Chinese Trainer Aircraft (JL-8, JL-9, JL-10 (L-15), etc.)


by78

Lieutenant General
A nice overview and size comparison of the various trainers in service.

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OppositeDay

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This is old news but nobody has posted it so here it goes. AVIC is developing AG100, a 3 seats trainer, from the larger Cirrus SR22. It's powered by a ROTAX 915is and uses Garmin avionics, so pretty much not for military use. It's expected to receive civil certification by the end of this year (2022).

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I've seen suggestions for PLAAF to off-load their screening program to civilian flight schools so they don't have to maintain a large fleet of CJ-6s once they get their next gen primary trainer. However I doubt PLAAF is going that route since they care deeply about their tradition and culture. Shilao's podcast recently discussed this emphasis on rituals in the context of some PLAAF flight academies sending Y-20 to pick up incoming cadets (very expensive compared to commercial flights). Farming out screening/initial training to some outside entities (even if they're state-owned contractors) would be out of character for PLAAF, IMO. Still, AG100 is AFAIK the only Chinese trainer with side-by-side configuration, and an important development.

About the next gen primary trainer, here's a 2019 column from Shilao

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According to Shilao, in 2016 there was a formal project-funding discussion (立项论证) between CMC/PLAAF headquarters, flight academies and the defense industry (both aircraft makers and engine makers) on the next generation primary trainer project and the three phases two trainers (三级两机) training system.

The three phases two trainers system was to replace the old three phases three trainers system. In the old system an intermediate trainer (JL-8) was needed because JJ-7's low speed performance was too poor and CJ-6's maximal speed was too low so there was a huge gap between CJ-6 and JJ-7. But JL-10 has much better low speed performance than JJ-7, so half of the problem was already solved. What they needed was a CJ-6 replacement with higher maximal speed, etc. Shilao suggests both CJ-7 and TA-20 (DART-450) fall short on the maximal speed requirement. Shilao hinted that the new primary trainer would be turboprop. The article was written in 2019. Now the 1,000kW class turboprop AEP100 has already begun civil certification progress. So engine problem is about to be solved.

According to Hongdu's two most recent annual reports, they're developing a new primary trainer ("K8基础教练机曾经占有全球70%市场份额,目前正在开展新基教研制,以抢占筛选和基础教练机市场"). So Hongdu's New Primary Trainer (新基教) will cover both initial screening (筛选) and primary(基础) phases. However, the word "抢占" (seizing by superior speed) suggests there might be competitions from other companies (Guiyang?).

Hongdu's ambition in using a single aircraft to cover everything from initial screening to primary training is notable. A three phases two trainers system could take two forms: 1) a different trainer is used for each phase, however it's a "two trainers" system because the screening/initial training phase is outsourced to civilian contractors so the military flight academies only maintain two trainers 2) all phases are done in-house, and a single trainer type is used both for screening/initial training and primary training. USAF is an example of the first kind of three phases two trainers system. They use/used Cessna 172->Slingsby Firefly->Diamond DA20 for screening/initial training and T-6A for primary training. As I mentioned earlier in the context of AG100, I doubt PLAAF wants to outsource screening to outside contractors. In any case, because Hongdu claims its New Primary Trainer is capable of doing screening, it's going to be a propeller aircraft. Initial screening are not done on jet trainers for good reasons!

We know that some senior people at Hongdu were against a combined turboprop screening/initial/primary trainer type for China. Here's a 2010 paper, co-authored by K-8's chief designer, arguing in favor of a modernized piston initial trainer + modernized jet primary trainer combination for three reasons:
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1) With a tractor turboprop primary trainer, propwash on control surfaces would result in pilots forming habits that they need to correct once they switch to jet trainers, resulting in wasted training hours.
2) High performance turboprop trainers are too difficult for pilot candidates with zero prior flight hour, even candidates with good potential might fail the screening.
3) Some countries in the world have too many relatively new jet trainers!

I'm not an expert on flight control/aerodynamics, but what's people's take on Reason 1? Can modern flight control computers make propwash's effects imperceptible to the pilot? What about Reason 2? Pilatus claims PC-21 can do both initial and primary training, but how many air forces actually train their zero flight hour pilot candidates on high performance turboprop trainers? Finally what do people think of pusher turboprop trainer (e.g. a modernized twin seat Saab J-21)? There's an unofficial twin boom Advanced Pusher Trainer proposal from two Xi'an/CFTE engineers that I like:
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stannislas

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The three phases two trainers system was to replace the old three phases three trainers system. In the old system an intermediate trainer (JL-8) was needed because JJ-7's low speed performance was too poor and CJ-6's maximal speed was too low so there was a huge gap between CJ-6 and JJ-7. But JL-10 has much better low speed performance than JJ-7, so half of the problem was already solved. What they needed was a CJ-6 replacement with higher maximal speed, etc. Shilao suggests both CJ-7 and TA-20 (DART-450) fall short on the maximal speed requirement. Shilao hinted that the new primary trainer would be turboprop. The article was written in 2019. Now the 1,000kW class turboprop AEP100 has already begun civil certification progress. So engine problem is about to be solved.
now nearly 4 years later, PLAAF is still using CJ-6, but they are trying really hard to get rid of JL-8, and let the student directly jump into JL-10 after CJ-6...

in this case, CJ-6 or the primary trainer's performance is not that important anymore, it just let the student pilot to taste of flight, and conduct most of the traning on JL-10 then later J-10S or J-11BS

therefore the takeoff cost became the primer consideration and CJ-6 has a huge advantage on that, in compare with anything else
 

OppositeDay

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now nearly 4 years later, PLAAF is still using CJ-6, but they are trying really hard to get rid of JL-8, and let the student directly jump into JL-10 after CJ-6...

in this case, CJ-6 or the primary trainer's performance is not that important anymore, it just let the student pilot to taste of flight, and conduct most of the traning on JL-10 then later J-10S or J-11BS

therefore the takeoff cost became the primer consideration and CJ-6 has a huge advantage on that, in compare with anything else

The new system seems to be one year of initial+primary training on CJ-6, one year of advanced training on JL-10 and one year of conversion training. One year on CJ-6 is a long time and ideally you want to fly a lot of hours at initial/primary phase because the cost's low. CJ-6's performance, range and comfort all have room for improvement. I think the reason we're not seeing a new primary trainer right now is probably engine. They're either waiting for AEP80/100 or AEP60E (modernized WJ-9 with higher output and FADEC).
 
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stannislas

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The new system seems to be one year of initial+primary training on CJ-6, one year of advanced training on JL-10 and one year of conversion training. One year on CJ-6 is a long time and ideally you want to fly a lot of hours at initial/primary phase because the cost's low. CJ-6's performance, range and comfort all have room for improvement. I think the reason we're not seeing a new primary trainer right now is probably engine. They're either waiting for AEP80/100 or AEP60E (modernized WJ-9 with higher output and FADEC).
i doublt CJ-6 will take a year, probably only 6 months, pilot training normally start from year 3, it will take about 6 months for all the studies on the ground, the the second half the year to fly CJ-6
student in year 4 will fly JL-10 till graduation
post graduation of Air Force Aviation University, JL-10 and J-10S/J-11BS are trained at each acedemy in Xi'an/Shijiazhuang/Harbin

so most training hour should be on JL-10
 

OppositeDay

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i doublt CJ-6 will take a year, probably only 6 months, pilot training normally start from year 3, it will take about 6 months for all the studies on the ground, the the second half the year to fly CJ-6
student in year 4 will fly JL-10 till graduation
post graduation of Air Force Aviation University, JL-10 and J-10S/J-11BS are trained at each acedemy in Xi'an/Shijiazhuang/Harbin

so most training hour should be on JL-10

I rewatched the two CCTV reports on the new fighter pilot training program at Shijiazhuang. According to the 2022 report, the first group of pilots graduated from the program in July 2022. Conversion training on J-10 started in July 2021 after they finished their JL-10 training earlier in the same month. According to a 2020 report, the first group of cadets that went directly from CJ-6 to JL-10 had their first flights with JL-10 in early October 2020 after two months of ground preparations. So if they only start flying CJ-6 in spring semester 2020, they would have spent about half a year on CJ-6, a year on JL-10 and a year on J-10 when they graduated.

According to the 2010 paper I quoted earlier, in the old system initial screening/training takes 20-60 flight hours, primary training 80-140 flight hours and advanced training 80-120 flight hours. In the new system, they probably just move all primary training from JL-8 to JL-10, as they couldn't move much primary training from JL-8 to CJ-6. The performance gap between the two are too large. So a better performing initial/primary trainer is still useful under the new system so some old JL-8 lessons can be done in the first six months on the new initial/primary trainer. Also the new training system is for fighter pilots only, bomber/transport pilots are not moving directly from CJ-6 to JL-10. A turboprop replacement for CJ-6/K-8 would benefit their training as well. PC-21 level performance is probably overkill, something around PC-9 performance-wise should be sufficient.
 
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stannislas

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According to the 2010 paper I quoted earlier, in the old system initial screening/training takes 20-60 flight hours, primary training 80-140 flight hours and advanced training 80-120 flight hours. In the new system, they probably just move all primary training from JL-8 to JL-10, as they couldn't move much primary training from JL-8 to CJ-6. The performance gap between the two are too large. So a better performing initial/primary trainer is still useful under the new system so some old JL-8 lessons can be done in the first six months on the new initial/primary trainer. Also the new training system is for fighter pilots only, bomber/transport pilots are not moving directly from CJ-6 to JL-10. A turboprop replacement for CJ-6/K-8 would benefit their training as well. PC-21 level performance is probably overkill, something around PC-9 performance-wise should be sufficient.
not really, in fact the training hour of almost all the primary training programs in the airforce among the world are reduced greatly and more and more training hour are shifted to advance trainer, in this case JL-10.

in fact, there was previous report footage of some interview about the PLAAF new training program mentioned that, CJ-6 in the new system is not even intend to teach student 'how to flight' completely, but more for them to have 'some feels about flying' and for the instructor to identify the talent.
instead, most of the 'proper' training will be done in JL-10.

in the old system, there was about 100 hr in CJ-6, but in the new system, this number drops to ~45-60 hr max,

the JL-10 therefore replaced, JL-8, JJ-7, and even some part of the J-10s/j-11bs, including some weaponary training. J-10s/j-11bs were more for conversion
 
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OppositeDay

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not really, in fact the training hour of almost all the primary training programs in the airforce among the world are reduced greatly and more and more training hour are shifted to advance trainer, in this case JL-10.

in fact, there was previous report footage of some interview about the PLAAF new training program mentioned that, CJ-6 in the new system is not even intend to teach student 'how to flight' completely, but more for them to have 'some feels about flying' and for the instructor to identify the talent.
instead, most of the 'proper' training will be done in JL-10.

in the old system, there was about 100 hr in CJ-6, but in the new system, this number drops to ~45-60 hr max,

the JL-10 therefore replaced, JL-8, JJ-7, and even some part of the J-10s/j-11bs, including some weaponary training. J-10s/j-11bs were more for conversion


45-60 hours is a still a lot of time to spend on CJ-6. It's actually longer on the lower end than the number from the 2010 article I quoted (20-60 hours for screening/initial training).

Just because CJ-6 plays a certain role in the new system doesn't mean that if a better initial/primary trainer is available they will not adjust the system to make use of the new capabilities. According to the 2020 CCTV report on CJ-6 to JL-10 transition at Shijiazhuang, they spent two months on the ground preparing before flying JL-10 for the first time. The gap between CJ-6 (<300km/h cruise speed and around 6.5 m/s rate of climb) and JL-10 is huge. PLANAF once took cadets still flying CJ-6 to fly Su-30 because too many of their Su-30 pilots were being reassigned to J-15, so even bigger gaps can be bridged, but it's not ideal. A better performing replacement for CJ-6 would allow more accurate assessment of cadets' potential as fighter pilots and enable those selected for the fighter pilot program to take more advanced lessons while still flying their first trainer so to ease the transition.

Anyway, Hongdu is developing a new initial/primary trainer. The new trainer project was first announced in their annual report around the same time as the new fighter pilot training program started at Shijiazhuang (2020). I expect the use of CJ-6 in the new training program to be only temporary, and it's to be replaced by a new trainer once it's available. Let's wait and see.
 

stannislas

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45-60 hours is a still a lot of time to spend on CJ-6. It's actually longer on the lower end than the number from the 2010 article I quoted (20-60 hours for screening/initial training).
Not if you compare with international standards, say for usn or planaf these days, they are recruiting student pilots who already have some base licenses, in this case most of these pilot are still not directly jump into the cockpit of advance trainer but still fly some primer trainer until they have passed all the tests, this will take them at least 10-20 hours

so of course, the time on paper will look better in this way, but the total flight hour on each individual in primer trainers are still remain at least about 40 hour min


Just because CJ-6 plays a certain role in the new system doesn't mean that if a better initial/primary trainer is available they will not adjust the system to make use of the new capabilities. According to the 2020 CCTV report on CJ-6 to JL-10 transition at Shijiazhuang, they spent two months on the ground preparing before flying JL-10 for the first time. The gap between CJ-6 (<300km/h cruise speed and around 6.5 m/s rate of climb) and JL-10 is huge. PLANAF once took cadets still flying CJ-6 to fly Su-30 because too many of their Su-30 pilots were being reassigned to J-15, so even bigger gaps can be bridged, but it's not ideal. A better performing replacement for CJ-6 would allow more accurate assessment of cadets' potential as fighter pilots and enable those selected for the fighter pilot program to take more advanced lessons while still flying their first trainer so to ease the transition.

Anyway, Hongdu is developing a new initial/primary trainer. The new trainer project was first announced in their annual report around the same time as the new fighter pilot training program started at Shijiazhuang (2020). I expect the use of CJ-6 in the new training program to be only temporary, and it's to be replaced by a new trainer once it's available. Let's wait and see
Of course better primary trainer is going to accelerate the entire process, and let the student pilots to have a smoother transition period

but this is not all plaaf thinks, one thing you may not realize is how cheap training on CJ-6 can be, i remember I read somewhere when CJ-6 production restarted several years ago, it said the flight hour cost for CJ-6 is less than 1000 cny, which is ridiculously as most the cost are fuels. And the build cost for CJ-6 is even more ridiculous, the new CJ-6 for civilian market has all the fancy features like glass cockpit, gps and etc, but plaaf said we don’t want any of these, just the authentic CJ-6 in bare minimum, so the price dropped to just over 100k cny… which is less than 1/10 of a da-20, and given there are so many places plaaf can spend their money, I don’t think they mind to save some cents on primer trainers

this was exactly what happened to Cj-7 back then, so I think in plaaf’s mindset, CJ-6 of course is not ideal, but reach the very minimum, and it’s franking cheap, that means until they got enough JL-10 and J-10s/j-11BS, they probably won’t take primary trainer renovations/upgrades as priority something
 
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