JF-17 Thunder Multirole Fighter [Thread 6]

[IrbiS]

 

[IrbiS]

It has many times crossed my mind. I don't think that Thunder has an onboard oxygen generator.

 

[Tempest II]

It has many times crossed my mind. I don't think that Thunder has an onboard oxygen generator.

I think that the maximum flight time could be catered for by bottles. Now that they have added IFR, onboard oxygen generator might come too.

 

[IrbiS]

I think that the maximum flight time could be catered for by bottles. Now that they have added IFR, onboard oxygen generator might come too.

We'll see

 

[Jungibaaz]

Nope, its JF-17 block-52 Raptor.

Source please?

Extra lift can be achieved by other means as well not just by increasing airframe and wing design. e.g . Flaps / slats.
Bigger wing is typically required for more fuel storage and payload.

The extra lift is partly what the LERX are there for. But that's not it's only purpose, and it isn't just surface area alone we're talking about.

 

[Dazzler]

it has an onboard oxygen generator, french, integrared as a ECS component.

 

[Tempest II]

 

[HRK]

 

[HRK]

 

[raahaat7]

@WebMaster why have the posts on this website become invisible to me. I can only see the quotes and names of the posters. Please help.

 

[gambit]

SDF's Deino speaks.
--------------------------

@Irfan Baloch extending the wings a bit would allow a pair of additional hard points. It would also improve certain performance metrics. But increasing the wing area would weaken low altitude performance and burden the current engine to a point where some of its combat edge would be eroded and impact its survivability.

NOW THIS, MY DEAR, IS IMPORTANT BIT

and like other "experts" here on the forum, I will pretend that I understand

and maybe the justification for the current dimension more like (apologies for the lack of correct analogy) the length of the barrel of a gun is only feasible to a point until it no longer provides any further range or velocity bonus to the projectile.

@Oscar @MastanKhan @gambit do you concur?

I have never design a wing. Alongside sensor, I was also an avionics specialist, specifically in processes and sub-systems integration engineering, meaning I do what it takes to make many things work together and whatever does not play well with other, I send it back to the owner. But that does not mean I do not have to know how things should be at least at the design level.

Regarding enlarging the JF-17's wings. It is not as simple as enlarging the surface area.

Let us take the wing itself for now.

The wing produces three main items: lift, drag, and pitching moment. To maximize lift, drag and pitching moment must be minimized. In designing a wing, especially before the age of computer simulations, a design may unintentionally have high drag or high pitch down moment but the designer would not know that until wind tunnel testing or even later -- flight models. Hopefully not manned models, but such tragedies have happened before.

Most important thing to remember: No aircraft is ever without a specific purpose, including the designs that are supposedly 'multi-role'.

The words 'multi-role' is highly misleading when it comes to aircraft designs. The words 'multi-role' indicate the end user's intentions. The C-5 can drop bombs if the desire is there. Not as efficient as the WW II era B-25, of course, but the C-5 certainly can be used to drop bombs. So what the aircraft designer must do is to solicit as accurately as possible the overall purpose of the aircraft from the customer and come up with a wing best suit for that purpose. Humans and bombs are cargo. For the wing designer, how the end user intends to deliver either humans or cargo is none of his concern. All he needs to know is that his wing must lift a type of aircraft. From that, he begins his work.

How many wings does the C-130 and the 767 have ? Believe it or not, each aircraft have only ONE wing. Yes, the C-130, C-5, 747, and the 767 each have only one wing. The C-130 and the C-5 are 'high wing' designs. The Boeings are 'low wing' designs. Being 'high wing' or 'low wing' have its own advantages and disadvantages. The wing may be structurally separable into sections, but aerodynamically speaking, either 'high wing' or 'low wing' are unitary, even if there may be some fuselage blending effect.

For the C-130 and C-5, non-human cargo are priority so ease of loading them leads the aircraft designer towards the 'high wing' design. For Boeing, the priority is human cargo. The 'low wing' will experience ground effects sooner, which make for better take-off performance. The 'low wing' design will also have much less downwash on the tail section, making the tail section more effective in producing stable flights and maneuvers, which translate to a much smoother flight experience. There are plenty more information on the differences and preferences between the two types. Suffice for now that the vertical location of the wing assembly, above or below the fuselage, already set the tone for the wing designer.

How many wings does the F-104 Starfighter have ? Two. Yes, the F-104 Starfighter have two wings. So does the WW II era F-4 Wildcat. In this design, the wings are aerodynamically and physical distinct structures from each other. They are separated by the fuselage. These two aircrafts have the 'mid wing' design. The F-16 is a 'mid wing' design with high fuselage blending.

How many wings does the biplane have ? Two. Yes, the biplane have two wings, or more precisely two aerodynamically and structurally distinct wings. In the case of the Antonov An-2, one wing is fuselage high and one wing is fuselage low. In the case of the WW I era Sopwith Camel and many other biplane designs of the same era, the low wing is fuselage low and the top wing is called a 'parasol wing'. A 'parasol wing' design is when the fuselage is attached to the underside of the wing thru struts.

Parasol wing - Wikipedia, the free encyclopedia

A parasol wing monoplane is an aircraft design in which the wing is not mounted directly to the fuselage, but rather, the fuselage is supported beneath it by a set of struts, called cabane struts.

Some designers may take issues with the argument that the Sopwith Camel have a parasol wing but that is for a different debate.

So what does this have to do with the JF-17 ?

The point is that from the beginning, the wing designer, not the aircraft designer, already have a set of constraints. The JF-17 is a fighter, intended foremost to have high maneuverability before cargo capability. High wing designs have high lateral stability, which is good for high volume, heavy weight, and bulky cargo carrying capability. So the C-130, C-141, and C-5 took this approach.

Other factors that create many other sets of constraints are:

1- Horizontal to the fuselage, as in where is/are the wing(s) on or relative to the length of the fuselage.

2- Wing span, whether the aircraft will have a mono-wing like the cargo carriers or two wings like the fighters.

3- Sweep angle.

4- Cross section or airfoil, as in NACA standards.

5- Dihedral angle.

6- Root chord.

7- Tip chord.

8- Mean aerodynamic chord.

9- Aspect ratio.

10- Taper ratio.

11- Twist angle or washout and this affects lift distribution.

12- Flaps.

13- Ailerons.

14- Incidence angle.

For the JF-17, the 'high wing' design is eliminated and the 'mid wing' design chosen out of the need for maneuverability. Or to put it another way, the greater the need for maneuverability, the greater the need for a higher leading edge sweep angle, which prefers using the fuselage for greater structural strength to withstand the higher stresses created by aerobatics. The 'mid wing' design is also more conducive to the blended fuselage-wing structure.

Some wing designs have non-constant sweep angle: The Space Shuttle. This is not the same as variable sweep angle like on the F-14 and F-111. For the Space Shuttle, the wings' leading edges have two fixed sweep angles starting from the forward fuselage section towards the rear and they are fixed. The front sweep angle is 81 and turns to 45 going aft. Altering one sweep angle without considering the other and the result may be decreased stability performance during reentry or a higher glide landing speed. NASA probably archived those other combinations for future reference.

There is no 'best' wing, only the best combination of all of the above 14 factors once a wing type (high, mid, or low) is finally selected for a particular aircraft design. Even if a wing have no sweep angle, like that on a pure glider, a zero value for sweep angle is still a valid factor. Indiscriminate enlargement of the wing's surface area WITHOUT considering those fourteen factors above WILL produce unexpected and probably reduced performance at some flight regime, such as air density at different altitudes, or increased drag in a turn which will be deadly for the pilot, or possibly with enlarged wing surface area airflow may be too much for the aileron which results in lower roll performance, or there is an increase in pitching moment that cannot be compensated. For the wing designer, his job is to fine tune all those factors to make the aircraft as close to customer demand as possible, and that mean each final combination is a set of constraints unique to that aircraft to give it stability and controllability.

If the wing designer come to me with a proposal for a larger wing on an existing aircraft, my job as a process and sub-system integration specialist, a babysitter of sorts, is to make sure everybody's children can play nice with each other. I would set a meeting with the flight controls engineer, specifically the fligh control laws engineer if the aircraft is a fly-by-wire type FLCS, and ask him if the proposed larger wing can be accepted by the flight controls laws. He may say that the mean aerodynamic chord (MAC) is different, which create a higher roll rate that his roll rate gyro cannot monitor, which affects the pitch-roll integrator that enables smooth turns. Besides the flight controls engineering team, the structural integrity engineering team may say the larger wing area create more stress on the fuselage connection, which in order to support the larger wing they would have to install larger and more expensive support structures which increases overall weight.

Does this mean the JF-17 cannot have larger wings ? The JF-17 CAN have larger wings. The question is more financial than it is technical. Of course, the finance involved may be great enough that might as well Pakistan follow the F-18 path and create a larger JF-17.

Bottom line is this: AFTER the wing type is selected: high, mid, or low, those 14 factors direct the design of the wing in order to accomplish a mission. Changing any one of them demands precise and patient examination on the effects on the rest, which ultimately will change aircraft performance in some ways.

 

[Bilal.]

View attachment 157907

Conflicting figures? Which one is right?

 

[Najam Khan]

View attachment 157965

View attachment 157966

Looks like some procurement orders for next JF-17 squadrons.
GSE (Ground Support Equipment), GTE (Ground Testing Equipment), GHE (May be Hydraulics Equipment ).

 

[HRK]

Looks like some procurement orders for next JF-17 squadrons.
GSE (Ground Support Equipment), GTE (Ground Testing Equipment), GHE (May be Hydraulics Equipment ).

but directly jumping to 4th squadron where is the long awaited 3rd sqd ....??

 

[Tempest II]

`

Conflicting figures? Which one is right?

I posted this focusing on the weights, but on second look, the plane dimensions given are different.