M48A5K

K2 fording river April 19 2016
 

 

 

 

 

 
 

 
 
 

K2 fording river April 19 2016
 

 

 

 

 

 
 

 
 
 

K2 fording river April 19 2016
 

 

 

 

 

 
 

 
 
 

K2 fording river April 19 2016
 

 

 

 

 

 
 

 
 
 

K2 fording river April 19 2016
 

 

 

 

 

 
 

 
 
 

I got my copy of US Military Tracked Vehicles by Fred Crimson in the mail today.  It's a pretty nice reference book.  I feel better about paying 28 dollars for it now that the cheapest used copy available on Amazon is $85.  I'm pretty sure a PDF version is out there for those that want to hunt it down.  
 

*cracks fingers*

Something that has interested me for a while, are shape stabilised projectiles. As in, projectiles that are stable due to their shape. Everybody has heard of rotation stabilised and fin stabilised projectiles, but shape stabilised is kind of different. I guess most of you here have seen shape stabilised projectiles without actually knowing how and why they work.

Geek sidenote: Fin stabilised projectiles are actually fin and rotation stabilised.

As I said, shape stabilised projectile have a stable flight path due to their unique shape.

Figure 1: A 84mm Carl Gustav shape stabilised HEAT-round

Note the slightly ogive front and the stand-off, which are characteristic of shape stabilised projectiles (SSP). Both features are absolutely crucial for the SSP to work.
I'm going to throw you guys into the deep end by showing a .gif of the airflow in front of an SSP.
Here's a link because I can't embed .gifv apparently
The first thing you should notice is the air circulating in some-sort of pocket, and that this airflow is subsonic. Before I continue, here's the airflow in front of a blunt projectile: Clicketyclick
While that projectile has a subsonic airflow in front of it as well, it is not circulating.

Here's the airspeed of both projectiles as a normal picture:

Figure 2: Airspeed in front of an SSP


Figure 3: Airspeed in front of a blunt projectile

It's clear that an SSP has a ogive-shaped subsonic airpocket in front of the projectile. This basically emulates the ogive of a normal rotation stabilised projectile. In other words, it makes it more aerodynamic. But does that airpocket stabilise the projectile?
No it does not.

So why is this projectile stabilised? The key is in what happens when it starts to tumble. Right now, there is nothing stopping the projectile from tumbling, and that's the interesting thing. There is literally nothing stopping the projectile from tumbling, except...


the projectile itself.

Lets take a look at what happens when an SSP starts to tumble. (If I remember correctly, I rotated the projectile 10 degrees)
First off, the airflow in front of the projectile. It's fairly obvious that the airflow has changed. Lets check that again, but this time as a picture.

Figure 4: Airflow in front of a tumbling SSP

Again, it's obvious that the airflow has changed. The subsonic pocket has mainly shifted to one side and the air itself isn't really circulating in the pocket. This change causes a huge change in the Cd of the projectile. Let me show you why.

Figure 5: Pressure in front of a tumbling SSP

Next, the pressure in front of an SSP flying straight.

Figure 6: Pressure in front of an SSP flying straight

Please note the approximate pressure in front of both projectiles. The tumbling projectile has, on one side, twice the pressure as the projectile that's flying straight. Very interesting. What's even more interesting is that the pressure occurs on the opposite of the side it's turning to! The projectile is turning upwards, but the pressure builds up at the bottom. This pressure forces the projectile to start turning down again, forcing the projectile in a state where the pressure on all sides is equal.

Voila, a shape stabilised projectile.


But... why does it work?

The subsonic airpocket is created by the stand-off and that little flange, or whatever you want to call it. The dimensions and placement of both are equally important. The stand-off and its side create the airpocket and the flange give the airpocket the required shape. The stand-off size can vary, but the flange size and placement is very important. If the flange is too far forward or too far back, the airpocket will be either too small or too big. Why does the size of the pocket matter? Because of this:

Figure 7: Subsonic pocket in front of an SSP

I changed the parameters slightly and made all airflow above Mach 1 red. Whatever is not red, is trans- or subsonic. The interesting thing to note here, is the pocket extends to the edge of the projectile (if I made the projectile better it should be exactly on the edge). (Sidenote: Here's the same picture of an SSP at a 10° angle)
While the airpocket does not start at the flange, the flange determines where the pocket starts. If, at this velocity, the flange was further back, there would be supersonic flow hitting the front of the projectile, massively increasing drag. If the flange was further forward, the airpocket would be further forward too. This would mean the airpocket would not end at the edge of the projectile, but further out. Creating an airpocket which is wider than the projectile. This would allow the projectile to tumble a bit, because pressures wouldn't change much unless there is supersonic flow hitting the projectile.

It is also possible to change the size of the airpocket by changing the front of the projectile itself. If the radius connecting the front and the stand-off is too big, the airflow inside the pocket would disrupt the circulation. The same would happen if the radius is too small. The angle of the front is important as well, but I haven't expermented that much with it so I don't know how important it exactly is, but it has an effect on the airflow.

By the way, if the flange did not exist at all, the airpocket would start at around a third to half of the stand-off. Which would completely ruin the airpocket. Without a flange, the stand-off itself would have to be way bigger and longer to create the same kind of airpocket.

But Bronezhilet, I hear you cry, if the airspeed changes, the pocket changes as well!

I'm glad you brought that up, because you are right.

A shape stabilised projectile only works properly within a certain flight envelope. If the projectile is moving too fast, the airpocket would compress allowing supersonic flow to hit the front of the projectile. Which in turns increases drag. By a lot. If the projectile is moving too slow the airpocket widens, allowing the projectile to tumble a bit before it would stabilise.

I've been brainstorming with Colli a bit, and we've come to the conclusion that is why some projectiles are both shape stabilised and fin stabilised. When the projectile is moving too slow for shape stabilisation, the fins would keep it pointing in the right direction.



And that concludes today's lesson. Thank you for reading.

That pic was taken by me... I received the updated version of Poongsan brochure at ADEX 2015, and noticed that K279 and K280 were also on the list. I guess someone(maybe GRU in otvaga2004) also uploaded that on foreign forums

Sumeragi is the one that put M18 in Wargame RD. He(NOT she) was kicked from several Korean internet communities including the WOT forum last year, but seems he's still spreading false and biased information on other forums...

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

I've never liked Sumeragi. I watched the incident, and it surely did worth a popcorn.
 
   
Hellcats are...well...useful when used as a bait for ATGMs 

Sumeragi is the one that put M18 in Wargame RD. He(NOT she) was kicked from several Korean internet communities including the WOT forum last year, but seems he's still spreading false and biased information on other forums...

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

Sumeragi is the one that put M18 in Wargame RD. He(NOT she) was kicked from several Korean internet communities including the WOT forum last year, but seems he's still spreading false and biased information on other forums...

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

Sumeragi is the one that put M18 in Wargame RD. He(NOT she) was kicked from several Korean internet communities including the WOT forum last year, but seems he's still spreading false and biased information on other forums...

Ok, I have to make a small correction.  The engine that was intended for the ROKIT was the AVCR-1790, not the AVDS-1790-9A.  These two engines are easy to confuse since they are both 1200HP and are essentially the same with the exception that the AVCR-1790 had variable compression pistons while the AVDS-1790 had conventional pistons.  The AVCR 1790 was the earlier engine, it was an attempt by Teledyne Continental to use the variable ratio piston tech they had developed for the AVCR-1100 and AVCR-1360 engines for the MBT-70 and General Motors XM-1 prototypes.  Anyhow, the Teledyne engineers messed up the design and the AVCR-1790 had issues.  Not long after the AVCR-1790 suffered it's fate, Teledyne was able to get 1200HP out of a conventional piston AVDS-1790 engine by introducing improved turbo-charging and after-cooling.  The AVDS-1790-9 1200HP engine is currently in service in the Merkava III and also in the Namer APC (the engine is still in production for this vehicle.)  

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor

It's a very very long story so just a quick summary for now...got no time these days unfortunately
 
1. Daigensui(or Sumeragi; 스메라기) first appeared on Korean WOT forum 2 years ago. He introduced himself as a Korean-Japanese woman currently living in Canada and working as a consultator for WOT Japanese tank tree. Then he quickly succeeded in forming a group of fanboys, but not everyone liked him as his fanboys were somehow ruining the forum, and himself was problematic.
 
2. On June 7th 2014 some WOT players casted doubt on Sumeragi's gender. #Link1 #Link2
 
3. Then one of the forum members uploaded a series of evidences indicating that Daigensui is not a female, but actually an ex-marine named Kang Seung Jae(this part needs verification as some sources says that he was never a conscript). Other evidences also claim that Sumeragi is a male and banned from numerous forums for his lies,
 

 
4. That night the forum administrator(롤랑) invited Sumeragi to a private chat. Admin gave Sumeragi a time to defend himself, but the admin couldn't hear any repliy.
 
5. During the same period Korean Wargame RD players were complaining about M18 hellcat, which was never used by the ROK army. Then someone found out that it was Sumeragi's fault, and annoyed WRD players joined bashing him.
 
6. Sumeragi sent his explanations to the admin. #Link1 #Link2 Majority of the Korean WOT and WRD players concluded that Sumeragi's explanations aren't credible enough.
 
7. Admin made a phone call with Sumeragi. Phone number was from Vancouver, but "her" voice was definitely male's.
 
 
So now he's kicked from Korean WOT and WRD forums, but that retard currently using a sockpuppet account according to the admin.
 
 
p.s. He's also famous for pseudologia in other Korean gaming forums. According to Daigensui, he's...
 
* a twenty-something female residing in Vancouver
* a lesbian but engaged with "her" cousin
* a smartass that graduated both Tokyo and Yonsei university
* working in a major company owned by "her" relatives
* so wealthy that he can invest $10million rightaway
* a distant relative of current Japanese emperor