Demistifying Eagle damage model

Im glad we have guy that has to read actual manual and take it serious.

 

 

Are you serious?

You are the one saying jet fuel can't be atomized.

This must be a joke. Unbelievable. You said I believe in false theories, which is far from being true. I think the only person here who believes in such a thing is you. First thing I do when I quote someone on the subject is, I open the books I use to study and I make sure I am not sharing wrong information.

I am sorry but this is getting ridiculous.

@David OC ttaylor obviously can speak for himself but lawyers assistance is always beneficial.

So let me post you again:

-atomized fuel.. fine, but word meaning is misleading cos you cant atomize molecules, nevertheless, its about air (n78%,o21%,x1%) jet fuel(CnH2) mixture in various rate that is flammable if temperature is above 40°c (flashpoint), if t>220°c autoignition occurs. Exhaust gas temperature is >800%c so you can easily ignite leaking fuel that creates fuel-air mixture cloud behind leaking plane by use of afterburner, that's why egg. f18abc flight manual says that it is FORBIDDEN to do so, ttaylor should know that. Heat is transferred in 3 ways: mixing, transmission and radiation. Fuel/air combo burns at >1000°c (and is/was used in napalm) but that heat is sometimes enough to melt skin of fighter plane which is mostly made of aluminum (composites, steel and titanium have higher melting point) that melts above 600°c. Concerning origin of fuel dump/leak spot and time for fuel to completely scatter and slow down enough to ignite, fireball will be closer to skin, closer to skin, faster it melts, if it melts it loses aerodynamic function etc.. tivial.

-mig29 collision image has sequel where complete plane is engulfed in flames cos fuel mist entered engine. its just few seconds later on video.

David OC, get real man, we don't talk conspiracy sh* here, were talking mechanics and physics not being implemented right way on F15 model in DCS. RL parallel is that IAF mystique one winged jedi flight that is by my complete understanding, knowledge and experience complete forgery. If your'e scientist or engineer, please be free to counter any claim from start by numbers or graph. If you're somebody's lawyer, please change profession.

@Vitormoura, are you payed to post such claims? You can call it "quarkized" but it wont dissolve to quarks. There is only one form of fuel/air mixture cloud behind leaking plane, and it damn burns hot if ignited in any way.

FA18 Manual, page I-2-14/Change 6: "Simultaneous selection of fuel dump and afterburner during high AOA maneuvering may cause fuel to ignite with resulting fuselage damage."

The only upper limit of landing speed is tire limit, lower is stall. Pilots must stay in between to stay safe, every pilot knows that.

If ED based F15C damage model on IAF case, I say its wrong and that's my conclusion. ED doesn't have to listen to me or anybody else but I hope they will fix this dm saga.

I also hope that no AF pilot will ignite fuel cloud by afterburner if leaking from wing tank, that's bad thing to do. Stay safe. Godspeed.

ED based it on official documents - and what you mean is the flight model, not the damage model.

No one cares what your understanding is - sad fact is that you keep saying it's a forgery, but it's an actual real fact, examined by the very engineers who built the aircraft and analyzed in wind tunnel tests.

Also, your fuel analysis is irrelevant. No matter how much you want it to happen your way, that isn't how it happened.

I'll say it again, logic and engineering - and any science for that matter - is a GIGO (garbage in, garbage out) affair.

Put in garbage assumptions, garbage comes out. You've put in garbage assumptions - the first of which is applying rules of thumb and failing to consider explanations other than your postulates - in other words, your assumption that things happened exactly as you say they happened.

Your assumptions aren't facts. They're assumptions. I'd tell you to stop while you're ahead, but it's a little late :)

I trust the NASA reports a bit more than I trust your assumptions :)

BTW, flight manuals say a lot of things are forbidden. How many 12g over-g cases do you think there are for F-15s? 11? 10? Take a guess. Or if you prefer, do a bit of actual research. ;)

If ED based F15C damage model on IAF case, I say its wrong and that's my conclusion. ED doesn't have to listen to me or anybody else but I hope they will fix this dm saga.

At least you learnt a new word today jackmckay :)

In English, 'Atomised' (atomized in US) means turned into a fine vapour or mist.

A perfume spray bottle is an atomiser.

You're quite right, jet fuel is not 'atomised' in the sense that it is decomposed into atoms prior to ignition, but no one was saying it is. It is 'atomised' in the sense that it is turned into a fine mist.

The whole flying home with one wing thing may seem unlikely to you - but so far you only seem to have established that you believe it unlikely (The fuel would likely have ignited, someone would probably have noticed the wing missing, the tyres would probably have burst).

That something is unlikely does not mean it won't happen.

I rolled a lidless jar of mayonnaise off my kitchen bench a month or so ago, and when it landed on the floor it shot a jet of mayonnaise up that ran all the way up my shirt and hit my ceiling 2.5m above the floor (like my very own shaped charge explosively formed penetrator. Now the ceiling need re-painting). You couldn't make it happen again if you dropped jars till you dropped dead, but though very unlikely, it did happen.

Same with Lydia Ko hitting a 3-wood to 3 feet for eagle last Sunday. She undoubtedly hit a good ball, but also benefitted from turbulence and wind gusts that are both unpredictable and impossible to replicate routinely.

Sometimes the stars line up.

Lets for a moment accept your argument that 9 times out of 10 you'd expect the fuel to ignite, and 9 times out of 10 the tyres would burst & 9 times out of 10 the airframe would be in a flight regime that would immediately cause the pilot to lose control, so the chance of the pilot surviving all these is 1/1000.

That doesn't meant it didn't happen.

The odds of winning LOTTO in GB are one in 45,057,474, yet there are literally thousands of people running around GB who have done just that.

To prove it didn't happen, you don't have to show it is very unlikely, you have to show it's impossible, and nothing you have done so far comes close to that.

I wonder if this is how they recruit?

Step 1. Begin illogical argument

Step 2. Note who takes your side

Step 3. Recruit

Step 4. ????

Step 5. Profit!

jackmckay, did you really think that atomizing is breaking a molecule apart ?

If yes, well then look into how a diesel engine works, and try to light diesel on fire with a simple gas lighter.

Also, that would close this thread, seriously.

zukhov&flow are you engineers?

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Something I've noticed about arguments online:

#1 Nazis are eventually mentioned. Like they just were.

#2 When arguing with someone, they inevitably claim to be a leading expert in the field of *insert topic*, declare you obviously don't know what you're talking about or you wouldn't be disagreeing with them, then demand your credentials (which are worthless, as this is the internet and everyone can lie and claim they are anything they want to be).

zukhov&flow are you engineers?

 

 

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Yes, and what is the point of that question ?

Zhukov looks good in psychological profilation so I suggest profiling Nadiev statements as f15 pilot. Flow if you're engineer than why dont you stick to the topic then and use all your engineering skills to counter my claims?

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:megalol::megalol::megalol::music_whistling:

Troll section is down the corridor guys :)

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Troll section is down the corridor guys :)

 

 

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Ow i thought you was the troll section? I was on the edge of enjoying myself with your post and kill myself. Jeebus... you argue like a conspiracy theorist. You take the scientific method on "question everything" to a new level. Mixing bullshit with actually good points to confuse people. You are like the governments you probably dislike yourself. If you are a engineer i might think twice getting into any vehicle. Cause that would mean even engineers don't follow scientific methods.

We need to call SecureTeam10! :D

Yes they do by default. Here comes the conclusion. The only thing that could save this pilot is miracle, and it obviously happened. Statistical possibility for IAF case to happen again are in milion scale. And it seems that I was possibly wrong about one key point: counter drag. After midair, remaining wing could have had enabled enough drag to counter extreeme yaw momentum due to missing large portion of wetted area. Stable state was not possible to achieve by any remaining control surfaces or engine power if complete wing was missing, burning afterburners on leak was highly dangerous too. It looks that remaining of flap held missing wing crossection drag. Nothing else in the world could have save him and it looks by the pictures that it was the only solution. But thing about wing hidden in cloud of fuel could be very subjective view of pilot in trouble. But at the end, its not whoole wing missing, god gave him another smaller but draggy enough in place. What did the wingman saw? He couldn't catch him on afterburner? I will laugh for weeks. Ps. Where are that engineers here?

Who cares about the engineers? You may as well have said the earth was flat.

The pilot story is retold many times, we don't know how many times it has changed. We don't exactly know what the pilot was thinking or what he said- there are a lot of suspicious things in the stories for sure, that make them sound like they were not told by the pilot.

The most reliable data so far is from the NASA report. I have no seen the McAir report and I'm not sure if it's available.

I don’t know if you’ve actually played dcs, but planes tend to get very small very quickly. Try this: fly formation with an AI. Then, rapidly break off, in a steep dive. How long I can you tell how many wings he has without zooming in from the external view of the AI?

As mentioned earlier, he was only 10 miles from the airport. This didn’t take place over 30 minutes or anything like that, the whole time from collision to landing was probably only 2 minutes at most. What makes you think the wingman had time to confirm the safe ejection of the A-4 pilot, talk to ATC, turn around, find his wingman, and join up with him in that amount of time, especially while following the sometimes wildly out of control aircraft?

Yes they do by default. Here comes the conclusion. The only thing that could save this pilot is miracle, and it obviously happened. Statistical possibility for IAF case to happen again are in milion scale. And it seems that I was possibly wrong about one key point: counter drag. After midair, remaining wing could have had enabled enough drag to counter extreeme yaw momentum due to missing large portion of wetted area. Stable state was not possible to achieve by any remaining control surfaces or engine power if complete wing was missing, burning afterburners on leak was highly dangerous too. It looks that remaining of flap held missing wing crossection drag. Nothing else in the world could have save him and it looks by the pictures that it was the only solution. But thing about wing hidden in cloud of fuel could be very subjective view of pilot in trouble. But at the end, its not whoole wing missing, god gave him another smaller but draggy enough in place. What did the wingman saw? He couldn't catch him on afterburner? I will laugh for weeks. Ps. Where are that engineers here?

What about the very turbulent air flow generated by the damaged airframe, creating a lot of drag ? Is that an option in your theory ?

Did you calculate it ? Simulate it ? Any formulas to share or are we going to compare youtube videos again ?

I will laugh for weeks.

You can have years of that, just re-read yourself every now and then. Fav this post.

Ps. Where are that engineers here?

This is just discrediting you honestly. Engineer is just a title. I'm a PhD for that matter, does that make my opinion superior to yours ? The answer is no.

I'll leave this here, you might recognize yourself :

If you just stick to the disproving of the F-15 on the first page, you post should have more substance in it. "As an engineer"

What would that look like? if you want other "engineers" to answer you seriously.

Example below: One of the best examples around here by a real engineer.

We could perhaps ask Curly to pull this right apart for you if you like? For "some reason" I don't think he would be interested tho....?:D

Pitch for AOA and throttle for glide slope is also know as the backside technique. It predates fly by wire control systems. The backside technique is first recommend by the Naval Safety Center in June of 1959. NASA had looked into earlier of that year.

 

 

The Flight path angle is = D/L - T/W + dV/dt/g

 

Thereby flight path angle is a function of lift to drag ratio at approach speed, thrust to weight ratio and the rate change of airspeed.

 

It was found in a lot of aircraft configurations that the lift to drag ratio decreases at high lift coefficients. Total drag increases with decreasing airspeed, this is as the region of reverse command or the backside of the drag curve.

 

The speed for minimum drag will also be the speed for neutral speed stability. At speeds higher than that for minimum drag, the airplane will return to the trim speed following a disturbance. At lower speeds following a disturbance the aircraft will diverge in speed.

 

 

So what happens when you pitch up to correct for a low glide slope. First you change the L/D and add more drag thus slowing the aircraft down. You’re now on the backside of the drag curve. As the craft slows, your sink rate increases. You’ve also slowed the craft to where it’s no longer stable. Now you’re sinking and slowing.

 

If we’re pitching to fix glide slope, at this point we would pitch up further to correct for our increased sink rate… you’re in a death spiral. Each increase in pitch compounds your problem, as L/D gets worse and you slow down more and drop at a faster rate. You pull back trying to fix your problem and stall. If you’re flying a turbofan with a engine lag, like an early jet or an F-14, or a aircraft with a low thrust to weight ratio, you may be out of options. The engines won’t spool in time to save you.

 

Even if you manage to stay on the throttles to fix your speed problem and avoid a stall, you’ve put the aircraft into a state where making a precision landing will be extremely difficult. Remember what said about speed stability, Well because we pitched up and slowed down our speed stability is gone and the now the aircraft is a a phugoid. The task of controlling the approach with any precision is now orders of magnitude more difficult as the craft pitches about while changing speed.

 

 

The key aspect to understanding why this technique is used is often overlooked and relates to stability. The start of this technique is predicated up on the fact that we are trimmed for level flight before turning on final.

 

If the aircraft is in a steady state, we say that all the forces acting upon it are in equilibrium. Thus

 

Our speed = 17.2* Sqrt Gross Weight / Wing Surface / Lift Coefficient.

 

Or 17.2 * Sqrt of Wing Loading / Lift Coefficent

 

So if we pull back on the stick, we increase the lift coefficient on the tail, and increase the total lift coefficient. Thus reducing our speed. Hence we pitch for speed.

 

In a steady state our rate of climb or descent in feet per minute, is = 33,000(Power available - Power Required for level flight / Gross Weight)

 

So our sink and climb rate is a function of excess power. Since we can modulate the amount of excess power with the throttle and maintain speed stability, we use the throttle to control glide slope.

 

 

Really the best guides to understanding why this technique is used are the primary sources.

 

Aviation for Naval Aviators offers a in-depth expiation in chapter 6.

https://www.faa.gov/regulations_poli.../00-80T-80.pdf

 

The early NASA document on landing approach speeds does a nice job of explaining as well.

https://ntrs.nasa.gov/archive/nasa/c...9980232089.pdf

 

And the review on powered approach speeds criteria from Nav Air provides a history of the development of the backside technique in chapter 2. Though the whole thing is worth the read.

http://www.dept.aoe.vt.edu/~durham/2002-71.pdf

 

Or this post.

 

Hook to ramp refers to the distance from the tip of the hook to aft section of the carrier runway.

 

 

Safety requirements say it should be no less than 10 feet. If hook to ramp distance is less than 10 feet there is a large risk of inadvertent engagement. Say if the ship heaves, for example. Hook to ramp distance is primarily a function of the distance from the hook touchdown to the ramp.

 

Hook to ramp distance can be adjusted by changing the basic angle of meatball. Lets look an actual carrier recovery bulletin used by LSO's.

 

 

CV 62 Independence stands out. The first thing to note about her is, that she can't recover aircraft using a 3 degree glide slope because the hook to ramp distance is less than 10 feet. This is because the three wire is located to close to the ramp. Since it’s based on right triangles, we can mathematically prove it.

 

CV 62 Hook touchdown point = 185 feet forward of the ramp

Tan of 3.0 = Hook to Ramp clearance /185 (Hook Touchdown distance from ramp.)

Hook to ramp = 9.69

Thus you can never safely land aircraft via a 3 degree glide slope on the Independence.

 

To use a 3 degree glide slope on any carrier the hook touchdown point needs to be at least 191 feet forward of the ramp. As

Tan 3 = 10.009/191.

 

The Saratoga and the Forrestal are even worse, their touchdown point is only 178 feet from the stern.

 

The main concern with AOA on the approach is Hook to Eye Distance. Hook to Eye, is the distance from the pilots head to end of the arrestor hook. If we didn’t take this distance into account the hook would always land short of the target wire. Hook to Eye varies with each aircraft. Again lets look at a a real Aircraft Recovery Bulletin.

 

 

As we can see all aircraft have different hook to eye distances. Thus the meatball has to be adjusted for various aircraft types. In order to ensure each aircraft's tail hook lands half way between the 2 and 3 wire, on 4 wire boats.

 

The meatball’s angle is the basic angle + adjustment for hook to eye. So if hook to ramp clearance calls for a 3.5 degree glide slope, The meatball will set to angle of 3.5 and then moved up 16.70 feet if we’re recovering Hornets. So our actual glide slope is greater than 3.5.

 

What happens when your AOA is off is that hook to eye changes. Thus it compounds any flight path errors and leads to the hook either catching to soon or later.

 

 

Flow, I was just to model it for analysis but then i noticed that there was this part still attached to wing root. Just enough of parasitic drag to counter yaw tension. Wing was scissor cut upwards as there are traces of collision from starboard engine bottom up to wing root parallel to rudder fin that probablly saved plane from aft damage. collision speed contributed cleancut and removal of dangerous fuel mass from wing tank. possibly fatal leak was not continued from conformal one as if it did plane would for sure burst in flames. Guy was lucky as hell. That peace of flap kept fuel leak path away from entering afterburner zone by countering yaw as i said before. Any other case of midair wouldnt result this combo atleast in 1/mil cases. NASA's control surfaces reconfiguration is by my opinnion obsolete study but this conclusion opens a lot of possibilities in case max asymetric drag config. I still stand by my claims from beginning that complete loss of wing is fatal for plane, case is that wing was not lost in complete and that I havent read from either articles, HC video nor NASA. I said what I said, and I was probably wrong in some parts but pilot didn't told complete truth as it triggered my reaction and I didnt zoomed enough in pictures. I'm about to comit windtunnel test as it was my initial intention but with parasitic drag amount range instead of complete wing absence. This does not mean that DCS should give F15 that lucky strike so it allways flies rtb without wing. That odd is one in a million, not rule.

If you come up with simulations and wind tunnel testing, I’m all ears, that would actually be factual and worth discussing

As much as everyone keeps talking about the odds of this or that, you're all forgetting one very important aspect: DCS isn't real life. I don't mean that as 'it's a game', I mean that like this :

1. Real life pilots are well trained, competent, and safe (usually). DCS pilots are of highly variable skill level, definitely not safe, and very possibly drunk and/or stoned. Common activities include gems like striking street lights along Las Vegas main drag because you were breaking the sound barrier 10ft off the ground and didn't quite make the turn.

2. Real aircraft, barring major flare ups like WWII or Vietnam, rarely see combat against suitable near peer adversaries. In RL relatively few Eagles have ever been shot at, much less hit. In DCS probably tens of thousands have sustained battle damage.

Keeping those points in mind, 'once in a lifetime' situations suddenly become 'a normal Tuesday night'. You see a lot more one winged, badly damaged aircraft in a week online in DCS than every military in the world combined has had in the last twenty years. It makes a difference.