Forum: F-35 versus XYZ

Last edited by Pilotasso on May 05, 2012 - 10:18 PM; edited 1 time in total

The Eurofighter does not supercruise, it cruises supersonically(supercruise>mach 1.5), some sources say up to mach 1.3 with basic AA load and needs afterbuners to be pushed there first.

Also, the F-35 and Eurofighter fill in diferent roles. While the Euro is a fighter interceptor with a secondary AG role (role which development has been continuosly hampered by budget cuts) the F-35 is the other way around.

having said this if you compare both in AA, they complement this role differently . Lets see:

The Euro is more manuverable and faster, will carry longer range missiles to outreach and outgun its oponents, but The F-35 can choose to come closer to shoot (fewer rounds but each should count) or simply disapear, or both.

All in all I would choose the F-35 due to none of the above exposed. In these times you need a long range AG machine that can get to places unnoticed better than engage AA threats (though its quite powerfull if needed) because its much less likely to happen.
You can build a small force around the F-35, The Eurofighter needs a higher number of them and better support (from other fighters, AWACS, or tankers for example).

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That higher-numbered force is being pulled off by the RAF, RSAF, and Italy, and I believe them alone. As much as I like it, I'm not sure if the Tornado will be able to act as a workable counterpart for the Typhoon.

BDF wrote:

JW-

What's the reason the F-22 deflects the ailerons up during high G maneuvers? Reduce span loading and or twist and bending loads on the tips?

Since I did not work the Loads or Stability & Control tasks on that airplane, anything I say is just speculation. However, if the ailerons are up in high g maneuvers subsonically, it is probably for load alleviation (reduced span loading). The down load on the aileron dominates over the up load on the basic wing tip area.

At supersonic speeds, there may be a significant LE down twist to the wing tip area at 1g. Aileron up during a high g turn could eliminate that twist to make the wing more effective and reduce the required AoA. The down load on the aileron might be overcome by the increased up load on the tip due to twist.

The twist effects are determined by mach number, since the center of lift moves aft past transonic speeds. Farther aft, more twist per unit load.

Modern fly by wire systems give a Loads engineer the capability to move loads around to the most beneficial point - reduce load, increase control effectiveness, reduce drag, etc.

I believe the F-22 also uses afterburner to push it to supercruise speeds as did the Concorde because you have to pass through the transonic region as quickly as possible.

The issue is, how do you want to fight? Do you want to out-range and out-accelerate the other guy and play his game but play it better? Or do you want to change the game to a new game that it doesn't appear anyone else can play? If you play the other guy's game he can just upgrade engine, radar, and missiles to try and catch you. If you change the game he has to change too. Look at the MiG-1.42. It got cancelled. They went with the PAK FA which is now the T-50. The Russians are trying to get into the US game as best they can.

Supercruise is only really use full on short range intercepts, as soon as you have fly any significanct distance it is better to have the aircraft optimized for the transonic range like the F-35 is.

That's something I wonder about. Are the compromises in the F-22 to allow supercruise worth it?

Supercruise is very important from a all-aspect radar signature point of view (not only IR as commonly mentioned). The RCS of the plume caused by the afterburner is large, so large infact that all-aspect VLO signature is not attainable by any aircraft using afterburner (rear and side aspects are compromised).

@pseudonymous, you kind of missed the point of my comment. The only time you really need Supercruise is where you have to intercept an incomming missile or airplane in a hurry (over a short distance & a short duration). Outside of that mission profile the compromises you need to make an F-22 supercruise seriously hurts it fuel efficiency in the rest of its flight envelope. (Ie. Super Sonic Air inlets and turbo jet engines.)

Quote:

The only time you really need Supercruise...

I have to be a bit flippant here, after 23 years of using gobs of the taxpayer's JP4 to get super, and say in response to the following question...

Why supercruise?

Because you can... Cool

johnwill wrote:

Since I did not work the Loads or Stability & Control tasks on that airplane, anything I say is just speculation. However, if the ailerons are up in high g maneuvers subsonically, it is probably for load alleviation (reduced span loading). The down load on the aileron dominates over the up load on the basic wing tip area.

At supersonic speeds, there may be a significant LE down twist to the wing tip area at 1g. Aileron up during a high g turn could eliminate that twist to make the wing more effective and reduce the required AoA. The down load on the aileron might be overcome by the increased up load on the tip due to twist.

The twist effects are determined by mach number, since the center of lift moves aft past transonic speeds. Farther aft, more twist per unit load.

Modern fly by wire systems give a Loads engineer the capability to move loads around to the most beneficial point - reduce load, increase control effectiveness, reduce drag, etc.

Awesome, thanks for the insight. If you check out pics from the F-22 demos you can see both ailerons deflected up as I described so looks like I was on the right track.

Thanks!

alloycowboy wrote:

@pseudonymous, you kind of missed the point of my comment. The only time you really need Supercruise is where you have to intercept an incomming missile or airplane in a hurry (over a short distance & a short duration). Outside of that mission profile the compromises you need to make an F-22 supercruise seriously hurts it fuel efficiency in the rest of its flight envelope. (Ie. Super Sonic Air inlets and turbo jet engines.)

Its more than just running aircraft and missiles it also reduces the vulnerability and effectiveness of the supercruiser. About 5-6 years ago the USAF and LM released some charts showing the benefits of supercruise for loss and exchange rates against surface and airborne threats. These charts compared various mach and signature points but did not address altitude so I assume that altitude was the same for all the data points. To be succinct, going from M 0.8 to M 1.5 - while maintaining the same signature - doubled the survivability against surface based threats.

Comparing a supercruiser that has a signature advantage of one order magnitude better (but still ostensibly VLO) to a jet that's subsonic the survivability jumps to something like 3-4 times better. In the air to air missions the exchange ratio range from 7-8 times more effective for the same signature and interestingly something like 2-3 times more for a jet that's cruising at M 1.7 vs M 1.3. So there's much more than just running down air threats. The F-22 did loose some range compared to the original ATF spec and for strike missions supercruise appears to be reserved for ingress and egress to and from the target when transmitting through threat rings defending the target where defenses are at their densest (400 + 100nm NOT "mission 1" which is a OCA mission).

For the air to air missions fuel requirements are more stringet so range comes down but since thr F-22 burns slightly more than twice the burn rate at M 1.5 than M 0.8 it's quite conceivable that F-22s could come off tankers, go 150nm then supercruise for another 400-450nm then comeback at 150nm on a OCA sweep. While its not optimal and you do place some burden on support assets supercruise does provide decisive advantages which is undoubtedly why preliminary requirements for 6th gen efforts will include and undoubtedly expand a supercruise capability.

alloycowboy wrote:

@pseudonymous, you kind of missed the point of my comment. The only time you really need Supercruise is where you have to intercept an incomming missile or airplane in a hurry (over a short distance & a short duration). Outside of that mission profile the compromises you need to make an F-22 supercruise seriously hurts it fuel efficiency in the rest of its flight envelope. (Ie. Super Sonic Air inlets and turbo jet engines.)

One fundamental aspect of combat is mobility regardless of the situation. If a given plane can get places faster than their oponents, it has far more tactical options than the enemy.

pseudonymous wrote:

shingen wrote:

TV's only real use is for supersonic maneuvers. F-22 has it, Typhoon uses other means to get good supersonic maneverability.

No, it is the other way around, TV is near to useless for supersonic maneuvers.

Incorrect. The Raptor uses thrust vectoring to minimize trim drag, at supersonic speeds, by not having to use aerodynamic control surfaces. It also comes in handy at high altitudes, where control surfaces are less effective.

pseudonymous wrote:

Incorrect how?

Yes TV is used to reduce trim drag. That does not change the fact that is near to useless for supersonic maneuvers.
TV is being useful as a source of control at supersonic _and_ high altitude? Shocked

Are you kidding?

Please offer a source or technical reasoning for your comments. You are making inflammatory remarks without anything approaching justifications.

At high altitudes, low air density reduces the effectiveness of aerodynamic control surfaces.

Here's an argument....
In space, RCS (Reaction Control System) cold-gas thrusters are used to control a spacecraft's attitude and position, because aerodynamic control surfaces will be of little to no effectiveness. TVC offers a similar effect; control with thrust as opposed to with aerodynamic control surfaces. Therefore, it is more effective than only using elevators and ailerons to maneuver.

There is no arguement that higher speed with higher altitude is a good way to defeat surface to air missiles. That is the SR-71's bread and butter. That is all very well and good so long as you have the fuel to Super Cruise. But as soon as you start flying the majority of your mission in the "Transonic Speed Range" and are only using Super Sonic Dash speed when needed then your better off optimizing the aircrafts engines and air inlets for the transonic range. Which is what they did on the F-35.

I have heard that the F-22 only has enough fuel to Super Cruise for approximately 50 minutes. So that is 25 minutes out and back.

Forum: F-35 versus XYZ

F-35 vs Eurofighter?