LeDragon
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Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 9:36 pm

I just got in an argument where someone made fun of me. So I come here, where members are more respectful, to ask the question : could a 777, be it a 200 or 300, take off with one engine only ?
As a matter of fact, there are two questions here :
-if an engine fail after the plane reach V1, would the pilots keep on and take off ?
-since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine ?
Obviously, there should be easy condition. Let's say an airport in low altitude ( under 1000 feet ), a cool day ( 50 degrees Fahrenheit ), a front wind ( let's say 5 knots ), a long runway ( 12 800 feet ) and a medium load ( I don't know what it means for a 777...).
Waiting for your answers !
A simple passenger !
Yvon LeD
 
Matt72033
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 9:51 pm

Quoting LeDragon (Thread starter):
if an engine fail after the plane reach V1, would the pilots keep on and take off ?

yes, once the aircraft reaches V1 it is commited to flight!

Quoting LeDragon (Thread starter):
since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine

probably!
 
777DadandJr
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 10:16 pm

Quoting Matt72033 (Reply 1):
Quoting LeDragon (Thread starter):
if an engine fail after the plane reach V1, would the pilots keep on and take off ?

Yes,

Quoting Matt72033 (Reply 1):
Quoting LeDragon (Thread starter):
since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine

and yes.

During the development and testing program for the 777, one of the tests done is to simulate an engine failure on take off. Yes, the 777 did get off the ground. I believe that this is a standard flight test performed on any new aircraft for certification purposes.

Russ wave 
My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.
 
Matt72033
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 10:19 pm

Quoting 777DadandJr (Reply 2):
During the development and testing program for the 777, one of the tests done is to simulate an engine failure on take off. Yes, the 777 did get off the ground. I believe that this is a standard flight test performed on any new aircraft for certification purposes

the requirement is that take off must be achieved when one engine is lost!
this is why big twins have huge engines with extremely high thrust levels as when they lose an engine the lose 50% of their thrust as opposed to 25% if it were a quad!
 
PhilSquares
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 10:57 pm

Quoting LeDragon (Thread starter):
if an engine fail after the plane reach V1, would the pilots keep on and take off ?

Yes, in fact, there is no decision at all, you have to continue because you probably won't be able to stop.

Quoting LeDragon (Thread starter):
since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine ?

Given the conditions you mentioned, my answer would be no. Here's why. First of all, you couldn't set takeoff power on the one good engine since you're below VMCG. You don't have enough control authority to keep the aircraft on the runway with that amount of power.

So, you'd have to set something less, way less than takeoff power and accelerate to a speed at or above VMCG and then you'd have the control authority to set takeoff power on the one engine. That will take some runway.

As far as that type of test being done during certification, I'm not aware of that since that's not a requirement of the certification. In fact, no aircraft is required to demonstrate that. You can't because of the fact you have a VMCG.
Fly fast, live slow
 
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Starlionblue
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 11:29 pm

Quoting LeDragon (Thread starter):
-if an engine fail after the plane reach V1, would the pilots keep on and take off ?

As previous posters have pointed out, yes. The whole point of V1 is as a decision speed. That is, at or after V1 you take off whatever happens, unless you have very serious doubts about the ability of the aircraft to fly. Burning engine, go. Left wing fell off, stop.

Consequently, it would be unreasonable to design a multi-engine airplane without the ability to take off with an engine out engine from V1 (for twins, this means on one engine). Certification requirements reflect this.

However, getting to V1 is another thing. As PhilSquares points out, it's not a matter of power but of control. The nosewheel and the rudder would not be able to keep the plane on the runway with on engine at take off power and the other off.

Quoting LeDragon (Thread starter):
-since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine ?

Maybe you could, with a very looooong runway, start up on one engine at much reduced power and continue from there, holding back on take off power until VMCG, that is the speed at which you can manoeuvre.

But there is really no point in this as a certification requirement. At the speeds we are talking about, you are way below V1 and would thus be able to stop beofre the end of the runway. That is, if one engine failed you would just stop.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Tristarsteve
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 11:30 pm

I have been a passenger in a Tristar which took off with only two engines. The Nbr 3 had failed in KHI, and we ferried it back to BAH for an engine change. After all the preparation, you set max thrust on Nbr2 engine, and let off the brakes. As the aircraft accelerates you feed in power to the good engine at the ratio of N1 to speed, i.e. at 60knots you have 60% N1, acheiving 100% power at 100kts. This keeps the aircraft on the runway. It also wears out the nosewheel tyres which must have a certain tread depth before you start.
I can't see how you could do it on a B777, as , as soon as you set enough power, you would be off the side of the runway.
 
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Starlionblue
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RE: Could A 777 Take Off With One Engine Only?

Tue Dec 27, 2005 11:38 pm

Quoting Tristarsteve (Reply 6):
I can't see how you could do it on a B777, as , as soon as you set enough power, you would be off the side of the runway.

Well, I assume you can taxi a 777 on one engine just like lots of other twins. Once you are up to taxi speed, feed in the power just like on the Tristar. But this would require a loooooong runway and is a pretty pointless test for anything but A.nut bragging rights.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
AJ
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 9:08 am

I've done a single engine takeoff as a handling exercise in the 767 simulator. Full live side rudder is applied and the power increased slowly to maintain directional control. Once accelerating through Vmcg full power was achieved and some rudder relaxation was required to maintain centerline. Quite amazing!
 
don81603
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 9:47 am

Quoting PhilSquares (Reply 4):
VMCG

Dare I ask what VMCG stands for?
 confused 
Eagles may soar, but weasels don't get sucked into jet engines.
 
bri2k1
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 10:27 am

ALL airliners can take off with one engine failed, and continue to climb, too. Vmcg is the speed below which control with one engine is not possible; it's mostly due to the size of the rudder and vertical stabilizer, because with an engine out and asymetric thrust, a large rudder correction is required to maintain straight flight.

This is not true of light twins, which upon engine failure, may not be able to maintain a positive rate of climb. It's required for certification of an airliner though.
Position and hold
 
PhilSquares
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 11:18 am

Quoting Don81603 (Reply 9):
Dare I ask what VMCG stands for?



Quoting Bri2k1 (Reply 10):
Vmcg is the speed below which control with one engine is not possible; it's mostly due to the size of the rudder and vertical stabilizer, because with an engine out and asymmetric thrust, a large rudder correction is required to maintain straight flight.

Close but not quite. There are two speeds VMCG and VMCA. VMCG is minimum control speed ground which is the minimum speed at which you can maintain directional control with full thrust set on the asymmetrical side. VMCA is minimum control speed air which is again the minimum speed at which you can have full asymmetrical thrust set and maintain directional control. IIRC it's full rudder and 1/2 lateral control.

Quoting Bri2k1 (Reply 10):
ALL airliners can take off with one engine failed, and continue to climb, too

Again, you're partially correct. The statement is true if you're talking about an engine failure at V1. If you have an engine failure at 80 KIAS, then you're not going to have the performance available to continue.
Fly fast, live slow
 
bri2k1
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 2:30 pm

Good point on the difference between VMCG and VMCA. You give a much better explanation than I did.

As far as the other question, I think it depends on runway length. If one engine can propel you from V1 to takeoff and beyond, why couldn't it propel you from a stop? You might consume more ground doing it, but I bet you could eventually do it on a long enough runway.
Position and hold
 
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HAWK21M
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 2:43 pm

Quoting LeDragon (Thread starter):
if an engine fail after the plane reach V1, would the pilots keep on and take off

After V1 you have to T/O.

Quoting LeDragon (Thread starter):
since every airplane have some extra power to face bad condition, would it be possible, as a test without any passenger, to take off with only one engine

Im sure Tests may have been conducted by the Manufacturer prior to Certification.
The Current Engines on the B777s can develop approx 115,000 lbs of thrust & thats quite a lot.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
MD-90
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 3:50 pm

You might could do it at Edwards AFB. It'd probably need to be an empty airplane with only a few hours of fuel.
 
PhilSquares
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 4:22 pm

Quoting Bri2k1 (Reply 12):
As far as the other question, I think it depends on runway length. If one engine can propel you from V1 to takeoff and beyond, why couldn't it propel you from a stop? You might consume more ground doing it, but I bet you could eventually do it on a long enough runway.

Because V1 is a higher speed than VMCG, so you have directional control on the ground and can therefore accelerate to V2 which is also higher than VMCA
Fly fast, live slow
 
bri2k1
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RE: Could A 777 Take Off With One Engine Only?

Wed Dec 28, 2005 11:39 pm

Good point. Obviously I haven't started multiengine training yet  Smile Thanks!
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