it must be at least a bit interesting for an
experimenter. The rocket
man posted som salient stuff there and understanding the
relationship between CG and the aerodynamic center is a very
useful thing for a builder.
Not strictly neccesary, of course, but definitely nice to
know. Less so for
a pilot...

*I feel I have a good grip on the relationship between CG an
AC *for
conventional planforms. *I have no interest in canards or
tandem lifting wings.

I did pay a bit more attention to a few of the posts, though,
and his being some of them.

Well, it's relevant to conventional airplanes in an indirect
sort of way, which is my point. If you truly understand the
principles involved, you then thoroughly understand enough to
trim your homebuilt. My own airplane is notorious for needing
stab adjustments after the first flight. A real PITA since the
stab is welded into position ( I plan to make mine adjustable
with shims) Now, the stab on my airplane has a negative
incidence, while the top wing is set at zero and the bottom is
set at plus 2 degrees. Doesn't seem to add up, does it? The
stab is flat plate, BTW. So, waht's all that about?

Bertie

I hear a candiate screamin for the Darwin Awards.
Leave flying to us pro's, you stay in outhouse.
......

*****************************************

Lets throw the D-17 in the discussion and why it was so fast in
it's time frame.

Ponies!

Actually I thnk it had more to do with the careful attention to the
fillets and a relatively small frontal area on the fuse. Probably
used a fairly thin wing section as well.

They just got it all right with that one, didn't they?

Bertie

************************************************** **************
Bertie

Thought someone would talk about the negative stagger and inter
action between the two wings and rigging, etc *)

I would if I knew! You'd have to ask someone with a lot more knowledge
than me for a definitive answer. My own view is that like all
airplanes ever built it was a case of comprimise and integration. The
deisrability of a stagger and the slightly better negative stagger
configuration ( for drag, if not lift) went nicely hand in hand with
the desire to increase, if only slightly, in flight visibility ( over
say, a Waco UIC) and tied in well with the wing mounted gear which
allowed a relatively simple retract system. It was simply a well
thought out airplnae which balanced the pros and cons of each element
of the configuration and brougth them all together into one slick
machine. I'm struggling to think of something comparable that did it
quite so beautifully. Having siad that, if you put that and a WACO SRE
in front of me, I think I'd choose the WACO


Almost bought one, one time. Had a friend who did buy a run out one
and had overhauled and recovered in Panama when we were stationed
there. There was a shop who did a excellent job for bottom dollar
price. It took them about 6 months to do between other jobs to keep
price down. * Can't find those economical places any more even over
seas.

Nice. Kicking yourself now, eh? A friend of mine bought a project B17
with the Jake in it and gave up on it after a few years and sold it. I
was really hoping to get to fly it!

Bertie
************************************************** ********************
*
****

You don't have to rub it in (

It takes a PILOT to fly one with it's take off and landing
characteristics. Not a beginners aircraft. The WACO
would be a more comfortable and relaxing bird to fly I'm
sure but wouldn't attract the crowd of gawkers when you
landed at a GA airport ).


I think I could manage a 17 OK, It's the performance of the WACO I'd
prefer, I think ( runway and climb) And I prefer it's looks. Having said
that it;s like choosing between two supermodels..


Bertie