Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Serenity on April 02, 2016, 09:27:45 PM
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... so, why is almost ever private jet ever made designed with the engines mounted to the fuselage at the base of the tail, rather than any other possible configuration?
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My guess is that it is probably the most cost effective.
If they were mounted under the wings, a private jet doesn't have as much clearance between the intake and the ground as if they are mounted on the tail.
If they were mounted as part of the wing or fuselage, they would be a lot more expensive to manufacture and would eat up space used for seating or fuel.
Just speculation on my part.
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I think it is the most cost effective way to reduce cabin noise, and the reduced height of the aircraft profile means the wings are closer to the ground with less room for engines.
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... so, why is almost ever private jet ever made designed with the engines mounted to the fuselage at the base of the tail, rather than any other possible configuration?
They tried to install them in the nose.
That did not end well I can tell you.
:uhoh
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I guess the advantage is that with the engines on the tail the wing can be placed below the fueslage so that it does not take up a lot of space in the cabin.
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Greater CL-max due to elimination of wing-pylon and exhaust-flaps interference. Less drag, particularly in the critical take-off climb phase, due to eliminating wing-pylon interference. Less asymmetric yaw after engine failure with engines close to the fuselage. Lower fuselage height permitting shorter landing gear and airstair lengths. Last but not least - it may be the fashion.
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I think it is the most cost effective way to reduce cabin noise
Winner winner, chicken dinner. :D
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Random airplane answer: An enclosed cockpit allows pressurization and oxygenation which in turn allows for higher altitudes to be reached.
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Greater CL-max due to elimination of wing-pylon and exhaust-flaps interference. Less drag, particularly in the critical take-off climb phase, due to eliminating wing-pylon interference. Less asymmetric yaw after engine failure with engines close to the fuselage. Lower fuselage height permitting shorter landing gear and airstair lengths. Last but not least - it may be the fashion.
Bam! Brilliant, thank you!
Random airplane answer: An enclosed cockpit allows pressurization and oxygenation which in turn allows for higher altitudes to be reached.
This answer wins the thread!
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You're welcome. If it helps you win an argument/bet, you owe me a challenge coin or something...
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You're welcome. If it helps you win an argument/bet, you owe me a challenge coin or something...
lol deal!
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... so, why is almost ever private jet ever made designed with the engines mounted to the fuselage at the base of the tail, rather than any other possible configuration?
:airplane: The reason for mounting engines where they do on private jets is nothing else but "center line thrust". One of the problems of small jets is called VMC! That is "minimum control airspeed"! With the engines mounted on the wings, they are much further apart as related to the center line of the aircraft, there fore, the VMC will be much higher on aircraft with wing mounted engines, vs center line mounted engines.
There is a requirement by the FAA, when certifying aircraft for flight, that they meet what is known as a "balanced field length". What this is, a jet acierates to a certain speed, loses one engine, then how far does it take to stop the aircraft!
This is very important as a lot of small towns and counties have runways at their airport, where a lot of jets CANNOT operate from due to this requirement, so manufactures of jet aircraft for "corporate" use, try to balance out load carrying ability, range and "balanced field length", of which VMC speed is very, very important.
And last but not least is the noise factor, which with wing mounted engines is much higher than center line engines mounted on the rear of the aircraft.
There are a lot of other reasons for mounting center line thrust engines, center of gravity considerations, length of fuselage and even how high they want the height of the interior of the passenger cabin, for reasons of passenger comfort.
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I don't believe that the pylons used to mount engines to the rear of the plane have zero drag.
(http://www.smartcockpit.com/images/xl/CHALLENGER-604.jpg)
The later 737 marks had almost done away with pylon drag.
(http://adg.stanford.edu/aa241/propulsion/images/image154.gif)
One of the main reasons for rear fuselage mounted engines is that they allow the plane to be closer to the ground meaning your gear is a lot less in length, weight, and complexity among other things.
The asymmetric yaw is less on rear fuselage mounted engines if you have one that is failed than with wing mounted engines.
Having an engine pod on the wing does reduce lift except during usage of "blown flaps"....if so equipped.
One of the reasons to have wing mounted engines is that the wing's bending moment is less since the weight of the engine is incorported into the wing instead of the fuselage.
There are a lot of compromises with tail design when mounting engines back there such as horizontal stabilizer/elevator placement and the possibility that engines could blank the airflow to this important control structure as well as the wings also blanking the flow at certain angles of attack that might not affect a plane with wing mounted engines.
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Honda seems to have found the solution.
http://www.hondajet.com/hondajet/innovations
(http://www.hondajet.com/images/galleries/exterior/jets-in-formation.jpg)
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I don't believe that the pylons used to mount engines to the rear of the plane have zero drag.
You need to reread what I wrote. I didn't even mention pylon drag.
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What makes this question random?
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What makes this question random?
There wasn't any particular reason for it, I was just watching TV one day, and it occurred to me I've never seen a private jet in ANY other configuration, despite there being all manner of piston plane configurations...