Problem with CG Location
 

Could you please help me with a couple of balance issues.
World Models, Super Sport 40, TT 42GP engine.

Problem, Center of Gravity is 35mm Aft of manufacturers recomendations. all up with an empty fuel tank.

Questions, Do you check CG with an empty tank ?.
To balance as per instructions I will need to load 5<6oz of lead into the front of the plane , IS THIS NORMAL?
How accurate does the CG need to be?

Thanks in advance for the help.

RE: Problem with CG Location
 

in ARF models dont have to worry so much about it. ESp WM this make quality planes.. and yea u measure with an empty fuel tank

RE: Problem with CG Location
 

I am not entirely familiar with the internal layout of your plane, but if you can, you might try moving stuff around (primarily the receiver and battery) before adding weight. Also, you might look into finding a heavy hub (a prop nut that is heavy and adds some wieght while being useful) to help shift the weight forward. There is a saying that I have heard that has been proven true everytime I see a plane that hasn't been balanced before its maiden: nose heavy planes fly poorly, tail heavy planes fly once.

Do what you can and make sure you get your instructor or someone at the local hobby shop check out your plane before the first flight. The may pick up on something that you never thought of or had reversed. When I first got into the hobby, it took about 3-4 trips to the field before my plane was completely ready to fly.

Good luck!

RE: Problem with CG Location
 

1. Yes check with empty fual tank

2. Yes unfortunately many AFf's tend to come out tail heavy. Minimise the lead and move stuff forward, get the battery up front under or over the fual tank and move everything forward if possible. By the way the quality of the airplane makes no differance at all, a tail heavy airplane is a killer.

3. Needs to be accurate. Poorly balanced models (particularly when tailheavy) along with excessive control throws are simply the number one killers of new airplanes. additionally when you balence an airplane and cheat a little nose down for 'mother and courtry' you have now balanced the airplane at an unknown position. The airplane is only balanced at the desired position when it is level!


John

RE: Problem with CG Location
 

I had same plane as you and it balanced a little nose heavy with battery and receiver mounted in supplied foam block at the front of the radio compartment, just behind teh fuel tank. Battery in front of the receiver...
I had a Supertigre GS 40 engine up front and it needed no nose weight. IF you have to, slide the receiver battery under the fuel tank, but try not to add weight if you can avoid it. That's a great flying airplane, mine was nose heavy but not much, but considering it was my first low wing plane that's how I wanted it.


Andy

RE: Problem with CG Location
 

Listen to a65l, there is no way that you would need to put weight on the nose of that plane. Put the batteries and reciever up front and you should be fine. Plus 5-6oz is way way too much for a plane that size!

Try with the battery beneath the fuel tank first (remember, up is down when your plane is upside down!)

RE: Problem with CG Location
 

Do not fly the plane in a tail heavy condition. Forget the advice not to worry about it, while others' may not have come out tail heavy, it seems your's has.

If you used a lighter engine than someone else, then your's may well be tail heavy and may not survive the first flight unless you balance it. Move the battery pack & receiver forward, you may even be able to move the engine forward on the mount.
Dennis-

RE: Problem with CG Location
 

Something I'd like to add is that if you do need lead in the nose, don't be afraid to add it. Some people act like adding lead is the end of the world - it's not.

I have had to add as much as 15 ounces of lead to a plane - and it flew like it weighed nothing.


So while adding weight is the last thing you should do, it's by no means a sin.

RE: Problem with CG Location
 

Had same plane and engine combo. It also balanced tail heavy just add weight and fly. Mine flew great.

RE: Problem with CG Location
 

I've had to replace engine mounts a couple of times because I wasn't thinking and mounted the engine back on the mouts. Even a 1/8-1/4" moving the engine forward on the mout can have a big effect on the weight you need to add.

I also just did a neat trick on a waco bipe that was coming out tail heavy. The firewall is big and round, and the cowl had lots of empty space in it. So I bolted a second engine mount to the firewall, and mounted the lead to the end of the engine mount. That got it a good 2" in front of the firewall, and I needed less than half the lead in that more forward location. Obviously, I made darn sure the lead won't vibrate loose, if it does, it's the end of the plane.

RE: Problem with CG Location
 

Thanks gent's, I will move the batt pack forward and see if it needs any more, I have 1/4 inch on the engine mount that can use so I just might be OK, I maybe should have used a top end for the extra wieght. I hope to fly next week, bit nervous, first low wing and all that, thank you all for your help.

RE: Problem with CG Location
 

You're gonna be amazed how nicely that plane flies and lands. I rejoined the hobby about a year ago and soloed on an Avistar. The day the Avistar succcumed to a midair, I bought the SS 40. Next weekend I was out at the field, but nobody there I knew to maiden it for me. There wre a couple guys there, I didn't know them very well but they both seemed to be fairly competent pilots. I taxied around for a bit to get the feel of the plane and make sure nothing was going to vibrate off. Then the older fellow, he makes the comment that "it sure looks nice on the ground". Well, it's calm, I'm feeling good, so I took it out on the runway and off I went. It was a little hairy at first, but very quickly I got it trimmed and was really suprised how well it landed. Easier than the Avistar, IMHO. My first low winger and my first maiden flight. Then I went and stuck my finger in the prop and thus ended the flying day.....


Andy

RE: Problem with CG Location
 

Minnflyer's hit it on the nose... it's far more important to get the CG right.