LSA specs

Richard,
I'll be out of town for the next 3 days. If I can't get a copy to
you before I leave tomorrow, I'll get it to you as soon as I get back.
BTW...Roncz was using a CL of 1.5

Neal


Richard Riley wrote:
On 24 Sep 2006 03:35:02 -0700, wrote:

The Roncz spreadsheets were published in Sport Aviation from February
1990 thru January 1991 ( I believe ). The one I am referring to ran in
the March 1990 issue. I'm not at the house at the moment but I'll
check when I get home and verify.


If you could email me a copy I'd like to go through and see what his
assumptions are. He may be listing a CLmax of 1.4 or so - which would
be a reasonable, conservative number. Going backwards through it,
both J.Kahn and I get a 45 knot LSA legal stall at gross, assuming a
CLmax of 1.6 and a smidge. 1.6 is ambitious but plausible.


Richard (atsign) riley *d0t* net

wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal


Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html) and
the StingSport (http://www.sting.aero/) while your at it... I bet you all
the money in my pocket they won't "compute" either, and the spreadsheet is
flawed.

--
-- ET :-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

ET wrote:
wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal


Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html) and
the StingSport (http://www.sting.aero/) while your at it... I bet you all
the money in my pocket they won't "compute" either, and the spreadsheet is
flawed.


Forget about spread sheets. The simple formula in my earlier post...

Sea Level Stall in Kts = Sq root of: [(295 x Gr Wt) Divided by (Clmax x
Wing Area)]

Multiply by 1.15 for mph.

Assume 1.6 for the Clmax. Almost all airfoils are between 1.5 and 1.7,
which gives a 1 mph or so variation up or down relative to 1.6.

....works like a charm. I used it on the Sting sport and sure enough it
comes out to 44kts just as advertised.

Use it on the Sonex and you get 45 kts. Different airfoils will
increase or decrease that by about 1kt.

John

"J.Kahn" wrote in message
...
ET wrote:
wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal


Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do
not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html)
and
the StingSport (http://www.sting.aero/) while your at it... I bet you
all
the money in my pocket they won't "compute" either, and the spreadsheet
is
flawed.


Forget about spread sheets. The simple formula in my earlier post...

Sea Level Stall in Kts = Sq root of: [(295 x Gr Wt) Divided by (Clmax x
Wing Area)]

Multiply by 1.15 for mph.

Assume 1.6 for the Clmax. Almost all airfoils are between 1.5 and 1.7,
which gives a 1 mph or so variation up or down relative to 1.6.

...works like a charm. I used it on the Sting sport and sure enough it
comes out to 44kts just as advertised.

Use it on the Sonex and you get 45 kts. Different airfoils will
increase or decrease that by about 1kt.

John

And the old graphs in the Dover Edition of Theory of Wing Sections look like
a CLmax of a little more than 1.6 can be achieved--plus whatever the
fuselage shape might ad.

Don't get me wrong. At 6'1" and 200#, I don't fit in the plane; and I
really don't like it anyway. I just don't have a problem with the specs;
and there have been plenty of designs over the years for which I do have a
problem with the specs.

Peter

Peter Dohm wrote:
"J.Kahn" wrote in message
...
ET wrote:
wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal

Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do
not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html)
and
the StingSport (http://www.sting.aero/) while your at it... I bet you
all
the money in my pocket they won't "compute" either, and the spreadsheet
is
flawed.

Forget about spread sheets. The simple formula in my earlier post...

Sea Level Stall in Kts = Sq root of: [(295 x Gr Wt) Divided by (Clmax x
Wing Area)]

Multiply by 1.15 for mph.

Assume 1.6 for the Clmax. Almost all airfoils are between 1.5 and 1.7,
which gives a 1 mph or so variation up or down relative to 1.6.

...works like a charm. I used it on the Sting sport and sure enough it
comes out to 44kts just as advertised.

Use it on the Sonex and you get 45 kts. Different airfoils will
increase or decrease that by about 1kt.

John

And the old graphs in the Dover Edition of Theory of Wing Sections look like
a CLmax of a little more than 1.6 can be achieved--plus whatever the
fuselage shape might ad.

Don't get me wrong. At 6'1" and 200#, I don't fit in the plane; and I
really don't like it anyway. I just don't have a problem with the specs;
and there have been plenty of designs over the years for which I do have a
problem with the specs.

Peter



Yeah I'm 6' and 200 and the Sonex was a very tight fit. At Osh I
commented on the lack of head room for a long torso type like me and he
said "sit in the middle". Yeah right.

The good news is that I think we're zeroing in on the problem. I'll
compare the formulas with the Roncz spreadsheet and the formula John
suggests and see where the difference is. You're right in that these
competent designers are coming up with figures that all suggest the
stall speeds can be achieved with a smaller wing, but I wouldn't go so
far as to say they're any better than John Roncz. I believe he is
responsible for most of Rutan's airfoils which have been proven to do
pretty much what they said they'd do. I'll report back what I find.
Thanks for the good discussion.

Neal

ET wrote:
wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal


Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html) and
the StingSport (http://www.sting.aero/) while your at it... I bet you all
the money in my pocket they won't "compute" either, and the spreadsheet is
flawed.

--
-- ET :-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

I believe that John Roncz is also responsible for the airfoil on the RV-9
and RV-9A, which also have a low stall speed.

Peter

wrote in message
ups.com...
The good news is that I think we're zeroing in on the problem. I'll
compare the formulas with the Roncz spreadsheet and the formula John
suggests and see where the difference is. You're right in that these
competent designers are coming up with figures that all suggest the
stall speeds can be achieved with a smaller wing, but I wouldn't go so
far as to say they're any better than John Roncz. I believe he is
responsible for most of Rutan's airfoils which have been proven to do
pretty much what they said they'd do. I'll report back what I find.
Thanks for the good discussion.

Neal

ET wrote:
wrote in
ups.com:

John,
I hear what you're saying, but with all that's been said here, and
investigated via spreadsheets, etc., I still don't think the Sonex can
stall near the LSA requirement at max gross wt. and no flaps which
means it is not LSA qualified. And just for grins, I looked up the
figures for the CT Flight Design ( which is a popular seller ) and
guess what. IT doesn't meet the LSA criteria. And I also looked up
the new Vans RV-12 "LSA" and you guessed it....IT doesn't meet the
stall speed criteria ( at least not on paper...I don't think it has
flown yet.) So I'm convinced that something is amiss. I'll keep
researching.

Neal


Well then guess what, the spreadsheet is what's flawed. I guarantee CT
(the best selling LSA by far) and Vans, and the Pete Buck know what they
are doing far better then the developer of your spreadsheet...

3 real world examples of planes that clearly meet the LSA specs but do
not
meet it "on paper".

Do it for the SportStar (http://www.evektoramerica.com/sportstar.html)
and
the StingSport (http://www.sting.aero/) while your at it... I bet you
all
the money in my pocket they won't "compute" either, and the spreadsheet
is
flawed.

--
-- ET :-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

wrote in
ups.com:

The good news is that I think we're zeroing in on the problem. I'll
compare the formulas with the Roncz spreadsheet and the formula John
suggests and see where the difference is. You're right in that these
competent designers are coming up with figures that all suggest the
stall speeds can be achieved with a smaller wing, but I wouldn't go so
far as to say they're any better than John Roncz. I believe he is
responsible for most of Rutan's airfoils which have been proven to do
pretty much what they said they'd do. I'll report back what I find.
Thanks for the good discussion.

Neal

OK, well not that those folks are "better then" Roncz, but that his formula
is obviously flawed when it comes to these smaller aircraft, or perhaps it
is being mis-applied here?



--
-- ET :-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

wrote:
Could someone clarify something for me concerning LSA's. The websites
that have the detailed LSA aircraft limitations listed say that the
plane must have a maximum stalling speed of 51 mph at the maximum gross
takeoff weight WITHOUT the use of high lift devices.

I plugged the numbers for a Sonex into the John Roncz spreadsheets. (
Max Gross TOW of 1150 lbs, stall of 46 mph ) and it reports that I need
a wing area of 180 sq. feet. The Sonex only has 98 square feet of
wing. What am I missing?

Thanks
Neal

There's something very wrong with your spreadsheet. A quick sanity
check shows that a Cessna 172 doesn't have 180 sq feet of wing (it is
174 sq ft) and it carries four people, baggage, 320 pounds of fuel and
still manages a stall speed of 51 knots (no flaps, "R" model), only a
little higher than LSA requirements.

I have flown most all of the S-LSA aircraft and a lot of experimetals
that are LSA compliant. I am fairly confident that their figures are
not exaggerated.

Rick Pellicciotti
LightSportFlying.com

Rick,
I really wish I could claim it is my spreadsheet. I've been
referring to the spreadsheets written for Sport Aviation by Jonh Roncz.
Upon looking at his spreadsheets closer, I remembered that he had TWO
of them that calculated stall speeds and they had different results for
stall speeds. He gave an explanation of why there are 2 different stall
speeds but I'll have to go back to the magazines and look it up to find
out exactly why. I think this may be the answer I've been searching
for. I'll try to do this tonite and reply. Thanks

Neal

rpellicciotti wrote:
wrote:
Could someone clarify something for me concerning LSA's. The websites
that have the detailed LSA aircraft limitations listed say that the
plane must have a maximum stalling speed of 51 mph at the maximum gross
takeoff weight WITHOUT the use of high lift devices.

I plugged the numbers for a Sonex into the John Roncz spreadsheets. (
Max Gross TOW of 1150 lbs, stall of 46 mph ) and it reports that I need
a wing area of 180 sq. feet. The Sonex only has 98 square feet of
wing. What am I missing?

Thanks
Neal

There's something very wrong with your spreadsheet. A quick sanity
check shows that a Cessna 172 doesn't have 180 sq feet of wing (it is
174 sq ft) and it carries four people, baggage, 320 pounds of fuel and
still manages a stall speed of 51 knots (no flaps, "R" model), only a
little higher than LSA requirements.

I have flown most all of the S-LSA aircraft and a lot of experimetals
that are LSA compliant. I am fairly confident that their figures are
not exaggerated.

Rick Pellicciotti
LightSportFlying.com