Pics that make you smile

[Dashmellow]

how many have you tried in your turbo prop?

seriously though without knowing more about the origins of the pic and the circumstances it was created under it's a bit hard to even guess

No, but the camera did a better job with the difficult exposure scenario and image quality than any dash cam I've seen even without the propeller blade question.

 

[jokiin]

No, but the camera did a better job with the difficult exposure scenario and image quality than any dash cam I've seen even without the propeller blade question.

as it should, it has much higher spec, ironically iPhones make for pretty poor dashcams

 

[ryanprins]

iPhone captures turbo-prop. (In tricky lighting )
(When will dash cams be able to do this? )
View attachment 32236

Zoom in on the photo. Im not incredibly familiar with all the instruments but it would appear to me that this plane is on the ground in heavy fog and the guy on the left is just pushing the throttle up to begin taxiing for takeoff.
I could be wrong but if i am i would say the most likely scenario is its photoshopped. Shutterspeed and all that on an iphone is pretty straightforeward and if you hold the phone still and take a picture of something moving very quickly in front of you it blurrs if your shutterspeed is too slow.
All guesses here but you said 14,000rpm. Lets guess a 6ft dia propeller (probably bigger?)
The tip of the prop is travelling 366.5 inches per second. There is maybe 1 inch of blurr. So shutter speed is 1/366 of a second.
I find it doubtful that the shutterspeed was that high unless there is an app that lets you control everything about the camera and they took the picture dark and artificially brightened it after. The depth of field isnt too bad so its not like they had a big apeture.

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[Dashmellow]

as it should, it has much higher spec, ironically iPhones make for pretty poor dashcams

All smartphones make for poor dash cams.

Just recently I saw the iPhone on a list of current best smartphone cameras. They've been doing some innovative stuff recently.

 

[Dashmellow]

Zoom in on the photo. Im not incredibly familiar with all the instruments but it would appear to me that this plane is on the ground in heavy fog and the guy on the left is just pushing the throttle up to begin taxiing for takeoff.
I could be wrong but if i am i would say the most likely scenario is its photoshopped. Shutterspeed and all that on an iphone is pretty straightforeward and if you hold the phone still and take a picture of something moving very quickly in front of you it blurrs if your shutterspeed is too slow.
All guesses here but you said 14,000rpm. Lets guess a 6ft dia propeller (probably bigger?)
The tip of the prop is travelling 366.5 inches per second. There is maybe 1 inch of blurr. So shutter speed is 1/366 of a second.
I find it doubtful that the shutterspeed was that high unless there is an app that lets you control everything about the camera and they took the picture dark and artificially brightened it after. The depth of field isnt too bad so its not like they had a big apeture.

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I happen to know who took the photo and I can assure you it is not Photoshopped. I believe the actual turbo-prop speed is 13,800 rpm, I agree that the shutter speed is not that high but that would not likely be the shutter speed the camera would chose to capture a dim interior that takes up 3/4ths of the frame. That's what really stood out to me about the photo.

 

[jokiin]

Now that you know who took this perhaps you can check if it's a photo or a frame grab from video

 

[Dashmellow]

Now that you know who took this perhaps you can check if it's a photo or a frame grab from video

It was on a Twitter feed, from someone I have not had contact with for a time, (but someone who doesn't know from Photoshop) but I'll see.

 

[kuoh]

The artificial horizon is indicating a fairly noticeable bank angle, certainly much more than what I think would be normal on a typical runway. The lines in the clouds also appear to correlate with the angle shown. Can't quite make out the altitude, airspeed or other gauges from my phone screen though.

KuoH

Zoom in on the photo. Im not incredibly familiar with all the instruments but it would appear to me that this plane is on the ground in heavy fog and the guy on the left is just pushing the throttle up to begin taxiing for takeoff.

 

[Dashmellow]

BTW, a while back Apple purchased LinX Imaging and some of their array technology has now made its way into the dual lens iPhone 7. That could explain the quality of the image capture.

 

[kamkar]

Wasent there someone that used a pooload of smartphone camera modules to make huge resolution pictures, i seem to remember something in those lines.

 

[jokiin]

Wasent there someone that used a pooload of smartphone camera modules to make huge resolution pictures, i seem to remember something in those lines.

Yep, they used each sensor as one pixel in the array

 

[DT MI]

...I believe the actual turbo-prop speed is 13,800 rpm....

I'm pretty sure that's the rotation speed of the turbine itself and not the prop.

The turbine shaft is connect the the prop via a reduction gear, generally about a 10:1 to 15:1 reduction ratio. This is done for two primary reasons: 1) convert the high speed, low torque output of the turbine to a high torque, lower speed for the prop and 2) insure the tips of the prop stay subsonic for efficiency, safety and noise reduction reasons.

 

[Dashmellow]

I'm pretty sure that's the rotation speed of the turbine itself and not the prop.

The turbine shaft is connect the the prop via a reduction gear, generally about a 10:1 to 15:1 reduction ratio. This is done for two primary reasons: 1) convert the high speed, low torque output of the turbine to a high torque, lower speed for the prop and 2) insure the tips of the prop stay subsonic for efficiency, safety and noise reduction reasons.

I think you're probably right. I'm not an expert on turbo-props. I just looked up the basic rpm specs.

 

[DT MI]

...I'm not an expert on turbo-props....

Nor am I. Just stuff I pick up hanging around people who know more about such things than I do - which is generally most anybody that knows anything.

 

[SawMaster]

I believe the actual turbo-prop speed is 13,800 rpm,

I think you're mistaking engine RPM for prop speed, which will be much lower. In fact it wont be much more than a normally aspirated prop would be with a similar blade diameter.

The limiting factor for a prop to work effectively is that it has to remain sub-sonic at the blade tips, and a normally aspirated engine can easily exceed that point. What makes turbo-props faster in flight is that they can use more blade pitch, wider blades, and a smaller blade diameter (for lower blade tip speeds) which produces more thrust because the engine now has the extra power to handle that, especially at higher altitudes where the turbine engine is more efficient. There is a gearbox between engine and prop to slow the blade speed down and that also multiplies the available torque to turn the prop with

Please remain seated until the airplane discussion comes to a complete stop and the "No Camera Discussion" light goes out. And as always, thank you for flying DCT

Phil

 

[Dashmellow]

I think you're mistaking engine RPM for prop speed, which will be much lower. In fact it wont be much more than a normally aspirated prop would be with a similar blade diameter.

The limiting factor for a prop to work effectively is that it has to remain sub-sonic at the blade tips, and a normally aspirated engine can easily exceed that point. What makes turbo-props faster in flight is that they can use more blade pitch, wider blades, and a smaller blade diameter (for lower blade tip speeds) which produces more thrust because the engine now has the extra power to handle that, especially at higher altitudes where the turbine engine is more efficient. There is a gearbox between engine and prop to slow the blade speed down and that also multiplies the available torque to turn the prop with

Please remain seated until the airplane discussion comes to a complete stop and the "No Camera Discussion" light goes out. And as always, thank you for flying DCT

Phil

As I said to @DT MI above, just before your post, "I think you're probably right. I'm not an expert on turbo-props."

 

[SawMaster]

You beat me to posting My notoriously slow typing and need for numerous error-fixes makes my posts lag quite a bit. And this time there wasn't the usual pop-up about new posts to keep me up-to-speed

Phil

 

[kamkar]

insure the tips of the prop stay subsonic for efficiency, safety and noise reduction reasons.

A problem the Russians dident bother to think about with their TU-95 Bear bombers, if you have good hearing you can hear them here in Denmark as they pass over Greenland.

"Each of the Bear’s eight four-blade propellers break the sound barrier as they turn, making the Tu-95 perhaps the loudest plane on the planet. In fact, Bears are so noisy that they can be detected by U.S. underwater sonar sensors and submarines. Fighter pilots sent up to intercept Bears have reported that the planes’ unmistakable drone can even be heard over the sound of their own jets."

 

[SawMaster]

The US B-36 was much like that too. "Six turning and four burning" One of my Ham friends flew in those

Phil

 

[rusty503]

Actually the aircraft is doing about 120 knots at around 600 ft or meters altitude. What you think is fog looks more like clouds. Most likely this was taken during takeoff.

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