dc3 stall

[MikeSt]

I've read, and been told by a few pilots that the DC3 has very nasty stall characteristics. This apparently is the main reason to "wheel-land" the plane.

What makes the stall so evil in this plane?

Why was it designed that way? I'm guessing comprimises had to be made somewhere.

Mike

[Sparky Paul]

The first reason would be the large difference in chords, root to tip.
A second would be the sweepback.
A USN Test Pilot put a DC-3 thru the standard test procedures required today for certification, and it displayed 13 "safety of flight" discrepancies.
IOQ, it couldn't be certified today without some major changes.

[MikeSt]

Originally posted by Sparky Paul

A USN Test Pilot put a DC-3 thru the standard test procedures required today for certification, and it displayed 13 "safety of flight" discrepancies.
IOQ, it couldn't be certified today without some major changes.

So I guess aircraft design *has* progressed that much since it was designed ?

Or just faster computers ? :)

[Sparky Paul]

Things that weren't even considered in the middle 30's, such as cockpit vision, longitudinal and lateral stabilities..or control heaviness are now part of the FARs that a plane must meet to be acceptable.
DC-3s crash all the time around the world but so many were made it will be a long time before the last one goes.

[Ollie]

Mike,

When the DC-3 was designed, the first electronic computers using vacuum tubes were still a decade in the future. The application of electronic computers to aircraft configuration design was more than two decades after the design of the DC-3. In the mid 1930's sliderules, tables of logarithms and mechanical adding machines were the computational norm. The profession of aeronautical engineering was still in its infancy in the mid 30's. The transistor wasn't even invented until 1948.

[R2800]

My guess is that the human mind didn't measure up either. Or its all relative or something.
I flew the DC-3 in the fifties and thought it and I were pretty hot stuff.

Ignorance was bliss.:)

Maybe I'll change my name to "R1830" as atonement for the preceding remarks, as I recall if anyone said anything derogatory about them they could get cranky. Some kind of personality thing.:)

[surfimp]

FWIW, my grandfather flew DC-3s during WWII (India) and he believed they were the best airplanes ever built. That coming from a guy who had to fly them daily during the Indian monsoon season, where rapid altitude changes of 5,000 feet or more were not uncommon due to the radical up and down drafts associated with the thunderstorms. He also ferried one across the Atlantic from the U.S. to England in which, if I remember correctly, they had to take nearly everything out of the cabin in order to make room for a gigantic fuel tank. I believe they stopped in Greenland or Iceland--or both--on the way. Before flying C-47s (DC-3), he was an Army Air Corps flight instructor at Park's Air College outside St. Louis, and prior to the war he was giving air tours of the Wisconsin Dells in Piper Super Cruisers. He had around 7000 hours when he stopped keeping track, and probably another few thousand after that (or so I'm told). Even up to a couple years before he died, he could do a steep banked 360* turn in an Aviat Husky and not change altitude more than about 10 feet...from the back seat.

Just thought it might make for interesting commentary on the subject! :)

[Ollie]

The DC-3 ia a very tough aircraft structurally, even by today's standards and even considering that better materials are available today. One of the aspects of that ruggedness is the wing planform which favors a slightly smaller bending load on the wing spar than a wing with a wider tip chord. The DC-3 was designed to be economical at its cruising speed of about 180 MPH. This called for a limited twist in the wing that favored an efficient lift distribution at the coefficient of lift associated with the cruising speed. Optimizing the structural considerations and the efficiency considerations resulted in a plane that had to be landed with a generous stall margin for safety. You just can't optimize everything about a design because there are compromizes that are inescapable at any particular stage of the available technology. In this case, pilot skill and training can render a weak point almost irrelevant.

[MikeSt]

Ollie,

Originally posted by Ollie
Mike,
The profession of aeronautical engineering was still in its infancy in the mid 30's.

If a 25 passenger tail dragger radial engine was designed today, what would be the major differences ?

.. And don't say "it wouldn't be a taildgragger" :)

Mike

[R2800]

As much as I love twin round engined tail draggers why would anyone design one today? :)
Wouldn't it be twin turbo prop trike gear? And carry 40?
The airline bible says "keep the seat mile costs to a minimum"

[Sparky Paul]

Originally posted by Mike Stramba
Ollie,



If a 25 passenger tail dragger radial engine was designed today, what would be the major differences ?

.. And don't say "it wouldn't be a taildgragger" :)

Mike
.
Single engine? Not only NO, but....
Taildragger? Nope.
Radial engine?Nope.
.
It would be a variant on the Beech King Air today.

[Ollie]

First of all, I don't know of any radial engine aircraft in that size that are being designed today. Radials are out and turbo props are in for today's propeller driven designs. I suspect that the wings would be of composite construction with laminar flow airfoils. The wing area would be less than the DC-3 and flaps would be used to lower the landing and takeoff speeds. Multi engines would be employed for reliable one-engine-out capability. Fully retractable landing gear would be a feature. Cruising speed would probably be only a little short of 400 MPH. Stall speed would depend on the size of airfields the plane was designed to operate from. A lot would depend on the cargo load it was designed to carry in addition to passengers and the fuel it had to carry for the desired range.

Bert Rutan could give you a much better answer after he stopped laughing at the idea of a radial engine.

[MikeSt]

Just thinking "pretend".


Imagine a 1930''s engineer had access to today's knowledge, computers / software.

But still had to use the materials / engines of the time.

What might they have done differently?

Also, when did the switch to tricycle-gear happen?

[Ollie]

They would have used the laminar flow airfoils like those that improved the speed and range of the P51 and made it the best fighter of WWII. They would have used large spinners to reduce the drag of the radial engines without degrading the air cooling. They would have used constant speed (variable pitch ) props. They would have used completely enclosed retractable landing gear. They would have used flaps to allow low takeoff and landing speeds with less wing area. The reduced wing area would result in lower drag at cruising speed for lower fuel consumption and longer range. They would have used all metal rudders and elevators instead of fabric covered.

With the information available now they could even have designed a safer version of Northrop's flying wing and piloted it more safely. This configuration has inherent structural, payload carrying and fuel consumption advantages over conventional configurations. However, it has no tail to drag either on the ground or in the air. An inherent disadvantage would be longer span and its affect on ground handling and airport facilities.

Tricycle gear came into vogue just before and during the second world war. Examples are the B24, the P38 and the P39.