Fast glass biplanes

alexy wrote:
(Jay) wrote:
Instead of running numbers on Excel with formulas filled with fudge
factors from experimental data taken 70 years ago, I think I'm going
to throw some wings on my FEA computer model and let the computer take
care of the algebra at 2.4GHz.

Now THAT is scary. Someone who thinks a computer model is a substitute
for learning fundamentals (and is impressed by the speed if his PC's
processorVBG) is a huge danger to himself. If you do get into the
build mode, I hope you will try out your ideas on an RC model first.


But learn about scale effects, or the model work isn't useful.

Ben "Osborne Reynolds" Sego

ChuckSlusarczyk wrote:
In article .net, Ben Sego
says...
other than Jim Campbell, he liked it...

Corky Scott

Well, I'm sold then!


He likes anything that he thinks will lead to some ad money :-) He only stops
liking them when they stop the ads. zoom likes it and jaun will probably rebuild
it .....but never fly it. LOL!!!

Chuck(believer in 70 year old data) S


I understand it can be difficult to cancel an ad. Perhaps people aren't
speaking clearly and forthrightly enought to them...er...him.

Ben "governing myself" Sego

Jay wrote:

*sigh*

Instead of running numbers on Excel with formulas filled with fudge
factors from experimental data taken 70 years ago, I think I'm going
to throw some wings on my FEA computer model and let the computer take
care of the algebra at 2.4GHz.

I give up. Good luck, and please post or publish your results
when you're done. The world awaits.

Dave 'Pontius Pilot' Hyde
++++++++++++++++++++++++++++++++++++

Nice try, Pontius.
However, this outcome was inevitable.
Kinda like with his brother, Latchless. g


Barnyard BOb --

On 19 Nov 2003 10:56:41 -0800, (Jay) wrote:

:Instead of running numbers on Excel with formulas filled with fudge
:factors from experimental data taken 70 years ago, I think I'm going
:to throw some wings on my FEA computer model and let the computer take
:care of the algebra at 2.4GHz.

There you go. Exactly what Alan Shaw did with the Atlantica. It
turned out great. And the Prescott Pusher, designed entirely with
McDonnald Douglass CAD. A terrific airplane. A computer can't go
wrong.

BTW, if you aren't using a Pentium 4 3.06GHz 533Mhz 512K Xeon at a
minumum, you aren't even a serious amateur.

(Bob Kuykendall) wrote in message

On a slightly different topic: Jay, when I was pointing you towards
joined-wing concepts in the earlier thread and also in private email,

I did get your e-mail, thank you for that. I have actually seen, but
not run, the models that are configured the way you describe.

I really wasn't trying to be snarky. I was trying to point out a
configuration that:

* Suggests a practical application for something like a biplane
configuration

* Has been studied enough to suggest that it offers, in theory at
least, some advantages over other configurations

* Is not well explored in physical hardware (NASA canceled their
proof-of-concept aircraft and put the AD-1 it was based on in the
Hiller museum)

* Would look relatively cool and unusual

Thanks, and best regards to all

Bob K.

Thanks Alexy,

I wasn't sure what the convention was in aero work for defining
"aspect", it doesn't really matter as long as everybody agrees on the
same definition! So I just took David's definition and went from
there.

Then in his next expresion said "span^2/aero", so I figured "AERO"
meant something that he hadn't defined, but I should have implicitly
known, and figured at this point it wasn't crucial to the discussion.

But this is the reason why I was trying to discuss relationships
before we got into botched algebra. I'm seem to be continually making
those kinds of errors so I end up doing everything 2 ways just to make
sure.


alexy wrote in message . ..
Dave Hyde wrote:

I think you have a fundamental misunderstanding of the basics here.
An infinte (span) wing has an aspect ratio of INFINITY, not zero.
LARGER aspect ratio is less drag.
Dave, to be fair to Jay, you did type

:The _definition_ of aspect ratio is chord/span

Of course, you immediately contradicted that by typing

r span^2/aero (they're equivalent)

which should have clued anyone in that you had inverted the first
expression.

Hey don't give up Dave, nobody said it would be easy. You haven't
convinced me not to run the model. But you have pointed out 2 things
I will look at more carefully:

1) Will the root/tip losses from 2 wings eat up any benefit from the
shorter/lighter spans? Are there tip treatments that diminish this?

2) What wing configuration can be used that minimizes mutual
interference between the 2 lifting surfaces.

Thanks!

p.s. I will post the results when I get them.

Dave Hyde wrote in message ...
Jay wrote:

*sigh*

Instead of running numbers on Excel with formulas filled with fudge
factors from experimental data taken 70 years ago, I think I'm going
to throw some wings on my FEA computer model and let the computer take
care of the algebra at 2.4GHz.

I give up. Good luck, and please post or publish your results
when you're done. The world awaits.

Dave 'Pontius Pilot' Hyde

Ben Sego wrote:



alexy wrote:
(Jay) wrote:
Instead of running numbers on Excel with formulas filled with fudge
factors from experimental data taken 70 years ago, I think I'm going
to throw some wings on my FEA computer model and let the computer take
care of the algebra at 2.4GHz.

Now THAT is scary. Someone who thinks a computer model is a substitute
for learning fundamentals (and is impressed by the speed if his PC's
processorVBG) is a huge danger to himself. If you do get into the
build mode, I hope you will try out your ideas on an RC model first.


But learn about scale effects, or the model work isn't useful.

Alternate responses:
1) Doh, of course. I forgot about that.
2) Well of course. I thought that was obvious.
3) Why did you assume that by RC model I meant one at other than 1:1
scale?
4) Yeah, but he was talking about wings with infinite span, so I
figured scaling didn't apply.

Honesty compels me to #1. Good catch.
--
Alex
Make the obvious change in the return address to reply by email.

It looks like Atlantica is still in development, they're using the
same software as I am for my dabbling.

Prescott's Pusher looks like it was pretty ordinary in terms of the
trade offs made (high stall speed), the computer used for that
development looks like it was for manufacturability (CAM) rather than
conducting experiments in aerodynamics. The twitchyness in pitch
people write about is obvious because of the distance between the
center of lift and the elevator, no mystery there. If they'd had the
tools available to the hobbiest today, they'd have been able to see it
before they built it.

Computers aren't perfect, they're programmed by people, with the same
assumptions and errors. But the throughput allows a different type of
analysis to be done than was previously available. Instead of trying
to find a closed form aproximation for a particular parameter of
flight, it allows you to model lots and lots of very simple phenomenon
which come together to produce some high level behaviour like a stall
or another unanticipated effect.

wrote in message . ..
On 19 Nov 2003 10:56:41 -0800, (Jay) wrote:

:Instead of running numbers on Excel with formulas filled with fudge
:factors from experimental data taken 70 years ago, I think I'm going
:to throw some wings on my FEA computer model and let the computer take
:care of the algebra at 2.4GHz.

There you go. Exactly what Alan Shaw did with the Atlantica. It
turned out great. And the Prescott Pusher, designed entirely with
McDonnald Douglass CAD. A terrific airplane. A computer can't go
wrong.

BTW, if you aren't using a Pentium 4 3.06GHz 533Mhz 512K Xeon at a
minumum, you aren't even a serious amateur.

In article , Dave Hyde wrote:
Jay wrote:

Okay, thanks for all that, I think you're missing some parentheses in
there because I'm getting a quad decker formula.

The formula is correct as written.

So with this theoretical wing of aspect approaching zero,
2 non-interfering wings of half span, would be essentially the
same lift and drag as one.

I think you have a fundamental misunderstanding of the basics here.
An infinte (span) wing has an aspect ratio of INFINITY, not zero.
LARGER aspect ratio is less drag.
Again, to make a successful break from the mouse-maze, you've
either got to have a sound grasp of the fundamentals or be
very lucky. Counting on luck does not instill confidence
(but sometimes produces interesting threads).

Most if not all of those X planes were R&D payed for by the you and
me, the tax payers of America. Its extremely rare for a large company
to take a "flyer" with their own money and reach very far forward.

Who pays is irrelevant. There have been and will continue to
be radical departures from the 'box' even by giants in the aerospace
industry. The simple fact that you are not aware of them does not
mean that they do not exist.

Dave 'to infinity...and beyond' Hyde

AHA! *THERE's* the proper explanation.

Twin wings, with aleph-sub-one aspect ratio _should_ out-perform a
(merely) 'infinite' AR wing. *snicker* chortle =+GUFFAW+=