Aerodynamics thread

[Hyperwarp]

In terms of supercruise for the F-22, it seems it has a radius of about 100 nm (185 km) with 2x 600 gal tanks. I guess we can double that if we just take a straight line (at least 370 km). Without the tanks, it is probably around 60 nm to 70 nm radius. But we do not know the speed in which this was achieved. At max supercruise (Mach ~1.8), I doubt it is anywhere near that distance.

 

[Blitzo]

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Please take a look at their official website and see how their show interface is usually formatted.

Again, the phrase “One Minute” is completely separate from whatever other message says.

I have no idea what the part on the J-20 covering 52 km means either. That’s why I specifically asked about that in my first post...

Once again, I suggest that we should be careful when interpreting the photo posted on the last page. We don’t want to be the ones who started spreading wrong info.

In the photo, a tv series named “One Minute” claims that the J-20 can combat cruise for 52 km. That’s it.

It does NOT mean “the J-20 can cover 52 km in one minute”. It does not.

Actually I think that is exactly the claim the show is making. If you read the full thing on the page, you can see how it says "in one minute the gulf of aden task force moves 920 meters" and "in one minute a tank advances 600 meters".

That is to say, everything that is described in the page and on the show in that format is meant to relate back to "one minute" -- i.e.: "XYZ can be done/XYZ distance can be crossed, within one minute".... and different things that can be done "in one minute" for soldiers, for artillery, for ships, for j-20 etc are all described on that page as well.


Now, this isn't to say that the claim is true because as latenlazy said they might've just taken a baike speed and calculated time = distance/speed to get 52km... but it's pretty clear that they are claiming "in one minute, J-20 can cover 52km".

 

[Inst]

It's either a spurious claim or just a supercruise speed claim. If you get 52 km / 1 minute, the effective speed is 3120 km/h or mach 2.5 at sea level and mach 2.93 at 10,000m altitude.

Given the complex coatings and metamaterials involved, the J-20 should not be able to reach such speeds as it'd require constant reinforcement as well as heatshielding to prevent it from burning up its coatings.

 

[Blitzo]

It's either a spurious claim or just a supercruise speed claim. If you get 52 km / 1 minute, the effective speed is 3120 km/h or mach 2.5 at sea level and mach 2.93 at 10,000m altitude.

Given the complex coatings and metamaterials involved, the J-20 should not be able to reach such speeds as it'd require constant reinforcement as well as heatshielding to prevent it from burning up its coatings.

Regardless, the point is that the website and the feature video most certainly did intend to say in one minute, J-20 crosses 52km.

I don't think the numbers add up but that isn't relevant.

 

[Hyperwarp]

Regardless, the point is that the website and the feature video most certainly did intend to say in one minute, J-20 crosses 52km.

I don't think the numbers add up but that isn't relevant.

So can we now confirm supercruise for the J-20? I don't know about the 1-minute value, but it sounds like the J-20 can dash at least 50 km at a possible max supercruise speed. Now the questions are,

Was this an in-service J-20 powered by the Salut AL-31 variant or is it a prototype (#2021, #2022) with the new WS-10 variant?
What was the max supercruise speed and was the J-20 loaded fully with fuel and weapons?

Neither the AL-31 or WS-10 would have the dry-thrust of the AL-41F1 (let alone F119) nor the efficiency of F119, EJ200, etc when it comes to supercruise, however, this is a very good sign for the J-20 design team. Even limited supercruise with crappy engines means the J-20 as a design is a success. I think it was latenlazy who said supercruise is not just about the dry-thrust and more about drag (apologies if I misrepresented you there). Now bring on the WS-15.

The F-22 at can supercruise Mach 1.72 (15% exceeding the ATF requirement) with acceptable range and max supercruise of around Mach 1.8. At Mach 1.5 with full load of fuel and weapons, it probably can dash over 200 km in supercruise.

 

[Blitzo]

So can we now confirm supercruise for the J-20? I don't know about the 1-minute value, but it sounds like the J-20 can dash at least 50 km at a possible max supercruise speed. Now the questions are,

Was this an in-service J-20 powered by the Salut AL-31 variant or is it a prototype (#2021, #2022) with the new WS-10 variant?
What was the max supercruise speed and was the J-20 loaded fully with fuel and weapons?

Neither the AL-31 or WS-10 would have the dry-thrust of the AL-41F1 (let alone F119) nor the efficiency of F119, EJ200, etc when it comes to supercruise, however, this is a very good sign for the J-20 design team. Even limited supercruise with crappy engines means the J-20 as a design is a success. I think it was latenlazy who said supercruise is not just about the dry-thrust and more about drag (apologies if I misrepresented you there). Now bring on the WS-15.

The F-22 at can supercruise Mach 1.72 (15% exceeding the ATF requirement) with acceptable range and max supercruise of around Mach 1.8. At Mach 1.5 with full load of fuel and weapons, it probably can dash over 200 km in supercruise.

No I don't think we can confirm anything.

We don't know if the "52km in one minute" thing is actually a legitimate number relayed by the air force or CAC or anyone, or if whoever was in charge of marketing just threw out a number taken from the internet and did a bit of simple arithmetic.


In other words, it is probably best for us to pretend that the "52km in one minute" thing doesn't exist until we have a reason to take it remotely seriously.

 

[latenlazy]

So can we now confirm supercruise for the J-20? I don't know about the 1-minute value, but it sounds like the J-20 can dash at least 50 km at a possible max supercruise speed. Now the questions are,

Was this an in-service J-20 powered by the Salut AL-31 variant or is it a prototype (#2021, #2022) with the new WS-10 variant?
What was the max supercruise speed and was the J-20 loaded fully with fuel and weapons?

Neither the AL-31 or WS-10 would have the dry-thrust of the AL-41F1 (let alone F119) nor the efficiency of F119, EJ200, etc when it comes to supercruise, however, this is a very good sign for the J-20 design team. Even limited supercruise with crappy engines means the J-20 as a design is a success. I think it was latenlazy who said supercruise is not just about the dry-thrust and more about drag (apologies if I misrepresented you there). Now bring on the WS-15.

The F-22 at can supercruise Mach 1.72 (15% exceeding the ATF requirement) with acceptable range and max supercruise of around Mach 1.8. At Mach 1.5 with full load of fuel and weapons, it probably can dash over 200 km in supercruise.

I’d say the 52 km/min number is *highly* suspect (even if it were accurate it’s unlikely to refer to cruise speed with dry thrust), but you had me right about supercruise not just being a function of dry thrust. That point, at least, is a matter of physics. That doesn’t mean we can definitively say the J-20 in its current state can supercruise, just that we can’t definitively say that it can’t. For what it’s worth pilots have talked about the J-20’s superb supersonic maneuverability before which would at least imply that it has conducted combat exercises in that flight regime. That, and Song Wencong making mention of achieving supercruise with inferior engines is pretty much all we know for sure about the J-20 and supercruise.

 

[Jura The idiot]

One minute: J-20 fighter cruised 52 KM.

View attachment 48166

From: People's Daily "Solider One Minute"
人民日报八一推出的微视频《军人一分钟》

I located the picture through images.google.com which led me to
官方披露我军歼20飞行速度：1分钟内战斗巡航52公里

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an automatic translation of the first paragraph:

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(the rest was quite interesting, too, but I'm not going to put it into the translation window again)

 

[ougoah]

I assumed Mach 1 to get a maximum time in "supercruise" for 52km distance traveled. Of course there are other things to consider and if all true, J-20 obviously supercruised at a faster speed and for a shorter duration.

 

[guanyu158]

Me neither.

The show is about what military person can do in one minute. So cruising 52km in one minute is correct interpretation.