Jimmy T Loc: Virginia

Good discussion and Great PP on the pic, Wow!
Best Wishes
Jimmy T Sends

profbowman Loc: Harrisonburg, VA, USA

Howard, I did see what you were trying to get us to see. However, as others noted it looks like either camera motion or subject (plane) movement. To authenticate your observation, I cropped the plane out of the three photos and stringed them together vertically. Apart from the bolts/rivets, all three images look similar. In the second string of cropped images, I reduced the size by half on each side and tried some sharpening. All three look even more alike.

Back to the movement of the rivets, I did some calculations. I do not know the size of the radio-controlled model plane nor its speed, so I made these assumptions. Let's guess that the plane is 6 ft (2 m) long and is moving about 30 mi/hr (48 km/hr).

This speed turns out to be 528 in/s (1 340 cm/s)/. Since the shutter speed was 1/1000 s, this means the plane would have moved about 0.5 in during the picture taking
With an estimated length of 6 ft or 72 in (182 cm), yhis translates into the plane moving about 7 1/3 plane lengths per second.

To me the idea that at this speed, the streak of the rivet could be about 0.5 in (1.3 cm), makes sense. as I compared it to the total length of the plane.

If these calculations make sense, then the plane's motion could account for most of the streak on the photo, and therefore even a slight motion of the hand in panning could make the streak to be forward or backwards.

Does this make sense? --Richard

If this image does not display at 100%, it may be difficult to observe the streaks.

(Download)

At 100% display, this photo should take up only 25% of what the first cropped images do.

(Download)

alberio Loc: Casa Grande AZ

Optical delusion, maybe 🙃🙂🙃

Boomer Jim Loc: Newcastle Okla

It looks like a little bit of blur distorting the vents.

flyboy61 Loc: The Great American Desert

#3 appears to be sharpest to me, but the other photos (looking at the side vents) don't appear unusual, just a little unsharp.

flyboy61 Loc: The Great American Desert

jrvinson45 Loc: Buckeye, AZ

Seems as if you are all trying to assign the answer to a photography phenomenon when in reality it’s just as likely to be an internal combustion radial engine phenomenon simplistically categorized as harmonic vibration. I haven’t the foggiest idea how many cylinders this beauty has; nor do I know how many rpm’s it’s turning at this point in its’ descent; however, it is probably humming like a rotary saw and in each of the images the camera has captured evidence of engine vibration at different instances of a power stroke at a different point on different individual cylinders. The most perfect panning won’t stop the blurring and vibration being captured at these shutter speeds… of course that’s just my opinion… I could be wrong.🤡. Awesom shots, by the way👍👍👍!

WILLARD98407 Loc: TACOMA, WA.

Just my . 25 cents worth -
I have observed in MY use of bursting (being more unsteady than when I was younger) upon pressing the shutter button to start the burst, some camera motion is introduced.
This usually calms down by the 3rd or 4th exposure and one of those two will be my sharpest.
May not be the case here, but when the camera motion changes direction in that short amount of time and then is so much less on the third exposure, it makes me suspicious that it may be caused by the same thing I observe in my own efforts.
Hadn't seen anyone bring up this possibility, so I thought I'd throw it into the mix.

Howard5252 Loc: New York / Florida (now)

Thank you to all who took the time to respond.