This is not so difficult to answer. There are many ways to answer this question. You know that the ferry range is 1700 kms with 1200 ltr drop tanks. So it must at least have a 2 hour endurance under cruise condition.
Another way is to calculate it is from the SFC. But you would need to know the thrust required for the flight at the aforementioned range. I don't know that. But let us continue. For example, let us find the endurance at maximum speed without afterburner. We know that:
1. SFC for military thrust = approx. 84 (kg/kN-hr) .
2. Maximum military thrust = approx. 54 kN.
3. Therefore, the rate of fuel consumption at this speed = approx. 54 kN * 84 kg/(KN-hr) = approx. 4536 kg/hr.
4. Total fuel: 2 X 1200 ltr tanks and about 2600 kg of internal fuel = approx. 4600 kg
5. Therefore, endurance in this regime is nearly 1 hour, and you would have flown around 800-900 kms.
You can do the same thing with afterburners. It will be about half an hour (but you will most probably cook the engine before that).
I want to know why you find endurance important? You can fly slower, hang in there longer and travel lesser. What would be the point?
SO for a combat sortie with 1300 Km combat radius stretching over two hours fifteen minutes Gripen NG would need more than 9 tons of fuel (that too only in case it was flown below super sonic speeds(not possible considering its max endurance)) .
GE-414 is a bit better at SFC. But looking at it any way things don't tally here!!!!!!!!
The su-24 is advertised as
Operational radius of action at sea level in mixed mode (Vcr in the 200-km area, V=900 km/h in other areas) with PTB external fuel tanks and 6x FAB -500M-62 bombs, 615 km.
Whose specs are
Crew: Two (pilot and weapons system operator)
Length: 22.53 m (73 ft 11 in)
Wingspan: 17.64 m extended, 10.37 m maximum sweep (57 ft 10 in / 34 ft 0 in)
Height: 6.19 m (20 ft 4 in)
Wing area: 55.2 m² (594 ft²)
Empty weight: 22,300 kg (49,165 lb)
Loaded weight: 38,040 kg (83,865 lb)
Max. takeoff weight: 43,755 kg (96,505 lb)
Powerplant: 2 × Saturn/Lyulka AL-21F-3A turbojets
Dry thrust: 75 kN (16,860 lbf) each
Thrust with afterburner: 109.8 kN (24,675 lbf) each
Fuel capacity: 11,100 kg (24,470 lb)
Performance
Maximum speed: 1,315 km/h (710 kn, 815 mph, Mach 1.08) at sea level; Mach 1.35 (1,654 km/h) at high altitude
Combat radius: 615 km in a low-flying (lo-lo-lo) attack mission with 3,000 kg (6,615 lb) ordnance and external tanks ()
Ferry range: 2,775 km (1,500 nm, 1,725 mi)
Service ceiling: 11,000 m (36,090 ft)
Rate of climb: 150 m/s (29,530 ft/min)
Wing loading: 651 kg/m² (133 lb/ft²)
Additionally, I should mention that a similar first order analysis for the LCA yields a range (one-way) of ~1550 km (give or take) assuming only internal fuel of (2500 kg) at 10,000 feet at Mach 0.6 (measured at sea level). This Mach 0.6 requirement in cruise stems from the need to carry only internal fuel and empty weight of the aircraft, i.e. no external fuel tanks.
So for the above flight profile setup, the combat radius comes out to ~700 km.
But this carries no payload and or fuel tanks. Fuel tanks will increase range. Payload and external tanks will increase drag and reduce range. I will try and put up some numbers for that later when I get some time to model the tanks underneath the wings (been wanting to do that for some time but this argument about the LCA range has finally sent me over the deep end 8) ).
Edit: So the addition of two external drop tanks provides an increment of about 33% in drag at the benefit of additional ~1900 kg of fuel. This amounts to about ~2000 km ferry range. Assuming that there is significant burnoff of fuel during climb and recovery, the 1700 km ferry range quoted by the document listed above makes sense.
Additionally, I should mention that a similar first order analysis for the LCA yields a range (one-way) of ~1550 km (give or take) assuming only internal fuel of (2500 kg) at 10,000 feet at Mach 0.6 (measured at sea level). This Mach 0.6 requirement in cruise stems from the need to carry only internal fuel and empty weight of the aircraft, i.e. no external fuel tanks.
So for the above flight profile setup, the combat radius comes out to ~700 km.
But this carries no payload and or fuel tanks. Fuel tanks will increase range. Payload and external tanks will increase drag and reduce range. I will try and put up some numbers for that later when I get some time to model the tanks underneath the wings (been wanting to do that for some time but this argument about the LCA range has finally sent me over the deep end 8) ).
Edit: So the addition of two external drop tanks provides an increment of about 33% in drag at the benefit of additional ~1900 kg of fuel. This amounts to about ~2000 km ferry range. Assuming that there is significant burnoff of fuel during climb and recovery, the 1700 km ferry range quoted by the document listed above makes sense.
Bottom line is that you determine what the flight characteristics needs to be to lift X kg of mass of the aircraft at a certain altitude and corresponding atmospheric conditions. If you know the CL-AOA behavior of the wing, the minimum required Mach number in cruise is determined. For the present case, at 10,000 feet AGL, the required Mach number for cruise without payload or tanks comes out to Mach 0.6. This is then used to evaluate the net drag on the fuselage. Again, modeling the induced-drag profile of the mean-camber wing plus a Reynolds number based skin-friction drag model gives you representative CDi and CDo values. The sum of these parameters (plus correction factors for additional drag from fuselage and empennages) gives you a net cruise drag coefficient. Multiply this by the dynamic pressure using the Mach 0.6 conditions and you will get the net required thrust to maintain this constant speed.
For the present case, the required thrust came out to ~0.29 Kg/sec for the LCA, which is below what you get assuming full thrust from engine (~1.232 Kg/sec). The reason for this is that the entire engine thrust is not needed for balancing drag at higher altitudes and moderate speeds. Same reason why all aircraft perform better the higher they climb for the cruise part of their flight.
Knowing the fuel consumption and the cruise Mach number (measured relative to Sea-Level atmospheric conditions) provides you with the ability to calculate how far the aircraft can go if it went in a straight line.
For the LCA, this came out to be ~1550 km as stated previously.
Note that this is all a first order analysis, of course, and only meant to be a sanity check on performance. I used to teach such relatively simple (back of the envelope) methods to students as a way to bypass the complexity of full-up computational methods when quick analysis is required.
Add about 30% on drag increment for the external payload on this one (~8% each for one large bomb plus pylon effects). The range is then reduced to around ~1190 km. Combat radius is reduced to around ~500 km or less.
The Beta Coefficient...: Search results for lca
Some interesting statements on combat range of tejas in different profiles, presented by Vivek Ahuja
Low altitude air space penetration flight profile (4x 250 kg bombs, fuel max internal and all available external)combat radius of 700 Km,
high altitude PGM attack profile (2 LGBs , all available external and internal fuel)- a combat radius of 1200 Km,
HAL gives a radius of action up to 500 Km for tejas, but does not specifies the fuel or weapon combo along with flight altitude,
Mirage-2000 has a fuel fraction of around 30 percent similar to tejas,
So I think there won't be any significant difference combat range between the two fighters if similar altitude and roles are assigned with optimum load capacity for each fighter,
we need to know what is the combat range of jags in indian hot arid climatic conditions. that is the key. Simply wiki figures are not enough.
needs some clarification as well,
but for what i was asking for when in a lightly loaded CAP mission a fighter could only endure 2.15 hours , how the hell it is going to last 1300 Km comabt radius(2x1300 Km is 2600 Km ) in a combat sorties and with what endurance , what speed and what fuel burn rate and with how much fuel requirements?
if you have any relevant calculations please post, thanks,
What is the amount of fuel needed for this combat mission , whether it was in lo-lo mode or hi-lo-hi mode and with what weapon config.
But no body is asking for
educated guess around here, what I meant was how long would gripen take to complete its ferry range of 4000 Km. that is the essence of my post.
First understand in which context a questionis raised before name calling, I was not name calling any one in my post, got it?
SO ANSWER HOW MUCH TIME WILL IT TAKE FOR GRIPEN NG TO COMPLETE ITS 4000 Km ferry range(If max endurance in lightly loaded combat air patrol is just 2hours fifteen minutes)
And what is the particular reason that makes you hot under collar whenever I make a comparison of gripen range with tejas? I was not pronouncing any judgements here, just asking guys to reconcile the calculations in the two links they themselves gave. thats all.
The reason I wanted to raise it was it was publicly mentioned that that Rafale took 10 hours for 1000 Km reunion island sortie with just two external fuel tanks and five inflight refuellings.
So rafale can fly 2+ hours with a single refuel ..and It takes nearly 11 hours to reach Reunion Island. distance from French mainland to
Reunion Island is about 5,717 miles or 9200 KM ..so nearly 900 KM per Hour or 560 mile Per Hour ..interesting
there were 2 Two Seater Rafale carrying two Fuel tanks looks like 1200liters Tank enroute to reunion islands
a two seater rafale along with two 1200 liter tank can fly more than 2 hours can go 900km up/down ..So it's well we can see Rafale in SEAD config can engage target upto 400KM inside enemy territory with out Drop tanks ..
two drop tanks with a Full combat load it can go around 500 KM inside hostile Territory can Destroy enemy Infrastructure
with decent A2A load along with two or three Drop tanks can stay in the air for more than 2 hours can act as a Good CAP platform.
Can we assume that its practical non refuelled radius of action with normal combat weapon load is about 900 Km?
