Hello-

I put a Supre Tigre 46 on my Avistar ARF, but it is extremely nose heavy. Do I add weight to the tail of the plane, or do I install a smaller engine? If I need to add weight, where on the tail do I place the weight?

Hi,

You can usually achieve the CofG by moving the batteries. If this isn't sufficient is it possible to move the motor to the rear on its' mounts? Adding weight is the last resort. BTW are you checking the CofG with the tank empty?

If you have to add weight add it as far to the rear as possible as a "little goes a long way" given you have most of the fuse to act as a lever. A few lead shot in epoxy or a cut down stick on wheel balance weight are simple solutions if this is required. A more "elegant" solution is to cut a small hatch at the rear to hide the weight. Just make certain the weight is well secured.

Cheers,

Colin

Yes, like Colin said, try shifting the battery or/and receiver to the rear of the fuselage to balance it on the CG. If those fail to make it happen, find out how much needs to be added and cut a small hole in the bottom of the rear sheeting, about the size of a BB pellet and mix some epoxy and bb's in a small cup to the same weight as the amont required. The easiest way to figure that out is to add the BB's to a plastic mixing cup about 1 oz in sixe and place it on the back of the fuse near the tail. When you've reached the proper amount of BB"s, just mix up enough epoxy to get them coated in the cup and insert them through the small hole with the tail pointing down, let them cure in the fuselage and recheck the balance, usually it will require a small adjustment but it will be close. BTW, if you need 4 ounces in the nose to balance the plane, your 1 ounce too heavy in the tail, the reverse of the formula works as well, so 1/4 ounce in the tail means 1 ounce in the nose too much. It almost always is a 4 to 1 ratio.

I have had/have two Avistars and both needed weight shifted rearward in order to get the CG at the suggested location. And by the way, it flies best with the CG right where it is recommended. In my current Avistar, I moved the battery as far back as I could, (two bays behind the former at the trailing edge of the wing, and I still had to add weight at the tail. The Super Tigre 46 is a fine engine, I'd stick with it and just make weight adjustments. Another idea is a friend of mine would move the engine and firewall rearward so that he didn't have to add weight. But that can be a lot of work. Anytime you have to add weight to get the CG right, always add it at the farthest extremity so that you can add the least amount.

I must add this though, I've checked the balance of my friends avistar and it seemed right in the middle of the range, well, one day while flying it, one of the main gear legs fell off while flying it, I landed it and had him snap it back in the slot. A few flights later the nose wheel fell off while in flight, I managed to land it and condenmed the plane till he fixed it, so losing the main gear on one side and wheel didn't make it uncontrolable, nor did losing the nose wheel. So the CG is very forgiving for a seasoned pilot, but for a beginner, it can wreak havok on your day. I suggest balancing it in the mid range of the instructions and make sure everything is solid before takeoff. I feel stupid for not checking his landing gear, but it happened not once, but twice in one day. My bad his gain for having me there to take over the stickas and bring it home.