JF-17 Thunder Multirole Fighter [Thread 5]

[swati]

I already know of the topic..
I am basing my fuel idea on the Mig-21U.. which too has a dorsal spine that houses fuel.

In case of Mig 21 it houses the Flight control rods, not the fuel.

 

[air marshal]

Chinese military aircraft debut at Paris Air Show

Two-seat version of Xiaolong/FC-1B

The two-seat version of Xiaolong combat trainer FC-1B was developed on the basis of the same model of single-seat Xiaolong FC-1 with distinguished training functions while retaining most of the combat capabilities of the FC-1 at the same time. It is generally used for the refitting and flight training as well as tactical training of FC-1 pilots in peace time, and can also be used to perform combat missions in wartime. It is an important type of the Xiaolong series.

Chinese military aircraft debut at Paris Air Show - People's Daily Online

 

[air marshal]

 

[SQ8]

In case of Mig 21 it houses the Flight control rods, not the fuel.

On the trainer versions, internal fuel is carried in five bladder tanks inside the fuselage, a saddle tank and four integral tanks in the wings. This gave a total capacity of 2,350 litres (517 Imp gal) for the MiG-21 U and 2,450 litres (539 Imp gal) for the MiG-21 US/MiG-21UM. The fuselage tanks are pressurised to 0.21-0.23 kg/cm2 (3.0-3.28psi) and the wing tanks to 0.41-0.43 kg/cm1 (5.85-6.14 psi). - See more at: MiG-21 Fuel system and tank capacity

The flight control rods dont take up a foot diameter even with the hydraulic rams even on this early Mig-21U. In fact with a similar dorsal or "saddle" tank the control rods pass right through this particular tank on the spine.

Now, when you refer to control rods.. or avionics it would make sense if the hump was relatively smaller. But the cutaway shows that the control rods go Above a smaller dorsal tank that sits there to augment some of the lost capacity.
Look at this image of a plain F-13.. look at where the control rods are going within that small space.

..clearly.. control rods dont need a cavernous space such as that. To further that... here is a Mig-21MF.. that also has a hump.. except in this case it does house the extra avionics needed.

Now, based on the JF-17 model.. here is the A-10 in two variants.. the single seater A-10.. and the Night and Adverse weather variant.

Notice how with the seat.. the fuel capacity has been eaten up.. but the avionics that took up the space behind the cockpit have been put neatly away in the space for fuel(but not as much to occupy a Hump).. the same goes for the F-16B or even the F-5B.

So, UNLESS.. the JF-17 Dual seater is:
A.packing more than the usual Avionics Package.
B. Not eating into the Fuselage tanks

Either the model in inaccurate.. or the engineers within Chengdu are Daft and giving a dog the size of an elephant room.
Either way.. My whole disagreement IS on the basis of the size of the hump. If it were smaller than that.. say the type you see on the Gripen(which has comparable avionics that sit behind the pilot)...I'd be saying the same thing.
If you look at the normal JF-17.. it too has a small spine that is there to accommodate any linkages or pipes.

I am not claiming to have accurate knowledge on what the JF-17 has in there, but I cannot go with your theory because it disagrees with what my eyes see.

 

[Rajput_Pakistani]

One reason for "Raised Spine" is because in 2 seat versions, back seat is raised a little. Around 10-15 Inches. Baqi jo marzi theories lagatay raho. Obviously when little more space is available, you can house more fuel or avionics there.

 

[MuZammiL Dr. s[1]n]

Yar they banned me....b/c I was kicking bhartisss' ugly kaali arses too much

same has been going on with me right since i joined here ...

 

[Gentelman]

same has been going on with me right since i joined here ...

let admin do that so that they get their right place by being banned……

 

[Major Sam]

let admin do that so that they get their right place by being banned……

Thats why more indian posts as compare to paksitanis its like Pakistan Defending Forum. Rather than Defence Forum

@auz

 

[swati]

The flight control rods dont take up a foot diameter even with the hydraulic rams even on this early Mig-21U. In fact with a similar dorsal or "saddle" tank the control rods pass right through this particular tank on the spine.

Clearance Issues for control rods + Electrical harnesses (Mig 21) (It is not advisable to dip control rods in fuel, This creates maintenance issues and some other issues)


Now, when you refer to control rods.. or avionics it would make sense if the hump was relatively smaller. But the cutaway shows that the control rods go Above a smaller dorsal tank that sits there to augment some of the lost capacity.
Look at this image of a plain F-13.. look at where the control rods are going within that small space.

Agreed. In Mig 21 the area below the hump or spine ( basically the Center Fuselage area) houses fuel but there is no fuel in the spine itself. As far as the saddle tank is concerned yes it is there but only in a few variants. Not in all variants. Rest all other use them for avionics. (see the Mig 21 Bison to have an idea of the measures taken for increasing space for avionics)


.clearly.. control rods dont need a cavernous space such as that. To further that... here is a Mig-21MF.. that also has a hump.. except in this case it does house the extra avionics needed.

Glad you came up with that.

Now, based on the JF-17 model.. here is the A-10 in two variants.. the single seater A-10.. and the Night and Adverse weather variant.

Notice how with the seat.. the fuel capacity has been eaten up.. but the avionics that took up the space behind the cockpit have been put neatly away in the space for fuel(but not as much to occupy a Hump).. the same goes for the F-16B or even the F-5B.

Yes but they learned through further aerodynamic analysis that if you create a spine then the increase in drag (and parasitic drag if you say it is behind the cockpit) is not to a very great amount. Shortly it was the design requirement to not decrease the fuel capacity in later models of F-16 and still house the same avionics as the single seat model.

So, UNLESS.. the JF-17 Dual seater is:
A.packing more than the usual Avionics Package.
B. Not eating into the Fuselage tanks

Avionics package is usually the same for same block single seat and dual seat models.
As far as point B is concerned if i were the designer i would either:
1. Decrease the fuel capacity and house the avionics there (the ones displaced by the second seat.
2. Leave the tanks alone and house the avionics in a dorsal spine. (This option is much easier to adopt)

Either the model in inaccurate.. or the engineers within Chengdu are Daft and giving a dog the size of an elephant room.
Either way.. My whole disagreement IS on the basis of the size of the hump. If it were smaller than that.. say the type you see on the Gripen(which has comparable avionics that sit behind the pilot)...I'd be saying the same thing.
If you look at the normal JF-17.. it too has a small spine that is there to accommodate any linkages or pipes.

I am not claiming to have accurate knowledge on what the JF-17 has in there, but I cannot go with your theory because it disagrees with what my eyes see.

Who said anything about theory?
The model seems to abide by the rules. And what your eyes see is an F-16 D with a huge spine housing only avionics displaced by the rear cockpit and you still choose not to accept the modern day trends.

Shortly there is no fuel there. You seem desperate to increase the range of the aircraft and the more the better is what i would like too. But just let this one pass. Rest its your choice you may still disagree.

 

[swati]

One reason for "Raised Spine" is because in 2 seat versions, back seat is raised a little. Around 10-15 Inches. Baqi jo marzi theories lagatay raho. Obviously when little more space is available, you can house more fuel or avionics there.

Agreed....

 

[Gentelman]

Thats why more indian posts as compare to paksitanis its like Pakistan Defending Forum. Rather than Defence Forum

@auz

its our bad luck mate actually that we have to tolerate such peiple who are just here to ruin the discussion……
well are H-4 & H-2 BVR bombs integrated with JFT if they are then why they are not on any of ariel display and why so much secracy is being kept??
JFT needs more powerful radar and engine these are two basic needs for 2 seater which are missing…

 

[araz]

its our bad luck mate actually that we have to tolerate such peiple who are just here to ruin the discussion……
well are H-4 & H-2 BVR bombs integrated with JFT if they are then why they are not on any of ariel display and why so much secracy is being kept??
JFT needs more powerful radar and engine these are two basic needs for 2 seater which are missing…

People need to understand that the forum has rules and in your exuberance a lot of our junior colleagues cross the limits and become abusive or disruptive. This is what earns you a ban. Dont get abusive get realistic and argue with knowledge.
Araz

 

[SQ8]

The flight control rods dont take up a foot diameter even with the hydraulic rams even on this early Mig-21U. In fact with a similar dorsal or "saddle" tank the control rods pass right through this particular tank on the spine.

Clearance Issues for control rods + Electrical harnesses (Mig 21) (It is not advisable to dip control rods in fuel, This creates maintenance issues and some other issues)


Now, when you refer to control rods.. or avionics it would make sense if the hump was relatively smaller. But the cutaway shows that the control rods go Above a smaller dorsal tank that sits there to augment some of the lost capacity.
Look at this image of a plain F-13.. look at where the control rods are going within that small space.

Agreed. In Mig 21 the area below the hump or spine ( basically the Center Fuselage area) houses fuel but there is no fuel in the spine itself. As far as the saddle tank is concerned yes it is there but only in a few variants. Not in all variants. Rest all other use them for avionics. (see the Mig 21 Bison to have an idea of the measures taken for increasing space for avionics)


.clearly.. control rods dont need a cavernous space such as that. To further that... here is a Mig-21MF.. that also has a hump.. except in this case it does house the extra avionics needed.

Glad you came up with that.

Now, based on the JF-17 model.. here is the A-10 in two variants.. the single seater A-10.. and the Night and Adverse weather variant.

Notice how with the seat.. the fuel capacity has been eaten up.. but the avionics that took up the space behind the cockpit have been put neatly away in the space for fuel(but not as much to occupy a Hump).. the same goes for the F-16B or even the F-5B.

Yes but they learned through further aerodynamic analysis that if you create a spine then the increase in drag (and parasitic drag if you say it is behind the cockpit) is not to a very great amount. Shortly it was the design requirement to not decrease the fuel capacity in later models of F-16 and still house the same avionics as the single seat model.

So, UNLESS.. the JF-17 Dual seater is:
A.packing more than the usual Avionics Package.
B. Not eating into the Fuselage tanks

Avionics package is usually the same for same block single seat and dual seat models.
As far as point B is concerned if i were the designer i would either:
1. Decrease the fuel capacity and house the avionics there (the ones displaced by the second seat.
2. Leave the tanks alone and house the avionics in a dorsal spine. (This option is much easier to adopt)

Either the model in inaccurate.. or the engineers within Chengdu are Daft and giving a dog the size of an elephant room.
Either way.. My whole disagreement IS on the basis of the size of the hump. If it were smaller than that.. say the type you see on the Gripen(which has comparable avionics that sit behind the pilot)...I'd be saying the same thing.
If you look at the normal JF-17.. it too has a small spine that is there to accommodate any linkages or pipes.

I am not claiming to have accurate knowledge on what the JF-17 has in there, but I cannot go with your theory because it disagrees with what my eyes see.

Who said anything about theory?
The model seems to abide by the rules. And what your eyes see is an F-16 D with a huge spine housing only avionics displaced by the rear cockpit and you still choose not to accept the modern day trends.

Shortly there is no fuel there. You seem desperate to increase the range of the aircraft and the more the better is what i would like too. But just let this one pass. Rest its your choice you may still disagree.

1. I did not suggest that you dip control rods in fuel.. neither does the cutaway suggest that. I suggest a smaller saddle tank that came as part of the added structure. And You do agree that the saddle tanks exist on many variants.

2. The parasitic drag explanation is much better in this context and is more convincing, because then it explains away why certain aircraft that do have two seater variants where there is little change in terms of shape behind the cockpit. Since the addition of the seat does not have significant effect on the form drag. In case of the JF-17 dual seater.. with its rear seat raised above there is going to be increase in parasitic drag.

3. I am far from desperate to increase fuel.. I was more desperate to explain the disproportionate increase in the size of the spine as compared to what you commented was in it. As for the F-16, it would make sense for a spine that large with the sophistication of the equipment it carries. Why that narrative did not seem to fit for the JF-17 is the relative space that the avionics seem to occupy. Hence, the disagreement until you came up with a more plausible explanation than avionics size or otherwise.

 

[swati]

1. I did not suggest that you dip control rods in fuel.. neither does the cutaway suggest that. I suggest a smaller saddle tank that came as part of the added structure. And You do agree that the saddle tanks exist on many variants.

2. The parasitic drag explanation is much better in this context and is more convincing, because then it explains away why certain aircraft that do have two seater variants where there is little change in terms of shape behind the cockpit. Since the addition of the seat does not have significant effect on the form drag. In case of the JF-17 dual seater.. with its rear seat raised above there is going to be increase in parasitic drag.

3. I am far from desperate to increase fuel.. I was more desperate to explain the disproportionate increase in the size of the spine as compared to what you commented was in it. As for the F-16, it would make sense for a spine that large with the sophistication of the equipment it carries. Why that narrative did not seem to fit for the JF-17 is the relative space that the avionics seem to occupy. Hence, the disagreement until you came up with a more plausible explanation than avionics size or otherwise.

1. I didn't say many i said few.

2. I incorrectly mentioned parasitic drag. I should have referred Skin Friction drag.

3. And this is just a model. Lets wait and see if they put a fuel tank or use it for avionics.

 

[SQ8]

1. I didn't say many i said few.

2. I incorrectly mentioned parasitic drag. I should have referred Skin Friction drag.

3. And this is just a model. Lets wait and see if they put a fuel tank or use it for avionics.

1.Considering that the MiG-21 PF/MiG-21PFS, MiG-21PFM and MiG-21FL ,MiG-21 R, MiG-21 S/MiG-21M and MiG-21 SM/MiG-21MF,MiG-21 MT and MiG-21 SMT all used saddle tanks.. I believe thats more than few. But as you wish.

2.Isnt Skin Friction, Form considered a part of parasitic drag?? i.e the drag due to the object moving through the fluid?

3. Yes.. which is why the physical dimensions of the model lead to the fuel argument.