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darkhorizon11
09-25-2005, 08:45 PM
This is perhaps one of the least understood topics in this forum, except for those who fly in real life.

I really don't feel like explaining in it detail, if your unfamiliar any google search or private pilot book will explain it.

But I for one and glad were getting it. Theres going to be a lot of whining I can see it. Wahhhh I can't land my 109 or Wahhh I always smash the gear on my Mustang, but whatever.

If you want real, this is it, fix the stall/spin bug and we'll have ourselves a sim thats comparable to real life, beyond damage modeling and rate of climb and turn performance in specific aircraft.

Which leads me to another great irony, there are hundreds of pages of topics debating performances of aircraft. Some over a matter of a extra degree or rate of roll, or turn, or an extra few kilometers per hour which the author whines about to get the advantage in their favorite aircraft.

Yet basic aerodynamic concepts like ground effect (until now), what is a stall and spin?, and multi-engine aerodynamics are ignored totally.

Okay I'll stop whining, all in all I'm still excited for this new tweak to the flight model!

Hoorah to that, thanks Oleg! http://forums.ubi.com/images/smilies/25.gif

darkhorizon11
09-25-2005, 08:45 PM
This is perhaps one of the least understood topics in this forum, except for those who fly in real life.

I really don't feel like explaining in it detail, if your unfamiliar any google search or private pilot book will explain it.

But I for one and glad were getting it. Theres going to be a lot of whining I can see it. Wahhhh I can't land my 109 or Wahhh I always smash the gear on my Mustang, but whatever.

If you want real, this is it, fix the stall/spin bug and we'll have ourselves a sim thats comparable to real life, beyond damage modeling and rate of climb and turn performance in specific aircraft.

Which leads me to another great irony, there are hundreds of pages of topics debating performances of aircraft. Some over a matter of a extra degree or rate of roll, or turn, or an extra few kilometers per hour which the author whines about to get the advantage in their favorite aircraft.

Yet basic aerodynamic concepts like ground effect (until now), what is a stall and spin?, and multi-engine aerodynamics are ignored totally.

Okay I'll stop whining, all in all I'm still excited for this new tweak to the flight model!

Hoorah to that, thanks Oleg! http://forums.ubi.com/images/smilies/25.gif

wayno7777
09-25-2005, 08:52 PM
Dang it, I still can't get on the ground the right way so as it is....

FritzGryphon
09-25-2005, 09:08 PM
I don't think so. The ground effect will soften the FA-18 landings I like to do.

All those other things would probably be harder to change than just increasing ground effect. No comparison.

PBNA-Boosher
09-25-2005, 09:40 PM
Yes indeed, thank you Oleg!

Ground effect was one crucial aspect of flight missing from this sim, and it might be a big (and realistic) help to those of you guys who just couldn't get the landings right. Be aware that the landing characteristics of your plane will change now because of it, but here's what ground effect basically is:

When your aircraft is taking off, landing or flying at a very low altitude, approximately 1/2 the wingspan distance off the ground, a cushion of air builds up underneath the wings of your plane. This cushion of air produces a bit of extra lift which can keep your plane aloft as you adjust on the runway. It does occur, this is not false. If you've ever been on board an airliner, this is the reason why even that huge jet seems to float along the air 15 feet above the runway for a while before it even touches the ground.

F19_Ob
09-26-2005, 02:34 AM
Also remember that this was the first try with these new flight characteristics and we probably will have some tuning of some planes ahead. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Amazing that they still work on it for us.....

Vacillator
09-26-2005, 02:37 AM
What about the opposite effect I've sometimes noticed when I crash? At only a few metres altitude, the ground suddenly seems to switch on its tractor beam and slam me down. I can only see this at times like when I've bailed and am watching on external. Is it just my imagination or has anyone else seen it?

WOLFMondo
09-26-2005, 03:06 AM
Are you sure ground effect isn't modelled? How much effect would it have on a small single engined fighter? I don't know much about it but I can't imagine a small fighter would be able to compress the air underneath it much compared to an airliner.

ploughman
09-26-2005, 03:17 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Which leads me to another great irony, there are hundreds of pages of topics debating performances of aircraft. Some over a matter of a extra degree or rate of roll, or turn, or an extra few kilometers per hour which the author whines about to get the advantage in their favorite aircraft.

Yet basic aerodynamic concepts like ground effect (until now), what is a stall and spin?, and multi-engine aerodynamics are ignored totally. </div></BLOCKQUOTE>


I think you'll find the problem is the Il2 AEP/PF community is undermodelled. Although future patches and upgrades will continue to enhance the community it won't be until the release of the Battle of Britain - White Cliffs of Dover that a community capable of discussing all the points you mentioned is available. Untill then we just have to make do.

TX-EcoDragon
09-26-2005, 03:29 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WOLFMondo:
Are you sure ground effect isn't modelled? How much effect would it have on a small single engined fighter? I don't know much about it but I can't imagine a small fighter would be able to compress the air underneath it much compared to an airliner. </div></BLOCKQUOTE>

Ground effect is noticeable no matter the size or weight, if someone needs to see the proof of this (you should feel it though) glance at the airspeed indicator as you touchdown in a "full stall" landing. You will see that the indicated airspeed is a fair amount lower than it would be in the same configuration and weight at a higher altitude. The main factor that changes the character of ground effect is the height of the wing above the ground, relative to it's span. This is why a low wing aircraft will generally be more forgiving on landing than a similar high wing design of the same general size and span. . . the low wing has a slightly greater performance increase due to ground effect at comparable height above touchdown. Most people will enjoy this new addition I think . . . well, except those that carry too much speed into the flare, but for those that make three-point landings it should be a nice treat. It should also increase takeoff performance somewhat. The only downside, if it's even modeled, is that aft elevator authority decreases somewhat in ground effect, but given that the induced drag of the main wing decreases, and lift increases, it usually doesn't matter.

Here is an easy to read article that goes into it about 2/3 through: http://www.avweb.com/news/airman/185905-1.html

And: http://www.se-technology.com/wig/html/main.php?open=aero&code=0 (http://www.se-technology.com/wig/html/main.php?open=aero&amp;code=0)

Deadmeat313
09-26-2005, 03:48 AM
Vacillator, I think you are referring to the way the external camera stops descending with the plane at very low altitudes. The plane keeps going, so it seems to suddenly drop below sight momentarily as it hits the ground.

You get a similar effect in the opposite direction while watching an aircraft take off in external view. The plane seems to climb above sight level, but the view snaps back to it once it has reached a few metres height.

All of this is simply because the camera stops - and starts to twist to follow the plane - when it reaches zero altitude.

T.

nakamura_kenji
09-26-2005, 04:42 AM
russia make actul ground effect heavy transport air plane, ekrano plane is name think general type aircraft take advantage this effect

http://www.airbornegrafix.com/HistoricAircraft/Ekranoplans/KM-08_title2.jpg
http://www.airbornegrafix.com/HistoricAircraft/Ekranoplans/EP_16_KM08.jpg
http://www.airbornegrafix.com/HistoricAircraft/Ekranoplans/LUN_title1.jpg
http://www.airbornegrafix.com/HistoricAircraft/Ekranoplans/LUN_1_732.jpg
http://www.airbornegrafix.com/HistoricAircraft/Ekranoplans/EP_6.jpg

Vacillator
09-26-2005, 04:51 AM
Deadmeat - thanks, I'm sure you're right, makes more sense than a sudden acceleration into the ground http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

n_k - great pics, they are some awesome muthas!

Kuna15
09-26-2005, 09:09 AM
I thought they were abandoned these heavies? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
They are quite useless when flying over ground.
Nevertheless nice pics NK.

LeadSpitter_
09-26-2005, 09:24 AM
should two aircraft bumping at 2mph explode into nothing? should a plane be twice the size of trees and houses?

does perfect flat ground off runway bounce a plane 3 times it height like its got dr dre hydrolics?

gov is simply wrong just by seeing the engine off glide slopes of all aircraft, flap lift is standard and dont increase the last few feet near the ground which to me is gov. if they get glide slopes power off correct, same with dive speed gravity engine off maybe we will have fms remotely realistic to rw physics.

Owlsphone
09-26-2005, 09:34 AM
I just remember that one of the first things my instructor had me do was get a feel for ground effect.

Basically we would come in for a landing and my instructor asked me to let him know when we were on the ground. When I let him know what I thought was the ground, he explained ground effect and that we were actually just cruising on air 3 feet from the runway.

Next he wanted me to practice staying in ground effect. Let me tell you it wasn't hard. Think of ground effect as an invisible runway a few feet off the ground. We went down the entire runway in ground effect.

OD_79
09-26-2005, 10:00 AM
It's great to use in a glider! You can buzz the entire airfield at only 3 feet and not slow down or lose height, then pull up and land! Great fun!

OD.

falling-bird
09-26-2005, 10:59 AM
Er...Have I missed something? Is ground effect to be introduced to FB flight model?
Is this to do with the patch 4.02(or whatever) thing? http://forums.ubi.com/images/smilies/blink.gif

darkhorizon11
09-26-2005, 05:36 PM
Haha it was dangerous to post this because I knew someone would use the "cushion of air" phrase. There is NO cushion of air at all, the air does not bouce off the ground and hit the wing again.

Due to relative wind around the airfoil and the interruption of the ground to that airflow, induced drag is reduced much lower than when normally flying around.

Basically with less drag the aircraft is more efficient and will fly at slower airspeeds. Its nice for landing, but at the same token, many a pilot has had an accident went taking off, seeing that he's off the ground below Vr and then jerking the plane into the sky. He then ussually finds, to his dismay, that the plane is no longer able to create the same amount of lift and falls from the sky.

Ground effect affects all aircraft and is the opposite of what you guys might think. The larger the wingspan and aspect ratio (ratio of the chord to the span) the LESS affect ground effect has, and LESS float. Adversely, the smaller stubbier the wings the MORE ground effect, and the MORE float on landing.

Also ground effect starts to occur within one wingspan's hieght above the ground, however, its not noticable until within 1/2 wingspan altitude. On your private pilot checkride make sure you say 1 wingspan though not 1/2 or else you'll have to explain why in detail and you might get caught there.

The reason? Were decreasing induced drag in ground effect, which is a direct result of wingtip vortices which are also reduced in ground effect.

I'll stop there because its pretty hard explain effectively without a diagram to show this. But any other RL pilots in here will agree with me. I just hope Oleg knows this and can model this effectively and right.

And yeah Lead, theres many more problems, your just looking at the glass half empty view. At least with ground effect modeled were one step closer to the real thing! http://forums.ubi.com/images/smilies/25.gif

Tully__
09-26-2005, 09:31 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WOLFMondo:
Are you sure ground effect isn't modelled? How much effect would it have on a small single engined fighter? I don't know much about it but I can't imagine a small fighter would be able to compress the air underneath it much compared to an airliner. </div></BLOCKQUOTE>It has more effect on a small plane than a large one in many cases as the landing gear is shorter. Also more effect on low wing aircraft than on high wing and I'd guess more effect on tail draggers than tricycle gear aircraft.

It is not a function of wing area or weight, but of wing span. When you get less the 0.5 - 0.75 wingspans from the ground, the effect becomes very apparent in ANY aircraft.

P.S. Definitely not currently modelled (4.01/4.01m)

Tully__
09-26-2005, 09:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ploughman:
I think you'll find the problem is the Il2 AEP/PF community is undermodelled. Although future patches and upgrades will continue to enhance the community it won't be until the release of the Battle of Britain - White Cliffs of Dover that a community capable of discussing all the points you mentioned is available. Untill then we just have to make do. </div></BLOCKQUOTE>

The community as a whole will never be fully conversant with complex aerodynamic principles, though a good proportion of the community are capable of a "seat of the pants" feel for the topic. The technical aspects of it require too high a level of mathematics.

That being said, anyone of average intelligence who chooses to apply him or herself in the topic should be able to grasp the basics provided they read the right text. There's a lot of bunk written on the topic http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Aaron_GT
09-27-2005, 01:45 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">should two aircraft bumping at 2mph explode into nothing? should a plane be twice the size of trees and houses? </div></BLOCKQUOTE>

Many European houses are comparatively small. A typical UK universal plan semi detached house (A common design from 1920-60, neatly spanning WW2) is about 18 by 24 feet per half and about 30 feet to the roof apex. A P51 has a length of 32 feet and wing span of 37 - i.e. a bit less than 50% bigger than a UK semi detached half (there are some fully detached houses in the UK on the same plan which would be 18x24 feet in total). The houses prevalent in Eastern Europe in WW2 might have been even smaller which might mean that a P51 would be twice the size.