All Things Aviation Related

[Heel n Toe]

[dlockhart]

[hbueno]

I think I'm appalled, but not quite sure. Pilot crashes his plane 7 times in 7 days.

https://www.record-eagle.com/news/seawind-saga-pilot-who-crashed-in-lake-michigan-had-7-crashes-in-7-days/article_867676c0-e8d7-11eb-be82-db592d516d36.html

[fanaudical]

Some impressive flying here (sorry - video can't be embedded):

https://youtu.be/To-xsGHm3C8

[Fast Freddy 944]

....

[pmax]

http://forums.pelicanparts.com/off-topic-discussions/1104228-stuck-seatac-airport-southwest-airlines.html

Let's see if anyone here knows.

[daepp]

Yeah, Southwest et al. - sickout or weather? Conspiracy?

[Jolly Amaranto]

They are trying to keep too many flights going using minimum staff/personnel. They can't hire enough people fast enough from pilots to baggage apes. If any little glitch comes along, be it weather, sickout, burnout or ATC and the house of cards collapses.

[Fast Freddy 944]

I bet if it was 2018, all systems would be running up to snuff, not anymore. Good luck flying on an unproven electric or solar powered airplane. LOL!

[Heel n Toe]

[pavulon]

[flipper35]

Side slip, I will show you side slip!

[edgemar]

What do more blades on the propeller do for performance?

[Seahawk]

Originally Posted by edgemar

What do more blades on the propeller do for performance?

The Bronco...which I have flown in, is an amazing vehicle.

I know you are going to hate the answer, but it is that it depends

BTW, it is not just the propeller, it is the whole aircraft integration...vibration, spool up time, performance requirements (aggressive or cruise flight) type of propeller integration at the hub, on and on.

I am guessing that the Bronco's new prop is mated to an engine that can handle the torque and get the aircraft out of where they want it.

That may be the only aircraft I have flown I'd love to fly again.

[Dantilla]

Originally Posted by edgemar

What do more blades on the propeller do for performance?

They can absorb more power, converting it to thrust.

A larger-diameter two-blade prop would be more efficient, except for two issues:

1) The prop must have adequate ground clearance.
Not an issue for the Bronco, but also need clearance from the fuselage.
Moving the engines outboard to allow larger props also creates unacceptable asymmetric thrust if one engine is inoperative.

2) If the tips of the prop exceed mach 1, efficiency suffers dramatically.
-Also, if the tips exceed mach 1, the noise level increases tremendously.

This is why the typical light airplane uses a large displacement, direct drive engine that redlines around 2700 rpm or so. A six foot diameter prop at 2700 rpm is just below supersonic tip speeds.

[bugstrider]

This is a video of the plane that crashed near Sacramento. Everyone survived but it’s still bad.

https://youtu.be/dOuWiYhzMSE

https://www.kcra.com/article/plane-down-wilton-sacramento-county/37966377

[john70t]

Originally Posted by Dantilla

They can absorb more power, converting it to thrust.

To my understanding the wider blades grab more air but also create more drag even when pitched.

There are trade-offs to everything.
-The engine only produces so much rpm and torque inside an optimised fuel-efficiency gph target.
-The airframe is designed for low heavy cargo and slow torque conditions vs. sleek speed and high altitudes.
-2 wide straight paddles versus 5 spiral type propellers will result in entirely different results. There's definitely an applied science in effect when they design them.

[BReif61]

Originally Posted by Dantilla

(snip)

A larger-diameter two-blade prop would be more efficient, except for two issues:

(snip)

Isn't the most aerodynamically efficient propeller a counter-weighted single blade? Which obviously has its own drawbacks.

[svandamme]

Originally Posted by edgemar

What do more blades on the propeller do for performance?

- They can apply more engine power for a smaller diameter prop
packaging is more compact
- Less stress on the prop blades if shorter diameter (less centrifugal force on the blade just from spinning and lower velocities at the tips)
- velocity at the tips lower, and prevent them from going supersonic, which is bad for noise abation near airports.
- They are better at higher altitudes and lower air density, at speed.. because well, more blades for less air move same amount of air as less blades in denser air


That's just me guessing, there may be other aspects

I don't think aerodynamic performance is much of a difference on a moving plane.. it's not going to be cavitating in air from the previous blade anyway if the plane is moving at 150 knots.

[Seahawk]

Originally Posted by BReif61

Isn't the most aerodynamically efficient propeller a counter-weighted single blade? Which obviously has its own drawbacks.

My partner designs blades for different industries - aircraft, UAS, even Chicken Houses.

Michigan Aero undergrad, Stanford MS in Aero. We chatted a few minutes ago in preparation for a 0830 meeting with our folks.

His answer: "It depends."

He is going to send me some links later.

The chicken house design efforts center around cooling fans for the large houses. They want maximum efficiency across a fairly wide temperature range and air flows. Electricity is the number one cost for the chicken industry.

We do the design work for the largest supplier of fans in the USA.