flying flea aerodynamics question

mignet's flea had an aerodynamic problem due to an unpredicted slot
effect.

this is from a british museum web site....
"Following a series of fatal accidents involving this type the French
authorities banned its use in 1936 and wind tunnel tests revealed an
aerodynamic flaw that could result in an uncontrollable and ever
steeper dive. The Air Ministry subsequently issued a ban in the summer
of 1937 and GAEEH was dismantled and stored in the owner's garage."

the wind tunnel tests referred to were in the RAE tunnel at
farnborough and made the flea the first full size aircraft ever tested
in the tunnel (because it was small enough to fit).

the result of the work done in farnborough actually saw a number of
mods to the flea that actually fixed the problem.

has anyone ever seen an aerodynamics report from the wind tunnel
testing. I am presuming that there would have been a formal report
written up and while the nasa web search engine gives us access to the
naca aerodynamics work, I've never encountered similar from the
british.

does anyone have a link to a report of the 1936/7 flying flea
aerodynamics investigations?
I'd sure appreciate one.

Stealth Pilot

Stealth Pilot schreef:

has anyone ever seen an aerodynamics report from the wind tunnel
testing. I am presuming that there would have been a formal report
written up and while the nasa web search engine gives us access to the
naca aerodynamics work, I've never encountered similar from the
british.


Searching the web I found the 1936 tests mentioned he
http://pou.guide.free.fr/construire/..._direction.htm
which also mentions one Frank Easton, apparently a US-an advocate of the
Mignet designs.
No mention of report or analysis, though.

in yahoo groups there's at least one flying flea group. Pat

On Fri, 11 Sep 2009 15:43:55 +0000, jan olieslagers
wrote:

Stealth Pilot schreef:

has anyone ever seen an aerodynamics report from the wind tunnel
testing. I am presuming that there would have been a formal report
written up and while the nasa web search engine gives us access to the
naca aerodynamics work, I've never encountered similar from the
british.


Searching the web I found the 1936 tests mentioned he
http://pou.guide.free.fr/construire/..._direction.htm
which also mentions one Frank Easton, apparently a US-an advocate of the
Mignet designs.
No mention of report or analysis, though.

I've had a look through that site.
what prompted this was a book published in england.

Arthur Ord-Hume has published a neat book reprinting the Flying Flea,
'how to build one' articles in practical mechanics and recounts the
english experience related to the flea.
he also has the articles on building the Luton Minor which was
published as a safer aircraft to build.

quite an interesting book to read and has just been published.
"The first Home-built aeroplanes" Arthur W.J.G. Ord-Hume.
Pounds Sterling 9.95
published by stenlake (www.stenlake.co.uk)
isbn 9781-84033-449-4
I got mine through a rellie who got it through amazon for me.

Stealth Pilot

"Stealth Pilot" wrote

Bob I actually found it.
I stopped hunting for the report itself and went poking around the RAE
Farnborough web sites.

I have in progress a request to scan to PDF both report copies.
I have to pay for this service but I've been after the original report
now for well over 10 years so I dont mind too much.

I have suggested that they follow the NASA example :-)

sometimes posting a request here clears the mind and allows for the
answer to push through :-)

Interesting. I have to admit that I am intrigued by what they had to do to
tame such an unconventional wing layout.

Would you be kind enough to post them to alt.binaries.pictures.aviation
?

I know that group is for pictures, but they say a picture is worth a
thousand words. Perhaps a thousand words is worth a picture, too. g
--
Jim in NC

"Stealth Pilot" wrote

I've had a look through that site.
what prompted this was a book published in england.

Arthur Ord-Hume has published a neat book reprinting the Flying Flea,
'how to build one' articles in practical mechanics and recounts the
english experience related to the flea.
he also has the articles on building the Luton Minor which was
published as a safer aircraft to build.

quite an interesting book to read and has just been published.
"The first Home-built aeroplanes" Arthur W.J.

I am wondering about your interest in this plane. Are you planning to
build
it, or just interesting information to put into your brain?

I understand about new information for the brain, and seem to have run
across an opportunity like that lately... Thanks again, for that. g
--
Jim in NC

Morgans wrote:

Interesting. I have to admit that I am intrigued by what they had to
do to tame such an unconventional wing layout.

IIRC, the problem was due to the close spacing of the two tandem wings.
The front wing is higher than the rear one, and pivots for pitch control.

On the original Flea, there was a longitudinal overlap of the front and
back wings...the trailing edge of the front wing is aft of the leading
edge of the back one.

http://collections.nasm.si.edu/media...610020000a.JPG

When the pilot pulled back on the stick, the gap between the wings would
decrease. With the closely-spaced wings of the original design, this
would start "pinching off" the gap.

With Mignet's original low-power, slow speed concept, it didn't make
much difference. But as people starting putting flying them faster and
more aggressively, the air squeezing through the gap would
accelerate...increasing the airflow over the top of the aft wing, which
would increase its lift. The plane tended to pitch down, so the pilot
would pull back on the stick, which would accelerate the air MORE, cause
MORE pitch-down, etc.

The basic cure was an increased separation between the wings...the top
wing was moved higher, and/or the aft wing was moved back further.

http://members.fortunecity.com/gvanr...ilt/pdc-10.jpg

http://www.davidandivy.co.uk/images/ac5_flying_flea.jpg

Ron Wanttaja

On Sat, 12 Sep 2009 06:34:06 -0700, Ron Wanttaja
wrote:

Morgans wrote:

Interesting. I have to admit that I am intrigued by what they had to
do to tame such an unconventional wing layout.

IIRC, the problem was due to the close spacing of the two tandem wings.
The front wing is higher than the rear one, and pivots for pitch control.

On the original Flea, there was a longitudinal overlap of the front and
back wings...the trailing edge of the front wing is aft of the leading
edge of the back one.

http://collections.nasm.si.edu/media...610020000a.JPG

When the pilot pulled back on the stick, the gap between the wings would
decrease. With the closely-spaced wings of the original design, this
would start "pinching off" the gap.

With Mignet's original low-power, slow speed concept, it didn't make
much difference. But as people starting putting flying them faster and
more aggressively, the air squeezing through the gap would
accelerate...increasing the airflow over the top of the aft wing, which
would increase its lift. The plane tended to pitch down, so the pilot
would pull back on the stick, which would accelerate the air MORE, cause
MORE pitch-down, etc.

The basic cure was an increased separation between the wings...the top
wing was moved higher, and/or the aft wing was moved back further.

http://members.fortunecity.com/gvanr...ilt/pdc-10.jpg

http://www.davidandivy.co.uk/images/ac5_flying_flea.jpg

Ron Wanttaja

there are a few other things Ron.
the aerofoil(s) was changed.
the wing separation was increased.
the wing control was made a pushrod.
an elevator was incorporated in the rear wing.
the spar position was moved.

it will be interesting to read the report firsthand as a matter of
historical accuracy.
Stealth Pilot

On Sat, 12 Sep 2009 09:20:28 -0400, "Morgans"
wrote:


"Stealth Pilot" wrote

I've had a look through that site.
what prompted this was a book published in england.

Arthur Ord-Hume has published a neat book reprinting the Flying Flea,
'how to build one' articles in practical mechanics and recounts the
english experience related to the flea.
he also has the articles on building the Luton Minor which was
published as a safer aircraft to build.

quite an interesting book to read and has just been published.
"The first Home-built aeroplanes" Arthur W.J.

I am wondering about your interest in this plane. Are you planning to
build
it, or just interesting information to put into your brain?

I understand about new information for the brain, and seem to have run
across an opportunity like that lately... Thanks again, for that. g

I'm interested in the history of homebuilding and home built designs,
and understanding the engineering.
as a kid in highschool a little book on homebuilts that featured,
among others, a blue cassutt racer and a sectioned view of a flying
flea first piqued my interest in aviation.

my own building efforts I have decided will resurect some of the
classic wooden homebuilt aircraft. current target is the Turbulent.
a little jodel d9 might be next.

if anyone was to build a flea I think they'd be taking their life in
their hands flying it on anything other than a windless balmy spring
or autumn day. every other aeroplane has ailerons for a bloody good
reason. when I read of all the condemning of the design it flagged
something in my head beside the sectioned image of the flea.
years later I read the english translation of 'the flying flea- how to
build and fly it' by mignet and I was surprised to find that it had a
competent structure. mignet's hm14 is structurally ok imho.
the current search is just to read the original source document of the
aerodynamic investigations.

one thing I discovered from the library list was an online article in
the Flight magazine archives. 11th april 1935 pages 385 and 386 is an
interesting description with drawings of the Aubier et Dunne 17hp two
cylinder geared engine built in france for the Flea. an interesting
little engine.
http://www.flightglobal.com/pdfarchi...0-%200806.html
the link points to the second page.
Stealth Pilot

On Mon, 14 Sep 2009 20:57:29 -0400, "Peter Dohm"
wrote:


The Vw is too heavy I think. Mignet and the french used the 17hp
Aubier et Dunne engine quite successfully. I havent found a weight for
the Aubier but the Scott Squirrel at 16hp weighed 85lb so I'm assuming
the Aubier would be similar. that puts the vw at about a third too
heavy and would lead to the insidious weight spiral.(heavier engine
needing a stronger structure, needing more power and bigger wing etc)

To the best of my recollection, the little litterature that I saw for a
single seat Flea described and showed a Harley-Davidson V-twin engine with a
belt reduction drive. I subsequently saw some passing mention of 2 seat
varients with fully enclosed cabins and up to 125 horsepower aircraft
engines.

Peter

see what I wrote for bob.
they are different models from the HM14.
(all chinese look the same too)

Stealth Pilot