SinusoidDelta

Something resembling this: Edit to add: Stress strain curves won't tell us much about ultimate strength of a structure. Quote from this thread: http://www.pprune.org/archive/index.php/t-509868.html "What is written in a Flight Manual (FM) may not be a "true" (again, from my point of view) limit g-factor. I did see that in F-15 data. The baseline usage spectrum for F-15 assumes 2 exceedances of 100% limit load per 1000 FH. That is 8 exceedances per original service life of 4000 FH. An absolutely clear indication that this 100% limit load is not a maximum load encountered in a normal operation is the presence of a certain number of exceedances at around 110% of limit load. From the prospective of the FAA-type definition of the limit load, this is just a nonsense. In a test, the stress corresponding to the 100% limit load was 30 ksi gross. Net stress would be around 32 - 35 ksi. Therefore, the design ultimate stress is (32 - 35) x 1.5 = 48 - 52 ksi. For 7075-T73 aluminum alloy, the ultimate tensile strength is 71 ksi. Yield limit is 60 ksi. This means that when you pull F-15 to +9g you are nowhere close to the material strength or even yield limit (the design combat weight is assumed). This is partially what I called the distorted (can't hide there was some dramatization in my words) understanding of the structural issues among pilots."

If you read the paper it says exactly that, page 50.

Is there any mention that KBO is capable of IFF? The excerpt from the manual says it only provides range information.

I'd like to see that one day too. Players would quickly stop taking 3 bags and a missile on every hardpoint. In the mean time these people make great targets. The F-15 FM hits a brick wall pulling 14G and heavy. Does anyone know if tacview records G correctly? The OP's track didn't get over 12G according to tacview. 10+ G sustained for ~1.7 seconds. What gives?:noexpression:

I agree. Obviously it depends on the gross weight of the aircraft. In one of the threads droning endlessly about this subject I linked a very detailed and tragic description of an F-15A at Elmendorf that did infact violently rip its wings off. The pilot performed an abrupt pull up after a low, high speed pass just after take off. The jet was heavy, filled with fuel, wing tank and a full missile load out. Due to the complete destruction of the jet, and the wreckage landing in a river, no details were recovered regarding the speed or load factor seen in the pull up. The bottom line is this. The F-15 isn't indestructible. It isn't sculpted out of unobtanium. It is, however, capable of being pushed deep into overload territory. How far? That's the million dollar question. This sounds painfully obvious but it needs to be said; the F-15 is not the Su-27. They do not share the same mechanics of flight. The F-15 does not have the nose authority of the Su-27. Any sort of damage model is not going to be predicted and then implemented over night. Does the current lack of damage model afford eagle drivers an advantage? IMO not in any appreciable way. Once you pull 14G you're post stall maneuvering with near zero nose authority. Anyone doing this regularly, which is the argument here, will be killed many times. Even if you evade the first missile in this manner, you just solved the next missile's problem.

Correct, I misspoke there. The data came from signal data recorders installed into 1 out of 5 F-15's to determine service life. That same data was used in developing the OWS. FWIW the image below is from 105 flight hours of ONE F-15.

Mild overloads are more damaging to the crew chiefs than the airframe :megalol: In all seriousness, this has been discussed extensively elsewhere. I posted some of the OWS details I have. There are some situations where the airframe couldn't withstand a small overload such as a rolling pull-out, basically whenever the airframe is loaded asymmetrically. The other "danger zone quote is the transonic region where it becomes very easy to over G the jet. The F-15 wing went through a slight redesign during development. This was due to excessive wing loading and buffet in the transonic region. I have some charts I'll post later of flight test points that show 9G was exceeded far more than the McAir engineers wanted it to be.

??? You realize I'm strengthening your complaint, right? Missile performance is wrong for all missiles regardless of the country they were developed in. And as I've said before on this forum, I have no idea what the actual argument is here.

The missile lifetime should be set to 60 in order to be realistic. Unless I'm misunderstanding. Also, don't compare this to DarkFire's Aim-120C test. The 120C was not guided and thus is not a valid comparison. The first ER was subsonic 5nm off the target's nose and thus could not maneuver. That is a result of the guidance commanding the missile to maneuver immediately after leaving the rail and is the same behavior you'll see with a guided 120C and the rest of DarkFire's ER/ET tests. I graphed the missile flyout and attached the excel. The main thing I notice is the ET's higher drag in comparison to the ER. I think this is what GG predicted. In either case I see no reason to complain about the R-27's max speed. Its actually higher than I expected for a launch from 32 kft. The concern illustrated here is the effect of guidance on missile downrange distance. GG has said ED is aware of this and working on a solution. In hindsight graphing Mach/Alt over downrange distance would have made a much better illustration. I'm too lazy at the moment. Perhaps someone else can look into it? :music_whistling: DCS Missile Performance Graph.zip

I can't tell if you're being sarcastic or what you're trying to imply Jun. There are two threads I linked below. I'd advise anyone interested in hacking out the math to check them out. They actually reference the missile analysis paper by IASGATG for some details. Page 2 of the keypub thread has an excellent excel spreadsheet for estimating missile maneuverability. http://www.f-16.net/forum/viewtopic.php?f=38&t=28234&sid=0215c897e75ab87672471eb940cf7c2a http://forum.keypublishing.com/showthread.php?137398-What-factors-affecting-aircraft-missiles-sustained-turn-rate

Roger that. TBH I don't have a grasp on how it's modeled now TBH. From watching the missile flyout in game it looks more like the missile is simply rotated about a point mass and less like a result of control surface deflection and resulting AoA. For those asking about CD0: zero-lift drag coefficient (i.e., drag coeffecient where lift equals zero for a certain configuration, α=0 or close to it)

Yep, just exported the telemetry csv and graphed it in excel. I can post the xlsx file once I get back to my PC if you'd like.

That's interesting. In the reading I've done the most common mathematical model for missile flight is skid-to-turn. STT models assume that the pitch and yaw planes have identical behavior. So when you say 'the whole turning thing' do you mean there were problems determining response/behavior for missile maneuvering in any axis?

I had a look at the acmi and plotted the flyout. The 120's flight path is good....when it's fired unguided. There is a very slight loft, basically level flight, and altitude drops off sharply below mach=1.5. Fire the 120 (or any missile, same conditions) with guidance and compare the result. It's as if the missile guidance/control is trying to bleed off as much energy as possible.

FWIW I think it might be possible to mod the stick or throttle using an Njoy32 control board and the Njoy32 Pro software. It would require a lot of reverse engineering.

My understanding is that 32 channel * 8 axes is a DirectX limitation for a single device.

The most interesting part is that "ALPHA" wasn't ran on a 3.2 Ghz desktop. It was ran on a $30 Raspberri Pi. http://magazine.uc.edu/editors_picks/recent_features/alpha.html

If anyone is really itching for a new grip, consider contacting these guys: Infinity Aerospace Custom Military-Style Stick Grips starting at $200... Be sure to read everything on their site. These are real-life aviation grips, customizable, left-hand and right-handed, also used in sims at Edwards AFB. If I were in the market I would've contacted them a long time ago.

No surprise there :megalol:

Some more details on the F/A-18 FCS can be found on page 4 of this paper. The key point (as Aaron described) is that longitudinal and lateral axes are almost always loaded independently. This principle is true for the F-15. The images below are from this NASA TM.

:shocking: Those amphenol connectors! Those would cost me a small fortune. My experience is on the civilian side. Specifically the automotive sector where measuring/defining customer efforts are a large part of the engineering process. Hence the reason I'm overly critical when judging components that may be somewhat trivial to most consumers.

I agree with you on the wiring. I was amazed to find masking tape haphazardly placed in the stick grip to control wire routing. I meant overall quality though. The switches and buttons have an unacceptable failure rate. We should create a poll to see how many TM Warthog owners have not had a switch fail. My first switch failed within four months of owning it. Whats worse is thrustmaster seems to have incorporated the high failure rate into their business model and will just send you another one of the clearly defective switches to install yourself..... on product that is still in warranty and you cost $400. As far as feeling/efforts IMO the switches are inconsistent. The warthog may be licensed by the USAF but not one of the switches are Mil-Spec. The 2-POS toggle switches on the throttle have way more snap than needed....they give off a sound like a bull whip. The left throttle toggle switch has almost zero snap and hangs all the time until it finally breaks. The cursor is a basically useless. The red left throttle button takes too much force to depress with your pinky. Any push button on the stick has the same story. They're all the same part with a different housing and they all wear out too fast. Sorry for the rant. And again, this is all just my opinion.

Like I said, it's a matter of opinion. I don't follow you on the flight dynamics argument. And the warthog switch are IMO very poor quality.

:DThat's a magnificent design. The Mamba doesn't quite have the real estate to work with inside the housing. You'd have to mount the spring/damper externally on the extension. I came across a calle Fibro that makes very compact gas filled dampers. Chexk out the 300mb PDF catalog. I believe the smallest is 67 mm max stroke. http://www.fibro.de/en/standard-parts/product-groups/f-springs-gas-springs.html?ga=0%3Ftype%3D100 Edit: I didn't say they were cheap :D

The F-16 has something like 1.5lb breakout on each axis. I don't see how that is even relevant here because it's (near as makes no difference) a fixed stick. Doesn't that make it self centering ;)? I also would argue that F–15 is self centering. The stick always returns to the same center position. The only time the stick will move from its hands off center position is if the pilot commands trim. There is a breakout force from the dead band (or center position) of something like 7.5 N before any aircraft response. And of course there is never going to be a flight sim stick that's accurate to real life. My point is a stick should allow you to fly the simulated aircraft in a realistic manner. The warthog does not allow that IMO.