China Military Watch

[Indranil]

Check out this pic, it definitely doesn't look swept back. I think it's very possible that it has the exact same shape as the main wings.

Look at this pic.


I think the canards are at a negative AoA. You can see the trailing edge at the top. If the canards are at positive AoA the trailing edge is at the bottom. In either cases you can see that they are not straight. I believe the trailing edges of the wing and the canard are edge aligned. I believe that there is a sweep, albeit small.

The reason I doubt that the leading edges of the canard and the leading edge of the wing is not aligned is because of the chord of the wing and the canard. The canard is close to 40% of the wing by span. If they had the same angle for the leading edges, the chord of the canard would be 40% of the chord of the wing, which it is clearly not.

[andy B]

^^^ okies me no aero injuneer so bear with me...

doesnt positive aoa have to do with a pitching up movement or basically going up while negative aoa is experiened while suddenly going down like a free fall and the movement of the control surfaces will be:

-if the plane is pitching up these control surfaces will be such that the leading edge will be up
-if ze plane is pitching down then it will be what the above pic shows i.e. negative aoa...

would be great if you could confirm thanks....

[DavidD]

I don't think so, this plane is designed to be an air superiority fighter first and foremost. If, and that's a big if, China can put the WS-15 in there, then there's no reason why it can't tango with anyone. It has a large lifting body, good wing area(the PAK-FA has small wings too, it just has a wider body so it has a bigger wingspan. It relies much heavier on the lifting body which produces far less lift per area than wings.), and canards, so aerodynamically, it might be the best of all 3 current 5th gen fighters/prototypes. Can you give me some reason why it wouldn't?

Because it will also produce the most drag of all these 3 designs with all that wetted area, which seems to be more than the other two designs.. To be anything as maneuverable as the T-50 or F-22 it needs very high thrust engines, and even then its STR will be lower than the other two with such a large wing and internal volume.

It's possible that it'll be less maneuverable, but it almost certainly won't be due to "all that wetted area". The T-50 has a much wider body and thus probably have the most wetted area of the 3 designs. It's a basic geometric principle, the more tubular/spherical something is, the less surface area it has for a given volume, and vice versa. If the J-20 has more wetted area than the T-50, given its much narrower body, then its internal volume must be much greater.

For example, if you make the thinnest(top to bottom) plane possible, you'd have something that looks like 2 sheets of paper laid on top of each other. It would have a gigantic wetted area and practically 0 internal volume. If you make the plane tubular with the same wetted area, you'd have massively increased internal volume. That's why missiles are tubular.

Check out this pic, it definitely doesn't look swept back. I think it's very possible that it has the exact same shape as the main wings.

Look at this pic.


I think the canards are at a negative AoA. You can see the trailing edge at the top. If the canards are at positive AoA the trailing edge is at the bottom. In either cases you can see that they are not straight. I believe the trailing edges of the wing and the canard are edge aligned. I believe that there is a sweep, albeit small.

The reason I doubt that the leading edges of the canard and the leading edge of the wing is not aligned is because of the chord of the wing and the canard. The canard is close to 40% of the wing by span. If they had the same angle for the leading edges, the chord of the canard would be 40% of the chord of the wing, which it is clearly not.

I think the leading edges are aligned, but I don't think the trailing edge is swept back. I think the canard will look similar to the main wings in that the trailing edge is slightly curved forward. That picture you posted supports my guess.

As for the AOA, it can be adjusted, or do you mean that they're dihedral?

[wrdos]

A new rumor.

Somebody identified a B737 plane arrived at CAC airport, Chengdu, a sign of some visiting very top VIPs.

Maiden flight this afternoon?

[DavidD]

So, it seems that internet rumors are right that this plane will have its first flight today, probably in the afternoon. According to news out of China, the PLA commander has arrived along with CCP bosses(last time was just the chief of the PLAAF). Unfortunately, we may not get early leaks from cellphone pics, as all major roads leading to CAC has been sealed and guards have surrounded the complex. They'll probably do like the Russians and release something only after a successful first flight.

[Indranil]

I think the leading edges are aligned, but I don't think the trailing edge is swept back. I think the canard will look similar to the main wings in that the trailing edge is slightly curved forward. That picture you posted supports my guess.

As for the AOA, it can be adjusted, or do you mean that they're dihedral?

No, I am not speaking of the dihedral.

Lets wait for some planform pictures then

[DavidD]

I think the leading edges are aligned, but I don't think the trailing edge is swept back. I think the canard will look similar to the main wings in that the trailing edge is slightly curved forward. That picture you posted supports my guess.

As for the AOA, it can be adjusted, or do you mean that they're dihedral?

No, I am not speaking of the dihedral.

Lets wait for some planform pictures then

Hopefully even better than pictures! CCTV(the official government channel) crews are in CAC, and if things work out we should see clear videos soon

[Indranil]

^^^ okies me no aero injuneer so bear with me...

doesnt positive aoa have to do with a pitching up movement or basically going up while negative aoa is experiened while suddenly going down like a free fall and the movement of the control surfaces will be:

-if the plane is pitching up these control surfaces will be such that the leading edge will be up
-if ze plane is pitching down then it will be what the above pic shows i.e. negative aoa...

would be great if you could confirm thanks....

Hi Andy, I am no aero engineer either .

A positive AOA of the canard has a pitch-up effect of the nose. In this case the leading edge is higher than the trailing edge.
Negative AoA is the opposite.

However, in that particular picture, the canard seems to be working as an air brake (since the drag grows with magnitude of AoA). As an air brake on the ground, you would like to push the plane to the ground for better friction (by increasing normal force like in an F1 car). So you would like to push the nose down, hence negative AoA of canard.

[andy B]

^^^ okies me no aero injuneer so bear with me...

doesnt positive aoa have to do with a pitching up movement or basically going up while negative aoa is experiened while suddenly going down like a free fall and the movement of the control surfaces will be:

-if the plane is pitching up these control surfaces will be such that the leading edge will be up
-if ze plane is pitching down then it will be what the above pic shows i.e. negative aoa...

would be great if you could confirm thanks....

Hi Andy, I am no aero engineer either .

A positive AOA of the canard has a pitch-up effect of the nose. In this case the leading edge is higher than the trailing edge.
Negative AoA is the opposite.

However, in that particular picture, the canard seems to be working as an air brake (since the drag grows with magnitude of AoA). As an air brake on the ground, you would like to push the plane to the ground for better friction (by increasing normal force like in an F1 car). So you would like to push the nose down, hence negative AoA of canard.

Okies thanks for that reply completely understand I was a bit confused about my understanding of what position would the said control surface be in when pitching up and pitching down and from your reply I can see that my understanding is right Phew!!!

Now coming to the pic saar I think that the canards are pitching up in this particular instance the reason i say this is because if you look at the canard front and rear shape they are clearly different and if the canard was pitching down you would have the straighter end part going up instead we have the front inclined part going up (hope that makes some sort of sense its a bit hard to explain with just words)

what do you think???

[Indranil]

Its not just the wetted area, the wave drag on the J-20 will most probably be the highest amongst the 3 "5-G" planes. T-50 has one of the lowest wave drag in its class of fighters and is reportedly less than Su-27 airframe. It is easy to see why.

With a box frame, the area ruling goes for a toss at the starting of the box as the cross sectional area grows rapidly. Besides the rate of growth of cross-section area along the longitudinal axis at the nose is very big for the J-20. This is not good for wave drag. After the intake lips, the cross sectional area increases slowly with the canard and then falls back again at the end of the canard (there will be no jerks here, but this will be a departure from the Sears-Haack body). Then once again there will be a nice growth along the wing but the back part will see a very sharp fall in area again. This partially is the reason of the big hydraulic housing (terrible for RCS). This is in common with the LCA (and we read about how they were planning to tackle that problem).

However, I don't believe that this plane is a bomb truck. It will be maneuverable but not exactly agile. I think part of the reason for the plane to have canards with such a large span and dihedral is because it is dual purpose. Not only does it creates vortices for the top of the wing, but it creates vortices for the stout rudders which at high AoA will be hidden behind the huge body and delta wing. This will give it yaw-authority at high AoA. I think the canards were a requirement and hence the RCS was compromised.

In terms of kinematics the F-22 and the PakFA will be clearly ahead. The engine is going to be so critical for this plane. Actually with this airframe it will be sluggish around the corners. Unless the Chinese get the engines right on this one, it will be the Achilles heal of this plane.

The fact that PAKFA has a kinematic advantage over the F-22 is a well known fact.

[Indranil]

Hi Andy, I am no aero engineer either .

A positive AOA of the canard has a pitch-up effect of the nose. In this case the leading edge is higher than the trailing edge.
Negative AoA is the opposite.

However, in that particular picture, the canard seems to be working as an air brake (since the drag grows with magnitude of AoA). As an air brake on the ground, you would like to push the plane to the ground for better friction (by increasing normal force like in an F1 car). So you would like to push the nose down, hence negative AoA of canard.

Okies thanks for that reply completely understand I was a bit confused about my understanding of what position would the said control surface be in when pitching up and pitching down and from your reply I can see that my understanding is right Phew!!!

Now coming to the pic saar I think that the canards are pitching up in this particular instance the reason i say this is because if you look at the canard front and rear shape they are clearly different and if the canard was pitching down you would have the straighter end part going up instead we have the front inclined part going up (hope that makes some sort of sense its a bit hard to explain with just words)

what do you think???

It definitely could be. May be the plane was not using it as a airbrake. May be the pilot was just checking the functionality. It might be that the canards are at positive AoA in this pic. My point in the discussion was that the trailing edge is not straight.

David has the opinion that
1. The canard is not swept back
2. Leading edge of canard and the wing are edge aligned
3. Trailing edge of atleast the canard swept forward (may be edge-aligned with the trailing edge of the wing)

My contentions are
1. The canard is slightly swept back
2. Leading edge of canard and the wing are not edge aligned
3. Trailing edge of the canard is actually swept back (obviously if 1 is true) and is most probably edge aligned with the trailing edge of the wing.

In addition I feel that in the C-G rendition (that David provided) the outer edge of the wing is not correct. I believe, it will be edge aligned with the outer edge of the canard. If not, I would be very dissapointed with this design in terms of RCS reduction.

We are both waiting for planform pics/videos.

[prithvi]

Credit should be given where it is due... Chinese have really shown some good rapid prototyping from design board to a real flying aircraft... even it does not get operationalize... in next 5 years.. it will simply be a good deterrent factor... I wish we could have done the same for Arihant... !!

[wrdos]

Now it is almost clear that the J20 will make its maiden flight in hours if not minutes. On Chinese military websites, some on-site guys are reporting the progress minute by minute in fact.

Let's wait and see.

[wrdos]

Updated,

The pilot just arrived at the site.

[wrdos]

Updated

The pilot is now on the plane

[GuruPrabhu]

Updated

The pilot is now on the plane

Updated

Test pilot says Hail Mao

[wrdos]

Updated 14:27 Chinese time

The engine of the J20 started

[naren]

May be all these "anonymous" photos are an elaborate Kim-Kardashian-sex-tape-ish PR stunt by PRC ?

[wrdos]

I just made a mistake by posting a test document.
I am very sorry and I have deleted it already.

Breaking News!
The J20 just departed for its maiden flight.
Time 14:30, Jan. 6, 2011.

Hope the pilot lands safely. For the sake and health of the families of all scientists, pilots, technicians, and other involved propogandists.

[wrdos]

Updated

The pilot has left the plane.
Maybe today is not the day?

[csharma]

Great achievement by China in getting to this stage so fast. Congratulations.

[Dileep]

Why am I not surprised wrdos? Just like the draft news of a space launch got accidentally published!

[ordos]

Updated 14:27 Chinese time

The engine of the J20 started

Updated 15:30 Chinese time

The Test Pilot of the J20 just farted. Today was indeed THE day

[kvraghav]

Arrival of the pilot to sitting in the plane post takes 2 mins, then to start of the engine post takes 2 mins.Come on mods,should we tolerate this nonsense anymore???

[Philip]

China's fast route to success...copycat tech,through steal-ing!

J-20 stealth fighter: China 'leaks' pictures of stealth fighter jet test run
China's first stealth fighter jet staged a runway test on Wednesday and could undergo its first flight on Thursday, according to Chinese media reports.

http://www.telegraph.co.uk/news/worldne ... t-run.html

By Malcolm Moore 6:00AM GMT 06 Jan 2011
Both the English and Chinese language editions of the Global Times ran front-page articles on the leaked photos of a J-20 fighter, along with extensive reports on the buzz the pictures have generated overseas.

Photos of the plane appeared on unofficial military news websites and hobbyist blogs last week and were still viewable on Wednesday.

The Global Times did not comment on the authenticity of the pictures, but since the government wields extensive control over state media, the report's appearance and the fact that censors have not removed images from websites suggest a calculated move to leak the information into the public sphere.

That in turn would reflect the growing confidence of the traditionally secretive People's Liberation Army, which is pushing for greater influence and bigger budgets.

Calls to the spokesman's office at the Defense Ministry rang unanswered on Wednesday.

Related Articles

China 'leaks' pictures of stealth fighter jet test run06 Jan 2011

Aviation websites said the photos were taken from outside a fence at the Chengdu Aircraft Design Institute's airfield in southwestern China. The plane appeared to be undergoing a taxiing test of the sort that precedes an actual flight test.

China has seen the development of its own stealth fighter as a priority since the mid 1990s and He Weirong, the deputy air force head, told Chinese Central Television in November 2009 that a "fourth-generation" fighter would begin flight testing in 2010/2011 and enter service in eight to ten years.

China's aviation industry – both military and civilian – has made rapid progress in recent years but still relies heavily on imported technology. Propulsion technology has been a particular problem, with Russian engines still employed on China's homemade J-10 fighter jets and the J-11, a copy of Russia's Su-27 fighter jet.

Stealth technology is even more difficult to master because it relies on systems to hide the presence of the plane while equipping the pilot with enough information to attack an enemy. Emissions must be hidden and the plane's fuselage sculpted to avoid detection by radar and infrared sensors.

Chinese progress in that field calls into question U.S. Defense Secretary Robert Gates' decision to cap production of the F-22 Raptor stealth fighter at 187 planes. Supporters of the F-22 have warned of growing threats from China, as well as Russia, which has developed a stealth prototype that is already in the test flight stage.

Analysis of the J-20 photos shows it to be larger than either the Russian or U.S. planes, likely allowing it to fly further and carry heavier weapons.

There were also unanswered questions about persistent cyber-attacks in 2006 – around when the J-20 fighter programme was started – on US military contractors working on American fighters.

Between 2009 and early 2010, Lockheed Martin found that "six to eight companies" among its subcontractors "had been totally compromised, emails, their networks, everything," according to Anne Mullins, the company's Chief Information Security Officer. Meanwhile, analysts said that while the J-20 is larger than the F-22, it bears an uncomfortable resemblance to the US jet.

[Austin]

Its not just the wetted area, the wave drag on the J-20 will most probably be the highest amongst the 3 "5-G" planes. T-50 has one of the lowest wave drag in its class of fighters and is reportedly less than Su-27 airframe. It is easy to see why.

Indranil ,since J-20 and F-22 like design generated most of the lift from its wing and T-50/Flanker type generates lift from the body and wing with its lifting body design ( and integrated aerodynamic layout by Sukhoi )

What are the disadvantage of lifting body design over design like J-20/F-22 that uses classic wings for lift ?

[Lalmohan]

Arrival of the pilot to sitting in the plane post takes 2 mins, then to start of the engine post takes 2 mins.Come on mods,should we tolerate this nonsense anymore???

oh come on, be a sport! its hillarious to watch the wetting of chong sams in anticipation, just like we like our lungi dancing. i'm enjoying all the draft releases at T+8 mins as per Xinghua SOP

[Arya Sumantra]

What are the disadvantage of lifting body design over design like J-20/F-22 that uses classic wings for lift ?

If the fuselage body also generates lift besides the wings then isn't it a constraint for fuselage side profile shape? Merely a flat underbelly will not make fuselage lift-generating. Just like the wing's cross-section, the longitudinal cross section of fuselage will now have to be shaped, optimized for lift which will be affected by the profile of bubble canopy, its location, contour profile of rest of fuselage in side profile etc. As opposed to a wing-lift-only design where fuselage shape is only drag minimized, here there would be additional restrictions too, isn't it?

JMT

[Singha]

youtube videos are now uploaded of high speed taxi runs.

[kit]

Since it looks like an F22 it is no use denying the psycological impact favoring Chinas technological prowess.Apart from that the J 20 could as well find a place in PAF in about a decade probably less.The amount of weapons it can carry as well as the space for radar indicates it probably hold it own against the Su 30 and the MMRCA as well, if the avionics and weapons fit come anywhere near world class.
Now the Indian MCA is not thought of as an stealth design, and the only way to deal with the J 20 would be to have a stealth fighter of western standard, at least a JSF class.What would be or should be the Indian response in such a situation ? It might not be possible to get a true assessment of the J20 unless in actual combat., since I dont see the J20 participating in a Redflag !

[Viv S]

Since it looks like an F22 it is no use denying the psycological impact favoring Chinas technological prowess.Apart from that the J 20 could as well find a place in PAF in about a decade probably less.The amount of weapons it can carry as well as the space for radar indicates it probably hold it own against the Su 30 and the MMRCA as well, if the avionics and weapons fit come anywhere near world class.

Unlikely, unless they go through a major economic revival. As things stand they're hoping to somehow buy 36 J-10s by 2015, well over a decade after it entered service. And even that will probably require the Chinese to advance them a line of credit.

[Singha]

or give them refurbished older J-10s from first tranche.

[Pratik_S]

Since it looks like an F22 it is no use denying the psycological impact favoring Chinas technological prowess.

How can you say that China is technologically superior ? I don't think copying shows a countries technological prowess. Engg students can manage to copy the F-22 and make their own RC F-22.

[prithvi]

Credit should be given where it is due... Chinese have really shown some good rapid prototyping from design board to a real flying aircraft... even it does not get operationalize... in next 5 years.. it will simply be a good deterrent factor... I wish we could have done the same for Arihant... !!

What relation does the development of a nuclear submarine have to a strike aircraft? Stupidity abounds in good measure.
Are you Chinese as well?

Arrogance and I am the know all kind of attitude will only limit your relevance to a forum only... I am very much an Indian....lolz...

development of a nuclear submarine ... or a strike aircraft have a lot of relation from psy-ops standpoint ..thats why J-20 featues in CNN International...home page and not Arihant...not sure whether you will get that .. nevermind.. keep your keyboard inspired arrogance to yourself...

[Singha]

^

[Lalmohan]

both J20 and AshBM are being seen by mango goras as statements of intent by the dragon and have therefore served their propaganda value purpose, regardless of actual capability
a blow has been struck by dragon to spread fear amidst christendom
only the perfidious yindoo remains unfazed

[shiv]

Since it looks like an F22 it is no use denying the psycological impact favoring Chinas technological prowess.Apart from that the J 20 could as well find a place in PAF in about a decade probably less.The amount of weapons it can carry as well as the space for radar indicates it probably hold it own against the Su 30 and the MMRCA as well, if the avionics and weapons fit come anywhere near world class.
Now the Indian MCA is not thought of as an stealth design, and the only way to deal with the J 20 would be to have a stealth fighter of western standard, at least a JSF class.What would be or should be the Indian response in such a situation ? It might not be possible to get a true assessment of the J20 unless in actual combat., since I dont see the J20 participating in a Redflag !

What should be the Indian response? Shiver in our dhotis of course. And brown our langotis.

er why is a stealth plane needed to counter a stealthy aircraft. That is a naive idea that I keep hearing. The counter to one stealthy aircraft does not have to be another stealthy aircraft. How can a stealthy aircraft defeat another stealthy aircraft? Would an F-117 beat up an F-22? Why wouldn't an MKI or a MiG 35 beat up a B2?

[Samay]

http://www.youtube.com/watch?v=FgEANwpFc5o

[Lalmohan]

for those of us unable to view youtube from behind deewar-e-aag, please provide a short description of what delights might await us beyond the portal...

[Singha]

nothing much so far ... just footage of high speed taxi runs...it lifts the nose then slows down and deploys the parachute.