Qs about multi

jetman

New Member
Hi guys i got some Qs about multiengines
From the Duchess 76 POH
Vmc 65
Vsse 71
Vr 75
Vxse 85
1] Is V1 [desicion speed] Vr 75 or Vxse 85?
2] If engine fails right after Vr 75 should the plane be ascelerated to Vsse 85 [ Vyse is also 85] on ground efect
?
3]What is the dif . between Vmc and Vsse [safe se speed]
Tnx a lot
 

Buzo

Well-Known Member
The Duchess doesn't have a V1, or V2 speed. Only airplanes certified over I think 6,000 gross will have V1, or V2. In light twins they do not have to demonstrate a single engine climb.

Vsse is the slowest speed you want to intentionally shut down an engine during training, it has nothing to do with V1, Vr, or V2.
 

FL270

New Member
[ QUOTE ]
1] Is V1 [desicion speed] Vr 75 or Vxse 85?

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There is no V1 in the Duchess. If you lose an engine prior to rotation (or even shortly thereafter) close both throttles and land/stop straight ahead.
[ QUOTE ]
2] If engine fails right after Vr 75 should the plane be ascelerated to Vsse 85 [ Vyse is also 85] on ground effect?

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If there is enough flat area (runway/clearway/golf course/whatever) ahead of you to accelerate in ground effect, there is enough flat area to land. You should be closing both throttles at this point and landing straight ahead. You don't want to try to fly a light twin from 30' with an engine failure.
[ QUOTE ]
3]What is the dif . between Vmc and Vsse [safe se speed]

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Vmc is the minimum speed at which directional control can be maintained with an engine inoperative. Vsse is used in simulated engine-out operations for training, and is the manufacturer's minimum recommended speed for intentional engine-out operations in the airplane.

Hope this helps. Felt good to shake out my MEI skills


FL270
 

ERAU_Intern

New Member
Riddle Pilot has no faith in the Duchess. She is a thing of beauty, and will carry your prescious tail anywhere you want her to. But thats ok, because Riddle Pilot was born and raised on the Piper "BRICK" Seminole. He has yet to see the light.
 

Baronman

Well-Known Member
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and will carry your prescious tail anywhere you want her to

[/ QUOTE ]

The Dutch-Ass will carry you just as quick to your favorite crash site!!
 

RiddlePilot

New Member
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But thats ok, because Riddle Pilot was born and raised on the Piper "BRICK" Seminole.

[/ QUOTE ]

*Southern drawl* Flyin' brick? I like that...
 

jetman

New Member
Thank you all for replys

Is there a point in the climb out where if an engine fails IT WOULD BE SAFE to continue?[assuming standard temp and press]
 

Alchemy

Partner, Ally, Friend
Just like in a single, deciding what to do when an engine fails is a judgement call. Do you have enough runway remaining to land and stop? If so, secure the engines and take 'er straight down. This is the most preferrable option. If not, you need to decide very quickly wether you can circle back around for a landing or if you need to put the aircraft down into the closest suitable off-airport landing site.

Read this for more info on light twin single engine performance:

Always Leave Yourself An Out

[ QUOTE ]
Let's get some real-life factors into the single-engine takeoff equation. Suppose, as is usually the case, we begin the takeoff roll about 75 feet from the approach end of the runway and do so without holding the brakes. This could add 475 feet to the handbook figure. Next, suppose we lose the engine at rotation, but it takes us three seconds to recognize the situation and react. (This, by the way, is a very conservative figure.) The reaction time will cost us about 537 feet. Now the total horizontal distance from the beginning of the runway to a point at which the aircraft is 50 feet above the surface (assuming engine loss at rotation) is 6,012 feet, an increase of 20 percent. The 421's sea-level, single-engine climb rate is about 305 fpm. Assuming that we want to get at least 500 feet under us before trying anything fancy like returning for a landing, we must continue more or less straight ahead for one minute and 28 seconds. This climb will cover a horizontal distance of some 16,485 feet bringing the total distance covered from the rotation point to 19,485 feet, or 3.7 miles.

[/ QUOTE ]
 

Tired

New Member
There is no one right answer to that question. Right after liftoff, before gear up I would always abort, even if there is not enough runway to stop. After gear-up you have to make a quick choice, say you're at a couple hundred feet, in most light twins best bet is to go to Vyse, and aim for a flat spot to land just like a single. The worst thing you can do it loose control or Vmc at low alt messing with stuff inside the cockpit.

Now if you have some altitude you'll have time to feather the engine and evaluate if you can maintain altitude or not, and if you are decending, if you'll be able to make it back to the airport.

In a twin don't touch anything in the cockpit except the gear until you get 1000'AGL. And always climb at Vy until you get that 1000'AGL.

Here's a question for you all. Lets say your at Flagstaff, AZ, elevation 7000', and the temp is 35C. Your single engine climb rate is -200FPM, would you takeoff?
 

RiddlePilot

New Member
[ QUOTE ]
Here's a question for you all. Lets say your at Flagstaff, AZ, elevation 7000', and the temp is 35C. Your single engine climb rate is -200FPM, would you takeoff?

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Why wouldn't you? I've taken off out of there plenty of times even in single engine airplanes. You lose an engine there, and you bet you'll be coming down faster than 200 fpm. But as a poster above stated, always leave yourself an out. Coming out of Pulliam's Runway 21, you could potentially put down on I-17.
 

Alchemy

Partner, Ally, Friend
I agree with Tired, and the question about Flagstaff is a good one.

To quote the ASA Multi-Engine Oral Exam Guide

[ QUOTE ]
Is a takeoff advisable if the density altitude at an airport is higher than the single-engine service ceiling?

No. Available alternatives are few since the aircraft would be unable to climb or even maintain altitude in the event of an engine failure on takeoff. Know before you take the runway whether you can maintain control and climb out if you lose an eninge while the gear is still down.

[/ QUOTE ]

Then again, using this logic no one should ever takeoff in a single engine airplane at all.....

Personally, my go/no-go decision at Flagstaff would be based more upon my all engine rate of climb performance, obstacles in the area, my takeoff/landing distance and the runway lengths at Flagstaff rather than my single engine rate of climb figures.
 

averyrm

Well-Known Member
I know this is about a Duchess, but there are some instances where a light twin is able to safely do some SE departures. For example, in an Aztec with two souls on board, full fuel, 5000’ runway (1k elevation) STP, I've actually done a single engine takeoff from brake release to 3000’ (the other engine was "simulated feather" the whole time - ready to go if need be). The DE insisted it be done to prove that the plane could do it. It climbed about 500fpm and besides the lackluster performance and rudder trim, it really wasn't a big deal.

What I'm saying is know your airplane. There are times when using the FAA's guidelines can get you into more trouble then need be. Now I know if I'm at 50ft with no remaining runway and a light load when an engine fails, I can still climb out and circle back.
 

pilot602

If specified, this will replace the title that
[ QUOTE ]
Is there a point in the climb out where if an engine fails IT WOULD BE SAFE to continue?

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Yes.

But you need to know your aircraft, your weight, the current atmospheric conditions and the field elevation.

And I don't know why everyone is saying at this point you need to make a "quick decision" - this decision should have been made before you taxied onto the runway!.

I use, and will teach, blueline is the decision for you. At blueline the gear comes up. Before blueline if an engine fails you land straight ahead regardless of runway available - you can use the standard "20 degrees off course" trick like singles do if there's a building, cliff, etc. that would make landing literally straight ahead dangerous - but the point is you land if your gear is down. If an engine fails after blueline (and the conditions permit) you continue to climb for a go around or continue at your present altitude to a "suitable landing area" - preferably a large flat field, or road, at a lower elevation than the airport.

But this is where knowing the conditions becomes important. If the density altitude, or the field elevation, is above your single engine ceiling you have to land because there is no way you can climb or sustain altitude on one engine. Your weight is important because the lighter you are the higher your SEC goes. The POH will have a way of determinig the SEC at given wieghts. Knowing the aircraft is important because the book may say it will perform but the only way to know if that specific aircraft will do what the book says is to spend time in it.

The key to flying a twin is knowing your outs and making your decisions ahead of time and then sticking to them. It does no good to say "before blueline I'm landing" and then actually doing something like trying for a continued climb.

Twins are no more inherently dangerous than a single, with one exception. Engine failure on takeoff. But you should have already gone through the situation in your head and know, ahead of time, what you're going to do if something goes bad.
 

say_speed

New Member
[ QUOTE ]
I know this is about a Duchess, but there are some instances where a light twin is able to safely do some SE departures. For example, in an Aztec with two souls on board, full fuel, 5000’ runway (1k elevation) STP, I've actually done a single engine takeoff from brake release to 3000’ (the other engine was "simulated feather" the whole time - ready to go if need be). The DE insisted it be done to prove that the plane could do it. It climbed about 500fpm and besides the lackluster performance and rudder trim, it really wasn't a big deal.

What I'm saying is know your airplane. There are times when using the FAA's guidelines can get you into more trouble then need be. Now I know if I'm at 50ft with no remaining runway and a light load when an engine fails, I can still climb out and circle back.


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You have to be the best pilot I have ever seen, or even heard of for that matter...
How did you maintain directional control on the ground full t/o power on one engine and the other one at iddle?? how wide was the runway?? 5000 feet???
I am sorry, but this is the most ridiculous statement I have ever heard...
Give me the name of the DE, what FSDO he reports to, someone needs to do something about this before he kills an innocent student.
 

Buzo

Well-Known Member
[ QUOTE ]
In a twin don't touch anything in the cockpit except the gear until you get 1000'AGL. And always climb at Vy until you get that 1000'AGL. [ QUOTE ]


I am going to disagree with that, you need to get rid of that windmilling prop ASAP. Not only will it give you better performance, it will also reduce your Vmc speed. In a lot of light twins you won't make it to 1,000 feet with the prop windmilling. Even in the 1900 fully loaded we struggle to get 200 fpm with an engine feathered
 

Tired

New Member
[ QUOTE ]
[ QUOTE ]
In a twin don't touch anything in the cockpit except the gear until you get 1000'AGL. And always climb at Vy until you get that 1000'AGL.

[/ QUOTE ]

I am going to disagree with that, you need to get rid of that windmilling prop ASAP. Not only will it give you better performance, it will also reduce your Vmc speed. In a lot of light twins you won't make it to 1,000 feet with the prop windmilling. Even in the 1900 fully loaded we struggle to get 200 fpm with an engine feathered

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I'm sorry, I meant if nothing goes wrong. It you lose an engine you are going to need to get it feathered. However, if nothing is going wrong then no need to touch anything and cause a problem before you get that first 1000 feet.
 

viper548

Well-Known Member
Quote:
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In a twin don't touch anything in the cockpit except the gear until you get 1000'AGL. And always climb at Vy until you get that 1000'AGL.
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If you dont touch anything, you'll never get to 1000 feet. Good luck climbing with a windmilling prop. In a JET, you don't touch anything until 1000 feet.
 

Tired

New Member
[ QUOTE ]
I've actually done a single engine takeoff from brake release to 3000’ (the other engine was "simulated feather" the whole time - ready to go if need be).

[/ QUOTE ]

Present-----------------Future
You =======>>> Smoking Hole
 

viper548

Well-Known Member
Is there a point in the climb out where if an engine fails IT WOULD BE SAFE to continue?[assuming standard temp and press]
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1. When there is not enough runway remaining to land the airplane on, and there are no obsticles to contend with. At some airports with short runways and lots of obsticles there may be a point where a safe takeoff can not be done. What I mean by that is if you lose an engine after TO at 100ft, you can not land on the remaining runway and you can not outclimb the obsticles.
There is also a period of time between Vr and Vyse that is unsafe. Engine failure in a light twin below Vyse will require you lower the nose to accelerate to Vyse( not good if you just lifted off). That's why you should accelerate to blueline ASAP!
 
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