F-35 vs Su-30/35

The F-35 compared with other modern jets.
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boogieman

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Unread post02 Dec 2019, 12:20

hornetfinn wrote:
zero-one wrote:
gta4 wrote:F-35 normally takes 18400 lbs fuel at stage show engine start. In terms of A/B duration, that is more than the full fuel load of Su-27/35.


The Su-27 carries 20,700 lbs, the Su-35 carries 25,400 lbs at full load. There are many claims that the Flanker carries far less than this at an airshow but I have never seen any official statement that this is the case.


Probably because Sukhoi itself has stated that 5,250kg is the fuel weight for normal take-off weight for Su-27SK and about the same for Su-30MK versions. Data is under "Flight performance"

http://www.sukhoi.org/products/earlier/251/
http://www.sukhoi.org/products/earlier/253/

AFAIK, Su-27 derivatives have pretty significantly lowered G-limits when loaded with full internal fuel. Basically it has large internal auxiliary fuel tank that is not used for normal flight operations but of course can be used when longer range is required. When there is fuel in that tank, the G limits are something like 5G. Naturally when it runs out, then the normal limits apply. So it's very likely that they take off with that normal fuel weight.

Feel like I've heard this before. Do you have a source on this one?
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hornetfinn

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Unread post02 Dec 2019, 12:40

boogieman wrote:Feel like I've heard this before. Do you have a source on this one?


I've found at least this: https://issuu.com/duyenpham9989/docs/ai ... al_2017-04

On page 52 the Auxiliary Fuel Tank is described in the red box. That article looks pretty good and accurate (and has some great pictures of Flankers!).
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marsavian

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Unread post02 Dec 2019, 12:51

Does the Su-35 have the same G restriction with this auxiliary tank ?
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hornetfinn

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Unread post02 Dec 2019, 12:59

marsavian wrote:Does the Su-35 have the same G restriction with this auxiliary tank ?


I would think so, but don't know for sure. Maybe someone here has information about that.
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gta4

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Unread post02 Dec 2019, 17:40

milosh wrote:
Hm I don't know much about afterburners but I think how much fuel AB spend is still conected with thrust, F-35A with 8.2tons of fuel on max afterburner have 8.88N/kg thrust.

To match that T/W ratio, Su-27SM with 9.4tons of fuel (empty weight ~17tons) would need ~117kN engine thrust. Old AL-31F have 125kN and M1 version is 135kN (which is common engine in Russian SM) so with M1 engine Su-27SM need let we call it medium afterburner to match F-35A max afterburner T/W ratio. And when Su-27SM get AL-41 (Su-30SM already have them) it would need probable low afterburner.

Another question is how long you can use afterburner? For old Su-27 I read somewhere it is allow max 5min (constant AB) but for F-35 (I think B and C) I read some report where it is max 2min but not constant.

Okey Flanker is in big advantage over almost any fighter (expect F-14) because of engine gondolas which are make engine cooling easy but still afterburner duration is also important especially in combat when last thing pilot need it think about that too.


I think you are terrible at maths.

F-35 has 23% less thrust than Su-27 (192 KN vs 250 KN), however, its empty weight is also 23% less than a Su-27 (13 ton vs 17 ton). So they have almost the same T/W ratio if loaded with the same fuel fraction (fuel fraction = fuel weight / flying weight).

Given the SFC (specific fuel consumption) of modern turbo fan engines are all close to 1.9, it is easy to prove that when loaded with the same fuel fraction, Su-27 and F-35 have the same after burner duration and the same T/W ratio.

PS: AL-41F is not, and will never be fitted to Su-27 variants.

PS: static T/W ratio is significantly different from dynamic T/W ratio. It has been proven that F-35 has far better energy retention (at subsonic) than Su-27/35, so it is safe to assume F-35 has better dynamic T/W ratio:

viewtopic.php?f=55&t=52510
Last edited by gta4 on 02 Dec 2019, 18:02, edited 1 time in total.
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gta4

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Unread post02 Dec 2019, 17:48

Some evidence that may make Flanker fanboys heartbreaking:

1. F-35 has J-turn capability
viewtopic.php?f=22&t=53270

2. A J-turn capable fighter can easily out turn Flankers and Fulcrums:
viewtopic.php?f=37&t=54146
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gta4

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Unread post02 Dec 2019, 18:00

More evidence that may make Flanker fanboys heartbreaking:

1. In the eyes of Typhoon pilots, in WVR Flankers are easy preys while F-35s are tough opponents with funky maneuverability:
viewtopic.php?f=55&t=6094&start=2985

2. F-35's turn capability confirmed by test pilot:
https://www.youtube.com/watch?v=MJLoW1ClNE0
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gta4

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Unread post02 Dec 2019, 18:00

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swiss

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Unread post02 Dec 2019, 19:12

hornetfinn wrote:I've found at least this: https://issuu.com/duyenpham9989/docs/ai ... al_2017-04

On page 52 the Auxiliary Fuel Tank is described in the red box. That article looks pretty good and accurate (and has some great pictures of Flankers!).


Thanks Hornetfinn. Very interesting to read. It confirm also what spurts said in an other thread. The Su-35 larger wingspan is because of the wingtip pods (15.3m). Page 66.
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milosh

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Unread post02 Dec 2019, 21:19

gta4 wrote:
I think you are terrible at maths.


F-35 has 23% less thrust than Su-27 (192 KN vs 250 KN), however, its empty weight is also 23% less than a Su-27 (13 ton vs 17 ton). So they have almost the same T/W ratio if loaded with the same fuel fraction (fuel fraction = fuel weight / flying weight).

PS: AL-41F is not, and will never be fitted to Su-27 variants.


Nope you are terrible informed :D

https://www.ruaviation.com/news/2011/12/23/699/?h

Su-27SM because of stronger airframe is heavier (17tons) so it got engine upgrade also, there is AL-31F M1 in Su-27SM3. M1 have 135kN thrust, so spec. thust is 15.9N/kg

Btw similar spec. thrust Su-35 have (empty weight ~18tons, 284kN thrust).

Su-27SM3 will get AL-41 becuase oldest Su-27SM3 are 9years old and with AL-31F derivative service life of ~1200h olderst SM3 are will soon need new engine and AL-41 is only logical choice. It cost noticeable more but have much better service life, better thrust and lower fuel consumption. Btw oldest Su-30SM already getting AL-41, RuAF recieve first Su-30SM in 2011 but they clocked more hours two seaters longer mission durations plus training missions.

So when Su-27SM3 get AL-41, spec. thrust will be 16.7N/kg

About F-35A.

I really find nonsense comparing F-35A with any other fighter in WVR mode. F-35A in stealth configuration doesn't carry any wvr missiles, and demo flights it fly in stealth configuration without two pylons and two AIM-9X.

If you look what retired F-18 pilot said in talk show with Sprey, it is noticeable difference between naked plane and plane with just couple of empty pylons. Su-27SM3 or Su-35 naked or with two wvr missiles are same in fact wingtip missiles can even reduce drag.

This is why LM need to be pressure to develop Su-57 like wing pods for F-35. I wouldn't be surprise they in fact have smaller impact on plane performance then this:
https://static.businessinsider.com/imag ... /image.jpg

If there is some problem adding wing pod they could develop small belly pod (something like mini gun pod for B and C) which can carry two wvr missiles and DIRCM plus micro radar jammer.

Without stealth pods for wvr missiles it is really irrelevant what F-35A can show in demos when it fly in stealth configuration.
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juretrn

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Unread post02 Dec 2019, 22:25

But why would the aircraft with (highly likely) world's most advanced onboard EW need to carry another podded self-defense jammer? :wtf:
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wrightwing

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Unread post02 Dec 2019, 22:29

marsavian wrote:Does the Su-35 have the same G restriction with this auxiliary tank ?

Yes. When carrying full fuel all Flanker variants are limited to ~5 to 6G. It's not till they're below 60% fuel, when they have their full 9G envelope. That's why it's a silly comparison, using a fully fueled Flanker vs a fully fueled F-35 (which has no G/AoA/speed limits.)
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milosh

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Unread post02 Dec 2019, 22:46

juretrn wrote:But why would the aircraft with (highly likely) world's most advanced onboard EW need to carry another podded self-defense jammer? :wtf:


I don't know ask them:

download/file.php?id=18810&mode=view

last sentence in on that photo.

Btw mini pod could only be little bigger then pylon on which gun pod is mounted, forward and rearward it could have two DIRCM and in on sides wvr missiles, no space for any bigger jammer though.
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boogieman

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Unread post02 Dec 2019, 22:55

milosh wrote:
juretrn wrote:But why would the aircraft with (highly likely) world's most advanced onboard EW need to carry another podded self-defense jammer? :wtf:


I don't know ask them:

download/file.php?id=18810&mode=view

last sentence in on that photo.

Btw mini pod could only be little bigger then pylon on which gun pod is mounted, forward and rearward it could have two DIRCM and in on sides wvr missiles, no space for any bigger jammer though.


^Come on now, that's not an ASPJ pod, it's a multi-mission pod being advertised as able to carry a variety of payloads of which a jammer is just one :?
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marsavian

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Unread post02 Dec 2019, 23:14

milosh wrote:I really find nonsense comparing F-35A with any other fighter in WVR mode. F-35A in stealth configuration doesn't carry any wvr missiles, and demo flights it fly in stealth configuration without two pylons and two AIM-9X.


The F-35 is still stealthier than other aircraft with its tiny slanted ram-treated IR pylons and missiles (probably around 0.05 sq m RCS) and the Amraam itself can be fired WVR at only just a couple of miles out with a much higher pK. Strawman argument !
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