epoxy aircraft seats?

On Sat, 29 Nov 2003 21:27:21 -0600, Big John wrote:

There was a group (don't remember who, could have been NASA????)
sometime after the War who ran tests on the mustang wing and concluded
it was not laminar. Not sure now if this was from wind tunnel tests or
computer simulation? Also not sure what their object was, maybe just
too much time on their hands?

Then again, I've heard that it's very difficult to get true laminar flow
for *any* type of construction...at least in the real world. A bit of
dirt, a fuel cap, a small dent from a dropped tool, a few bugs splattered
on the leading edge....

On the opposite side of the spectrum, I'm considering goofing around with
some homemade VGs on my Fly Baby next year. Figured I buy a batch of 1/4 -
1/2" aluminum angle and cut up a batch. Anybody have any rules of thumb
regarding size, placement, stupidity of the idea, etc.?

Ron Wanttaja

"Ron Wanttaja" wrote in message
...
On Sat, 29 Nov 2003 21:27:21 -0600, Big John wrote:

There was a group (don't remember who, could have been NASA????)
sometime after the War who ran tests on the mustang wing and concluded
it was not laminar. Not sure now if this was from wind tunnel tests or
computer simulation? Also not sure what their object was, maybe just
too much time on their hands?

Then again, I've heard that it's very difficult to get true laminar flow
for *any* type of construction...at least in the real world. A bit of
dirt, a fuel cap, a small dent from a dropped tool, a few bugs splattered
on the leading edge....

True. Arnold did his world-record run purposely in the early morning
before the bugs were out, and on a Sunday since most of them are
protestants.

I'm trying to remember which lam flow airfoil it was in one of the mags.
The Stallion, maybe? The pilot/designer wrote that he had a jolting hard
landing at Oshkosh because he had descended and flown into bug territory
altitude for the last several hundred miles and picked up a layer of them on
his leading edge, causing his stall speed to increase about 10 knots.


On the opposite side of the spectrum, I'm considering goofing around with
some homemade VGs on my Fly Baby next year. Figured I buy a batch of
1/4 -
1/2" aluminum angle and cut up a batch. Anybody have any rules of thumb
regarding size, placement, stupidity of the idea, etc.?

Ron Wanttaja

Larry Smith a écrit:


I'll give you another example --- Mike Arnold's 213 mph world
champion speedster, the AR-5. Do you believe that same airframe,
which is very light, btw, because of judicious (but not
vacuum-bagged) layups, could have
been made of aluminum? I don't. The AR-5 defeated the previous
world record-holder, which was an aluminum BD-5. Aluminum and
compound curves don't mix. Aluminum and laminar flow airfoils
don't mix either.
So I'd say that the composite aircraft 100 pounds heavier than the
RV-6 is faster on the same engine and prop combination. I may be
wrong. At least you can hide antennas inside the airframe.

Not taking anything away from 2024-T3, of course. Duralumin is
still a miracle material for aircraft construction. And, having
recorded the "From the Ground Up" series with Joe Schumacher and
Mark Annick, I'm envious of your RV-8 project.

I don't realy agree.... We kwon two airframe from same design:
The "Banbi" MC100, homebuilt from plans and the MCR01 kit (known as
Lafayette in USA).
The aluminium alloy homebuilt weight is 202kg, the carbon/epoxy kit
wieght is 232 all with Rotax 912 engine.
This plane is design by Michel Colomban, desinger of little twin
Cricri or Criquet. He designed bonded aluminium skin, realy good for
laminar flow and light weight and true homebuilt too.

By
--
MinCab F-PRAZ
Philippe Vessaire Ò¿Ó¬

"Larry Smith" wrote in message ...
"Lpmcatee356" wrote in message
...
where can I find construction details - howto files?

Try downloading the Quicke construction manual. It's not much more than a
seat
with wings.

www.finleynet.com


I used an ergonomically designed race-car seat as a mold and laid one up
using Rutan cloth and epoxy, then reinforced it with foam and a few more
layers of glass. The best way to learn about glass layups and molds is
reading Rutan's treatise on moldless foam construction and watching Mike
Arnold's AR-5 videotapes. Btw, the strength is not in the epoxy but in the
fiberglas. Or S-glass, or carbon fiber. However the resin matrix permits
the fibers to realize their strength.

At its website Cessna explains why it uses exclusively aluminum
construction. Cessna says there are too many unknowns regarding glass and
that aluminum is better. Well, aluminum IS better in some respects, but
glass is also better in many respects too. Fiberglas is easy to repair, it
lends itself nicely to compound curves, it does not corrode or fatigue like
aluminum, it is capable of absorbing more shock than aluminum, and its
strength-to-weight ratio cannot be beat.

Plus, when is the last time you saw a laminar flow wing made of aluminum?

You have to be very careful not to get your glass layup overweight. You
have to be very careful not to let your glass ship get hot in the sun. You
have to be very careful not to let UV rays eat the resin. But then,
composite construction must be viable or you wouldn't see so many Lancairs,
Cirruses, White Lightnings, Pulsars, and Eezies boring holes through the
sky.

Composite construction is labor-intensive, and that's part of the reason why
Boeing and M-D haven't migrated to it completely. Give them time.


Boeing are rapidly moving over to composite manufacturing if you look
at the press releases on the new Boeing 7E7 dreamliner project the use
of composite parts in the aircraft has risen dramatically and now it
is not just non-structural items composites are now being used to
manufacture major structural items such as tailplanes fins bulkheads
etc. The Airbus A380 is also making extensive use of composites to
minimise weight.

I believe that Boeing and Airbus both realise that the time of
composites has come they are just being cautious and implementing a
bit more with each new model.

On Sun, 30 Nov 2003, Ron Wanttaja wrote:

On the opposite side of the spectrum, I'm considering goofing around with
some homemade VGs on my Fly Baby next year. Figured I buy a batch of 1/4 -
1/2" aluminum angle and cut up a batch. Anybody have any rules of thumb
regarding size, placement, stupidity of the idea, etc.?

Better Yet, Jim Price (altitude record holding Long EZ) shows how
to make VG's from a strip of plastic panel edge moulding. It cost
about $1 at Home Depot for an eight foot length. He offers instructions
on placement, IIRC we put two on 20 degree offset, at about 20 percent
chord, every ten inches or so. Better check with Jim.
You stick them on with silicone caulking. Work great at increasing lift.

I could fly so slow that my ailerons felt too mushy, took mine off.
He can fly at 50 mph.

George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage http://bfn.org/~ca266

Ron

Some ramblings.

Tuft the section(s) and see what is happening. You can probably just
duct tape short lengths of knitting yarn to show air flow (smooth or
turbulent, etc.).

As I recall, you can then 'glue' VG's on temporarily and see the
difference in orientation of the yarn tufts.

There is probably some info that can be found on the Internet about
how the VG's work and where they should be placed to smooth out the
flow.

Might have to go to some NASA papers to get the info (your government
dollars at wok )

You might also design and make a smoke generator and blow smoke over
the section you are working with (instead of flying) to find the best
locations of VG's on your bird (and if they do you any good).

Interesting project. Lots of luck.

Big John


On Sun, 30 Nov 2003 03:37:20 GMT, Ron Wanttaja
wrote:

On Sat, 29 Nov 2003 21:27:21 -0600, Big John wrote:

There was a group (don't remember who, could have been NASA????)
sometime after the War who ran tests on the mustang wing and concluded
it was not laminar. Not sure now if this was from wind tunnel tests or
computer simulation? Also not sure what their object was, maybe just
too much time on their hands?

Then again, I've heard that it's very difficult to get true laminar flow
for *any* type of construction...at least in the real world. A bit of
dirt, a fuel cap, a small dent from a dropped tool, a few bugs splattered
on the leading edge....

On the opposite side of the spectrum, I'm considering goofing around with
some homemade VGs on my Fly Baby next year. Figured I buy a batch of 1/4 -
1/2" aluminum angle and cut up a batch. Anybody have any rules of thumb
regarding size, placement, stupidity of the idea, etc.?

Ron Wanttaja

Big John wrote:

Also in cruise you would climb several
hundred feet above your cruise altitude and in a shallow descent back
to that altitude pick up 10 mph + which the bird would hold if you
were careful and held a constant attitude. Was told (bar talk) that
was a characteristic of a laminar flow wing????

With all due respect, John, I rather think it is a characteristic of
people's ability to fool themselves. For my part, I'll believe that
Mustangs and/or Mooneys have a cruise "step" when an organization such
as NASA or CAFE documents the phenomena.

The following post by Dr. Philip Bridges of the Aerospace Engineering
Department at Mississippi State University echoes my sentiments on the
subject,

http://tinyurl.com/x48p

For the record, Dr. Bridges has recently retired from the ASE
department at Mississippi State.

Regards,

David O -- http://www.AirplaneZone.com

David O wrote:
Big John wrote:


Also in cruise you would climb several
hundred feet above your cruise altitude and in a shallow descent back
to that altitude pick up 10 mph + which the bird would hold if you
were careful and held a constant attitude. Was told (bar talk) that
was a characteristic of a laminar flow wing????


With all due respect, John, I rather think it is a characteristic of
people's ability to fool themselves. For my part, I'll believe that
Mustangs and/or Mooneys have a cruise "step" when an organization such
as NASA or CAFE documents the phenomena.

The following post by Dr. Philip Bridges of the Aerospace Engineering
Department at Mississippi State University echoes my sentiments on the
subject,

http://tinyurl.com/x48p


Correct David, there is no such thing as a step. I had not read Dr Bridges
before but fully agree with his statements.

Jerry

"David O" wrote in message
...
Big John wrote:

Also in cruise you would climb several
hundred feet above your cruise altitude and in a shallow descent back
to that altitude pick up 10 mph + which the bird would hold if you
were careful and held a constant attitude. Was told (bar talk) that
was a characteristic of a laminar flow wing????

With all due respect, John, I rather think it is a characteristic of
people's ability to fool themselves. For my part, I'll believe that
Mustangs and/or Mooneys have a cruise "step" when an organization such
as NASA or CAFE documents the phenomena.

The following post by Dr. Philip Bridges of the Aerospace Engineering
Department at Mississippi State University echoes my sentiments on the
subject,

http://tinyurl.com/x48p

For the record, Dr. Bridges has recently retired from the ASE
department at Mississippi State.

Regards,

David O -- http://www.AirplaneZone.com

WRT the "step" on powered airplanes, I wouldn't dast say. But Richard
Johnson, in his testing of sailplanes, has documented "bi-stable" polars --
measurably different drag at the same constant airspeed, depending on
whether the airspeed was approached from above or below. IIRC, he attributed
the difference to the formation (or not) of a laminar bubble at the
transition from laminar to turbulent flow. Gliders typically have lower
Reynolds numbers than power planes, so this probably doesn't apply to the
P51 and the Mooney.

Tim Ward

In properly done flight test work, the altitude is held very constant (10 ft)
for at least 5 or 10 minutes, no power changes, after you think you are
already stable. It takes this long for the speed to stabilize that last
5 kts or so. The data is taken after it is truly stable. Dead smooth air
is required. When done this way, it becomes obvious that there is
no such thing as a "step".

What we percieve as a step is a climb above the desired altitude and
then descend to the altitude before reducing power. After 5 or 10
minutes, we "fall off the step" and have to climb and descend again.
We conveniently don't count the extra climb or extra power time.

Then the real trick is to determine how much power is being produced.





In article k.net, Jerry
Springer wrote:


David O wrote:
Big John wrote:


Also in cruise you would climb several
hundred feet above your cruise altitude and in a shallow descent back
to that altitude pick up 10 mph + which the bird would hold if you
were careful and held a constant attitude. Was told (bar talk) that
was a characteristic of a laminar flow wing????


With all due respect, John, I rather think it is a characteristic of
people's ability to fool themselves. For my part, I'll believe that
Mustangs and/or Mooneys have a cruise "step" when an organization such
as NASA or CAFE documents the phenomena.

The following post by Dr. Philip Bridges of the Aerospace Engineering
Department at Mississippi State University echoes my sentiments on the
subject,

http://tinyurl.com/x48p


Correct David, there is no such thing as a step. I had not read Dr Bridges
before but fully agree with his statements.

Jerry