JF-17/FC-1 Fighter Aircraft thread

Here is an excellent article on why rivetting



"aluminum becomes weaker when exposed to heat, including the heat from welding, so most aerospace manufacturing companies prefer to connect joints using rivets".

"The greatest benefit of using riveted joints in an aircraft is that they are stronger and more durable than welded joints. When two components are welded together, only the exterior of the components are joined together. On the other hand, using a rivet connects the two components from the inside, thus allowing for a stronger and more durable joint. This is particularly important for aircraft, as flying 550 mph at 30,000 feet above sea level places severe stress on the aircraft’s joints".

"Riveted joints are also easier to inspect than welded joints. It only takes a quick visual inspection of a riveted joint to ensure that the two connected components are secure. With a welded joint, a machine or device must be used to test the joined components. There’s no easy or effective way to perform a visual inspection of a welded joint. Therefore, aerospace manufacturing companies use riveted joints to simplify both the production and maintenance process of their aircraft".

Chinese ejection seat factory documentary reveals the seats on jf17b.

OrientalGamer said:

Chinese ejection seat factory documentary reveals the seats on jf17b.
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Isn't canopy supposed to open before the seats are ejected???

Haris Ali said:

Isn't canopy supposed to open before the seats are ejected???

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Hi,

Not necessarily---. It depends if that option is provided---. In this case the glass explodes outwards and the seat is following thru---or maybe the upwards motion of the seat breaks thru the glass.

I don't know if there is a det cord lined up in the glass---.

Haris Ali said:

Isn't canopy supposed to open before the seats are ejected???

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No. It's like this on many fighters... the canopy detonates and/or the seat penetrates through the shattered canopy.

MastanKhan said:

Here is an excellent article on why rivetting

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"aluminum becomes weaker when exposed to heat, including the heat from welding, so most aerospace manufacturing companies prefer to connect joints using rivets".

"The greatest benefit of using riveted joints in an aircraft is that they are stronger and more durable than welded joints. When two components are welded together, only the exterior of the components are joined together. On the other hand, using a rivet connects the two components from the inside, thus allowing for a stronger and more durable joint. This is particularly important for aircraft, as flying 550 mph at 30,000 feet above sea level places severe stress on the aircraft’s joints".

"Riveted joints are also easier to inspect than welded joints. It only takes a quick visual inspection of a riveted joint to ensure that the two connected components are secure. With a welded joint, a machine or device must be used to test the joined components. There’s no easy or effective way to perform a visual inspection of a welded joint. Therefore, aerospace manufacturing companies use riveted joints to simplify both the production and maintenance process of their aircraft".

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Good afternoon MastanKhan, I'm going to take exception not to your post, but to Monroe Aerospace's contention that riveted joints are stronger/superior to welded joints... now the General Aviation aircraft that I fly are indeed "riveted" rather than welded....

But, Monroe Aerospace sells aircraft fasteners, cherry rivets, pop rivets, dzus type fasteners,,,, there are a lot of reasons to use rivets to join thin aluminum sheets for skin, or shaped and formed ribs, bulkheads, formers, stringers etc, etc, etc...... but strength is NOT one of them....

Properly welded aluminum or titanium structure in aircraft remain the strongest possible means of joining aircraft structures, surpassing adhesive bonding and riveting, and while many here love composites, composites may be inferior in certain applications of aircraft structure..

Aircraft skins are riveted/bonded due to the fact that they are very thin, and heat is indeed an issue when it comes to structural integrity. On aircraft skins riveting/bonding, or preferably a combination of the two are indeed very effective and strong and provide the optimal mating of similar surfaces.

but on aircraft structure/airframing, welding remains superior providing a molecular bond between those two pieces of metal, and in fact the welded joints are often much stronger than the parent materials being joined.

MastanKhan said:

Hi,

There is a reason that aircraft are riveted and not welded ( maybe in a few places ).

Even the F22 is riveted---and the super jumbo airbus 380 as well and all other aircraft---.

Only cars has have welded joints.

You cannot use weld on air crafts when you need rivets---. Aluminum does not like to be welded---.

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Actually the support structure of the F-22 is welded titanium, just as it is on the F-35, skins may be bonded/riveted to that underlying support structure...

Air Force Brat said:

Actually the support structure of the F-22 is welded titanium, just as it is on the F-35, skins may be bonded/riveted to that underlying support structure...

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Hi,

Thank you for the post---. We are on the same page---. The riveted joints would be skin to the frame.

Hi,

Hand drilled holes---not a bad job of riveting---.

That's a fine riveting job, if you have your structure and your skin predrilled, when you begin to set your rivets, you may pull the skin away from the pre-drilled holes in the structure, that can cause the skin to buckle and not lay flat against the structure. If you have to ream out the rivet holes, you will end up with more clearance between the hole and the rivet. Ideally the rivet fits into the hole with almost an interference fit, a little tension going in, and when you place the bucking bar behind the rivet, you have a nice clean head peened on, that pulls the rivet up snug and fills the hole neatly with minimal clearance all the way around.

Riveting is an art, I can't do it, but I can tell you if the gent who did knows what he's doing, lol. Skins all almost always riveted or bonded to the underlying structure, sometime skins are "flush riveted" and butt up against one another,sometime they over lap one another, depending on the area being skinned as well as the complexity of the aircraft being skinned...

My little brother has a Cessna Cardinal, a beautiful airplane, but an airplane that is know for a less than pristine finish, rivet lines meandering around, and even skins that don't lay very nice... The 1968 Cardinal had a cantilever "laminar flow" wing, very clean with a sharp leading edge, with only 150 hp, you could get in trouble, and as you increased angle of attack, the laminar flow wing would "load up" and get draggy, not good for a generation of Cessna 172 pilots who were used to a much more forgiving wing. In addition the Cardinal wing is probably a foot further aft, creating the need for a stabilator to increase pitch force to allow for a smooth flare, but the stabilator itself would suddenly stall, allowing the nose to "fall through" and taking out a great many nose gears and firewalls... Cessna fixed their airplane, but it was a LOT of work done for free, under a program know as the "Cardinal Rule"

MastanKhan said:

Hi,

Hand drilled holes---not a bad job of riveting---.

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In fact those large round head rivets are "Cherry Max" type "pulled rivets" for riveting "blind" holes, in other words you can't get a "bucking bar" behind it, so you use the large headed "Cherry Max" pulled rivets, there is a very strong steel core that "pulls" the back of the rivet into shape from behind... unlike the "flush rivets" you see in the middle of the panel.