Hershey bar wing vs composite wing - how much drag?

"cavelamb himself" wrote ...
At these speeds I suspect surface condition is a small part of the
overall drag.

However!

If the new wing were a couple hundred pounds lighter, then you'd
see some inprovement in speed.

It takes power to stay aloft.

The heavier the plane, the more power is required just to stay up.


Richard,

That's not really true for a light airplane. The only place weight shows up
in the drag equation, and thus the power equation, is in the induced drag
term.
But,because the wing on a light airplane is relatively large, the induced
drag at cruise is small. Cruise induced drag is lift coeffients squared
divided Pi e Aspect Ratio. Light airplanes cruise at small lift coeffients
of around 0.1 to 0.2. It can be shown that they will fly the farthest on a
pound of fuel at L/D max. Lift coeffients around 0.6 to 0.8. So, an
increase in airframe weight doesn't increase the cruise power requirements
very much.

Of course, an light airplane could be designed to fly at L/D max but the
wing would be tiny and you'd pay for it on the slow speed end. With a
single engine and relatively inexperienced pilots, it would be a handful at
slow speeds. Both the BD-5 and the Questar venture are examples of under
winged airplanes that have poor engine out safety records.

Where weight does show up is in climb performance. One of the things that
make an airplane "fun" is how well it climbs. You don't spend much time
there in a cross country flight, but a large high aspect ratio wing with
lots of power will give the pilot the feeling that the airplane is a good
flying airplane.

One of the problems I've had in the past is how much should a designer try
to protect a future user of a product? I've decided that a minimalist wing
is a bad design in the light plane market.

Rich

On Mar 28, 8:51 am, Nathan Young wrote:
I have a Cherokee 180, with the short hershey bar wing. While I love
the plane, I always wish it could go a bit faster, or use a bit less
fuel to get to my destination.

I have followed the composite homebuilding movement for many years,
and am amazed at the sleekness of a composite wing. The wings on most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing gear
structure.

So my question: How much drag does a wing on a Hersey Bar Cherokee
generate, and and hypothetically speaking, how much faster could the
plane go if it was retooled with a sleek, composite wing?

I can't remember if it was Kitplanes or SportAviation that had a
recent article on a Piper knockoff being produced as a kitplane in
South Africa. That might be a good starting point for the difference
in performance between the different planes as well as a discussion of
the differences in design and construction. Much of the difference
has to do with better airfoil designs being used but also weight
differences.

"BobR" wrote in news:1175092590.355514.234030
@y80g2000hsf.googlegroups.com:

On Mar 28, 8:51 am, Nathan Young wrote:
I have a Cherokee 180, with the short hershey bar wing. While I love
the plane, I always wish it could go a bit faster, or use a bit less
fuel to get to my destination.

I have followed the composite homebuilding movement for many years,
and am amazed at the sleekness of a composite wing. The wings on
most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing
gear
structure.

So my question: How much drag does a wing on a Hersey Bar Cherokee
generate, and and hypothetically speaking, how much faster could the
plane go if it was retooled with a sleek, composite wing?

I can't remember if it was Kitplanes or SportAviation that had a
recent article on a Piper knockoff being produced as a kitplane in
South Africa. That might be a good starting point for the difference
in performance between the different planes as well as a discussion of
the differences in design and construction. Much of the difference
has to do with better airfoil designs being used but also weight
differences.


Well, that airplane is "inspired" by the Commanche and it's really just
comparing apples and oranges since there are so many other differences
in the two airplanes, but having said that, it's better than comparing a
cherokee to a Cozy, for instance..

In any case, the Ravin Commanche is here
http://www.saravin.com/review.htm

ALC

On Mar 28, 12:40 pm, Alphonse Le Creur wrote:
"BobR" wrote in news:1175092590.355514.234030
@y80g2000hsf.googlegroups.com:







On Mar 28, 8:51 am, Nathan Young wrote:
I have a Cherokee 180, with the short hershey bar wing. While I love
the plane, I always wish it could go a bit faster, or use a bit less
fuel to get to my destination.

I have followed the composite homebuilding movement for many years,
and am amazed at the sleekness of a composite wing. The wings on
most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing
gear
structure.

So my question: How much drag does a wing on a Hersey Bar Cherokee
generate, and and hypothetically speaking, how much faster could the
plane go if it was retooled with a sleek, composite wing?

I can't remember if it was Kitplanes or SportAviation that had a
recent article on a Piper knockoff being produced as a kitplane in
South Africa. That might be a good starting point for the difference
in performance between the different planes as well as a discussion of
the differences in design and construction. Much of the difference
has to do with better airfoil designs being used but also weight
differences.

Well, that airplane is "inspired" by the Commanche and it's really just
comparing apples and oranges since there are so many other differences
in the two airplanes, but having said that, it's better than comparing a
cherokee to a Cozy, for instance..

In any case, the Ravin Commanche is herehttp://www.saravin.com/review.htm

ALC- Hide quoted text -

- Show quoted text -

It's about as close a comparison as can be made. I am building the
KIS Cruiser which uses a hershey bar style wing as well but the
airfoil is different. The comparison from a performance standpoint is
much faster than the Commanche for the same power (180 hp). The
difference must be attributed to several differences beyond just the
wing, weight being the most obvious.

"BobR" wrote in
ups.com:

On Mar 28, 12:40 pm, Alphonse Le Creur wrote:
"BobR" wrote in
news:1175092590.355514.234030 @y80g2000hsf.googlegroups.com:







On Mar 28, 8:51 am, Nathan Young
wrote:
I have a Cherokee 180, with the short hershey bar wing. While I
love the plane, I always wish it could go a bit faster, or use a
bit less fuel to get to my destination.

I have followed the composite homebuilding movement for many
years, and am amazed at the sleekness of a composite wing. The
wings on
most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing
gear
structure.

So my question: How much drag does a wing on a Hersey Bar
Cherokee generate, and and hypothetically speaking, how much
faster could the plane go if it was retooled with a sleek,
composite wing?

I can't remember if it was Kitplanes or SportAviation that had a
recent article on a Piper knockoff being produced as a kitplane in
South Africa. That might be a good starting point for the
difference in performance between the different planes as well as a
discussion of the differences in design and construction. Much of
the difference has to do with better airfoil designs being used but
also weight differences.

Well, that airplane is "inspired" by the Commanche and it's really
just comparing apples and oranges since there are so many other
differences in the two airplanes, but having said that, it's better
than comparing a cherokee to a Cozy, for instance..

In any case, the Ravin Commanche is
herehttp://www.saravin.com/review.htm

ALC- Hide quoted text -

- Show quoted text -

It's about as close a comparison as can be made. I am building the
KIS Cruiser which uses a hershey bar style wing as well but the
airfoil is different. The comparison from a performance standpoint is
much faster than the Commanche for the same power (180 hp). The
difference must be attributed to several differences beyond just the
wing, weight being the most obvious.

Well, the Ravin is actually a couple hundred pounds heavier than the
original Commanche empty and has a higher gross. It also has a much
smaller fuselage cross section.
I'm certainly not saying that the Ravin is not a better airplane. It is.
I'd sure like to have one! I'm just saying that while it is probably one
of the better comparisons, no absolute conclusion may be made from it.
There's too many other things going on there. The Commanche uses what
was a then state of the art NACA 6 series laminar flow airfoil. It was
streets ahead of what was on any lightplane of the time, but it's use
was most probably not dictated by the material of which it was made. I
have no idea what the Ravin is using for an airfoil.
If Piper were to set out to make the same airplane again today using
aluminum for the wing, they could still build a more efficient wing than
they did in the fifties by simple virtue of the fact that fifty years
later there's been quite a lot of innovation in airfoils, structures and
what not. Again, I'm not saying that the Ravin isn't a better airplane,
nor am I denying that composites might be a better way to build an
airplane, just saying (at the risk of flogging the proverbial dead
horse) that the comparison , while it is as good as you're going to get,
is still flawed.


ALC

On Mar 28, 4:35 pm, Alphonse Le Creur wrote:
"BobR" wrote roups.com:





On Mar 28, 12:40 pm, Alphonse Le Creur wrote:
"BobR" wrote in
news:1175092590.355514.234030 @y80g2000hsf.googlegroups.com:

On Mar 28, 8:51 am, Nathan Young
wrote:
I have a Cherokee 180, with the short hershey bar wing. While I
love the plane, I always wish it could go a bit faster, or use a
bit less fuel to get to my destination.

I have followed the composite homebuilding movement for many
years, and am amazed at the sleekness of a composite wing. The
wings on
most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing
gear
structure.

So my question: How much drag does a wing on a Hersey Bar
Cherokee generate, and and hypothetically speaking, how much
faster could the plane go if it was retooled with a sleek,
composite wing?

I can't remember if it was Kitplanes or SportAviation that had a
recent article on a Piper knockoff being produced as a kitplane in
South Africa. That might be a good starting point for the
difference in performance between the different planes as well as a
discussion of the differences in design and construction. Much of
the difference has to do with better airfoil designs being used but
also weight differences.

Well, that airplane is "inspired" by the Commanche and it's really
just comparing apples and oranges since there are so many other
differences in the two airplanes, but having said that, it's better
than comparing a cherokee to a Cozy, for instance..

In any case, the Ravin Commanche is
herehttp://www.saravin.com/review.htm

ALC- Hide quoted text -

- Show quoted text -

It's about as close a comparison as can be made. I am building the
KIS Cruiser which uses a hershey bar style wing as well but the
airfoil is different. The comparison from a performance standpoint is
much faster than the Commanche for the same power (180 hp). The
difference must be attributed to several differences beyond just the
wing, weight being the most obvious.

Well, the Ravin is actually a couple hundred pounds heavier than the
original Commanche empty and has a higher gross. It also has a much
smaller fuselage cross section.
I'm certainly not saying that the Ravin is not a better airplane. It is.
I'd sure like to have one! I'm just saying that while it is probably one
of the better comparisons, no absolute conclusion may be made from it.
There's too many other things going on there. The Commanche uses what
was a then state of the art NACA 6 series laminar flow airfoil. It was
streets ahead of what was on any lightplane of the time, but it's use
was most probably not dictated by the material of which it was made. I
have no idea what the Ravin is using for an airfoil.
If Piper were to set out to make the same airplane again today using
aluminum for the wing, they could still build a more efficient wing than
they did in the fifties by simple virtue of the fact that fifty years
later there's been quite a lot of innovation in airfoils, structures and
what not. Again, I'm not saying that the Ravin isn't a better airplane,
nor am I denying that composites might be a better way to build an
airplane, just saying (at the risk of flogging the proverbial dead
horse) that the comparison , while it is as good as you're going to get,
is still flawed.

ALC- Hide quoted text -

- Show quoted text -

Agreed, you will always be dealing with differences that can skew the
comparison including differing prop combinations. Another good
comparison might be VANS RV-10 which does use a metal wing. The
performance numbers on that plane are also better than the
Commanchee. The RV-10 is probably a good comparison to the Ravin
since both would probably be about the same weight, size, and use the
same engine. The RV-10 with the O-360 combination might be a good
comparison to the commanchee.

On Mar 28, 6:51 am, Nathan Young wrote:
I have a Cherokee 180, with the short hershey bar wing. While I love
the plane, I always wish it could go a bit faster, or use a bit less
fuel to get to my destination.

I have followed the composite homebuilding movement for many years,
and am amazed at the sleekness of a composite wing. The wings on most
composites tend to be the complete opposite of a Hersey bar wing:
high aspect ratio, low thickness, no rivets, no screws for fuel
tanks,smooth curves faired into airframe, and streamlined landing gear
structure.

So my question: How much drag does a wing on a Hersey Bar Cherokee
generate, and and hypothetically speaking, how much faster could the
plane go if it was retooled with a sleek, composite wing?

A fast Cherokee is also known as a Mooney C model.

-Robert

Robert M. Gary wrote:

A fast Cherokee is also known as a Mooney C model.

Hm...I always thought "fast cherokee" was an oxymoron...

And yes, I own a cherokee 180. Would I like faster? Sure! Wouldn't
everyone?

On Mar 28, 12:30 pm, Blanche wrote:
Robert M. Gary wrote:



A fast Cherokee is also known as a Mooney C model.

Hm...I always thought "fast cherokee" was an oxymoron...

And yes, I own a cherokee 180. Would I like faster? Sure! Wouldn't
everyone?

I think part of my point is that the price of the 180 and the M20C are
pretty close. I'm not sure why people choose the 180 when its a good
30 knots slower on the same fuel burn.

-Robert

Robert M. Gary wrote:
On Mar 28, 12:30 pm, Blanche wrote:
Robert M. Gary wrote:



A fast Cherokee is also known as a Mooney C model.

Hm...I always thought "fast cherokee" was an oxymoron...

And yes, I own a cherokee 180. Would I like faster? Sure! Wouldn't
everyone?

I think part of my point is that the price of the 180 and the M20C are
pretty close. I'm not sure why people choose the 180 when its a good
30 knots slower on the same fuel burn.

-Robert

I agree with you but I'd bet insurance and the cost of up keep added because
of the retrac gear has a lot to do with it.