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View Full Version : Structural Integrity of a Pigeon


IMMELMAN
19th Mar 2002, 05:35
I am doing some research on aerodynamic forces and the range of loads that can be experienced when encountering sheer and turbulence. .Most data available is non-destructive ( NDT ) but I want to see when it will break. .I have often discovered parts of pigeons and other birds in my garden - obviously having encountered turbulence and broken up in flight. .I am thinking of doing windtunnel tests on pigeons, but not frozen chickens, 'cos I know they break windshields - they should be thawed out first - however, I still maintain that if you do meet a chicken-strike, it probably will be fozen. .Do any of you have any data on g-factors, stress vector reversals, etc that will cause a pigeon to break up in flight? If it is valid data, I will see you get a mention in the credits of my 'learned' paper. .ps; 'Management' tells me that the bird remains are because we have a cat - she did not know that if she capitalised that statement to 'CAT', she may have been on to something - thank you all for your help <img border="0" title="" alt="[Confused]" src="confused.gif" />. . . . <small>[ 19 March 2002, 00:38: Message edited by: IMMELMAN ]</small>

Throtlemonkey
19th Mar 2002, 07:01
IMMELMAN I would be verry interested to hear what the Vne of a pigeon is, also thier + - ultimate g load,do they delaminate at high speed (loose feathers) or would they sufer structural failure.

Jet Dragon
19th Mar 2002, 07:09
I have noticed that Pigeon fluid systems do tend to leak at both low & high speeds, and when on the ground a drip tray should be used.. .. .Whether this leakage is increased when pushing the limits of the flight envelope is perhaps a matter for further flight testing!!. .. . <img border="0" title="" alt="[Smile]" src="smile.gif" />

henry crun
19th Mar 2002, 08:51
Immelman, shouldn't be too hard to find a whole dead pigeon.. .. .Weigh bird and then carry out some destructive testing. . .. .After that it should be a relatively simple matter to calculate what forces are required for pigeon to breakup in midair. <img border="0" title="" alt="[Smile]" src="smile.gif" />

Blacksheep
19th Mar 2002, 09:16
You state "obviously having encountered turbulence and broken up in flight" This is not obvious. Perhaps the pigeons suffered catastrophic structural failure as a result of exceeding their Vne for some reason. After all, they do not have the benefit of Airspeed Indicators or Overspeed Warning systems to warn them that they are flying too fast. Again, they may have been committing suicide and deliberately nosed themselves over into a terminal manouver. Without a full survey of the wreckage, how can you tell if the break-up was not perhaps preceded by gross tail feather seperation induced by latent damage for example? Such damage is a common result of close feline encounters while on the ground for refuelling or procreation. Before making such claims you must back track the wreckage trail, carefully marking the position of each piece of pigeon as it lies, and then carefully analyze the wreckage map. . .. .Off you go then, back into the garden with paper and pencil. Lets have a bit of scientific rigour in this investigation, instead of the usual wild claims and unjustified speculation.. .. .**********************************. .Through difficulties to the cinema

Dale Harris
19th Mar 2002, 09:51
I usually find their structural integrity non existent after meeting a load of No 4 shot.

gas path
19th Mar 2002, 14:34
Blacksheep is right detailed site analysis is required before jumpng to conclusions. . .I looked out of the window this morning and low and behold a pile of feathers and other debris! At first inspection it looked like a clear case of TCAS failure and controlled flight into terrain, in this case....The patio door. The debris field is very contained being only about 3 ft across, with some evidence of hydraulic fluid and fuel around the crash site, but on looking further afield aprox. 25 feet away is a wing complete and relatively intact. The conclusions are structural failure (very doughtful) Or, the next door neighbours CAT .....Now where do I keep those half bricks? <img border="0" title="" alt="[Wink]" src="wink.gif" /> <img border="0" title="" alt="[Wink]" src="wink.gif" />

Loki
20th Mar 2002, 00:21
I ran over one of the poor creatures recently whilst doing about 60 knots; the bang was quite impressive,clearly audible over "money for nothing" at high volume. I suppose its lungs were fully inflated at the time. Looking in my rear view mirror, all I could see were feathers.

DX Wombat
20th Mar 2002, 00:50
IMMELMANN which species of pigeon are you requiring for your tests? Would you prefer Wood Pigeons, a large, robustly constructed version, or the Feral Pigeon, a medium built bird, or perhaps the Collared Dove, a rather pretty immigrant lightweight from the East? <img border="0" title="" alt="[Roll Eyes]" src="rolleyes.gif" /> <img border="0" title="" alt="[Eek!]" src="eek.gif" /> <img border="0" title="" alt="[Cool]" src="cool.gif" />

Squawk 8888
21st Mar 2002, 07:17
Are you testing African pigeons or European pigeons?

ft
21st Mar 2002, 14:25
I recall reading some test reports from the early stages of swallow development. Apparently, swallows with an external load were prone to suffer from severe mach tuck*. Perhaps it was an experimental pigeon which succumbed to a similar problem?. .. .If I were you, I would start by searching area surrounding the crash site and the area around the flight path up to the impact for evidence of an external load. Often pieces of coconut shell or pieces of string can be found, indicating an emergency jettison of cargo.. .. .*) Yes, even at very low speeds. Swallows were found to assume that they were flying at above mach 1 when they could no longer hear their engines. Coupled with the lack of engines, this had dramatic effects and led to psychosomathic mach tuck.. .. .Cheers,. . Fred

The Nr Fairy
21st Mar 2002, 15:05
ft :. .. . European or African ?. .. .(Someone had to ask !)

Send Clowns
21st Mar 2002, 15:31
Nr - I was once v bored and asked Alta Vista, the 'plain language' search engine "what is the maximum airspeed velocity [sic] ofan unladen swallow?". I came up with the answer "What, African or European?" <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> Then of curse it gave links to script website.

Feeton Terrafirma
21st Mar 2002, 16:31
Considerations:. .The Vne of a pigeon varies with configuration, as does the ability to carry load and the G forces sustainable without CATastrophic failure. There are a number of configurations used by the common pigeon, take off, climb, cruise, aerobatic, decent, short final, and landing to name the commonly use ones. . .. .When considering the load being carried you should not only consider externally borne loads but internal loads, such as the fuel and exhaust situations. . .. .Observations:. .. I have observed on a number of occasions that when pigeons in the cruise configuration experience rapid acceleration to a velocity approaching twice their cruise speed they usually suffer an internal structural failure in the process. I note however that this does not result in separation of any of the major components and usually only a few non-structural feathers are lost in the initial acceleration, and resultant new velocity. There is some speculation that the internal structural failure is a direct result of the hawks talons gripping the fuselage rather than the associated acceleration however.

abeesley
21st Mar 2002, 20:49
I recall reading a similar arcticle on geese. It stated that they were actually considered as lighter-than-air machines. It conclusively reported that in order for a goose to get airbourne it would have to jettison it's internal ballast.. .. .Few geese seem to suffer from CATastrophic faliure, due to their structural integrity. However, due to their direct compatability and replaceability with the turkey, some do have limited hours/cycles which tends to expire around Dec 25th on some parts of the world.

Hugh_Jass
22nd Mar 2002, 01:33
Pidgeons are Suceptible to Long range attack with .22 calibre lead pellets, when fired at high velocity. Perhaps this is what caused the large mass of feathers, and not the exceeding of Vne. You may want to check for impact markings around the area.. .. .HJ

Al Weaver
22nd Mar 2002, 05:15
I hate to get too technical and put realism on this topic.. .. .The bird feathers that you see in circular splat shapes on the ground are birds that have been caught and carefully plucked and eaten by a predator (hawk/fox/.kittycat, etc.). .. .The pieces of birds complete with feathers found on runways, have not been hit by planes or engines but rather subcomed to turbulence from being caught under a wing in the downdraft. Whole birds simply indicate less turbulence. .. .Birds that hit the aircraft at speeds greater than 100 kts simply turn inside out and spray like raw hamburger. I doubt that clear air turbulence is anywhere near as powerful as the turbulence from being overrun by a big jet and being caught within 20 ft of the ground

Al Weaver
22nd Mar 2002, 05:22
I hate to get too technical and put realism on this topic.. .. .The bird feathers that you see in circular splat shapes on the ground are birds that have been caught and carefully plucked and eaten by a predator (hawk/fox/.kittycat, etc.). .. .The pieces of birds complete with feathers found on runways, have not been hit by planes or engines but rather subcomed to turbulence from being caught under a wing in the downdraft. Whole birds simply indicate less turbulence. .. .Birds that hit the aircraft at speeds greater than 100 kts simply turn inside out and spray like raw hamburger. I doubt that clear air turbulence is anywhere near as powerful as the turbulence from being overrun by a big jet and being caught within 20 ft of the ground

abeesley
22nd Mar 2002, 06:43
Yeah, ok ok I heard you the first time. Wot wot.

sprocket
22nd Mar 2002, 17:06
To understand this phenomenon, we must look at causes gentlemen; the pigeon’s airframe has evolved to withstand all operations in the normal categories. I feel that the key to these cataclysmic events that occur to the pigeoniod airframe is the simple egg!. .Would it be that the ‘on board cargo’, that some of the pigeons carry (namely the female of the species) could explode with a drop in atmospheric pressure at altitude?. .If an egg was being carried at altitude, it could explode inside the hapless mother causing her orifices to open briefly. With the resultant venting and breaking of the pigeons’ outer structural seal to a lower atmospheric pressure, it would be virtually impossible to prevent the birds’ remaining internal pressure from releasing with an explosive intensity.. .. .What happens from that moment is entirely predictable: . . . . 1. All hydraulics will be lost.. .2. Vne would be met and exceeded in an instant.. .3. If the wings are not retracted, the drag force induced at high velocity will rip them off.. .4. The head will go next ….. As the bird predictably looks rearward to see where it wings (and @rse) went, its natural streamlining will be thwarted. The buffeting, induced by the suddenly increased drag will cause the wingless projectile to commence a tumbling sequence which changes its aerodynamic profile as each time a part is ripped off.. .5. The mach tuck would develop in to the greatly feared “ Muck Tuck”. The evidence of which you find on the ground afterwards.

Blacksheep
23rd Mar 2002, 14:04
A humming bird was having a meal from the pot-plants and bougainevillae on my living room patio. For some reason it then flew into the living room and was caught in the circulating draught from the ceiling fan. Carried up to the ceiling, it was then drawn down into the fan from above and the resulting debris field was scattered around the room. Interestingly, the wings came off intact and, passing through the fan undamaged, came to rest on opposite sides of the room. Since the primary accident cause was already established by first hand observation, there was no point in an attempt to reconstruct the wreckage and the maid began clearing up the mess. Upon examination of the fan there was no evidence of impact nor of fuel or hydraulic fluid. The conclusion is that the severe turbulence within the arc of the fan blades caused catastrophic structural failure, reducing the humming bird to pieces so small that they had insufficient energy to break through the boundary layer of the individual blades. The tiny creature wasn't chopped up so much as torn up. Things aren't always as certain as they seem.. .. .**********************************. .Through difficulties to the cinema

max_cont
23rd Mar 2002, 17:20
sprocket, that hypothesis is brilliant. The most likely scenario in my opinion. . .. .What we need now is an exhaustive study of the crash sites of all avian species (this phenomena must affect all species) to determine the sex of the deceased aviators.. .. .This could be tricky but I’m sure there must be a few clues left that would help the trained observer make a diagnoses. . .. .If any trained observer could step forward (Slasher springs to mind) and instruct interested parties in the technique, we can start to compile an authoritative database. <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />

ExSimGuy
24th Mar 2002, 21:47
Something wrong here guys. <img border="0" title="" alt="[Frown]" src="frown.gif" /> Although I've never driven a 747-300 other than one of those that flies all the time at FL0.1, I've frequently driven various machines in excess of V1 (Fords, BMWs, etc - and even an Astra which appeared to attain VR <img border="0" title="" alt="[Smile]" src="smile.gif" /> ). .. .One thing that I have noticed is that pidgeons entering the high pressure zone in front of a large object moving at high speed will experience a phenomenum that I call "differential lift". This is due to the fact that they cannot posibly be exactly dead-centre to the approach of the large moving object, and the high pressure zone is stronger towards the centre-line as it approaches the boundary layer. This causes the wing nearest the centre-line to exhibit a higher lift, causing roll and thus a change of direction away from the centre-line (perhaps if the pidgeon had anhedral, instead of dihedral, on its wing, this may not apply - more research needed on this) and passes to the side of the object.. .. .The exception which proves this rule is the one that achieves the statistically impossible feat of being exactly on the centre-line and has to be washed out of the radiator (the Astra equivalent of the first stage fan on a 747, for the non-technically-minded). .. .I will be following this thread with great interest as higher investigation into airflow phenomena is something that has always interested me <img border="0" title="" alt="[Smile]" src="smile.gif" />

HOVIS
26th Mar 2002, 06:26
If it was a European pigeon, is it possible that structural failure could have occurred because..... .. .1. Wake turbulence encountered from a swan several meters ahead.. .2. Large control inputs from our feather brain in attempting to control said wake turbulence.. .3. Perhaps a previous medical condition at birth didn't show up on the CAT scan. . .4. Maybe it has just ceased to be, bleedin' demised, it is an ex pigeon!! <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />

Flight Detent
26th Mar 2002, 15:22
Hi all,. .The immortal words spoken in the classic movie "In search of the holy grail", amongst others, were something to the effect that" before you cross this bridge you must answer questions three!" - and one of those questions refers to the velocity and carrying capacity of a pidgeon! - and that movie was set in the time of King Auther - still the greatest, most entertaining movie I have ever seen - I still can't stop laughing all the way through! (except maybe some of the part with the 'maneating rabbits'). .. .If any of you haven't seen it, you MUST at least try it once, not everybody will love it, but I think it's absolutely great!. .Cheers

aidybennett
26th Mar 2002, 21:10
Seagulls seem to be vunerable in the landing configeration. When approached by a high speed ground veichle, (ie, my car in normal operationing mode) a seagull appears to usually be able to accerelate quickly and climb out of danger. However, when in the landing configeratio with gear and flaps down, they ussually seem to take some time to clean up enough to climb and accelerate, by which time it is they are being effected by the slipsteam of the approaching veichle. The resulting turbelence frequently results in disintergration of the primary surface skin (feathers) of the seagull, and the debris field is therefor widespread.

henry crun
27th Mar 2002, 02:37
I have experienced the same effect on harrier hawks.. .. .They are particularly vulnerable when attempting a vertical takeoff with parts of road killed hedgehog or possum entangled in their talons.

AirScrew
27th Mar 2002, 16:02
This excellent scientific crash investigation seems to have completely overlooked one very important fact.. .. .To whit, the modern pigeon (european), now benefits from an early release of flight control software, still under test, and is combined with a modified fly-by-sinew control system.. .. .This system is still in the testing phase, and all tests have been carried out in close proximity to more sophisticated avaition 'birds', such that the pigeon community can benefit from the research facilities of the AAIB.. .. .Early results show evidence of 'uncommanded control inputs', resulting in catastrophic failure and subsequent 'body parts spread' on faster aviation devices or indeed terra firma. . .. .The motivation of the modern pigeon community seems to be to emulate the seagull family, who in the form of Jonathan Livingstone, have shown that the transition through Vne can not only be achieved, but can transport the pilot into another world, without the painful and terminal impact that appears to be taking these pigeons to their final destination....

Soaring Sprog
27th Mar 2002, 19:42
I swear to god I've seen a Pigeon do a flick roll. I'd be interested to learn more of their aerobatic capabilities, like, can they do tail slides, fly inverted etc...