Just thinking, this is a tough crowd (DCS) for a funny reason

Hello,

My saitek rudder pedals broke on Saturday night, the input is now fixed at max left rudder though the pedals move normally. This means no DCS and especially no MiG-21 :(...!

Very sad because I LOVE flying that thing, tough to fly in all the right ways, amazing immersion, etc. But since I can't fly it I started looking around the forum at old posts and started thinking about things. I can become a bit too cerebral when I'm not too busy...

Anyway, I was thinking about the flight model, which feels very real to me and also somewhat forgiving for a high-performance fighter. Forgiving because I do REALLY stupid things in it sometimes, like applying max elevator input at 270 kph while flying ~10 feet above the runway. I can do this because if the airplane crashes, I can checkout the damage modeling, but if I manage to escape...I learn something.

Which brings me to my point: programming the EFM/PFM must be insanely difficult. Not only because aircraft behavior is mediated by so many unpredictable forces (effected by temperature, altitude, humidity, turbulence), but because there are probably lots of things that are not known about edge of/out of the envelope behavior.

The funny thing is that many of us ask for perfect fidelity in aircraft behavior (it's what I want), which is what DCS strives for. But then we operate the aircraft in totally unrealistic ways, like spending lots of time at super-critical AOA at low altitudes. Most pilots probably don't know much about how the aircraft handles under those conditions, because they are responsible human beings who are trying not to lose their lives or the aircraft. Currently, the LNS MiG-21Bis is in the remarkable position of having it's EFM programmed by someone who also actively flies the plane currently and therefore brings both his experience and actual telemetry from flights (can't get better than that), yet telemetry from insane conditions are not usually available. Many aircraft have telemetry data from their OpEval (or equivalent), but I doubt it covers the entire range.

I read A LOT of criticisms of the MiG-21's stall behavior, which actually seems kind of similar to the PFM of the Su-27. In that it is really hard to enter a conventional stall with the aircraft. These seems a common feature of delta wing aircraft and came as quite a surprise to early test pilots. Read down the operational part of this wikipedia article on the XF-92:

http://en.wikipedia.org/wiki/Convair_XF-92

It also matches an article that I found following the US evaluation of the MiG-21.

Google this and download the PDF: MAKING THE BEST OF MiG-21.pdf - World Affairs Board

It's interesting and matches our LNS MiG-21 well.

I went on this rant because I hope that most users appreciate that getting perfect behavior from a computer probably can't happen (for every possible situation) and realistic flight characteristics is best experienced with realistic operation (which I don't always have time for) and the unforseen insanity that the simulation allows us to try, may not be perfect. I'm just hoping everyone can be civil with their criticisms and not say dumb/mean things when something doesn't jive with their expectations, accurate or imperfect.

I'm a car guy and have enjoyed operating some interesting stuff. That said, if you asked me to weigh in on the proper yaw rate for a 1997 Viper GTS spinning freely on it's roof after flipping on soft grass...well, I might have to pass on that one. I have 3000 miles of experience in that car, but never tried that.

BTW, love the topics and people around here. Awesome things happening for aviation enthusiasts!

Have a good night,

Nick

Great post! Sorry about your pedals, my CH pro pedals act up every once in a while (cat hair gets on the sensors) which gets pretty annoying. DCS is so amazing, its hard to imagine flight simulation without it, I think some people lose perspective and start getting too critical even though their intent is to perfect DCS. I just want to thank ED, the thing parties and all you on the forums for such a wonderfull product and support!

Have you tried pulling those saiteks apart? Could be something quite easy to fix with a bit of cleaning or super glue.

nice post :)

Have you tried pulling those saiteks apart? Could be something quite easy to fix with a bit of cleaning or super glue.

Yes, I tried. I removed all of the screws from the baseplate, but found that the resistance adjustment knob has a separate release mechanism that I couldn't fathom at that moment. Plus, the pedals are only 3 months old and I'm hoping that some form of warranty will help. I figure that removing the screws at all may void the warranty and messing with the tensioner seemed a certain way to void it.

Hopefully, I'll hear back from Saitek soon. Something is now rattling around in there, so I think it's more than just dirty. Worst case, I'll get another set, but I'm annoyed at spending another $200 after 3 months of use. Might have to go easy on the next pair (didn't think I was being to hard on these :music_whistling: ).

-Nick

Nick, just get them fixed by the time the Tom comes, the world will be right then:smilewink:.

There are a few posts regarding Saitek pedals, just do a quick search for the full dismantling procedure.

I wouldn't hold out much hope for spares from Saitek however. But again, you may find some guys on the forum have an old set laying around.

Mine are shortly to be replaced with MFG Crosswinds, which are definitely a step forwards.

In the mean time I found out that differential braking really, really didn't work out in my car. I guess I played too much DCS:Mig-21bis lately :=)

If youre aiming for presision you gotta have a tough croud ;)

The others are playing WT or AceCombat :)

If youre aiming for presision you gotta have a tough croud ;)

 

The others are playing WT or AceCombat :)

Yes, I am a member of said crowd, but that was not the point of the post. :)

-Nick

great post - well said

(couldn't rep you)

Hello,

Which brings me to my point: programming the EFM/PFM must be insanely difficult. ....lots of things that are not known about edge of/out of the envelope behavior.

 

The funny thing is that many of us ask for perfect fidelity in aircraft behavior (it's what I want), which is what DCS strives for.

But then we operate the aircraft in totally unrealistic ways, like spending lots of time at super-critical AOA at low altitudes. Most pilots probably don't know much about how the aircraft handles under those conditions, because they are responsible human beings who are trying not to lose their lives or the aircraft.

 

......yet telemetry from insane conditions are not usually available. Many aircraft have telemetry data from their OpEval (or equivalent), but I doubt it covers the entire range.

 

I read A LOT of criticisms of the MiG-21's stall behavior, which actually seems kind of similar to the PFM of the Su-27. In that it is really hard to enter a conventional stall with the aircraft.

 

I went on this rant because I hope that most users appreciate that getting perfect behavior from a computer probably can't happen....

 

I'm just hoping everyone can be civil with their criticisms and not say dumb/mean things when something doesn't jive with their expectations, accurate or imperfect.

 

I'm a car guy and have enjoyed operating some interesting stuff. That said, if you asked me to weigh in on the proper yaw rate for a 1997 Viper GTS spinning freely on it's roof after flipping on soft grass...well, I might have to pass on that one. I have 3000 miles of experience in that car, but never tried that.

Nick

Hi,

Yes making an EFM/PFM is obviously not easy & I'm sure the majority of simmers realizes that.

Allot is known about "edge of the envelope behavior" & I doubt we ask much for realistic FM "out of the envelope behavior".

You are assuming that "we operate the aircraft in totally unrealistic ways, like spending lots of time at super-critical AOA at low altitudes" I don't think that's how we spend lots of our time. I think most time is spent in intercepts, AG, WVR guns dogfights & aerobatics.

What exactly do you mean by "totally unrealistic ways & insane conditions" & how can you put the 21 in those conditions? & what is "super-critical AOA"?

Pilots DO know how their plane handles over critical AOA (not at low altitudes, for obvious reasons). Exceeding critical AOA & knowing the airplanes limitations is a part of a pilots training...it's theirs job to know.

"insane conditions" I don't agree that people are asking about RL FM for those conditions. But normal conditions, like stalls, spins, flatspins, etc...yes! Also the test pilots have taken the bird trough an exhaustive test program, so there is surely enough of data.

I don't see "A LOT" of criticisms of the MiG-21's stall behavior.

Well you can stall the 21, it's not un-stallable.

AFAIK there was concerns about incorrect after stall behavior & with the new FM (2 patches ago) the stall caracteristics was greatly changed & some people want to know why such a big difference from the previous FM.

Perfect behavior from a computer probably can't happen....agreed but you can get pretty darn close! & even the simulators are evolving.

You don't have to worry, most of us are quite civil around here;) Without criticisms & questioning there would be no progress.

LN Mig-21 has rightfully received countless of positive reviews & "thank you" posts, for their hard work!

Your car comparison is funny :) & if you would ask me the same question about my airplane I would be clueless too...but frankly I can't see how it relates to the 21 or PFM discussion at all?

All in all, I think even the hardcore simmers are not demanding a PFM in ""totally unrealistic ways & insane conditions" But expecting a realistic FM within aircraft capability's is reasonable & doable, if you want to call it a PFM.

Thus I feel your rant is a little bit on the exaggerated side:smilewink:

Not even NASA can completely generate a simple computerized model predicting the aerodynamic forces on an aircraft for any given state the aircraft can achieve. Subsonic, steady state conditions (i.e. straight and level flight, sustained climb, flat steady state turns, etc.) lend themselves to mathematical modeling much better than dynamic situations but even those can be complicated by a number of factors.

Performance charts and pilot manual guidelines don't even begin to give you enough information to make a reasonably accurate flight model. Wind tunnel data can help, but the best information is empirically measured by heavily instrumented flight testing. Very little data of this nature is available and even when it is, it is not complete enough to cover the aircraft's full range of attitude, speed, and altitude.

So, anybody doing flight modeling is going to have to generate some basic lift, drag, and inertia coupling values based on known conditions and previous experience with other aircraft, then use some trial and error to fudge these values to produce results similar to published performance charts.

Imagine that as an aircraft pulls AoA, that the airflow doesn't follow simple linear algebra. Imagine that the location of the wing/engines/tail causes unpredictable interference that varies greatly with angle of attack and sideslip angle. The people doing the flight modeling either have to ignore such effects or make some educated guesses on what these effects would be and how to account for them...

Then throw in compressibility and supersonic shockwaves.

Like a lot of people who are flying DCS aircraft, I want the most realistic FMs possible. But I fully realize what it takes to even get them halfway right, so I can forgive minor variances and just hope that the major glitches can be identified and corrected without breaking something else.

Hi,

Thus I feel your rant is a little bit on the exaggerated side:smilewink:

What good is a rant if you don't exaggerate? ;)

-Nick

Flight models are a P.I.A. for sure. My poor OV-10 would have been a gate guard in Strike Fighters if not for Column5's help. :)

Great post! Sorry about your pedals, my CH pro pedals act up every once in a while (cat hair gets on the sensors) which gets pretty annoying. DCS is so amazing, its hard to imagine flight simulation without it, I think some people lose perspective and start getting too critical even though their intent is to perfect DCS. I just want to thank ED, the thing parties and all you on the forums for such a wonderfull product and support!

CH Hangar forums has a how-to to disassemble the Pro Pedals to R&R them.

http://www.ch-hangar.com/forum/index.php/files/file/317-ch-products-pro-pedals-disassembly-guide/

(re: Message #1)

I think you may have read this, as to exploring the jet's performance concerning outer envelope boundaries. It is referenced within Chuck's Mig-21bis Guide:

https://drive.google.com/file/d/0B-uSpZROuEd3SlphQlItbWJLRm8/edit?pli=1

Did a search to Wikipedia for the US version YF-110, but this was the result:

https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21

Google'd YF-110:

https://www.google.com/search?q=YF-110&ie=utf-8&oe=utf-8

https://en.wikipedia.org/wiki/4477th_Test_and_Evaluation_Squadron

Yeah, let's jury-rig the Su-25's flare dispenser...

http://aviationweek.com/blog/we-didn-t-know-what-90-percent-switches-did

I am purely speculating, me not being an aerodynamics engineer or a flight systems modeler, but in DCSW using the Mig-21bis, forcing extreme maneuvers, will the flight model here allow extreme maneuvers without being restricted within its modeling? I can easily force flameout in a few particular experiments, no problem. But will forcing extreme AOA allow positive recovery results as discussed above in the readings and video?

Good excuse to order MFG crosswinds.

You speak truth in your post, my friend. Sometimes this community seems a bit obsessive over the flight model stuff, which is understandable because we DO want realism, yet we forget what an accomplishment the modules we have are.

The MiG 21 is EXCELLENT. I had the rare honor of having a friend of my father, who happened to be a immigrant from the former Yugoslavia (which is a pretty awesome story in itself) and a former MiG 21 aviator try my sim setup. He was completely floored by the realism in LNS module. When I see this gentleman again I am going to make a youtube video with his impressions, if he is willing, and post a link here on the forum. Pretty awesome to hear it from someone who was in the real steel!

From what he told me, the stall behavior on the MiG is modeled very very well, along with the instant and sustained turn rate, and he raved over the landing characteristics as well.

You speak truth in your post, my friend. Sometimes this community seems a bit obsessive over the flight model stuff, which is understandable because we DO want realism, yet we forget what an accomplishment the modules we have are.

 

The MiG 21 is EXCELLENT. I had the rare honor of having a friend of my father, who happened to be a immigrant from the former Yugoslavia (which is a pretty awesome story in itself) and a former MiG 21 aviator try my sim setup. He was completely floored by the realism in LNS module. When I see this gentleman again I am going to make a youtube video with his impressions, if he is willing, and post a link here on the forum. Pretty awesome to hear it from someone who was in the real steel!

 

From what he told me, the stall behavior on the MiG is modeled very very well, along with the instant and sustained turn rate, and he raved over the landing characteristics as well.

That is incredible. Yes absolutely get his impressions. And ****ing throw in anecdotes or stories while flying! I'd love to hear anything he might have to say. :)