Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Tail Strike Protection - Is Any Automated?  
User currently offlineJulianUK From United Kingdom, joined Apr 2006, 105 posts, RR: 0
Posted (8 years 6 months 4 days 19 hours ago) and read 10074 times:

Reading about tail strikes, surely it should be automated, if you are going to tail strike there should be an automated warning that you are seconds away from scraping the back, and if you persists a forced pitch down through perhaps a radio altimeter at the back or some sort of distance protector. From what I understand you can still, even in the most modern of aircraft, pull the stick back strike the tail and cause a lot of "issues" as my pilot friends likes to call them..... Smile

J

44 replies: All unread, showing first 25:
 
User currently offlineDw747400 From United States of America, joined Aug 2001, 1264 posts, RR: 1
Reply 1, posted (8 years 6 months 4 days 19 hours ago) and read 10080 times:

I believe the A340-600 and 777-300ER have some form of electronic tail protection. Both are very long aircraft that require a significant amount of rotation at MGTOW. I'm sure someone has more detailed information.


CFI--Certfied Freakin Idiot
User currently offlineDavid L From United Kingdom, joined May 1999, 9533 posts, RR: 42
Reply 2, posted (8 years 6 months 4 days 19 hours ago) and read 10064 times:

Quoting Dw747400 (Reply 1):
Both are very long aircraft that require a significant amount of rotation at MGTOW.

Isn't it more to do with the fact that they require less rotation to strike the tail on the runway?


User currently offlineDw747400 From United States of America, joined Aug 2001, 1264 posts, RR: 1
Reply 3, posted (8 years 6 months 4 days 18 hours ago) and read 10056 times:

Quoting David L (Reply 2):
Isn't it more to do with the fact that they require less rotation to strike the tail on the runway?

That is true too. The point I was trying to make is that both the 777-300ER and A340-600 represent dramtic increases in MGTOW compared to the baseline aircraft. Both have some wing modifications, but in general they either need to go faster or rotate to a higher angle of attack in order to produce enough lifts so that lift=weight. Not being a heavy pilot nor having performance charts, I don't have exact numbers, but there is a limit on takeoff speed set by both RTO needs/runway length, and tire speed limits. Thus, simply reducing the rotation angle for a stretch is not an option, and a long, heavy plane will be more prone to tail-strikes than a plane that is either lighter or shorter.

In short, the comment above was a poorly worded way of saying that you can't just reduce the rotation angle.

[Edited 2006-05-22 00:51:49]


CFI--Certfied Freakin Idiot
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 4, posted (8 years 6 months 4 days 17 hours ago) and read 10032 times:

Quoting JulianUK (Thread starter):
Reading about tail strikes, surely it should be automated, if you are going to tail strike there should be an automated warning that you are seconds away from scraping the back

By the time of a warning, the tail strike has occurred so such a system would probably be of minimal value.

Tail strikes on the 737-800/900 are very possible in both takeoff and landing regimes. For takeoff, a slow rotation rate of about 2 degrees/sec is optimal. There is plenty of energy at Vr to accomodate the takeoff w/ the desired rotation rate.

In the case of the 777-300, I believe the gear truck is levered, in that it is locked for takeoff and rotates to remain in parallel with the fuselage. This enables the a/c to rotate off the aft axle as opposed to the center of the truck, which allows a higher initial rotation angle, which in turn provides some tail strike relief and enables shorter t/o distances. Landing is normal, in that the truck will rotate.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17108 posts, RR: 66
Reply 5, posted (8 years 6 months 4 days 16 hours ago) and read 10016 times:

Quoting EssentialPowr (Reply 4):
Quoting JulianUK (Thread starter):
Reading about tail strikes, surely it should be automated, if you are going to tail strike there should be an automated warning that you are seconds away from scraping the back

By the time of a warning, the tail strike has occurred so such a system would probably be of minimal value.

As Mr Powr says, warning times are too short for anything but an automated tailstrike inhibitor.

Regarding the "surely it should be automated" part, you would be amazed how precise pilots can be in their handling of the big birds, and how precisely they can be handled. Just because a 380 or 747 looks ungainly and hard to maneuver doesn't mean that it is. Control surfaces are scaled up to match the rest of the plane.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineHAWK21M From India, joined Jan 2001, 31692 posts, RR: 56
Reply 6, posted (8 years 6 months 4 days 12 hours ago) and read 9966 times:

I've heard that the B777-300ER is equipped with Tail skid that senses the Proximity of it from the Surface below & accordingly sends a signal to Trim the Aircraft nose down to avoid the Strike.
Maybe someone having worked on the B773ER would know in detail.
regds
MEL



Think of the brighter side!
User currently offlineDavid L From United Kingdom, joined May 1999, 9533 posts, RR: 42
Reply 7, posted (8 years 6 months 4 days 5 hours ago) and read 9909 times:

Quoting HAWK21M (Reply 6):
I've heard that the B777-300ER is equipped with Tail skid that senses the Proximity of it from the Surface below & accordingly sends a signal to Trim the Aircraft nose down to avoid the Strike.
Maybe someone having worked on the B773ER would know in detail.

http://www.boeing.com/news/releases/2003/q4/nr_031016g.html

"If the tail gets too close to the ground, the system moves the elevator for slower nose rotation. During abuse takeoff testing, where Santoni has deliberately rotated the airplane early and fast, the system has responded as designed."


User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 8, posted (8 years 6 months 4 days 4 hours ago) and read 9895 times:

The Marconi/BAE HUD provides indications of an impending tailstrike. AA uses it in their 737's


One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 9, posted (8 years 6 months 4 days 4 hours ago) and read 9883 times:

David L, thanks for the reference...

Quoting HAWK21M (Reply 6):
I've heard that the B777-300ER is equipped with Tail skid that senses the Proximity of it from the Surface below & accordingly sends a signal to Trim the Aircraft nose down to avoid the Strike.

There's no sensor in the tail skid of any kind; its just that the flight computer computes the geometry...from the same article:

""It's in the primary flight computer," said Frank Santoni, Boeing 777 chief pilot, of the special feature. "It's a function that looks at rate of closure of the tail to the ground during rotation, measuring how fast and at what distance the tail is moving toward the pavement."


User currently offlineQantas744ER From United States of America, joined Jun 2005, 1289 posts, RR: 4
Reply 10, posted (8 years 6 months 4 days 4 hours ago) and read 9885 times:

Correct, in the case of the 340-600 the Fly-by wire system always knows the max AOA (angle of attack) so that if the pilot would accidentaly not be aware of the the AOA the system would bring the nose back down again.

On any airbus model exept the a300 and a310 the pilot can set a digital pitch bar in the PFD so that he knows he shouldnt pull over that bar. But there was an incident in JNB 2 years ago, were a EK a340 on TO the pilot didnt calculate the V1 Vr V2 properly and accidently used a lower TO speed than needed, and because it was only his second flight on the a340 as a captain, and previously he learned on the a330 that using the pitch bar technique was ok, but a pilot should never only rely on this method.

So on TO the pilot tried to rotate the plane struck its tail for several hundred feet, and finally after the pilot engaged TOGA thrust mode the plane just made it off the RWY dumped fuel and made a successfull emergency landing.

Cheers Leo



Happiness is V1 in Lagos
User currently offlineDavid L From United Kingdom, joined May 1999, 9533 posts, RR: 42
Reply 11, posted (8 years 6 months 4 days 4 hours ago) and read 9878 times:

Quoting EssentialPowr (Reply 9):
David L, thanks for the reference...

No problem - I remembered it from one of those "FBW is Dangerous" discussions!  Smile


User currently offlineHiFi From Brazil, joined Apr 2005, 192 posts, RR: 0
Reply 12, posted (8 years 6 months 3 days 21 hours ago) and read 9786 times:

Tail strike protection is usually achieved with a tail bump... Basically a structure that hits the ground first and doesn't let the real tail hit.

I don't think indication is a solution, as time is very short during rotation. A FBW function to avoid tail strike through limiting elevator deflection in case of tail-ground proximity is possible... and already exists.



no commercial potential
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3702 posts, RR: 34
Reply 13, posted (8 years 6 months 3 days 19 hours ago) and read 9748 times:
Support Airliners.net - become a First Class Member!

Quoting Qantas744ER (Reply 10):
Correct, in the case of the 340-600 the Fly-by wire system always knows the max AOA (angle of attack) so that if the pilot would accidentaly not be aware of the the AOA the system would bring the nose back down again.

That is not correct. A system such as this was tried during development but they found if the a/c pitched down the pilot just pulled back on the stick further. Instead now they have an idication on the PFD




User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 14, posted (8 years 6 months 3 days 17 hours ago) and read 9713 times:

Quoting HiFi (Reply 12):
Tail strike protection is usually achieved with a tail bump... Basically a structure that hits the ground first and doesn't let the real tail hit.

UUhhh...no. That skid is designed to protect the a/c as much as possible, but is certainly not to be used intentionally. If it is hit, the a/c is grounded for a fairly extensive inspection.

Tail strike protection, in the case of both manufacturers, consists of procedures and or software protection to prevent the skid from being hit in the first place.


User currently offlineBobster2 From , joined Dec 1969, posts, RR:
Reply 15, posted (8 years 6 months 3 days 17 hours ago) and read 9696 times:

Would a pilot ever want to do a tail strike on purpose? For example, the KLM pilot in the Tenerife crash caused a tail strike in his attempt to get over the Pan Am plane. I don't know if that was intentional, nor do I know if it helped get the plane off the ground quicker, or if it delayed getting the plane in the air.

If there was some advantage to a tail strike in an emergency, that would affect the protection system.


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 16, posted (8 years 6 months 3 days 16 hours ago) and read 9681 times:

Yes, that has happened. About 2 yrs ago an incident in DFW was avoided when a CAL crew rotated to the skid in a 737 to avoid a Delta a/c.

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17108 posts, RR: 66
Reply 17, posted (8 years 6 months 3 days 5 hours ago) and read 9618 times:

Quoting Bobster2 (Reply 15):
Would a pilot ever want to do a tail strike on purpose?

During unstick speed testing the tail is dragged on the ground. But there's a skid installed to protect the tail.

Also as EssentialPowr says, you could do this for collision avoidance. But could it be that drag from the tail would exceed the advantage?



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineDon81603 From Canada, joined Jul 2005, 1185 posts, RR: 0
Reply 18, posted (8 years 5 months 3 weeks 5 days 7 hours ago) and read 9387 times:

I believe Concorde equipped with a small tire in at the end of the fuse to deal with a tail strike. Could such a system be implimented in other long fuse aircraft, or would it entail a major redisign? I don't know what hydraulic or electrical systems are routed in the area, so...


View Large View Medium
Click here for bigger photo!

Photo © Fergal Goodman



[Edited 2006-05-30 12:23:39]


Eagles may soar, but weasels don't get sucked into jet engines.
User currently offlineVimanav From India, joined Jul 2003, 1520 posts, RR: 14
Reply 19, posted (8 years 5 months 3 weeks 5 days 6 hours ago) and read 9373 times:

Quoting Don81603 (Reply 18):
I believe Concorde equipped with a small tire in at the end of the fuse to deal with a tail strike

As is the IL62.

just an observation.

rgds//Vimanav



Sarfaroshi kii tamannaa ab hamaare dil mein hai, Dekhnaa hai zor kitnaa baazu-e-qaatil mein hai
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17108 posts, RR: 66
Reply 20, posted (8 years 5 months 3 weeks 5 days 5 hours ago) and read 9360 times:

Quoting Don81603 (Reply 18):
I believe Concorde equipped with a small tire in at the end of the fuse to deal with a tail strike. Could such a system be implimented in other long fuse aircraft, or would it entail a major redisign? I don't know what hydraulic or electrical systems are routed in the area, so...

I'm sure it could be, but today you have tail skids doing the same thing.

It should also be noted that the situation might have been a bit more serius with Concorde since the engine exhausts would have hit the ground before the tail if not for the tail wheels.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineTom12 From United Kingdom, joined Dec 2005, 1078 posts, RR: 13
Reply 21, posted (8 years 5 months 3 weeks 5 days 3 hours ago) and read 9347 times:

While we are on the subject of tail strike on a jet, i noticed in one of the photos the other day there that the pad to prevent serious damage had hydraulics of somekind behind it and so i was wondering does this pad come down with the landing gear?

Tom



"Per noctem volamus" - Royal Air Force Bomber Squadron IX
User currently offlineTom12 From United Kingdom, joined Dec 2005, 1078 posts, RR: 13
Reply 22, posted (8 years 5 months 3 weeks 5 days 3 hours ago) and read 9345 times:

http://www.airliners.net/open.file/0675034/L/

This is the image with the 763 and 764's tail strike pads down


Don't have the time to put the image in, sorry!

Tom



"Per noctem volamus" - Royal Air Force Bomber Squadron IX
User currently offlineHAWK21M From India, joined Jan 2001, 31692 posts, RR: 56
Reply 23, posted (8 years 5 months 3 weeks 5 days 3 hours ago) and read 9339 times:

Quoting Tom12 (Reply 22):
Don't have the time to put the image in, sorry


View Large View Medium
Click here for bigger photo!

Photo © Tony Marlow - WorldAirImages


regds
MEL



Think of the brighter side!
User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 24, posted (8 years 5 months 3 weeks 5 days 2 hours ago) and read 9330 times:

Quoting Dw747400 (Reply 1):
I believe the A340-600 and 777-300ER have some form of electronic tail protection. Both are very long aircraft that require a significant amount of rotation at MGTOW. I'm sure someone has more detailed information.

i'm sure Airbus garunteed at some point it was impossible to tail strike a 600!
 rotfl 


25 AJ : Hi Tom, on the 767-300 the tail skid extends and retracts with the landing gear.
26 HAWK21M : How is that Sequenced.Any details.What Logic. regds MEL
27 Sulman : The trouble with automating the protection is that it limits the pilot's options should they want to over-rotate for any reason.
28 HAWK21M : Isn't that a Good thing. What reasons are you qouting. regds MEL
29 Post contains links Pihero : Quoting HAWK21M (Reply 28): Quoting Sulman (Reply 27): The trouble with automating the protection is that it limits the pilot's options should they wa
30 Tom12 : Thanks AJ, Mel
31 Bri2k1 : I'm gonna have to take a guess here that when the landing gear lever is in the "DOWN" position, the tail skid goes down too?
32 OldAeroGuy : The 773ER pilot can still put the tail skid on the runway to satisfy the Vmu speed requirement but the vertical velocity at skid contact will be very
33 David L : But would it get the aircraft airborne more quickly?
34 VC-10 : Famous last words, we'll revisit this in 5 years time.
35 OldAeroGuy : Not sure what you mean. Vmu is about the lowest possible speed for lift off, not how quickly you can lift off.
36 Post contains images David L : Sorry, I have a habit of forgetting that others may not be pursuing the same line of thought as I am . I meant in the context of deliberately "perfor
37 Pihero : I had a conversation with a T7 instructor on the subject and he told me the software had been "changed" to allow the test ; he confirmed the impossib
38 Post contains images David L : Ah, I'd forgotten about that! So, Airbus may be more "evil" but Boeing are sneaking in there. That was my suspicion but far be it for me to suggest i
39 FlyDeltaJets : My guess to as to why the -600 doesn't have a tail skid is it's height off the ground. Am I correct in this thinking
40 OldAeroGuy : The instructor is incorrect. The flight test was performed with the same software that is on the airplane today. If the instructor was correct, the V
41 Post contains links Pihero : I'm going to have a serious argument with this guy ! What he told me was that the Vmu test is just about performance. They established the Vmu/Vlo co
42 Post contains links Chksix : Are the Vmu speeds from testing available somewhere or are they kept secret? I can't find any data in the 737 flight manual. It claims that detailed d
43 Post contains images Chksix : What I'm looking for specifically are: FAR A16WE-§25.101 to §25.149 I guess they are locked up by Boeing
44 Essentialpowr : Yes and no...Tail clearance is a function of the geometry of the a/c (theoretically) rotated about the mains until the tail touches. It is a function
Top Of Page
Forum Index

Reply To This Topic Tail Strike Protection - Is Any Automated?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
What Causes A Tail Strike posted Wed Nov 6 2002 16:19:01 by Clickhappy
747 Tail Strike posted Tue Oct 29 2002 04:36:55 by Mlsrar
What Is The 'Self Protection System'? posted Tue Sep 5 2006 17:50:10 by EI787
757 And 767 RB211 Is There Any Difference In Size? posted Mon Jun 19 2006 14:38:00 by Edumotoki
What Is The Correct Way To Land A Tail Dragger? posted Mon Mar 6 2006 22:45:19 by Jamesbuk
Any Reason The BAC1-11 Is Popular As A Testbed? posted Sat Aug 27 2005 22:57:35 by Sulman
Is That A "tail Collapse"? posted Sun Aug 21 2005 12:43:28 by Pihero
Is Etops 330 Any Closer? posted Mon Jun 6 2005 22:15:34 by Glom
How Much Tail Wind Is Acceptable? posted Sat Feb 19 2005 02:32:57 by Ktachiya
What Is Hole In The Tail For? posted Fri Apr 23 2004 08:33:15 by BEG2IAH

Sponsor Message:
Printer friendly format