If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#141
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
"Paul Tomblin" wrote The danger of that is that his blatant misconceptions could get somebody killed if not challenged. A boilerplate response such as what Mortimer was doing would take care of that. Besides, I think the chances of anyone showing up and not catching on to what is happening is pretty slim. He is so far off base as to be ridiculous. Plus, most of what he responds to is off topic, anyway, so no danger there. I'll do the boilerplate statement, if everyone would quit their MXed habit. Anything, to make it all stop. -- Jim in NC |
#142
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
On Dec 5, 2:05 pm, wrote:
In rec.aviation.piloting Harry K wrote: On Dec 4, 8:25 pm, wrote: In rec.aviation.piloting Harry K wrote: snip Harry K- Hide quoted text - - Show quoted text - After thinking that over... It gets worse. There will be multiple rpm that will show the effect under strobe conditions. With a 2 blade prop it can be sychronizing every 1/2 rev. 3-blade prop every 1/3 or 2/3 rev, etc. in addition to synching on the harmonics. It isn't that bad. Synchronization only occurs on integral fractions and engine RPM is usually 1000 and about 2700 RPM so the possibilities are limited. For a 2 bladed prop: 7200/2= 3600 - 1800 RPM 7200/3= 2400 - 2400 RPM and 1200 RPM 7200/4= 1800 - 1800 RPM and 900 RPM etc. I leave it to someone else to show how many blades you see at each RPM. -- Jim Pennino Since the prop appears stationary, you would see all the blades. Yes, but how many virtual blades will you see? Simple example: You are illuminating a 2 bladed prop running at 1000 RPM with a strobe light pulsing at 4000 pulses per minute. In the time between pulses, the prop makes 1/4 of a turn. The prop is therefor lite up every 1/4 turn and it appears as though the prop has 4 blades. -- Jim Pennino Remove .spam.sux to reply.- Hide quoted text - - Show quoted text - Nope. The prop appears stationary and you see only the two. What you see is the complete image (frame), not a composite of 4 'frames'. I'm talking about eyeballs and strobed light here, there are no "images" or "frames" involved. What you see is a prop blade in whatever position it is in when the light goes off. If the light is going off every quarter turn, you see a particular blade end in four different places each a quarter turn apart. If the light is going off every sixth of a turn, you see a particular blade end in six different places each a sixth of a turn apart. -- Jim Pennino Remove .spam.sux to reply.- Hide quoted text - - Show quoted text - Yes, but you will see them (along with all the others) one at a time. Not the entire sequence at once or even a composite. It is the same as taking a snap shot with shutter speed fast enough to stop the motion, it will show all blades, in this case it will show two blades and no 'virtual' blades. You can prove it with a fan and a variable strobe light but I suspect that will not be a common kitchen appliance . Harry K |
#143
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
On Dec 5, 9:38 am, Mxsmanic wrote:
Harry K writes: Nope. The prop appears stationary and you see only the two. What you see is the complete image (frame), not a composite of 4 'frames'. You are both incorrect. It snowed here last night. Harry K |
#144
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
cavelamb himself wrote:
Yes - I have a name wrote: "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message ... Shut the **** up, MX. So Say We All! So, which way is the naked lady spinning? http://www.sonnyradio.com/spinninglady.html The reflection of her raised leg on the floor lasts only half a turn, moving from right to left. The leg is farther from the viewer during that time, and there's not enough floor space in front of her to reflect the leg when it's up close. So she's going CCW. But I will *continue* to study this. |
#145
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
|
#146
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
|
#147
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
In article
, Harry K wrote: On Dec 5, 2:05 pm, wrote: In rec.aviation.piloting Harry K wrote: On Dec 4, 8:25 pm, wrote: In rec.aviation.piloting Harry K wrote: snip Harry K- Hide quoted text - - Show quoted text - After thinking that over... It gets worse. There will be multiple rpm that will show the effect under strobe conditions. With a 2 blade prop it can be sychronizing every 1/2 rev. 3-blade prop every 1/3 or 2/3 rev, etc. in addition to synching on the harmonics. It isn't that bad. Synchronization only occurs on integral fractions and engine RPM is usually 1000 and about 2700 RPM so the possibilities are limited. For a 2 bladed prop: 7200/2= 3600 - 1800 RPM 7200/3= 2400 - 2400 RPM and 1200 RPM 7200/4= 1800 - 1800 RPM and 900 RPM etc. I leave it to someone else to show how many blades you see at each RPM. -- Jim Pennino Since the prop appears stationary, you would see all the blades. Yes, but how many virtual blades will you see? Simple example: You are illuminating a 2 bladed prop running at 1000 RPM with a strobe light pulsing at 4000 pulses per minute. In the time between pulses, the prop makes 1/4 of a turn. The prop is therefor lite up every 1/4 turn and it appears as though the prop has 4 blades. -- Jim Pennino Remove .spam.sux to reply.- Hide quoted text - - Show quoted text - Nope. The prop appears stationary and you see only the two. What you see is the complete image (frame), not a composite of 4 'frames'. I'm talking about eyeballs and strobed light here, there are no "images" or "frames" involved. What you see is a prop blade in whatever position it is in when the light goes off. If the light is going off every quarter turn, you see a particular blade end in four different places each a quarter turn apart. If the light is going off every sixth of a turn, you see a particular blade end in six different places each a sixth of a turn apart. -- Jim Pennino Remove .spam.sux to reply.- Hide quoted text - - Show quoted text - Yes, but you will see them (along with all the others) one at a time. Not the entire sequence at once or even a composite. It is the same as taking a snap shot with shutter speed fast enough to stop the motion, it will show all blades, in this case it will show two blades and no 'virtual' blades. You can prove it with a fan and a variable strobe light but I suspect that will not be a common kitchen appliance . Harry K You are apparently unacquainted with the phenomenon known as "persistence of vision". Look it up. -- Alan Baker Vancouver, British Columbia "If you raise the ceiling four feet, move the fireplace from that wall to that wall, you'll still only get the full stereophonic effect if you sit in the bottom of that cupboard." |
#148
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
In rec.aviation.piloting Harry K wrote:
On Dec 5, 2:05 pm, wrote: What you see is a prop blade in whatever position it is in when the light goes off. If the light is going off every quarter turn, you see a particular blade end in four different places each a quarter turn apart. If the light is going off every sixth of a turn, you see a particular blade end in six different places each a sixth of a turn apart. -- Jim Pennino Remove .spam.sux to reply.- Hide quoted text - - Show quoted text - Yes, but you will see them (along with all the others) one at a time. Not the entire sequence at once or even a composite. It is the same as taking a snap shot with shutter speed fast enough to stop the motion, it will show all blades, in this case it will show two blades and no 'virtual' blades. You can prove it with a fan and a variable strobe light but I suspect that will not be a common kitchen appliance . Um, no. Assuming everything is synchronous, you will see what appears to be multiple blades because of eye persistence, the same reason movies appear to smoothly move. It is the same as taking snap shots with shutter speed fast enough to stop the motion, and taking an integral number of snap shots during the rotation. Take one snap shot when the blade tip is straight up, take the next when the blade has moved 90 degrees, the next when the blade has moved another 90 degees, take the last when the blade has moved another 90 degrees. Make slides of the pictures and put them on top of each other to simulate eye persistence. Replace "take the snap shot" with "flash the strobe". You can prove it with a fan and a variable strobe light. -- Jim Pennino Remove .spam.sux to reply. |
#149
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
On 12/3/2007 8:32 PM Mxsmanic ignored two million years of human
evolution to write: At any given moment there are thousands of aircraft powered by turbofans in flight. At any given moment, you're a total dip****. You also lie a lot. -- dgs |
#150
|
|||
|
|||
Spinner strobing as a "Bird Strike Countermeasure"
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Spinner strobing as a "Bird Strike Countermeasure" | Jim Logajan | Piloting | 259 | December 13th 07 05:43 AM |
Saturday 072807 in Oshkosh Pt 6 - Warbird show pix I forgot to post earlier [10/33] - "Bird Dog.jpg" yEnc (1/1) | Just Plane Noise[_2_] | Aviation Photos | 0 | July 31st 07 10:48 PM |
"British trace missile in copter strike to Iran" | Mike[_7_] | Naval Aviation | 8 | March 10th 07 08:20 PM |
Bird strike | Bob Chilcoat | Piloting | 5 | September 6th 05 07:05 AM |
Bird strike | Jase Vanover | Piloting | 16 | May 17th 05 11:44 AM |