Many fighter makers claim fancy ranges for their fighters in ideal cold climate conditions in high altitude.
gripen's makers say their fighter has a ferry and combat range closer to that of Su-30 MKI!!!
And many fancy 9 tons weapon carrying capacity to 3600 Km is claimed for rafale.
but the point to note is how much these fighters can fly in deep low level altitude penetration mode in indian sub continent where engine thrust and wing lift falls by close to ten percent due to hot conditions?
Effective combat range with effective weapon load will depend upon the criteria called fuel fraction, i.e weight of internal fuel/empty operational weight of the fighter.
In this area even tejas mk1 better than gripen C.
Then a question arises why range of tejas was often quoted less, it may be due to the reason that new super sonic center line fuel tank was not validated till IOC-2, Even without that The press information beruau release clearly stated that the combat radius of tejas is 500 Km. It means a combat range in excess of 1000 Km in a low penetration fuel consuming flight into enemy territory, with extra fuel allocation for take off, a few minutes of high fuel consuming close combat and high fuel consuming After burner thrust .
But other fighter makers give misleading combat range figures with minimum weapon config and high altitude(less fuel consuming flight path) with no allocation for close combat and AB thrust and low penetration mode.
Roughly the fuel fraction above will give us effective combat utilization of the fighter.
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）
JAS-39NG: 30.6%（Empty weight: 7,100 kg，Internal fuel: 3,130 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）
This is a fair comparison of fuel fractions with just internal fuel , and the same percentage will more or less reflect with external fuels also,
So Tejas mk-1(which still has 400 KG of flight test equipment on board, removal of them will lead to even better fuel fraction) itself has much better fuel fractions than grippen C/D with more TW ratio and lower wing loading,
Tejas mk-2 will easily compare to RAFALE which has just 4 percent more in fuel fractions than Tejas mk-1.
The important thing to note is that gripen Ng and rafale almost has the same internal fuel fraction and are claiming identical ranges whether in ferry or combat range!!!
tejas mk1 is above gripen C in internl fuel fraction. By the same token tejas mk2 will be at par with gripen NG in internal fuel fraction and almost at par with rafale also.
Also a recent report in janes claims that gripen NG with huge external fuel tanks,can fly 1300 Km with 6 air to air missiles and loiter for 20 minutes extra.
Considering tejas mk1 PIB claim of combat range in excess of 1000 Km for tejas depending upon the load even in tejas mk1 config the difference should not be that great.
Even in the worst case the difference should not be more than 5 percent!!!
So how can airmarshal barbora claim that rafle has thrice the range of tejas ?
So in indian conditions there won't be any great issues with range of tejas mk-2 in useful combat configuration if we take into account that four tejas can be operated for one RAFALE if we include total lifecycle costs and upgrade costs,
N one has replied till date, why two french rafales with two external fuel tanks each and no weapons ,
needed 5 refuelling for their 10.5 hour long 10000 Km trip from france to reunion islands?
Sure they must have had their tanks full at take off.
So it amounts to a total of 6 fuel loads for a 10000 Km flight with no weapon loads and only two external fuel tanks,
range comes only to 1500 Km around.
In an impressive demonstration of its strategic reach, two Rafales – supported by a C-135 FR air refueller – flew on a very long-distance practice exercise to the French island, Reunion, in the southern Indian Ocean. The Rafales' non-stop flight, which took 10 hours and 35 minutes and involved five inflight refuellings, was directed by the French Strategic Air Forces (FAS) Command.
Taking off on 22nd April 2014 at 5.00 am from Istres, the Rafale Bs arrived the same afternoon in Saint-Denis, the administrative capital of Reunion Island in the Indian Ocean. The very next day, they participated in a joint-services Close Air Support (CAS) exercise with the 2nd Marine Infantry Parachute Regiment stationed in La Réunion.
This mission formed part of regular exercises conducted by the FAS aimed at maintaining the proficiency of its crews in executing very long-range missions. It also demonstrated the ability of the FAS to intervene in any location whatsoever.
Is that anything to do with tropical hot tepmeratures or what?
I am asking this question for the third time. if people think karnard was tutored by me, why don't they tutor us on these little nuggets?
The press information bureau report of tejas IOC-2 also says that tejas can fly to distances 1700 Km non stop. (It does not mentions whether it is with combat load or on internal fuel only or external load ). But by the time of IOC-2 , tejas mk1(with much lesser internal fuel load than mk2) had only validated two exteranl fuel tanks.
The following is a reply for my query,
Huh? I don't think you understand what that means.
Efficiency is the key here. They don't fill the tanks up to the brim during such ferry range flights where fuel is preserved to the maximum. Fuel is managed so it provides the best performance figures possible.
They did not fill all of the aircraft up and then empty the tank before refueling again. They would keep around, say, 75%, use up enough fuel up to 50 or 40% and then refuel again to get it back to 75% and repeat the process 4 more times.
In actual missions, the refueling process would be different depending on the missions.
Naturally, in DPS missions the range is much smaller, said to be 3600 Km in a hi-lo-hi profile.
whatever the optimum flying conditions if you add weapons worth their price, and do a lo lo penetration with reservation for Ab thrusts and close combat and take off needs, the result will be the same
Even if we believe such no source fairy tales the, 3600 Km hi-lo-hi missions exist in libiya and mali where open skies with no enemy air defence spreads for a vast expanse of 1000s of Km.
The trouble with above explanation is,
When a tanker and two rafales take off from France, they will have x tons of fuels. So even if we accept that rafales were filled partially with fuel as fuel saving technique, it really is not going to save any fuel, because the x tons of fuels sits in the tanks of tanker aircraft and two rafales. SO the fuel saved on rafale by partial fuel filling will be expended by the jet engines of taker in carrying the total fuel in the air,
Considering that rafale are doing close to thousand Km per hour it is suboptimal for a tanker to fly at the cruise speed of rafale with excess fuel in its tank, rather than filling them in rafale's tanks,
It is always nice for the rafales to have the fuel in their tanks, because in case of any emergency on tanker rafales will be in a dicey position. Also in flight refuelling is a dicey affair too with its own excess fuel burn issues, SO it is much better to fill the fuel in all rafale tanks in one go rather than partially,
Another jarring issue is if rafales are to be filled only with partial fuel , then why two external tanks(which induce drag and reduce fuel efficiency!!!) present on rafale. They could have taken off without any external fuel tanks or at least one center line fuel tank for less fuel burning flight!!!
So most probably the 1500 Km range is due to the location of the reunion islands in the tropics with high temp(conditions like india) which saps close to ten percent of engine thrust and 12 percent of wing lift. Any other explanation looks suspect. Or we need some official clarification from IAF which tested rafales in hot condition.
And
rafale has just 4.7 tons of internal fuel. Even if we assume that the two external tanks each had a total of 3 tons fuel capacity,
considering the rafales M-88 has the same SFC as that of GE-404 in tejas mk1
In the same config tejas mk1 will have close to 4.5 ton external and internal l fuel with just one GE-404 burning with load of just 10 tons weight to support as total aircraft weight.
It will improve a bit in tejas mk2.
For the same config in rafale,
two M-88s in rafale will be burning 8 tons of total fuel with load of 17 tons to support.
So how come rafale will have thre times tejas range as barbora said?
But on india -pak borders and india-china borders enemy air defence is just a couple of hundreds of KM away.
SO practically those much vaunted 3600 Km range flaunted by forum trolls has no relevance to two front wars or in Tibet deep strikes.
Reality is sobering. As I said before in lo-lo penetration flight the differnece between tejas and rafale combat range will hug a figure closer to their difference fuel fraction ratio.
Dangling more and more external tanks and stuff will add to immense drag in lo-lo strikes . So the Rafale has thrice the range of tejas like statements made by people is just irrelevant in indian air space where enemy air defences are just next door.
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So in indian conditions there won't be no issues with range of tejas mk-1 or mk-2 in useful combat configuration if we take into account that four tejas can be operated for one RAFALE if we include total lifecycle costs and upgrade costs,
So there is no way Tejas can be faulted on weapon load or range. A full read of the link above will show how fighter makers abroad indulge in word play when it comes to range and load figures!!! , to fool the people.
Also indian hot atmospheric conditions sap close to 10 percent of engine thrust and 12 percent of wing lift.
So most of the fancy , combat specs ,pay load and range figure mentioned in the glossy brochure wont be achieved in indian climatic conditions.
All tejas specs are for indian hot climate, but other fighter maker's specs are for IDSA temp which is far less than indian atmospheric temp.
Close coupled canards are discarded in all fighters from latest fighters from Russia(SU-35) and F-35, F-22 from US, because of RCS concerns arising from latest gen ASEA radars,
the cranked delta of tejas also does the same job done by canards i.e vortex creation o delay flow separation.
And LEVCONS(like in PAKFA) can do the job of canards without giving extra radar reflection like canards.
canards also have may tricky control issues like force coupling and pilot induced oscillation which restrict the efficiency of wing.
And there are many types of canard arrangements like close coupled on rafale and long momentum arm like typhoon , each of them having their own tricky control issues.
canards were considered on F-35 and later dropped.
Even for the evolution of F-16 ino F-16 XL its designers chose cranked delta like tejas , with concerns over RCS emissions from canards. Also in canard arrangements canards are designed to stall before the main wing, so the main wing never achieves its full efficiency.
There are already some videos on the net with two gripen pilots facing the pilot induced oscilation problem peculiar to canards and let the plane crash unable to recover from it.
Eventhough later it was claimed that this problem was resolved, we don't know how it was done or whether any flight envelope restrictions were added because of this.
That is the reason why US and Russian fighter designs always rejected canards in their latest 5th gen fighters and are employing compound delta with levcons(same arrangement proposed for tejas mk2).
The Chinese J-20 was a copy of the rejected mig 1.44 delta canard stealth version(in favour of LEVCON , compound delta in pakfa exactly present in tejas mk2).
So redesigning tejas with canards will be an extremely job throwing its induction into jeopardy.
Also the reason cited by ADA for not including canards was,
1.it will add 3 feet to fuselage length,
2,It will add more weight .
3.During wind tunnel testing for the small airframe design of tejas , it did not give any considerable performance enhancement for the above two penalties it imposed.
It is pertinent to note that gripen C which had canards is 300 Kg more in empty weight in tejas and 3 feet longer in length.
In indian hot atmospheric condition which already saps 12 percent engine thrut and lift this added weight and drag will make tejas further underpowered.
Also in a quest to make gripen E more of an MMRCA new fairings were added to it further increasing drag and now it weighs more than 7 tons in empty weight.
But the path chosen for tejas mk2 is very simple. Add 0.5 meter in fuselage to smoothen the cross section increase between 4 and 5 meter lengths in fuselage and retain the same design and go for further weight reduction by increasing the percentage of composites to more than 50 percent.
It will make teja mk2 far more effective and developmental path would be very short and less complex with no time over run.
It will be nice if Air Marshal barbora clarifies his view on these point raised here.
apart from work share with HAL....
