What did you fly in today?

[Dave W]

I'm on the Flybe Embraer 195 again .Travelling from Glasgow to my home in Southend .[ATTACH]291035[/ATTACH]

[rickoshea52]

My ride last Friday now tucked up in the hangar alongside me.

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[Dave W]

Flew to Glasgow from Southend on this ATR72-600 this afternoon. It was a replacement for the usual Embraer 195[ATTACH]294434[/ATTACH]

[flyjoe180]

Been out and about again...[ATTACH]294989[/ATTACH]

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[rickoshea52]

Off to Dayton OH via Chicago. Really excited to visit the USAF museum this weekend.

[colin m]

Flew to Glasgow from Southend on this ATR72-600 this afternoon. It was a replacement for the usual Embraer 195[ATTACH]294434[/ATTACH]

Dave, explain those 'bent' propeller blades would you, are they much more efficient than 'typical' straight blades ? Assuming that efficiency is the reason behind them.

[flyjoe180]

Dave, explain those 'bent' propeller blades would you, are they much more efficient than 'typical' straight blades ? Assuming that efficiency is the reason behind them.

Colin, from my memory banks it's to do with wave drag reduction. Wave drag is the sudden increase in drag caused by compression of the air in front of an object about to break the speed of sound (subsonic to supersonic).

In the ATR's case, six blades instead of the ATR's original four on the earlier version, are fitted for power absorption. Turboprops utilise the efficiency and power of turbine engines to drive a propeller. Unlike jets, propeller driven aircraft suffer from serious issues at higher speeds (jets suffer at the slower end of the scale). The tip of a propeller blade can easily reach the speed of sound (think of a Texan/Harvard, that raspy sound is the compression of air at the prop tips). Exceeding the speed of sound causes loss of lift (thrust in this case) due to a massive wave drag increase. The onset of the speed of sound can be delayed by sweeping the leading edge aft of the relative airflow (the same reason for a swept wing on a jet). This means a propeller blade can spin faster and retain efficiency over a larger area of the blade for longer, delaying the speed of sound (critical Mach number for those interested), allowing for a higher cruise speed. Hence the 'scimitar' shaped blades on the ATR in Dave's picture.

Not that anyone in an ATR would ever notice...

[Dave W]

Thanks for that Joe. I studdied propellers for my license many years ago. Ive never worked on them and cant remember much about them!.

[rickoshea52]

Back on a CRJ for the first time in ages.

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[colin m]

Colin, from my memory banks it's to do with wave drag reduction. Wave drag is the sudden increase in drag caused by compression of the air in front of an object about to break the speed of sound (subsonic to supersonic).

In the ATR's case, six blades instead of the ATR's original four on the earlier version, are fitted for power absorption. Turboprops utilise the efficiency and power of turbine engines to drive a propeller. Unlike jets, propeller driven aircraft suffer from serious issues at higher speeds (jets suffer at the slower end of the scale). The tip of a propeller blade can easily reach the speed of sound (think of a Texan/Harvard, that raspy sound is the compression of air at the prop tips). Exceeding the speed of sound causes loss of lift (thrust in this case) due to a massive wave drag increase. The onset of the speed of sound can be delayed by sweeping the leading edge aft of the relative airflow (the same reason for a swept wing on a jet). This means a propeller blade can spin faster and retain efficiency over a larger area of the blade for longer, delaying the speed of sound (critical Mach number for those interested), allowing for a higher cruise speed. Hence the 'scimitar' shaped blades on the ATR in Dave's picture.

Not that anyone in an ATR would ever notice...

That's brilliant Joe. I had to read your explanation twice to get it all in, but yes, I understand, thank you. I've seen a few old films about flying experiments and pilots trying to break the sound barrier. So I imagine 'wave drag' was the problem they were trying to overcome, but of course at the time, didn't know what the problem was.

[rickoshea52]

Dreamliner to Toronto...I like the mask on the cockpit windscreen.

[Dave W]

Embraer 195 to Glasgow again.

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[flyjoe180]

Electrical storms and no one's best mate, Saint Elmo. My windshield a few weeks back.

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That arcing is continuous, the fuzzy blob at the bottom is St Elmo's fire, dancing around and up and down the windsheld wiper. Tried to video it but the camera wasn't up to it and I was a bit busy.

[yak face]

Jeez joe that looks mildly terrifying to someone who doesnt see it all the time like you do!

[flyjoe180]

Jeez joe that looks mildly terrifying to someone who doesnt see it all the time like you do!

It's one of those phenomenon that you rarely see in the back, purely a consequence of flying through electrically-charged air at high speed. Thought it might be of interest. We've had a lot of electrical storms lately.