Fast glass biplanes

"Jay" wrote ...
There was someone that commented that if 2 lifting surfaces made
sense, you'd see the 777 with 2 wings because they're Boeing and have
lots of money and super human engineers. I've worked for lots of
companies like Boeing (but not them because they tried to low ball me)
and they're made up of regular guys like you and me. Many of them
have interests and responsibility outside of designing the best
aircraft ever, and really just want to pay their bills and go home and
have a beer. You work as one guy in a huge machine where decisions
are often made on what's politicaly the best answer rather than what's
technically best. You get one tiny componant of this huge project.
These kinds of organizations often punish risk taking in that there is
no upside pay-off if you're right. But if you're wrong, and it was
because you did something different than before, you get hammered. So
the larger the project, the more conservative the approach tends to
be. Remember, bean counters hate risk of any kind.

Bull****, Jay.

I worked for several years as an engineer in Boeing's Aero Staff.
Everything you just said is wrong. The people that design wings at Boeing
use the best technology available that's consistant with the production
materials that are available. They don't design on the basis of some
political whim. They don't design biplanes because it's easy to show
mathematically that the mutual interference between the circulation of the
two wings decreases the efficiency of both wings.

You seem to have strange theory that just because something isn't done it
must be a good thing to try. Subsonic aerodynamics was well explored by
World War II. Much of transonic and supersonic flow was understood shortly
after. If you think that you've come up with something new that just means
you don't understand why thinks work. If you want do to something different
just to be different go ahead, but it will be an inferior product and
possibly dangerous. Your current design has at least three fatal flaws.
You need to open some books and understand the theory of flight before you
start designing airplanes.

Rich

Dave Hyde wrote:
snip

Biplanes are a simple,
but inefficient, way of getting more lift from wing area
when an increase in span is not feasible. The are not, nor
in general are they intended to be, "low drag."


You mentioned the interference drag, so how far do wings
need to be vertically separated for a given airfoil
and stagger for this effect to be negligable?


*negligible?* Some *large* fraction of the span. At a minimum.
snip

Dave 'usenet wind tunnel' Hyde


Here's some pretty pictures of biplane wing pressure interaction from
the CFD tool that Peter Garrison sells:

http://www.melmoth2.com/texts/CFD.htm

B.S.

On 17 Nov 2003 10:50:07 -0800, (Jay) wrote:

But why not take each of those sailplane wings and put one
over the top of the other? You mentioned the interference drag, so
how far do wings need to be vertically separated for a given airfoil
and stagger for this effect to be negligable?



jay
I seem to recall something that tried this.
the dynamics of the thing bought it undone.
as the forward wind flexes it alters the flow over the rear wing and
induces flexing. the thing can self destruct if you get the thing
wrong.

Stealth (everything is aeroelastic to some degree) Pilot

On 15 Nov 2003 09:17:59 -0800, (Jay) wrote:

Apart from the Quickie group of planes why aren't there more fast
biplanes? The quickies aren't exactly biplanes I know. It would
appear that 2 short wings can be built lighter than one long one since
the moment arm is half as long for the shorter wing pair. No struts
used because of drag, just short cantilever wings. You'd have a more
compact airplane that way with less weight that had the same drag as
an equal wing area monoplane.


I read once that a computer program exploring optimum biplane and
canard setups popped out the optimum setup as one where the forward
canard was 5 times the span of the rear one with the cg at 25% of the
chord of the forward canard.
I accept that that maybe an urban legend but put with the success that
mike arnold experienced with his AR5 you might just have an answer.

as well have a look at formula 1 aircraft designs. they are about as
competitive as you can get and on basically the same engine they are
now 100mph faster than 50 years ago.
havent seen a canard or biplane last very long among them.

Stealth Pilot

You're missing the point of the modern canard. They were developed to be a
stall/spin-proof alternitave to the conventional wing-tail layout. An
example: two friends built glass airplanes, one a Glasair with a 150 hp Lyc
and the other a Long-EZ with a 150 hp Lyc, both with fixed-pitch wood
props.. Flat out, the Glasair was faster, but only slightly -- 215 vs. 210
mph. Seems to me to be a small price to pay for an aircraft that won't
stall or spin. And if the engine quits, you want to be in the Long-EZ, not
the Glasair -- it glides much better.

Fred in Florida

"Stealth Pilot" wrote in message
news
On 15 Nov 2003 09:17:59 -0800, (Jay) wrote:

Apart from the Quickie group of planes why aren't there more fast
biplanes? The quickies aren't exactly biplanes I know. It would
appear that 2 short wings can be built lighter than one long one since
the moment arm is half as long for the shorter wing pair. No struts
used because of drag, just short cantilever wings. You'd have a more
compact airplane that way with less weight that had the same drag as
an equal wing area monoplane.


I read once that a computer program exploring optimum biplane and
canard setups popped out the optimum setup as one where the forward
canard was 5 times the span of the rear one with the cg at 25% of the
chord of the forward canard.
I accept that that maybe an urban legend but put with the success that
mike arnold experienced with his AR5 you might just have an answer.

as well have a look at formula 1 aircraft designs. they are about as
competitive as you can get and on basically the same engine they are
now 100mph faster than 50 years ago.
havent seen a canard or biplane last very long among them.

Stealth Pilot

And if the engine quits, you want to be in the Long-EZ, not
the Glasair -- it glides much better.

That's a questionable statement!!

Compare the following for survivability in an accident:
* slower touchdown speed
* deformation of the structure to absorb energy
* lack of intrusions into the crew area (survivable space)

Looks to me like the Glasair would be much more survivable... not that
I'm personally interested in running the experiments

Ed "I'm supposed to teach a class on this stuff next term" Wischmeyer

"Ed Wischmeyer" wrote in message
...
And if the engine quits, you want to be in the Long-EZ, not
the Glasair -- it glides much better.

That's a questionable statement!!

Compare the following for survivability in an accident:
* slower touchdown speed
* deformation of the structure to absorb energy
* lack of intrusions into the crew area (survivable space)

Looks to me like the Glasair would be much more survivable... not that
I'm personally interested in running the experiments

Okay Ed, I'll take the bait. I assume you're taking issue with which
airplane you'd rather be in, not which one glides better. With engine off
and prop stopped and 80kn, a Long will glide losing 5-700 fpm. Tough to
match that in a Glasair. This would give the Long alarger raidus in which
to find a suitable landing place.

Slower touchdown speed? Unless at a very low gross weight, a Long would be
hard-pressed to get under 60 kn. It's part of the design, I assume, to
assure that the main wong won't stall. The Glasair could probably do
better.

Deformation of the structure? They're both glass -- don't know how you
could say one was better than the other.

Lack of intrusions? The Long's got the nosegear crank, but the Glasair's
got the sticks ... uh ... down *there*. Which is worse? I don't know.

As I said before, the whole reason for a canard airplane is for it's stall-
and spin-limiting abilities, not because it is "more efficient."

On Sun, 16 Nov 2003 20:25:33 +0000, Fred in Florida wrote:


"Ed Wischmeyer" wrote in message
...
And if the engine quits, you want to be in the Long-EZ, not the
Glasair -- it glides much better.

That's a questionable statement!!

Compare the following for survivability in an accident: * slower
touchdown speed
* deformation of the structure to absorb energy * lack of intrusions
into the crew area (survivable space)

Okay Ed, I'll take the bait. I assume you're taking issue with which
airplane you'd rather be in, not which one glides better. With engine off
and prop stopped and 80kn, a Long will glide losing 5-700 fpm. Tough to
match that in a Glasair. This would give the Long alarger raidus in which
to find a suitable landing place.

Lack of intrusions? The Long's got the nosegear crank, but the Glasair's
got the sticks ... uh ... down *there*. Which is worse? I don't know.


If I'm going to be in a crash, and it isn't on flat ground, I would rather
have the engine ahead of me than behind me. I figure it has a bit less
chance of ending up in the cockpit that way.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

On Sun, 16 Nov 2003 15:57:45 +0800, Stealth Pilot
wrote:

I read once that a computer program exploring optimum biplane and
canard setups popped out the optimum setup as one where the forward
canard was 5 times the span of the rear one with the cg at 25% of the
chord of the forward canard.

Actually, that was contained in an article called "Canard Canard" in
AEROSPACE AMERICA magazine, back in the early '90s. I've posted about it
here in RAH several times, that's probably where you remember it from.
Used to have the article rattling around the office, somewhere.

Canard designs are just a different approach to the compromises necessary
for aircraft development. What they gain in eliminating the horizontal
stabilizer downforce, they lose in other areas.

Wanttaja Ron

On Sun, 16 Nov 2003 18:08:58 GMT, Ron Wanttaja
wrote:

On Sun, 16 Nov 2003 15:57:45 +0800, Stealth Pilot
wrote:

I read once that a computer program exploring optimum biplane and
canard setups popped out the optimum setup as one where the forward
canard was 5 times the span of the rear one with the cg at 25% of the
chord of the forward canard.

Actually, that was contained in an article called "Canard Canard" in
AEROSPACE AMERICA magazine, back in the early '90s. I've posted about it
here in RAH several times, that's probably where you remember it from.
Used to have the article rattling around the office, somewhere.

Canard designs are just a different approach to the compromises necessary
for aircraft development. What they gain in eliminating the horizontal
stabilizer downforce, they lose in other areas.

Wanttaja Ron

see we remember what you write ron. :-)

back to the guys original question, I take it that the "lose in other
areas" is why you dont see them as racers mixing it with the less
compromised.

Stealth Pilot