LSA specs

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

On 23 Sep 2006 08:30:21 -0700, 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?

Eighty-two square feet of wing area?

Ron "Go ahead, try a harder one" Wanttaja

wrote in news:1159025421.579979.9980
@i42g2000cwa.googlegroups.com:

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


Take a real good look at the profile of the Sonex airframe.... looks
suspiciously like an airfoil doesnt it???

--
-- 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 message
ps.com...
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

I *think* high lift devices are considered to be Fowler flaps, slats, slots,
etc. Everything I can find on the internet indicates that conventional
hinged flaps are allowed on LSA's.

If you look at something with a similar planform, more weight and more wing
area (an RV-6), you'll find that the CAFE foundation measured a flaps down
stall speed of 52 mph for an RV-6a, which is an indicator that a Sonex could
meet the 51 mph regulation.

http://cafefoundation.org/v2/pdf/RV-...inal%20APR.pdf

KB

Any flap is considered a high lift device. An LSA can have flaps, but the stall speed clean is what is the determining
factor for the 45 knot (52MPH) limit. Seems that the powers that be do not want to require pilots to operate any but the
most basic flight and engine controls. Even a LSA 'amphib' with wheels on the floats cannot change the configuration
while in flight - the wheels need to be fixed either extended (for land takeoff and landing) or retracted for water
takeoff and 'landing'.


"Kyle Boatright" wrote in message . ..
:
: wrote in message
: ps.com...
: 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
:
: I *think* high lift devices are considered to be Fowler flaps, slats, slots,
: etc. Everything I can find on the internet indicates that conventional
: hinged flaps are allowed on LSA's.
:
: If you look at something with a similar planform, more weight and more wing
: area (an RV-6), you'll find that the CAFE foundation measured a flaps down
: stall speed of 52 mph for an RV-6a, which is an indicator that a Sonex could
: meet the 51 mph regulation.
:
: http://cafefoundation.org/v2/pdf/RV-...inal%20APR.pdf
:
: KB
:
:

In a previous article, ".Blueskies." said:
most basic flight and engine controls. Even a LSA 'amphib' with wheels
on the floats cannot change the configuration
while in flight - the wheels need to be fixed either extended (for land
takeoff and landing) or retracted for water
takeoff and 'landing'.

The makers of one flying-boat style LSA (memory says Mermaid or Merlin or
something like that) have gotten a waiver that allows Light Sport pilots
to get special training to operate the gear.

--
Paul Tomblin http://xcski.com/blogs/pt/
I got accused of being humorless last night. I'm considering quoting
Lieutenant Commander Data: "Perhaps the joke was not funny."
-- Alan Rosenthal

("Kyle Boatright" wrote)
If you look at something with a similar planform, more weight and more
wing area (an RV-6), you'll find that the CAFE foundation measured a flaps
down stall speed of 52 mph for an RV-6a, which is an indicator that a
Sonex could meet the 51 mph regulation.

http://cafefoundation.org/v2/pdf/RV-...inal%20APR.pdf


Interesting site!

http://cafefoundation.org/v2/research_aprs.php
"Aircraft Performance Reports"

(From CAFE Home page)
For over 25 years the aviation enthusiasts at the (C)omparative (A)ircraft
(F)light (E)fficiency Foundation have been carefully measuring personal
aircraft performance with innovations in flight testing. Their passion for
this stems from the thrill of working with state-of-the-art aircraft and the
geniuses who create them.


Montblack

Actually, the CAFE numbers come out a little better than what Van
states as the performance figures for the RV-6. And the stall speeds
that Van posts are pretty much what J. Roncz predicts in his
spreadsheets, even though Van's are a bit better. But then again Van's
planes may be operating at a slightly higher CL than what Roncz uses.
Which leads me to believe that the spreadsheets are quite accurate.

This is why I'm having a hard time believing that the Sonex aircraft
meet the LSA rules as written. Even at the lightest version of their
aircraft ( Jabiru 2200 power and flown solo and no fuel ) the plane
would have a hard time meeting the stall requirements of LSA which
require max gross wt. figures with a 51 mph stall speed.

And my intention is to fully understand the LSA rules, not "down" the
Sonex aircraft or the people behind it. I believe the Sonex and its
people to be top notch, as do many others, evidenced by how many are
flying and continue to be built. They are reasonally priced,
economical to operate and good "all around" performers for their
power. And from what I have seen, several of the other "popular" LSA's
would have a hard time meeting the LSA specs. as I see them written.

Neal

Kyle Boatright wrote:
wrote in message
ps.com...
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

I *think* high lift devices are considered to be Fowler flaps, slats, slots,
etc. Everything I can find on the internet indicates that conventional
hinged flaps are allowed on LSA's.

If you look at something with a similar planform, more weight and more wing
area (an RV-6), you'll find that the CAFE foundation measured a flaps down
stall speed of 52 mph for an RV-6a, which is an indicator that a Sonex could
meet the 51 mph regulation.

http://cafefoundation.org/v2/pdf/RV-...inal%20APR.pdf

KB

wrote in
ups.com:

Actually, the CAFE numbers come out a little better than what Van
states as the performance figures for the RV-6. And the stall speeds
that Van posts are pretty much what J. Roncz predicts in his
spreadsheets, even though Van's are a bit better. But then again
Van's planes may be operating at a slightly higher CL than what Roncz
uses. Which leads me to believe that the spreadsheets are quite
accurate.

This is why I'm having a hard time believing that the Sonex aircraft
meet the LSA rules as written. Even at the lightest version of their
aircraft ( Jabiru 2200 power and flown solo and no fuel ) the plane
would have a hard time meeting the stall requirements of LSA which
require max gross wt. figures with a 51 mph stall speed.

And my intention is to fully understand the LSA rules, not "down" the
Sonex aircraft or the people behind it. I believe the Sonex and its
people to be top notch, as do many others, evidenced by how many are
flying and continue to be built. They are reasonally priced,
economical to operate and good "all around" performers for their
power. And from what I have seen, several of the other "popular"
LSA's would have a hard time meeting the LSA specs. as I see them
written.

Neal



Which part of my post that indicated the fuselage of the Sonex is a
lifting body confused you??? Steve Wittman is said to have won a bet or
two with the same issue on the Tailwind. I have not done it, but plug
the same numbers in for the Tailwind and see what pops out.

--
-- 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 in message
...
wrote in
ups.com:

snip

Which part of my post that indicated the fuselage of the Sonex is a
lifting body confused you??? Steve Wittman is said to have won a bet or
two with the same issue on the Tailwind. I have not done it, but plug
the same numbers in for the Tailwind and see what pops out.

--
-- ET :-)

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

Can you find a credible test of the Tailwind's stall speed on the web? I've
looked for one, but without success. The CAFE report in the "members"
section of the EAA site doesn't show the stall speed, although the text
discusses stall speed testing. I seem to remember that Tailwinds with the
stock pitot/static system have an inaccurate ASI at low speeds, showing much
lower airspeed than actual.

A buddy who owned a Tailwind described it as a fast airplane, but with
"mean" low speed characteristics.

I don't buy into the theory that Tailwinds or Soni (?) gain much lift from
the fuselage. The aspect ratio of a fuselage is too small to generate a lot
of lift.

KB