Props

[earl1937]

  Props come in all kinds of shapes and sizes! During WW2, there were 2 basic types of props, a "Tractor Prop" and a "Pusher Prop". Name some famous aircraft which used these two props as standard equipment.

[BuckShot]

Cessna skymaster, b-36, Lakes amphibian

[Karnak]

Do335

[earl1937]

Cessna skymaster, b-36, Lakes amphibian

They are powered by pusher props, but did not fly in WW2

[Baggy]

Supermarine Walrus - Read the OP again so I'm wrong - pusher only!

[morfiend]

 Several of the german flying boats used both pusher and tractor props!




   

[save]

Saab A21
1943 plane, one of the first with eject seat.

[Widewing]

Dornier built several aircraft that had both pusher and tractor props/engines.

These include the Dornier Do J Wal (Do 16), Do 18, Do 26 and the Do 335.

[GScholz]

Dornier X, 1929

http://www.youtube.com/watch?v=v2aaXfqxFrQ

12 engines in pull-push configuration. 123,000 lbs, 170 passengers.

[GScholz]

... It kind of was the Spruce Goose of the '30s. Not very much more successful either with only three built, and no real commercial use.

[Brooke]

Dornier X, 1929

http://www.youtube.com/watch?v=v2aaXfqxFrQ

12 engines in pull-push configuration. 123,000 lbs, 170 passengers.

That is really cool! 

[bustr]

When does an aircraft not need dihedral?

[715]

When does an aircraft not need dihedral?

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.)

[Mace2004]

When does an aircraft not need dihedral?

Depends on whether you're talking about dihedral angle or dihedral effect.  All airplanes should have positive dihedral effect if you want it to be stable but if it's angle you're talking about then it doesn't need it when it doesn't need it, i.e., when sufficient dihedral effect occurs without dihedral angle due to things like the sweep and/size/position of its wings and CG.  If the plane has insufficient dihedral effect then dihedral angle can be added.  If it has too much dihedral effect then the designer can use anhedral angle.  Of course, you can even do both and have polyhedral  angles.  The F-4U has a lot of dihedral on the outer wings to make up for the large amount of anhedral on the inner wing.  The F-4 Phantom is also an oddball with dihedral angle on the wing tips and anhedral angle on the horizontal stabs.  715 is sorta correct but incomplete.  GA airplanes like the Cessna 172 prize stability over maneuverability and inexpensive construction over expensive construction but most airplanes with top mounted wings usually have anhedral angle to reduce the dihedral effect.  On the other hand, anhedral angle is seen even with many planes with mid-mounted wings like the F105 and X-15.  It all depends on what flight characteristics you need.

[Charge]

"The F-4 Phantom is also an oddball with dihedral angle on the wing tips and anhedral angle on the horizontal stabs."

Ahhh, my all time favorite. The anhedral on hz stabs was not there initially but at prototype stage they noticed that the main wing blanketed the hz stab reducing the effectiveness badly, so the anhedral was put in to  get the stab to stay in effective airflow.

-C+