Hershey bar wing vs composite wing - how much drag?

And a LOT of the drag is from cooling the engine!
There is an ideal place for big gains.

Yes, look at the difference in performance of the J model Mooneys vs.
the pre-J models.

("cavelamb himself" wrote)
And a LOT of the drag is from cooling the engine!
There is an ideal place for big gains.


Ercoupe, Cessna 172, Piper Warrior:
How much drag would be eliminated it the prop was spun from, say, a
(hypothetically capable) electric motor - of the same weight as the engine?
An electric motor that needs little of the cooling air (drag) required by
the gas engines.

WAG, is a LOT ...33%?

Whatever the guesstimated drag number settled on, what then would that
number mean in cruise speeds, or fuel burn? 10% improvement? 20%
improvement? 30%?


Montblack

"Montblack" wrote in message
...
("cavelamb himself" wrote)
And a LOT of the drag is from cooling the engine!
There is an ideal place for big gains.


Ercoupe, Cessna 172, Piper Warrior:
How much drag would be eliminated it the prop was spun from, say, a
(hypothetically capable) electric motor - of the same weight as the
engine? An electric motor that needs little of the cooling air (drag)
required by the gas engines.

WAG, is a LOT ...33%?

Whatever the guesstimated drag number settled on, what then would that
number mean in cruise speeds, or fuel burn? 10% improvement? 20%
improvement? 30%?


Montblack

You're on the right track if you can work with a semi-trailer sized battery
or a 500 mile extension cord. ;-)

KB

("Kyle Boatright" wrote)
You're on the right track if you can work with a semi-trailer sized
battery...


I'm putting you down for 18%.


Montblack
I’m a little overweight and my log book’s way behind
Nothing bothers me tonight
I can dodge all them scales all right
Six days on the road and now I’m gonna make it home tonight

On Wed, 28 Mar 2007 13:51:57 GMT, 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.

With about 375 hours in a Cherokee 180 and about 1200 in a straight
tail Beechcraft (Debonair) my take it this.

I like the 180 better than the Archer even though the Archer lookes
nicer with that taper wing and is a bit faster.

That constant cord, thick wing makes the 180 one of the most docile
airplanes you will find and it still has pretty good performance. Very
good climb and tremendous at getting into short fields with the steep
descent.

I can't see as a gallon or two over the range of the Cherokee, or
Archer is going to be worth worrying about....although we did have one
guy land ours with 1/2 gallon of fuel on board (all in one tank). He'd
flown the same trip (St Louis Mo to Midland, MI) so many times he
never paid any attention to the time and this time coming home he had
one bodatios head wind. (and a LOT OF LUCK!

Having flown Both the 180 and the Deb in torrential rain I can say I'd
much prefer a thicker windsheild to prettier wings. It was deafening!

As to fuel, we flew the 180 down to Muncie IN to pick up the Deb. My
friend took off well ahead of me, but I passed him before we reached
Ft Wayne. I was back in Midland, had the Deb put away in the hangar
and was having a cup of coffee in the terminal building when I head
him call in. When they filled the Cherokee up, I found I had used
less than one gallon more to cover the same route at close to 190 MPH.

I had to ferry the Deb up to HTL to have some work done on the gear
which meant leaving it down. Now that's using gas. The speed was
about the same as the Cherokee but burning about 14 1/2 GPH.

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

I'm glad you said most. I'm building a Glasair III and a high aspect
ratio it doesn't have. Wing span is a tad over 23' with a 4' wide
fuselage in the middle so that makes each wing about 9 1/2 feet long.
It also has almost 30# per square foot of wing loading on that tiny
wing but it sure does go. Built like a tank too. If you think the 180
has a steep descent you should fly a G-III once. :-)) Normal is about
2000 fpm power off.

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?

That's a diffiuclt question to answer because there are so many
variables. You could easily end up with a wing that could travel far
faster than the rest of the structure could handle. On the Cherokee
the landing gear presents a lot of drag. To maintain at least the
handleing characteristics of the Archer you probably ould not get much
faster than an Archer. To simply replace the wing with a composit one
of the same design would most likely make little difference.

All airplanes are a group of compromises. The 180 is the only plane
I've ever flown where I could put it into a full stall, hold the
elevator full up and still use the ailerons in turns. (with careful
application) Almost any changes are going to result in a plane that
is less forgiving. It's very difficult to hold the Deb in a stall
without having it drop a wing. It's like balancing on a tight rope and
if you touch an aileron to raise a wing, that wing will instead go
down (abruptly) and you will most likely roll into a spin.

Speed comes at a price.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

The composite construction makes a big difference in making
possible the use of supercritical airfoils. These airfoils need a
slick surface, so much so that flying in rain degrades their
performance to the point that they can become dangerous. You'd never
build a wing like that using sheet metal and rivets. Just the lap
joints or any waviness in the aluminum would cause trouble.
Composite looks nice, but I became allergic to some of that
stuff way back in the '70s. And in the cold winters here I've seen it
crack and delaminate. My preference is for something more resistant to
everyday life. Kinda like my old truck.

Dan