Penetrating Counter Air / Next Generation Air Dominance

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
  • Author
  • Message
Offline

hkultala

Enthusiast

Enthusiast

  • Posts: 50
  • Joined: 11 Sep 2018, 08:02

Unread post12 Feb 2020, 21:14

marsavian wrote:
hkultala wrote:
disconnectedradical wrote:I don't think derivative is the way to go, F-35 airframe may have newer technology baseline but the base airframe won't have the kinematics that PCA will need, namely supercruise.


There is nothing wrong with F-35 airframe for supercruise. It would just need an engine with more powerful core, engine optimized for supercruise isntead of subsonic cruise and afterburning thrust; High bypass ratio(lots of bypass air) of F135 is nice for subsonic thrust and afterburnning thrust, but useless for supercruise.


Remember that F35's existing F135 has 28klb of dry thrust which is already broadly equivalent to F16C *wet* thrust. How much dry thrust would the F35 need to go supersonic, 30klb+ at least ? Typhoon supercruises easily with 27klb dry thrust.


Only about 22-23 klbs of that 28k is thrust from the core, and works at supersonic speeds. The rest 5-6 klbs comes from bypass air, which is only adding drag, not thrust, at supersonic speeds without afterburner. (because the air has to be slowed down to subsonic speed at the inlets, but the fan cannot accelerate it back to supersonic speed).

EJ200 engines of EF Typhoon has lower bypass ratio, giving them together about equal core thrust, and less drag from the bypass air. But EF Typhoon is a smaller plane, with less drag on clean configuration.

With an engine with core thrust of something like 25 klbs, F-35 would have no trouble of supercruising.
Offline

wrightwing

Elite 3K

Elite 3K

  • Posts: 3602
  • Joined: 23 Oct 2008, 15:22

Unread post12 Feb 2020, 22:18

zero-one wrote:
marsavian wrote:A clean sheet design or enlarged F-35 derivative with two engines is the way to go.


The F-35 is primarily designed for Strike and other ground operations not air to air. Yes it is capable on air to air, I would even say better than most but the design is tailored for A-G.

Modernizing the F-22 and changing all the obsolete parts plus upgrading existing systems is said to cost around 40 -50 billion. Heavily modifying the F-35 to be tailored for A-A will be far far more expensive, much better to have a clean sheet design.

Now if your clean sheet design needs to have the range requirements in excess of 1000 nmi radius and deep magazine, my question becomes can it be achieved within an airframe that has the size and weight which will still enable it to have the Kinematic performance on par or better than the Raptor?

Remember this thing needs to be able to hold its own against other VLO platforms, detection and tracking will be more difficult for all parties. The gun was kept on the Raptor and the F-35 in part as a fall back weapon of sorts. I think Kinematics should still be a part of PCA as a fall back as well.


I suspect the agility requirements will be lower priority to range, payload, speed, signature reduction, and situational awareness. By the time it enters service, the gun will likely be replaced by directed energy weapons with unlimited magazine capacity, as well as greater missile capacity.
Offline

wrightwing

Elite 3K

Elite 3K

  • Posts: 3602
  • Joined: 23 Oct 2008, 15:22

Unread post12 Feb 2020, 22:21

hkultala wrote:



Only about 22-23 klbs of that 28k is thrust from the core, and works at supersonic speeds. The rest 5-6 klbs comes from bypass air, which is only adding drag, not thrust, at supersonic speeds without afterburner. (because the air has to be slowed down to subsonic speed at the inlets, but the fan cannot accelerate it back to supersonic speed).

EJ200 engines of EF Typhoon has lower bypass ratio, giving them together about equal core thrust, and less drag from the bypass air. But EF Typhoon is a smaller plane, with less drag on clean configuration.

With an engine with core thrust of something like 25 klbs, F-35 would have no trouble of supercruising.

How are we defining supercruise? >M1.5 or >M1? With the current thrust, the F-35 is already capable of >M1 in dry thrust
Offline

hkultala

Enthusiast

Enthusiast

  • Posts: 50
  • Joined: 11 Sep 2018, 08:02

Unread post12 Feb 2020, 22:32

wrightwing wrote:
hkultala wrote:



Only about 22-23 klbs of that 28k is thrust from the core, and works at supersonic speeds. The rest 5-6 klbs comes from bypass air, which is only adding drag, not thrust, at supersonic speeds without afterburner. (because the air has to be slowed down to subsonic speed at the inlets, but the fan cannot accelerate it back to supersonic speed).

EJ200 engines of EF Typhoon has lower bypass ratio, giving them together about equal core thrust, and less drag from the bypass air. But EF Typhoon is a smaller plane, with less drag on clean configuration.

With an engine with core thrust of something like 25 klbs, F-35 would have no trouble of supercruising.

How are we defining supercruise? >M1.5 or >M1? With the current thrust, the F-35 is already capable of >M1 in dry thrust


I previously thought so also, but it does not.

The "dash" means that it accelerates to supersonic speed with an afterburner, then it turns afterburner off, starts to slowly decelerate, until it finally slows down to subsonic speed. But it cannot sustain flying at supersonic speed without afterburner, it will eventually fall back to subsonic at max military thrust.

But it can sustain flying at supersonic speed at very low afterburner level.
Offline

sprstdlyscottsmn

Elite 4K

Elite 4K

  • Posts: 4930
  • Joined: 10 Mar 2006, 01:24
  • Location: Nashua NH USA

Unread post12 Feb 2020, 23:26

The pilot report on that is AB up to 1.2M, then back to Mil, then it either slows down or the pilot goes 1-2 degrees nose down to hold 1.2M. It is darn close.
"Spurts"

-Pilot
-Aerospace Engineer
-Army Medic
-FMS Systems Engineer
-PFD Systems Engineer
-PATRIOT Systems Engineer
Offline

milosh

Elite 1K

Elite 1K

  • Posts: 1134
  • Joined: 27 Feb 2008, 23:40
  • Location: Serbia, Belgrade

Unread post13 Feb 2020, 00:29

wrightwing wrote:
How are we defining supercruise? >M1.5 or >M1? With the current thrust, the F-35 is already capable of >M1 in dry thrust


Above transonic range:
https://www.skybrary.aero/index.php/Fil ... _Range.png

so super cruise would be >M1.2 Mach but probable >M1.5 is what air forces consider as super cruise, because it is at least twice faster then subsonic cruise so difference is noticeable.
Offline

Corsair1963

Elite 5K

Elite 5K

  • Posts: 6896
  • Joined: 19 Dec 2005, 04:14

Unread post13 Feb 2020, 02:49

wrightwing wrote:
How are we defining supercruise? >M1.5 or >M1? With the current thrust, the F-35 is already capable of >M1 in dry thrust



Clearly, anything over Mach 1 on Military Power (sustained) would have to be considered "Supercruise".
Offline

quicksilver

Elite 3K

Elite 3K

  • Posts: 3136
  • Joined: 16 Feb 2011, 01:30

Unread post13 Feb 2020, 03:00

sprstdlyscottsmn wrote:The pilot report on that is AB up to 1.2M, then back to Mil, then it either slows down or the pilot goes 1-2 degrees nose down to hold 1.2M. It is darn close.


x2

This description too —

“I previously thought so also, but it does not.

The "dash" means that it accelerates to supersonic speed with an afterburner, then it turns afterburner off, starts to slowly decelerate, until it finally slows down to subsonic speed. But it cannot sustain flying at supersonic speed without afterburner, it will eventually fall back to subsonic at max military thrust.

But it can sustain flying at supersonic speed at very low afterburner level.“
Offline

Corsair1963

Elite 5K

Elite 5K

  • Posts: 6896
  • Joined: 19 Dec 2005, 04:14

Unread post13 Feb 2020, 04:02

We have just one old quote about the F-35's ability to "supercruise". Which, was very vague and was subject to considerable interpretation.


Much has changed since then.....So, I would be "cautious" about drawing any serious conclusions one way or another.


"IMHO"
Offline

wrightwing

Elite 3K

Elite 3K

  • Posts: 3602
  • Joined: 23 Oct 2008, 15:22

Unread post13 Feb 2020, 16:16

Corsair1963 wrote:We have just one old quote about the F-35's ability to "supercruise". Which, was very vague and was subject to considerable interpretation.


Much has changed since then.....So, I would be "cautious" about drawing any serious conclusions one way or another.


"IMHO"

Actually there have been several. One said 150nm dash at M1.2 in military. The others were more vague.
Offline

quicksilver

Elite 3K

Elite 3K

  • Posts: 3136
  • Joined: 16 Feb 2011, 01:30

Unread post13 Feb 2020, 16:49

The jet does not sustain supersonic speed in mil thrust in level flight at any altitude. Period.

And, don’t trot out the Steve O’Bryan second-hand anecdote from 8 years ago. He was wrong or misunderstood by the reporter (I vote for the latter). If you want a public pronouncement from someone who flew the jet, find the whole Hank Griffiths quote on the subject; Griffiths was CO of the test squadron at EDW.

FWIW, not one of the many F-35 guys I know and have spoken with about the topic — very specifically — have ever suggested otherwise.

This subject is like one of those gag birthday candles that you can’t ever blow out...
Offline

disconnectedradical

Forum Veteran

Forum Veteran

  • Posts: 907
  • Joined: 31 Dec 2010, 00:44
  • Location: San Antonio, TX

Unread post13 Feb 2020, 19:41

zero-one wrote:The F-35 is primarily designed for Strike and other ground operations not air to air. Yes it is capable on air to air, I would even say better than most but the design is tailored for A-G.

Modernizing the F-22 and changing all the obsolete parts plus upgrading existing systems is said to cost around 40 -50 billion. Heavily modifying the F-35 to be tailored for A-A will be far far more expensive, much better to have a clean sheet design.

Now if your clean sheet design needs to have the range requirements in excess of 1000 nmi radius and deep magazine, my question becomes can it be achieved within an airframe that has the size and weight which will still enable it to have the Kinematic performance on par or better than the Raptor?

Remember this thing needs to be able to hold its own against other VLO platforms, detection and tracking will be more difficult for all parties. The gun was kept on the Raptor and the F-35 in part as a fall back weapon of sorts. I think Kinematics should still be a part of PCA as a fall back as well.


It's $50 billion just to restart production and build another 194 F-22A, not even an upgraded version. Super F-22 will require more engineering work and be even more expensive.

A clean sheet that takes advantage of new materials and aerodynamics advances since F-22 should be able to roughly match the performance while also giving better range. For example F-22 composites is only 25%, while F-35 is 35% and PCA can be higher than that. Also clean sheet can be designed from the start to take advantage of ADVENT engines.

To save weight they can probably lower g to 7.5g, since unless you're at about 10,000 ft or below no one is sustaining 9g. Hornet does 7.5g and there aren't many complaints about its turning, mainly the lack of acceleration. But with immense power PCA can just go vertical instead of just doing horizontal turning.
Offline

hkultala

Enthusiast

Enthusiast

  • Posts: 50
  • Joined: 11 Sep 2018, 08:02

Unread post14 Feb 2020, 11:47

zero-one wrote:
marsavian wrote:A clean sheet design or enlarged F-35 derivative with two engines is the way to go.


The F-35 is primarily designed for Strike and other ground operations not air to air.


No, it's not. It's equally-designed for air-to-air and air-to ground.

About the only feature in F-35 which is more made to air-to-ground than air-to-air are the weapons bays, which are made deep enough to handle those 2000lb bombs, but which initially cannot carry 3 missiles each (later they will, first 3 AMRAAMs each and them 6 pegerines each).

But when those new missile racks and Pegerines appear and it then carries for example 2 Meteors, 2 AMRAAMS and 4 Pegerines internally, I see no big inefficiences with the bays for air-to-air use.

Modernizing the F-22 and changing all the obsolete parts plus upgrading existing systems is said to cost around 40 -50 billion. Heavily modifying the F-35 to be tailored for A-A will be far far more expensive, much better to have a clean sheet design.


No amount of modernizing of F-22 will bring it's range to even close to what is required for PCA.
Offline

sprstdlyscottsmn

Elite 4K

Elite 4K

  • Posts: 4930
  • Joined: 10 Mar 2006, 01:24
  • Location: Nashua NH USA

Unread post14 Feb 2020, 16:17

hkultala wrote:
No, it's not. It's equally-designed for air-to-air and air-to ground.

About the only feature in F-35 which is more made to air-to-ground than air-to-air are the weapons bays,

And the aspect that shows it is still designed for air to air is that it is the only plane on earth cleared for 9G with two 2,000lb munitions. They wanted to make sure it could be a dominant A-A plane even on a bombing mission.
"Spurts"

-Pilot
-Aerospace Engineer
-Army Medic
-FMS Systems Engineer
-PFD Systems Engineer
-PATRIOT Systems Engineer
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2549
  • Joined: 12 Jun 2016, 17:36

Unread post14 Feb 2020, 17:33

sprstdlyscottsmn wrote:
hkultala wrote:
No, it's not. It's equally-designed for air-to-air and air-to ground.

About the only feature in F-35 which is more made to air-to-ground than air-to-air are the weapons bays,

And the aspect that shows it is still designed for air to air is that it is the only plane on earth cleared for 9G with two 2,000lb munitions. They wanted to make sure it could be a dominant A-A plane even on a bombing mission.


I'll add to Spurts' comment... Gums told me that only the very beginning of an air-to-air fight in a Viper was at 9g, maybe the first 2-4 seconds, for like 90° of turn, occasionally (rarely?) up to 180° of turn. The vast majority of the fight was like at 5-6g. So how much advantage do you really get from being able to honk it over at 9g? Well, you are trying to gain as much of an initial angles advantage as you can right off the bat... so by specifying that 9g capability, even if it could not be sustained at most altitudes (a bit of conjecture on my part), tells me the Air Force was trying to wring as much air-to-air performance as it could out of the airframe. In light of QS recent comments in an F-35 thread, with the advent of all-aspect HOBS missiles, the fight has shifted to whoever gets the nose on first, wins. So that initial 9g ability is important at the higher speeds.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
PreviousNext

Return to Modern Military Aircraft

Who is online

Users browsing this forum: Bing [Bot] and 33 guests