/sci/ - Science & Math

[Anonymous No.3883381]

Aeronautical engineering general.

[Anonymous No.3883385]

>no jobs unless you're really good general

[Anonymous No.3883389]

>>3883385

[Anonymous No.3883396]

well i think this thred is over now

[Anonymous No.3883400]

>>3883385
It cant be that bad can it?

[Anonymous No.3883413]

why has nobody yet implemented the mach pulse supercharger for the turbine engine?
wouldn't a series of louvers be more efficient than a single flap at the trailing edge of a wing?
isn't there a way to make use of the heat produced from an engine instead of just wasting it away behind the aircraft?

[Anonymous No.3883415]

>>3883385
>Truth.

Here is a homeless guy who holds two master's degrees from non-shit unis.

http://www.youtube.com/watch?v=8eNPAH46oI8

One Master's is in Physics, the other in EE. He worked as an Aerospace Engineer and got laid off.

Times are tough.
>And it's not just because he is a nigger. This is everybody.

[Anonymous No.3883427]

>>3883415

He's been out of work for 17 years, I doubt anyone would hire him, I bet he's never even used a CAD program

[Anonymous No.3883449]

>>3883413
What can that heat be used for, other than afterburn? Perhaps some sort of advanced thrust vectoring?

The harrier has various outlets around the engine to disperse the thrust and to make VTOL possible. Maybe a similar system can be employed, but to improve maneuverability.

If the modified F119 engine in the F35 was used like this, it would have more than enough power with 40,000lb's of thrust each.

[Anonymous No.3883457]

>>3883413
On board Desalination

[Anonymous No.3883470]

>>3883449
Here is a diagram of the Harrier's propulsion system.

Perhaps one or two nozzles up front or on a wing, and that thing would high-alpha like a mother fucker.

[Anonymous No.3883477]

>>3883470
Forgot photo.

But if that was coupled with the thrust vectoring of the f-22, it could probably cobra 10x better than any russian aircraft.

[Anonymous No.3883480]

>>3883477
forgot photo again

[Anonymous No.3883483]

>>3883449
Good thinking.

I'm not sure how that would impact aerodynamics, however.

VTOL could be possible too.

[Anonymous No.3883485]

how about using the wasted energy to reform the skin on the wings or fuselage? plenty of excess heat when you're going full on afterburner.

[Anonymous No.3883493]

i work in aeronautical engineering!!

at the lowest level that is,

>r22 50 hour inspections all day errday
>oil changan
>wire lockan
>ground runnan

feels... not too bad, man

[Anonymous No.3883495]

>>3883485
>reform the skin on the wings or fuselage

What do you mean?

[Anonymous No.3883497]

Sup guys. Just a /k/ommando passing through. I made this for /k/ to demonstrate lifting line theory's applicability to fighter maneuverability and figured it was relevant here (ignore the mistakes I made during the "yada yada" here; I was in a rush, and I corrected them before I moved on to part two).

[Anonymous No.3883504]

>>3883497
>Realize using "L" for lift is confusing since I used it for span too
>Realize I totally fucked up the substitution on the last page
>Completely jump tracks halfway through my derivation
Sorry it's so sloppy. I need to put it all in a tidy, correct form and post a new thread on /k/ about it.

[Anonymous No.3883508]

>>3883493
Really? Cool!

[Anonymous No.3883513]

>>3883497
>>3883504
i should go to /k/ more often

[Anonymous No.3883519]

>>3883504
...Shit. Looks like I kinda fucked up my FBD too.

Well, at least the given equations on the first page and the result equations on the second page are right, even if the in-between is terribad. They gave a sustained turn rate of 17.4 degrees per second for an F-35A at mach 0.6 at sea level, which is a reasonably realistic value. I totally had to guess at the Oswald factor though; I hope 0.9 is close. I need to find and evaluate some real-world data for some comparable jet to be sure.

Better yet... if I find the data, would anyone else ITT like to test their abilities and take a whack at it?

[Anonymous No.3883522]

>>3883495
afterburner heat exchanger used to stretch skin into a less draggy shape.
no afterburner, no slippery shape.

[Anonymous No.3883525]

>>3883513
no you should not

[Anonymous No.3883532]

>>3883522
Are there any non-exotic materials that have that trait?

I would imagine a ducting system similar to that in >>3883449 would need to be used. Good idea.

[Anonymous No.3883535]

>>3883519
I haven't exactly delved into that realm of aeronautics yet. I would love to, just haven't.

[Visiting /k/ommando No.3883540]

>>3883413
>isn't there a way to make use of the heat produced from an engine instead of just wasting it away behind the aircraft?
I know the Spitfire did, such that the radiators under the wing actually produced their own thrust.
http://en.wikipedia.org/wiki/Meredith_Effect
I wouldn't be surprised if modern air-cooled aircraft with carefully-designed cowlings benefited in a similar fashion, as well. In theory, all it'd take is the right ratio of inlet to outlet areas and streamlined internal ducting.

[Anonymous No.3883553]

Excuse my rudimentary knowledge of aerodynamics, but if you placed a radiator or hot engine emissions on the top of the wing, it would reduce the density of the surrounding air, thereby allowing an even faster circulation of air and thus, increased thrust?

[Visiting /k/ommando No.3883555]

>>3883535
Well, all the equations you need are listed in my first image. All you need to do is put it all together. =P
>>3883513
/k/ is shit right now; that's why I'm here. But yeah, if you're into this sort of thing, intellectual discussion does come up every once in a while. I bet you guys would've had a field day with our pogo thread a couple days ago...

[Anonymous No.3883556]

>>3883553
Lift from the airfoil, not thrust. My bad.

[Visiting /k/ommando No.3883559]

>>3883553
>>3883556
No. Density is nearly as critical as velocity when it comes to fluid-dynamic forces.

[Lunatic !!h/HxpkvWDAR No.3883564]

>>3883522
nitinol is about as exotic as any alloy that'd be on a fighter jet.

Problem is response time(doesn't turn on fast enough, stays on too long) and afterburners usually aren't run for very long. Interesting idea, though. One might be able to use some waste heat to power the electronics.

[Anonymous No.3883569]

>>3883559
Correct me if I'm wrong but airfoils function by having a faster flow of air above the wing than below it, right? The density of the air below the wing would remain the same, but the air above the wing would be less dense, creating even more lift?

I am sure something is fundamentally wrong with this, just curious.

[Anonymous No.3883574]

>>3883569
I mean the pressure differential (in my mind at least) would be even greater.

[Visiting /k/ommando No.3883586]

>>3883477
The Cobra maneuver, post-stall maneuvering, and thrust-vectoring in general are all airshow gimmicks with no combat relevance.

Nothing against the F-22, of course... but I'm just telling it like it is.
Don't have to take it from me, though:
http://www.youtube.com/watch?gl=GB&hl=en-GB&v=WKEa-R37PeU

[Anonymous No.3883593]

>>3883586
I know. Lol. Just saying.

Does thrust vectoring help high altitude performance? Control surfaces wouldn't have as much air to work with, so directing the thrust must help in those circumstances.

[Visiting /k/ommando No.3883602]

>>3883569
>Correct me if I'm wrong but airfoils function by having a faster flow of air above the wing than below it, right?
While true, the common conception that airfoil lift is caused by the Bernoulli effect is somewhat fallacious. Ultimately, the best way to look at how a wing produces lift is that "wing deflects air down, deflected air pushes back against wing."

And since we don't have any sort of physical barrier to prevent the heated air from expanding, pressure will NOT increase significantly due to heating. Volume will, though, and this is the nature of the aforementioned Merideth effect.

[Anonymous No.3883619]

>>3883602
>the common conception that airfoil lift is caused by the Bernoulli effect is somewhat fallacious
As you can tell, my education is at best sub-par.

Very interesting stuff. Are there any books you would recommend?

[Anonymous No.3883646]

> While true, the common conception that airfoil lift is caused by the Bernoulli effect is somewhat fallacious.

The Bernoulli effect creates lift, but it isn't the only cause. However, lift created by the Bernoulli effect results in less drag than the same amount of lift caused purely by deflection. An airliner in level flight generates most of its lift by the Bernoulli effect. For a jet fighter, which may have roughly the same amount of thrust as an airliner but a small fraction of the mass, the Bernoulli effect is a lot less important.

[Visiting /k/ommando No.3883654]

>>3883593
Thrust decreases substantially with altitude as well. Keep that in mind.

If you're using rocket-propelled attitude thrusters instead, such as on the X-15 or NF-104, then it's a different story. But for the most part, airplanes will run out of engine before they run out of control authority.

[Anonymous No.3883658]

>aeronautical engineering
>not the easiest discipline

[Visiting /k/ommando No.3883672]

>>3883619
I figured most my stuff out from wikipedia, other internet browsing and personal experience (private pilot and avid modeller). I actually have no formal education in aeronautical engineering, but I just started my first fluid mechanics course.

Also, this book was helpful: http://books.google.com/books?id=kaqvC4e_EKcC&pg=PA130&lpg=PA130&dq=introduction+to+airc
raft+maneuvering&source=bl&ots=BJA2zbX2Xv&sig=-o5y_h5H8lBc_IA36gRF6c-5QOM&hl=en&
ei=etKITfnkHJTqgQetp8S3DQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CB8Q6AEwAg
#v=onepage&q=introduction%20to%20aircraft%20maneuvering&f=false

[Anonymous No.3883681]

>>3883672
Thanks. I'll shop around for a used version. Lol.

[Lunatic !!h/HxpkvWDAR No.3883682]

>>3883646
>>3883646
>>3883646
NOPE
http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

[Visiting /k/ommando No.3883695]

>>3883646
Well...
Obviously, Bernoulli's law doesn't simply cease to be true when looking at wing behavior. That's not what I'm saying. And you COULD analyze it using Bernoulli's law. But the whole Bernoulli lift notion is based on the so-called "equal-times fallacy" - that it takes the air going over the top of the wing the same time to transit as the bottom. This is simply not true. More properly, as the air is accelerated - circulated - around the airfoil's profile, its pressure against the convex surface decreases. Of course, in accordance with Bernoulli, this (pressure) energy is transferred to local velocity, but really I view that as a peripheral effect.

[Anonymous No.3883723]

>>3883658
how so?

[Anonymous No.3883728]

>>3883723

baby-tier maths

[Anonymous No.3883744]

>>3883728
so?

[Visiting /k/ommando No.3883746]

AH HAH

F-15 sustained turn data!

(The F-15's *kinda* similar to an F-35.... right?)

Other info needed:
Thrust: 23,950 lbf (x2)
Span: 41.8 ft (13.05 m)
Area: 608 ft^2 (56.5 m^2)
Mass: See chart
Zero-lift drag coefficient: I dunno, 0.022ish?
Sea--level air density: 1.225 kg/m^3 (I don't feel like converting anymore)

So, who thinks they're up for some simple applied algebra? Find the "e."

[Anonymous No.3883749]

>>3883682

really the only thing wrong about the theory is the idea that the particles must (for some reason) meet up together at the rear of the airfoil. the idea that the particles going over are faster is true, as is the fact that those faster particles cause a lower pressure above the airfoil section.

for the guy who suggested mounting something above the wing, thats never a good idea. the upper area of the wing should be as aerodynamic as possible, unless youre relying on massive amounts of thrust to brute force your way into the air (at which point youre not creating lift so much as being a projectile)

[Visiting /k/ommando No.3883762]

>>3883749
>the upper area of the wing should be as aerodynamic as possible, unless youre relying on massive amounts of thrust to brute force your way into the air
Tell that to Honda.

[Anonymous No.3883778]

>>3883749
The idea was to integrate some sort of radiator/heat conductive material into the wing surface, no actually mount the device to the wing. I understand what you mean though.

>>3883746
In the video you posted, the F15 has a sustained turning rate of something like 14 degrees, and the Raptor 28. I would place the F35 at maybe 18.

[Visiting /k/ommando No.3883798]

>>3883778
Well, 18 is what I got...
But what I'm really looking for right now is a realistic Oswald efficiency factor for fighter jets. I'm starting to think that this data might not work for sea level though, since the F-15 appears to hit structural limit and then mach 1 at sea level before drag becomes the limiting factor (and the equation changes dramatically at supersonic speeds, so that doesn't really help me at all).

I guess I need to find a thrust-altitude chart for the F-100-PW-100 and try some other altitude instead...

[Anonymous No.3883803]

>>3883415
if hes so smart why is he black?

[Anonymous No.3883806]

>2011
>using lbf

Jesus Christ America.

[Anonymous No.3883837]

>>3883803

[Visiting /k/ommando No.3883846]

>>3883806
>Implying that graph is from 2011

[Anonymous No.3883862]

Here's an interesting read. Make sure you read through the whole project.

[Anonymous No.3883866]

>>3883862
http://www.aerospaceweb.org/design/ucav/main.shtml

[Anonymous No.3883897]

>>3883672
>private pilot
What do you fly?

[Visiting /k/ommando No.3883903]

Alright, I'm off to bed. Little bummed I couldn't find some data suitable for finding an accurate Oswald number.
>>3883866
I think I'll check that out in detail when I have time. They've even given themselves a minimum Ps spec; should be interesting.

[Visiting /k/ommando No.3883905]

>>3883897
These, mostly.

Anyways, bedtime. For real now. I might check this thread in the morning if it's still here.

[Anonymous No.3883952]

>>3883457
Desalination of what?

[Anonymous No.3883959]

>F-22 became a 100 billion project and production
>all grounded due to issues

why.jpeg

[Anonymous No.3885411]

>>3883959
It was actually a $66.5 billion project.

[Anonymous No.3885460]

>>3885411
Touche.

[Anonymous No.3885504]

fuckers with your HIGH TECH planes

how about some real engineerin for fucks sake

[Anonymous No.3885518]

>>3885504
yeah fuck the japs

[Anonymous No.3885537]

>>3885518
>>3885504
Suddenly, old people.

[Visiting /k/ommando No.3885538]

>>3885504
The Spitfire has already been mentioned, in case you hadn't noticed.

Anyways, I'm back. Anyone care for further discussion?

[Anonymous No.3885544]

This thread is going in all the wrong directions.

Let's talk about methods to improve the handling characteristics of future fighting jets?

[Anonymous No.3885550]

>>3885538
The F35 is beautiful.

[Anonymous No.3885561]

>>3885538
What kinds of things to do expect in 6th generation fighter jets? Other than UCAV capabilities, of course. Construction wise.

[Visiting /k/ommando No.3885569]

>>3885544
>Let's talk about methods to improve the handling characteristics of future fighting jets?
Okay...
I, for one, feel that maneuverability is "good enough" now, and that future fighters should shift their focus to other issues such as armament, range, low-observability, etc., but if you want to discuss what makes a fighter maneuver well, I'm down for that.

[Anonymous No.3885592]

>>3885569
What makes the F22 handle so well?

I was reading that these days planes are being developed that are very unstable, but with advanced computers, they an harness that inherent instability and create maneuverability?

[Anonymous No.3885602]

How well do you guys know your Cold-war interceptors?

[Anonymous No.3885608]

>>3885592
Its hard to maneuver when your plane is trying to right itself at every single moment.

Modern jets more or less can't fly without computers taking care of millions of calculations every second. But that is exactly what makes them so maneuverable..
Thurs vectoring helps too.

[Visiting /k/ommando No.3885647]

>>3885561
Personally, I don't think air-to-air UCAVs will be ready by the time Gen-6 comes around. My uncle works for General Atomics Aeronautics, building and repairing prototypes out at the Apple Valley facility, and by the sound of things, UAVs don't stand a chance against manned aircraft in ATA combat, and won't for a LOOOONG time. With the Sea Avenger, which is intended to operate in contested airspace, they aren't even bothering with an RWR, since they acknowledge that if the drone is pinpointed by a radar threat, they're fucked anyways.

Besides, the issues of pilots' physiological limitations limiting the performance of a fighter is highly overrated; notice that the F-15C, the backbone of the USAF's air superiority fleet, is operationally limited to only 5 Gs now due to fatigue, yet it STILL continues to kick ass and take names.

[Anonymous No.3885652]

>>3885569

What the hell do they use as rocket propellent? The only rocket I've seen making shock diamonds like that would be from XCOR, But I doubt they use liquid fueled rockets.
http://www.youtube.com/watch?v=mbtvFIEBJdA&NR=1

[Anonymous No.3885679]

>>3885652
Solid fuel can do that too, you just need faster-than-sound exhaust.

[Anonymous No.3885697]

>>3885679

What solid propellent doesn't produce smoke?

[Anonymous No.3885717]

>>3885697
If the gas is moving faster than sound, I would imagine you wouldn't see any gas from that angle.

[Anonymous No.3885718]

>>3885717
smoke from that angle*

[Anonymous No.3885727]

>>3885718

That's the best angle from the cockpit, you can clearly see far behind the rocket

[Anonymous No.3885752]

>>3885727
It's a mystery. I have no idea.

Maybe they're just really clean burning.

[Visiting /k/ommando No.3885755]

>>3885592
>What makes the F22 handle so well?
A lot of things. Its wing area is enormous, which helps reduce the lift coefficients (and thus, induced drag) required for any given maneuver, with a moderate sacrifice in zero-lift drag (which is why the F-22 is somewhat slower at the top-end than an F-15). This, combined with its astronomical thrust:weight ratio, helps it achieve unprecedented sustained maneuverability. Furthermore, the fact that the wing uses leading edge slats (unlike the F-15) permits a much higher Cl-max (peak lift coefficient at stall AOA), allowing incredible instantaneous maneuverability as well. Aiding both of these are the F-22's usage of relaxed stability, shifting some load onto the stabilators, so that they can help produce lift and pull the jet around a turn as well. The thrust vectoring, while not absolutely necessary, helps provide an extra dose of control authority to permit the jet to execute all these maneuvers and more (for those useless little tricks at airshows) with flawless precision.

[Visiting /k/ommando No.3885761]

>>3885755
>>3885592
>I was reading that these days planes are being developed that are very unstable, but with advanced computers, they an harness that inherent instability and create maneuverability?
Yes, that's known as relaxed-stability, and it was pioneered by the F-16. You see, on a conventional-layout jet (canards are somewhat exempt), the center of gravity must be shifted on or slightly forward of the main wing's center of lift to achieve positive static stability. This means that the tail is not helping to produce a significant amount of lift, and is only there to stabilize and control pitch attitude.

With the advent of artificial stability, it became unnecessary to give an aircraft positive static stability, instead allowing a computer to hold the aircraft's attitude steady via continuous control deflections. This allowed the center of gravity to be shifted aft, shifting load onto the tail and allowing the tail to help produce lift at low speeds or while maneuvering.

Relaxed stability also helps massively improve supersonic maneuvering, since the center of pressure usually shifts aft as the sound barrier is passed, causing the jet to suddenly become OVERLY stable and making control authority the new limiting factor for how hard you can turn. Relaxed stability helps reduce the level to which the jet becomes overly stable as it passes the sound barrier, allowing a massive increase in supersonic control authority.

[Visiting /k/ommando No.3885781]

>>3885697
One that doesn't produce solid propellants; i.e. one with no metals in its reactants. Black powder and conventional perchlorate composite (APCP) propellants both contain some form of metal (potassium for BP and aluminum in APCP), and these leave dense solid particulate smoke trails composed of their respective metal-oxides. Many military rocket motors use nitro-compound based propellants (not unlike modern smokeless gunpowders) which do not contain any metals.

[Visiting /k/ommando No.3885815]

>>3885608
>Modern jets more or less can't fly without computers taking care of millions of calculations every second.
That's a bit of an overstatement; the control algorithms can actually be extremely simple, such as a simple PID algorithm based on a rate gyro input. The frequency at which it recalculates is actually not all that special or important.

Where things CAN get complicated, however, is where you start working in automatic control mixing algorithms like those used on the F-22. The F-22 uses ALL control surfaces for EVERY maneuver; not just the primary ones such as stabilators for pitch and ailerons for roll. It is also programmed to adapt itself in the event of damage, to find unorthodox solutions allowing the pilot to retain control in situations where he would otherwise be forced to eject.

[Anonymous No.3885825]

>It is also programmed to adapt itself in the event of damage

That is amazing.

[Anonymous No.3885831]

What do you think about hypersonic flight? Is it practical?

[Visiting /k/ommando No.3885869]

>>3885825
It is. I can only begin to imagine how complex such programming could get.

Let's look at a (fairly) straightforward scenario: Getting most of a wing blown off, like this Israeli F-15 did when it crashed into an A-4 Skyhawk. Obviously, if you pull up, the lift you're asking for is no longer going to be balanced, and will cause the aircraft to roll into the missing wing. Thus, there is going to be a strong pitch-roll coupling, most likely stronger than your ailerons can compensate for. The best way to compensate for this would be to limit pitch to the max that you can counteract with aileron, and mix in substantial amounts of aileron (and differential vectoring) to counteract the undesired rolling moments. Additionally, by yawing the aircraft, you could produce a significant amount of (lateral) lift without excessive undesired rolling moment - think of it as flying knife-edge, so that the fuselage produces all the lift and the wing produces none. From there, its up to the pilot to maintain the necessary airspeed he needs to preserve this control authority, steady the aircraft, and decide what his next move is.

[Visiting /k/ommando No.3885877]

>>3885831
It's practical with rockets, that much I know. Project Falcon is currently the hypersonic project I'm monitoring with greatest interest.

Airbreathing hypersonic propulsion is still in its infancy and is a decade at least from reaching an operational level of maturity, unless you include air-augmented rockets as "airbreathing."

[Anonymous No.3885900]

>>3885877
But what would be the purpose of these aircraft? Weapons delivery? Surely they would be unmanned?

[Anonymous No.3885916]

>>3885900
Yes, the Falcon is essentially a hypersonic cruise missile that employs a high-altitude boost-glide profile to fly 9000 miles at around mach 7, carrying a lightweight, precision-guided payload.

[Anonymous No.3885942]

>>3885900
Yeah, the vehicle more or less bridges the gap between ballistic missiles and cruise missiles. It's intended to carry a lightweight, precision-guided payload to a high-value target thousands of miles away at high hypersonic velocities (we're talking potentially mach 10+ here). The secret is that it uses a low-drag, high-altitude lifting reentry profile, not unlike that of the X-20 DynaSoar or Silbervogel intercontinental skip-gliders, which permit it to fly much farther than a fully-ballistic trajectory would allow.

[Visiting /k/ommando No.3885949]

>>3885942
Captcha ate my name. Sorry.

[Anonymous No.3886004]

>>3885942
Would the payload then be dropped? Or is the craft itself the payload?

[Anonymous No.3886011]

>>3886004
The glider is expendable (like a missile), and would most likely be guided right into the target with the payload aboard.

[Anonymous No.3886035]

>>3886011
Seems expensive.

That site I referred you to yesterday also has some stuff on the aerodynamics of hypersonic flight that is also interesting.

http://www.aerospaceweb.org/design/waverider/main.shtml

[Visiting /k/ommando No.3886085]

>>3886011
>Missed name
>Again
Was my fault this time, though.
>>3885544
>>3885569
I never really followed up with this, so I think I'll start now. Let me start off by explaining the different aspects of fighter maneuverability.

There are several different measures when it comes to fighter maneuverability, and some of them count more than others. In a close-in dogfight, for the most part you're looking at turn rate, which is measured in degrees per second. At longer ranges, where missiles are a bigger threat than guns, measures such as acceleration and G-forces become more important for evading missiles than turn rate, and thus higher speeds become desirable. Beyond visual range, maneuvering in general takes a back seat to matters such as airspeed, altitude, and tactical decisions such as avoiding detection. All these measures usually have separate instantaneous and sustained values, since it is usually possible to exchange energy for a few more degrees per second, or a couple more Gs, or another hundred knots of airspeed, or another few hundred feet a minute of climb rate over what your engines can sustain at constant airspeed and altitude. Furthermore, most of these are highly dependent on air density (i.e. altitude), and if applicable, airspeed as well.

[Anonymous No.3886099]

>>3885538
the technology in this thing is crazy.

[Anonymous No.3886131]

>>3886085
>Beyond visual range, maneuvering in general takes a back seat to matters such as airspeed, altitude, and tactical decisions such as avoiding detection

Do you believe this is one of the strongest aspects of stealthy fighters such as the F22 and F35? Their ability to engage targets BVR without detection?

[Visiting /k/ommando No.3886157]

>>3886035
It's intended only for high-value targets. Keep in mind that another contender for the "Prompt Global Strike" project that this is being funded by was a modified ICBM loaded with inert kinetic warheads; by comparison, this is a bargain.

And given the size and range of the glider, I'm fairly confident that it would be FAR more expensive to try to recover it than to make it expendable. The booster stage is debatable, though.
>>3886085
Another measure which has become increasingly popular since it was proposed in Boyd's "Energy-Maneuverability" theory is that of specific excess power (Ps), the instantaneous rate of change in aircraft specific energy, which CAN be generally indicative of both instantaneous AND sustained performance. It is also very descriptive of a jet's ability to climb and accelerate during a given set of conditions.

[Visiting /k/ommando No.3886177]

>>3886131
Yes and no. I believe the LO characteristics, combined with their flawless ability to work with other aircraft without betraying their position (thanks to the stealthy MADL datalink), are their two greatest assets. IMO, they don't even really NEED their own radar - an AWACS aircraft scanning for enemy aircraft and vectoring stealth escorts to go destroy them is an incredibly powerful air-superiority force. However, whether these fighters engage from BVR or closer range is largely irrelevant - if the right tactical decisions have been made, they should be able to attack most targets from even close WVR without being detected.

[Anonymous No.3886187]

Absolutely, regardless of what they're engaging.

[Visiting /k/ommando No.3886199]

>>3886099
Yeah, as it currently stands, I believe that the F-35, with its IRST, EO-DAS, helmet-mounted display and AIM-9X all-aspect engagement capability makes it every bit as deadly at close range as the F-22, if not moreso. The capability to fire missiles at a target right at your six-o-clock seems valuable indeed.

[Visiting /k/ommando No.3886219]

>>3886187
I wouldn't say that unequivocally, but the majority of targets lack the sensors necessary to reliably detect the F-22 (even WVR) before its too late.

Really, I feel that - with the kinematics of modern air-to-air missiles - BVR combat is simply ineffective if your target knows that you're there. The element of surprise is not just important in BVR combat; it is utterly vital for it to work. If your target detects you before you fire, you absolutely MUST close to WVR if you still wish to destroy it.

There are a few missiles currently being developed that may change this, but for now, this is the way it is.

[Anonymous No.3886226]

>>3886199
Of course. I think we can expect, in the future, similar upgrades to the F22's avionics and radar to those of the F35.

[Anonymous No.3886280]

anyone have any resources on introductory fluid dynamics?

[Visiting /k/ommando No.3886293]

>>3886157
Anyways, carrying on...

Now, instantaneous turns are limited only by the aerodynamic lift the aircraft is capable of producing, and of course how heavy the aircraft is. However, the limiting factor is not always the same. For instance, at low speeds, the limiting factor is (accelerated) stall - the aircraft can only pull a certain AOA and lift coefficient before flow separation causes a sudden drop in lift. Lift at stall is modeled simply by the standard lift equation, with Cl being equal to Cl-max - the maximum lift coefficient the aircraft can produce. Thus, it's clear that we want to minimize wing loading, and improve Cl-max, if we want to improve low-speed instantaneous maneuverability. Cl-max can be increased by using high-lift devices such as leading-edge slats or (less commonly) maneuvering flaps. Without either of these, Cl-max for a fighter is usually around 0.6; with slats, this can increase to ~1.5, and maneuvering flaps can add even more (the F-104 was capable of Cl-max of nearly 2 with its blown maneuvering flaps).

[Visiting /k/ommando No.3886305]

>>3886226
The F-22's radar is actually more powerful than the F-35's, but again, given how a stealth fighter will realistically be operated, it's largely irrelevant.

As for the other avionics, the F-22 is getting most of them, but few will be as powerful as the F-35s (i.e. the F-22's IRST will be considerably less sensitive), and the F-22 will not be getting HMDs or all-aspect AIM-9X launch capability at all.

[Visiting /k/ommando No.3886317]

>>3886280
I already posted it, but in case you didn't see it, I found this book (well, what's viewable through this google preview anyways) to be very helpful:
http://books.google.com/books?id=kaqvC4e_EKcC&pg=PA130&lpg=PA130&dq=introduction+to+airc
raft+maneuvering&source=bl&ots=BJA2zbX2Xv&sig=-o5y_h5H8lBc_IA36gRF6c-5QOM&hl=en&
ei=etKITfnkHJTqgQetp8S3DQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CB8Q6AEwAg
#v=onepage&q=introduction%20to%20aircraft%20maneuvering&f=false

I probably ought to buy a copy... I've read half of it already.

[Anonymous No.3886356]

>>3886317
>I've read half of it already.

Reading the preview? Lol.

Also, which maths are important for this field?

[Visiting /k/ommando No.3886376]

>>3886293
[cont]
As you accelerate to higher dynamic pressures (/indicated airspeeds), the amount of lift you can produce at this stall AOA increases until it finally becomes (at what is known as the "corner speed" or maneuvering speed) enough to actually exceed structural limits. This brings me to the intermediate limiting factor for instantaneous maneuvering; structural/physiological limitations.

This shouldn't be too difficult to understand; there is a finite limit to what the aircraft's structure can safely handle, and so the amount of lift you can produce suddenly plateaus as the pilot is forced to ease off the elevator to avoid overstress. Necessarily, the turn radius begins to increase here in a quadratic fashion, instantaneous turn rate suddenly switches from increasing with velocity to decreasing, etc. etc.

Most aircraft are instrumented/marked such that these structural limits are actually a G-loading limitation, but the truth is that a lighter airplane can actually safely turn harder and pull more Gs without damage than a heavily-loaded aircraft can. This is more complicated to instrument and model than a simple accelerometer though, so most pilots consider the gross-weight limitation an absolute limitation anyways, unless they include an alternate limit for "aerobatic weight" on the gauge as well.

[Visiting /k/ommando No.3886378]

>>3886356
For what I'm doing? Basic algebra is adequate.

[Visiting /k/ommando No.3886391]

>>3886356
For what I'm doing? Basic algebra is adequate. It's understanding the algebraic relationships, and what all the variables represent, that's the hard part.

And the preview actually has all the important stuff. I imagine the hidden parts are just more of the same.

[Anonymous No.3886393]

>>3883385
are you retarded. aeronautical engineering is one of the few fields that is growing like crazy in engineering. Weight is a big deal now, this means a massively increased number of design cycles for new planes. This means more designers are needed, more stress engineers and more V&V

[Visiting /k/ommando No.3886414]

>>3886376
Finally, there is ONE MORE limitation when it comes to instantaneous maneuvering - control authority.

While control authority isn't USUALLY a limitation for a properly-designed and loaded aircraft, many transonic and supersonic aircraft do reach a point where mach tuck begins to demand considerably more from the control surfaces for a given maneuver. Most fighters will suffer from this at high mach numbers (starting at 0.9ish) and low to moderate dynamic pressures - meaning it will be worst at high altitudes where the air is thin. However, before the advent of relaxed stability, some older fighters were control-limited even at sea level in the range of m0.9-1.2, before structural constraints became the limiting factor (again) at higher airspeeds.

[Visiting /k/ommando No.3886418]

>>3886414
Does anyone wanna hear about sustained maneuvering? Or am I just rambling at this point?

[Anonymous No.3886425]

>>3886418
I await your posts eagerly. Lol.

You have an audience.

[Anonymous No.3886452]

>>3886393
That is very good to hear.

[Anonymous No.3886505]

What is the likelyhood of being employed at a company like Lockheed or Boeing?

[Anonymous No.3886530]

>>3886505
I would imagine the odds of that happening would be quite low unless you displayed some sort of ability beyond those of your peers.

[Anonymous No.3886582]

>>3886530
Dang.

I've been subscribed to the LockheedMartinVideos channel on YouTube for a long time now, and the stuff they make is amazing.

[Anonymous No.3886618]

>>3886582
It really is.

[Anonymous No.3886628]

>>3886425
Alrighty, then.

The big difference between sustained and instantaneous maneuvering is that for sustained maneuvering, drag and thrust matter. The number-one qualifying condition for a sustained maneuver is that thrust = drag. If an instantaneous maneuver produces more drag than the engines can counteract, then this maneuver cannot be sustained.

For jet aircraft, this is most significant around the corner speed, where induced drag is greatest. At corner speed, and some ways to either side of it, you can usually produce more induced drag in an instantaneous turn than your engines can counteract. Since peak ITR occurs at the cornering speed, this can cause quite a large disparity between peak ITR and peak STR. At much lower speeds, however, there is a threshold where Cl-max becomes sustainable, due to the fact that both lift and drag get smaller as you slow down. At high speeds, drag usually remains the limiting factor, however since induced drag actually DECREASES with speed when lift is held constant, structural limit can sometimes be sustained at high speeds and low altitudes.

[Anonymous No.3886632]

>wouldn't a series of louvers be more efficient than a single flap at the trailing edge of a wing?

I'm not sure why that would be more efficient.

[Visiting /k/ommando No.3886641]

>>3886505
There was a Raytheon manager who stopped by /k/ a while back; he was apparently impressed by me, because he gave me an email address and told me to contact him once I get my degree.

Working for Raytheon would be cooler than either Boeing or Lockheed, IMO...

[Anonymous No.3886658]

>>3886641
Wow, that's amazing. Do you know what kind of stuff you would do if he gave you a job? I need to start studying so I'll be prepared for a chance encounter like that.

>>3886628
So, theoretically, if an engine with more thrust (excluding differences in weight, size, etc) is added to a jet, it would be able to perform tighter sustained moves? Or would lift be the limiting factor?

[Anonymous No.3886725]

Bumping with planes.

[Visiting /k/ommando No.3886770]

>>3886658
>Wow, that's amazing. Do you know what kind of stuff you would do if he gave you a job?
Not exactly. They build missiles though, and I have knowledge of rocket propulsion and some of aerodynamics, and I'm an ME major for whatever that's worth, so...

The thing I said that grabbed his attention in the first place, though, was how fascinating I found the rollerons on an AIM-9 Sidewinder. So effective, yet so elegantly simple...

>So, theoretically, if an engine with more thrust (excluding differences in weight, size, etc) is added to a jet, it would be able to perform tighter sustained moves?
Exactly. Basically, for a sustained level turn, you'e taking thrust and using it to counteract drag. Drag can be separated into parasitic drag (which is merely dependent on how big and streamlined the jet is while not producing lift), and induced drag (drag produced as a result of lift). The more thrust you have, the more induced drag you can counteract, and thus the more lift you can produce.

Of course, there are other things you can do to reduce induced drag from a given maneuver. I posted the simple relationship between lift and induced drag coefficients in [>>3883497]. It's been a while since I did the optimization, but I think I found that wing area and aspect ratio were both desirable, such that span was much more important than chord (It was chord*span^3 once aspect ratio was substituted out, IIRC). And of course, a lower weight ALWAYS lets you do more with the same amount of lift, so that's always a good thing.

[Anonymous No.3886776]

[Visiting /k/ommando No.3886782]

>>3886770
I should add, for the second bit, that the F-16 has received bigger and more powerful engines continuously over the different versions, but these versions have gotten substantially heavier as well as their systems and avionics and fuel capacities increased, enough so to essentially cancel out the sustained maneuvering benefits of the better engines.

[Anonymous No.3886787]

>>3886770
>span was much more important than chord
And that is when subsonic, correct?

If I remember correctly, a larger chord and sweep angle is more efficient when supersonic?

[Anonymous No.3886818]

>>3886782
>the F-16 has received bigger and more powerful engines continuously over the different versions

Let's imagine engine technology is created that increases thrust without increased weight or drag. At what point does an increase of thrust become less effective, and other factors play a larger role on performance, such as weight, aerodynamics, and structural integrity?

[Anonymous No.3886855]

[Visiting /k/ommando No.3886908]

>>3886787
Well... I was trying to prove that chord is desirable even for subsonic aircraft as well - just not as desirable as span. And that I did.

See, the frequent usage of coefficients and ratios in all these formulae tends to make people forget just what it is they're trying to optimize. By substituting span and chord for aspect ratio, and multiplying the coefficients by area (chord*span) to make them ACTUALLY represent the true magnitude rather than just a dimensionless coefficient, it can quickly be shown that reducing chord in order to increase aspect ratio is a silly thing to do, unless you have some other reason to limit wing area. Yet it seems as if aircraft designers do it anyways...

Another issue is that large-span wings produce more parasitic drag than short ones, and that they're harder to strengthen to 9-G stresses.

Sweep is a matter of reducing wave drag, as having a sudden spike in cross-sectional area (such as that when suddenly crossing a long, straight wing) is unfavorable and causes shock waves to build sharply in this region at right around mach 1 ("the sound barrier"). However, once you're over the barrier, these waves slant back and do not build up any longer, and wave drag settles down to flat supersonic levels.

[Anonymous No.3886926]

>>3886908
Ah. I see. Is there an optimal aspect ratio that should be achieved for most efficient flight, or are there many factors that go into determining that?

Do you have any references for all of the terminology used? Like in your photo, Mcrit, Mdd, etc.

[Visiting /k/ommando No.3886929]

>>3886818
In theory, if you kept increasing thrust without changing anything else, you could eventually reach a point where you could sustain any instantaneous maneuver, even your peak ITR at your corner speed. After this point, adding more thrust alone won't improve your sustained level turn rate any further; at this point, the only thing you can do is improve your ITR by strengthening or lightening your airplane for high speeds (to raise the structural limit), or lightening, adding wing area, or improving Cl-max to increase low-speed (Cl-max) maneuvering.

[Anonymous No.3886935]

>aeronautical engineering

http://www.youtube.com/watch?v=UJurYPXA_uw&feature=related

[Anonymous No.3886970]

>>3886935
I wish the vehicles were available in the demo.

>>3886929
That's what I was thinking.

[Visiting /k/ommando No.3886990]

>>3886926
>Ah. I see. Is there an optimal aspect ratio that should be achieved for most efficient flight, or are there many factors that go into determining that?
There are various factors...
What I've found is, for reducing induced drag, more wing is always better. Span is best, chord is good, it all helps. Parasitic drag matters as well of course, though, and thus for aircraft designed for low-altitude, high-speed, straight-line cruising (where parasitic drag is most significant), using less wing CAN help make it faster or more efficient. I guess it just sort of depends on what you're trying to do.

But yeah, if what you're trying to do is just improve the peak sustained turn rate of an airplane, more thrust, more wing, less weight is what you're looking for. Just don't be surprised if you ultimately wind up with something like a Super Cub doing 60 degrees per second at 40 knots, though. =P

[Anonymous No.3887022]

>>3886990
>Super Cub doing 60 degrees per second at 40 knots
Is that always good, though? If you have such a tight turn radius at such a low airspeed, will sustained high-speed turns be an issue? Is that a tradeoff designers must think of before building a new jet?

[Anonymous No.3887046]

Something about the massive air intake on the X-32 makes me think it would have a pretty big radar cross section.

[Visiting /k/ommando No.3887068]

>>3887022
>Is that always good, though?
Of course not. Just because my Super Cub can outturn an F-22 doesn't mean I can shoot one down.
>If you have such a tight turn radius at such a low airspeed, will sustained high-speed turns be an issue? Is that a tradeoff designers must think of before building a new jet?
Yep. Larger wings have more parasitic drag, so in terms of top speed (at low altitude, anyways), and low-altitude range, you're going to wind up making some major sacrifices. I almost wonder if they realized with the F-22 that they sacrificed low-altitude speed and range (which is rather important on a stealth aircraft) too much in the name of high-altitude maneuverability, and decided not to make that mistake again with the F-35.

[Anonymous No.3887083]

How about some. . . ASTROnautical Engineering?

[Visiting /k/ommando No.3887084]

>>3887046
Not necessarily. The intakes of most stealth aircraft are S-shaped, and often include splitters and such, designed to prevent radar waves from bouncing off the fan and back out again. Even if the waves aren't reflected off in some harmless direction like external waves are, the RAM coatings inside the intake can absorb them quite efficiently, especially if they have to reflect multiple times to make their way back out again.

[Anonymous No.3887100]

>>3887068
>I almost wonder if they realized with the F-22 that they sacrificed low-altitude speed and range (which is rather important on a stealth aircraft) too much in the name of high-altitude maneuverability
>(which is rather important on a stealth aircraft)

Sure, but is it really important for the F22? Is low-altitude maneuverability essential for the air-superiority role?

>decided not to make that mistake again with the F-35.
Striving for low altitude capability is understandable for the F35 because of it's ground support role, right?

[Visiting /k/ommando No.3887105]

>>3887083
I'm bummed that the Ares I was cancelled. From an engineering standpoint, that rocket just made too much sense.
>Heavy solid-fuelled first stage, high volume-specific impulse with plenty of grunt, low cost, AND it's reusable
>High-energy hydrogen fuelled upper stage
It could've been America's R-7... a good, solid, inexpensive workhorse of a rocket...

[Anonymous No.3887118]

>>3887068
>I almost wonder if they realized with the F-22 that they sacrificed low-altitude speed and range (which is rather important on a stealth aircraft) too much in the name of high-altitude maneuverability
>(which is rather important on a stealth aircraft)

Sure, but is it really important for the F22? Is low-altitude maneuverability essential for the air-superiority role?

>decided not to make that mistake again with the F-35.
Striving for low altitude capability is understandable for the F35 because of it's ground support role, and to compliment it's stealth, but again, does the air-superiority fighter of the 21st century still rely on near-ground acrobatics?

[Anonymous No.3887127]

>>3887068
>I almost wonder if they realized with the F-22 that they sacrificed low-altitude speed and range (which is rather important on a stealth aircraft) too much in the name of high-altitude maneuverability
>(which is rather important on a stealth aircraft)

Sure, but is it really important for the F22? Is low-altitude maneuverability essential for the air-superiority role?

>decided not to make that mistake again with the F-35.
Striving for low altitude capability is understandable for the F35 because of it's ground support role, and to compliment it's stealth, but again, does the air-superiority fighter of the 21st century still rely on near-ground acrobatics?

[Anonymous No.3887164]

>>3887084
Why was the intake so large anyways? I watched the documentary but still didn't understand it.

I wonder why they didn't employ a more common dual-intake configuration like the F35.

[Visiting /k/ommando No.3887188]

>>3887127
At high altitude, even a stealth aircraft is much easier to spot on radar. The F-22's incredible high-altitude performance - including its supercruise capability, which is not possible at low altitudes - is only safe to exploit once its stealth benefits have been rendered largely unnecessary - that is, after low-flying strike aircraft like the F-35 have destroyed radar threats. The only reason the F-35 even exists is because the F-22 was not suitable for the low-altitude strike role, owing to its tiny weapons bays (inadequate for filling with bombs or anti-radiation missiles, or even regular-sized air-to-air missiles), and its compromised low-altitude performance.

Add on to this the fact that 80% of our enemies' Air Forces get destroyed by strike aircraft before they even leave the ground, and its easy to see why the F-22 was cancelled in favor of more F-35s.

[Visiting /k/ommando No.3887255]

>>3887164
>Why was the intake so large anyways?
Because there was only one of them.
>I wonder why they didn't employ a more common dual-intake configuration like the F35.
Because there was only one engine, and they didn't have to make their intake go around the sides of a big lift fan.

[Anonymous No.3887272]

>>3887105
ATK is still trying for something like the Ares I: the Liberty rocket would have an SRB first stage and an Ariane 5 upper stage. They are desperate to have *some* sort of continuation of their SRB heritage.

[Visiting /k/ommando No.3887275]

I've gotta go to class, but I'll be back later to continue discussion if there's any remaining interest.

When you're not going on about economics or religion, you guys ain't so bad, /sci/.

[Visiting /k/ommando No.3887284]

>>3887272
Yeah, but after round two of COTS, they have lolnofunding.

I really, REALLY hope it gets picked up again. Too bad ATK doesn't know how to handle liquid rockets for themselves... I think the fact that they were trying to involve foreign companies was a put-off for Liberty.

[Anonymous No.3887340]

>>3887188
True.

>At high altitude, even a stealth aircraft is much easier to spot on radar
On ground radar, or aircraft radar, or both?

[Anonymous No.3887357]

>>3887255
Is there any advantage to having dual or single air inlets?

[Anonymous No.3887422]

>>3887255
The f35 looks badass wen transforming.

[Anonymous No.3887442]

[Anonymous No.3887476]

[Anonymous No.3887531]

>mach pulse supercharger
??

[Anonymous No.3887646]

>>3887531
speaking of the F119-P100...

[Anonymous No.3887671]

[Anonymous No.3887681]

[Anonymous No.3887719]

Does anybody want to talk about anything? ;_;

[Anonymous No.3887773]

Last bump for a while...

Anyone there..?

[Anonymous No.3887774]

>>3887773
maybe

[Anonymous No.3887796]

>>3887774
Do you have an interest in aerospace engineering? :P

[Anonymous No.3887801]

>>3887796
nope but i like pictures of the F22

[Anonymous No.3887817]

>>3887796
i quit from that course, my own decision. regret a little.

i'll answer any questions you have.

[Anonymous No.3887853]

>>3887817
How far along in the course did you get? What did you learn?

>>3887801
It's a beautiful plane.

[Anonymous No.3887899]

>>3887853
3 years
a bit of everything - propulsion, aerodynamics, aircraft structure, design analysis, flight controls, materials, dynamics, maths, physics....

[Anonymous No.3887925]

>>3887899
What was your favorite part?

[Anonymous No.3887952]

>>3887925
don't have one lol

i'm pretty good with materials though

[Anonymous No.3887964]

Did anyone here do design/build/fly in college like me?

[Anonymous No.3887993]

>>3887964
I make foamies and I'm currently in High School.

>>3887952
Cool cool. Was the class very hands on, or did you work out of a book, or what?

[Anonymous No.3888051]

>>3887993
books, journals and a few labs. mostly the former two.

[Anonymous No.3888073]

>>3888051
That is very cool. Were you pursuing an aerospace engineering degree, or something similar?

[Anonymous No.3888159]

>>3888073
yeah i were

are you thinking of doing it?

[Anonymous No.3888190]

>>3888159
I am, yeah.

[Visiting /k/ommando No.3888407]

>>3887340
Both. Targets below the horizon are obscured by ground clutter at best, and completely masked by terrain at worst. Terrain masking is 90% of why those "stealth" helicopters they used to go kill Bin Laden got so far into Pakistan undetected. Low RCS certainly helps make an aircraft harder to detect, but even today, terrain masking is still king.
>>3887357
Not particularly, no.
>>3887422
The X-35's transformations looked cooler than the F-35B, but I gotta admit, the F-35 (A,B,C)'s weapons bays are fookin' sexy.
>>3887646
They should've gone with flat (rather than round) nozzles on the F-35. Even if they didn't vector, they're mechanically simpler and they help reduce the jet's thermal signature substantially.
>>3887964
I fly a lot, but I don't do much building anymore. I have a bunch of the new BNF micros from Horizon - the Parkzone Vapor (a definite favorite), SU-26m, Eflite MCP-X (incredible, indestructible 3d helicopter), Beast (my favorite for outdoor flying), Parkzone P-51, the DeHavilland Mosquito... Oh yeah, and the Corsair. They're just too great - they fly well, they're cheap, and best of all, they bounce when they crash.

[Anonymous No.3888433]

Fly's have outdone us 450 million years ago. What do you say to this?

[Anonymous No.3888479]

>>3888433
450 million years of perfected flying technology but their PR is still so shitty that people can't even spell their name right?

Flies truly are the insect-version of engineers.

[Visiting /k/ommando No.3888491]

>>3888433
I dunno how many flies I've had to scrub off my windshield, but I know I've never had to be scrubbed off a fly.

[Anonymous No.3888512]

>>3888433
Flies vs F22 in a dogfight would be a sight to see.

>>3888407
>they're mechanically simpler and they help reduce the jet's thermal signature substantially.

They look pretty cool, too. :P Do they cool the exhaust quicker than the round nozzles somehow?

[Visiting /k/ommando No.3888526]

>>3888512
They create a wider, flatter, thinner exhaust jet, which is harder to detect from above or below.

Basically, the layer of hot air an infrared seeker has to "see" through is thinner.

[Anonymous No.3888571]

>>3888526
Is there a specific reason why round nozzles were used? Cost maybe?

[Anonymous No.3888646]

>>3888571
Perhaps. I think it might have to do with the VTOL; they probably weren't sure how to make a rectangular nozzle vector to 90 degrees.

[Anonymous No.3888689]

>>3888646
You're probably right. Getting a nozzle like the F22's to do that would take a lot of time and money.

Can they perhaps make a rectangle shape with the same material as the current nozzle? I don't see how that would prove to be a challenge but as you can tell I'm not not exactly an expert. :P

[Anonymous No.3888750]

>>3888689
I don't see why materials would be a challenge at all. I believe the exhaust stream is already mixed and homogeneous on both jets (again for the sake of reducing thermal signature, so shape should not have a significant impact on thermal limitations.

[Visiting /k/ommando No.3888763]

>>3888750
Ahem. Forgot my moniker again. /k/ is tolerable again so I've been bouncing back and forth.

[Anonymous No.3888845]

>>3888750
What kind of material do you believe is used in >>3888646 for the nozzle?

It seem fairly exotic.

[Visiting /k/ommando No.3888938]

>>3888845
Probably just a ceramic-coated steel...

Then again, with as much money as goes into these, they might be all-ceramic to save weight... I know steel can handle the heat there, though.

[Anonymous No.3889041]

>>3888938
That's cool.

>but even today, terrain masking is still king
Is terrain masking even possible with a fighter jet?

[Visiting /k/ommando No.3889044]

>>3889027
Yep. It's called a horizon, and it's a lot closer to you when you're at 500 feet AGL than 20,000 feet.

[Anonymous No.3889083]

>>3889044
Oh, right. Of course. Lol.

How do you feel about the performance of flying wings? If they're heavily computer controlled, like the F117, do you think they can be a viable platform for UAV's or future fighters?

[Visiting /k/ommando No.3889337]

>>3889083
I honestly don't think relaxed stability will help tailless aircraft nearly as much as its helped conventional aircraft. Nevertheless, I've always been a big fan of tailless deltas like the F-106, due to their incredibly low wing loading and potentially excellent energy-maneuverability characteristics. However, due to the short control moments of their elevons, tailless aircraft suffer from strong susceptibility to performance losses due to longitudinal load variations. For one, they are constrained to a very narrow CG envelope. For another thing, the pitching moment produced by their wing MUST equal zero, meaning some sort of airfoil reflex or washout must be used, and high-lift devices such as flaps are out of the question. The result of this is that their Cl-max is usually very low, offsetting their incredible wing loadings.

The current popular solution in Europe - the delta-canard - is a simple and elegant solution to almost all these problems. Another effective solution that may see increasing use on tailless stealth aircraft is the usage of thrust vectoring as a substitute for large aerodynamic control surfaces, as with the X-31.

Now, as for the pure flying wing, I don't think they'll be very useful for manned aircraft, due to the often terrible cockpit visibility they suffer from. UAVs can and are using the layout already, but not in an air-to-air role of course. But for the most part, even if tail elements are soon eliminated for RCS reasons, some semblance of a fuselage will most likely remain.

[Anonymous No.3889370]

>>3889337
>the delta-canard

As you mentioned, I see this on many European planes. Is there some sort of inherent advantage to this set-up?

[Anonymous No.3889379]

hey question for AEfags, is your job enjoyable? and why did you pick AE over mechanical? And do you regret it?

[Visiting /k/ommando No.3889463]

>>3889370
It's a simple way to get some of the same benefits that relaxed stability offers. Of course, modern canards are fly-by-wire anyways, and this does help fine-tune the effect.

Canards do not interfere with large delta-wing layouts, permitting nearly as low wing loadings as tailless deltas offer. And while they usually aren't effective enough to counteract the downward-pitching moment produced by trailing edge flaps, they DO reduce or eliminate the amount of elevon deflection required to reach high AOAs, thus increasing Cl-max significantly over tailless deltas. Additionally, close-coupled canards can act similarly to LERX, delaying stall at very-high AOAs and thus increasing Cl-max even further.

If it's any testament to the aerodynamic advantages of delta-canards, my little analysis above applied to the Eurofighter Typhoon showed that the Typhoon offered nearly identical sustained maneuvering as the F-22, despite the Typhoon's MUCH LOWER thrust:weight ratio.

[Anonymous No.3889478]

>>3889463
>Typhoon offered nearly identical sustained maneuvering as the F-22
Really? That's amazing. So with increased thrust to weight ration, the Typhoon could potentially out maneuver the F22?

[Anonymous No.3889556]

>>3889478
Yep, supposedly so.

Though I don't recall which weight figures I used, so the comparison mightn't have been completely fair...

(And don't forget, the F-22's handling isn't the only thing it has going for it.)

[Anonymous No.3889670]

>>3889556
Nice.

What field of work do you see yourself doing in the future? Like, what role do you see yourself performing if you were hired at Raytheon? Designing missiles or something like that?

[Visiting /k/ommando No.3889752]

>>3889556
Alright, here.

Weight spec: empty wt + 50% internal fuel + 1000 kg (slightly favors the Typhoon due to the Raptor's abnormally large internal tanks)
F-22 max sustained-G at 220 m/s and sea level: 8.141 Gs
Eurofighter max sustained-G at 220 m/s: 8.213 Gs

Both of these used a Cd-0 of 0.025 (pretty much just a total guess), and assumed an Oswald efficiency factor of 0.9. Overall, it's DARNED close.

[Visiting /k/ommando No.3889798]

>>3889670
I don't know, exactly. I'd probably be happy with whatever they'd have me do.

Until recently, though, I'd figured my greatest area of interest was thermodynamics, particularly with engines and heat pumps. I have of course always loved aeronautics as well, but I always viewed that as a more competitive and less applicable field than general M.E.. I wouldn't object to a technical job in refrigeration or HVAC, if it came to that, though whatever I end up doing, I'd prefer to actually be more of an engineer than a technician.

[Anonymous No.3889881]

>>3889752
AH, now I remember what it was. I originally listed all the equations out on my Ti-84+, and rather than performing the substitutions manually, I just inserted the functions into one another and let the calculator do all the hard work. Then I found the PEAK theoretical STR for each aircraft, regardless of the airspeed it occurred at. The F-22's peak was absurdly low - around 150 m/s - and then tapered off relatively steeply. The Eurofighter's plot rose more gradually, peaked at around 200ish, and then began falling again. That's why I'm getting these results now, whereas the earlier plot showed (reasonably) clearly that the F-22 was about one to two degrees per second better.

And I wish I had some real data to base my Oswald and Cd,0 numbers on. Maybe I should build myself some wind tunnel models...

[Anonymous No.3891994]

>>3889881
Do it. This is very interesting stuff.

[Anonymous No.3892473]

this is the oldest thread on /sci/ lol

[Anonymous No.3892710]

for i'm kind.

[Visiting /k/ommando No.3892890]

>>3891994
What do you want me to do now? Plot turn rate vs. time and post it?
>>3892473
You're welcome. =P

[Visiting /k/ommando No.3893237]

>>3891994
OH, you want me to build a wind-tunnel model...

I don't actually have a wind tunnel, but I'm tempted to just strap a model to a pylon under the wing of my Super Cub or the roof of my truck and test it that way. 'Course, I don't have the proper sensors and gauges to measure the forces it produces, so at this point it'd kinda be pointless until I develop some way to do that. Also, I'd need to study up on Reynolds numbers and scalability to see if the model behaves inviscidly enough to be applicable.

[Anonymous No.3893288]

>>3893237
You better get on that. :P

[Anonymous No.3894102]

>>3893237
Don't forget to post your maths.

[Anonymous No.3894242]

>>3893237
Buckingham Pi Theorem. I would see problems with using an open circuit wind tunnel such as the outside world.

[Visiting /k/ommando No.3894335]

>>3894102
I wish I still had the paper I wrote everything on from when I was flight-testing an RV-6... it got a new set of streamlined wheelpants and a tighter cowling, and I wanted to quantify exactly how much parasitic drag it had saved. It came out to around 5.5% reduction of the initial Cd,o of 0.21. The measurements were taken under power across a triangular course, so I had to use Lycoming dynamometer data to find the power output at those settings, and calculate the propeller's efficiency as well. I'd redo it all for you guys to see, but I don't have the data on me anymore.

Ah well... next time I go flying I'll play test pilot and take SOME sort of measurements for you guys to play around with.

[Anonymous No.3894454]

>>3894335
I would definitely appreciate that.

[Visiting /k/ommando No.3894539]

>>3894242
>Buckingham Pi Theorem.
Yeah, we're just getting to that now in my fluids class. Still don't understand it though - I kinda fell asleep in class that day...

>I would see problems with using an open circuit wind tunnel such as the outside world.
If it's good enough for George Cayley, it's good enough for me.

Besides, from what I hear, the 'outside world' is the best wind tunnel there is. In terms of fidelity of data, it goes open-air flight data > wind tunnel data > CFD garbage, according to my uncle. Apparently the only thing they're really using their CFD resources for are to make pretty pictures to appease the board of directors. (Of course, the rough "use a ruler where you can and just wing it from there" that I've been doing in this thread so far is a whole other level below - but that doesn't mean it's COMPLETEY meaningless, though).

[Anonymous No.3896793]

AE second year here, bumping the thread since I finally reached the end of it.

Hoping /k/ guy comes back.


I'm not doing that great in my calc 3 (for the second time) class, is this a good indicator of how I'll be doing in the future? Should I not continue with AE, even though its what I really want to do?

[Visiting /k/ommando No.3896940]

>>3896793
I'm not studying AE, I'm studying ME. All the stuff I'm using in this thread is self-taught, and none of it requires anything more difficult than basic algebra and a half-decent understanding of classical mechanics.

In my fluids class, however, we ARE touching upon calculus here and there, including multivariable calculus, though. Is Calc III multivariable calc or transcendental functions where you're taking it?

[Anonymous No.3896957]

>>3896940
Multivariate calc.
Stuff like gradients, triple integrals, line integrals, etc...

I failed it last semester, so I'm taking it again, and I definitly understand the stuff we're going over, I'm just not getting good grades...

[Anonymous No.3896978]

>>3896793

I guess they're probably not in your degree but the courses in mine that has built on multivariable calculus so far has been electrodynamics and analytical mechanics and a course on differential equations.

[Anonymous No.3897002]

>>3896978
I do have to take diff. eq. It might actually be a pre req for some of my AE courses.

I'm not sure about electrodynamics, the only E and M course I have is basic circuits.

If by analytical mechanics you mean Statics and Dynamics and Def Bods, then I have those too.

Its not looking good...

[Anonymous No.3897035]

>>3897002

By analytical mechanics I mean classical mechanics done with Lagrangians and Hamiltonians.

But you can get by without most of it. It's at most a couple of partial derivatives.

[Visiting /k/ommando No.3897053]

>>3896957
Hmm...

I had to retake multivariate calc too, and even then I only got a C, but the basic multivariable stuff (partial derivatives, multiple integrals, related rates, etc.) wasn't too hard for me - it was those theorems and whatnot (stokes theorem, etc.) that really got me. Anyways, so far we aren't really using those in fluids, but we are using partials and a bit of double integrals (though they're really easy ones). I don't know what else we might come across, but so far if you can handle that stuff, you can do as much as I have...

Also, multivariate is a pre-req to differential equations, which I think should prove to have some major engineering applications eventually.

[Anonymous No.3897125]

>>3897053
Yeah that simple stuff is no problem.
IT was the second half that killed me, just like you. I'm probably looking at a C for this semester, but I like the teacher a lot more, and my understanding is better so far, so possible a b...

Diff. eq is not a pre req for most of my first level actual engineering classes, I don't think. But calc 3 (multivariate) is not a pre req for diff eq here

>>3897035
Ah, I don't think I have any of that. The only "classical mechanics" I had was classical physics one, which was a joke.

[Visiting /k/ommando No.3897686]

>>3897125
I took all my math at a CC, and I wasn't quite sure which college I would end up transferring to, and the Uni I wound up at actually wound up NOT requiring differential equations for M.E. majors (at least, not at the undergrad level), much like yours, apparently. Still, I'm glad I took it, because it really does seem like something that could potentially be extremely useful within the field of engineering.

[Anonymous No.3898316]

>>3897686
Oh, i'm absolutely taking it haha.
Just whether or not its required for my major specific courses