JFT Supercruise capability ?

[Kompromat]

Possibility of Supercruise for JFT with a 100KTN WS-13 Engine in A2A Role ?

Introduction:

What is Supercruise ?

Supercruise is sustained supersonic flight of an aircraft with a useful cargo, passenger, or weapons load performed efficiently and without the use of afterburners ("reheat").

First Fighter jet ever to Supercruise

English Electric Lightning.

Benefits of supercruise.

The term supercruise was originally used to describe a fighter performance requirement set forth by USAF Col. John Boyd, Pierre Sprey, and Col. Everest Riccioni, designers of the F-16 Falcon. Following the entry into production of the F-16, they began work on an improved fighter design with the ability to cruise supersonically over enemy territory for a minimum of twenty minutes.

As air combat is often the result of surprise, and the speed of the combat is determined by the speed of the surprising aircraft, this would have given a supercruise-capable design a worthwhile performance advantage in many situations. The postulated fighter would have had a top speed of just over Mach 1, and a fuel fraction in excess of 40%, the minimum required to successfully meet the twenty-minute requirement.

Meeting the fuel fraction requirement necessitated a very austere design with few advanced electronics. The United States Air Force showed no interest in the proposal at that time, but years later revived the term and redefined it to apply to the requirements for the Advanced Tactical Fighter, which resulted in the F-22 Raptor

Air Crafts capable of Supercruise

1: F-22A Raptor USAF (PW-F-119 Engine)
2: EF-2000 Typhoon (EJ-200 Engine)
3: JAS-39 Gripen NG (GE F-414 Engine)
4: JSF
5: Lockheed Blackbird (A-12, YF-12 and SR-71)
6: Tupolev Tu-128
7: Tupolev Tu-144
8: Dassault Rafale
9: Sukhoi Su-35BM
10:Sukhoi PAF-FA

Analysis

The most Relevant example in this matter for JFT is JAS-39 Gripen NG in terms of design , weight and Engine thrust.

JAS Configuration

The new Gripen NG (Next Generation) will have many new parts and will be powered by the General Electric F414G, a development of the F/A-18E/F Super Hornet's engine.

The engine will produce 20% more thrust at 98 kN (22,000 lbf), enabling a supercruise speed of Mach 1.1 with air-to-air missiles

Compared to the Gripen D, the Gripen NG's max takeoff weight has increased from 14,000 to 16,000 kg (30,900–35,300 lb) with an increase in empty weight of 200 kg (440 lb)

Empty weight: 5,700 kg (12,600 lb) + 200kg = 5900 KG
Loaded weight: 8,500 kg (18,700 lb)
Max takeoff weight: 14,000 kg (31,000 lb)
Powerplant: 1× Volvo Aero RM12 afterburning turbofan
Dry thrust: 54 kN (12,100 lbf)
Thrust with afterburner: 80.5 kN (18,100 lbf)
* F-414 Thurst with AB = 98.0 KTN
Thrust/weight: 0.97

JFT Current Configuration

Empty weight: 6,411 kg (14,134 lb)
Loaded weight: 9,100 kg including 2× wing-tip mounted air-to-air missiles (20,062 lb)
Max takeoff weight: 12,700 kg (28,000 lb)
Powerplant: 1× Klimov RD-93 turbofan
Dry thrust: 49.4 kN (11,106 lbf)
Thrust with afterburner: 84.4 kN (18,973 lbf)
Thrust/weight: 0.99

WS-13

Development started in 2000; based largely on RD-33/93 but with substantial new inputs 2,200 hour life span , reports of 100kN/22,450lbs thrust version in development

My opinion

I think that in order to get JFT to supercruise at mach 1.1 with A2A configuration we need to reduce the weight of the aircraft by using Composite materials and when fitted with a 100KTN Engine (Which is more powerful than F-414) i dont have any reason to believe that the JFT wont be able to do supercruise.

A powerful engine and reduced overall weight of the airframe would also Enable JFT to cross Mach-2.0 top speed and would give it great acceleration considering its design and Divertless supersonic intakes it makes sense to me.

Please share your opinion ??

Regards: Black Blood

 

[sparklingway]

Super-cruise seems way out of the league for JF-17. Way, way out of the league as this is no interceptor nor is it a stealth fighter and never meant to be one. Super-cruise is an expensive solution, besides it will require extensive, perhaps a total re-design of the plane. It's not just a powerful engine with 1-2-superfast option it will require a structure that can withstand the forces. I'm no expert, or even remotely well read in aerodynamics but my gut feeling is certainly of extreme skepticism.

 

[Kompromat]

Super-cruise seems way out of the league for JF-17. Way, way out of the league as this is no interceptor nor is it a stealth fighter and never meant to be one. Super-cruise is an expensive solution, besides it will require extensive, perhaps a total re-design of the plane. It's not just a powerful engine with 1-2-superfast option it will require a structure that can withstand the forces. I'm no expert, or even remotely well read in aerodynamics but my gut feeling is certainly of extreme skepticism.

Supercruise has got nothing to do with 5th generation , stealth and has got little to do with the price tag as you EE Lightning was the first Jet to do supercruise.

Its about Design which luckily we have a refined aerodynamic structural design in shape of JFT , one Little example is that by just Installing Divetless supersonic intakes the top speed was increased from Mach 1.6 to mach 1.8 with the same amount of thrust

I would consider JFT's design even more suitable for supercruise just because of DSI and modular fuselage that has some good potential for changes in coming years.

All we need to supercruise our jet is:

WS-13 Engine with 100Ktn thurst and reduce its total weight by using composite materials.

*When i say supercruise i mean in A2A role only.

 

[Jigs]

I agree i don't see it being able to Supercruise. The things to achieve with the JF-17 are better avionics and a greater Thrust-to-weight ratio. Anything beyond that will not occur. It was never meant to be a high end performance machine. A low cost lightweight 4th gen fighter was the goal here. PAF has the Block 52s for a more advanced platform.

 

[Kompromat]

I agree i don't see it being able to Supercruise. The things to achieve with the JF-17 are better avionics and a greater Thrust-to-weight ratio. Anything beyond that will not occur. It was never meant to be a high end performance machine. A low cost lightweight 4th gen fighter was the goal here. PAF has the Block 52s for a more advanced platform.

You are right in your say but look at this :

JFT has completed taxi runs with WS-13 Engine which also has a variant with 100KTN thurst which almost is 12% more than current RD-93's thrust and more than the Engine used on Gripen NG the F-414 which has a thrust of 98KTN.

Gripen a fighter similar to JFT in terms of Thrust to weight ratio , Empty and loaded weight , aerodynamics and now propulsion is doing supercruise. The only significant difference is that Thunder is almost 300kg heavier than Gripen which can easily be reduced by using composite materials.

We are going to Install WS-13 anyway and this thread is to judge if the Upcoming Block of JFT can be modified in a way while in limited budget to be able to do supercruise in A2A configuration only !

I know its a low cost fighter and is not close to F-16 but lets not forget F-16 is a much different design.

* Gripen didn't supercruise with RM-12 Engine Just because of low power and acceleration

In my opinion PAC and CATIC should work on this aspect in upcoming blocks as it wont be any expensive neither we would have to build the A/C from the scratch and it will give yet another advantage over enemy aircrafts.

What do you say ?

 

[Jigs]

You are right in your say but look at this :

JFT has completed taxi runs with WS-13 Engine which also has a variant with 100KTN thurst which almost is 12% more than current RD-93's thrust and more than F-414 which has a thrust of 98KTN.

Gripen a fighter similar to JFT in terms of Thrust to weight ratio , Empty and loaded weight , aerodynamics and now propulsion is doing supercruise. The only significant difference is that Thunder is almost 300kg more heavier which can easily be reduced by using composite materials.

We are going to Install WS-13 anyway and this thread is to judge if the Upcoming Block of JFT can be modified in a way while in limited budget to be able to do supercruise in A2A configuration only !

I know its a low cost fighter and is not close to F-16 but lets not forget F-16 is a much different design.

In my opinion PAC and CATIC shour work on this aspect in upcoming blocks as it wont be any expensive but it will give yet another advantage over enemy aircrafts.

What do you say ?

300kg + the A2A loadout+more drag

If they can overcome these things they should go for it but i don't see the engineers working on trying to make it supercruise. I am not saying it is impossible our 2020 terminators lost 750kg just from hydraulic and wiring changes. That is a fighter/bomber though.

 

[dbc]

All MACH capable aircraft's can be made to supercruise under the right conditions but how long can it be sustained? The real secret to supercruise is thrust minus drag.

The best seat in the house for supercruise is from a chase F-16 or F-15. Remember, we fly both these chase jets with just a centerline fuel tank to give them a fighting chance to play with the Raptor. Still, the F-22 usually leaves these aerodynamically “slick” chase airplanes in the dust. The F100-110, -129, and -229-powered F-16s don’t fall very far behind the Raptor in the initial acceleration through Mach. But the race is really no contest at the higher Mach numbers and once on cruise conditions. Nothing can sustain supersonic conditions with the persistence of a Raptor. Load those chase F-16s and F-15s with combat-representative stores and they would not stay with the Raptor during acceleration or sustained cruise.

Sparklingway is right the JF-17 will need significant redesign to reduce drag in supersonic flight to sustain supercruise.

 

[ptldM3]

There are many factors involved in supercruising, obviously the T/W ratio is important but equaly as important is the construction of the aircraft.

I think i talked about this before but i will say it again, the design of the airframe is as important as shear trust. Both the Mirage and the F-104 acheived incredible speeds and both had weak powerplants. The F-104 acheived its speed because of its thin trapezoid wing, the Mirage acheived its speed because of its swept wing design.

Lets look at the advantages of the swept wing design:

Lockheed F-104 Starfighter - Wikipedia, the free encyclopedia

Swept wings are used on aircraft not only to increase stability and the pilots view, but they also allow the plane to fly at much higher speeds. By placing the wings at an angle of 30 or 40 degrees, the critical Mach number can be increased, decreasing the drag and delaying or preventing shock stall. Shock stall is caused by the center of pressure moving backwards, interferes with the boundary layer and causes the plane to vibrate.

Sweeping the wings back also mimics a thin wing design similar to that of the F-104.

Untitled Document

Sweeping the wing to the rear makes it appear thinner and longer in the direction of the airflow

So we know that the delta wing is superior for high mach performance and we know the Electric Lightning performed supercruise with a weak powerplant , but where does that leave the JF-17? The JF-17's isn't a delta wing and it isn't an interceptor. Simlilarly it doesn't have the greates T/W ratio; however, with a more powerful powerplant and perhaps a reduction in weight this will change--obviously, but it still lacks the wing sweep that many aircraft utilize to acheive their performance, but other aircraft have also acheived supercruise without a swept wing design.

It's highly likely that a JF-17 can acheive supercruise if is gets a new powerplant coupled with weight reduction. However, i doubt it will be able to acheive supercruise with a full combat load, of course i could be wrong but i still have doubts, now if the JF-17 had its wings swept back further than there would be little doubt about supercruise.

So it really comes down to how much drag the aircraft creates.

Lets look at drag or more specifically wave drag, 'the Haack body' is most effective in countering the phenomenon of wave drag, a delt-wing would best represent the Haack body, some aircraft that are able to acheive a realatively fast cruise speed work on the principle of the Haack body, thus wave drag is significantly reduced.


http://rds.yahoo.com/_ylt=A0oGk0cni...n.wikipedia.org/wiki/Sears%E2%80%93Haack_body

The Haack body is, generally speaking, the body least susceptible to wave drag. By Frenzl's Area Rule, the derivative of cross-sectional area gives wave drag. Thus, the Haack body is pointed at two ends and grows to a maximum and then decreases toward the second point.

Under the area rule, shapes with the same cross-sectional area at each point along their length as this shape have the minimal amount of wave drag, and the overall shape of many aircraft designed with transonic flight considerations have cross-sectional areas that approach this form (despite appearances).

 

[Jigs]

The Starfighter was a rocketship It couldn't maneuver worth crap though because of the small wing area. Sustained turn performance was horrible. Man could it go though...and climb.

 

[Kompromat]

@ Russki:

I have mentioned above that i am just talking about A2A payload only & not with PGM's and LGB's.

You are right about what you have said but if the structural changes has to come in the upcoming blocks what a wonder would it be if the Engineers can utilize this opportunity of having a more powerful powerplant !

 

[Dazzler]

Well to be honest I never heard anything regarding super-cruise as an option on thunder but theoretically it can be achieved. What it does need is a better engine providing at least 1:1 ratio and more percentage of composite material for weight reduction than what it is using now. DSI advantage is certainly there as it will provide enough breathing to the engine. Many factors are involved even in a baseline (should i say limited) super-cruise such as the airframe strength, t/w ratio, payload, altitude etc. Even current super-cruise capable planes have different stats at different altitudes so many things to take care of.

 

[ptldM3]

@ Russki:

I have mentioned above that i am just talking about A2A payload only & not with PGM's and LGB's.

You are right about what you have said but if the structural changes has to come in the upcoming blocks what a wonder would it be if the Engineers can utilize this opportunity of having a more powerful powerplant !

When i spoke about the JF-17's potential to supercruise i put a strong ephasis on the airframe design and drag. What we have in the JF-17 is a wing sweep of 42 degrees. Similarly, the SU-35 has a wing sweep of 42 and it can supercruise. The problem is there can be other factors involved such as engine officiency, we know the JF-17 has divertless intakes but how officient are they compared to other aircraft?

Oh i almost forgot, the JF-17 has a low aspect radio (wing length) which is important for high speed flight, again this is another reason the F-104 had extreemly short wings.

 

[VCheng]

...........
All we need to supercruise our jet is:

WS-13 Engine with 100Ktn thurst and reduce its total weight by using composite materials.

.................

There is MUCH more to supercruise than just the T:W ratio, particularly careful airflow management by exacting design across all of the airframe.

 

[regular]

I guess it won't be easy to make JF-17 to supercruise with this engine unless we get new very powerful engine.....

 

[RazorMC]

We could place an extremely powerful engine in the Thunder but it still won't supercruise.
It will probably spin out of control, damage its airframe or even break apart completely.

Structural integrity is where lightweight fighters like the Thunder face problems.