Forum: General F-22A Raptor forum

Chines are an extension of the body and LERX are an extension of the wing. To tell the two apart look at the body shape at the point of "attachment".

"What is the 5th generation's aerodynamic leap?"

6) internal weapons storage on a light fighter
7) thrust

Chines seem to provide the same benefit as blended wing body/LERX's with less area

You can go canard delta

With both the F-15 and F-16 flying without one wing, is the "loss of control" for the tailless really going to be an issue?

and possibly early directed energy

or unmanned (either mission duration or "G loading" or both)

Well, combining modern aerodynamics with stealth technology without sacrifacing performance and maneuverability.

what was the logic behind making the Super Hornet's LERX's huge?

I personally see the F-22's chines as having way more to do with RCS reduction than anything else. I don't see them providing enough of a flat upper surface needed for effective vortice generation... The bulk of the F-22's vortices being generated by the LERX's (however small they may be) and the wings' leading edges:

Assuming there's an aerodynamic advantage compared to an unstable wing-tail???

(Please let's not open THAT can of worms again.)

I also fail to see any advantages that would be afforded by unmanned fighters with regards to G loading. I mean, the F-22 is rated at +9.5/-3.5 G's (yeah, it can pull more, but only on an intermittent basis). Modern G suits like the Libelle and CE/ATAGS allow the fitter pilots to sustain 9 G's, and tolerate an excess of 12 G's w/o G-LOC (in the short term). That's right up at the G limits of modern airframes. How will making a fighter unmanned raise these airframe limits?

I think there are two benefits of the SH's fatter LERX's, at least compared to the ones on the legacy Hornet. (This is just my , mind you.)

1. As I understand it, the legacy Hornet was a somewhat stable design, so increasing the LERX area may have served to move the plane's center of lift forward, thereby reducing inherent stability and (potentially) increasing maneuverability.

2. It's well-known that earlier (legacy) Hornets had problems with premature wear/cracking of the vertical tails, due to the vortices hitting them and causing violent buffeting. By comparison the vortices produced by the SH's wider LERX's terminate well outward the vertical tails.

The point is, a tailless aircraft with no rudder(s) will not be controllable without TVC. No engine, no TVC.

Not so. The GD/MD A-12 had no tail or rudder surfaces and no TVC. Had it ever flown, it would have been controllable.

uot;]and possibly early directed energy

or unmanned (either mission duration or "G loading" or both)

Really? I would have thought no chines would have made for a better RCS.

Off the top of my head, isn’t it the limit of the pilot that sets the airframe g-load right now? We could stress airframes for more g (for more cost) if we wanted, that’s my understanding anyway.

Good to know.

Just out of curiosity, what does the UN have to do with US weapons and does it really matter if a laser fries a kid 200 miles away or a conventional bomb turns one to dust 20 miles away? dead is dead right? I fail to see what the distance at which it happens really matters. A targeting glitch on a conventional weapon kills the wrong guy at 20 miles and the other does it at 200 miles. So what!

Well would not the fact an unmanned fighter could *sustain* these 12G limits indefinitely versus short term be a huge advantage? And if they were to make new a/c unmanned, isn't there literally thousands of pounds of man and related equipment in an a/c necessary to have a human in it that could now be replaced with thousands of pounds of materials to greatly strengthen the air frame of the new unmanned a/c making it's G limits potentially far greater then 12Gs?

The main point of chines on VLO airframes is to avoid a cylindrical fuselage... It's the same reason why vertical tails are shunned: to avoid "presenting" vertical surfaces while in level flight:

(Yes, in my world, radar waves a a nice shade of magenta.)

Wasn't there talk around here a while back about fighters needing to be "re-winged" due to overstress? Older F-15's that are/were literally falling apart? And then there's the Navy's imposed 7.5 G limit on its fighters. That limit is not for the pilots' sake.

Hard maneuvering is just as stressful on airframes as it is on pilots.

Oh good!... That made sense to you?

The F-22 without chines wouldn't have a rounded fuselage anyway.

Yes it is, and you bring up some good points. However, if technology can only keep a pilot awake at 9g, why bother spending money on making planes take more than 9g? There’s no reason for it, and that could possibly explain current g limits.

I think what really kills stressing planes for high g is that they would bleed so much energy making such hard maneuvers that there would not be much point to them.

I hope I don’t come across as being that ignorant. lol

Required g for fighters are limited by human capability, period. They are then designed to be as light as possible and still withstand the short term and long term effects of the resulting loads.

Didn't I read somewhere the AIM-120 can turn at 55g?

Older F-15s (and F-16s and F-18s) are "falling apart" not because they are "overstressed", but because they are being used longer and more severely than the original design. Energy loss at high g is a valid concern and may be the limiting factor in future designs.

Didn't I read somewhere the AIM-120 can turn at 55g?

Missiles have a service life measured in SECONDS, not decades. Apples and oranges. It also stands to reason that a comparatively small, monolithic cylindrical form with SMALL fins would tolerate higher G and aerodynamic loads than a fighter with much larger flight/control surfaces.

A ten-fold difference is a huge deal. IMO, people living 20 miles from a hot zone are more likely to be wary of the dangers than those living 200 miles away (or even 300 miles, see below). There's also the whole "instant kill" nature of it all.

I still do NOT see the big deal. What diff does it make if someone is more*wary* of it? If the wrong people get killed they are still dead regardless of how far away it happened. I targeting glitch can happen with any system.

BTW, that 200 mile figure was just a wild guess on my part, taking into account the Earth's curvature. Turns out I wasn't far off. Using a bit of basic trig, 200 miles would be roughly the max. distance attainable by a laser (mis)fired from approx. 26,500 ft. of altitude (not taking terrain/topography into consideration). From 50,000 ft., that distance grows to about 270 miles. At 60,000 ft., it's ~300 miles.

Again the distance away it happens I just don't see what it matters.



This would assume that modern fighters aren't already built for maximum performance/rigidity. I seriously doubt that's the case given the service lifetime that's expected of them.

[color=darkblue]Well yea, and that's based on the materials that was used when they were built which most are what, 20+ years old? As well as knowing they had limits due to a human flying them so no earthly reason to make them any stronger right? So there was absolutelu no need or use to make them withstand anything more then what they do now.

Also, I have no doubt that the whole human-machine interface (including controls, displays, seat, O2, environmental, etc.) does weigh quite a bit. But exactly what percentage of an F-22's combat weight is attributable to pilot essentials? 3%? 4%? 5% tops? (Again IMO) it's more likely that the extra space would go towards internal fuel (assuming they wouldn't just grasp the weight savings altogether).

One targeting glitch, and that laser may very well end up frying a 6 year old riding his/her bicycle over 200 miles away from the combat theater.