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Ground effect.


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I was thinking about landings in LO & how generally it seems accepted that LO has pretty good SFM & very good AFM, but that landing is not the strong point of either – particularly the SFM.

 

Given that ground effect only occurs close to the ground (Within ½ a wingspan of the ground ?) & that LO already continually calculates how far the planes are from the ground already – not least importantly for ground collision calculations – it seems to me that it wouldn’t be that great a step to modify the lift calculations so that as the aircraft passed within ½ a wingspan of the ground the lift generated was scaled up linearly to replicate this effect (if the height calculation was taken from the middle of the wings, the plane could still actually touch the ground, even with a linear calculation). Probably you would disable the effect at more than say ~ 20 degrees bank.

 

I see three advantages to adding ground effect – not in any particular order they are:

 

1/ More realistic landings, both for AFM & SFM models. Perhaps even more noticeable for the SFM (which may have disappeared by the time E.D. could implement something) where at present you can just fly in at any old speed, bang her down & put the brakes on, but this would also add to the landings of the AFM planes (especially with randomly fluctuating wind gusts).

 

2/ Less hitting the ground when flying NOE – both in transit & during attack runs ground pounding. Real life aircraft to some extent create their own air cushion underneath themselves, which reduces the chances of their just dropping onto the ground at 1m/sec with a steady stick while flying over level ground. A bit of ground effect might also just make the difference between bottoming out with some part of the plane 5cm below ground and bottoming out 10cm above ground when trying to pull up after a ground attack run.

 

3/ I’m not so sure about this, but ground effect might help cover up some of the errors in the terrain mesh. At present there are quite a lot of places among the sides/tops of hills/mountains where the collision detection part of the terrain modeling doesn’t quite line up with the visual representation of the ground. The first thing the pilot knows about this is when their plane hits the mid air ridge. I’m not sure, but I guess that the ‘collision’ mesh is still actually contoured in these cases, in which case ground effect might help by giving the plane a little nudge away from the invisible ground - & in doing so also give the pilot a clue that they’re over dodgy ground & need to give it a bit more clearance.

 

(I know this has been discussed before, but I think it's not a bad time for a reminder to E.D.)

Cheers.

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As long as we all agree that it's not "an invisible cushion of air"!:pilotfly: :megalol:

 

LD

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As long as we all agree that it's not "an invisible cushion of air"!:pilotfly: :megalol:

 

LD

 

Whats wrong with that definition?...do you know how the effect is produced?

oo err...missus:animals_bunny:

 

** Anti-Pastie**

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ok..hold tight and bear with me..this is what i know on ground effect.

 

Ground Effect:

If u were very slow and cautious in raising the collective,u may find that the helicopter slowly rises a short distance and to the hover a few feet off the ground without any change in the collective setting.

 

If this happens,u can congratulate yourself on having demonstrated ground effect,riding on an air cusion produced by the rotor downwash.

 

Ground effect magnifies the lifting power availiable for a given collective setting,but the effect falls off quite rapidly with height,and dissapears altogether at a height equal to the diameter of the rotor disc.

 

Rough or sloping ground,violent manoevering or strong,gusty winds will all tend to spill the air cusion,push it off to one side,or prevent it forming in the first place,so a wise pilot is cautious about depending on ground effect for the lift needed to stay airbourne.

 

In any case,for our first transition to forward flight we want to climb rather higher than this-say to a minimum of 100 ft/30mtrs.

 

As u approach the desired height,ease the collective down slightly and weight to see the effect.

 

Remember that a helicopter has momentum-the faster u were climbing (or descending),the longer it will take for your verticle speed to change till it actually reflects the new collective setting.

 

As u lower the the collective,u'll also need to coordinate with pedal input.

 

With practice,u can anticipate the effects of ur control input's..but be carefull in the early stages-it's hard to avoid over-correcting.

 

Phew! sry bout the long post but i hope this helps some peeps to understand Ground effect in helicopters.

 

p.s theres more to it..but i hope the kinda explaines Ground Effect.

 

Weta (or mods) why not post this in the The Ka-50 Black Shark thread to keep all info in one place ;)

Be Good..Be Strong..:drink: ;)

 

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cheer's..as i said above theres more to it..;) hopefully this gives some people an idea on what Ground Effect is..rdy for BS :)

 

Translational lift btw is another subject ;) like these:

 

Taking off and rising to the hover

 

Ground effect (allready mentioned)

 

Transition from the hover to forward flight

 

Translational lift (allready mentioned) Climbing and diving

 

Turning in forward flight

 

Slowing to the hover from forward flight

 

Landing problems and techniques

 

Visibility factors

 

Circuit pattern

 

Final approach..the list goes on ;)

Be Good..Be Strong..:drink: ;)

 

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Hi, Partly I didn't post in the Ka-50 section 'cause 1/ I don't think there'll be time to implement this in LOBS (even though I suspect that as far as FM changes go this might be an easy one) & 2/ ground effect would be just a good effect to have in the fixed wing aircraft too (Maybe an AI Caspian sea monster :-) (JK)

Maybe we need to get a wish list sticky again.

Cheers.

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Sleek, stop trying to pass on other peoples work as your own, its called plagerism. Firstly you can tell its not your work, because it is not how you normally post, the stolen text sticks out from the start and end of your posts. It is clear you changed a few words and grammer to make it look like yours.

 

You stole it from the enemy engaged ground school documents. Look under ground effects here:

 

http://www.razorworks.com/enemyengaged/usmanual/Chapter6.PDF Page 9.

 

Nice try :) but in future, please reference where you copy your text from.

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listen... not once did i say it was my own work!,i said its what i know!!(after reading the EEAH manual yes) or do i wan't any praise so just chill out..and again like i said i hope it help's some people out.

 

BTW if i knew there was a pdf doc do ya really think i would of sat here and typed all of that from the EEAH originall Manuall when i could of just posted a link like u did.

Be Good..Be Strong..:drink: ;)

 

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