JF-17 Thunder Multirole Fighter [Thread 6]

[Shabi1]

Hi,

I am looking at the JF 17 on its own merits----. If you look at my years old post---I had stated that this aircraft was not the aircraft that was needed for the hour---but that is what we got---.

It is not what this aircraft has and what it does not have---the most important thing amongst everything about this aircraft is----what is the loiter time---. If it is 45 minute---then it is a worthless aircraft-----regardless of what it has----.

Then those who designed this aircraft on our side and pushed for it---need to be tried for treason and hanged.

A loiter time figure of 45min is absurd and it is based on speculation from an article opinion who based it on test/demo flights. Not based on any official statement. Makes no sense since the ferry range is 3000-3482km (sources vary). The JF-17 will have to do a sustained supercruise at Mach 3.79 (4642km/h) to reach 3482km in 45min which is not possible. Supercruise on the F-22 is Mach 1.2.

So far from what I can gather the only poster with loiter time mentioned states it at 3.5hrs and found a source for 3hrs. So my guess is it should be taken as 3-3.5hrs

However the JF-17 should not be criticized for its spec, it is not supposed to be the most advanced jet in PAFs fleet. Its a multirole workhorse, and for that role it is the perfect aircraft, it can carry a wide range of advanced weapons and can stand its ground when it will need to defend itself. PAF does need an aircraft with higher performance specs (range/speed/endurance) for air superiority role regardless of same weapons or similar radars. Should come in the form of J-10B/C or J-31. Same as the F-16/F-15 Combo in US and Israel.

 

[alimobin memon]

if so then why 1 hr for jf17 just like egypt israel case what would happen if indian jets have 2 to 3 hr time ? i am bit confused here. How much time does it take for airforce fighters to conduct a mission and come back to base ?

Hi,

It is roughly 2 1/2 to 3 1/2 hours----. Loiter time is when you are flying with extra fuel tanks.

 

[Shabi1]

if so then why 1 hr for jf17 just like egypt israel case what would happen if indian jets have 2 to 3 hr time ? i am bit confused here. How much time does it take for airforce fighters to conduct a mission and come back to base ?

You need to have a decent loiter time to search for targets or engage in fights. No use engaging if you dont have fuel.

 

[ACE OF THE AIR]

You need to have a decent loiter time to search for targets or engage in fights. No use engaging if you dont have fuel.

Still PAF pilots flying Syrian Migs engaged IAF Mirages.

Syria 1974
During this war, Flt.Lt Sattar Alvi was decorated by the Syrian goverment when he shot down an Israeli Mirage over Golan Heights. On 26 April, 1974, in an encounter over Golan Heights between a Mig-21 of the Syrian Air Force, flown by Flight Lieutenant Sattar Alvi, PAF, and two Israeli Mirages.

 

[JamD]

A loiter time figure of 45min is absurd and it is based on speculation from an article opinion who based it on test/demo flights. Not based on any official statement. Makes no sense since the ferry range is 3000-3482km (sources vary). The JF-17 will have to do a sustained supercruise at Mach 3.79 (4642km/h) to reach 3482km in 45min which is not possible. Supercruise on the F-22 is Mach 1.2.

So far from what I can gather the only poster with loiter time mentioned states it at 3.5hrs and found a source for 3hrs. So my guess is it should be taken as 3-3.5hrs

However the JF-17 should not be criticized for its spec, it is not supposed to be the most advanced jet in PAFs fleet. Its a multirole workhorse, and for that role it is the perfect aircraft, it can carry a wide range of advanced weapons and can stand its ground when it will need to defend itself. PAF does need an aircraft with higher performance specs (range/speed/endurance) for air superiority role regardless of same weapons or similar radars. Should come in the form of J-10B/C or J-31. Same as the F-16/F-15 Combo in US and Israel.

Ferry range means WITH drop tanks and minimum equipment (ie no other weapons payload)

The basic range by your screenshot is given as 1800 km.

Assuming a cruise at Mach 0.7 @ 40,000 ft the speed translates to 743.4 km/h.

This means an endurance of 2.42 hours. But that seems rather large for basic range, but then again my calculations are with many simplifying assumptions.

EDIT:
Let me do better numbers using Breguet equations for loiter. Loiter and cruise are different, something which i have overlooked above.

EDIT2:
I'm getting an endurance of around 5 hours on internal fuel using an L/Dmax of 10, TSFC of 0.55 and assuming no fuel is burnt during warmup and takeoff. But then again the Breguet equation is mostly shit for this lol.

2.42 hours seems reasonable to me. Because at cruise the TSFC of the RD-93 is probably higher than 0.55lb/lbf-h. It's probably around 0.65.

 

[Shabi1]

Ferry range means WITH drop tanks and minimum equipment (ie no other weapons payload)

The basic range by your screenshot is given as 1800 km.

Assuming a cruise at Mach 0.7 @ 40,000 ft the speed translates to 743.4 km/h.

This means an endurance of 2.42 hours. But that seems rather large for basic range, but then again my calculations are with many simplifying assumptions.

EDIT:
Let me do better numbers using Breguet equations for loiter. Loiter and cruise are different, something which i have overlooked above.

Actual figures might be classified but one thing is for sure the 45min assumption is clearly wrong. ~2.5hrs + is actually pretty good.

 

[MastanKhan]

A loiter time figure of 45min is absurd and it is based on speculation from an article opinion who based it on test/demo flights. Not based on any official statement. Makes no sense since the ferry range is 3000-3482km (sources vary). The JF-17 will have to do a sustained supercruise at Mach 3.79 (4642km/h) to reach 3482km in 45min which is not possible. Supercruise on the F-22 is Mach 1.2.

So far from what I can gather the only poster with loiter time mentioned states it at 3.5hrs and found a source for 3hrs. So my guess is it should be taken as 3-3.5hrs

However the JF-17 should not be criticized for its spec, it is not supposed to be the most advanced jet in PAFs fleet. Its a multirole workhorse, and for that role it is the perfect aircraft, it can carry a wide range of advanced weapons and can stand its ground when it will need to defend itself. PAF does need an aircraft with higher performance specs (range/speed/endurance) for air superiority role regardless of same weapons or similar radars. Should come in the form of J-10B/C or J-31. Same as the F-16/F-15 Combo in US and Israel.

Hi,

You are correct----for an aircraft this size---if the loiter time with full load is 1 1/2 to 2 hours---that will be good enough----.

if so then why 1 hr for jf17 just like egypt israel case what would happen if indian jets have 2 to 3 hr time ? i am bit confused here. How much time does it take for airforce fighters to conduct a mission and come back to base ?

Hi,

It is not about conducting a strike mission---but for JF 17 how long can it be on air patrol---ie being on sentry duty---defending the skies. So---if it can maintain its position for over an 1 1/2---that is very good news---.

 

[SQ8]

Hi,

You are correct----for an aircraft this size---if the loiter time with full load is 1 1/2 to 2 hours---that will be good enough----.




Hi,

It is not about conducting a strike mission---but for JF 17 how long can it be on air patrol---ie being on sentry duty---defending the skies. So---if it can maintain its position for over an 1 1/2---that is very good news---.

Without AAR, the drop tanks are needed to keep it on station that long. However, as such many jets stick to external tanks to maintain CAPs

 

[ACE OF THE AIR]

Without AAR, the drop tanks are needed to keep it on station that long. However, as such many jets stick to external tanks to maintain CAPs

Sir, is it not normal practice to fly with drop-tanks always and then jettison them later in case of intercepting or bombing missions?

 

[SQ8]

Sir, is it not normal practice to fly with drop-tanks always and then jettison them later in case of intercepting or bombing missions?

Usually is, but for the JF-17 that means sacrificing payload. However, considering normal operational requirements it may be sufficient

 

[Basel]

Sir, is it not normal practice to fly with drop-tanks always and then jettison them later in case of intercepting or bombing missions?

Here CFTs comes into play. JF

 

[Wolfhound]

Here CFTs comes into play. JF

CTFs were needed from the start for jf17 and should be in consideration for block 3

 

[ACE OF THE AIR]

Here CFTs comes into play. JF

Bro that is still going to take toll on Payload till a high power engine or serious weight reduction is not done by using composites.

CTFs were needed from the start for jf17 and should be in consideration for block 3

One can not design a new aircraft with CFT's. If one requires more range then the Wing design can be altered to a delta configuration or a trim tank in the tail can also be considered.

 

[ConcealCarry]

It's a vicious cycle, add more internal fuel, that increases weight and thus consumes more fuel and reduces speed, to counter that add a bigger/powerful engine, that consumes more fuel thus reduces range/loiter time. External fuel tanks are best, they add temporary capacity and weight, consume first and jettisoned when required. What thunder needs is two additional underbelly hard points, or slight extension of wings to make room for AAM between station 1&2 and 6&7

Bro that is still going to take toll on Payload till a high power engine or serious weight reduction is not done by using composites.


One can not design a new aircraft with CFT's. If one requires more range then the Wing design can be altered to a delta configuration or a trim tank in the tail can also be considered.

 

[salman-1]

Fuel is heart and soul of every mission assigned to a Jet Fighter.
Engine runs on fuel and Fighters runs on Engine..
Below is Internal fuel capacity of 4th ~ 5th Gen fighters
Su-35BM: 39.6% ~ 41.1%（Empty weight: 16,500 ~ 17,500 kg，Internal fuel: 11,500 kg）

MIG-31: 39.4%（Empty weight: 21,825 kg，Internal fuel: 14,200 kg）

F-35A: 38.9%（Empty weight: 13,170 kg，Internal fuel: 8,382 kg）

F-35C: 38.5%（Empty weight: 14,548 kg，Internal fuel: 9,111 kg）

Su-30MK: 34.9%（Empty weight: 17,700 kg，Internal fuel: 9,500 kg）

Rafale: 31.4% ~ 33.6%（Empty weight: 9,500 ~ 10,220 kg，Internal fuel: 4,680 ~ 4,800 kg）

F-18E: 32.2%（Empty weight: 14,288 kg，Internal fuel: 6,780 kg）

EF-2K: 30.9%（Empty weight: 11,150 kg，Internal fuel: 4,996 kg）

JAS-39NG: 30.6%（Empty weight: 7,100 kg，Internal fuel: 3,130 kg）

F-35B: 30.3%（Empty weight: 14,588 kg，Internal fuel: 6,352 kg）

F-22A: 29.3%（Empty weight: 19,660 kg，Internal fuel: 8,165 kg）

MIG-35: 28.6%（Empty weight: 12,000 kg，Internal fuel: 4,800 kg）

Tejas: 27.0%（Empty weight: 6,500 kg，Internal fuel: 2,400 kg）

JF-17: 26.3%（Empty weight: 6,450 kg，Internal fuel: 2,300 kg）

JAS-39C: 25.0%（Empty weight: 6,800 kg，Internal fuel: 2,268 kg）

F-CK-1A: 24.5%（Empty weight: 6,492 kg，Internal fuel: 2,111 kg)

JFT uses RD-93 a varient of RD-33
SFC SFC
(dry) (dry)
[lb/lbf hr] [lb/lbf hr]
0.740 2.050



Many issues come to my mind when looking at the naked OEW and internal fuel numbers.

1. The OEW figures are normally wrong, the Sukhois are heavier, the "official" numbers often exclude some items. Cheating on OEW is due practice everywhere around the world.
2. As was stated before, fuel carried is one thing. Fuel consumed is another. The fuel consumption depends on:
   • basic air frame drag (which is largely the same for all 4th generation aircraft)
   • normal mission layout, a fighter carries significantly less load than a bomber
   • requirements on operational safety (aircraft carrier)
3. As I said repeatedly, more internal fuel is not always better. An air combat fighter is designed to have lowest when entering combat. The F-16 was designed with requiring 9g performance at 50% internal fuel. A closer look at the numbers unveils that such low internal fuel would basically cut the burner time to one minute, assuming the pilot wants to eat dinner at his base instead of having a C-ration in the woods.
4. Internal weapons cut the drag, while that doesn't change the overall picture too much when looking at cruise ranges. The drag of externally carried missiles below ~M.85 is acceptable. Everything counts in large amounts though: look at a Sukhoi 27 with full missile armament
   http://commons.wikimedia.org/wiki/Fi...7_armament.jpg ... sukhoi is draggy
5. A clean aircraft at 30k ft and ~M.8 (optimum range Mach) will see the engine operating close to idle, especially aircraft with a clear supersonic ability. The SFC (specific fuel consumption) jumps up significantly. Carrying external tanks causes more drag, but the effect of operating in a more efficient engine regime compensates that to some extent. Generally the penalty in subsonic (up to M~.85) drag for drop tanks is quite low, about 10% of zero lift drag for a 300gal drop tank.
6. The fuel burn also depends on type of engine (though quite similar for all considered aircraft) and altitude/speed profile. Though an F-18 might fly for 2 hours on internal fuel and cover over 1500km of distance, going into burner for a minute easily eats up 15 minutes normal flying time.
7. When you wanna see the specifications of a true fighter, look up YF-16. Nothing ever came close, the Euro fighter maybe.