Xlucine

Duffelblog is a national treasure

Meh...
 
Planes. Planes. Planes. Planes.
 
Wait a tick...
 
 
 
 

 
Is that a redhead? Or a faded photo.
 
Doesn't matter to me.
 
Planes and redheads.
 
Don's interested is suddenly piqued.

Every so often someone asks a question about the advantages of forward-swept wings, and usually they get a shitty half-assed answer about how they somehow improve maneuverability and stuff.  I will attempt to provide a fully-assed answer.
 
The short version is that forward swept wings do roughly the same thing as conventional aft swept wings; they increase critical mach number.  I found an excellent video explaining transonic effects, so watch that first if you don't already know what that is.
 
Typically, a straight wing starts experiencing shock wave buildup at around mach .7.  These effects are generally bad; control surfaces lose effectiveness, the aircraft's center of lift moves, stability can decrease, and drag greatly increases.
 
It's generally desirable to delay the onset of this badness.  The critical mach number is strongly affected by the thickness to chord ratio:
 
 

 
 
 
So, critical mach number could be increased by having really thin wings.  The F-104 does this, but at the expense of having ridiculously tiny wings that generate barely any lift and no internal volume for fuel storage.
 
Critical mach number could also be delayed by having wings with a normal thickness, but very long chord.  This would improve the supersonic performance of the wing, but subsonic drag would be negatively affected, because the wing would have a large amount of induced drag, and additional wetted area that would cause more drag.
 
Finally, the wing could be swept.  This would increase the chord length relative to the airflow, but would not give the wing undue surface area and thus subsonic drag.
 
In theory, the critical mach number could be increased by a factor equal to the inverse of the cosine of the sweep angle (much like calculating the LOS thickness of tank armor, and for the same reason), but secondary effects mean that it's less effective than this.  The practical effect of sweep on drag coefficient looks about like this:
 

(from Design for Air Combat)
 
This, incidentally, is why the ME-262 doesn't really have swept wings.  The change in Mcr is basically negligible for any leading edge sweep under thirty degrees.
 
Note that this logic applies whether the wings are swept forwards or backwards; as far as delaying and reducing the transonic effects, forward or rearward sweep should be equally effective.
 
There are some secondary effects that make forward-swept wings more desirable.  One of these is spanwise flow:
 

 
In any swept wing, the air isn't just flowing over the wing, it's flowing across them as well.  This means that while pulling Gs the tips of the wings will stall first.  Since the tips aren't producing lift anymore, but the rest of the wing is, the center of lift of the wing moves forward, which means that there's more pitch-up torque on the plane, which means that the nose goes up even more and the stall gets worse.  This is known as the "sabre dance," as the F-100 displayed this undesirable property.  With the wings forward swept, the root of the wings would stall first (although in practice, forward swept wing aircraft tend to have the wings attached well aft, so the CL still shifts forward during a stall)
 
To make matters worse, the air spilling out sideways and the early stall interfere with the effectiveness of the ailerons, which means that the aircraft can lose roll control effectiveness as it increases AOA.  This is a particularly alarming behavior during landing, as speed is low, AOA is high, and keeping the aircraft level is of paramount importance.
 
Additionally, the air spilling out outwards towards the wingtips reduces lift.  Reducing this bad behavior increases lift coefficient, therefore.
 
So, forward swept wings are a little more efficient, aerodynamically than aft swept wings.  Why aren't they more popular?
 
The problem is something called aeroelastic divergence; which is engineer-speak for "the goddamn wings try to tear themselves off."  I will attempt to illustrate with the finest MS pain diagrams:
 

 
The amount of lift that a wing generates is a function of the angle of attack.  The wing will generate more lift the more inclined it is relative to the airflow.
 
Wings in the real world are, of course, not perfectly rigid, so when they generate lift in order to pull the weight of the fuselage through the sky, they bend slightly.
 
In swept wings, the wings aren't just bending, they're twisting as well because the center of lift is not aligned with the structural connection between the fuselage.
 
In an aft-swept wing, the force of the lift tends to twist the wings downwards.  Increasing the angle of attack will increase the lift, which will increase this downward twist, which is a naturally self-limiting (negative feedback) arrangement.
 
In a forward-swept wing, it's exactly the opposite.  When the angle of attack increases, lift increases and the wings twist themselves upwards, which increases lift even more which increases the twisting...
 
This is why forward-swept wings had to wait until magical composites with magical properties were available.

That certainly looks like a weapon that would be carried by an anonymous henchman standing around in the background of a super villain's top secret lair. It's the sort of gun that says "I'm wearing a bright blue contractors helmet and silver coveralls but I'm not supposed to look directly at the camera while I shuffle around in front of this forklift". It's the sort of gun that is so imposing, a guy with a toupee and tuxedo armed only with a .32 caliber pistol can shoot me from the distance of most cricket pitches while I spray the Spectre sub-machine gun futilely from the hip causing sparks to fly from the sheet metal siding the hero is hiding behind. It's the sort of weapon that the aforementioned hero wouldn't even deign to pick up as he escorts the buxom love interest through the hanger vault of the top secret lair while he attempts to track down the aforementioned super villain, before an elaborate countdown sequence blows up a recognizable World Heritage Site with a stolen nuclear device.
 
Cool find though!

Fun fact: The Inquisition at its height killed people at a lower rate than the State of Texas.

You can also see very different turrets, and it looks like extra armour over the drivers position. Googling a bit I believe those are Merk 2D's, so whatever that thing is it's getting put on early marks first

It looks like Jesus has no idea what is going on. "What is this flaming space phallus doing? Why do my children make such things? Maybe I was wrong to stop the celestial giants."

You're not trying hard enough.

Your cages should be 0.9 of ball diameter to be able to stop it without making it 'pop'. Even then, you have 50% chance to stop ball from entering spectators places, which will create all sorts of havoc between football fans like fist battles for a Messi's ball(s).

One nice thing about the Yugo was that it had rear window defrosters.  These served to keep your hands warm while you pushed it.  

Whose to say they didn't order those separately? 
 
Manhattan's Dr. Doom
 
 
Also Celestial Giants with Grenades

Reading through the articles Zin posted, I found this.  
 
7. Did Kyle’s father invent the ‘sheep, sheepdogs and wolves’ speech?
 
No. The motivational dinner table chat in which Kyle’s father tells him “there are three types of people in the world: wolves, sheep and sheepdogs” has a far longer history - although not in Kyle’s memoir. As Slate point out, Hall made up the scene, but the analogy comes from Lieutenant Colonel David Grossman’s 2004 book On Combat. Grossman claims he borrowed it from an “old war veteran”, and uses the phrase in relation to the 9/11 attacks and the Iraq war. It’s since been picked up by gun rights groups, military and police circles.
 
         
 
Is it just me or does this sound suspiciously like the Dicks, Pussies and Assholes speech from team America?
 

I have not seen the film.  I suppose people like a good war film regardless of who it is about.  I will say that I am always slightly suspicious of anything published in the NY Post.  It's not exactly the finest of newspapers.  Still, interesting response.
 
Earlier today I made a facebook post regarding sniper movies.  It was:
 
So snipers have been in the news quite a bit. Guess it has to do with this new Clint Eastwood Movie. Even local steakhouses seem to have an opinion on the matter. Personally, I have not seen the film and I probably won't bother to watch it. If it had been up to me to make a movie about a sniper, it would have been about World War II Soviet sniper Lyudmila Pavlichenko. I have three reasons for this.
1) She was credited with shooting 309 Nazis. If you are going to shoot 309 people, Nazis are probably your best choice. Those guys kinda had it coming.
2) She became friends with Eleanor Roosevelt.
3) Woody Guthrie wrote a song about her.
I rest my case.

Fuck your rockets and space travel nonsense, the BUFF lives again!!!!!!
 
Ready for take off.
 

 
Cruising
 

 
Dropping ordinance
 

 
Fly-by of KSC
 

 
Climbing
 

 
Banking
 

 
Landing
 

 
Success
 

It varies I suppose. If the seal pulls the whole fish out and eats it, I wouldn't know because it's gone (other than the suspicious hole ripped in the net). But they do seem to prefer the heads because that's where all the crunchy nutrition is, Omega oils and what not. If you watch a bear on the beach eat a dead salmon, they'll crunch off the head, then eat the guts and eggs, then they'll strip off the skin and fat. Only then will they eat the meat. Whereas humans cut off the head, chuck the guts, get rid of the skin and eat the meat.

And they're not making it? but I need 200k psi guns in my life

Thinking about the effect of a heavier boolit on the combustion, it reminded me of what my thermo lecturer was talking about with the idealised otto cyle and diesel cycle - modelling the combustion as simple heat addition, a heavier boolit will get more PdV work.
 
So, the otto cycle is more efficient than a diesel cycle ceteris paribus - this is because the ignition of the fuel is so quick it's kinda like isochoric heat addition (i.e. constant volume), whereas diesels are limited by the time it takes to inject the fuel* so are better approximated by isobaric heat addition (constant pressure, so with volume increasing). Since some travel is taking place in the diesel cycle before all the heat is added, there's less area under the P-V diagram so less work is done.
 
*according to my lecturer, non-direct injection diesels are not halal
 
Something similar will happen with a heavier boolit - it will have moved less before all the propellant is combusted, so it's closer to the ideal of holding the bullet in place until all the propellant has combusted to maximise PdV work*. A light boolit, OTOH, will have moved down the tube more when the pressure in the chamber was low, so doesn't get as much work done on it. The rate of combustion is probably proportional to pressure and temp as well, giving an even more pronounced effect. All this is happening completely separate to the not-quasi-equilibrium thingy with the ratio of propellant gas speeds and boolit speed - that reduces efficiency towards the end of the barrel, whereas this reduces efficiency near the chamber where velocities are much lower
 
*maximum pressure limits are for wusses

Comrade, please

It looks like here has "show all" set as default. Of course, no way of knowing for sure until february
 
 
On TN, at the top of each board there's a bar with buttons for "recently updated", "start date", etc - different ways to filter the threads. right hand side of the row of buttons is called "custom", you can set the desired cutoff date in that

T-84-120 "Yatagan"
 

 
    "Yatagan" MBT (Object 478N, also known as T-84-120 and KERN2-120) - tank developed in 1999-2000 by Morozov design bureau. It was  modification of the T-84, adapted to NATO standards with a 120 mm smoothbore tank gun and new autoloader inside of new turret bustle. It was created to participate in the Turkish tender for new MBT.
 
 
   Yatagan was equipped with communication system made by French company Thomson, Belgian MG (FN Herstal), and other components of European manufacturers.    On different photos Yatagan can be seen with at least three different 120mm gun (different barrels are give-away) of various designs, which at various times have been tested on this tank (rumors are speaking about Swiss Ordnance Enterprise Corp. being one of producers of the gun barrels). As the winner of the 2-years long tender was Leopard 2, Yatagan was not produced and currently exists only as a prototype.  
    It had pretty powerfull 1200 HP 6TD-2 diesel engine, wich gived to it good mobility (weight was 48 tons, so ~25 hp/t). But most interesting part of that vehicle was turret bustle mounted new autoloader.
 
 
   Autoloader was created because of one-piece nature of NATO 120 mm tank ammunition. 22 shots were stored inside of turret bustle, with 14-16 rounds in hull autoloading mechanism + small non-mechanized ammorack for 2-4 shots. RoF was up to 10. Ammunition was standart NATO rounds, with addition of Ukrianian-made 120 mm GL-ATGMs. Tank also was armed with coaxial 7.62 GPMG and remotelly controlled 12.7 HMG on a commander hatch.
 
   Vehicle had thermal imagers, stabs and all other sorts of electronics you can expect from 2000-made MBT. But as i said, it didn't won tender, and never was produced. It is possible that Yatagan gave to engineers a basis for creation of the BM Oplot.
 
 
 
 
     Here is albums of this vehicle.
 
Crew compartment photos: http://imgur.com/a/SNsl2
 
Up-close pictures: http://imgur.com/a/EFcdn
 
PR iamges: http://imgur.com/a/UwQ9m

Pictures of the T-64-B1M
 

 
      I picked some photos of the T-64-B1M, which is T-64 modification for Kongo (which Kongo will never receive) because of the better looks (  ). It is largely similar to Bulat.
 

T-64BM Bulat 
 

I don't know why Ukrainian and Russian designers have such love for adding pieces of rubber on turret frontal armor.
 
     T-64BM Bulat is Ukrainian modernization of older T-64A, B and BV models. It was designed by Kharkov design bureau, tanks are modernized at Malyshev plant. Modernization price is around 1 000 000 $ for each tank. Main target for modernization is to bring T-64 to T-80U level (T-80U POWER! #Leningradpride).
 


    
     Modernization consist of adding new FCS 1A45 "Irtysh", new gunner and commander sights, new ERA (Soviet "Kontakt-5" to Ukrainian "Nozh"), some other modification to stabilizers, optics and other parts. Gunner now have day sight "Promin' " with laser rangefinder (9990 meters max, +-10 meters accuracy of range measuring), Buran-E night sight (1,5 km effective range) (Buran-Cathrine thermal imager, similar to T-90A thermal imager, also could have been mounted, but it was too expensive in eyes of Ukrainian MoD). Commander sight "Agat" is not stabilized in horizontal plane, BTW, but it allows to commander to use main gun and coaxial MG in case of emergency.     
 

Turret ERA.
 
    Turret also got new ERA layout, new, faster turret traverse mechanism. Hull is also received additional passive and active protection from th front and side (partially). 
 


 
     Tank also received better engine - 850 HP 5TDFM. After all modification tank weight reached 45 tons. 
 

 
     Overall, that tank reached T-80U level of firepower and, maybe, protection, wich is 1980s level of MBT designs. As was pointed out by Mikhail Borisuk (BM Oplot main designer) - Ukraine should stop working on T-64 modernization and start to work one more advanced vehicles like Oplot and Future MBT. 76 Bulat MBTs were already in service in Ukrainian armed forces by March of 2014. In Ukrainian civil war at least 15 were lost to this moment. Main problem of T-64 - reliability, was not really fixed. As battles showed, Nozh ERA have serious problems with chain detonation of blocks, where one hit can leave almost 30% of turret frontal projection or frotnal hull without ERA protection. Now, when temperature is dropping lower than +5 degr. C another problems of T-64 engine are starting to become visible - 5TDFM (and earlier 5TD diesels especially) is not well suited for working in cold conditions.
    During warming-up procedure engine creates toxic exhaust, which is not very good for your lungs and also creates oily condensate on air filters for maximum lulz. Number of other problems i will try to cover next time in post about perfomance of Ukrainian MBTs in civil war.

Photos of Oplot-M.
 
Albums with Oplot-M photos:
http://imgur.com/a/9XoEk
http://imgur.com/a/hYBOf
http://imgur.com/a/90Uff
http://imgur.com/a/NQ2LX
http://imgur.com/a/lK3WW
http://imgur.com/a/Klv97
http://imgur.com/a/CpeG5
 
Some others:
 
 

 
More:

BM "Oplot"
 

 

Ukrainian designers managed to make biggest panoramic sight i ever saw - overall weight of it is reaching 500 kg.
 
 
       Oplot-M, or BM "Oplot" after addoption to service in Ukrainian army, is Ukrainian MBT based on another Ukrainian MBT - T-84 "Oplot", which is Soviet-designed T-80UD with some modifications. BM Oplot was designed by Morozov Kharkiv Machine Building Design Bureau and produced by Malyshev factory. Chief designer of BM Oplot - Mikhail Dem'yanovich Borisuk (he was born in 1934, BTW).
 
 
       It have several features, separating it from T-80UD, T-90A and T-84. Engine is new 6 cylinder 6TD-2E 1200 HP diesel with lowered smokiness and exhaust toxicity (wich is a problem for Kharkov engines) in new engine-transmission compartment (which is 2 part - lower is for engine itself and upper part is for big airfilters, which are needed because of how much air 6TD "eats"), new sort-of automatical transmission. Tank is equipped with new navigation systems, FCS, panoramic sight for commander with day and night (thermal imager) capabilities, new remotely controlled KT-12.7 12.7 mm HMG for commander, new gunner sights, which bring it to modern level of how tank should be equipped. A lot of that equipment is made not in Ukraine.
 
 
From the side BM Oplot looks different from Soviet T-64-like MBTs.
 
      Main gun is not really different from 2A46 125 mm guns of T-72/ T-80/T-90 series of tanks, 125 mm KBA-3 L48 gun with autoloader for 28 shots (46 in total is carried). Main gun can fire HE, HEAT, APFSDS, GL-ATGMs (Ukrainian "Kombat" missiles). AFAIK part of ammunition is carried outside of the tank, in turret "basket", mounted to the rear part of it. Nothing really fancy here, 5 km range with ATGMs, up to 2.5-2.8 km effective range with APFSDS, which is standart for late Soviet and current Russian MBTs like T-72B3, T-80UE and different models of the T-90. 
 
     Vehicle is also equipped with Ukrainian version/local variant of Shtora system - "Varta", with additional laser-warning sensors on the turret sides. 

 
 
     BM-Oplot use somewhat unusual type of ERA (which is most interesting feature of that tank) - ~layered ERA named "Duplet". It is rumored that it can defeat tandem HEAT warheads like PG-7VR and PG-29V. Vehicle sides are also covered by Duplet ERA. 
 


      Note that the hull UFP is covered by differently shaped blocks of ERA (long and narrow). How much it is effective is unknown, but designers claim that it can defeat tandem HEAT warheads, EFP and APFSDS projectiles.  
 
Upper frontal hull armor layout:
 
Side ERA modules:
 
      Overall, BM Oplot is tank with better perfomance than T-80UD thanks to improvements in electronics and FCS, engine, transmission, driver controls, new ERA and better side armor, and in some areas this vehicle can be superioir to T-72B3 (latest Russian serial produced modification of the T-72 MBT, although it wasn't best proposed modification for it).
      But..., there is always "but" -  it is vehicle that Ukraine can not produce in any serious numbers, as their one and only contract with Thai army showed - out of 95 BM Oplot ordered in 2011 only 5-6 were delivered to this day. During trials in Thailand Kombat GL-ATGMs also showed not very good results - AFAIK out of 5 test firings, 2 missiles exploded before reaching targets. Another interesting fact about that tank is that no BM Oplot MBTs are presented on battlefields of Eastern Ukraine - T-64 and T-72s are primary tanks of the VSU. Seems to me Ukraine is either can't service them, or simply can't produce them in a first place.
 
Oplot-BM on trials in Pakistan. No accurate information on results, rumors say that Chinese VT-4 won that competition.
 
Oplot-BMs for Thai army on prooving ground.