J-20 5th Generation Fighter VII
- Thread starter siegecrossbow
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Coming back to this , starting at 4:10 the guy claims that the weapon bay opening combined with canard is less optimal. The reasoning goes the opening weakens the structure against bending and torsion and the canard applies aerodynamic loads, which means having to add additional weight to beef up the structure. This seems reasonable at a first glance but having thought through the forces involved, I have reached the opposite conclusion, that canard is actually beneficial to the weapon bay.
It is true that any opening will weaken the chassis but it is a problem for any aircraft with an internal weapon bay like F-22 and F-35 too. The canard applies a force at the front of the aircraft, this would be an issue if you are trying to bend or twist the body. But since you are more likely to be trying to turn the plane by matching the force applied at the front and back, it actually reduces the amount of force needed to be applied at the middle where the opening is located..
It is true that any opening will weaken the chassis but it is a problem for any aircraft with an internal weapon bay like F-22 and F-35 too. The canard applies a force at the front of the aircraft, this would be an issue if you are trying to bend or twist the body. But since you are more likely to be trying to turn the plane by matching the force applied at the front and back, it actually reduces the amount of force needed to be applied at the middle where the opening is located..
I'll be honest, I don't think that video is worth coming back to in the first place.
True, but the argument made in the video was pretty compelling until you get into the details.
It’s not compelling at all because there’s more than one way to design load bearing structures. These airframes are not solid objects but a combination of different struts and hollow shapes. You don’t need to add extra mass to reinforce these structures. You just need to position different structures in different ways to transfer or absorb the expected loads.
Depends on where the centre of gravity is. I really doubt canards position would be allowed to place any major strain at the centre of the weapons bays are located as a result of how the forces applied by the aerodynamic conditions created by canard deflection.
A conventional layout 5th gen fighter like F-22 does not "pivot" the aircraft along the axis that is at where the horizontal stabilisers are. On the F-22, it would probably be a bit further along the fuselage between weapons bays and mid section of engines. Just like with J-20's canards, the F-22's horizontal stabilisers themselves would be carrying and transferring the loads appropriately and that includes the internal forces in the section itself.
I reckon J-20's is probably around the end of the weapons bays or between them and the front section of engines. But he is right that the structure absolutely would require beefing up in order to carry those forces to desired locations and this would be designed with a particular desired CoG of design. So he's not wrong in saying that the engineers would have needed to find ways to appropriately support this particular design and that usually would involve some weight penalties although honestly this probably isn't significant at all to the point of not worth mentioning except to say that it is certainly required.
A conventional layout 5th gen fighter like F-22 does not "pivot" the aircraft along the axis that is at where the horizontal stabilisers are. On the F-22, it would probably be a bit further along the fuselage between weapons bays and mid section of engines. Just like with J-20's canards, the F-22's horizontal stabilisers themselves would be carrying and transferring the loads appropriately and that includes the internal forces in the section itself.
I reckon J-20's is probably around the end of the weapons bays or between them and the front section of engines. But he is right that the structure absolutely would require beefing up in order to carry those forces to desired locations and this would be designed with a particular desired CoG of design. So he's not wrong in saying that the engineers would have needed to find ways to appropriately support this particular design and that usually would involve some weight penalties although honestly this probably isn't significant at all to the point of not worth mentioning except to say that it is certainly required.
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