KR> forward sweep

[Tim]

Rearward sweep is sometimes used for in a correction for W I'm thinking 
the wooden Spencer Aircar Amphib. It was repowered w/ a bigger engine & has 
a 3200lbs gross wt nd a sweep was put in...


- Original Message - 
From: "Hall, Rodney CTR NNSY, C210" <rodney.r.hall@navy.mil>
To: "KRnet" <kr...@mylist.net>
Sent: Friday, July 16, 2010 8:26 AM
Subject: RE: KR> forward sweep


Forward sweep has been used on Amateur built aircraft before. The Cygnet has 
a touch of forward sweep as does the Schleicher K-8 glider. A small amount 
of forward sweep does not require sophisticated computer controls however 
deviating from the designers plans, especially with a proven design such as 
the KR-2 can be very, very dangerous. A seemingly insignificant amount of 
change in the wing geometry could cause unforeseen stability problems or 
cause the plane to become uncontrollable in certain situations. If you don't 
like the design your building build a different design don't make untested 
changes especially with control surfaces and wings.

Rodney Hall

-Original Message-
From: krnet-bounces+rodney.r.hall.ctr=navy@mylist.net 
[mailto:krnet-bounces+rodney.r.hall.ctr=navy@mylist.net] On Behalf Of 
Hal Dantone
Sent: Friday, July 16, 2010 9:35
To: KRnet
Subject: Re: KR> forward sweep

To Bill:
Mooney's are not unstable, and their wings do not have forward sweep. They 
are great aircraft. Their leading edge is straight (perpendicular to the CL 
of the fuselage) and their trailing edge is swept forward which gives the 
appearance of forward sweep, but it is the leading edge that matters.
Hal

--- On Fri, 7/16/10, Tim <t...@telus.net> wrote:

From: Tim <t...@telus.net>
Subject: Re: KR> forward sweep
To: "KRnet" <kr...@mylist.net>
List-Post: krnet@list.krnet.org
Date: Friday, July 16, 2010, 10:11 AM


Back around 1988, Mike Sacoutis bought a wood wing Mooney off a Grass 
Airstrip. It had sat there 'outside' for years.

After some maintenance, he talked 'Serge' German war Test Pilot, to fly it 
back to our Airport, approx 10 miles..Serge did, uneventfully.Within 
a week a huge wind storm, lifted the Mooney up & thru it ontop of the 
Airport's 8' chain link fence.

Both wings were snapped off, exposing inside the box spar, a friggin 
Mushroom farm. In places you could poke yer finger through the web.Serge 
was upset with Mike> "That's the last GD time I'm ferrying your 'Junk'
Deals".Those moments in AV-U never forget ;-)

CldLk-Tim

- Original Message -
From: <zorc...@aol.com>


Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F




In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
aerona...@sbcglobal.net writes:

On a more basic note, I will add two things about forward sweep.
1. Your wings must be much stronger to handle the forces caused by the
negative stability.
2. It generally requires a computer controlled flight system to handle the
bending moments.
Not recommended.
Hal Dantone



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KR> forward sweep

[Hall, Rodney CTR NNSY, C210]

Forward sweep has been used on Amateur built aircraft before. The Cygnet has a 
touch of forward sweep as does the Schleicher K-8 glider. A small amount of 
forward sweep does not require sophisticated computer controls however 
deviating from the designers plans, especially with a proven design such as the 
KR-2 can be very, very dangerous. A seemingly insignificant amount of change in 
the wing geometry could cause unforeseen stability problems or cause the plane 
to become uncontrollable in certain situations. If you don't like the design 
your building build a different design don't make untested changes especially 
with control surfaces and wings.

Rodney Hall 

-Original Message-
From: krnet-bounces+rodney.r.hall.ctr=navy@mylist.net 
[mailto:krnet-bounces+rodney.r.hall.ctr=navy@mylist.net] On Behalf Of Hal 
Dantone
Sent: Friday, July 16, 2010 9:35
To: KRnet
Subject: Re: KR> forward sweep

To Bill: 
Mooney's are not unstable, and their wings do not have forward sweep.  They are 
great aircraft.  Their leading edge is straight (perpendicular to the CL of the 
fuselage) and their trailing edge is swept forward which gives the appearance 
of forward sweep, but it is the leading edge that matters. 
Hal 

--- On Fri, 7/16/10, Tim <t...@telus.net> wrote:

From: Tim <t...@telus.net>
Subject: Re: KR> forward sweep
To: "KRnet" <kr...@mylist.net>
List-Post: krnet@list.krnet.org
Date: Friday, July 16, 2010, 10:11 AM


Back around 1988, Mike Sacoutis bought a wood wing Mooney off a Grass Airstrip. 
It had sat there 'outside' for years.

After some maintenance, he talked 'Serge' German war Test Pilot,  to fly it 
back to our Airport, approx 10 miles..Serge did, uneventfully.Within a 
week a huge wind storm, lifted the Mooney up & thru it ontop of the Airport's 
8' chain link fence.

Both wings were snapped off, exposing inside the box spar, a friggin Mushroom 
farm. In places you could poke yer finger through the web.Serge was upset 
with Mike> "That's the last GD time I'm ferrying your 'Junk' 
Deals".Those moments in AV-U never forget ;-)

CldLk-Tim

- Original Message -
From: <zorc...@aol.com>


Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F




In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
aerona...@sbcglobal.net writes:

On a  more basic note, I will add two things about forward sweep.
1. Your wings  must be much stronger to handle the forces caused by the
negative  stability.
2. It generally requires a computer controlled flight system to  handle the
bending moments.
Not recommended.
Hal  Dantone



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KR> forward sweep

[Hal Dantone]

To Bill: 
Mooney's are not unstable, and their wings do not have forward sweep.  They are 
great aircraft.  Their leading edge is straight (perpendicular to the CL of the 
fuselage) and their trailing edge is swept forward which gives the appearance 
of forward sweep, but it is the leading edge that matters. 
Hal 

--- On Fri, 7/16/10, Tim <t...@telus.net> wrote:

From: Tim <t...@telus.net>
Subject: Re: KR> forward sweep
To: "KRnet" <kr...@mylist.net>
List-Post: krnet@list.krnet.org
Date: Friday, July 16, 2010, 10:11 AM


Back around 1988, Mike Sacoutis bought a wood wing Mooney off a Grass 
Airstrip. It had sat there 'outside' for years.

After some maintenance, he talked 'Serge' German war Test Pilot,  to fly it 
back to our Airport, approx 10 miles..Serge did, uneventfully.Within 
a week a huge wind storm, lifted the Mooney up & thru it ontop of the 
Airport's 8' chain link fence.

Both wings were snapped off, exposing inside the box spar, a friggin 
Mushroom farm. In places you could poke yer finger through the web.Serge 
was upset with Mike> "That's the last GD time I'm ferrying your 'Junk' 
Deals".Those moments in AV-U never forget ;-)

CldLk-Tim

- Original Message - 
From: <zorc...@aol.com>


Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F




In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
aerona...@sbcglobal.net writes:

On a  more basic note, I will add two things about forward sweep.
1. Your wings  must be much stronger to handle the forces caused by the
negative  stability.
2. It generally requires a computer controlled flight system to  handle the
bending moments.
Not recommended.
Hal  Dantone



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KR> forward sweep

[Tim]

Back around 1988, Mike Sacoutis bought a wood wing Mooney off a Grass 
Airstrip. It had sat there 'outside' for years.

After some maintenance, he talked 'Serge' German war Test Pilot,  to fly it 
back to our Airport, approx 10 miles..Serge did, uneventfully.Within 
a week a huge wind storm, lifted the Mooney up & thru it ontop of the 
Airport's 8' chain link fence.

Both wings were snapped off, exposing inside the box spar, a friggin 
Mushroom farm. In places you could poke yer finger through the web.Serge 
was upset with Mike> "That's the last GD time I'm ferrying your 'Junk' 
Deals".Those moments in AV-U never forget ;-)

CldLk-Tim

- Original Message - 
From: 


Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F




In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
aerona...@sbcglobal.net writes:

On a  more basic note, I will add two things about forward sweep.
1. Your wings  must be much stronger to handle the forces caused by the
negative  stability.
2. It generally requires a computer controlled flight system to  handle the
bending moments.
Not recommended.
Hal  Dantone

KR> forward sweep

[Tim]

To match the lift distribution over the wing with weight distribution over 
the wing. Most aircraft have all their weight in the centre (eg. fuselage). 
The ideal match is actually an eliptical shaped wing planform but tapering 
is easier to build and is a good compromise.

If a plank flying wing aircraft had its weight evenly distributed over it's 
entire span then a constant cord would be best.

Tapered wing planforms are most often employed to approximate the ideal 
elliptical planform. Theoretically a perfectly elliptical planform enables 
every part of the wing to reach the maximum CL at the same time, which will 
result in a wing with the lowest posible drag for a given lift.

Since it is difficult to build a wing with a curved elliptical planform a 
tapered shape is often used as an approximation.

KR> forward sweep

[Larry H.]

Mooneys don't have forward swept wings, they have forward swept trailing edges 
on the main wing and the horizontal tail and both have straight leading edges , 
except the Mooneys inboard first 3 feet are tapered rearward, then outboard of 
that they are straight perpendicular to the fuselage centerline.
Mooneys are very stable.
Larry Howell







Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F

KR> FORWARD SWEEP OR CONSTANT CHORD WING

[Larry H.]

I talked to a hot shot NASA Aeronautical Engineer some years back who had been 
involved heavily in studying and testing different wing shapes on real 
airplanes. He said if your airplane design would not exceed 250 miles per hour 
that tapering a wing might look cool but it gained you absolutely nothing. He 
said you may as well make it easy on yourself and build a CONSTANT CHORD WING 
AIRPLANE. While we can dream and wish, guys like him actually had our tax 
dollars and lots of people on their teams to actually go and do this testing.
I know why all the early models if not all Vans aircraft models have a 
rectangular constant chord wing, easy to make parts!

He also talked about drag in the engine compartment. I do not remember the 
percentage now but the largest drag on a piston powered airplane, probably all 
others as well is in the engine compartment. Figure out a way to move the 
engine 
cooling air through the engine compartment less draggy and more efficiently and 
you will use less fuel for same speed or go faster.

Larry Howell

KR> forward sweep

[Joe Coggiano]

Hope nobody minds my 2 cents. Military speaking swept wing aircraft normally 
will not change wing position until higher speeds are attained. This is
where maximum advantage is attained. The advantage at lower speeds is 
negligible 
for the expense.

However I am not familiar with low speed homebuilds along these lines. It has 
been many years so my observations may be all  wet.
Joe





From: J L <schml...@gmail.com>
To: KRnet <kr...@mylist.net>
Sent: Mon, July 12, 2010 11:47:44 AM
Subject: Re: KR> forward sweep

I have a model airplane that has about 10 degrees of forward sweep.
Flies normally. However the wing is extremely stiff and will still
flutter at high speed (150mph) if the ailerons have any slop in them.

On 7/12/10, zorc...@aol.com <zorc...@aol.com> wrote:
> Then I guess every Mooney out there must be terribly unstable
>
> Bill Zorc
> Vero Beach, FL
> RV-8 N2046F
>
>
>
>
> In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
> aerona...@sbcglobal.net writes:
>
> On a  more basic note, I will add two things about forward sweep.
> 1. Your wings  must be much stronger to handle the forces caused by the
> negative  stability.
> 2. It generally requires a computer controlled flight system to  handle the
> bending moments.
> Not recommended.
> Hal  Dantone
>
> --- On Mon, 7/12/10, Mark Langford <n5...@hiwaay.net>  wrote:
>
> From: Mark Langford <n5...@hiwaay.net>
> Subject: Re:  KR> forward sweep
> To: "KRnet" <kr...@mylist.net>
> Date: Monday,  July 12, 2010, 2:38 PM
>
> I don't remember the exact reason, but I read in  a Raymer aircraft design
> book that any kind of forward sweep was a bad  idea on general aviation
> aircraft, for various reasons including stability  and stall
> characteristics.
> We're talking forward sweep though, not just  "no" sweep.
>
> Below is something I snagged off the  web:
>
> Advantages
>
> a.. Better off-design span loading (but  with less taper: Cl advantage,
> weight penalty)
>
> b..  Aeroelastically enhanced maneuverability
>
> c.. Smaller basic lift  distribution
>
> d.. Reduced leading edge sweep for given structural  sweep
>
> e.. Increased trailing edge sweep for given structural  sweep - lower CDc
>
> f.. Unobstructed cabin
>
> g.. Easy  gear placement
>
> h.. Good for turboprop placement
>
> i.. Laminar flow advantages?
>
>
> Disadvantages
>
> a..  Aeroelastic divergence or penalty to avoid it
>
> b.. Lower |Cl?|  (effective dihedral)
>
> c.. Lower Cn? (yaw stability)
>
> d.. Bad for winglets
>
> e.. Stall location (more  difficult)
>
> f.. Large Cm0 with flaps
>
> g.. Reduced  pitch stability due to additional lift and fuse interference
>
> h..  Smaller tail length???
>
> Mark Langford
> n5...@hiwaay.net
> website  www.n56ml.com
>
>
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KR> forward sweep

[J L]

I have a model airplane that has about 10 degrees of forward sweep.
Flies normally. However the wing is extremely stiff and will still
flutter at high speed (150mph) if the ailerons have any slop in them.

On 7/12/10, zorc...@aol.com <zorc...@aol.com> wrote:
> Then I guess every Mooney out there must be terribly unstable
>
> Bill Zorc
> Vero Beach, FL
> RV-8 N2046F
>
>
>
>
> In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,
> aerona...@sbcglobal.net writes:
>
> On a  more basic note, I will add two things about forward sweep.
> 1. Your wings  must be much stronger to handle the forces caused by the
> negative  stability.
> 2. It generally requires a computer controlled flight system to  handle the
> bending moments.
> Not recommended.
> Hal  Dantone
>
> --- On Mon, 7/12/10, Mark Langford <n5...@hiwaay.net>  wrote:
>
> From: Mark Langford <n5...@hiwaay.net>
> Subject: Re:  KR> forward sweep
> To: "KRnet" <kr...@mylist.net>
> Date: Monday,  July 12, 2010, 2:38 PM
>
> I don't remember the exact reason, but I read in  a Raymer aircraft design
> book that any kind of forward sweep was a bad  idea on general aviation
> aircraft, for various reasons including stability  and stall
> characteristics.
> We're talking forward sweep though, not just  "no" sweep.
>
> Below is something I snagged off the  web:
>
> Advantages
>
> a.. Better off-design span loading (but  with less taper: Cl advantage,
> weight penalty)
>
> b..  Aeroelastically enhanced maneuverability
>
> c.. Smaller basic lift  distribution
>
> d.. Reduced leading edge sweep for given structural  sweep
>
> e.. Increased trailing edge sweep for given structural  sweep - lower CDc
>
> f.. Unobstructed cabin
>
> g.. Easy  gear placement
>
> h.. Good for turboprop placement
>
> i.. Laminar flow advantages?
>
>
> Disadvantages
>
> a..  Aeroelastic divergence or penalty to avoid it
>
> b.. Lower |Cl?|  (effective dihedral)
>
> c.. Lower Cn? (yaw stability)
>
> d.. Bad for winglets
>
> e.. Stall location (more  difficult)
>
> f.. Large Cm0 with flaps
>
> g.. Reduced  pitch stability due to additional lift and fuse interference
>
> h..  Smaller tail length???
>
> Mark Langford
> n5...@hiwaay.net
> website  www.n56ml.com
>
>
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>

KR> forward sweep

[zorc...@aol.com]

Then I guess every Mooney out there must be terribly unstable

Bill Zorc
Vero Beach, FL
RV-8 N2046F




In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time,  
aerona...@sbcglobal.net writes:

On a  more basic note, I will add two things about forward sweep.
1. Your wings  must be much stronger to handle the forces caused by the 
negative  stability.
2. It generally requires a computer controlled flight system to  handle the 
bending moments.  
Not recommended.  
Hal  Dantone

--- On Mon, 7/12/10, Mark Langford <n5...@hiwaay.net>  wrote:

From: Mark Langford <n5...@hiwaay.net>
Subject: Re:  KR> forward sweep
To: "KRnet" <kr...@mylist.net>
List-Post: krnet@list.krnet.org
Date: Monday,  July 12, 2010, 2:38 PM

I don't remember the exact reason, but I read in  a Raymer aircraft design 
book that any kind of forward sweep was a bad  idea on general aviation 
aircraft, for various reasons including stability  and stall 
characteristics. 
We're talking forward sweep though, not just  "no" sweep.

Below is something I snagged off the  web:

Advantages

a.. Better off-design span loading (but  with less taper: Cl advantage, 
weight penalty)

b..  Aeroelastically enhanced maneuverability

c.. Smaller basic lift  distribution

d.. Reduced leading edge sweep for given structural  sweep

e.. Increased trailing edge sweep for given structural  sweep - lower CDc

f.. Unobstructed cabin

g.. Easy  gear placement

h.. Good for turboprop placement

i.. Laminar flow advantages?


Disadvantages

a..  Aeroelastic divergence or penalty to avoid it

b.. Lower |Cl?|  (effective dihedral)

c.. Lower Cn? (yaw stability)

d.. Bad for winglets

e.. Stall location (more  difficult)

f.. Large Cm0 with flaps

g.. Reduced  pitch stability due to additional lift and fuse interference

h..  Smaller tail length???

Mark Langford
n5...@hiwaay.net
website  www.n56ml.com


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KR> forward sweep

[Fred Johnson]

I'll put my two cents on this;

Perhaps if we were talking 15 or 20 degrees of forward sweep you guys would
be correct, but I would like to point out that there have been several
sailplanes with forward sweep, the "Genesis" is one and Jim Marske has
designed several too. they have less than 5 degrees of forward sweep and are
TAILLESS... (the "Genesis" has a very small tail for pitch control)

For a KR "type" of airplane with say 3 degrees of "Leading Edge" forward
sweep wouldn't be hard and it wouldn't be UNSTABLE as it is all about
balancing forces. It's not like it's an X-29 or a Cornelius Mallard. And
might I add that the Bugatti model 100 had a small amount of forward
sweep...check it out at OSH this year, it's in there museum.

I do AGREE with Mark L though, it's not a KR anymore...

Fred Johnson
Reno, NV



Hal wrote:

On a more basic note, I will add two things about forward sweep.
1. Your wings must be much stronger to handle the forces caused by the
negative stability.
2. It generally requires a computer controlled flight system to handle the
bending moments.  
Not recommended.  
Hal Dantone

KR> forward sweep

[Hal Dantone]

On a more basic note, I will add two things about forward sweep.
1. Your wings must be much stronger to handle the forces caused by the negative 
stability.
2. It generally requires a computer controlled flight system to handle the 
bending moments.  
Not recommended.  
Hal Dantone

--- On Mon, 7/12/10, Mark Langford <n5...@hiwaay.net> wrote:

From: Mark Langford <n5...@hiwaay.net>
Subject: Re: KR> forward sweep
To: "KRnet" <kr...@mylist.net>
List-Post: krnet@list.krnet.org
Date: Monday, July 12, 2010, 2:38 PM

I don't remember the exact reason, but I read in a Raymer aircraft design 
book that any kind of forward sweep was a bad idea on general aviation 
aircraft, for various reasons including stability and stall characteristics. 
We're talking forward sweep though, not just "no" sweep.

Below is something I snagged off the web:

Advantages

  a.. Better off-design span loading (but with less taper: Cl advantage, 
weight penalty)

  b.. Aeroelastically enhanced maneuverability

  c.. Smaller basic lift distribution

  d.. Reduced leading edge sweep for given structural sweep

  e.. Increased trailing edge sweep for given structural sweep - lower CDc

  f.. Unobstructed cabin

  g.. Easy gear placement

  h.. Good for turboprop placement

  i.. Laminar flow advantages?


Disadvantages

  a.. Aeroelastic divergence or penalty to avoid it

  b.. Lower |Cl?| (effective dihedral)

  c.. Lower Cn? (yaw stability)

  d.. Bad for winglets

  e.. Stall location (more difficult)

  f.. Large Cm0 with flaps

  g.. Reduced pitch stability due to additional lift and fuse interference

  h.. Smaller tail length???

Mark Langford
n5...@hiwaay.net
website www.n56ml.com


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KR> forward sweep

[Mark Langford]

I don't remember the exact reason, but I read in a Raymer aircraft design 
book that any kind of forward sweep was a bad idea on general aviation 
aircraft, for various reasons including stability and stall characteristics. 
We're talking forward sweep though, not just "no" sweep.

Below is something I snagged off the web:

Advantages

  a.. Better off-design span loading (but with less taper: Cl advantage, 
weight penalty)

  b.. Aeroelastically enhanced maneuverability

  c.. Smaller basic lift distribution

  d.. Reduced leading edge sweep for given structural sweep

  e.. Increased trailing edge sweep for given structural sweep - lower CDc

  f.. Unobstructed cabin

  g.. Easy gear placement

  h.. Good for turboprop placement

  i.. Laminar flow advantages?


Disadvantages

  a.. Aeroelastic divergence or penalty to avoid it

  b.. Lower |Cl?| (effective dihedral)

  c.. Lower Cn? (yaw stability)

  d.. Bad for winglets

  e.. Stall location (more difficult)

  f.. Large Cm0 with flaps

  g.. Reduced pitch stability due to additional lift and fuse interference

  h.. Smaller tail length???

Mark Langford
n5...@hiwaay.net
website www.n56ml.com