J-20 5th Gen Fighter Thread IV (Closed to posting)

[Air Force Brat]

so kwai, you are only about 50 miles away from me, I live North of Alton, Il, back OT, do they still use air to start turbine engines, and how does all that work??? I've seen the carts with a large 6" or so flex tube???? is that air conditioning??

guys, time for some more pictures, I'll even take a CGI, I would love to see this bird in white, with orange accents, ala the old Navy paint, did I tell you I love recognition orange?? Oh, and I ticked my Dad off one time by asking him why the Navy guys had the very kool orange flight suits, while USAF had sage green????

 

[kwaigonegin]

so kwai, you are only about 50 miles away from me, I live North of Alton, Il, back OT, do they still use air to start turbine engines, and how does all that work??? I've seen the carts with a large 6" or so flex tube???? is that air conditioning??

There are specialized A/C GPUs used mainly in commercial aircrafts so passengers don't fry inside the cabin when the heavy is delayed etc
Also depends on the airport. Some have them some don't especially smaller ones.

 

[Tyloe]

These questions might already be covered in this thread but they're been puzzling me for a while now. Regarding the new prototypes, why are the fairings on each side under the leading edge extension shaped differently? like the fairing on the left edge seems to be protrudingly more distinctive than the one on the right. Also would the stingers, which are now longer and vertical, but also closer to the engine nozzles, interfere with future thrust vectoring engines? The previous two prototypes and the Pakfa seem to have larger gaps to make room and flexibility for 3D thrust vectoring engines. Or does this mean Chengdu opted to design the stingers according to future engines that vector in 2D instead of 3D? sorry if these questions are making a reappearance.

 

[Air Force Brat]

These questions might already be covered in this thread but they're been puzzling me for a while now. Regarding the new prototypes, why are the fairings on each side under the leading edge extension shaped differently? like the fairing on the left edge seems to be protrudingly more distinctive than the one on the right. Also would the stingers, which are now longer and vertical, but also closer to the engine nozzles, interfere with future thrust vectoring engines? The previous two prototypes and the Pakfa seem to have larger gaps to make room and flexibility for 3D thrust vectoring engines. Or does this mean Chengdu opted to design the stingers according to future engines that vector in 2D instead of 3D? sorry if these questions are making a reappearance.

A good question Ty, not sure about the fairings please post picture if you can, most often aircraft are very symmetrical, but there are exceptions such as underwing radar fairings on a Cessna 210 or Beechcraft A-36 BC. As to the tail stings, the Eng would say that Dr. Song never intended to install OVT on the J-20, I still maintain that he did, but Eng has convinced me that it is very unlikely to be OVT equipped, and your observation could be valid either way-----NO OVT or 2D OVT.

 

[Tyloe]

A good question Ty, not sure about the fairings please post picture if you can, most often aircraft are very symmetrical, but there are exceptions such as underwing radar fairings on a Cessna 210 or Beechcraft A-36 BC. As to the tail stings, the Eng would say that Dr. Song never intended to install OVT on the J-20, I still maintain that he did, but Eng has convinced me that it is very unlikely to be OVT equipped, and your observation could be valid either way-----NO OVT or 2D OVT.

These photos sourced from previous posts on this thread, shows the fairing under the edge extensions seem to be shaped differently. I also drew a rough sketch to show what the fairings seem to be on a diagram.

You're probably right, maybe its two different radars in the fairings or a test to see which shape is aerodynamically better. From looking at the recent prototypes, the left fairing (left from the bottom view) seems a bit longer and smoother, while the right fairing seems to be shorter and more distinctive. Also like you said, the J-20 prototypes may indicate that future engines might have 2D thrust vectoring or none like the F-35 (not STOVL). But the F-15 STOL/MTD had 3D thrust vectoring engines and showed tha nozzles can turn as much as 20 degrees in any direction even in the close confinement between the stabilisers. Although the su-35 and Pakfa's nozzles can probably turn at a greater angle because of the wider gap. Maybe Chengdu is aiming for 3D or 2D thrust vectoring but considering they also still need to produce the engine with the needed thrust to weight ratio first would mean they're under a lot of pressure to build them within the relatively short time frame before the 2017-2020 introduction into the Air force followed by mass production.

 

[gambit]

That's more likely, and with the start cart/generator you can run the whole bird sans engines, particularly all the self diagnostics, and you can bet everything has a test series and a "read-out" of the results. You can see the control surfaces "self check" on each pre-flight video we have of the J-20. On a fighter aircraft,,,,,, you would need to be very cautious working around control surfaces, doors etc, as they are very dangerous if you are in the wrong place at the wrong time.

Without engine power, the cart provides electrical and air power for most ground operations, all the way up to engine starts. If hydraulics are required to move the flight control surfaces, another ground support vehicle is available and this one provides only hydraulic pressure. If the J-20 uses dual hydraulics systems, and most likely it does, then there should be four external hydraulics receptacles somewhere on the lower/back half of the fuselage. In the USAF, we call the external hydraulics support truck -- a 'mule'. No ideas where that slang came from. Just something old and been around.

On the jet, the four external hydraulics receptacles should be approximately waist high. Believe it or not, we found out that is the best height for 90% of the people to perform a one-man hook up. These hoses must withstand 3000 psi and each hose is stiff and heavy, especially towards the connector. At waist height, a person is able to use the entire upper body strength to lift, mate, and with one hand turns the connector. If the jet is fully loaded, fuel and ord, it may sit lower enough where a two-man hook up is required. But if the jet's maintenance accessibility is well thought out, it should require just one man. I knew girls fresh out of tech school (Lowry AFB) who can hook up all four hoses on the F-111 and each by herself.

 

[Air Force Brat]

Without engine power, the cart provides electrical and air power for most ground operations, all the way up to engine starts. If hydraulics are required to move the flight control surfaces, another ground support vehicle is available and this one provides only hydraulic pressure. If the J-20 uses dual hydraulics systems, and most likely it does, then there should be four external hydraulics receptacles somewhere on the lower/back half of the fuselage. In the USAF, we call the external hydraulics support truck -- a 'mule'. No ideas where that slang came from. Just something old and been around.

On the jet, the four external hydraulics receptacles should be approximately waist high. Believe it or not, we found out that is the best height for 90% of the people to perform a one-man hook up. These hoses must withstand 3000 psi and each hose is stiff and heavy, especially towards the connector. At waist height, a person is able to use the entire upper body strength to lift, mate, and with one hand turns the connector. If the jet is fully loaded, fuel and ord, it may sit lower enough where a two-man hook up is required. But if the jet's maintenance accessibility is well thought out, it should require just one man. I knew girls fresh out of tech school (Lowry AFB) who can hook up all four hoses on the F-111 and each by herself.

outstanding post gambit, we used the mule in the shop primarily for retract tests in civilian life, on a humorous--(since we didn't blow our heads off??? note). The Illinois State Police brought their birds to Klem's for annuals and inspections, they had blown the gear down on their Cessna 414, which due to the design required a "nitrogen bottle". Another mechanic and myself were attempting to recharge the nitrogen bottle and couldn't get it over 600 foot pounds, we read and reread the Cessna service manual several times and backward and forward, no luck. This was on Saturday and the shop closed officially around noonish, and Klem had already gone home.... When I came in Monday evening to the shop, after my regular job, Klem said "well theres one of the lucky idiots right there"..... I'm like what? Klem pointed to the swollen aluminum tank on the firewall and said, somebody was watching out for you two idiots.... I said what happened to that tank, and he said you guys were try to put 1400 ft pounds in this tank, and it call for 1400 "inch" pounds, its a wonder you two didn't blow your heads off,,,,,,, he wasn't so much ticked as he was relieved. Yes, he did have to buy the state police a new nitrogen tank, but live and learn.....but it still makes me cringe....

 

[gambit]

outstanding post gambit, we used the mule in the shop primarily for retract tests in civilian life, on a humorous--(since we didn't blow our heads off??? note). The Illinois State Police brought their birds to Klem's for annuals and inspections, they had blown the gear down on their Cessna 414, which due to the design required a "nitrogen bottle". Another mechanic and myself were attempting to recharge the nitrogen bottle and couldn't get it over 600 foot pounds, we read and reread the Cessna service manual several times and backward and forward, no luck. This was on Saturday and the shop closed officially around noonish, and Klem had already gone home.... When I came in Monday evening to the shop, after my regular job, Klem said "well theres one of the lucky idiots right there"..... I'm like what? Klem pointed to the swollen aluminum tank on the firewall and said, somebody was watching out for you two idiots.... I said what happened to that tank, and he said you guys were try to put 1400 ft pounds in this tank, and it call for 1400 "inch" pounds, its a wonder you two didn't blow your heads off,,,,,,, he wasn't so much ticked as he was relieved. Yes, he did have to buy the state police a new nitrogen tank, but live and learn.....but it still makes me cringe....

Rated but over engineered and that saved you guys.

 

[Quickie]

outstanding post gambit, we used the mule in the shop primarily for retract tests in civilian life, on a humorous--(since we didn't blow our heads off??? note). The Illinois State Police brought their birds to Klem's for annuals and inspections, they had blown the gear down on their Cessna 414, which due to the design required a "nitrogen bottle". Another mechanic and myself were attempting to recharge the nitrogen bottle and couldn't get it over 600 foot pounds, we read and reread the Cessna service manual several times and backward and forward, no luck. This was on Saturday and the shop closed officially around noonish, and Klem had already gone home.... When I came in Monday evening to the shop, after my regular job, Klem said "well theres one of the lucky idiots right there"..... I'm like what? Klem pointed to the swollen aluminum tank on the firewall and said, somebody was watching out for you two idiots.... I said what happened to that tank, and he said you guys were try to put 1400 ft pounds in this tank, and it call for 1400 "inch" pounds, its a wonder you two didn't blow your heads off,,,,,,, he wasn't so much ticked as he was relieved. Yes, he did have to buy the state police a new nitrogen tank, but live and learn.....but it still makes me cringe....

1400 ft pounds as in 1400 pounds per sq ft, and 1400 "inch" pounds as in 1400 pounds per sq inch?

If so, you probably got the 2 figures reversed here.

and he said you guys were try to put 1400 ft pounds in this tank, and it call for 1400 "inch" pounds,

 

[Equation]

1400 ft pounds as in 1400 pounds per sq ft, and 1400 "inch" pounds as in 1400 pounds per sq inch?

If so, you probably got the 2 figures reversed here.

No it means 1400 pounds per inch is much greater than the 1400 pounds per feet. There's 12 inches in a foot, so therefore the comparison in feet would be: 16,800 pounds per feet > 1400 pounds per feet

See the difference?