insight into low drag problem of Jeff?

I watched it. I have never had the highest confidence in Cap’s testing. Taking into account that the FM is supposed to be within 3% and let’s say a random 2.5% testing error I don’t think the results are showing anything super off. The JF-17 is 80% the weight of F-16 with less wing loading meaning far better fuel burn per mile.

Take a look at the pictures below, the JF-17 has a significant downward camber of the portion of the root behind the wing and in front of the stab. Other planes with enlarged roots like F-16 do not have this. Not saying this is what’s causing it’s efficiency, but one of many factors such as low wing loading that play into this

I think the JF-17 being as small as it is with low wing loading owing to its huge strakes is just pretty fuel efficient. I know Cap thinks it’s not possible for something to be have stats better then F-16 but I’m pretty sure he would agree a Toyota Corolla can be more fuel efficient then a Toyota Camry.

A quick google finds that the published ferry range is 2163 miles(EDIT: source https://www.pac.org.pk/jf-17), extremely close to his tested ferry range of 2216 miles, I think that’s pretty well within margin of error. A quick search on wing loading would’ve helped him understand why it’s sustained turn rate was so good in the turn rate test also. It does best the F-16 in certain parameters, it is not impossible. (EDIT: only can find one source on wing loading, 24.4m squared, if anyone wants to calculate in comparison to viper http://www.jf-17.com/specifications/)

I honestly think he tries to keep finding something wrong with the JF-17, every test against F-16 when JF-17 performs well he says it can’t possibly be right that something must be wrong with the modeling, he pretty much even admits his bias a few times(props for honestly though). So I’m not going to take it to seriously, I feel comfortable with the JF-17 performance even if I’m taking his numbers at face value

Don’t want to start anything, GR has improved over time, these are just my thoughts as to why he saw what he did

Can't agree more. Cap's vids are getting lower and lower quality over the time. I used to watch them just for fun. Now I don't even watch them at all. Not because they are not fun, just because they are not very informative. I was watching the F18-Independence Day vid the other day. The guy just said the F18 is FBW so, why two hands on the stick? So asked a guy who's real f18 driver, remember he told me that the shape of the stick is made so at high speeds and tight turns you would have to use both hands. My friend just posted a commentary on his youtube vid pointing out even where to find if that, (NATOPS included) but hey, we are all wrong...

What is it with these people?!

Sheesh - yes guys - someone can build better performing aircraft than the USA!

Learn how to fly/fight/survive like reality and you'll do better than relying on SPAMRAAMs or other game mechanics to save you.

Jeff has only been out a couple of months and this nonsense is getting boring already.

If you really want a complaint to raise with ED/Wags, tell them the overall drag model is too high (particularly F-18 and F-5).

As for Jeff - the drag model is too high there as well when you start adding anything to the pylons.

Try idle descents in all these aircraft from 35000 ft as they're meant to be flown. You'll end up short of your descent point every time. They all need the nose lowering more than they should to maintain airspeed, significantly reducing glide distance.

F-5 is by far the worst. It can't make its published top speeds without serious effort (wrong), and has very poor glide range vs. reality.

I'll give it to Cap for doing a lot of work. However, the methodology of these tests is deeply flawed if his purpose is to validate either the flight model or maximum ferry range of any of the aircraft. At best they compare the aircraft to each other under arbitrary conditions and not those based on the flight tested performance of the actual jet. It has some entertainment value but is rubbish for the stated purpose. That means it has zero validity for flight model testing.

First off, ferry range is a press release number. Few details about how the number is chosen are specified. Things like: max fuel load or max weight at departure, wingtip missiles or clean, empty pylons installed or removed, burner or mil power takeoff, climb schedule used, cruise mach - variable or fixed, cruise altitude - max range cruise climb or constant altitude or step climb, descent profile used, and the criteria for terminating the test (fuel remaining, altitude, etc). Every last one of these will affect a number that is at best a WAG.

The takeoff, climb, cruise, and descent criteria are of maximum importance. The difference between doing a cruise climb vs a step profile is going to be significant but huge compared to a constant altitude.

Yet, these tests are a random TLAR climb profile at a fixed altitude that is proclaimed as gospel. Nope, sorry, that simply doesn't float except to compare those specifics to a different type of jet flown to the same profile.

I'm with AeriaGloria. I don't want to start anything either but this is not even a measure it with a micrometer, mark it with a grease pencil, and cut it with an axe situation. It's simply random/TLAR methodology dressed up as supplying useful data. It has entertainment value.

@ AeriaGloria in your link http://www.jf-17.com/specifications is show a FerryRange of 1,266 miles for the jF17 in specificantions. thats far away from 2216 miles :D

analiyse is well done...in the way like this on... thrust to Drag curve

and ALPHA is a good point!!!!!! every Plane has high Alpha in low speeds !!!

Deka Ironwork Simulations have to study some aerodynamics :D

lot of physik in they Product are Magic

Magic, the first source I linked is the official manufacturer PAC Kamra and they state a ferry range of 1880 nautical miles which is 2163 imperial miles. That’s not even the highest ferry range I can find.

All the different ferry range numbers you can find are probably from what Tiger and Tweet said, different tests with different parameters.

Regardless there is certainly some angle of attack problems. I've seen my flight path marker sit above my boresight for extended periods while climbing. That should not be physically possible in my imagination.

Regardless there is certainly some angle of attack problems. I've seen my flight path marker sit above my boresight for extended periods while climbing. That should not be physically possible in my imagination.

Hmm this depends on config.

Boresight is "along the longitudinal axis". The FPV shows the current flight path, and depending on the angle of incidence and lift, it's possible for it to be higher.

I agree that certain tweaks may still be needed, the low drag in low altitude did have to be fixed in the first patch.

Just as a curiosity I looked up if there were any references about JF-17 and zero-AOA life and I found an academic CFD paper showing zero AOA lift at subsonic speeds(but interestingly not supersonic, unless I’m reading it wrong), I’m messaging a moderator to see if I can post the link here, don’t want to violate 1.16.

There is also several great papers about its intake including one that analyzes the effect of the passive boundary layer removal system, however that is the only one that is behind a paywall, OT I know but it seems a lot of University kids like doing CFDs of it, pretty interesting

what is the right Ferryrange?

Defintion of range: "Ferry range means the maximum range the aircraft can fly. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to transport of aircraft without any passengers or cargo."

1,266 miles or 2163 miles and more ferry range can be found on anther pages ??? ... i think it is strange ... not every can be right??

One Comparison:

2163 miles ferryrange by 10997 lbs fuel -> one of hightest range with one of the lowest fuelcapacity (thats Magic) because.. it must be a most economics jetengine ever build put in this plane. oh yeah right jf17 is power by the russian Klimov RD-93 engine that is used in the mig29. (i dont know... is this engine really the most economic power plant at all???)

or the jf 17 has optimum of areodynamik drag -> low drag ( but than shold the jf17 fly mach 2 and above).

my personel feeling is the plane is more acrade than realistic in this stange. (like the Magic performence of the SD-10)

I don’t know what you mean by aerodynamics, the top speed is likely limited by compromises of the DSI.

As your definition of ferry range states, it is not always measured with external fuel tanks, likely causing the variation in numbers available(emphasis on the word “usual” in your definition). I don’t think many fighter jets can claim that every source agrees on their ferry range:)

Edit: According here( https://books.google.com/books?id=Evi27zSfxZcC&pg=PA86&lpg=PA86&dq=gripen+ferry+range&source=bl&ots=xH7eEE0kGz&sig=ACfU3U2Y4-Uaes042gz6ZR5uCDnNlB4Bdg&hl=en&sa=X&ved=2ahUKEwi7-pKKs6LnAhWXCjQIHdKJBNs4FBDoATAHegQIBRAB#v=onepage&q=gripen%20ferry%20range&f=false ) the Gripen C/D has a ferry range of 2,000 miles, not too far off, similar size/weight engine class and internal fuel load, don’t know about it’s external tanks. The ferry range of JF-17 is 8.15% more then that if my math it right based off 2163 miles from PAC website

low aerodynamic Drag ..i mean the shape of the plane produce less Darg to reach high speeds. like the Mirage or 104 starfighter..all mach 2 on above jets.

Let's see...

Some "back of the cigarette packet" says:

10300 lbs with 3 external tanks.

Cruise fuel flow of 3500 lbs/hr giving cruise time of 2.94 hours.

We burn 1000 lbs just getting to altitude: 2.65 hours at cruise.

At Mach 0.70 we manage 420 NM/hr.

420 x 2.65 = 1113 NM max range in the sim currently.

That is with three externals, and dumping tanks when empty.

what is the right Ferryrange?

 

 

Defintion of range: "Ferry range means the maximum range the aircraft can fly. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to transport of aircraft without any passengers or cargo."

 

 

 

1,266 miles or 2163 miles and more ferry range can be found on anther pages ??? ... i think it is strange ... not every can be right??

 

 

One Comparison:

 

2163 miles ferryrange by 10997 lbs fuel -> one of hightest range with one of the lowest fuelcapacity (thats Magic) because.. it must be a most economics jetengine ever build put in this plane. oh yeah right jf17 is power by the russian Klimov RD-93 engine that is used in the mig29. (i dont know... is this engine really the most economic power plant at all???)

 

 

 

or the jf 17 has optimum of areodynamik drag -> low drag ( but than shold the jf17 fly mach 2 and above).

 

 

 

my personel feeling is the plane is more acrade than realistic in this stange. (like the Magic performence of the SD-10)

I thought you were being serious but your SD-10 jibe just says you're trolling.

How did you get 2000 NM ferry range?

By your range stat the sim only achieves 52% of max range, or burns roughly DOUBLE the fuel it is supposed to, meaning the sim drag is TOO HIGH.

Your move...

low aerodynamic Drag ..i mean the shape of the plane produce less Darg to reach high speeds. like the Mirage or 104 starfighter..all mach 2 on above jets.

Yeah low drag can do that. Something can also be low drag with a low top speed. With intakes that can’t move and has to deal with low pressure boundary layer the engineers have to choose if they want low speed or high speed performance.

I updated my post above with a picture comparing it with Gripen, let me know if anything stands out. Some of the info like JF-17 top speed is probably from older info, quite a few places used to incorrectly list Mach 1.8 top speed

Tiger-II ferry range is from post #2 in this thread..

i am not trolling ... i cannot belief it from physics aspekt.. i had study physiks and i am engineer

Then do you also not believe the Gripen C range?

Gripen C data is a good found of you ..equal performence by equal Airplaneparameter :)

OK guys the basic problem here is that some of us think, feel, imagine, can't imagine why, and/or don't believe Jeff can fly this well. There must be something wrong with the flight model....QED. So, lets look for evidence that supports our basic premise that something is wrong with Jeff.

Do any of you see why this approach doesn't ever work? Why is this a faulty process?

Forgive me if you feel picked on but I'm going to take you one at a time. I'm trying to unscramble your critical thinking skills and maybe educate at the same time.

shaHeen: Do you realize there is no fixed relationship between pitch attitude/nose position, "boresight", AOA, and FPM (Flight Path Marker)? Depending on what you're doing in the jet they will have different relationships to each other. In that list one of the things isn't displayed visually. Which one? Here's a hint: you're blaming it as the problem. You leave out G loading which may have a part in explaining what you're seeing.

MagicD: Read my previous comment please. Ferry range is a fairy tale. It depends on so many variables that without stating those variables it is meaningless and untestable. It's validity is only in your mind. Pick one.

GR: I enjoy Cap's videos. He really tries and he provides value in most of them as a first look into the subject. However, they're often imprecise in explanation and show a lack or misunderstanding of several things in aviation. I cringe at some of the (mis)statements of fact but at the same time get something out of them when digging into a new module.

The ferry range test is one of those that miss the mark badly. It does a nice job of comparing the various DCS jets to each other. But it only compares how they perform relative to each other under one specific set of conditions in DCS. There is no connection to the actual jet's performance. That those conditions will favor one over another isn't even imagined. He comes close by recognizing the A-10C won't cruise at 32,500' so he makes a separate category. He has the answer in his hands but doesn't quite take it all the way to a logical conclusion.

The reality is that each of these aircraft will have their own specific takeoff, climb, cruise, and descent profiles that maximize range which is the ferry mission objective. Of course determining if the performance is realistic is unsolvable without knowing what each profile is. The only way to fix the flawed methodology is to have the performance data of the actual flight tests on each jet and compare them to what is possible in the sim.

That isn't what is being done. Based on a premise, an article of faith, that something has to be wrong people toss out their own pet theories. Drag is wrong, fuel burn is wrong, AOA is something something, and on and on while demanding Deka/ED fixes it. Each of the items that are supposedly wrong with Jeff are victim of confirmation bias, faulty thinking, lack of understanding of a very complex subject, and over zealous confidence.

That's not how to test things in the real world. We see a phenomenon that doesn't make sense to us and ask why is it different from what we expect. Then you look for possible reasons and test each. Here we begin with the conclusion and charge off in search of a reason. I've explained how each of these three people come to flawed conclusions but they're not the only ones we see on these forums. A little knowledge, minimal understanding, and a lot of confidence go a long way when headed off in the wrong direction.

How to solve the mystery of whether Jeff's FM is FUBAR? We need the performance data and we need the actual procedures and profiles flown to develop the data. I don't see us getting any of that. The manufacturers and their governments are unlikely to release the data although some may be out there in the public domain. We can certainly ask the module developers to give us the profiles and planning data that their FM is supposed to produce so we can test it. That only would confirm that their FM performs as intended. That would be a good start but I don't see it soothing hurt feelings and expectations. Why not go fly and just enjoy what is while Deka continues developing the module?

I don't have the foggiest if the FM is off in the Jeff. If so, I doubt it's much. It seems to get better fuel burn in the descent than it should but drag does seem to track with expected performance at apparent drag indexes for the externals being carried. It may be a bit too good clean but then it can't do much clean. Based on 38 years of flying jets I think it's believable.

It's roughly 40 years newer than the Viper. A lot has been learned about materials, engines, aerodynamics, aircraft structures, avionics, digital FCSs, computer, hell everything, and China has come a long way to being a modern country capable of building a Viper-like jet. It's not a surprise Jeff contends favorably with the Viper. Its overall visibility out of the 'pit sucks in the rear hemisphere compared to gawd-like vis out of the F-16 but most things feel reasonable for the most part. Still, the FM could be wrong. I could be wrong. I just don't think either is any more wrong than most of the other modules. It's a child of the newest with a dedicated developer who is dedicated to a good product. I'm confident they'll give us something that fits in with the other modules in DCS. None of it is worth getting worked up over.

Gripen C data is a good found of you ..equal performence by equal Airplaneparameter :)

So if I understand you right, you believe 2000 mile range from Saab designed airplane but not from Chengdu/PAC design?

EDIT: I agree with all your thoughts tweet!

My opinion is there are more than a few getting upset that American isn't best, and can't/don't want to think another country could possibly be better.

I'm surprised they're not pleased for a strong RedFor now! They actually have something dangerous to fly against (not that Su-27 or others shouldn't be less dangerous).

Deka: putting the SIM in DCS.

Thanks Aeria. It's always interesting when firm believe backed with complete confidence in being right meets actual data and knowledge/understanding. I keep hoping to educate but well....

It's just good to be back playing with well done modules. And VR, let's not forget VR.

i have no problem to beleive saab or Chengdu/PAC.

but you put some links with sources of differnd Ferryranges. (So that I cannot believe your sources at all)

and my pyhsik problem is: that the jf17 has no Alpha at low speeds with result of higer fuel consumption at low speeds !!!!!

Not sure if you have flown it but it certainly does. When landing it you are supposed to be at 10 degrees AOA, only way to do that is get slow.

Sorry my second link is what’s stopping you from believing it’s possible to perform that way. Not all sources agree on ferry ranges for a lot of jets so I would think you have issues with almost everyone. Without knowing the parameters of each stated ferry range it’s a moot point. I think you would find the case of reported ferry ranges differing to be a very similar situation for the F-16C GE engine outside of official charts. Why Does the Jeff have to be held to a higher standard?

As your definition stated these are not concrete absolute things, they were achieved in a single test with unknown conditions.

EDIT: even charts can disagree, does not invalidate them or mean the lowest is right https://forums.eagle.ru/showthread.php?t=234339&page=33