China's transport, tanker & heavy lift aircraft

by78

General
She comes and she goes...

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sanblvd

Junior Member
Registered Member
Does the landing gear compartment has to stick out like that? Why doesn't passenger jet don't look like this?
 

N00813

Junior Member
Registered Member
Does the landing gear compartment has to stick out like that? Why doesn't passenger jet don't look like this?

Passenger-jets are concerned about fuel-economy, which is negatively affected by the extra drag caused by the landing-gear compartments.

The Y-20 has the landing-gear compartments on the outside probably because otherwise the landing gear will poke into the interior cargo space, so instead of a "flat space" inside it will have 2 bumps on each side. This limits what you can transport (e.g. MBTs cannot go all the way into the cargo compartment due to the bumps, and if you tie it down next to the loading ramp, this will hugely impact the centre of gravity of the plane, which may cause flight problems).
 

Mike North

New Member
Registered Member
Does the landing gear compartment has to stick out like that? Why doesn't passenger jet don't look like this?
Passenger jets have fuel tanks under the seating compartment in the hold and landing gear in the wings. If the wing is over the fuselage the landing gear would be really long and too heavy. The bulges that you see hold lots of fuel and the landing gear
 

asif iqbal

Lieutenant General
Wasn't it already speculated though that some prototypes were converted into operational units ?

Not a compete surprise in that case
 

delft

Brigadier
Does the landing gear compartment has to stick out like that? Why doesn't passenger jet don't look like this?
This is a subject close to my heart. The other two answers are true but not the whole story. The first to notice is the matter of high wing or low wing.
Most passenger aircraft have low wings among other reasons because the fuselage is higher in the water if you get into the drink which happens very rarely nowadays but we all remember that landing into the Hudson after a double engine failure. It enables you to mount the main undercarriage members further apart than the diameter of the fuselage without anything sticking out. In an aircraft with swept wings the undercarriage fits behind the main wing box which can be filled with fuel. But even in the Boeing 747 you see the main gear stowage exceeding the fusion of fuselage and wing.
But in smaller aircraft the fuselage gets to far above the ground because of the diameter of the diameter of the high bypass engines and military cargo aircraft have their own reasons. The last also often use large low pressure tires that cannot be fitted below the cargo floor. The distance between left and right main wheel is also important. Even so the drag of these large bulges is often much less than the drag due to the loading ramp.
And even this is only just scratching the surface.
 
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