I just built the superstar 40 with the dihedhrial taken out and decided to go with the .46 AX motor. In order to get the CG anywhere near spec. 3 3/8 inches from leading edge is by putting nearly 6-7 ounces of ballast to the rear of the plane. There is gotta be a easier way.
Ive read many posts with people using the 46 fx in it, with no trouble (im thinking). Since they stopped with the FX line and going to the AX series which is a heavier motor. Inside the fuse there isn't much room for movement of the Battery and Reciever. And I allready have the motor moved as far back as it can go. I kinda dont want to rip the covering off the rear of the plane to add that much weight. Would the composite variety of Motor mount work better, if so what brand is recommended?

Something is wrong. I'd check the website and see if there is a correction on the CG. 3 3/8 seems short, but may be correct. Rarely is a kit that tail heavy. I assume you are balancing with an empty tank. Balance should be between 3 1/4 to 3 5/8. Wish I could be more help.

rcfury, there is something definately wrong with this picture. I haven't flown my trainer in over a year, but the CG is 3-5/8" (92mm) from the leading edge. Make the CG be 25-30% of the wing chord. I had a 46FX up front also. I had to put only 1 ounce of weight on the tail to balance. Are you checking the CG with a full tank or empty? It should be empty.

The OS 46FX's weight: 16.45 oz w/muffler
The OS 46AX's weight: 17.2 oz w/muffler

The weight of the engine has nothing to do with you having to put 6-7 oz on the tail. Make sure your CG is correct and the tank is completely empty. Was this an ARF? Has it been nosed in before? If so, epoxy does add up if too much has been used in excess.

DTB

Well, I know the tank is completely empty becuase i havn't flown it yet. Im at the stage to double check the CG before the first flight. Yeah i did notice that I typed in the wrong CG on the orginal post. I personally am really confused because I triple checked the mesurement on the greatplanes CG machine. I guess its from the excess expoy but, that much? I konw i did use a good amount on the wing halfs to make sure they are strong. But that is right above the CG so it shouldn't be much of a differance.

There's still something wrong there. How are you placing the plane on the CG machine? If it's a high wing plane, right side up, correct? Your measuring right where the wing meets the fuselage, not out on the wing somewhere, yes?

6 or 7 ounces in the tail means the nose has an extra 20 to 25 ounces! That's about a pound and a half, and I don't believe that's possible.
Dennis-

Everything worked fine on my combat plane, and Ive decided to go with a wighwing trainer and do some maybe AP. I measure the CG right next to the fuse just llike on my other plane. Im placing the plane right side up since it is a highwing. The two pins sticking up are touching the leading edge and i take the measurement with the sliding rule.

Im going to take the motor out anyway and tear it apart. I have this pet peave of mine that i have to take new motors apart and give them a good cleaning. I had one ROSSI crap out on me due to some burring from factory. I just placed the motor on the plane for the time being to check the CG and found its so front heavy.. ill take a pic of it, Very weird!

I think the source of confusion here is there is actually 3 different flavors of the superstar, each with individual specs. There's the RTF version, ARF version, and the AWARF (all-wood) version.

Tower hobbies web site has the right CG figures and control surface throws for each flavor of Superstar, last time I checked. Or you could check out the Great Planes/Hobbico site.

HTH,

-Matt

i have the superstar with the monokote. I checked the hobbico website for the specs. and it was the same with the intructions that came with the kit.
I started playing around with the layout inside the fuse. If i moved the battery and reciever on top of the servos i maybe enlimated maybe 2 oz of weight.
Still i kinda dont want to do that because i will then loose the accessabity of the servos. I dont want to move the battery in the rear of the plane, but i may have to. Speaking of, what is the best way of making a hatch on the rear of the fuse? If i have to resort to moving the battery.

I managed to stick two bits of velcro down towards the rear of my plane by using tweezers through the servo area. This worked fine but I stupidly only used rubberbands to attach the batter to the anti-vibration foam that was then stuck to the velcro strips. The battery slipped out, luckily it happened on after a landing. I have now used a tie-wrap to attach the battery to the foam. In the end though I just cut a big ugly hole in the side of my plane. If I ever need to get at the battery I will have to cut another hole in the side of my plane.

Without having the battery as far back as possible I just found the plane to be way too nose heavy. It is still nose heavy with the battery near the back, but the situation seems to be manageable.

It is easier to show you than to explain. The latest hatch I made has 1/16" x 1/4" for support on the inside hatch with a piece of balsa at the bottom to secure it to the plane. The opening of the hatch has some harder wood like basswood or any harder wood CA'd to the inside of the hatch so you can put a screw into it to hold the hatch cover.

Below are some photos of the hatches I made for my Fat Free Taco and not my Superstar 40, but the concept is the same. Just make yours smaller to allow the placement of the battery.

**Note** Camera quality is very low. $20 Digital Camera from Wal-Mart until I get a better one.

rcfury,

If you do move the battery back, a good rule of thumb is to make sure that the receiver is further back than the battery.

That way if your battery gets loose (like during hard beginner landings) you don't end up crushing/breaking your receiver.

There is nothing wrong with putting lots of weight towards the tail of the plane, as long as it is secure and everything balances correctly.

Have fun!

-Matt

If you don't mind having a plane that is much heavier then originally designed i.e. higher wing loading.

I would try to shift the servos and or rx and battery around. Also look at a light weight spinner nut and light wheit wheels especially for the nose gear.

Don't take this the wrong way I have the CG machine also and the rulers are metric on one side and standard on the other any chance you are using the wrong side for measurement??

RCfury, there is nothing wrong with adding weight if you have to, but I prefer to move around things to achieve the proper CG first, plus this keeps the weight down. For a trainer, adding weight is no big deal, but for a profile or any fun-fly type of plane, you would much prefer to move things around instead of adding weight. Learning and doing this from the beginning is good to do because you will train yourself to do this first when you move onto more advanced planes. A little nose heavy is good on a trainer. This will make the trainer less responsive and more docile, thus making it easier to control in the air

Rule of thumb: Move objects around first before adding additional dead weight. Adding weight should be a last resort. Less things to fall off and through the CG off while you are flying.

My thoughts on the matter.

rcfury,

I had the same issue with my SuperStar with a Magnum xl .46.

I did the following, and the plane flew great:
Mounted the battery pack behind the servos. That made a big difference, and didn't take a lot of effort. There are a number of ways to do it. Just make sure it's wrapped in foam, fastened securely, and not blocking the movement of the pushrods.
Mounted the receiver back as close to the servos. That helped a little.
Mounted the engine as far back on the mounts as possible. You already did that.
Took off the spinner, which helped a little.

As others have written, you can add weight to the tail, but as your flying skills improve, you're not going to like the plane as much. Better to move things around and keep the plane as light as possible.

JMHO

Well, this is a beginner forum after all! I foolishly made the assumption the the OP would want the simpiest, get it in the air and not sweat the small stuff answer!

thank you for all the comments.
Im not quite the beginner, I know what im doing but i could always be better. Anyway...
I definatly agree with adding weight as the last resort. Thats why i want to move the battery back in the rear of the plane. I dont mind adding one ounce to the plane, I just hate to put up to 6-7 ounces!!!!
DTB: Thank you for the pictures, I would think it should be pretty easy to contruct...

Well, i made a small hatch in the rear of my plane.. I orginally used my flat RX battery in the spot, but it ended up being to heavy, so i found an extra 4 cell sqare pack which is much smaller and lighter. After everything bolted together, I put it back on the CG machine and it ended up being slightly nose heavy which im going to keep till i get used to the plane. Up front the servos and reciever is in its stock location.
Thanks for all the replys..

Great rcfury, now go have some fun with that bird....