Flaperons

[Lou Parker]

I just don't get it. Can anyone successfully explain how flaperons
work? Are they better or worse than seperate flaps? What are the pro's
and con's? It seems to me if one fails you have no recovery.
Lou

[Bill Daniels]

"Lou Parker" > wrote in message
om...
> I just don't get it. Can anyone successfully explain how flaperons
> work? Are they better or worse than seperate flaps? What are the pro's
> and con's? It seems to me if one fails you have no recovery.
> Lou

At least in sailplanes, they work very well. My Nimbus 2C droops the
ailerons with the flaps but at a lesser rate which introduces a large
effective wing twist at low speeds.

The upside of flaperons is that the whole span is flapped which improves low
speed performance and the total aileron area is larger which improves roll
authority.

The down side is when you need a lot of aileron at a time when full flaps
are deployed they the roll response heavy and sluggish. The solution is to
hold off on full flaps until you are on short final.

Bill Daniels

[Larry]

"Lou Parker" > wrote in message
om...
> I just don't get it. Can anyone successfully explain how flaperons
> work? Are they better or worse than seperate flaps? What are the pro's
> and con's? It seems to me if one fails you have no recovery.
> Lou

My experience is on the A-6 (series) military aircraft that has a Flaperon
System. As the stick is moved Right, the Right Flaperon gradually comes up,
killing some of the lift on the right wing, causes a loss of lift, the wing
drops, and the A/C banks Right. These surfaces are what you would think a
'spoiler' would look like and operate much like an Aileron.

A completely separate system causes both Flaperons to 'popup' on touchdown
while landing 'shorebased'. This kills the lift (as soon as the wheels
touchdown) and allows the aircraft to quickly 'settle into the gear' so the
Anti-Skid system can work effectively, thus slowing the A/C safely.

An added note: the Flaperons are really 'misnamed' because (at least in the
case of the A-6) they have nothing to do with Flaps. The A-6 (and many other
Naval Aircraft) have Flaps (on the trailing edge) and Slats (on the leading
edge).

Hope this helps.

Larry
AECS (AW/SW/MTS)
USN 'Retired'
20 years if gettin 'em off the pointy end
AND safely home again!

[Wayne Paul]

"Larry" > wrote in message
...
>
> An added note: the Flaperons are really 'misnamed' because (at least in
the
> case of the A-6) they have nothing to do with Flaps. The A-6 (and many
other
> Naval Aircraft) have Flaps (on the trailing edge) and Slats (on the
leading
> edge).
>
> Hope this helps.
>
> Larry
> AECS (AW/SW/MTS)
> USN 'Retired'
> 20 years if gettin 'em off the pointy end
> AND safely home again!
>

Larry,

You are correct. The A-6 Flaperons are indeed misnamed. In reality they
are spoilers very similar in design to the glide slope control spoilers used
on Schweizer sailplanes.

Wayne
http://www.soaridaho.com/Schreder

Retired A-6 Bombardier

[Dan Nafe]

In article <_q4ld.24439$V41.4860@attbi_s52>,
"Bill Daniels" > wrote:


[snip]
> The down side is when you need a lot of aileron at a time when full flaps
> are deployed they the roll response heavy and sluggish. The solution is to
> hold off on full flaps until you are on short final.


always a good idea

[QDurham]

>The solution is to
>> hold off on full flaps until you are on short final.
>
>
>always a good idea

Of course if you are really good, and are flying a real airplane, to hell with
the flaps. Slip it in. Can always "unslip," you know, but "unflapping" is
looking for trouble.

Quent

[Bill Daniels]

"QDurham" > wrote in message
...
> >The solution is to
> >> hold off on full flaps until you are on short final.
> >
> >
> >always a good idea
>
> Of course if you are really good, and are flying a real airplane, to hell
with
> the flaps. Slip it in. Can always "unslip," you know, but "unflapping" is
> looking for trouble.
>
> Quent

Actually, the dive brakes on my sailplane will convert the 50:1 glider (30:1
with approach flaps) to 5:1 and back in the blink of an eye. Slips aren't
needed or, for that matter, very effective.

Bill Daniels

[Ron Natalie]

QDurham wrote:
>>The solution is to
>>
>>>hold off on full flaps until you are on short final.
>>
>>
>>always a good idea
>
>
> Of course if you are really good, and are flying a real airplane, to hell with
> the flaps. Slip it in. Can always "unslip," you know, but "unflapping" is
> looking for trouble.
>
How effective a slip is depends on what how much rudder you have and how big
the sides of your aircraft is. A lot of go fast planes and high performance
gliders don't get too much drag out of a slip.

[Robertmudd1u]

>I just don't get it. Can anyone successfully explain how flaperons
>work? Are they better or worse than seperate flaps? What are the pro's
>and con's? It seems to me if one fails you have no recovery.
> Lou

Lou,

I have flown several gliders with flaperons but no airplanes so equipped.
The glider I have the most time in is the Apis 13, this has a wing span of 13
meters about 42.5 ft.

The roll rate is great because the entire trailing edge acts as a aileron, and
the flaps really work well because they are the full span of the trailing edge,
so independently I get very good results for these controls.

When thermaling with a notch or two of flap I see little if any reduction in
roll rate, Yes the aileron that is going up does not go as far up as if the
flaps were at the zero setting, but it does not seem to matter.

Bill Daniels mentioned his glider, which has a 20 meter wing, that is quite
heavy. It has, (for a glider) a relatively slow roll rate anyway. The Apis is
much lighter and nimble and so roll control with full flaps is just fine, in
fact they make the glider a real blast to fly.

The mechanism is quite simple. Each flaperon is driven from its root end by a
torque rod, the flaperons are center hinged. The flaperons on the Apis are of
carbon fiber so torque loads are easily handled.

If you are near a glider club look at a DG brand glider, they use flaperons a
lot in their gliders.

I do not know if they are more effective than separate flaps and ailerons but
they do cover a larger part of the wing's trailing edge so in some or maybe
even most circumstances I think they maybe more effective.

So far I have had no reason to complain.

Robert Mudd

[Larry]

"Wayne Paul" > wrote in message
...
>
> "Larry" > wrote in message
> ...
> >
> > An added note: the Flaperons are really 'misnamed' because (at least in
> the
> > case of the A-6) they have nothing to do with Flaps. The A-6 (and many
> other
> > Naval Aircraft) have Flaps (on the trailing edge) and Slats (on the
> leading
> > edge).
> >
> > Hope this helps.
> >
> > Larry
> > AECS (AW/SW/MTS)
> > USN 'Retired'
> > 20 years if gettin 'em off the pointy end
> > AND safely home again!
> >
>
> Larry,
>
> You are correct. The A-6 Flaperons are indeed misnamed. In reality they
> are spoilers very similar in design to the glide slope control spoilers
used
> on Schweizer sailplanes.
>
> Wayne
> http://www.soaridaho.com/Schreder
>
> Retired A-6 Bombardier


I can recall spending many a late night out there re-rigging the control
surfaces on the Prowler (Navy EA-6B) when I worked in Quality Assurance. The
Airframes guys would make an adjustment and we'd have to witness the
'throws' to ensure all was within specs. That dam Hydraulic Genny was
screaming and the hydraulics were whining- It's no wonder I lost most of my
hearing.

All that 'so we could 'make the flight schedule'. Now it's somebody else's
turn to 'wrench on those jets'.


Larry
AECS (AW/SW/MTS)
USN 'Retired'
20 years if gettin 'em off the pointy end
AND safely home again!
















>
>

[Bill Daniels]

"Robertmudd1u" > wrote in message
...
> >I just don't get it. Can anyone successfully explain how flaperons
> >work? Are they better or worse than seperate flaps? What are the pro's
> >and con's? It seems to me if one fails you have no recovery.
> > Lou
>
> Lou,
>
> I have flown several gliders with flaperons but no airplanes so equipped.
> The glider I have the most time in is the Apis 13, this has a wing span of
13
> meters about 42.5 ft.
>
> The roll rate is great because the entire trailing edge acts as a aileron,
and
> the flaps really work well because they are the full span of the trailing
edge,
> so independently I get very good results for these controls.
>
> When thermaling with a notch or two of flap I see little if any reduction
in
> roll rate, Yes the aileron that is going up does not go as far up as if
the
> flaps were at the zero setting, but it does not seem to matter.
>
> Bill Daniels mentioned his glider, which has a 20 meter wing, that is
quite
> heavy. It has, (for a glider) a relatively slow roll rate anyway. The Apis
is
> much lighter and nimble and so roll control with full flaps is just fine,
in
> fact they make the glider a real blast to fly.
>
> The mechanism is quite simple. Each flaperon is driven from its root end
by a
> torque rod, the flaperons are center hinged. The flaperons on the Apis are
of
> carbon fiber so torque loads are easily handled.
>
> If you are near a glider club look at a DG brand glider, they use
flaperons a
> lot in their gliders.
>
> I do not know if they are more effective than separate flaps and ailerons
but
> they do cover a larger part of the wing's trailing edge so in some or
maybe
> even most circumstances I think they maybe more effective.
>
> So far I have had no reason to complain.
>
> Robert Mudd
>

Yup, and that 20 meter wing gets a lot heavier when I put 75 gallons of
water in it.
(H2O - the go-fast juice).

Bill Daniels

Bill Daniels

[BRO]

Never mind mate, I got it, and had a laugh..

Brett.

"QDurham" > wrote in message
...
> >The solution is to
>>> hold off on full flaps until you are on short final.
>>
>>
>>always a good idea
>
> Of course if you are really good, and are flying a real airplane, to hell
> with
> the flaps. Slip it in. Can always "unslip," you know, but "unflapping" is
> looking for trouble.
>
> Quent

[Whunicut]

>I can recall spending many a late night out there re-rigging the control
>surfaces on the Prowler (Navy EA-6B) when I worked in Quality Assurance. The
>Airframes guys would make an adjustment and we'd have to witness the
>'throws' to ensure all was within specs. That dam Hydraulic Genny was
>screaming and the hydraulics were whining- It's no wonder I lost most of my
>hearing.
>
>All that 'so we could 'make the flight schedule'. Now it's somebody else's
>turn to 'wrench on those jets'.
>
>
>Larry
>AECS (AW/SW/MTS)
>USN 'Retired'
>20 years if gettin 'em off the pointy end
>AND safely home again!
>
You QA guys get that "partial ejection" incident in an A-6 figgered out? :-))
Warren,

[Wayne Paul]

Warren,

Here is the complete story:
http://www.gallagher.com/ejection_seat/

My person recollection of the story was a bit fuzzy.

Wayne
(A-6 Bombardier that has logged more takeoffs then landings.)

"Whunicut" > wrote in message
...
> >I can recall spending many a late night out there re-rigging the control
> >surfaces on the Prowler (Navy EA-6B) when I worked in Quality Assurance.
The
> >Airframes guys would make an adjustment and we'd have to witness the
> >'throws' to ensure all was within specs. That dam Hydraulic Genny was
> >screaming and the hydraulics were whining- It's no wonder I lost most of
my
> >hearing.
> >
> >All that 'so we could 'make the flight schedule'. Now it's somebody
else's
> >turn to 'wrench on those jets'.
> >
> >
> >Larry
> >AECS (AW/SW/MTS)
> >USN 'Retired'
> >20 years if gettin 'em off the pointy end
> >AND safely home again!
> >
> You QA guys get that "partial ejection" incident in an A-6 figgered out?
:-))
> Warren,
>
>

[Nils Rostedt]

"Lou Parker" > wrote in message
om...
> I just don't get it. Can anyone successfully explain how flaperons
> work? Are they better or worse than seperate flaps? What are the pro's
> and con's? It seems to me if one fails you have no recovery.
> Lou

I'll try ;-)

Flaperons are control surfaces that look like full span ailerons. They work
both as ailerons (i.e. move in opposite directions when the stick is moved)
and as flaps (i.e. move in the same direction when the flap handle is
moved).
There is a mechanical "mixer" device connected to the stick and flap handle
that transmits the movement to the control surfaces so that they move as
described above.

The advantage, in theory, is that you can have effective, full span ailerons
at the same time with effective full span flaps that can bring the stall
speed down. To get the same effect with conventional control surfaces, the
flaps need to be of more exotic design such as the split or Fowler type
flaps.

The main disadvantage is that when the flaps are in use you get an increased
adverse yaw moment, which may make steering more difficult during approach.
Also, as the flap deflection angle is limited compared to conventional
flaps, the drag increase (speedbrake effect) is smaller. This means the
airplane floats longer in ground effect on landing, making short field
landings more difficult.

A pilot friend had a Rans S-10 Sakota with flaperons. He told me he rarely
used the flap function, preferring to sideslip on approach.

The French DynAero MCR-01 high performance plane (Ban-Bi in the US) was
originally designed (in the microlight/UL version) with double slotted
flaperons to comply with the stall speed requirement of 35 knots (65 km/h)
even with a very small wing area. After a few years, they were able to tweak
the wing design to fulfil the stall speed requirement also with a
conventional arrangement with ailerons and double slotted flaps, and this is
the current configuration.

A number of airplanes (gliders in particular) have ailerons which are
connected with the flaps and move with them. In these planes, the main idea
is to be able to reduce drag with negative deflection of the ailerons
together with the flaps. But I'd hesitate to call them flaperons in this
case, where the wing also has separate flaps.

Please correct me if I got something wrong, my practical exeprience of
flaperons is limited to radio controlled model airplanes ;-)
// N

[Whunicut]

>Here is the complete story:
>http://www.gallagher.com/ejection_seat/
>
>My person recollection of the story was a bit fuzzy.
>

Now that had to be one more wild ride! I would have thought he was dead too but
everything broke just right for him. Kudos for the great job by the pilot!
Thanks Wayne.
Warren

[[email protected]]

The Mosquito (glider) has an unusual arrangement, not flaperons, but quite
related.
The ailerons and flaps move together when commanded by one lever. That's
quite common on 15meter ships. The ailerons move independently of the flaps
for aileron control. When you pull a different lever, for airbrake, the
flaps deflect
downward and a spoiler comes up (the spoiler is hinged at it's trailing edge
and
actually pushes the flap down) but the ailerons do not move. Then you can
move
the ailerons up and down in unison with the lever that I first mentioned
while at
the same time can be moved like normal ailerons. The ailerons have
differential
as well, more up than down. It is quite a system. The drag range is very
large.
The stall speed is hardly changed at all between flaps up and down.
Typically
I will takeoff with the flaps and ailerons full up. It makes a distinct
difference in
roll authority. After landing the first order of business is to get the
ailerons up
for this better aileron authority. By modulating the flaps/speed brake you
can
control your landing roll considerably (on hard surface). I must note - just
because the stall speed doesn't change much with speed brakes it doesn't
mean that the lift isn't changed much. The way we do stalls is not measuring
your descent rate, it is measuring the speed at which you lose the ability
to
control the aircraft.


Nils Rostedt wrote in message >...
>"Lou Parker" > wrote in message
om...
>> I just don't get it. Can anyone successfully explain how flaperons
>> work? Are they better or worse than seperate flaps? What are the pro's
>> and con's? It seems to me if one fails you have no recovery.
>> Lou
>
>I'll try ;-)
>
>Flaperons are control surfaces that look like full span ailerons. They work
>both as ailerons (i.e. move in opposite directions when the stick is moved)
>and as flaps (i.e. move in the same direction when the flap handle is
>moved).
>There is a mechanical "mixer" device connected to the stick and flap handle
>that transmits the movement to the control surfaces so that they move as
>described above.
>
>The advantage, in theory, is that you can have effective, full span
ailerons
>at the same time with effective full span flaps that can bring the stall
>speed down. To get the same effect with conventional control surfaces, the
>flaps need to be of more exotic design such as the split or Fowler type
>flaps.
>
>The main disadvantage is that when the flaps are in use you get an
increased
>adverse yaw moment, which may make steering more difficult during approach.
>Also, as the flap deflection angle is limited compared to conventional
>flaps, the drag increase (speedbrake effect) is smaller. This means the
>airplane floats longer in ground effect on landing, making short field
>landings more difficult.
>
>A pilot friend had a Rans S-10 Sakota with flaperons. He told me he rarely
>used the flap function, preferring to sideslip on approach.
>
>The French DynAero MCR-01 high performance plane (Ban-Bi in the US) was
>originally designed (in the microlight/UL version) with double slotted
>flaperons to comply with the stall speed requirement of 35 knots (65 km/h)
>even with a very small wing area. After a few years, they were able to
tweak
>the wing design to fulfil the stall speed requirement also with a
>conventional arrangement with ailerons and double slotted flaps, and this
is
>the current configuration.
>
>A number of airplanes (gliders in particular) have ailerons which are
>connected with the flaps and move with them. In these planes, the main idea
>is to be able to reduce drag with negative deflection of the ailerons
>together with the flaps. But I'd hesitate to call them flaperons in this
>case, where the wing also has separate flaps.
>
>Please correct me if I got something wrong, my practical exeprience of
>flaperons is limited to radio controlled model airplanes ;-)
>// N
>

[Larry]

"Whunicut" > wrote in message
...
> >I can recall spending many a late night out there re-rigging the control
> >surfaces on the Prowler (Navy EA-6B) when I worked in Quality Assurance.
The
> >Airframes guys would make an adjustment and we'd have to witness the
> >'throws' to ensure all was within specs. That dam Hydraulic Genny was
> >screaming and the hydraulics were whining- It's no wonder I lost most of
my
> >hearing.
> >
> >All that 'so we could 'make the flight schedule'. Now it's somebody
else's
> >turn to 'wrench on those jets'.
> >
> >
> >Larry
> >AECS (AW/SW/MTS)
> >USN 'Retired'
> >20 years if gettin 'em off the pointy end
> >AND safely home again!
> >
> You QA guys get that "partial ejection" incident in an A-6 figgered out?
:-))
> Warren,

I don't recall that particular one, but the Safety Stand-Downs we attended
ALWAYS had some real "what were they thinking" stories that always had a
'messy ending'. Sometime it was a movie, sometime just still photos (of the
aftermath), and sometimes just a long message (even a very 'dry' story in
message format can paint an accurate picture).

I recall one similar to what you've described Warren, where somebody (some
stupid maintenance guy) ejected into the hangar overhead.

A lot of my co-workers used to just climb in and out without checking the
pins- I ALWAYS checked the seat pins. I respect the power of those rocket
motors and did not want to see first-hand what they can do.

Larry
AECS (AW/SW/MTS)
USN 'Retired'
20 years if gettin 'em off the pointy end
AND safely home again!

[Robertmudd1u]

>A number of airplanes (gliders in particular) have ailerons which are
>connected with the flaps and move with them. In these planes, the main idea
>is to be able to reduce drag with negative deflection of the ailerons
>together with the flaps. But I'd hesitate to call them flaperons in this
>case, where the wing also has separate flaps.

Gliders with connected but separate flaps and ailerons are commonly referred to
as having interconnected flaps and ailerons. This is a very common system on
gliders that have flaps, not all do.

In the negative flap position the entire trailing edge is at a negative
setting. This reduces drag and increases performance. When applying positive
flap the ailerons also drop with the flap so that the entire trailing edge is
at a positive flap setting. The ailerons still work as ailerons separately from
the flap on some gliders.

On a glider such as the ASW-20 you have to see the interconnect system to
believe it. As the flaps go to positive positions so do the ailerons then as
the flap is put further down to the landing position the ailerons go back up to
a neutral or almost neutral setting thus reducing the angle of attack at the
tips and allowing for better lateral control during the landing roll. When the
control stick is moved laterally, for roll, the flaps and ailerons deflect
together but at different rates. Truly an amazing system and I always think of
it whenever someone mentions how "simple" gliders are.

Robert Mudd

[Nils Rostedt]

"Robertmudd1u" wrote
>
> On a glider such as the ASW-20 you have to see the interconnect system to
> believe it. As the flaps go to positive positions so do the ailerons then
as
> the flap is put further down to the landing position the ailerons go back
up to
> a neutral or almost neutral setting thus reducing the angle of attack at
the
> tips and allowing for better lateral control during the landing roll. When
the
> control stick is moved laterally, for roll, the flaps and ailerons deflect
> together but at different rates. Truly an amazing system and I always
think of
> it whenever someone mentions how "simple" gliders are.
>
Speaking of gliders, I wonder if any gliders have an arrangement whereby
both ailerons can be moved in unison to a really high negative (up) angle,
in effect acting as spoilers or speedbrakes. This was available on a
Multplex radio control system I had in the late eighties, using electronic
mixing (aileron control was of course still available) . I think it was
called "scarecrow mode" or something similar. The advantage would be that
separate speedbrakes are not needed. But in a full scale glider it might be
hard on the hinges and cause too big wingtip twist?

// N

[Whunicut]

> recall one similar to what you've described Warren, where somebody (some
>stupid maintenance guy) ejected into the hangar overhead.
>

Is this the one where the retracted basketball net kept him from falling back
to the deck?
CV45, off coast of Korea. F9F. I was there but did not see it.
Warren

[Dave Hyde]

Nils Rostedt wrote...

> Speaking of gliders, I wonder if any gliders have
> an arrangement whereby both ailerons can be moved
> in unison to a really high negative (up) angle,
> in effect acting as spoilers or speedbrakes...

What you describe sounds like "crow" mixing,
where the flaps go down and the ailerons (both)
reflex up. It's still used in RC gliders, and
given that there are several powered airplanes
that use it or something similar I'd bet that
there are full-size gliders that use it as well.
There's also trailing edge reflex, where flaps
and ailerons all move *slightly* trailing edge up,
but not a lot, and that's for drag reduction in
cruise, not drag increase for approach. Some
full-size gliders use this as well.

Dave 'poor man's DLC' Hyde

[Bill Daniels]

"Dave Hyde" > wrote in message
...
> Nils Rostedt wrote...
>
> > Speaking of gliders, I wonder if any gliders have
> > an arrangement whereby both ailerons can be moved
> > in unison to a really high negative (up) angle,
> > in effect acting as spoilers or speedbrakes...
>
> What you describe sounds like "crow" mixing,
> where the flaps go down and the ailerons (both)
> reflex up. It's still used in RC gliders, and
> given that there are several powered airplanes
> that use it or something similar I'd bet that
> there are full-size gliders that use it as well.
> There's also trailing edge reflex, where flaps
> and ailerons all move *slightly* trailing edge up,
> but not a lot, and that's for drag reduction in
> cruise, not drag increase for approach. Some
> full-size gliders use this as well.
>
> Dave 'poor man's DLC' Hyde
>
>
>
>
>

The most successful high-drag device is a Shempp-Hirth trailing edge dive
brake. The half span flaps go to 80 degrees down and a surface of equal
span and width rotates up from the upper wing surface on the same hinge line
as the flaps. This results in a surface twice the chord of the flaps at
right angles to the airflow. The effect is dramatic. Several pilots have
had police meet them on the ground after landing to investigate the 'crash'.

The view from the cockpit is scary at first. The nose is so far down that
it looks like a 'lawn dart' maneuver. Precision spot landings are very easy
when you get the hang of it. Just aim the nose at the touch down spot. If
you see you are long, just push the nose further down - the airspeed won't
increase. The flare has to be timed right but the feel is very slow and
"floaty" with a soft touchdown and short roll. You get the feeling that you
could land on a 'postage stamp'.

Bill Daniels

[Wayne Paul]

"Bill Daniels" > wrote in message
news:GILld.337003$wV.41042@attbi_s54...
>
> The most successful high-drag device is a Shempp-Hirth trailing edge dive
> brake. The half span flaps go to 80 degrees down and a surface of equal
> span and width rotates up from the upper wing surface on the same hinge
line
> as the flaps. This results in a surface twice the chord of the flaps at
> right angles to the airflow. The effect is dramatic. Several pilots have
> had police meet them on the ground after landing to investigate the
'crash'.
>
> The view from the cockpit is scary at first. The nose is so far down that
> it looks like a 'lawn dart' maneuver. Precision spot landings are very
easy
> when you get the hang of it. Just aim the nose at the touch down spot.
If
> you see you are long, just push the nose further down - the airspeed won't
> increase. The flare has to be timed right but the feel is very slow and
> "floaty" with a soft touchdown and short roll. You get the feeling that
you
> could land on a 'postage stamp'.
>
> Bill Daniels
>

Though off the subject. The approach described above is similar to that
experienced in sailplanes that depend solely on large span flaps. (SGS 1-35,
PIK-20B and the Schreder HP/RS/RHJ series.) For example, a Schreder HP-14's
40:1 glide ratio is decreased to 2:1 when the flaps are lowered to 90
degrees. This gives an approach angle of 30 degrees which requires the nose
to be 45 degrees below the horizon. It takes some getting use to; however,
once mastered it makes short field landings "a piece of cake".

See:
http://www.soaridaho.com/Schreder/HP-14/FLIGHT_TESTING_THE_14.html
http://www.soaridaho.com/Schreder/Stories/Preparing_for_first_HP_flight.htm
http://www.soaridaho.com/Schreder/Large-span_flaps.html
(Other stories can be found at:
http://www.soaridaho.com/Schreder/Schreder_Sailplane_Stories.html)

Wayne
http://www.soaridaho.com/Schreder

[Marc J. Zeitlin]

Wayne Paul wrote:

> ..... For example, a Schreder HP-14's
> 40:1 glide ratio is decreased to 2:1 when the flaps are lowered to 90
> degrees.

Wow! That's an amazing change.

>...This gives an approach angle of 30 degrees which requires the nose
> to be 45 degrees below the horizon.

I think you've got this a little backwards - if the approach angle is 30
degrees, the nose can't be BELOW that - you'd have a negative angle of
attack. I think that the nose would be somewhere in the 20 degree down
range, to provide a positive AOA of somewhere around 10 degrees. 20
degrees nose down is VERY down, however - it would certainly LOOK like
you're pointing straight down.....

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004

[Wayne Paul]

"Marc J. Zeitlin" > wrote in message
news:PiPld.610968$8_6.562540@attbi_s04...
> Wayne Paul wrote:
>
> > ..... For example, a Schreder HP-14's
> > 40:1 glide ratio is decreased to 2:1 when the flaps are lowered to 90
> > degrees.
>
> Wow! That's an amazing change.
>
> >...This gives an approach angle of 30 degrees which requires the nose
> > to be 45 degrees below the horizon.
>
> I think you've got this a little backwards - if the approach angle is 30
> degrees, the nose can't be BELOW that - you'd have a negative angle of
> attack. I think that the nose would be somewhere in the 20 degree down
> range, to provide a positive AOA of somewhere around 10 degrees. 20
> degrees nose down is VERY down, however - it would certainly LOOK like
> you're pointing straight down.....
>

The stall speed of a HP-14 with a 90 degree flap setting is only 30 mph.
The approach is flown at 55 mph (the best L/D speed with 0 degree flap
setting) to provide the ability to take of a little flap while raising the
nose if you are tracking short of the desired touch down point. Lowering
the flaps changes the effective angle of incidence of the wing with
relationship to the fuselage. In the case of the HP-14 this is about 15
degrees.

The attitude of the HP-14 sitting on the runway is the approximate attitude
at which it stalls with a 90 degree flap setting. As you fly the approach
at 55 with full flap you look landing aim point is well above the nose of
the glider. In fact it is almost up to the canopy bow.

(Pictures of HP-14 large span flaps:
http://www.soaridaho.com/Schreder/HP-14/N8041/N8041_1.jpg more links
http://www.soaridaho.com/Schreder/HP-14/HP-14_Links.html)

Respectfully,
Wayne
http://www.soaridaho.com/Schreder

[Alan Baker]

In article <PiPld.610968$8_6.562540@attbi_s04>,
"Marc J. Zeitlin" > wrote:

> Wayne Paul wrote:
>
> > ..... For example, a Schreder HP-14's
> > 40:1 glide ratio is decreased to 2:1 when the flaps are lowered to 90
> > degrees.
>
> Wow! That's an amazing change.
>
> >...This gives an approach angle of 30 degrees which requires the nose
> > to be 45 degrees below the horizon.
>
> I think you've got this a little backwards - if the approach angle is 30
> degrees, the nose can't be BELOW that - you'd have a negative angle of
> attack. I think that the nose would be somewhere in the 20 degree down
> range, to provide a positive AOA of somewhere around 10 degrees. 20
> degrees nose down is VERY down, however - it would certainly LOOK like
> you're pointing straight down.....

You're forgetting the effect of lowering the flaps on the actual as
opposed to nominal AOA of the wings.

Ask yourself how much you'd have to lower the nose after lowering the
flaps in order to (for instance) stay at the zero lift AOA relative to
the fuselage...

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."