Myth Busters Chicken vs airplane windshield 2

[jsummerfield]

In iPilot.com,

http://ipilot.com/forum/message.aspx?pid=77910,

a pilot questions the situation with the testing. A bird strike is a major concern for many pilots. Myth Busters tested a trashed airplane windshield. It failed, exponentially and to several powers. I mean it was real bad.

What agency or testing service or professional society has performed testing of bird strikes on aircraft - Cessna 172 not F-16 for example.

Stay tuned as this could be fun.

John Summerfield, PE and private pilot

John

 

[davidjh]

Are you saying that you are interested in general aviation aircraft only with your "Cessna 172 not F-16" phrase?

If the Type Certification basis requires such testing then the "applicant" (usually the airframe manufacturer) is responsible to conduct such testing after obtaining approval of the "test set-up' and "test article" from the FAA (in the USA) authority. Some manufacturers have their own such facilities, others contract it out to "lab test shops". But all responsibility for the test lies with the applicant.

 

[davidjh]

My second paragraph above obviously refers to "civil" airplanes.

Also see thread "birdstrike analysis" in this forum.

 

[jsummerfield]

MythBusters tested an aircraft windshield by shooting a frozen and perhaps thawed checken throught an aircraft windshield with an air cannon. I do not know the manufacturer or model of the aircraft windshield that was tested. The windshield was from a general aviation plane not a jet fighter.

I will check for birdstrike analysis. However, I doubt that I will find an ASTM method for windshield testing. As many of the likely GA are vintage 1970's, the current FAA certification requirements would not apply. If you know testing standards it would be interesting.

John

 

[jsummerfield]

Thanks. Birstrike Analysis is here:

http://www.eng-tips.com/viewthread.cfm?qid=70083

John

 

[Viking214]

Related issue. Don't forget that wing (fuel tank rupture) and h-stab leading edge structures are also bird strike tested.

 

[Stache]

I search the FAR regulations on windshields and below is what the certification rule is:

Sec. 23.775 Windshields and windows.
(a) The internal panels of windshields and windows must be constructed of a nonsplintering material, such as nonsplintering safety glass.

(h) In addition, for commuter category airplanes, the following applies:
(1) Windshield panes directly in front of the pilots in the normal conduct of their duties, and the supporting structures for these panes, must withstand, without penetration, the impact of a two-pound bird when the velocity of the airplane (relative to the bird along the airplane's flight path) is equal to the airplane's maximum approach flap speed.
(2) The windshield panels in front of the pilots must be arranged so that, assuming the loss of vision through any one panel, one or more panels remain available for use by a pilot seated at a pilot station to permit continued safe flight and landing.

Stache

 

[FieldTeam]

Don't forget that most commercial and military windows are heated. This not only helps with anti-fogging and anti-icing, but also increases the windows elasticity.

 

[jetmaker]

My understanding is that for general aviation aircraft such as a C172, birdstrike requirements are not mandatory. 2 reasons for this being the slow speed of these airplanes which allows the bird to get out of the way; and secondly, the prop being located in front of the pilot to reduce the bird before impact.

This is simply my understanding as was explained to me when learning to fly. I have no formal documents to support these statements at this time.

Regards,

jetmaker

 

[Stache]

There is a lot of miss information being passed on by CFI's who really don't know what they are talking about when it comes to airworthiness standards. All small aircraft have to meet the requirement of Part 23 to receive a Type Certificate Data Sheet (TCDS) or (T/C). In accordance with the aircraft Airworthiness Certificate in every aircraft it says they still have to meet the part 21, 43, 91 rules to remain valid. So if the CE-172 came with a 1/8-inch thick windshield it has to have one that will with stand a bird strike to meet the minimum standard.

Stache

 

[jsummerfield]

Before Part 23, many GA planes were certified to CAR 3.

John

 

[aerodog]

If Myth Busters used a frozen or even a thawed chicken,
they may have well used a rock.

The Lear Jet Model 23 weighed less than 12,500 lbs and was a CAR/CAM Part 23 aircraft. No bird testing was required.

The Model 24 weighed more than 12,500 and fell into the Air Transport Category FAR Part 25, where bird proof testing was required.

For the testing, four pound chickens were shot out of a compressed air cannon at the maximum cruise speed of the airplane at 10,000 ft (or below).

After dozens of shots and dozens of destroyed windshields, the company finally qualified a windshield.

To pass the test, max airspeed was reduced from 350 KIAS to 306 KIAS. Energy goes up with the square of the velocity and 350 knots was just out of reach.

The chickens were freshly killed. A cardboard box with a hose to an auto exhaust did the dirty deed. The slightest set of rigor mortis made a huge difference.

No further bird testing was required until the company sold a Model 25 to Lord Waterpark in England. The ARB (British Certification Authority) required bird proofing of the nose section.

So Learjet dusted off the cannon, lowered the sight about 18 inches and fired the recently deceased four pound chicken at 306 knots into the aluminum skin of the nose section.

The bird penetrated the skin, the nose avionics bay, the forward pressure bulkhead, the co-pilots seat, and the cabin/cockpit divider.

 

[WKTaylor]

Folks...

At first, I watched a few "myth-busters" shows and thought their techniques were for investigating "interesting" phenomena were convincing... then slowly my opinion evolved to "very different/odd".

When they had a show on explosion hazards of flammable materials [gasoline ignition by static electricity, paint cans in-the-back-seat, etc], then I realised they are just TV buffoons. >>>There was NO scientific basis-to, or understanding of fire/explosion science, that led to the very "stupid" tests they ran. Period.<<<

Regards, Wil Taylor

 

[RVSWA]

When "Adam" gots his lip sucked into the impeller of a vacum assembly, I reclassified it as "Jackass" for geeks. I still love the show for the "make it from scratch" crap they put together. I appreciate the creativity/ingenuity, ASTM be damned...

 

[evelrod]

Lip? ;-) That's not what I read.

Rod

 

[sreid]

Myth Busters repeated the experiment using multiple layers of glass. The thawed bird cracked the glass. The frozen bird blew a hole straight through.

 

[FredGarvin]

Will,
Neither of the guys on that show has a science background. I think they both worked in special effects area for shows and movies if I remember correctly. In their defense the only thing they do is to recreate the urban myths as they appear in circulation. I don't flaw them for their test set ups. I do find flaws in many of their conclusions though.

I did see a show over the holidays that had them going back to revisit some of their previous tests. They got so many letters and such about things they should have done that they had to try them out.

 

[awparran]

I lived in Lavonia, Michigan in the mid 80's and remember a helicopter pilot being knocked cold turkey when hit by a Canadian Goose traveling on the same flight path.

Fortunately the pilot had the autopilot on and came too over Lake Erie, or was it the Detroit River? Anyway, there was a lot of speculation regarding this series of events and the last I heard the pilot was fired and later rehired by another news agency.

As a novice in physics several questions came to mind. Was the goose frozen or thawed? Do Canadian Geese freeze? Was it a head on or oblique collision? Why wasn't the goose sliced and diced by the blades first? These questions came to mind since everything that I had read up to that point stated you had to be traveling at "X" velocity to create such an event. The downwash of the helicopter blades would have destroyed any lift the wings of the goose had generated, thus forcing the goose down and under the helicopter.

As a pilot myself, I have never had the opportunity to fly near a bird, or they have never had the oppotrunity to fly near me. Either way from that story I have always included looking for flying Canadian Geese as part of my out of the cockpit scan.

I know for sure that they have a very poor survival rate when ingested into engines.

 

[karlbamforth]

When I was working for the RAF I had to fix a helicopter where a bird had passed through the lower windscreen and practically destroyed the co-pilots seat (luckily) just below the cushion he was sitting on. It was only a crow sized bird and obviously was not affected by downdraft, may have been fired from an air cannon I guess. If I remember correctly light aircraft were exempt windscreen tests in the past. When the requirements changed they had grandfather rights so carried on in production. Any newly certified aircraft would have to meet the current requirements.

 

[Sparweb]

Pilots of the PBY Catalina used to joke that the only bird strikes they suffered were from behind.
(The planes were painfully slow).

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout