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[CORRECT BASED ON AVAILABLE CHARTS] Underpowered ?


FastNotFurious
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Hi buddys isn't the plane underpowered ?

 

When I look at the specifications of the real plane, we can see that it is supposed to reach 72,000 feet / minute :

 

https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Specifications_(F-16C_Block_50/52)

 

I know that is in an optimal configuration and not really the same IRL, but in the game, empty wings with very little of fuel, it's not even close to 25,000 feet / minute

 

Here, we have a real F-16 pilot who claims that the model flight is underpowered : https://youtu.be/rtAVvQ6mPDA?t=1147

 

How to explain the huge gap between the specifications and the plane in game, is there as big a gap in speed as that ?

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All aircraft in DCS to a greater or lesser extent have too much drag, no matter the config.

 

Just try gliding any aircraft at best L/D AoA and watch as it bleeds speed, unable to glide as it should (engine idle or shutdown completely - makes no difference).

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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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Yes, it's horrible, this should be priority nr.1 on the fix list. I did see one block15 on an airshow that did climb to angels 30 in 30 seconds.
Well that's faster than the raptor. How do you know he hit 30,000 feet?

 

Sent from my SM-N950U using Tapatalk

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30,000 ft in 30 seconds is "only" 60,000 ft/min or "only" 83% of its stated maximum performance.

 

 

If he entered the vertical from 600+ kts at max power, why not? 600 kts = 60,760 ft/min in the forward direction.

Motorola 68000 | 1 Mb | Debug port

"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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'Not' because that climb rate is only an initial climb rate. You'll lose that very quickly going up as pressure falls and therefore engine thrust is also reduced quite severely.

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One thing to keep in mind is that the Block 50 is heavier than previous versions, and so it'll have worse climb performance generally than older F-16s. A quick Google search turns up climb rate numbers all over the place, from the mid 30,000s to to around 50,000 ft/m. Wikipedia's claim of 72,000 ft/m is by far the highest I've seen, and though they claim it's for the Block 50/52, I'm skeptical.

 

Mover has also mostly flown older blocks of F-16s as well, so he's comparing it to a lighter jet. He does say the drag model is something they're working on, the video is 8 months old, I'm not sure how different the flight/drag model currently is from what it was then.

 

To be clear: I'm not saying there is no problem with DCS here, just that the issue is a bit more complex than it may seem and there are other contributing factors.

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A 36klb F-16 GE-129 with DI 0 at sea level 15C should accelerate by pitching to 12 degrees and then level at 2500' to MAXAB climb airspeed in 0.9 minutes from brake release. The MAXAB (590 KIAS/0.95 IMN) climb then takes another 1.8 minutes to 40,000' (from sea level so shave a tiny bit off because 0-2500' was counted twice).

 

So there's your test. Can you go from brake release to 40,000' in 2.7 minutes given the above ISA atmosphere, GW, and procedure?

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Is that a vertical climb (+90 deg. pitch) after the acceleration?

 

What g to pull to go vertical?

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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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If 72,000ft/m is anywhere near accurate it will be 'initial' climb rate. The Hornet has a listed initial climb rate of 50,000ft per minute that has been reported since before the EPE motors were even a thing. It's not anything that could be sustained and I don't think it is a useful metric.

The F-16 in DCS is a rocketship, IMO.

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A 36klb F-16 GE-129 with DI 0 at sea level 15C should accelerate by pitching to 12 degrees and then level at 2500' to MAXAB climb airspeed in 0.9 minutes from brake release. The MAXAB (590 KIAS/0.95 IMN) climb then takes another 1.8 minutes to 40,000' (from sea level so shave a tiny bit off because 0-2500' was counted twice).

 

So there's your test. Can you go from brake release to 40,000' in 2.7 minutes given the above ISA atmosphere, GW, and procedure?

 

 

Trying to hold .95 to 40k. Seems a little slow to altitude according to those numbers?

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The procedure I recall is 350kts until you hit M0.95 and 0.95 thereafter. No climb to 2500', release brakes, take-off, accelerate to 350 ASAP (level off right after T/O) and follow with 350 to 0.95.

 

In any case, is the atmosphere set as required in your test, are you at the required GW?


Edited by GGTharos

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I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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Anybody that uses wikipedia specs to complain about performance needs to be repeatedly slapped. Hard.

 

 

when a real pilot with hundred hours on F-16 confirms this assumption, you should rather listen, nobody here has ever flown an f-16, so better slap yourself :book:

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Trying to hold .95 to 40k. Seems a little slow to altitude according to those numbers?

 

Good technique.

 

The procedure I recall is 350kts until you hit M0.95 and 0.95 thereafter. No climb to 2500', release brakes, take-off, accelerate to 350 ASAP (level off right after T/O) and follow with 350 to 0.95.

 

In any case, is the atmosphere set as required in your test, are you at the required GW?

 

The procedure in the performance data is 12 pitch until 2,500' and level accel to the climb schedule. That's isn't an operational practice just a technique for the purposes of the performance tests and comparison. Air temp being 20 or 15C makes a very small difference. I don't know where you're getting 350 knots from. MAXAB climb schedule is much, much faster.

 

However I'm sorry for making that 36klb GW since that's impossible without external stores and I assumed DI 0. The times and climb schedule are different for that DI (I think two tanks is ~150). A clean airplane (pylons removed but I hear that isn't modeled yet) with 96% internal fuel is 27klb.

 

However even at 35klb / DI 150 the climb portion should have taken ~1.75min instead of the almost a minute extra it did.

 

Figures for the 27klb clean airplane are:

0.7 min to 2500'

0.5 min to 20kft (from SL)

1.2 min to 40kft (from SL)

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SAF did the following (rutowski) profile for evaluating f16 vs f18epe.

 

F-16 profile (4*aim9L) from break release to 49’000ft and M1.4 :

 

1) TO, accelerate to peak acceleration (~m0.9).

2) Gently pull and climb while holding M0.9 to M0.95 .

3) Level off @ 28’000ft and accelerate thru sound barrier (hold -0.5g) to mach ~ 1.2. -0.5g phase lasted ~ 45s...

4) climb to 49’000ft and M 1.4.

 

The profile took 3min. and 7 sec. for the F16 in rw and 4min 9sec. For the f18 epe with 2*aim9 & 2 a120.

 

I tried this profile with dcs block 50( 26000lbs, 4*aim9. 15deg C )

40kft took 2min 20sec.

49kft took 3min. 3. Sec

f16 climb 49000 m1-4.trk

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Anybody that uses wikipedia specs without double-checking the given sources thrice to complain about performance needs to be repeatedly slapped. Hard.

 

Corrected that for you kthxbye. Oh wait... yes, all those books are terribly wrong! The Great Aero once said: "Where did you read about Spitfire made from a wood? Close this book forever and never open it again!"

 

I can't even get to the M 2 given here since a few patches ago. Limit is just shy of 1.8 on a standard DCS day in Caucasus for a clean airframe just running out of fuel. But as the title sais, this is correct based on available charts icon_exclaim.gif

dcsdashie-hb-ed.jpg

 

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No problems here. Clean jet.

Screen_200617_070706.thumb.jpg.e17ea42c323fd493589abf56b3e736dc.jpg

Screen_200617_070822.thumb.jpg.7abd8eec16609599cdfc2f87e318f9df.jpg

Screen_200617_070917.thumb.jpg.7887eae73a61e70e476f22ddb0d0b8c3.jpg

Motorola 68000 | 1 Mb | Debug port

"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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But you're losing altitude in those pictures. What's it like in level flight?

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when a real pilot with hundred hours on F-16 confirms this assumption, you should rather listen, nobody here has ever flown an f-16, so better slap yourself :book:

 

There are lots of real pilots here, actually, including for aircraft flown in the game... none of which has anything to do with citing a wikipedia spec page as evidence, which is a red flag for ''this person has no idea what they're talking about''.

 

As for Mover, yeah, his thoughts are of course relevant, nevertheless, it's fairly straightforward to verify: find charts, compare results. If the results are accurate (or very close) then feelings are irrelevant at that point. Math is math.

 

As others pointed out, 70k a min is initial climb under ideal conditions, that does not apply across the entire arc, nor does it apply to all atmo conditions or flight profiles (or models). So, actual performance charts (not an idiotic generic statement sans qualifiers) followed by a roughly similar flight to test. If the results are plus or minus a few percent, it's safe to assume it's correct.

 

Note: as ED are also capable of basic math, they usually don't need forum jockies to tell them these things. They do make mistakes or miss stuff that the community catches, but that's the exception, not the norm. This is the sort of stuff I'm inclined to believe they're capable of basic reading, math, and following the instructions for a certain profile.


Edited by zhukov032186

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But you're losing altitude in those pictures. What's it like in level flight?

 

A bit of background as to why it is done this way:

 

Mach number is affected by temperature ONLY.

 

The reason is as air temperature reduces (gets colder), air density INCREASES.

 

However, as we climb, there is less air pressure. Air density REDUCES.

 

The consequence is this ratio of pressure change vs. temperature change is such that they cancel each other out (in the atmosphere), so the only factor affecting Mach number is change in temperature.

 

That's the basic physics...

 

The local speed of sound (LSS) at sea level on a standard day is 661 kts. To fly at Mach 1.0 you would need to be doing 661 kts TAS.

 

The tropopause starts at 36050 ft (average), and this is where a curious feature of the Earth's atmosphere begins.

 

Between sea-level and the tropopause the temperature reduces at a lapse rate of roughly 2 deg. C per 1000 ft of altitude, but above the tropopause the temperature is constant, at approximately -56.5 deg. C.

 

At 35000 ft the LSS is 574 kts.

 

To make matters a bit more complicated, we use CAS (Calibrated Air Speed) which is computed by measuring the pressure of the air entering a pitot tube as we fly forwards.

 

As we fly higher, the air gets thinner, meaning that for every 100 kts of forward airspeed we have, there is less air entering the pitot tube, so the pressure is lower at 35000 ft than at sea level, meaning our measured airspeed reads lower than our TRUE AIR SPEED.

 

Remember what I said about Mach only being affected by temperature?

 

CAS is affected by density and pressure!

 

As we keep climbing, and as we approach, and exceed, the speed of sound, things get very funky indeed, and so we need to deal with it (compressibility effects).

 

Extreme example: if we could keep climbing into space (vacuum) the CAS would eventually read zero, which obviously isn't the real situation).

 

On top of this, we start running into other problems, like lack of thrust. The engine needs air to produce thrust, and at altitude we can compensate by flying faster for a while, but things like drag get in the way, limiting our ultimate velocity.

 

So... what does this mean?

 

As we climb, our CAS gradually reduces for a constant TAS.

 

As we climb, our Mach number increases for a constant TAS (up to 36050 ft).

 

If we climb from sea level to 35000 ft at Mach 0.95, then at 35000 ft we must level off, and accelerate through Mach 1.0. This is a very high-drag regime, and requires lots of thrust and time.

 

Once we are through Mach 1.0, we actually enter a lower drag regime, and things can go more smoothly again.

 

If we try and achieve Mach 2.0 from here, it will take probably more fuel than we have, due to the time required to accelerate.

 

The acceleration profile requires then that we do two things:

 

* Achieve greater than Mach 1.0 flight at a lower altitude to get through the high drag regime when we have more thrust

 

* Climb above the max Mach altitude so we can use gravity to assist the acceleration to Mach 2.0.

 

So at say 30000 ft we accelerate to Mach 1.4, where we continue our climb at that Mach number (constant Mach climb) all the way up to 50000 ft, where we begin a gentle push-over to reduce g, reduce drag, and maximize acceleration rate.

 

We then lower the nose below the horizon slightly to get the assistance of gravity on the way down, as well as descending into thicker atmosphere helping thrust, and eventually heading towards the altitude of maximum Mach number (~35000 ft).

 

You might have heard the term "unloading the jet". This means pushing so the g loading experienced is zero. The effect of doing this reduces the angle of attack, causes the LEF to streamline to the zero angle position, and cleans the aircraft up to minimum drag profile, resulting in maximum acceleration. This applies for most aircraft generally.

 

Unfortunately, we can't maintain zero g forever as we would eventually achieve an outside loop, but it is usful for passing stages such as recovery from low speed flight (100 kts), and accelerating through the trans-sonic region (somewhere around Mach 0.80 to 1.25). Obviously, you don't do this if it would result in a crash or other unfavorable situation.

 

Below Mach 0.80 and above Mach 1.25 the aircraft experiences less drag. Around Mach 1.0, the aircraft is experiencing high drag as a shockwave forms ahead of the aircraft, but the aircraft is not yet fast enough to catch up to the compressed air ahead of it.

 

"Breaking the sound barrier" occurs because the aircraft is now flying faster than the air ahead of it, and the sonic boom is the air uncompressing at the speed of sound (it is like releasing a spring from compression suddenly).

 

At 50000 ft I was able to accelerate to Mach 1.7 without too much trouble, then I descended to accelerate the rest of the way.

 

If you look at the fuel used, you can see I used relatively little fuel to get to Mach 1.7 at 50000 ft, but then I used 1500 lbs just to get from Mach 1.7 to Mach 2.0.

 

One of my favorite things to do in any aircraft I fly is try and find the most optimum/fuel efficient flight profiles, so at any given time I use the least amount of fuel.

 

High drag means fly slower. You can't brute force your way through the drag! It just burns fuel. Depending on the drag index, there is a maximum IAS and TAS (or Mach number) above which it becomes inefficient to fly.

 

For a clean F-16, subsonic that limit is 350 kts or Mach 0.95; supersonic it is Mach 1.4-ish, though 1.6 can be achieved with little effort.

 

A good guide as to most efficient speed is to look at the best glide speed. For any given configuration (drag index) and gross weight, there is a speed which results in the lowest drag for the most lift. This is where you will find the maximum endurance speed.

 

Maximum range speed is slightly higher (yes, you burn more fuel, but you also travel further), while minimum sink is a bit slower (the speed at which the aircraft loses the least amount of altitude per unit distance travelled forwards).

 

Generally, there are three speeds. In order of slowest (speed) to fastest:

 

* Minimum sink rate

* Maximum time (endurance)

* Maximum distance

 

We are generally concerned with maximizing our flight time (loiter time). We can balance it with maximizing our distance, but this usually applies to ferry range. We care about maximum distance if we are gliding, and we balance this with the maximum endurance speed. For a clean F-16 this is around 236 kts.

 

If we need range in combat, we use tankers.

 

Note that more WEIGHT = higher glide speed, BUT NOT MORE GLIDE RANGE!

 

The heavier aircraft glides faster, but it will not glide further. Conversely, a lighter aircraft will glide slower but it will not glide SHORTER!

 

As long as you are at best glide speed, you are doing all you can to maximum your glide distance.

 

In the F-16, clean, if it is at 6 degrees or lower in the HUD, you can glide to it (winds permitting!!!).

 

 

This turned into a bit of an essay, but I hope it was useful!


Edited by Tiger-II

Motorola 68000 | 1 Mb | Debug port

"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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One thing to keep in mind is that the Block 50 is heavier than previous versions, and so it'll have worse climb performance generally than older F-16s. A quick Google search turns up climb rate numbers all over the place, from the mid 30,000s to to around 50,000 ft/m. Wikipedia's claim of 72,000 ft/m is by far the highest I've seen, and though they claim it's for the Block 50/52, I'm skeptical.

 

Mover has also mostly flown older blocks of F-16s as well, so he's comparing it to a lighter jet. He does say the drag model is something they're working on, the video is 8 months old, I'm not sure how different the flight/drag model currently is from what it was then.

 

To be clear: I'm not saying there is no problem with DCS here, just that the issue is a bit more complex than it may seem and there are other contributing factors.

 

You are wrong. The GE-129 powered block 50 is the best climber among all F-16 blocks.

 

According to HAF block 50 flight manual, a block 50 at sea level, clean, 2500 lbs fuel has an initial climb rate of 1200 ft / sec, and still maintaining a 4.5G turn! The 72000 ft /min seems to be a direct conversion of the initial climb rate and does not take the dissipation over altitude into account.


Edited by oldtimesake
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There are lots of real pilots here, actually, including for aircraft flown in the game... none of which has anything to do with citing a wikipedia spec page as evidence, which is a red flag for ''this person has no idea what they're talking about''.

 

As for Mover, yeah, his thoughts are of course relevant, nevertheless, it's fairly straightforward to verify: find charts, compare results. If the results are accurate (or very close) then feelings are irrelevant at that point. Math is math.

 

As others pointed out, 70k a min is initial climb under ideal conditions, that does not apply across the entire arc, nor does it apply to all atmo conditions or flight profiles (or models). So, actual performance charts (not an idiotic generic statement sans qualifiers) followed by a roughly similar flight to test. If the results are plus or minus a few percent, it's safe to assume it's correct.

 

Note: as ED are also capable of basic math, they usually don't need forum jockies to tell them these things. They do make mistakes or miss stuff that the community catches, but that's the exception, not the norm. This is the sort of stuff I'm inclined to believe they're capable of basic reading, math, and following the instructions for a certain profile.

 

 

Sorry but the aggressive and contemptuous manner in which you communicate with other people who innocently ask a simple question (and which is legitimate, given that it is shared by a real f-16 pilot and that it finds echoes right here) as if they had insulted your mother is worthy of a real jockey as you say and proof at the very least of a delay in maturity or of a mental deficiency and does not even deserve that I linger to answer, sorry probably right, I allow myself to write thus since yourself seem to despise decorum grow up boy and learn politeness.

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