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p-11.cAce
07-26-2010, 08:35 AM
I have been thinking of adding a self-launch endorsement to my glider rating so last Friday I took a flight in an HK-36 motor glider. I'm pretty used to large amounts of adverse yaw in our club ASK-21 but the HK felt ridiculous. Part of this was due to the seating position - unlike the ASK where you are a few feet forward of the spar, in the HK your back is literally against the it. This really magnifies any yawing motion as it feels like you are twisting side to side on a bar stool!

So in un-accelerated level flight in the HK if you push the stick left the first thing that happens is the nose skates off to the right - not a little bit, I'm talking 15+ degrees of yaw - and then the left wing lowers a bit as you enter a slipping turn. The nose starts to drop, airspeed picks up - but with so little vertical surface on the fuselage and so much leverage from the ailerons way out there it's happier just sitting in the slip instead of weathervaning around. On initial climb with p-factor, torque, slipstream, and the usual low level bumps tossed in it can be a pretty interesting ride. Basically you have to adjust to the fact that if a wing drops you have to put in a bunch of rudder and a little bit of aileron if you want to hold your heading.

So on initial climb I was doing this silly little dance: left wing drops - push stick right- nose goes left - kick right rudder - right wing drops - push stick left - nose skates right across heading - left wing drops and we oscillate around to the amusement of my instructor. So he says "I basically only use the ailerons to keep from over banking in turns - other than that don't move the stick much side to side". I stop chasing the stick around, pick up my low wing with rudder, and the oscillations stop.

After that things were pretty normal except for steep turns - LOTS of left rudder - wait - a little bit of left stick to get it rolling - wait - back stick to keep our speed stable - and then "catch" the bank angle with quite a bit of right stick. This brings up another fun little problem with the HK (and all sailplanes) - they really LOVE to spiral. You see when you put in that opposite stick to keep from over banking, the adverse yaw adds to the yawing force. If you keep in the same amount of rudder the nose moves further right then starts to drop, you pull back more to keep your speed, the inside wing slows more and drops further so you add more opposite stick which adds more adverse yaw - see where this is going? Keep that up at low speed and eventually you run out of elevator and diverge into some really bad attitude - usually spinning on your back - or at high speed and you pull the wings off.

OK so what does all this have to do with IL2 FM's? Mostly it's my own wonder at what the reaction would be to flying this aircraft in IL2 with a realistic FM would be. In a non-training simulation should the FM's be as realistic as possible (which may fly in the face of what the average sim pilot expects) or should they "fit" what the average non-pilot sim flyer expects? I would love to discuss this in as civil a manner as possible - I really find the divergence between sim flying and real flying fascinating http://forums.ubi.com/images/smilies/25.gif

Sillius_Sodus
07-26-2010, 09:49 AM
Hello p-11.cAce,

It sounds like you've been having fun with adverse yaw and other 'features' of irl flight http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif.

First off, some aircraft suffer from what you have described more than others. It might have been quite pronounced in some WWII aircraft, or not, depending on the talents of the designers.

As for computer flying, as long as we look at the world through a flat screen, it will be very difficult to have a true representation of an aircraft's fm. As you know, there is more to flying than just looking out the windscreen and I'm sure you felt and heard other things that helped you figure out what the plane was doing.

You can simulate these of course, but it will cost you $$$. For example, modern simulators for aircraft like, say, the Boeing 777 or Airbus 320 are accurate enough that a pilot does not need to practice in a real one in order to become rated in it. Of course those simulators can cost somewhere north of $20 million...

In a game like IL2, I don't think super accurate flight models are a make or break issue. As long as the fm's are 'in the ballpark' relative to each other, I won't complain......too much... http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

Bremspropeller
07-26-2010, 10:09 AM
Well, the use of customization-options such as "easy", "medium" and "hard" should adjust the FM accordingly between newbies and die-hard FM-maniacs.

Generally, the more accurate you want to have it, the harder it gets to simulate the aircraft - especially when trying to simulate the extreme corners of the flight-envelope (even Level-D sims aren't very accurate close to stalling or spinning).

Consequently, you'll have to have a point where "the ballpark" is close enough for you to intersect the "reality"-graph with the "costs"-graph.

IL-2 is doing a great job for a 2001-game, but other Sims (X-Plane !) have shown what's possible and where flight-simulation should be heading in the future.

p-11.cAce
07-26-2010, 10:17 AM
Brem how would you compare the table-based FM's of FSX to x-plane? Is x-plane still using (i can't remember what it's called exactly) some form of real time calculations in the FM? Is IL2 table based?

BillSwagger
07-26-2010, 11:28 AM
Originally posted by p-11.cAce:
In a non-training simulation should the FM's be as realistic as possible (which may fly in the face of what the average sim pilot expects) or should they "fit" what the average non-pilot sim flyer expects? I would love to discuss this in as civil a manner as possible - I really find the divergence between sim flying and real flying fascinating http://forums.ubi.com/images/smilies/25.gif

I always like hearing what real pilots have to say about flight sims. I'd hope to have a sim that mimics the actual performance of the aircraft, realizing that not all behaviors are going to be as accurate, but it seems with todays advancements in computer tech that it could actually get pretty close.
I fly Il2 with the expectation of having a realistic combat sim experience. I don't fly Il2 with the expectation of "feeling" like I'm flying a plane, although some FMs do a good job of that. That is to say, that i fly it because i enjoy the combat part of it more so than just doing loops or flying around looking at trees. More realism is always better.





Bill

Bremspropeller
07-26-2010, 12:28 PM
Well, it's pretty much dependant on the plane you're asessing in FSX.
I can fly a Cessna (Payware!) into what would it cause to wingdrop on it's back in X-Plane, yet it only "locks in" and won't violently roll over.

X-Plane is a lot more like IL2 (feeling-wise), but the FMs don't differ that much (quality-wise), as they're not table-based, but they're computed in real-time (Blade Element Theory).
Therefore, the flight-model is pretty much based on the quality of your 3d-model.

X-Plane also simulates a lot of neat stuff by default (Carburator Icing, Inverted Carburator Cut-Out, wing- and propwash, etc)

There is a simhq-review of X-Plane 9 on Youtube.

Part 1:
http://www.youtube.com/watch?v...PgVM&feature=related (http://www.youtube.com/watch?v=23H_Kn1PgVM&feature=related)

Part 2:
http://www.youtube.com/watch?v=07YKgNGPmaU

Having a warbird-sim based on Blade Element Theory would be a really cool one. http://forums.ubi.com/images/smilies/25.gif

JFA2
07-26-2010, 12:41 PM
Gliders need more foot in turns because of longer wings.-> Ailerons are located at the top end of the wing and generates more opposite yaw. In my experience there are differences between gliders in this matter and with other "fm" also. Theres same issue with motor aircrafts but opposite yaw is normally smaller. Il2 is doing quite nice job simulating flying in general but im sure that first thing simpilot would notice is the amount of rudder needed in turns. The ball would be slipping (late) all the time.

I am also realism freak and hope that SOW introduces more accurate fms. Use of rudder and stick to make an aircraft fly clean should make a big difference -also in scoreboard.

M_Gunz
07-26-2010, 12:46 PM
Originally posted by p-11.cAce:
So in un-accelerated level flight in the HK if you push the stick left the first thing that happens is the nose skates off to the right - not a little bit, I'm talking 15+ degrees of yaw - and then the left wing lowers a bit as you enter a slipping turn. The nose starts to drop, airspeed picks up - but with so little vertical surface on the fuselage and so much leverage from the ailerons way out there it's happier just sitting in the slip instead of weathervaning around. On initial climb with p-factor, torque, slipstream, and the usual low level bumps tossed in it can be a pretty interesting ride. Basically you have to adjust to the fact that if a wing drops you have to put in a bunch of rudder and a little bit of aileron if you want to hold your heading.

So on initial climb I was doing this silly little dance: left wing drops - push stick right- nose goes left - kick right rudder - right wing drops - push stick left - nose skates right across heading - left wing drops and we oscillate around to the amusement of my instructor. So he says "I basically only use the ailerons to keep from over banking in turns - other than that don't move the stick much side to side". I stop chasing the stick around, pick up my low wing with rudder, and the oscillations stop.

After that things were pretty normal except for steep turns - LOTS of left rudder - wait - a little bit of left stick to get it rolling - wait - back stick to keep our speed stable - and then "catch" the bank angle with quite a bit of right stick.

Does it remind you of 4.01 only worse?

p-11.cAce
07-26-2010, 01:19 PM
Does it remind you of 4.01 only worse?

lol - I was a fan of the "hard" fm before it was "dumbed down". I guess the point I'm trying to make is that airplanes do somewhat "odd" things in RL that would, I'm guessing, lead a sim only pilot to think the FM was wrong or broken. Being in a steep left bank and having the nose go even further left when you put in right stick would, I think, give a sim pilot pause.

M_Gunz
07-26-2010, 01:41 PM
Oh I agree with you and if anything I think that 4.01 is tame compared to what you go through with that glider.
We're used to sims that don't model all effects, in fact AFAIK there have been none for the PC at all.

You describe the glider: but with so little vertical surface on the fuselage and so much leverage from the ailerons way out there

Perhaps some of the stability changes in IL2 come from varying the amount or even sim mechanics by which the fuselage affects flight forces? What we have now does seem better rather than just dumbed down, you can fly knife edge with nose up and it seems you get some lift from the fuselage without being able to exploit that to the extreme. Hard to tell what is modeled and what not though get into an unusual attitude and a missing factor may become 'big' in absence as it were.

p-11.cAce
07-26-2010, 01:48 PM
though get into an unusual attitude and a missing factor may become 'big' in absence as it were.

Agree 100%. I really enjoy flying at the limits of the current FM, especially in low speed high alpha turn fights with early war aircraft. BnZ has its thrills, but to me nothing is more satisfying than eeking out that last bit of turn performance to get in behind someone.

Bremspropeller
07-26-2010, 01:52 PM
I wonder how this thing flew in IL2 or FS http://forums.ubi.com/images/smilies/59.gif

http://www.ebaumsworld.com/video/watch/720438/

p-11.cAce
07-26-2010, 01:57 PM
I wonder how this thing flew in IL2 or FS

I'd say it's L/D is seriously overmodelled http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

M_Gunz
07-26-2010, 04:03 PM
Originally posted by Bremspropeller:
I wonder how this thing flew in IL2 or FS http://forums.ubi.com/images/smilies/59.gif

http://www.ebaumsworld.com/video/watch/720438/

Mods....

WTE_Galway
07-26-2010, 05:36 PM
Originally posted by p-11.cAce:
OK so what does all this have to do with IL2 FM's? Mostly it's my own wonder at what the reaction would be to flying this aircraft in IL2 with a realistic FM would be. In a non-training simulation should the FM's be as realistic as possible (which may fly in the face of what the average sim pilot expects) or should they "fit" what the average non-pilot sim flyer expects? I would love to discuss this in as civil a manner as possible - I really find the divergence between sim flying and real flying fascinating http://forums.ubi.com/images/smilies/25.gif

My observation is that, at least for online gamer types, a "better" FM is not usually a more accurate one, its the one that gives you the edge.

How often do you see posts extolling the virtues of some new modded FM followed by a rave about how much it IMPROVES the aircraft's performance in combat. I have yet to see a post that starts "the modded XXXX flight model is awesome finally bringing us all the real flaws that made this aircraft a total dog below 5000' and a complete b@itch to land.

Basically for "gamers" as opposed to "sim flyers" a better FM = a higher performance FM.

Personally, for me, the more realistic the better http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

FoolTrottel
07-26-2010, 11:26 PM
Originally posted by WTE_Galway
(...) I have yet to see a post that starts "the modded XXXX flight model is awesome finally bringing us all the real flaws that made this aircraft a total dog below 5000' and a complete b@itch to land.(...)
Any post like that is likely to be (re)moved or edited by a moderator, as it would be a violation of the rules around here: No FM/DM/WEPS discussions on mods remember?

julian265
07-27-2010, 12:54 AM
Originally posted by p-11.cAce:
I have been thinking of adding a self-launch endorsement to my glider rating so last Friday I took a flight in an HK-36 motor glider....

Have you got Rise of Flight? Have a go of the Camel if so - the gyro effect of the rotary in that plane is great (or hideous!)

p-11.cAce
07-27-2010, 06:22 AM
Have you got Rise of Flight? Have a go of the Camel if so - the gyro effect of the rotary in that plane is great (or hideous!)

I do have RoF and really enjoy flying it - though I spend almost all my time in a Pfalz http://forums.ubi.com/images/smilies/winky.gif

Daiichidoku
07-27-2010, 08:21 AM
Originally posted by Bremspropeller:
I wonder how this thing flew in IL2 or FS http://forums.ubi.com/images/smilies/59.gif

http://www.ebaumsworld.com/video/watch/720438/

no need to wonder, try the lurch http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif