Have a 3D plane HOW!!

[hifly2104]

Ok so I have an OMP Edge 540 80" profile.Powered by an mds2.18 turning a 20x6 apc prop at if I remember over 8500rpm.Plane is balanced right on the nose to the specs for the suggested CG.Most videos I see of 3d planes they fly slow with the tail feathers hanging down.Mine flies reasonably level and like a none 3d plane .So the CG specs are recommended starting point how much rearward can I safely go.Even with the brick off a motor up front I still needed to add weight up front.I have 2 4" bars of auto body solder,one on each side of the fuse so I could remove one.Engine side or other side??Would this help.Many people have told me if you get to tail heavy plane is uncontrollable.Any suggestions appreciated by a new too 3D flier

[NorseHammer]

Don't mess with the balance untill you have a lot of stick time with it. The 3D planes are just as much in need of good balance as any other. Practicaly the only flight regime that "seems" to benefit from a rearward CG is the hover, and even that is often debated. Check out with other flyers in your area who fly 3D or aerobatic styles, I don't think too many have a rearward CG on their planes, nuetral on the money balance seems to work best for most of us. Watching "High Alpha" flight manueveres with the wings partially or even fully stalled will give the spectator the idea that the plane may have a rearward CG, but this is rarely the case.

[SJrcflyer]

CG plays a fairly large role when it comes to hovering and like mentioned above high alpha stuff. But a balanced 3D should still fly straight and level upright and inverted. Profiles do tend to drag the tail if the cg is rearward but I find that its only those, full fuse planes I have noticed do not. (Maybe just me dreaming).

I prefer a slightly tail heavy plane but to be honest its just a matter of getting used to it. I would say stick with the book and slowly take some weight out of the nose untill you get where your comfortable wtih it and it seems to harrier nicely, and lock into a hover. You may find however that this makes the rest of your flight uncomfortable so its just going to be a fine line between the two.

[NorthernBoy]

I balance my profiles to fly level inverted with no elevator input. Then after that I get a feel how the planes flies as the tank empties. I find my Mojo will hover better with the tank at 25% full, so I am going to move my CG back. I recommend doing it slow. I also found a nose heavy profile would fly like a dog, IMO CG is important for a profiles performance.

[SJrcflyer]

I balance my profiles to fly level inverted with no elevator input. Then after that I get a feel how the planes flies as the tank empties. I find my Mojo will hover better with the tank at 25% full, so I am going to move my CG back. I recommend doing it slow. I also found a nose heavy profile would fly like a dog, IMO CG is important for a profiles performance.

I agree, except my Kat40 flew pretty d@mn good nose heavy, lol.

[hifly2104]

So the further back the CG is actually more nose heavy right. My specssay 1" to 1.5" back of wing tube so 1.5" would be nose heavier than 1" being tail heavy???

[SJrcflyer]

So the further back the CG is actually more nose heavy right. My specssay 1" to 1.5" back of wing tube so 1.5" would be nose heavier than 1" being tail heavy???

No other way around, if its 1" it will be nose heavy, if its at 1.5" it will be tail heavy. I would set it at 1.5" and you may find once your used to it you will have to go as far as 2" back. BUT TAKE YOUR TIME GETTING THERE!!!! It will just "feel right" when you hit the spot.

[OverTemp]

Just in case someone is missing the obvious here... I don't think you have a CG problem at all.

The planes don't just fly around with the tail hanging low... look at the elevator of someone doing it. It has a ton of deflection while flying the "Harrier".

A plane will fly a harrier whether nose-heavy or tailheavy... the CG usually just determines how stable it will be (as in wing rock).

To do a harrier, cut the throttle to idle and let the plane slow down... you want it pretty slow when learning, but not near stall, then apply full elevator and add some power back... you need to get the wings past stall fast or a wing rock may develop... now it is just juggling throttle and power to keep the nose where you want it. Steering is more difficult... it is a compromise between SOME bank and rudder... I often find in right turn I will actually be using left rudder to keep it from falling off the wing, and vice versa. A sim is good for learning this.

Please note... if you pull the throttle to idle the plane will not stay in a nose-high attitude... it will go flat and sink (called an elevator). The only thing that keeps the nose up is prop-wash over the elevator... adding throttle can make you pitch up OR climb, depending on the amount of power and elevator... like I said... it's a balancing act.

So, in summary.... a 3D plane flies just like any other plane when flying around... the only differences are big wings, high power, and large controls... it takes skill and practice to let the "tail feathers hang low".

Cheers

[OverTemp]

Oh... one more thing... DO NOT keep pushing the CG back trying to get the tail to drop... you will eventually reach a point called "longitudinal instability" where you will no longer be able to control the plane. Even if you're just a little tailheavy the plane can be a handful... having to use up elevator when inverted is a disconcerting feeling. You are obviously new and need to learn how she flies for a while.

The best way to adjust you CG for now... fly straight an level into wind and pull inot a 45 degrees climb. Roll inverted and the plane should continue on the 45 degree line or maybe even start to pull toward the canopy a little. If the nose pulls rapidly toward the canopy, move your CG aft. If the nose pitches toward the belly, move the CG back forward. When you reach the point where it hold the line then your CG is aft enough... then it's all stick, rudder, and THROTTLE management my man. Welcome to 3D!

[hillmanr2]

Do not get sucked into thinking you need a tail heavy plane for 3d. Balance the plane for IMAC type flying and increase deflection. I thought for a long time I needed to be tail heavy for 3d and found out I was wrong. Balance the plane for normal flight. Tail heavy sucks

My foamy that I use exclusivly for 3d is actually a hair nose heavy.
Go with 45 degrees or more of deflection on the tail and then change your exponential to work for you. You want as little expo as you can get on 3d rates. Just make sure you have enough to still maintain control in forward flight.

[hifly2104]

Thanks for all the hints guys.New no hardly been flying about 20 someodd years and hit 6tenths of a century this year.New to 3d yes former interest where 30 ish style planes still have a passion for the Gee Bee R2.Belong to a very small club 6 to 8 members,Field isn't purfect but we get by.After reading my first thread over this morning I decided to recheck my CG.I had done as they suggested when building keep an eye out for balance point as you build which I did so I was quite surprised when I had to add so much weight especially with the engine I had.This time I used a large carpenters square and guess what I was way to far forward .Removed the 2 chunks of lead and voila right on.Feel awful stupid after saying that it was right on .Well guess it was right on at the point I measured it at.Sometimes I guess we are all prone to overlooking the obvious Like the old joke I measured it twice and its still to short

[Ryan Davison]

Just so you know I can fly anything.
Not always a good thing.
Ok so I skimmed over some 3d balancing papers from my funtana mini (has an adjustable wing for cg :idea: ) last winter and said hey buy the looks of things. This making the funana fly better why not try bumping the cg back in my 60 size edge :idea: .
I went turbo stupid and put 2 hockey pucks in the tail of my 60 size edge and had the cg somewhere around the center of the cord. (20cm) the reccomended cg was 8cm which i found out recently.
Thought this would make hovering easier and 3d awesome. :rock:
I diddnt know much about cg at the time. :wstupid:

well I fired up on the lake (frozen) with skis and so on and Began My take off.Jan Blom was with me witnessing.
Well It was awesome in verticall allrite i diddnt even have to add up elevator from the takeoff to get it off the runway or into a hover. :shock: :yikes:
So I thought all was sweet as i was climbing verticall (thank god i had a 91 in it for power) then i wanted to go to level flight. It was at this point of the flight somthing clicked in my mind as i leveled out and the plane started to become very unstable and pitch wild.

The nose violently bobbed up and down on its own like crazy as i tried to keep it level and when the nose went down and i tried to pull it up the wings tip stalled and it dropped a few feet in a spiral.
I climbed up after that and thought HOLY :censored: :taped: :yikes: :help: What am i gonna do and there is no way im going to land this plane in less than 500 million peices.
Told Jan that the plane was going nuts and that there was no way in heck i was going to land it.
I diddnt even bother asking if he wanted to do the honours.
Well Shaking like crazy i kept the plane going very fast and lost some altutude trying to make a final aproach
it took 3 trys till i got the plane low enough to make a go for it.
got the plane somehow to keep the speed and stay somewhat level a few feet above the ice.
I killed the motor as i figured this was as close as i was gonna get and the plane just started to go into a tip stall as the skiis met the ice.
The plane landed in one peice somehow and i was really amazed.
was either a maricle or shoot luck
so yeah I took the pucks out and started again by add in 2 pennies for the next flight.MUCH MUCH better.got it balanced really good now.Jan managed to torq roll it for me (demo)So it must be alright.

Now I just have to get my but in gear trying to do all the cool 3d tricks with it.
Getting there.But yeah defenitly have to be carefull of how much weight you add to the tail.

PS
Oh reading the manual helps too
Just my 2 cents and a funny story

[OverTemp]

You experienced longitudinal instability.

The CG of any airplane MUST be in front of the aerodynamic center in order to be stable. Hence the saying... "A nose heavy plane flies poorly, a tailheavy plane flies once!!!"

There was a commuter plane taking off in NC a while ago. When they loaded the bags they didn't weigh them or check CG at all, and it was loaded too far aft. After take-off the plane rolled over on its back and plowed into a hanger killing everyone. You just can't overcome physics... even if your own life is in your hands.

You got real lucky!

[Ryan Davison]

Wow Guess I did.

Kool saying haha (once)

breaking rules of physics with my edge 540 lol

It was quite a test of skill too bringing it down.

Glad i have it still

flies excellent now that its properly balanced

[juice90]

well. that was an interesting fourm. I have often wondered about how the harrier works as far as balanceing was concerened.

I all ready knew about the effects of a tail heavy airplane, and couldn't understand how it could be tail heavy and seemingly stable.... but it now makes sense...

Big wing, lots of power and lots of elevator throw :yikes:

[hillmanr2]

well. that was an interesting fourm. I have often wondered about how the harrier works as far as balanceing was concerened.

I all ready knew about the effects of a tail heavy airplane, and couldn't understand how it could be tail heavy and seemingly stable.... but it now makes sense...

Big wing, lots of power and lots of elevator throw :yikes:

Not so much big wing. A harrier is using both prop and wing. Lots of throw but it has to do more with a balance of throttle than anything else. 3d post/ stall maneuvers require the pilot to be able to use the rudder/throttle equally as well as the elev/ailerons. All four controls must be inputted simultaneously.

[juice90]

I am not an expert at 3 d... just startin to try it actually... nose heavy plane is a pig to fly and tail heavy loves to snap. so u want to find an inbetween.

I was pokeing around on the flying cirkus site and found a video for balanceing ur plane, and I tried it this past week and it seemed to work.

roll ur plane inverted and climb at 45 degrees and release the sticks and watch what happens.. U want the plane to slowly nose over in the climb. too quick, and its nose heavy, if it requires up elevator ( ur inverted remember ) or stays climbing ur bordering on tail heavy. And this is assumeing all else is set up right.
The plane I tried this with dropped nose fairly quick, so I added 1/4 oz of lead to the tail and it made quite a difference. Unfortunatly, the muffler came appart and I haven't been back out to see what it did to other charactoristics yet.

Go to the flyin cirkus site and look at the trimming vids. They will help alot