I’ve always learned to distinguish stealth aircraft by their extremely angular and faceted surfaces, meant to reduce the possibility of a radar pulse being reflected back towards the receiver. However, several more modern stealth aircraft, such as the F-35 / Joint Strike Fighter, are full of beautiful (and aerodynamic) compound curves. How do they achieve a stealth effect with these surfaces? Do they just use an excessive amount of radar-absorbing materials and coatings?
I read somewhere that computer technology has advanced enough where modern stealth aircraft can be designed with smooth compound surfaces, rather than the faceted surface of the F117.
I don’t remember where I read it or when, so someone may be along shortly to correct me.
Faceted surfaces aren’t neccessary for stealth aircraft. The only reason the F117 has such a distinctive shape is because it’s far easier to model the reflections of a collection of polygons instead of curves. The F117 was designed in the 70s(?) so they had to limit their designs to what they could model.
Today, there’s enough processor power to model curved surfaces, and design those to avoid reflections. That lets us build higher performance, but still stealthy craft, like the F22.
Hal
That’s correct. The design was necessitated by the limitations of the mathematics that calculated radar reflections available to the designers.
Even by the time of the B2 bomber a few years later, there were formulas available to calculate a more aerodynamic yet still stealthy design.
It’s true that better computers (and better formulas too, I think) allowed the B2 to be curved instead of faceted, but another thing to consider, especially with something like the F22, is that the F117 was willing to trade off performance for more rader invisibility. The F22 is designed to be stealthy, but unlike the F117, stealth isn’t its primary design goal. The F117, despite its name, isn’t really a fighter, its a light bomber, and definately not a dogfighter.
Nobody ever mentions the F-19 - why is that? My understanding is that it was the next “stealth fighter” designed after the F-17, but it was the first to use curvaceous lines. Have I got my history wrong perhaps?
Also, and this is merely a quick explanation for those of you who might be reading this thread and not knowing how the principles of “radar avoidance” works…
Imagine you are standing in an empty football field at night and it’s absolutely pitch black. You have a spotlight which is really powerful. Now, imagine that 50 yards away, is a ninja dude totally dressed in black - real epic non reflective black as black clothing. With your spotlight, you might spot him, and you might not.
Now imagine that the ninja dude is hiding behind a 6ft high mirror which is absolutely perfectly polished with no dust on it. With your spotlight, if the mirror is pointed back at you, kaboom! You’re gonna see your own spotlight! That’s the equivalent of radar detection. However, if the ninja dude is smart, he’s gonna hold that mirror at 45 degrees in relation to yourself. Ain’t no way in hell your spotlight is ever gonna show up anything that way - the light beam is just gonna bounce off into space. Well, that’s the equivalent of “radar avoidance”.
And the ninja dude’s black clothing? That’s the equivalent of non reflective radar absorbing composites which these planes are made out of.
Still, there are tell tale traces of heat plumes and other giveaways.
That’s why I really dig the latest GPS unmanned drones which are flying around on behalf of the USA these days. They have GPS systems which transmit both their own position, and ALSO infra red TV pictures and light pictures of what they’re seeing. Back at base, in real time, computer systems crunch the numbers and work out precisely (to within 4 feet) the position of an enemy ANYTHING! It can be an artillery cannon, or a tank, or a platoon of men, or just plain ANYTHING. Even the heat plume emitting from a ventillator shaft in the middle of nowhere - signifying a massive underground headquarters bunker somewhere down there.
And then, without even needing to fly in a plane, either a Tomahawk can be sent in (probably a bit of overkill), or computer guided artillery can be fired (if you’re close enough).
Certainly, those unmanned drones are wicked beasts. And to my knowledge - they don’t advertise their presence in any way - neither heat wise, or radar wise, and they don’t send OUT radar signals either.
You can bet your bottom dollar a veritible flock of them are flying 24x7 over Iraq right now - and North Korea for that matter.
Boo Boo Foo: The F-19 never existed. It’s design was ‘leaked’ so as to throw the Russians (and any other country) off of the true shape of the F-117.
Is it just me, of was the YF-23 so much more stylish than the F-22 is?
Wouldn’t mind purchasing me one of these, though. MiG 1.42/1.44, designed as the answer to the F-22. The Russians claim that it performs as well in manuevering, speed, and payload, and is just as stealthy, for a bargain price of only $69,999,999.99 (plus tax and shipping). Haven’t heard about anyone actually buying one, though, if it is out of development yet. Or if the project was just scrapped altogether. The Russians aren’t exactly dumping boatloads of money into developing new superfighters these days.
IIRC, the F-19 was the product of speculation, just like the aurora is today. An F-19 computer game was released, complete with all kinds of specs about the supposed airplane, which lended a great deal of credibility to the rumours, but it turned out that the guys who designed the game based all of their info on the plane on the same rumours.
I don’t know how much of the F-19 was “leaked” or how much of it was just speculation looking at other stealth aircraft of the day, like the SR-71.
Thanks Skip! I was always a bit foggy on that one.
Stealth planes arent as hard to see as people think. During the last gulf war the Brit navy took great delight in reporting movements of US stealth planes to their owners.The planes have improved since then, but so has the radar.
If you can get your enemy to believe that resistance is futile, the battle is already won.
IIRC, diffdam, those planes were also flying in friendly airspace with external fuel tanks.
Stealth properties of our fighters/bombers do not make them completely invisible to radar detection…just harder.
Take a radar and draw a circle around it that indicates it detection area. Now string a line of radar such that their circles overlap and you now have a wall of radar that enemy planes cannot penetrate.
However, when you fly a stealth aircraft at that wall the circles shrink. That is…the effective range at which the plane can be detected is smaller. Think of your line of radars again and you’ll note witht he smaller circle of detection there are now holes to fly your plane through. The pilots will then weave their way through that wall and if done right no one should see them till it’s too late.
The Brits probably detected our stealth aircraft because they weren’t trying to be stealthy.
I remember a story about the development of the stealth fighter where the scientists had it parked out in a field and pointed a radar at it. They turned on the radar and were extremely disappointed at the radar reflection they were getting back. They really thought it would perform better. They then looked downrange at the plane and noticed a bird had landed on the plane. Once the bird took off the plane disappeared on the radar and the scientists were much happier.
Pilots report that the F-117 is a fine plane to fly although I seem to recall that the plane had been nicknamed the Wobbly Goblin early in its test flights because the not very aerodynamic shape made the plane difficult to fly. I think (but am not sure) that computers are needed to keep the plane flyable. A pilot without computer input to stabilize the plane would find it near impossible to control (same goes for the B-2 I think).
Some good answers here, but let me see if I can boil it down a bit more simply, with the help of Tom Clancy’s book “Fighter Wing” (non-fiction).
Basically, big angles are bad in terms of stealth. A radar pulse aimed at a metallic object composed of many 90 degree angles will reflect back and reveal an object easily. Planes like the old B-52 show up like the “broad side of a barn”. The big intake of the F-16’s engine shows up big too.
Curved surfaces help deflect radar pulses away so they don’t return to their point of origin. It is a combination of the plane’s geometry and radar absorbing materials that help make it stealthy. These materials are used extensively over parts of the plane that cannot be smoothed over much, like on the leading edges of the wings.
According to Clancy another area of concern for stealth is to disguise the exhaust temperature of the engine. The hotter it is, the easier to detect throuhg infrared. So they use specially shaped exhause valves and try to cool the gasses as much as possible before they depart the aircraft.
Cool stuff.
www.howstuffworks.com has a great thing on the B2 bomber. The website seems to be laggy right now, so sorry no linky.
F117’s don’t use external tanks.
Stealth doesn’t mean invisible. If you have an idea where they probably are and use a really powerful enough radar, you’ll see 'em. IIRC, thats what the Brits did.
Exactly. Stealth is an advantage, and given a big enough technological gap, completely invisible. However, that doesn’t mean that it’s impossible to find or shoot down. Remember, we lost an F-117 over Kosovo. (Slight hijack: Who wound up getting it?)
FWIW, I’ve been as close to an F-117 as a civilian can. When I say close, I mean CLOSE. Those things are impressive.
Also, something no one has seemed to mention yet, the F-117 and I believe the B-2 are coated with something that helps absorb radar signals. Design helps a lot to cut down radar cross section, but this helps even more.
I’m going off charts that I just remember, but don’t the stealth planes have an ideal cross section of about the size of a large seabird? A seagull or an albatross, perhaps?
Checking out “F-19” on Google, I saw a craft which looks like a rounder, smoother version of the Firefox plane from the Clint Eastood movie of the same name.
Colonel : “Soldier, what is your radar picking up there?”
Radar Operator: “Oh, nothing Sir. Just a flock of 15 seagulls at 25,000 FT going 500kts headed straight for our location.”
Colonel: “Carry on.”
I heard this version in a speech by an F-117 squadron commander, and don’t doubt it:
The F-19 designation had been reserved for the F-117 when it was made public. The F-117 name was a code, used for radio transmissions to avoid identifying the actual aircraft type, and was part of a tradition of extending the now-disused 100 series. The actual public unveiling was decided upon more quickly than the bureaucracy was prepared for; the F-117 designation became public knowledge; and it became easier to go with it.
There was a plastic model called “F-19 Stealth Fighter” which was based only on guesswork and resembles no real airplane.