Hello,

I have a very tailheavy Kangke Extra 300s 60 size.
I am using a Saito 100, the weight is about 7 lbs before
adding a chunk of lead about the size of my thumb strapped to
the engine mount.

What can I do apart from having this piece of lead strapped on?
I am already using pullpull on the rudder.

L

If you have the room inside the fuse, you could move all the radio gear foward as much as possible. Other than that, the only choice is adding weight to the front to balance it, short of major surgery on the tail feathers.

Vince

If all of the radio gear is mounted as far forward as possible, then there's really not too much more you CAN do but add weight at the mount.

I agree with the other posts but I have another suggestion I had the same problem with my flybaby with adding weight I had originaly put about 1&1/2 lbs of lead in a compartment just behind the firewall and on the engine mount this much weight did not make me to happy so I had to figure a better way so what i did was put the weightas far forward as possible so i glassed the lead inside the nose of the cowl and put a heavy hub on the engine and reinforced the cowl mount with glass and added 2 more mounting screws and with moving the weight forward i used about 10ozs of weight so that saved alot.

Here's a little bit better Idea move the engine fowards on the mount. If you cant do that shim the engin forwards with a shimm behing the engine mount then relocate the cowl. This way you don't have to add so much weight to the plane . :idea:

I am inclined to agree with nchrome. A model that far out of balance IMHO has a basic design flaw. Best you can do is take as much weight out of the tail as possible, cram battery & servos forward, maybe substitute a heavier engine, then explore moving the engine forward a half inch or whatever it takes. You should be able to get someone to help you with the math if necessary to calculate how far forward to go. Basically a question of calculating moments. With a toy balsa glider you just move the wing back. There are no fixes for such a drastic problem that don't either take a lot of work or look a little strange. Sometimes the best fix is start a new model. The fun part of this hobby is flying, not rehabilitating hopeless cases. I used to say in my fishing days, I enjoy a challenge, but before I go home I want a good fish!

I did the engine mount move and the servos also using sub c cell pack im only running a 91 fs on it so it is a minumal engine but pulls it scale like as far as cg on this kit it was not where it shows on the plans it had to be moved almost a full inch forward when i balanced it to the plans it flew very tailheavy and almost lost it lucky the landing only resulted in minor damage and nylon bolts sheared off the way they should .I wrote Dynaflite a letter about how they should modify the plans but no response.but she flies beatiful now .I was just offering another option to balance out his aircraft also if you put weight in the cowl try to keep it low as weight on top will posibly cause snaprolls.

You should contact Kangke. The tech support from them is very good.

Yes, I contacted them and the guy indicated that the CG in the book was a bit conservative and most likely it could be moved back later on.

I put in a 5 cell battery up front and it seems more manageable now.

I remember my dad using a lead weight once that can fit into the spinner. This put it as far forward as possible. Is this considered unsafe to put extra weight here? I guess I could see the excess weight acting as a gyro or putting excess stress on the engine.

Thanks,

Herb

Herb,
Your dad must have it balanced pretty well. I could see something like that shaking a plane to pieces. Too funny!

Now see what you've done - you've got me into a laughing fit

Russ.

It seemed to work pretty well. I should have clarified and said that it was made to be mounted on the crankshaft just beyond the propeller. It wasn't just shoved into the spinner. I'm guessing it could easily be balanced as a unit with the propeller. However, since all the weight was centered around the axis of revolution, it would be difficult to get this thing out of balance unless it was made poorly.

I think the plane flew horribly, though. It didn't have anything to do with the engine or vibration.

Maybe weight in the nose would still "shake the plane to pieces." That's why I'm asking. Just curious to know if anyone else has tried it. I figured someone would have since so many are worried with weight.

Herb

Herb,
I wasn't trying to be insulting. That just struck me as genuinely funny. It makes sense to try to put the weight as far forward as possible. But putting it on the propeller shaft so that it spins with the propeller (even if balanced) would cause it to act like the flywheel in your car. In a car, the flywheel is there to help the engine run smoothly, but it also causes the engine to rev up, and slow down more slowly. When I was younger, I had a souped up '56 bug with a lightened flywheel in it. It was noticably peppier and quicker off the line.

Russ.

I know you weren't being insulting. I probably would have thought it was funny too if I hadn't seen it before. I can see a number of reasons why someone wouldn't want to put weight there, I was just didn't know if my reasons were validated.

Herb

I once used a weight like Herb mentioned and flew a couple hundred flights on the plane in a couple of seasons without any problems. The weight was fairly precisely fitted to the propshaft and keyed so the prop actually interlocked with the weight.

Later on I read in RCM that it was dangerous so I took the weight off, but my experience was that it worked for me. Maybe there was more than one manufacturer out there and I got the good one.

Your mileage may vary.

I know that this might seem a little bit beginer like advice but have you checked the Incodence of both the top and the bottom wing,and also the thrust line of the engine. Cause some of the syptoms you have described could be the incodence being off. After you take off try (at a safe altitude) a hight speed pass and throttle down the engine and see what the plane might do. Course the othere you can only tell with an incodence meter. :thumbup:

Hello,

it appears that I was somewhat inaccurate in my prebalancing checks.

I have now used a 5 cell nimh receiver pack up forward and I gave the inside of the cowl a thin coat of epoxy to beef it a little and with the spinner the plane is almost at the cg indicated in the book.
i will just tie on a small piece of lead to the front and if I need to remove nose weight later on I will move the battery back.

The plane is just over 7lbs powered by Saito 100.
hoping to fly this Sunday.

L