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A380 & 787 Landing Gear Question  
User currently offlineBritJap From Japan, joined Aug 2006, 280 posts, RR: 2
Posted (6 years 10 months 4 days 5 hours ago) and read 9457 times:

Not so much a question about the landing gear itself, rather the actuation systems used for gear extention/retraction.

I know that Airbus really tried to develop and push the MEA concept forward for the A380. Due to its very large size the benefits are particularly significant. But what I want to know is has this led to EHA or EMA actuators being used for the landing gear? Same question goes for the 787 as well.

If the answer is no, then are there any aircraft using these actuators for the landing gear?

If the answer to that one is no as well then what do you think will be the first aircraft to utilise this technology?

Feel free to mention if you know of other areas where these actuators are used on an aircraft, but I am specifically asking about landing gear actuation.

Regards

16 replies: All unread, jump to last
 
User currently offlineJetMech From Australia, joined Mar 2006, 2692 posts, RR: 53
Reply 1, posted (6 years 10 months 4 days 4 hours ago) and read 9443 times:

Quoting BritJap (Thread starter):

I think the electro / hydraulic actuators are used as a backup on flight controls only.

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 2, posted (6 years 10 months 4 days 2 hours ago) and read 9414 times:

AFAIK, EHA on the A380 have been chosen for the back-up braking system (named Full Brake by Wire) and as a for the steering control system of the nose landing gear.
For what I've understood EHA are providing back-up or an momentary increase of power for the primary flight control system (elevator, ruder, ailerons) when needed.

Regards, David


User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 3, posted (6 years 10 months 4 days 1 hour ago) and read 9383 times:

Quoting FWI747 (Reply 2):
named Full Brake by Wire

Any data on this.
regds
MEL



Think of the brighter side!
User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 4, posted (6 years 10 months 4 days ago) and read 9372 times:

Quoting HAWK21M (Reply 3):
Any data on this.

Here are two links (pdf) :

http://www.fzt.haw-hamburg.de/pers/S...007_09_27_A380_Flight_Controls.pdf

And :

http://www.messier-bugattiusa.com/IMG/pdf/A380.pdf

regds

David


User currently offlineSEPilot From United States of America, joined Dec 2006, 6897 posts, RR: 46
Reply 5, posted (6 years 10 months 3 days 21 hours ago) and read 9307 times:

When I was involved in the design of the world's first totally computerized grinding machine it the late 1970's one of our design goals was the elimination of hydraulics. This was accomplished initially, but as the machine evolved in the 80's it was discovered that when heavy loads have to be moved smoothly, there really is no substitute for hydraulics. Electro-mechanical operators end up being more expensive, more complex, heavier, bulkier, and less reliable than hydraulics, even with all the drawbacks that hydraulics bring. Granted, electro-mechanical actuators have improved greatly since then, but I suspect that they still aren't competitive with hydraulics for things like landing gear actuators. When you see excavators and backhoes start using electro-mechanical instead of hydraulic actuators then I believe that aircraft landing gear actuators will follow.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 6, posted (6 years 10 months 3 days 20 hours ago) and read 9293 times:

Quoting SEPilot (Reply 5):
Electro-mechanical operators end up being more expensive, more complex, heavier, bulkier, and less reliable than hydraulics, even with all the drawbacks that hydraulics bring. Granted, electro-mechanical actuators have improved greatly since then, but I suspect that they still aren't competitive with hydraulics for things like landing gear actuators. When you see excavators and backhoes start using electro-mechanical instead of hydraulic actuators then I believe that aircraft landing gear actuators will follow.

 checkmark 

However, I recall that NASA tested an F16XL equipped with that type of actuator some years ago. Can anyone out there confirm it ?
And on a side note what type of operator does the F35 use ? EHA ?

David


User currently offlineSEPilot From United States of America, joined Dec 2006, 6897 posts, RR: 46
Reply 7, posted (6 years 10 months 3 days 19 hours ago) and read 9266 times:

Quoting FWI747 (Reply 6):
However, I recall that NASA tested an F16XL equipped with that type of actuator some years ago.

NASA often does things long before they become viable for commercial applications; sometimes they actually work and lead to widespread use. Other times they make expensive toys. It would not surprise me if eventually electro-mechanical actuators do replace hydraulics in aircraft landing gear; it also would not surprise me if they never do.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 8, posted (6 years 10 months 3 days 19 hours ago) and read 9259 times:

Quoting SEPilot (Reply 7):
NASA often does things long before they become viable for commercial applications; sometimes they actually work and lead to widespread use. Other times they make expensive toys

 yes 


User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 9, posted (6 years 10 months 3 days 19 hours ago) and read 9252 times:

Some aircraft use electric gear actuation already:

View Large View Medium
Click here for bigger photo!

Photo © Bruce Leibowitz



Heck, some even use manual gear actuation (the infamous "Johnson Bar" gear):

View Large View Medium
Click here for bigger photo!

Photo © Terry Shepherd


EDIT: It should also be added that many GA types use an interesting hybrid system for the landing gear, with an electric motor driving the hydraulic pump. I guess that's for the GA types where the hydraulic system is doing nothing more than raising and/or lowering the landing gear...

[Edited 2007-11-01 11:41:01]


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineSEPilot From United States of America, joined Dec 2006, 6897 posts, RR: 46
Reply 10, posted (6 years 10 months 3 days 17 hours ago) and read 9209 times:

Quoting KELPkid (Reply 9):


EDIT: It should also be added that many GA types use an interesting hybrid system for the landing gear, with an electric motor driving the hydraulic pump. I guess that's for the GA types where the hydraulic system is doing nothing more than raising and/or lowering the landing gear...

This is the electro-hydraulic system talked about. Yes, many GA aircraft use different methods, but the fact that it is possible to do manually (i.e. the Johnson bar) indicates that the force required is really quite low. How big do you think the Johnson bar would have to be on an A380?



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 11, posted (6 years 10 months 3 days 17 hours ago) and read 9190 times:

Quoting SEPilot (Reply 10):
How big do you think the Johnson bar would have to be on an A380?

I would imagine that it would extend from the lower passenger deck to the upper, and require at least 10 people to activate...

"And we here at Singapore Airlines would like to remind those seated in the first section on the upper deck to reivew the safety card, as you may be called upon to help in the event of a landing gear malfunction..." Big grin



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineSEPilot From United States of America, joined Dec 2006, 6897 posts, RR: 46
Reply 12, posted (6 years 10 months 3 days 16 hours ago) and read 9183 times:

Quoting KELPkid (Reply 11):

"And we here at Singapore Airlines would like to remind those seated in the first section on the upper deck to reivew the safety card, as you may be called upon to help in the event of a landing gear malfunction..."

 bigthumbsup 
Sounds like fun; think they'll implement it?



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineBrenintw From Taiwan, joined Jul 2006, 1633 posts, RR: 1
Reply 13, posted (6 years 10 months 3 days 12 hours ago) and read 9123 times:

Quoting KELPkid (Reply 11):
would like to remind those seated in the first section on the upper deck to reivew the safety card, as you may be called upon to help in the event of a landing gear malfunction

It would be more a case of "would like to remind those passengers seated at the back that they might be called to walk to First Class to assist ..."

Heaven help the F/A who asks a F/C pax to do anything other than sleep!



I'm tired of the A vs. B sniping. Neither make planes that shed wings randomly!
User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 14, posted (6 years 10 months 3 days 4 hours ago) and read 9069 times:

Quoting Brenintw (Reply 13):
Heaven help the F/A who asks a F/C pax to do anything other than sleep!

So true !  rotfl 


User currently offlineRebelDJ From United Kingdom, joined May 2007, 112 posts, RR: 0
Reply 15, posted (6 years 9 months 3 weeks 5 days 1 hour ago) and read 8735 times:

Quoting FWI747 (Reply 2):
AFAIK, EHA on the A380 have been chosen for the back-up braking system (named Full Brake by Wire) and as a for the steering control system of the nose landing gear.

Not quite right. The braking system on the A380 has two parts - the "power" and the "control". The brakes are powered by the two hydraulic circuits on the a/c and they are controlled (activated) by wires linking them to the centralised computers on the a/c.

The steering system is a conventional Airbus hydraulic push me - pull you opposed hydraulic actuators, again controlled by the centralised computer system.

Neither braking nor steering use EHA. They do use a Local ElectroHydraulic Generating System (LEHGS) which is described on the Messier Bugatti link you posted - but this is a standby reservoir/pump system - not an EHA.

The only systems on the A380 using EHA/EBHA are the flight controls (which is why the a/c can meet it's safety objectives with just the two hydraulic systems).

The 787 on the other hand is the first a/c to use electric brakes - i.e. no hydraulics.


User currently offlineFWI747 From France, joined Jul 2007, 71 posts, RR: 0
Reply 16, posted (6 years 9 months 3 weeks 4 days 20 hours ago) and read 8681 times:

Quoting RebelDJ (Reply 15):
The only systems on the A380 using EHA/EBHA are the flight controls (which is why the a/c can meet it's safety objectives with just the two hydraulic systems).

 checkmark 


Thanks for this clarification  Smile


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