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Hermsgervørden posted:Cross-posting this from the physics thread in ask/tell: I made an observation yesterday, and I couldn't understand what was going on. My family and I were departing Rochester airport, where weather conditions are best explained by analogy to Hoth as far as my California mind is concerned, and our plane (Embraer 175) had to undergo a deicing procedure before we could flee the frozen Northeast. My daughter and I were seated behind the wing, and we got a great view of the anti-ice fluid streaming off the trailing edge as we took off. But I noticed something really surprising (to me) on the aileron. A pool of green anti-ice fluid persisted on the back half of the top surface of the aileron well after takeoff which as I watched changed from a mostly flat pool of fluid into a standing wave, maybe 3-6 inches tall, almost like a mohawk. It hung around for maybe a minute or two after takeoff. I could not take a picture because my daughter was already very engaged with my phone. Can anyone explain what was going on there? It definitely did not freeze. I'm not sure what exactly the fluid was, the plane was sprayed twice, first with orange fluid, then with green fluid. The green stuff was still all over the wing when we started the take-off roll. It was dancing and rippling and waving. As far as I could tell, it sort of dripped away upward, perpendicular to the top surface of the aileron. I'd point out that the fluid only acted strangely on the aileron, on the wing surface on either side, and the flaps closer to the wing root, the anti-ice fluid just streamed off as I expected, like rain off a car window. So the two types of deicing fluid are different properties and viscosities, the orange one literally sticks around when all the green stuff has blown off. At a guess I'd say what you were seeing was probably the where the boundary layer of air across the top surface of the wing stops being laminar and becomes turbulent. As these rolling vortices start forming at the trailing edge they would start to lift up the viscous deicing fluid and draw it in to a little wave. The reason I'd posit for you only seeing the effect on the aileron is that the wing is probably designed that way, so that these aerodynamic effects happen deliberately over the ailerons.
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Feb 26, 2015 07:37
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YF19pilot posted:As an engineer, I would've loved to have seen that. In simplest terms that I can, you witnessed the fluid getting caught in aerodynamic effects. Being on a control surface or lift generating device (I'd like to ask if it was actually an aileron or a flap you were observing), the air coming over is usually transitioning from laminar to turbulent flow, which can have some interesting effects. There is a thin layer of non-moving air called a boundary layer, which exists in the laminar flow regions. When it gets too big, the flow transitions from laminar (smooth) to turbulent behavior. Possibly you saw the water getting trapped in that transitional area, or the water was being atomized and the pooling was just most of the fluid coming together in a common area (which can be caused by how the air flows over the wing). It was pretty drat cool to watch, like a magic trick. I had to suppress the urge to press the call button and do my best Shatner "Some . . . Thing . . . on the Wing". Also, aileron for certain.
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Feb 26, 2015 07:55
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drunkill posted:Bit of a laugh: eh, it's been done. 
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Feb 26, 2015 14:32
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Aeronautical Insanity: Thundering typhoons, some people air travel for fun!
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Feb 26, 2015 15:04
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Slo-Tek posted:Well, this is aeronautical and insane. First pictures I've seen of the Stratolaunch mothership in construction. Will be the largest airplane ever, by a healthy margin, when it is complete. Twin-hulled, twin-boom, 6 engine White-Knight style lifter designed to carry a medium sized 3 stage rocket up to altitude and launch satellites into LEO. Am I mistaken or is that six B777 engines? 
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Feb 26, 2015 15:09
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Mortabis posted:Am I mistaken or is that six B777 engines? According to Wikipedia, no, they're 'planned to be sourced from 2 747-400s', so probably CF6s (I'd love to hear the sound of 6 RB211s mind you)
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Feb 26, 2015 15:14
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SybilVimes posted:According to Wikipedia, no, they're 'planned to be sourced from 2 747-400s', so probably CF6s (I'd love to hear the sound of 6 RB211s mind you) Comedy option: Pratt and Whitney 4056s. (gently caress Pratt and Whitney cowlings, for ever and ever.)
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Feb 26, 2015 15:30
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MrYenko posted:Comedy option: Pratt and Whitney 4056s. According to the article, they are going to use refurbished P&W 4056s. 
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Feb 26, 2015 15:51
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They're good engines, they're just a pain to work on. CF6s break a bit more, but are MUCH easier to get open. I have no comment on RB211s.
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Feb 26, 2015 16:33
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Linedance posted:So the two types of deicing fluid are different properties and viscosities, the orange one literally sticks around when all the green stuff has blown off. At a guess I'd say what you were seeing was probably the where the boundary layer of air across the top surface of the wing stops being laminar and becomes turbulent. As these rolling vortices start forming at the trailing edge they would start to lift up the viscous deicing fluid and draw it in to a little wave. The reason I'd posit for you only seeing the effect on the aileron is that the wing is probably designed that way, so that these aerodynamic effects happen deliberately over the ailerons. There are are different types of deicing fluid, yes. That's dependent on the mixture of etholyne glycol and water. What he saw was deicing fluid and anti-icing fluid. Green snotty looking poo poo is anti-icing fluid. It'll collect any falling precip, which will slough off the wing during takeoff roll.
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Feb 26, 2015 17:07
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Most de-ice/anti-ice fluid today is propylene glycol, as it is much less toxic; in fact propylene glycol is a common food additive. Also the the thickness of anti-ice fluid is generally a result of other food-grade additives, like guar gum or something similar. That said, I wouldn't go drink a glass of Type IV anytime soon; the corrosion inhibitors typically found in it are pretty bad for you.
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Feb 26, 2015 21:17
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Who can identify this airplane ? http://i.imgur.com/8nyBNBd.jpg Linked so I don't break tables.
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Feb 26, 2015 22:50
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Captain Apollo posted:Who can identify this airplane ? http://i.imgur.com/8nyBNBd.jpg Fouga CM.170 Magister
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Feb 26, 2015 22:51
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All Hail Yenko - True aircraft identifier of the gods. How the hell did you know that?
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Feb 26, 2015 23:29
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Captain Apollo posted:All Hail Yenko - True aircraft identifier of the gods. The list of butterfly tail tandem seat jet trainers is not a large one.
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Feb 26, 2015 23:49
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What are the advantages, if any, of a V-tail design?
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Feb 27, 2015 00:18
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Increased rate of doctor mortality?
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Feb 27, 2015 00:27
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Inacio posted:What are the advantages, if any, of a V-tail design? There is less interference drag from fewer structures that interact with the relative wind. It's also a bit lighter.
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Feb 27, 2015 00:33
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Inacio posted:What are the advantages, if any, of a V-tail design? For one, a V-tail is aerodynamically and structurally more efficient than a conventional set of stabilisers. There are some disadvantages, like needing very complicated control linkages (for conventional controls) and some weird coupling effects under certain conditions.
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Feb 27, 2015 00:35
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MrYenko posted:Comedy option: Pratt and Whitney 4056s. Huh. quote:Built for Stratolaunch by Scaled Composites, the Roc will be the largest aircraft ever made with a wingspan of 385 ft. This compares to 320 ft for the Hughes H-4 Hercules (Spruce Goose), 290 ft for the six-engined Antonov An-225, 262 ft. for the Airbus A380, and 225 ft. for the Boeing 747-8. Powered by six reconditioned Pratt & Whitney PW4056 engines salvaged along with other parts from two ex-United Airlines Boeing 747-400s, the twin-fuselage carrier aircraft resembles a vastly enlarged version of the Scaled-built WhiteKnightTwo developed for Virgin Galactic.
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Feb 27, 2015 01:22
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Sanguine posted:Increased rate of doctor mortality? I appreciated this post
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Feb 27, 2015 01:30
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MrChips posted:For one, a V-tail is aerodynamically and structurally more efficient than a conventional set of stabilisers. What, seriously? And control authority is not at all affected by the weirdass setup?
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Feb 27, 2015 01:30
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Sanguine posted:Increased rate of doctor mortality? Saw this joke augering in from 15,000 feet: still chuckled.
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Feb 27, 2015 02:42
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Why does all the apache chat happen when I look away for a couple days?iyaayas01 posted:I think Hughes actually did something like that for the Apache way back when it was first introduced, but it wasn't nearly as cool. I am really pissed that I can't find the pic from the Longbow release ceremony where they had a native american dude on horseback. gently caress. iyaayas01 posted:Army doesn't fly their RPAs from CONUS, they fly from in-theater. Everybody/everything rotates in/out with each new Army unit deploying/redeploying. This is basically correct. The Army doesn't have RPAs, where (in my understanding) an actual dude with aviator wings might be doing stick and rudder work, they have UAS operated by non-rated enlisted soldiers. So nobody is actually flying any of the Army ones, they're really just being operated and managed. Level 4 teaming between manned and unmanned systems doesn't require anyone to do any more flying, just opens up opportunities for a gun pilot to do sensor work way way way ahead of where they are physically located. In GWOT terms: an attack weapons team rushes to a TIC 30 minutes away. For the entire en-route portion of that flight, the sensor on the front of the aircraft is worthless WRT the TIC because it lacks line of sight. The front seater arrives on scene and is expected to throw rounds in close proximity to friendly forces that are spread all over an unfamiliar urban environment. He/she has to learn which building is which in this complicated neighborhood while being driven in circles and staring at a constantly rotating feed from a camera that's pointing 90 degrees left of how they're sitting. With teaming, they can redirect a nearby gray eagle over there and start building SA while they're still in the FARP. Front seater arrives on station already knowing where everyone is, big advantage. In tank fight terms: SAMs and ADA are scary as gently caress. I'm gonna hide below treetop level two mountain ranges away while passively watching that expendable UAS poke its head over hilltops. If I can control its laser designator, I can sling hellfires from behind cover and they'll fly to whatever it's lasing. As far as the deploying thing goes: Major systems like aircraft don't necessarily rotate in and out with every unit, they stay in the fight for as long as the engineers determined they can be ridden hard before needing a reset at a higher level maintenance facility back in the states. Every time I've deployed we've either given all of our aircraft and major support equipment to another unit before leaving, or taken our stuff down range and left it there for the next guy. MrYenko posted:How are we supposed to get badass Apache/Grey Eagle formation videos if the pilot has to fly both birds? Army declares Chinook no longer the only aircraft that can midair with itself after junior Apache pilot enters wrong grid in drone software.
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Feb 27, 2015 03:28
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Hermsgervørden posted:Cross-posting this from the physics thread in ask/tell: I made an observation yesterday, and I couldn't understand what was going on. My family and I were departing Rochester airport, where weather conditions are best explained by analogy to Hoth as far as my California mind is concerned, and our plane (Embraer 175) had to undergo a deicing procedure before we could flee the frozen Northeast. My daughter and I were seated behind the wing, and we got a great view of the anti-ice fluid streaming off the trailing edge as we took off. But I noticed something really surprising (to me) on the aileron. A pool of green anti-ice fluid persisted on the back half of the top surface of the aileron well after takeoff which as I watched changed from a mostly flat pool of fluid into a standing wave, maybe 3-6 inches tall, almost like a mohawk. It hung around for maybe a minute or two after takeoff. I could not take a picture because my daughter was already very engaged with my phone. Can anyone explain what was going on there? It definitely did not freeze. I'm not sure what exactly the fluid was, the plane was sprayed twice, first with orange fluid, then with green fluid. The green stuff was still all over the wing when we started the take-off roll. It was dancing and rippling and waving. As far as I could tell, it sort of dripped away upward, perpendicular to the top surface of the aileron. I'd point out that the fluid only acted strangely on the aileron, on the wing surface on either side, and the flaps closer to the wing root, the anti-ice fluid just streamed off as I expected, like rain off a car window. Airflow and pressure changes around airplanes does some weird stuff. That sounds like it would be really cool to watch. There's a spot on the back of the engine on an E-2 that tends to collect fluid in a similar way. It's not uncommon to look out and see oil/condensation/other crap streaming back and pooling up in a little blob right on the bottom of the exhaust can. Handy for identifying what exactly is leaking at any given time. 
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Feb 27, 2015 03:34
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MrChips posted:There are some disadvantages, like needing very complicated control linkages (for conventional controls) and some weird coupling effects under certain conditions. It is a bit odd doing a forward slip on final with full rudder and running out of elevator as you enter ground effect. That is about the only time I can tell I am flying a vtail. Inverted vtails are the best vtail's. They actually induce the correct rolling motion when used for yaw. 
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Feb 27, 2015 03:46
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I don't know if I'll ever stop looking askance at people who say "mill" for "engine."
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Feb 27, 2015 06:54
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Sanguine posted:Increased rate of doctor mortality?
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Feb 27, 2015 18:13
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Ambihelical Hexnut posted:Army declares Chinook no longer the only aircraft that can midair with itself What (wait do you mean like the rotors can smack into eachother?)
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Feb 27, 2015 22:38
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Phy posted:What Yeah, the rotors have to be synchronized to keep from hitting each other, like the valves and pistons of an interference engine. If, say, the front rotor driveshaft or one of the gearboxes gives up the ghost, one rotor can slow down while the other remains at full speed, so they end up shredding each other. Also makes it impossible to autorotate in that situation. Obviously.
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Feb 27, 2015 23:31
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Fucknag posted:Yeah, the rotors have to be synchronized to keep from hitting each other, like the valves and pistons of an interference engine. If, say, the front rotor driveshaft or one of the gearboxes gives up the ghost, one rotor can slow down while the other remains at full speed, so they end up shredding each other. Chinook ain't got nothing on the K-Max  Comedy option: 
vessbot fucked around with this message at 01:26 on Feb 28, 2015 |
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Feb 28, 2015 01:21
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vessbot posted:Chinook ain't got nothing on the K-Max That top one is the comedy option. Jesus, what the hell? "Trust me, I'm an engineer!"
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Feb 28, 2015 01:30
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More rotors! More god damned rotors all over everything!
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Feb 28, 2015 02:09
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Kellett XR-10, 1947: http://youtu.be/pl9IiVf4Vs0 Like the K-Max, bit with two 3-bladed rotors! According to Wiki, it suffered a blade collision in flight but it did not bring the helicopter down (however, another problem did.)
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Feb 28, 2015 02:15
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They got the bulge wrong, it should slope outward on the bottom to accommodate the test pilot's gigantic balls.
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Feb 28, 2015 02:16
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bitcoin bastard posted:They got the bulge wrong, it should slope outward on the bottom to accommodate the test pilot's gigantic balls. Funny you should say that, that photo is of the unmanned version.  Though it's based on a piloted design. I saw one once at Lancaster, CA airfield and was really, really confused.
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Feb 28, 2015 02:18
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Phy posted:What The CH-46 and -47 used to be 'affectionately' known as the Boeing Body Bags. The crew chiefs routinely walked out of both helos soaked in transmission fluid, and in one case, a -46 from my father's squadron back in 1990 threw a rotor blade off the coast of Virginia Beach and loving *exploded* when it impacted the other rotor housing, severing fuel lines and igniting the tanks.
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Feb 28, 2015 02:54
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BIG HEADLINE posted:The CH-46 and -47 used to be 'affectionately' known as the Boeing Body Bags. The crew chiefs routinely walked out of both helos soaked in transmission fluid, and in one case, a -46 from my father's squadron back in 1990 threw a rotor blade off the coast of Virginia Beach and loving *exploded* when it impacted the other rotor housing, severing fuel lines and igniting the tanks. Did you make the face in your avatar when he told you about that? Cause I am now. Jesus.
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Feb 28, 2015 03:15
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Phy posted:Did you make the face in your avatar when he told you about that? Cause I am now. Jesus. Actually, the reason I remember it so vividly is that we were going up to bury my grandfather's ashes in New York and we heard about it on the drive up on the radio - whenever anything Navy-related crashes in the Hampton Roads area it's like the Kennedy assassination. My father had been the squadron's maintenance officer, but wasn't when this had happened since he was well into the process of transitioning to CH-53Es for his command tour. http://articles.dailypress.com/1990-07-03/news/9007030193_1_helicopter-rotor-blades-sea-knights BIG HEADLINE fucked around with this message at 03:49 on Feb 28, 2015 |
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Feb 28, 2015 03:47
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Obviously the solution to all this rotor-caused self destruction is to just switch to twin ducted fans like those cool gunships in Avatar. Sure you lose the ability to auto rotate but you also look way cooler.
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Feb 28, 2015 03:51
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