| Author | Message | ||
     Koz5150 |
This image is just disturbing, but kinda cool.  http://www.gizmag.com/787-dreamliner-completes-ultimate-load-test/14663/ | ||
| P47b |
Not to disturbing for me. I'm interested on when it's going to fail. I would love to do that. | ||
| Buellkowski |
IIRC, in normal flight the 787's wingtips will be above the fuselage. It'll definitely be a flappy sorta bird. | ||
| Aesquire |
I wonder, after the test to spec. will they go to destruction? A lot of money for that, but it gives real interesting data. http://science.slashdot.org/article.pl?sid=07/06/2 7/1723251 I have been involved in static testing wings on hang gliders. ( I didn't have to do the math, I just carried sand bags) Without a giant pneumatic press setup like Boeing has, we did it the old fashioned way, hanging the airframe upside down ( easier in a 70 lb. glider than a 5000 lb. propjet ) and loading sandbags on the wings until failure. You got real slow & careful as the mass got bigger, and wire thimbles and tubing changed shape. It is more than scary watching stuff bend that you depend on for flight. The B-47 had wings that flexed 35 feet between +/- loading. The LABS ( loft bombing ) maneuver must have been a hoot to do, but stress cracks led to a major recall & repair cycle at the height of the cold war. They quit doing LABS in the B-47, but it continued as a way to avoid the blast & defenses for ( much smaller ) strike aircraft through the Vietnam war. Though seldom used with conventional bombs in Vietnam, it was still trained for...I don't think F-16 jocks do it, as they came up with the "lay down" technique where a parachute slowed bomb is used in a low high speed pass with a brief climb before the target, and a screaming dive away. ( at least I would be noisy doing such a maneuver....) http://www.youtube.com/watch?v=mqIJL8lx00o | ||
| Gregtonn |
Wing flexing is a good thing. If wings didn't flex air turbulence would make a hard-tail HD ride seem comfy and the wings would be torn from the fuselage. G | ||
| Skinstains |
Smoke and mirrors boys. Next thing you know they'll be trying to tell us that we can put a man on the moon... | ||
| Ourdee |
F-111-F did loft bombing. | ||
| Kilroy |
Which wing is stronger, a wing that has an engine suspended underneath, or one that doesn't? | ||
| P47b |
The wing is primarily the same for each aircraft. Depending on what the aircraft is designed for. It is the root of the wing that changes to carry the engine. With the root of the wing counted, the engine suspended underneath would be stronger. | ||
| Kilroy |
Doesn't the weight of the suspended engine counteract some of the lifting force acting in the opposite direction, resulting in a wing that in total needs to be "less strong"? That is what I had been told and wondered if anyone here can confirm / refute. | ||
| Aesquire |
By distributing mass along the wing, you reduce the bending force on the wing. All the weight isn't in the middle with wing mounted engines. Also, getting them further away from the cabin reduces noise inside. The pylons they hang the engines from also stiffens the wing in twisting, and blocks spanwise airflow ( from the wing root to the tip, a problem on swept wings ) Bad part of wing mounted engines is the loss of power on one side in an engine failure makes the plane want to turn, and you have to correct with rudder which adds drag. The major difference between a single engine pilots training and a multi-rating is dealing with the asymmetric thrust. It can be very bad news on takeoff if the increase in drag from cranking the rudder over ( plus flaps & gear drag ) exceeds the thrust and you go down, instead of up..... Buts it's all in the design, the DC-9 with tail mounted engines, has just as strong a wing because it's built that way, and the asymmetric thrust is way less, amking an engine failure less of a hassle. But it's noisier inside in the back of the cabin, etc. It's all in what compromises you make. ( the above is a massive oversimplification ) | ||
| P47b |
Less strong? From all the aircraft I have worked on I would say no. The wings are are all built to a same standard to the aircraft design standard. The Root of the wing is what is taking the stress of the engine and wing together. Were you thinking Less Stiff? Flex in any aircrafts is it's saving grace. (Message edited by p47b on April 04, 2010) | ||
| Aesquire |
DC-9, 787, all commercial planes are built to be at least as strong. They measure it by how many "g"'s you can pull on the whole plane. In testing it's common to have the seat mounts fail long before the airframe. The FAA has standards. While some planes are certainly "stronger" than others, the guys that design them know that making a plane stronger makes it heavier. A XB would be stronger if the frame was solid instead of hollow, but it wouldn't do what it does as well, same with planes. Flex is better than brittle. Brittle breaks. It's been a while but as I recall utility class planes run +6/-4 g's. That's like having 5 guys your size sitting on you. Although a F-16 can pull 9 g's ( limited by the computers ) and some can pull up to 11..... people don't work that good at that load. It's actually hard to pull more than 2, 3 g's in a non aerobatic plane, I doubt I've ever pulled more than 3 in a glider. (4 in aerobatic moves, maybe...) I could, but why? The extra load causes more drag & you just hit the ground quicker.... max g's in a glider are usually vertical bank moves that would be considered aerobatic in most powered planes, but the tumbling, spinning stuff is usually avoided because you are powered by gravity, and She's a harsh Mistress. In a Piper Cub you give it more gas, in a glider, you go downhill. More. Then you run out. | ||
| Boogiman1981 |
would like to be nearby when if it fails in that rig. wonder though would it be a sudden catastrophic failure of one tear/crack leading to another extended slomo failure?? | ||
| Toona |
Not the video I have seen before. I'm thinking it might have been from a local TV station??? | ||
| A_s_r |
Cool Stuff! |
