Aces High Bulletin Board
General Forums => Custom Skins => Topic started by: Kev367th on February 22, 2006, 11:58:29 AM
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New rivet techique.
Rather than do the actual rivets themselves, trying to get the slight deformation that occurs around each rivet as its put it.
New, more subtle (ignore panel lines etc)
(http://www.cyberonic.com/~kreed/test.jpg)
Compare to old (rivets on wingtips easily seen)
(http://www.cyberonic.com/~kreed/saafvb.jpg)
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Heres the original double size -
More visible, but on color reduction to 256 becomes a lot more subtle.
(http://www.cyberonic.com/~kreed/test2.jpg)
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i really like it. looks very nice, and the paint scheme comes across more boldly. i think it looks really nice, good job kev;)
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Damn, this is hard to make any clear calls about. OT1H, the look of the new version, as in how well you see the rivet, is a very good rendition of how flush rivets look through pretty fresh paint. OTOH, they also look way too big, being several pixels wide.
I think you're under a msconception as to how riveting works in the aircraft industry. It does NOT deform the skin, at least not intentionally. If it does, then it's a problem and has to be reworked or scrapped.
When you build up a skin panel (consisting of the skin itself and any attached structural members such as stringers), the skin itself is always pre-bent to the curve of that part of the airplane, so it retains that shape naturally. This is not only so it ends up with the aerodynamic shape the designer called for, but also to prevent building stress into the assembly. That's a bad thing because it puts the structure already part-way to its breaking point before the plane leaves the factory, so it can't take as much load as designed in flight. Also, it will try to return to its natural shape, resulting in the structure twisting out of true, ruining aerodynamics and making the plane fly crooked.
For this reason, the outer surface of the skin trumps everything. With the all the parts in the jig, before drilling any holes you have to check for gaps between the structural parts and the inner surface of the skin. If any exist, you have to build shims to fill them. OTOH, if any of the underlying parts stick up too high, you have to file them off or something. IOW, the structure is ALWAYS built to the skin, and the skin is NEVER deformed onto the structure.
Once you've got the parts fitted correctly, you drill the holes, countersink for flush rivets, disassemble, debur, and then reassemble with sealant between the faying surfaces. Only now are you ready to install the rivets.
Rivets are not "shot" into the plane as if by a nail gun, despite "shooting rivets" being the term used in the industry. Instead, rivets are inserted by hand into their holes. They go in quite easily because rivets are designed to be slightly smaller than their holes. This is because they will be "bucked" into final form, which causes their shanks to expand and fill the hole.
The vast bulk of aircraft rivets are bucked in (although this is still called "shooting"). Bucking rivets is a 2-man operation. 1 guy applies a rivet gun (it looks like a drill but it's really a small air-powered jackhammer) to the head and the other guy holds a bucking bar (just a conveniently sized slab of steel) up tight against the tail end. The combined action of the gun hammering the immobile rivet's head, and the pressure of the bucking bar on the other end, expands the rivet's shank to fill its hole and mashes the tail into a thick, button-shaped disc called a buck-head.
During this process, the only thing having pressure applied to it is the rivet. The skin itself has nowhere to go, because the structure is tight up against it, and is itself held firmly in the jig, which is bolted to the factory floor. Thus, you get a nicely bucked rivet without any skin deformation. And the head is absolutly flush with the skin, another thing the inspectors check for on the line. So there's no deformation at all on or around a flush rivet.
NOTE: some rivets are squeezed instead of bucked, but in general that only works on very small assemblies, no bigger than the throat of the squeeze gun. The principle is the same as bucking, but it can be done by 1 man.
That all said, there was (and is) a different method for making flush fasteners. Instead of countersinking the holes, the skin itself is actually deformed by a dimpling machine. It could only be done on very thin metal, and caused a number of problems elsewhere. For instance, the bottom of the dimple stuck down below the inner skin surface, so you either had to have corresponding dimples in the underlying structure, or you had to do a LOT of shimming. Also, the dimpling process tends to deform the panel somewhat, making it very hard to get a good fit on the underlying structure. And the rivet isn't nearly as flush when you get done, anyway. As such, dimpling has only really been used for relatively flat panels, like on wings, where quality isn't as important as quantity and speedy construction. It appears that the Germans started using dimpling towards the end of the war, which is why their rivets are so prominent even when painted over. However, I don't think any Allied combat plane ever used it. It's just not a good option for high-performance planes.
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I did a lot of experimenting with differing opacities on my rivet layers. The "new" one you posted simply looks like a lower opacity level. The "old" one you posted simply looks like a higher opacity. It's a judgment call. I prefer more subtle rivets. I've compromised, however, because other folks want to see them more than I do.
So basically go with what you like. I don't know if it makes it "look more realistic" -- but I like subtle rivets, and your "new" one has them.
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I know Bullethead.
I spent many years (10+) working on rotary and fixed wing aircraft.
IRL you wouldn't see any rivets from the kind of distances we view from, even from within the cockpit.
But, a skin without any rivets just doesn't look right, its the old what people expect to see vs what can actually be seen.
Had some occasions where the rivetting process definately caused a deformation of the panel around the rivet. One that springs to mind was adding doublers to a Lynx engine bay firewall during a Navy Lynx upgrade program.
Problem is how to simulate rivets on skins.
My new way doesnt actually have a rivet at the center its just a slight highlight and lowlight around the area where the rivet would be.
Gave me an idea though, I had been pushing the highlight diagonally one way, maybe if I leave it in its original position it would look better.
The original skin pic is actually enlarged double size, when reduced to 256 in 1024x1024 the effect is more subtle.
Tried doing complete uppers -
I think its look better than original SAAF Vb pic earlier. (ignore chips around roundel)
(http://www.cyberonic.com/~kreed/saafvb2.jpg)
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Kev367th said:
I know Bullethead. I spent many years (10+) working on rotary and fixed wing aircraft.
Who'd you work for? I worked for Vought (before it became Northrop-Grumman) building new stuff and for what was once a division of Chrysler, doing mod/repair. Given the incestuous, wife-swapping nature of the aviation industry, we might have been co-workers at some point ;).
Had some occasions where the rivetting process definately caused a deformation of the panel around the rivet. One that springs to mind was adding doublers to a Lynx engine bay firewall during a Navy Lynx upgrade program.
Yeah, but that was a helo, where drag and all isn't a real problem because none go fast enough. You could use domeheads on a helo (which many have, due to their tissue-paper skins not being thick enough to countersink) and it wouldn't make any difference. I think the sexier modern helos just have countersunk fasteners for eye appeal, not for any practical purpose. If a SPAD (the WW1, not the Viet Nam, type) got into knife range with a moden combat helo, I'd give the SPAD at least even odds :D.
Problem is how to simulate rivets on skins. My new way doesnt actually have a rivet at the center its just a slight highlight and lowlight around the area where the rivet would be.
Well, as you know from the real thing, at best with a countersunk rivet under paint, you just get a slightly different color of the paint, due to it being a flat spot in the middle of a curve. I've tried just using whitish 1-pixel dots with the opacity turned low, and that looks OK in places. Problem is, they don't react to light like the real thing, so only look good in certain areas where the curve is right. Elsewhere, they look too shiny.
Be all that as it may, I have some actual constructive criticism of your rivets here. On many spits, they usually had domeheads along the main fuselage longeron, which runs along the panel line 1/2way down the fuselage. Actually, a double row of them until back by the roundel, where the panel line has that joggle in it, which marks where the longeron stopped being so wide. They also had domeheads in the vertical line at the rear of the sliding part of the canopy, down to this longeron, on both sides (it would be just behind the entry door on the left side). Many spits also had domeheads on some or all other longitudinal panel lines. They took the time to check this and found it didn't add anything to drag to have the fuselage longitudinal lines be domeheads, and that of course saved them a lot of time on the factory floor.l
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Naw -
9 years British Army working on Lynx, Gazelle, and Islander. (Airframes and Engines)
We only had two aircraft trades -
'Blackies' - Airframes and engines.
'Greenies' - Wiggly amp crap.
Then 4-5 years contracting at various places -
KLM Amsterdam (737, 747)
FLS Stansted (727, 737, Airbus)
Dornier (Do223 / 323 / little bit on Citations including Michael Schumachers)
Westlands (Navy Lynx upgrades)
Best one was a privately owned 727 at Stanstead - Gold fittings, carpets, rugs, leather couch/ seats etc in 3/4 main cabin.
Rear 1/4 was were the 'flight attendents' sat, it was totally standard lol.
Cockpit even had carpeting though.
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Kev fantastic!!! I love it. it looks like actual aircraft skin with flush rivets! hehe
thats the right mentality to have is not making the skin the way the tradition says it should be with unrealistic tank rivets all over it.
making it look like a real aiplane is much better hehe.
not to many others here are willing to even contemplate the logic of this. there are a few and I am glad you are one of them!
S! kev keep it up :)
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only suggestion or comment I can make is make all the 3d effects from the pilots cockpit perspective so it looks best in the game. looking good offline in external view is cool too but it gets viewed the most online in cockpit looking at the wings and nose and tail.
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I usually make the shadows "global", because to me I'm mostly examining the craft from exterior mode, or in the skin viewer, or on other planes, so from the outside perspective I wanted global shadows.
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Well it looks like most prefer it, so I'm going to keep on doing them that way.
Thanks for suggestions and encouragement.
Nearly got it finished - Oh how the MA needs another desert map.
(http://www.cyberonic.com/~kreed/saafvb3.jpg)
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:aok
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Kev367th said:
Best one was a privately owned 727 at Stanstead - Gold fittings, carpets, rugs, leather couch/ seats etc in 3/4 main cabin. Rear 1/4 was were the 'flight attendents' sat, it was totally standard lol. Cockpit even had carpeting though.
When I worked at the Chrysler place, we made planes like that, totally pimping out airliners for rich dudes. Our biggest customer was the Sultan of Brunei and his family, who had us customize a whole fleet of various things. He started out with a 727 pretty much as you describe, but eventually decided it wasn't new and sexy enough so gave it to one of his sons and had us do a 747-400 for him. Then the son outgrew the 727 and had us do a 767 for him, and then the Sultan's brother had us do him one of those 4-engined Airbus jobs. We finished the 747 in time for the Mecca pilgrimage season, and the Sultan took it there to show off to his OPEC buddies, some of whom placed orders with us to make them even cooler rides to 1-up the Sultan. I left the company before we did any of them, however.
These planes were sickening, over-the-top flying palaces with absolutely no expense spared. The 747 in particular. Imagine an Arabian Nights palace with every toilet bowl, bidet, sink, drawer knob, water tap, air conditioner button, etc., made of solid gold. Huge reclining, massaging, gyro-stabilized chairs, skinned in exotic leathers from endangered species, with gold buttons to control all the window blinds, the TVs, communications, etc., in the arm rests. Shag carpet made of silk several inches thick embroidered in arabescques with gold thread. Exquisite birds-eye maple panelling on every cabinet and most walls, carefully selected and stained to look just like marble of various colors. And besides the luxury appointments, the thing was rigged out as a full head-of-state ride, with large conference rooms and all the associated comm gear. AND we put in all kinds of ECM and anti-missile systems, surveillance camera systems inside and out, etc. The Sultan spent more on pimping this 2nd-hand 747 (he got it from Lufthansa) than Uncle Sam did on a brand new B-2 Stealth Bomber.
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Kev367th said:
Nearly got it finished
Looks great, except IMHO you really need to make the longitudinal rivet lines much more prominent compared to the others, especially along the main longitudinal. Those were domeheads on almost all spits.
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Tried it on anothe Vb I'm playing with, is this what you mean?
(http://www.cyberonic.com/~kreed/rcaf2.jpg)
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Kev367th said:
Tried it on anothe Vb I'm playing with, is this what you mean?
Damn, those are some nice domes.. OH, the RIVETS. Sorry, I was looking too far forward there :).
Anyway, yup, those are the rivets I was referring to. But IMHO instead of making them as what look to be wider versions of the other rivets, you should darken them so they remain of small diameter, but are more visible, like they're casting little shadows.
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Its very nice work kev
:aok