SinusoidDelta

I said I didn't think it could. I admitted I was wrong. You win. We're getting nowhere here, like most every thread on this forum. The Su-27 is extremely vulnerable in the transonic region, the eagle is not. Each aircraft is not going to exhibit the same failure mode or design limitation. I don't know what either aircrafts' failure mode should be. We could attempt a discussion from an engineering based approach or everyone can continue slinging mud.

Yes, landing is not recommended if the 90° Crosswind component exceeds 30 knots. If the Crosswind component exceeds 25 knots, do not exceed 10° pitch. Hold the crab through touchdown and use rudder to maintain runway track, use the aileron into the wind to maintain wings level attitude. If directional control becomes difficult lower the nose and brake in a three point attitude.

What's your mach there when breaking the wings off? My math could be wrong but it looks like you're smack dab in the middle of the transonic trap. Are you pulling 9G at ~mach 1.00 in a bank? Because that's how you rip the wings off.

Maybe I'm misinterpreting you but the -1 says to maintain the crab until touchdown. Unfortunately it doesn't give any information about crosswind controls on taxi/takeoff roll.

NWS should disengage above 80 knots. It should disable when the front strut is extended and ARI should disengage at wheel spin up.

I stand corrected. How long did it sustain 17G for? I'll have to try it out although flying with 3 bags is likely to get you killed by the enemy before you rip your jet apart.

I've can't even pull 14G in the eagle. Is it even possible supersonic to pull that many G with three bags with our F-15 FM? I don't think so. The F-15 is capable of extreme overloading without exceeding ultimate strength. We can't even over-g the f-15 to the extent that should be possible. Consider attempting to simulate what structural members might yield and what plastic deformation would result, simulating the resultant deformation's aerodynamics effects...it becomes an absurdly complicated task.It's unfortunate that the published Su-27 flight manual has laid out overload limits and complete structural failure is the only result but that's how it is..... Until ED gets first-hand information to the contrary we know it's not gonna change.

I guess you didn't see the code commented out saying, "This portion not intended for user modification".

I did read it? I wasn't meaning to be condescending. Flankers post doesn't translate well, I don't know what he's saying.

I can't say I didn't see that coming Yoda :( I wish your mod could be ported and displayed on the MFD in the F-15. It really is that good.

Help out with what? I don't think many people realize the level and frequency of actual technical discussions that occur on the 'other side' of the forum. The English forum could learn a lot from them.

The magazine article is direct from an eagle pilot. It really bothers me that in order to be believe your knowledge must be posteriori when we actually know the behavior is wrong.

Right, you should be able to pull through the AOA limiter with 7lbs of force or something but that is modeled as the W key. Also, not all materials bend (much) before they break. High G high AOA with sudden aileron input wouldn't give a warning aside from a loud bang alerting the pilot he will likely perish in a death spiral before ejecting. If the FBW limited input to the actual printed overload figures, flanker drivers would be much more upset.

Do you mean the S key for maneuvering range? You can't turn NWS off afaik in DCS or RL. @svend You're right ARI should be disengaged on takeoff and landing, not modeled currently. It's hard to find data as to what CAS should be doing with wheels on the ground during takeoff roll. Edit: Just found this, definitely read: [ame=https://www.flightglobal.com/FlightPDFArchive/1973/1973%20-%202800.PDF]http://https://www.flightglobal.com/FlightPDFArchive/1973/1973%20-%202800.PDF[/ame]

I'm not really following your logic at all. Let's assume the nose wheel is fixed and aligned with the runway. There is a crosswind perpendicular to the runway heading. The fuselage will block airflow to the downwind wing thus producing less lift than the windward wing. This would result in a rolling moment in the direction of the downwind. The fuselage will also generate a side force in the direction of the wind. I assume the same would be true to the downwind vertical stab/rudder and stabilator. The effect on the vertical stab would create a rolling moment as well. So you apply crosswind controls....use the rudder to stay on centerline and use aileron in to the crosswind to keep the wing from dropping. The F-15 has a strong dihedral though and it will really get away from you in DCS if there is a realistically heavy crosswind. None of this explains why a 20 knot taxi speed results in the jet being pushed off the centerline like it's made of styrofoam. The pilot should have to make minor corrections during the takeoff roll but it seems logical that CAS should be compensating to maintain commanded heading and roll.

You have a copy of the -34-1-3? How'd you get that?

I'm not questioning if the flanker is more or less susceptible than the eagle. I'm questioning if it is accurate. I'll post a track but I'm just trying to have a discussion.

Exactly. Slightly OT here but a crew chief I spoke to told me about an argument between some viper pilots and eagle drivers at the bar. The viper guys were bragging how superior their turn rate was on the deck. One of the eagle drivers said something like, "and I'd be able to shoot you down 6 times in that turn before you knew I was there". Then another eagle driver chimed in "You know what's the same about Doritos and F-16s? Crunch a bunch of em up and they'll just keep making more." All the metrics are a fun to compare. But IRL the objective isn't to have a fair fight, 'fly with a slide rule' in a romantic BFM turning fight. Come in fast, keep the mach up, smack them in the face and get out. Slats wouldn't really be a benefit to the Eagle's role.

I've said before, NWS is always engaged in the F-15 while the front strut is compressed. NWS has high and low gain settings, that's it. There should be no need to flip a switch during the takeoff roll. And again we aren't talking about taking off in a hurricane or even a 30 knot crosswind. We're talking about crosswinds on the order of pleasant breeze at 7 knots.

No ones signed up for the silent eagle AFAIK. Boeing needs something to keep the F-15 assembly line running after the F-15SA. I think the cheaper solution would be build a few more F-15SA's for the US arsenal. Boeing already did the legwork in developing a completely new FBW system and the new GE engines put out way more thrust than the older PW's. 16 Slammers is pretty sweet too. Spray some RAM on it and its a more affordable supplement to our air superiority concerns. Just my 2 cents.

I wish I had more to data to provide other than it doesn't feel right. Maybe I just missed the memo regarding disengage NWS, I'll look into that. I just don't see how a 7 knot crosswind can push a 50,000 lb jet that's rolling at 20 knots off the centerline.

Jeeze come on frostie, I'm not that bad of a virtual pilot:smilewink:. It's not unintended asymmetric thrust causing the issue either. Have you tried taking off in the eagle with a crosswind frostie?

I'm glad you brought this up. There was another thread about it that fizzled out. The VA server always has a crosswind. The last time I flew it was 4 m/s which is roughly 7 knots. I definitely think there is an FM issue here. The F-15 will start veering even when taxiiing at 20 knots. I've read the F-15 is capable of taking off with a 40 knot crosswind.

Allegedly the great John Boyd wanted the F-15 to have slats for high G maneuvering during development. He also wanted to limit the F-15 limited ~5.5G as that was the most efficient point he determined through his EM wizardry.. Obviously neither of those considerations were honored. McAir believed slats added too much complexity (and weight I'd imagine) whereas the conical taper wing added a small amount of drag but takeoff distances were acceptable and this design allowed the F-15 to be extremely maneuverable in the transonic region. The same can't be said about the flanker. The F-14 was also being developed so their wasn't much benefit in developing a carrier capable F-15.

The Mig-25 looks like it was sculpted with an axe. The F-15 is very refined despite being designed maybe 20 years earlier than the Su-27? The Eagles negative camber at the wing tips, the sawtooth cutouts on the horizontal stabilizers, the inlet ramps, the vertical stabs have the surface area of an entire F-16. The Su-27 does have fancy lift augmentation devices, slats, flaperons, fixed inlets that look suspiciously similar to the F-14....Both the flanker and eagle are capable of things the other is not capable of and their shapes reflect that. I mean, formula 1 cars are quite hideous. Especially the latest season.... But they are designed for one purpose much like a fighter jet.