hi guys, i'm wondering if you can help me out? my neighbor got an avistar arf and put it together by closely following the directions. i helped him do the finish assemble. things like pushrods, centering servos, set up throws, and other things. well it came time to put a motor in it. he didn't have one, so i loaned him one of mine. it's a o.s. .46 fxi , from my nexstar. so anyway, i put it on for him. and then went to balance it. well it's nose heavy, i put it on the balancer and the nose went right down when i tried to let go. i looked around the plane, things seemed to put ok. well my ? is, is the o.s. .46 fxi to heavy of a motor for this plane? i've heard other people put .46's in theirs. so to save my neighbor some money, i loaned him mine. but i don't know now. is there a different .46 that would work? that he could get. also, would switching the receiver and batt make that much of a difference balance wise. since they're right next to each other? thanks guys

The Avistar was designed around the OS LA 40 which has less displacement and therefore lighter than the .46 but it is also lighter by virtue of having bushings instead of bearings. The LA 40 is plenty of power for this plane so the .46 will be almost too much. You will have to add weight to the tail so that the plane balances correctly. Once properly balanced it should fly fine even with the .46 although it may land a bit faster because of the extra weight.

My buddy Bill had the same issue with his Avistar. His had the LA .40 on it when we got it. Then he installed his .46 AX to break that motor in and there was a huge diferance. He moved the battery back behind the servo tray and added weight to the tail to make it work.

I have a TT .46 on mine and it balances fine by placing the Rx battery behind rear bulkhead the servo tray.
It's a pain in the rear to get there, but it prevented me from adding any additional weight. But then I also made it a
tail-dragger and have the extra weight from the tail wheel in the rear to help...

after moving the batt, how are you guys adding weight to the tail? and how much did you have to ad? thanks

Move the battery back behind the servo tray and rebalance. If it still doesn't balance, move the battery back even more. You may have to secure the battery between two aft fuselage formers.

how do i get in there, cut the plane open?

I wouldn't cut the plane open to move the battery pack. If you can install some eye hooks and strap it to a former or something, that will work fine. I just had a buddy's Avistar for a few days, with my 46AX, and the plane flew great. We mounted the battery as far back as possible. There might have been some lead weights already installed under the stab on that plane, though. Also where did you find the CG location? Are you sure it's right? Should be 3.25in back from the leading edge of the wing. Also your fuel tank should be empty when you balance it.

I put a Super Tigre 45 in my Avistar and I needed to add about two ounces of weight to the tail to get it to balance. The ST 45 is a very heavy engine for it's size. But given that, my Avistar is still very fast and is a blast to fly. I've had it for over five years and I still get it out every so often because it's just a fun, fast, relaxing plane to fly. I must have close to four hundred flights on it by now. So I wouldn't worry about a couple of onces of weight in the tail. With the 46, the Avistar can easily handle it.

As for the weight, all I used was the lead strips that have double sided sticky tape on them. You can usually pick them up at your LHS. You just cut them to size and stick them on. For this plane, that's all you really need. But just check them occasionally for the residue from the engine can cause them to come lose.

Jim...

No, you can reach behind the servo tray into the fuselage. You shouldn't need it WAY back there. Just make sure you secure it with something.

I got a 46AX on mine. Here's what I did.

Behind the servo tray is a hold that goes into the fuse.... the bottom is flat. Spread some thin CA to hard the balsa a little and stick on some velcro. Put some velcro on the battery as well. Slide the battery back through the hole and stick it on to the velcro (as far back as possible in that section of the fuse).

If it's still too nose heavy *mine was*, I dipped some weight in epoxy and dropped it WAY back in the fuse... and voila... plane balanced with addition very minimal weight.

Fly's like a champ.

she def gets nose heavy with a newengine on it, i put a evo .46 on mine and it was extremly nose heavy, if I could do all over again I would have just moved the battery behind the servo tray, but instead I took 2oz o lead and stuck them on the bottom of the stab right up against the fuslage then i took two screws and secured them, it flew great till I got a bit cocky with her.........may she rest in pieces. good luck

hi guys, well i got the batt moved to the space behind the servo tray and went and got some great planes sticky lead weights. i'm just wondering where would be the best place to stick them? i know on the tail, but where? top, bottom, or the sides? right next to the fuse, or out on the tail feathers? also do i cut the covering and stick them to the wood or no ? sorry about all the ? thanks for your help

The further rearward the more effective they'll be, so as far back as possible on the fuse. You won't notice them if they're on the fuse, immediately below the horiz. stab. The best place, if you can get in there, would be inside the fuse. I prefer to epoxy them or screw them. If using epoxy, wood is a must. If using a screw and 2 sided tape, the covering may not need to be removed.

Do not put them out on the tail feathers, keep them close to the fuse C/L to prevent latteral balance issues. Also, a plane with it's weight towards it's centerline will roll faster and stop rolling faster. Like a figure skater with her arms pulled in to spin faster.

J

opposite side of the muffler, under the horizontal stabilizer, as far back as you can get it. Try balancing your plane with a little piece of the weight sitting on the stab just above where you would install it to get an idea of how much weight you need. as said above, the further back the weight is, the more effective it is and the less you need. on my plane I cut a square out of the covering JUST bigger than the piece of weight to expose wood, then epoxied the weight on, coating the weight in epoxy.

ok, you guys keep saying epoxy them. is it better to do that than to use the sticky tape on the back of the weights? maybe less of a chance they would fall off, and throw the balance out while in flight? is this what you guys are thinking or no? and what would be better if so, 6 or 30 minute

Epoxy will hold up better, especially if wet or covered in fuel/oil; it's 'permanent'. 30 min is always better if you have the time to use it.

great, you've been alot of help. thank you