RE: E-SKY LAMA 2 THREAD  
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RE: E-SKY LAMA 2 THREAD - 1/2/2006 4:06:56 AM   
Kamikazi


 

Posts: 194
Joined: 11/4/2003
From: Osceola Mills, PA, USA
Status: offline 		What we're calling a flybar is actually a stabilizer bar on these coaxial helis. There is a difference in that no control inputs are fed into the stabilizer bar, but the flybar of a conventional bell-hiller model heli is connected to the swashplate through a set of mixing arms and pushrods.

Well, anyway - that's not so important, but the cyclic pitch changes to the upper rotor by the stabilizer bar are important - it's not an effect you can duplicate by putting weights on the tips of the blades.

Full scale Helis don't normally use flybars because their control responses are adequately damped by the sheer mass of the machine - things happen slow enough that a human being can keep up. Although there are a few flybar-less model helicopters around, none that I know of are micro-helis. These tiny little machines have almost no inertia and are extremely twitchy without some other mechanism to dampen control inputs.

What you propose would be an interesting experiment, but I suspect that without some type of stabilization system, it would be virtually unflyable...

Greg

(in reply to thecheatscalc)
       Post #: 226

RE: E-SKY LAMA 2 THREAD - 1/2/2006 8:02:03 AM   
korb



Posts: 71
Joined: 8/22/2005
From: Hong KongHong Kong, HONG KONG
Status: offline 		yo

A few Questions on ground effect :
1) What is ground effect roughly ?
2)where does ground affect happen (how high do u have to be to not be affected)?
3) is there any difference in flying - between ground affect and when ure not affected?
4) does it affect the trims ?
5) does it affect flying in general ?

thx for any/all answers !!

kp

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(in reply to thecheatscalc)
       Post #: 227

RE: E-SKY LAMA 2 THREAD - 1/2/2006 8:38:33 AM   
nubli


 

Posts: 28
Joined: 11/29/2003
From: alor setar, MALAYSIA
Status: offline 		i tried to answer about ground effect;

1. it is gravitational effect when your model heli or plane are close to ground. some of our control input won't be effective, the gravity will pull down everything, we have to fight it. don't be too close to ground, it might spells "disaster"...

2. that's why 30 cm off the ground or 15" will be a safe start for our lama 2 as suggested by the manufacturer. beleive me i broke one blade and disfigured the other three... already lol....

any body got video footage on their lama 2...

tomorrow i'm going to shoot 10 minutes video and going to post it here.... got any server that i can park the vid?

i'm too happy with my lama 2. within one week i'm able to fly it.. my first experience with heli (actually i flew planes for 25 years already and no gut to try heli) thanks.

(in reply to korb)
       Post #: 228

RE: E-SKY LAMA 2 THREAD - 1/2/2006 11:20:18 AM   
Stormovic


 

Posts: 209
Joined: 1/18/2003
From: Morris, AL, USA
Status: offline 		Good explanation on the stabilizer bar or (flybar).

(in reply to nubli)
       Post #: 229

RE: E-SKY LAMA 2 THREAD - 1/2/2006 12:53:13 PM   
SimonHK


 

Posts: 6
Joined: 11/21/2005
From: london, UNITED KINGDOM
Status: offline 		Nubli, I sure hope that its the 'language barrier' that made your ground effect explanation so off-base!
Its nothing to do with gravity, its the ground interfering and interacting with the airflow from the rotor, effectively the ground 'pushes back', you get ever so slightly increased pressure under the helicopter. It more turbulent, so more difficult to control the heli. It also takes slightly less power to hover in GE than out of it.

Look up "ground effect vehicles".. and the infamous Russion Ekranoplanes.

SimonHK

(in reply to Stormovic)
       Post #: 230

RE: E-SKY LAMA 2 THREAD - 1/2/2006 1:39:48 PM   
Kamikazi


 

Posts: 194
Joined: 11/4/2003
From: Osceola Mills, PA, USA
Status: offline 		Ground effect - here's a good link:

http://www.copters.com/aero/ground_effect.html

On the Lama2 you can easily feel it when you land. You have to reduce power considerably to get it to actually touchdown. It's very noticeable when the heli is only a few inches above the floor.

A major part of the instability is certainly caused by turbulence from the rotorwash being deflected by the floor and nearby objects, but there is another cause of instability too. The Lama2 is fixed pitch (as opposed to collective pitch), so the rotor speed must be slowed greatly in order to reduce the lift enough to get it to touchdown. The rotors (and stabilizer bar) are less effective at slower speeds.

The rudder trim does indeed seem to change while in ground effect. Good question. I'd guess it's due to the fact that the ground effect cushion is spiraling slightly, but I suppose it's also possible the the rotor speed mixer doesn't work so well as slower rotor speeds.
I don't really notice this on my larger Helis - but I fly HH gyros on all of them...

(in reply to SimonHK)
       Post #: 231

RE: E-SKY LAMA 2 THREAD - 1/3/2006 10:21:38 PM   
guy5927



Posts: 84
Joined: 12/16/2003
From: Gistel, BELGIUM
Status: offline 		hmmm ....

The swasplate has to be tilted quite a bit in default trim position to maintain something of a hover ... I say something because it makes a slow horizontal circular motion ....

Bad 4-in-one ? something crooked ...? CG seems right ...

(in reply to Kamikazi)
       Post #: 232

RE: E-SKY LAMA 2 THREAD - 1/3/2006 11:34:59 PM   
MikeMc



Posts: 572
Joined: 2/19/2004
From: Union City, CA, USA
Status: offline 		For some ground effect fun try landing on a tiny TV dinner table. You'll see you keep getting pushed away from the table.

< Message edited by MikeMc -- 1/3/2006 11:35:21 PM >

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(in reply to guy5927)
       Post #: 233

RE: E-SKY LAMA 2 THREAD - 1/4/2006 12:21:56 AM   
thecheatscalc



Posts: 1228
Joined: 8/13/2005
From: fayetteville, GA, USA
Status: offline 		heh, I tried landing on a pan, (and someone's flat head ) and it was amazing how much forward I had to push before I could land properly, when which once I got over the effect I was already overshot.... if you want a landing pad with none of that, buy a grid of thin, yet deep mesh of rectangles, similar to a radiator coils, just a little more space imbetween.

Well, I've gotten over the problem of the flybar, for the moment, I used a glob of JB WELD to fix it, and it worked great, it held the fly... ok stabilizer bar under starting and stopping stresses very nicely, but, when I crashed (seeing how fast the bugar could go, not very) it just popped off and revealed that I had forgotten to remove the CA from the joint (I had tried to CA it back, didn't work) so, after a careful sanding job I've reglued it (setting a REGULAR lightbulb, on, next to the joint while it's drying works wonders, dries in about 2/5 the time. The secret to the stuff is it's a form of epoxy mixed with very fine metal shavings which are basicly absorbed by the epoxy. I have a few super magnets laying around, so, I had some fun watching the "blob" move around. anyways, it seems to have done a good job, I'm waiting for the skid glue to dry to see if it works there, but so far I'd recommend it, but, nothing makes it worth using than the advertisement on the back from somone "I've decided this is even better than bailing wire"

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(in reply to MikeMc)
       Post #: 234

RE: E-SKY LAMA 2 THREAD - 1/4/2006 12:09:06 PM   
Kamikazi


 

Posts: 194
Joined: 11/4/2003
From: Osceola Mills, PA, USA
Status: offline 		Spare LiPo packs -

They are out of stock for a couple of weeks, but these might be the best price you'll find on a LiPo for the Lama2. Their packs appear to come with the same type of balancing connector. You'd need to double check the wiring though... And you'll still have to supply the JST connector (about $1).

(in reply to thecheatscalc)
       Post #: 235

RE: E-SKY LAMA 2 THREAD - 1/4/2006 1:02:29 PM   
Norrmannen


 

Posts: 217
Joined: 3/26/2004
From: Akershus, NORWAY
Status: offline 		Check to se if C value is high enough.
I can fly abt 10 minutes with my Lama which means it needs abt 5 A continously. Battery gets warm.
These cheap cells can deliver 0.8x8C=6.4A. personally I find the margin a bit small.
I'd go for the 10C packs if they fit and get available.

(in reply to Kamikazi)
       Post #: 236

RE: E-SKY LAMA 2 THREAD - 1/4/2006 1:40:27 PM   
thecheatscalc



Posts: 1228
Joined: 8/13/2005
From: fayetteville, GA, USA
Status: offline 		ok, it's picture time, yesterday I allowed my dad to fly, he flew, crashed (lightly, but it's still a crash...) and the TOP FIX HELD! so, basicly, I'd suggest using JB weld to fix the top piece, and the greatest part is: it bonds to itself quite well.


in any case, I'm waiting for my dad's lama 2 to (too?) come in, and mine is charging, I tried messing with the little countering screw in the heli, which, did really nothing, how do you iron blades?


oops, pics later today, I've got to go for the moment.

_____________________________

www.ushobbysupply.com - your #4 HQ!
All stock located in the U-S of A!

(in reply to Norrmannen)
       Post #: 237

RE: E-SKY LAMA 2 THREAD - 1/4/2006 2:52:58 PM   
Kamikazi


 

Posts: 194
Joined: 11/4/2003
From: Osceola Mills, PA, USA
Status: offline 		This is certainly a concern - but I have to wonder if the stock Esky supplied Lipo is of better quality - if it's even as good. These commonsenserc Lipos seem to be getting high marks for quality and conservative ratings.
They are new on the market, so their long-term durability is unknown. But the quality of the ESky LiPo is also pretty much unknown. For this price they would seem to well worth trying - especially if someone is looking for a bargain.

(in reply to Norrmannen)
       Post #: 238

RE: E-SKY LAMA 2 THREAD - 1/4/2006 3:22:26 PM   
Norrmannen


 

Posts: 217
Joined: 3/26/2004
From: Akershus, NORWAY
Status: offline 		I've done som "bargains" on cheap LiPos in the past, turned out not so bargainlike afterall....

From experience I believe many will overrate their batteries, some considerably.

Judging from previous lipo experience I'd say the Esky lipo is more than these claimed 8Cs but thats just mho.
Judging by Eskys homepage they are 10C (my chinese is a bit rusty, putting it mildly..)

But I found this too:

http://www.hobby88.com/shop/product_info.php?cPath=46&products_id=221&osCsid=3920acb426f88b6f0f02a6d63d325b6e

And this:
http://www.valley.ne.jp/~mdi/rc/battery.htm

< Message edited by Norrmannen -- 1/4/2006 3:25:14 PM >

(in reply to Kamikazi)