Collimatrix

If you'd done several seconds of research you would know that this isn't true, and would have avoided looking like an idiot.  Do you have a humiliation fetish or something?

The additional height of a torsion bar isn't the diameter of the torsion bar itself.  Torsion bars almost never touch the floor of the hull.
 

 
It's almost like they need big bearings for the swing arms or something.
 
Again, you need only have taken several seconds to ascertain whether this was true or not.
 
 
For the love of Robert Hooke, that's not what "strain" means.

You categorically do not understand what you're talking about.

 

That's not the theory at all.  I'm slightly curious if you read this nonsense somewhere or came up with it on your own, but only slightly curious, so please don't belabor me with a large amount of detail.  Having more points of articulation on a suspension does not affect the force experienced by the chassis or crew.  When the tank is at rest the road wheels will exert the tank's weight against the ground via the suspension springs.  When the tank is going over an obstacle, the vertical component of the acceleration will be buffered by the travel of the independent suspension stations.  If there are more of these stations, then they will have lower K values of their springs, otherwise the suspension would just get stiffer from having more stations.  There will be a very slight difference in response from having more unsprung mass.  Having more points of articulation does increase the tendency for the tank to pitch in response to acceleration and deceleration, but for the number of roadwheels typical for tanks this distinction is immaterial.

 

Interleaved roadwheels are equivalent to overlapped ones in terms of ground pressure reduction.  Point me to any serious engineering analysis that says otherwise.

 


You need to learn that words mean things.  "Strain" has a very specific, mathematical meaning, and you are badly abusing the word here.

ERA
 

 

 
 

A patent that looks like it might be for the SU-57 air intake:

https://patents.google.com/patent/RU2460892C1/ru
 



Very interesting shock wave geometry.

You categorically do not understand what you're talking about.

 

That's not the theory at all.  I'm slightly curious if you read this nonsense somewhere or came up with it on your own, but only slightly curious, so please don't belabor me with a large amount of detail.  Having more points of articulation on a suspension does not affect the force experienced by the chassis or crew.  When the tank is at rest the road wheels will exert the tank's weight against the ground via the suspension springs.  When the tank is going over an obstacle, the vertical component of the acceleration will be buffered by the travel of the independent suspension stations.  If there are more of these stations, then they will have lower K values of their springs, otherwise the suspension would just get stiffer from having more stations.  There will be a very slight difference in response from having more unsprung mass.  Having more points of articulation does increase the tendency for the tank to pitch in response to acceleration and deceleration, but for the number of roadwheels typical for tanks this distinction is immaterial.

 

Interleaved roadwheels are equivalent to overlapped ones in terms of ground pressure reduction.  Point me to any serious engineering analysis that says otherwise.

 


You need to learn that words mean things.  "Strain" has a very specific, mathematical meaning, and you are badly abusing the word here.

A patent that looks like it might be for the SU-57 air intake:

https://patents.google.com/patent/RU2460892C1/ru
 



Very interesting shock wave geometry.

A patent that looks like it might be for the SU-57 air intake:

https://patents.google.com/patent/RU2460892C1/ru
 



Very interesting shock wave geometry.

Kamaz armored car used by PMCs in Syria and close up of 23 mm autocannon armed RCWS on moded BRDM-2s.

 
 

Some photos of K9s on the production line.
 

 

New Pecheneg-SPs in use by MoD SF in Syria.

 
 

An old mystery finally solved! The inner workings of the TKB-022 revealed courtesy of Max Popenker:
 
 

https://web.archive.org/web/20070625000343/http://www.redstone.army.mil/history/pdf/shill/shillelagh.pdf

The Breguet Range Equation looks like a distant cousin of the Tsiolkovsky Rocket Equation.

Bits of combat footage of our SF units (SSO to be specific) in Syria + loitering munition use.
 

One of the frustrations of being a child and reading lots and lots of books on combat aircraft was that there would be impressive-sounding technical terms bandied about, but no explanations.  Or if there were explanations I didn't understand them because I was a child.
 
One of the terms that got thrown around a lot was "relaxed stability" or "artificial stability" or even "instability," and this was given as one of the reasons for the F-16's superiority.  Naturally, an explanation of what on earth this was was not forthcoming, but it had something to do with making the F-16 more maneuverable.
 
This is partially true, but relaxed stability doesn't just make a plane more maneuverable.  It makes a plane better in general.
 
Why is this so?  Let's look at a schematic of a typical aircraft:
 

 
There are two points of interest here; the center of lift (CL) and center of gravity (CG).  The CL is the net point through which all aerodynamic forces acting on the aircraft pass.  Various things can cause the CL to shift around in flight, such as the wing stalling or the transition to supersonic flight, but we'll ignore that for now.
 
The CG is the net center of mass of the aircraft.  The downward force of the weight of the aircraft will act through this point, and the aircraft will rotate around this point.
 
The reason that this configuration is stable is that the amount of lift a wing generates is a function of its angle of attack (AOA, or alpha).  AOA is the angle of the moving air relative to the wing.  If the wing is more inclined relative to the air, it generates more lift up until it starts to stall.  The relationship looks like this:
 

Obviously this depends on the exact shape of the wing and the airspeed, but you get the idea.  The lift increases as alpha goes up, but falls off after the wing stalls.
 
This means that in a conventionally stable aircraft in level flight, anything that causes the nose to pitch up will cause the amount of lift to increase, but because the CL is behind the CG, this increased lift will cause a torque on the aircraft that will rotate the nose back down again.  Thus, any disturbances in pitch are self-correcting.  This is important because it means that a human being can fly the aircraft.  If random disturbances were substantially self-magnifying, the plane would begin to tumble through the air.
 
There's a bit of a problem though.  Because the CL is behind the CG, the plane has a tendency to rotate downwards.  So, to keep the plane level the tail has to apply a torque to trim out this tendency to rotate.  The torque that the tail is applying is pushing downward, which means that it's cancelling out part of the lift!  Keeping the tail deflected also increases drag.
 
These problems would go away if the arrangement were reversed, with the CG behind the CL:
 

 
However, this would make the plane unflyable for a human.  But this is the 21st century; we have better than humans.  We have computers.
 
A computer (actually, an at-least-triply-redundant set of computers) and an accelerometer detect and cancel out any divergences in pitch faster and more tirelessly than a human ever could.  The tail downforce becomes tail upforce.  Also (contrary to wikipedia's shitty diagrams), the distance between the CG and CL is closer on unstable designs, so the trim drag of the tail is smaller too.
 
OK, so unstable designs get a slight reduction in drag and a slight increase in lift.  Why is that a big deal?
 
Think of a plane as a set of compromises flying in close formation.  Everything in aerodynamics comes at a cost.  Let's take a look at how this principle can kneecap people trying to be clever.
 
The quicker of you will have no doubt objected to my characterization of stable aircraft losing lift due to tailplane downforce.  "But that doesn't apply if the plane is a canard design!  The CG will be in front of the CL, but still behind the canards, so the canards will generate an upforce to trim the plane out!  No need for fancy computer-flown planes here!"
 
Yeah, they tried that.  But the need for CG/CL relationships ends up screwing you anyhow.  Let's look at a stable canard design (and one of my favorite aircraft), the J7W1 Shinden:


 
Note that the wings are swept.  Now, this is a prop-driven plane, so I can guaran-fucking-tee you that the wings aren't swept to increase critical mach number (I don't think the designers even knew about critical mach number at the time).  Instead, the wings are swept for two reasons:
 
1)  To move the CL back so that the plane is stable
 
2)  to move the rudders back so that they're far enough behind the CG that they'll have adequate control authority.
 
There are lots of reasons you don't want swept wings on a prop fighter.  Since the thing is never going to go fast enough to encounter the benefits of them, in fact, the swept wings are almost entirely a negative.  They reduce flap effectiveness and have goony stall characteristics.  If you could get away with not having them, you would.
 
But you can't.  You can't because it's 1945 and the computers are huge and unreliable.  Your clever dual-lifting-surface canard design's advantages are heavily watered down by the disadvantages imposed by the need for stability.
 
That is the big advantage of instability.  The designer has a lot more freedom because there's one less thing they have to worry about.  This can indirectly lead to huge improvements.  Compare a mirage 3 and a mirage 2000.  The mirage 2000 is unstable, which adds some extra lift (nice, especially on takeoff where deltas really hurt for lift), but more than that it allows the designer to move the wings further forward on the fuselage, which allows for better aft-body streamlining and better area ruling.  Instability doesn't allow for better area ruling per se, but it frees the designer enough that the could potentially opt for that.

http://foxtrotalpha.jalopnik.com/how-to-win-in-a-dogfight-stories-from-a-pilot-who-flew-1682723379
 
Very interesting article.  Some takeaways:
 
 
-The East German model fulcrum wasn't particularly impressive BVR.
 
-The IRST was surprisingly lame.
 
-Mirage 2000 apparently sucked in DACT.

John W. Golan just released a video supplement to his book on the Lavi:
 

 
The video is well worth the 18:44 if you're interested in the Lavi at all.
 
 
I just got the book, but it's at the bottom of a pile of other books.

If you're interested in the Lavi, get this book.
 
About a third of the book is the story of the Lavi.  This is the story of the Israelis suddenly losing access to French and British weapons, turning to the USA as weapons suppliers, and deciding the USA wasn't quite reliable or timely enough after nearly losing the 1973 Yom Kippur War.  Thoroughly spooked, the Israelis decided to increase their self-sufficiency in weapons production, and proceeded to develop a rifle, a tank, some missile boats, and various other gadgets.  The thing about fighter planes is that they're outrageously expensive, even compared to tanks, and in the 1980s a host of must-have new technologies like fly-by-wire, directionally aligned and mono-crystal turbine engine blades, and graphite composite construction came about and made fighter aircraft even more expensive.  And some people in the US weren't too happy about the Israelis developing a jet.  As it turned out, some people in Israel weren't all that hot on the idea either. 
 
The remaining two thirds of the book are extensive appendices explaining technical, quantitative assessment of combat aircraft.  Things like the pros and cons of canard designs, E-M diagrams, operational range estimation, how pulse-doppler radar works, how range-gate-pulloff jamming works, are all covered in great detail.  In fact, anyone who is interested in the engineering aspects of the design of combat aircraft should probably get this book, because it's way cheaper than something like Design for Air Combat.

On Rheinmetall's 120 mm L55A1 and 130 mm smoothbore guns via EDR Magazine https://www.edrmagazine.eu/what-future-for-tank-guns-the-rheinmetall-view:
 
 
 
 
 
 
I guess the old DM63 Plus APFSDS was turned into the DM73 (8% improvement, using old penetrator + more powerful propellant charge) and the old DM73 was turned into the KE2020Neo aka DM73Neo (20% improvement in penetration thanks to a new penetrator and more powerful propellant charge).

A comparison of sleeve valve and poppet valve engines.
 
 
Very in-depth.

Professional Development Short Course on Tactical Missile Design
Tactical Missile Design (basically an expanded version of the above)