Ground effect?

[ladlon]

Quick question.... Sometimes, when I'm getting close to the ground, during a landing, the plane will suddenly bank into an inescapable roll, and plummet into the ground.

 

Is this some sort of ground turbulence effect, or perhaps I'm going to fast with my gear down, and it eventually causes some sort of aerodynamic failure, or something else?

[Kling]

sounds like a proper slow speed stall. If stalls are ever likely to occur  it would be just before touch down. some ww2 fighters had nasty stall characteristics...

 

The tip is to have a slightly higher landing speed.

The British were trained to land with all three wheels touching the ground at the same time. (with a nose up attitude i.e just before stall) 

The Americans however, to my knowledge prefered two point landing i.e the main wheels touch the ground and as speed comes down, so does the tail.

Edited February 28, 2019 by Kling

[AndyJWest]

Yup, agree with Kling. The only thing that would cause a sudden roll during landing approach would be a stall. Ground effect certainly wouldn't, and turbulence shouldn't be an issue unless you are too slow. Try recording your landings, and playing back any you have trouble in to see if you can find the problem. Most likely you are simply flying too slow, or using excessive control movements.

[ladlon]

Wouldn't a stall be a forward dip?... or IS it, but the torque from the prop causes the roll?  Just curious...

 

I'd have to test it further, but it SEEMS like it's when I'm getting (relatively) close to the ground... and seems to be related to the gear being down.

 

Obviously, lowering the gear while flying fast is going to cause drag and stuff, but I'm curious if it also causes instability (resulting in the roll spin).  It feels similar to putting the flaps down overspeed... things get bent, and you end up in a spinning roll.  Wasn't sure if the same kind of 'damage' and behavior happens putting the gear down overspeed.  Thing is, it doesn't seem to happen right away... so, I'm not sure if the delayed response (spin) is due to the gear 'slowly' getting damaged, and becoming an aerodynamic issue (just like having one flap stuck downwards)... or if it's actually the result of proximity to the ground (where you get a sort of turbulence ground effect).

 

It's all good and all...  I'm just curious what is being simulated there, that is causing that.

 

 

@AndyWest: Ah, you snuck in while I was typing.  Yep, I'm sure you guys are totally right.  Probably am going in to slow.  I have to make adjustments to my methods, since I'm coming from X-Plane, and flying a Baron or B-25!  I noticed that (at least in my sessions) it seems hard (for me at least) to actually 'drift' down.. and I always feel like I'm coming in for landing way too fast.  Probably have to get used to it... as well as actually check the landing speeds, etc.  I think they are FAR faster than general aviation planes.

 

Yep, not a complaint or thinking something is wrong... Just curious.  I've always loved the feel of the IL2 series... I get the sense of wind going around the wings, and a general 'on the edge of control' feeling, with the plane often slipping and sliding... as opposed to being on a rail, like some other sims.

 

Ya, I'll try a recording, and see what's going on there.  Thanks, guys.

 

Edited February 28, 2019 by ladlon

[Kling]

2 minutes ago, ladlon said:

Wouldn't a stall be a forward dip?... or IS it, but the torque from the prop causes the roll?  Just curious...

 

I'd have to test it further, but it SEEMS like it's when I'm getting (relatively) close to the ground... and seems to be related to the gear being down.

 

Obviously, lowering the gear while flying fast is going to cause drag and stuff, but I'm curious if it also causes instability (resulting in the roll spin).  It feels similar to putting the flaps down overspeed... things get bent, and you end up in a spinning roll.  Wasn't sure if the same kind of 'damage' and behavior happens putting the gear down overspeed.  Thing is, it doesn't seem to happen right away... so, I'm not sure if the delayed response (spin) is due to the gear 'slowly' getting damaged, and becoming an aerodynamic issue (just like having one flap stuck downwards)... or if it's actually the result of proximity to the ground (where you get a sort of turbulence ground effect).

 

It's all good and all...  I'm just curious what is being simulated there, that is causing that.

Stall can very often be one wing losing lift before the other. Had you been higher up it would most likely have developed a spin, now you just just hit the ground hard instead as you about to land.

Here check the first 10 secs of this video out. Even a pilot friendly aircraft as the Cessna 152 enters a snap stall if one wing stalls before the other

 

[ladlon]

Wow, I bet he gave any people in the parking lot below a bit of a scare!  That must have been some fun G's for him, as well...

 

Ya, I actually got myself into a bit of a death spin during a mission last night.  I had plenty of altitude, so I thought to myself, 'Okay, no problem... just let the stick center, throttle down, get some airpseed, and gently pull out....

 

Nope.

 

Then I started thinking (as my altitude continued to plummet), 'Okay, this is unexpected...  Is this a flat spin?...  Kind of looks like it, from what I can tell...  You can't get out of those, can you?...', and then I tried banking into the turn, then with the turn, playing with the rudders, etc...  I did finally manage to get it nose down, but could not pull up level...  'This is very peculiar...', I thought to myself, as the ground got closer and closer, 'Why can't I pull out of this?'...  Eventually, with only a bit of room left between me and someone's field, I discovered that I actually needed to throttle up a bit (...I was throttled full down, figuring I shouldn't be increasing the speed I was going downwards!), and with that, I was able to pull up.  Bit odd (to me anyway), but whatever...  I don't claim to be an expert in WW2 era airplanes!.... (or any airplanes, for that matter)

 

Yep, I'm probably obscenely way underspeed when approaching for a landing.  I know I'm certainly pulling hard on the stick to keep nose up (...like I said, I seem to have great trouble doing the 'drift in' thing... and am starting to think that WW2 planes don't do that!)  I'm used to 80-60mph(?) approaches, and I THINK (could be totally wrong) that these fighters are coming in at 100mph or more.  I've had all the IL2 sims, right down to the very first one... but never was in 'proper' control.  Sure, I could 'fly' and even land, but only this year, I've really started from the beginning, and tried to learn things properly (including following proper procedures)... starting with X-Plane, and in the last week or so, ClOD Blitz.  Things are definitely going better...

[ATAG_kiwiflieger]

Yep, the Spitfire and Hurricane approach speed is about 100-110 mph on final, slowing to 80-90 with full flaps down as you are touching down. The 109 at 110 are even faster than that due to the higher wingloading, their approach speeds are more like 200 km/h (125 mph). Also when recovering from a spin I find pushing the stick forward a bit to get the nose down quicker assists getting back to normal flight.

 

This link is for the Team Fusion wiki flight manuals, these list a number of useful figures and procedures for flying each aircraft: https://www.theairtacticalassaultgroup.com/wiki/doku.php?id=flight_manuals

[Buzzsaw]

Hello Ladlon

 

Actually if you are experiencing 'Ground Effect', you would be experiencing more lift and decreased drag, so it less likely you will stall.  This is an aerodynamic effect which is a function of the aircraft being closer to a fixed surface.

 

Questions:

 

Are you using flaps?  This will give you more lift at lower speeds as long as your wings are generally level.

 

Are you trimming your elevator to give more nose up after you deploy flaps and undercarriage?  Many types go nose down when the undercarriage is deployed.

 

If you are coming in at 60 mph, unless you are in a Tiger Moth, you are way too slow.

 

Approach speeds for the Spit/Hurri, (with flaps down) are approx. 100-110 mph, slowing to 80-90 mph after you cross the airfield boundary and touching the runway at approx. 80 mph.

 

For the 109/110, (again with flaps down) it is approx. 190-200 kmh approach, slowing to 150-160 kmh after you cross the boundary with the touch at approx. 150 kmh.

 

Be careful not to use your brakes until you are rolling straight and true and your tail wheel is firmly on the ground... and just light pumps of the brakes, don't jam them on or you will end up on your nose.

 

The key is you must 'fly' your aircraft into a landing... you are not just cutting your throttle completely and gliding in.  Your throttle should be engaged until the last second before you touch... you should be under control with the ability to add throttle and abort the landing and go around again if you need to.  That is why you need the flaps down 100%.... because they slow your aircraft and allow you to use your engine power without making the approach too fast.

 

Try dropping your flaps and undercarriage and flying around in at approach speeds under control as practice... so that means enough throttle to keep your speed at 120 mph for the Spits/Hurris and 200 kmh for the 109's/110's.  All turns should be very gentle.  (always drop the flaps before the undercarriage)

[56RAF_Roblex]

11 hours ago, ladlon said:

, I seem to have great trouble doing the 'drift in' thing...

 

The general idea when you are still learning is to pull out of your approach (AKA 'flare) flying parallel to the runway and and few feet up while still having *just* enough speed to almost maintain your altitude with your nose slightly raised then as the speed decays you will sink to a soft touchdown.  Don't try to force your wheels to touch as soon as you pull out and don't flare too high up because your sink rate will increase rapidly as you go below the stall so when you finally hit the runway it is too fast and the u/c breaks.    In an ideal world your wheels will be touching the runway just at stall speed - if you bounce you touched while well above the stall and if you come down with a crash you touched down well below the stall.

 

Some aircraft lose speed so fast with the throttle closed that it is better to keep some power on until you are fully down and some it is OK to close the throttle completely before you flare.  Try having just enough throttle to maintain the approach speed on finals and leaving it at that setting as you flare because (using a Spit as an example) if that setting allowed you to maintain 130mph while nose down on finals then once you level out and flare it will probably only allow you to maintain 70-80 MPH which is ideal for allowing you to sink gently. It also helps some aircraft to stay straight after touchdown.  If your aircraft needs no throttle at all to maintain the proper approach speed then it will be fine when flaring too.     Another hint:  Don't try to force at landing exactly at the threshold when still learning.  Use the whole runway when available and work towards landing on the numbers later. 

 

(Note:none of this applies to carrier landings where they have strengthened u/c so they can hit the deck hard with a large sink rate to avoid missing the cables.)

[ladlon]

Yep, all understood.  Just always seemed more like some reaction to the gear being down (again, as if it were causing some unbalanced turbulence or something).  Could be a number of things, as you guys pointed out.  I certainly haven't been watching the gauges in my landings so far... and, ya, I'm still weening off my 'modern General Aviation' muscle memory!  I've done a few good landings already... along with some lovely 180 slide ins, and no-holds-barred nose dip cartwheels.  Half the time, it's just me being impatient as I (too quickly) try and burn off some major altitude!

 

The sudden 'left roll' happened to me on takeoff last night, too.  I was in the He111 (...I FINALLY fully nailed the Norden site...  I didn't know about the autopilot until I read the Chuck's Manual... and that finally solved the odd 'intermittant tracking on/off' 'breathing' kind of thing I was seeing with the ground tracking.  Now, I just have to figure out why the sim refuses to allow any of my planes to have bombs!).

 

All good... Just kind of curious about the physics being simulated there.

 

Thanks for the link to the flight manuals, ATAG_KiwiFlieger.  I actually found those a week or so ago, and made a shortcut to them on my desktop.  Chuck's CloD manuals are also REALLY good.

Edited March 1, 2019 by ladlon

[Buzzsaw]

Yes, impatience during landing is a recipe for disaster.  ?

 

Re. Bombloads... you have to select the bombs and types for each bay.

 

Then you have to select the fuze type.

 

Then, after takeoff, you need to arm the bombs.

 

Please note, for most bombers, you cannot select maximum weight bombload and full fuel... the aircraft will not take off.

 

This is historical... Most aircraft used reduced fuel loads when flying with maximum bombload... and had reduced range.

[ladlon]

Amen to that...   Funny, when I NEED altitude, I'm low, and struggling to get any height...  When I need to get to the ground, I'm practically in space orbit!

[56RAF_Roblex]

3 hours ago, ladlon said:

Amen to that...   Funny, when I NEED altitude, I'm low, and struggling to get any height...  When I need to get to the ground, I'm practically in space orbit!

 

Same with airspeed.   I spend the whole sortie trying to coax the bitch to go faster than 250kph then when I RTB suddenly it's doing 600kph and refusing to slow down ?

 

[ladlon]

Ha!  Been there, done that!  I can't figure out how I can have such stupid fast speed, yet seem to stall fairly often during landing approaches.

 

But, again, I'm not paying attention to gauges or protocol so far...  Still tweeking the sim, getting things set up, as well as learn the systems, and figuring out the various things that I couldn't figure out up to now.  I finally got the Norden site conquered, as well as the gunner position systems (...kind of confusing when the manuals refer to a 'unbuckle straps' kind of command that I could never find.  There was always SOMETHING buggering up, so I never got to enjoy sitting in a gunner position while the AI piloted... until now.  Finally got that sorted out, including being able to control the gun aim with a mouse (since I can't use my flight stick for that).  Yep, once I can actually put bombs on my plane, I'll be all set to go!

 

Had  a fun session last night... Me with AI in 109s against a bunch of Spitfires... I shot down 2(?) during the main battle, then wounded one, and chased its smoking trail, trying to get it before it landed.  I managed to strike a fatal blow when he was literally about 10 feet from the runway, and he bellyflopped on the grass in front of it.  I took out another parked Spit right after that, so I think my tally was 4.  Having had to go to bed at that point, I just swung my 109 around and (tried to) land at the enemy airfield.... but, I was in too much of a hurry to get to bed, so I came in at something short of Mach 1.  I touched down, but had WAY too much energy, and just barreled across the field, knowing full well if I even tapped the brakes, I'd cartwheel...  But, as the bordering tree were rapidly approaching, I had to do something, so I tried pointing the nose up/down and tapping the brakes.  Needless to say, I ended up doing a lovely 180 ground spin, sheering off a wing and I think the front of the plane.  No fire or explosions, so I guess I walked away from that one.   (Assuming the enemy didn't then tap me on the shoulder and escourt me to their commander!)

Edited March 1, 2019 by ladlon