KJ-600: Chinese carrier-capable AEW: developments, news, progress ...


Orthan

Junior Member
Its perhaps worth noting that the Soviet Yak-44 AEWC was designed to also operate from STOBAR carriers. That primarily explains its very impressive power figures. Not saying the same will be true for the Chinese aircraft necessarily, but just pointing out fixed wing AEWC does not automatically mean it needs a CATOBAR.
Yak-44 was to use propfan engines. Compared to turboprops, they have better speed and performance, with the same fuel economy.
This is the wikipedia article:

Please, Log in or Register to view URLs content!


I dont think that china has this kind of technology. So, i assume that KJ-600 needs a catapult.
 
Last edited:

sheogorath

New Member
Registered Member
The Yak-44 was meant to use catapults though. The Ulyanovsk was equipped with a pair of them on the angled runway. I really doubt it would have been able to take off from the ramp.
 

halflife3

Junior Member
Registered Member
Yak-44 was to use propfan engines. Compared to turboprops, they have better speed and performance, with the same fuel economy.
This is the wikipedia article:

Please, Log in or Register to view URLs content!


I dont think that china has this kind of technology. So, i assume that KJ-600 needs a catapult.
Do you think it is a mistake that KJ-600 not use propfans instead of turboprops? Are propfans superior to turboprops overall?
 

sheogorath

New Member
Registered Member
Do you think it is a mistake that KJ-600 not use propfans instead of turboprops? Are propfans superior to turboprops overall?
Propfans are more like turbofans where the large fan at the front is unducted; basically a Turbofan with turboprop-like efficiency and performance. Like everything in life, though, it is a trade-off and usually the complexity of the propfan is not worth it for most aplications and you are better off with just picking a turboprop or just a normal turbofan.
 

Richard Santos

Junior Member
Registered Member
Prop fan works efficiently at higher speed range than does turbo props. It is not a better or worse technology than turbo prop Overall. Whether KJ-600 ought to have prop fans or were turbo prop the right choices depends on whether the Chinese think it is important for the KJ-600 to operate efficiently at higher speeds than where The turboprop is the most efficient.

I tend to think the Chinese made the right choice. carrier AWAC primarily needs to loiter for long periods. Loiter time is much more important than cruising speed or dash speed. Secondarily they may need the highest possible thrust at take off speeds, not at Optimal prop fan speeds.

The soviets do seem to over endow their aircraft with engine power and speed by western ideal of optimality. Post cold war accounts by soviet insiders suggest this is not always the result of different operational requirement By the Soviet military. Rather it was the result of the internal politics of the different Competing bureaus and ministries inside soviet Union military industrial complex as they jockeyed by influence and resources.
 
Last edited:

gelgoog

Senior Member
Registered Member
O/T but well, the Russians have different requirements. Their aircraft need to have enough range to cover vast distances and enough speed to intercept targets on time at those vast distances so they can cover their vast territory with less aircraft. Russia has always had lots of oil reserves so instead of spending years to eke out more fuel efficiency from the engines they simply enlarge the internal fuel tanks thus spending way less R&D resources too.

To be honest I think propfans and turboprops are overrated given modern turbofan engine performance. The speed penalty is just not worth it in most cases. This is noticeable in transport aircraft. I would rather have a Kawasaki C-2 rather than an Airbus A-400M or an Embraer KC-390 rather than a Lockheed C-130 Hercules. I think the Chinese Navy would have been better off designing a small two engine turbofan aircraft chassis and using it for multiple roles, from AWACS, to transport, refueling and anti-surface warfare like the US planned with the S-3 Greyhound replacement/S-3 Viking but limited powerplant choices might have led towards this way.
 
Last edited:

sheogorath

New Member
Registered Member
the S-3 Greyhound replacement/S-3 Viking but limited powerplant choices might have led towards this way.
There is the whole thing about those low hanging high-bypass turbofans being more susceptible to FOD. Plus the advantage of the turboprop offering longer loiter times since turboprops are more efficient than turbofans.

E-2 will routinely shut off one engine while on station to increase the times, which also comes handy if your plane doesn't have IFR capability.
 

crash8pilot

Just Hatched
Registered Member
As a pilot myself, just wanted to give my two cents.... a pair of CFM56 engines used on 737s and A320s (also used on the E-3 and newer versions of the KC-135, which might I add feature 4x CFMs) burn 2200kg per hour in minimum clean holding configuration (~200 to 230 knots, depending on aircraft load), whereas a pair of Pratt and Whitney turboprop engines on the Dash-8 that I used to fly burns 800kg per hour in the same clean configuration (~180 knots, a 737/A320 would have to dirty up the configuration with flaps and slats to fly/hold at such speed, which increases fuel burn). Not I'm most certainly not downplaying engine performance on modern turbofan engines, I'm just saying the fuel burn on a turbofan is almost 3x that of a turboprop.

Now of course I'm not drawing direct parallels because we just don't know all that much about the KJ-600. What I'm hypothesizing based on my experience flying turboprops is that they have better endurance, especially since in carrier ops you don't have to fly the distances AWACS platforms have to fly because the carrier already takes you to the doorstep of the battleground, and as such there is no need to cruise at higher speeds (certainly don't need to reach ~M.80 modern airliners cruise at). I do believe an AEW utilizing a turboprop platform is able to takeoff from a carrier, comfortably hold/loiter at low airspeeds as compared to a turbofan platform, while also burning less fuel at the same time.
 

Top