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FA-50 and JF-17 are the finalists for Malaysian Air Force's Deal: Korea Times

MirageBlue

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Disagree with the second part since that also depends upon configuration - but yes, more often than not AB is used for takeoff.

Hi-lo-lo-hi the thunder is good for 300 miles on internal alone - add centerline to get 50 and wing tanks to get 120 more - but that too is VERY subjective.
Yes, maybe they can use up a large part of the runway when they're flying with 2 dummy missiles, but if they're carrying any meaningful payload, they'll find it hard to take off without using the AB. Almost every single video/pic I've seen of fighters taking off, they're using AB to get off the ground.
 

m52k85

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Almost every single video/pic I've seen of fighters taking off, they're using AB to get off the ground.
Thats because all videos out there are from airshows, where the take-off, even being in clean config, is done on after-burner to put on a show.

If you have a video of USAF taking off from Udeid or French Airforce taking off to strike in Western sahara, please post it.

Coming back to your method of calculation using TSFC, that number is not a constant, it changes with altitude (get better), the numbers you see on brochures is at sea level, and is only meant to compare the relative effieciancy between different engines and not to estimate combat ranges. Using TSFC the way you did will therefore not give an upper bound on range because of this reason.

Some references to get you started off:
" The value of TSFC for a given engine will vary with speed and altitude, because the efficiency of the engine changes with atmospheric conditions. "
 

MirageBlue

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Thats because all videos out there are from airshows, where the take-off, even being in clean config, is done on after-burner to put on a show.

If you have a video of USAF taking off from Udeid or French Airforce taking off to strike in Western sahara, please post it.

Coming back to your method of calculation using TSFC, that number is not a constant, it changes with altitude (get better), the numbers you see on brochures is at sea level, and is only meant to compare the relative effieciancy between different engines and not to estimate combat ranges. Using TSFC the way you did will therefore not give an upper bound on range because of this reason.

Some references to get you started off:
" The value of TSFC for a given engine will vary with speed and altitude, because the efficiency of the engine changes with atmospheric conditions. "
I wasn't referring to air shows. of course Air shows are about maximising and demonstrating performance, so Afterburners are generously used. but even during regular squadron sorties, I've always seen afterburner in use during take off. Even for fighters like MiG-29 that are lightly loaded and high on dry thrust itself.

In the heat of the desert, the airplane's performance degrades. The hotter it is the harder it is to take off with a decent payload without using AB. Hot and high being the worst conditions. For e.g. Leh AFS in India, which is both at very high altitude and hot in summers.

That brochure number could be the most efficient number or it could be the worst number. Either way, it is worthless without knowing what assumptions went into it, what configuration it was with, what the mission profile was and so on.

These figures are for gullible public consumption at air shows. Those who are in the know from Air Forces know that these numbers are not a constant and cannot be taken at face value just as it is.

Also, what you're referring to, that SFC changes with speed and altitude is true, but without then knowing the exact speed and altitude THROUGHOUT the mission, one cannot calculate the combat radius at all..hence, the only way to do it is to use an average SFC.

And I have used that technique to calculate Block Fuel for airliners at one of the world's largest Airline manufacturer. We have provided the full mission profile, with the fuel consumed in each segment of the flight that way, using an average SFC for the engine. Otherwise it quickly becomes so complicated that no one will understand how a particular Block Fuel (fuel required for a mission from taxiing to landing) is calculated.

The link that you yourself gave had this quote clearly specifying that

Engineers use the TSFC for a given engine to figure out how much fuel is required for an aircraft to perform a given mission. If the TSFC = 0.5, and we need 5000 pounds of thrust for two hours, we can easily compute the amount of fuel required. For example,

5000 pounds x 0.5 pound mass/hour/pound x 2 hours = 5000 pound mass of fuel.
 
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MastanKhan

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Could be..but then again, it is not a FIXED NUMBER.

It all depends on what is the Mission Profile..HI-HI-HI mission profile leads to a different combat radius number than HI-LO-HI or HI-LO-LO, since fuel burn and drag is different at different altitudes.

It also depends on the payload being carried, their total drag index and whether one expects to be refueled mid-air.

There are so many factors that one needs to consider, but people here on PDF make it sound like it's as easy to come up with, as a car's mileage in perfect conditions around a race track..


Afterburner is almost always used to take off. Most of these fighters don't have the thrust to take off on simply dry thrust.

If you expect to encounter opposition, you need to keep reserves for at least 1-2 minutes of Afterburner use. It is a question of Mission Planning.
Hi,

Combat radius is what it is. It does not change much.
 

krash

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Yes, maybe they can use up a large part of the runway when they're flying with 2 dummy missiles, but if they're carrying any meaningful payload, they'll find it hard to take off without using the AB. Almost every single video/pic I've seen of fighters taking off, they're using AB to get off the ground.
It has more to do with the required safety protocols during take off which are dependent on the runway length, then temperature and altitude. Ideally, takeoff roll is kept under 50% of the runway for both the F-16 and the F-15 in case of an aborted takeoff.

3.6.6 Make an afterburner takeoff anytime the computed MIL power takeoff roll exceeds 50 percent of the available runway.
AIR FORCE MANUAL 11-2 F-16 Volume 3

3.7.2 ...For single ship takeoffs, if the single ship computed military power takeoff distance exceeds one-half of the available runway, takeoff using afterburner.
AIR FORCE INSTRUCTION 11-2F-15 VOLUME 3


 

VkdIndian

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Thats because all videos out there are from airshows, where the take-off, even being in clean config, is done on after-burner to put on a show.
Most of the times a fighter getting airborne for any meaningful mission is likely to be carrying adequate amount of weapons and fuel. This is likely to be close to its max weight takeoff capability most of the time. When getting airborne at such weights use of afterburner is mandatory for getting airborne safely.

Unless aircraft is getting airborne for a specific mission that requires it to carry a single bomb then it is a different story. But such a scenario is likely to be an exception.
 

Goritoes

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God's help out Malaysian if they gone for Tejas.

Plateform for which even indian airforce and Navy have reservations
It comes with a Free Truck, any other fighter can claim this? NO only our Teja bhai has that speciality :D
 

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