Props

[LCADolby]

I thought this would have led onto Prop designs. Very little is said anywhere about the different prop designs, like Paddle style props etc,

[earl1937]

When the wing is at the top, like a C-130 and other transports.  Then the weight of the fuselage CG below the wing acts like a pendulum to give a correction force to level out the plane.  (I think.)

Not being a design engineer, but I would think that dihedral is for stability purposes only. As far as top or bottom wing, I would think the design profile for the missions intended for that aircraft would have some inference on that. For example, look at the three aircraft below and think about the C-130 with a bottom wing, or the B-24 with a bottom wing:






I would guess that the viscount would have been a little faster and carry more passengers, but he length of the props, because of the bottom mounted wing, would not allow for more diameter props than what is on it.

As far as the C-130, it was designed as a multie  purpose cargo aircraft which could land and takeoff from unimproved runways and to have the most effective length prop, design dictate that a high wing be installed, and I am sure that clearance from the ground for the props also had something to do with the design.

As far as the B-24, again, where the wing was mounted was a matter of "mission profile" for that aircraft.

The fuseledge has really nothing to do with stability of the aircraft, it is more a wing design and vertical stabilizer thing as far as stability is concerned.

[715]

A dihedral on the wing creates a natural tendency of the airplane to right itself to level from a slight upset.  If a plane with dihedral rolls to the left slightly the left wings lift vector is directly perpendicular to gravity while the right wings lift vector is off axis from gravity.  This unbalanced lift vector (i.e. not exactly countering gravity) creates a side-slip force which creates a higher angle of attack on the lower wing (left in this case) which means higher lift on that side and a compensating roll to the right.

A high wing plane may not need dihedral because if it rolls to the left the weight of the fuselage is like a pendulum pushed to the right which means it wants to move back left (to vertical) which makes the plane roll right.  If the wing is on the centerline, or below the centerline the pendulum effect doesn't create a natural corrective force so the plane needs dihedral.

But then I'm not an aero-engineer, I just read Wikipedia     http://en.wikipedia.org/wiki/Dihedral_(aircraft) and "Fundamentals of Flight" 2nd ed., Shevell, p 317.

[morfiend]

Not being a design engineer, but I would think that dihedral is for stability purposes only. As far as top or bottom wing, I would think the design profile for the missions intended for that aircraft would have some inference on that. For example, look at the three aircraft below and think about the C-130 with a bottom wing, or the B-24 with a bottom wing:
(Image removed from quote.)

(Image removed from quote.)

(Image removed from quote.)

I would guess that the viscount would have been a little faster and carry more passengers, but he length of the props, because of the bottom mounted wing, would not allow for more diameter props than what is on it.

As far as the C-130, it was designed as a multie  purpose cargo aircraft which could land and takeoff from unimproved runways and to have the most effective length prop, design dictate that a high wing be installed, and I am sure that clearance from the ground for the props also had something to do with the design.

As far as the B-24, again, where the wing was mounted was a matter of "mission profile" for that aircraft.

The fuseledge has really nothing to do with stability of the aircraft, it is more a wing design and vertical stabilizer thing as far as stability is concerned.

  Earl, I thought that was a viscount!    It's the first plane I flew in,I was all of 5 or 6 at the time and sat right over the wing,looks like the third window back in your pic.!



     

[earl1937]

  Earl, I thought that was a viscount!    It's the first plane I flew in,I was all of 5 or 6 at the time and sat right over the wing,looks like the third window back in your pic.!



     

I used to see a lot of them back in the 60's, I think it was. Captail airlines had serveral of them, but can't remember who else were using them. Was a pretty good aircraft from all I ever heard about them.

[GScholz]

The primary reason for the C-130's high wing is to get the cargo hold as close to the ground as possible for easier loading/unloading. The first aircraft designed around this concept was the Me 323 Gigant.



Curiously it also has a fair amount of dihedral.

[colmbo]

Even high-wing aircraft have dihedral, on a Cessna it's 1.5 degrees if memory serves me correctly.

Some dihedral effect can also come from the taper in wing thickness.  Notice the B-24 photo -- top surface of the wing is almost parallel to ground while the bottom surface, due to thickness taper, slopes upward toward the tip providing some dihedral/dihedral effect.

B-24 wing position more likely because it is an adaptation of a 2 engine seaplane design that Consolidated had on the board when they took up the B-24 project. This is the same reason it has the twin tails (keeps a rudder in the prop blast for improved control on the water).  The design work was already done in those areas, no need to reinvent them.

[Widewing]

The primary reason for the C-130's high wing is to get the cargo hold as close to the ground as possible for easier loading/unloading. The first aircraft designed around this concept was the Me 323 Gigant.

(Image removed from quote.)

Curiously it also has a fair amount of dihedral.

I believe that the Ar 232 predated the Gigant, and probably was the first "modern" cargo plane design, with the basic elements that are considered standard design fare these days...

[GScholz]

Arguably. Both entered service about the same time, although the Me flew much earlier as the unpowered 321 assault glider. The Arado is a beautiful aircraft for sure, and received high praise from Eric Brown after the war. The British also used a few captured examples in operational service with the RAF.