SinoDefence Forum

beijingcar

This is the first under belly picture of the JZ8F I knew of, I also think the wings on this J8F has a higher aspect ( wider, longer) ratio than J8IIB. Also the two things under the wings does not look like weapon rail, maybe ECM pods? take a look what you guys think?
Sorry, I deleted the picture, now it is on the second page

Or if you can read Chinese, the picture is in this sit: http://junshi.xilu.com/

Ryz05

That bump under the belly looks like some spying device. Is this a reconnaiscence plane?

RedMercury

JZ-8 is recon version of J-8I, this is the recon version of J-8F.

Schumacher

J-8's high speed & high ceiling make it a good recon plane. Has there been improvements to the range ? which has always been a main bottleneck.

beijingcar

I have always thought the J8F is using WP14 instead of WP13BII for their engines. Now is you look at this picture, then compare to pictures of J8IID, the size and the shape of the very end of the fuselage (exhaust tip) is different, so I think this J8IIF is powered by something other than WP13BII. If it is powered by 2 WP14s, then yes, you will get a faster jet and longer ranged as well.

planeman

The "things" under the wings aren't ECM, I think they're just weapons/stores pylons without any launch rails attached.

Sensor pack appears to include radar, engines are different bt can't see how the wings are any different.

RedMercury

J-8F is capable of aerial refueling.

goldenpanda

aren't turbojets supposed to be efficient at high altitude? The Chinese forums are saying the kunlun-3 will each have 5800kg DRY thrust, which will allow an upgraded J8F to supercruise.

http://bbs.tiexue.net/post_1640865_1.html

beijingcar

I meant by the wings look bigger than the J8IIB. I read sometimes ago ( last year, I think) that the F model is shorter than C and B by about 35cm. So that may be the reason for the wings to looks bigger. On the ECM pods, I thought them as weapon pylons as well till I saw there are little spikes about 1/3 in front of the "things". weapon pylons do not have them. Also having ECM pods on the JZ8F make sense to me because the J8F's internal ECM suit may not be powerful enough for enemy SAM radar suppression work since the JZ8F will act as a lone wolf and going into dangous and unknown airspace a lot more than regular fighters.
Also the sensor pack location is where the 23mm twin barrell cannon is located, so, i think the gun is gone for the JZ8F.
As for supercruise. The standard for supercruise is set by F22 at Mach 1.4 cruise speed. Even with a weight to max thrust ratio of 1:1.1 for the uprated J8F, for it to cruise for extended time at Mach 1 is difficult because you have to remember the jet weights in at 33000 LBs ( about 15000 KG) with internal fuel, plus you have to have on board weapons ( unlike the internal weapon storage for the F22) and a drop tank or two. All these added weight and drag will reduce the cruise speed.

crobato

Personally I don't think there is any change in the wingspan of the J-8F, mainly because the program is already on a shoestring budget, Changing the wings and so on would cost valuable development money. The benefits of a longer wingspan wing would have been small, as I don't really see that big a difference to make it worthwhile.

It you really wanted to improve the wing design, it would have been to go with a double delta layout, which would have raised wing aspect and wing span for better low speed maneuverbility and angle of attack. Add variable camber slats on the front edge and so on.

But while all this would have improved agility, these will be offset by increased drag, and the plane would be slower. Since the plane was intended as a high speed interceptor and not as a dogfighter, this was a matter of setting priorities what you want the plane's mission role should be. As primitive as it looks, hard edged wings with wing fence is faster than wing with variable camber slats on the front edge. The F-86 actually with hard wings with fences on later variants when earlier variants used slats.

Increasing wingspan would not have helped the J-8F on high speed mission roles. The only perceivable aerodynamic difference would be adding another fence to the wing.

I also think J-8F, at least with later versions are powered by Kunlun engines, although this may have been progressive. The J-8F/H probably started first with WP-13B in 2001, then transitioned to the Kunlun, and later to the even more powerful Kunlun II. As WP-13s meet the end of their life expectancy and as spares run out, the newer planes in the PLAAF J-8II fleet maybe transitioning and upgrading to Kunlun engines.

beijingcar

Hi Crobato: I thought by increase the wingspan you have resulted a smoother ride at low levels, I was told both J7 ( none E,G) and J8II have a very jittery ride at low level because of the delta wing design. For a fast tactical photo recon jetfighter like the JZ8F to survive in a modern battlefield, it has to have a strong ECM suit on one hand, and on the other hand, it's flight profile has to be extrem low level entry then zoom up fast to attitude, take the pictures, then drive down low again to get away. The old traditional way for a recon plane is high level and fast speed entry, then even faster speed and still higher attitude for get away. This old way in today's battlefield is a sure way to get yourself shotdown(killed). So, in a way, better flying qualities at low level for the JZ8F maybe is more important than regular J8IIF. So if they( SAC) increased the wingspan without change the shape, the jet will have a better ride at low level but at the same time high speed qualities suffered little. What do you think?

crobato

Actually, increasing wing span would have worsened your low level ride.

If you like a smooth low level ride, better with low wingspan and high wing loading. Of course the disadvantage to this is that it lengthens your take off and landing, making the plane more difficult to land.

The Starfighter with small, short wingspan wings, happens to be ideally for low level strike and reconnaissance missions, although the plane can do high altitude ones as well. Visualize this too, why variable wing fighters and bombers like F-111, MiG-27, Su-24, Tornado and B-1 all sweep their wings when they go low level.

beijingcar

I see, thanks man for the explaination. You are right, it make them no sense to change the wings, I must had too much to drink by thinking the wings looked bigger. I had seen a F104 up close and personal in Dayton Airforce Museum, i must say, I understand why they call it the missile with wings.

beijingcar

Crobato: I just used a ruler to measure the wing length of this new JZ8F picture in relation to the total length of the fuselage of this jet and compared to this picture of the J8IID, Take a look guys, either the F model a lots shorter( more than the 35cm) or the wing is bigger. What do you think?

beijingcar

sorry, I deleted the first pict of the JZ8F, better picture is in next post.