I just finished a somethin Extra kit build. The tail was very heavy when I balanced the plane. I wanted to see if anyone else had this issue. In the end I had use lead wieght to balance the plane. It weighs 5.4 lbs and I am using an OS 46 LA. Is this engine going to be sufficient for the weight?

Any advise would be helpful.

I now have a Saito 72 on mine. When I had a ST 51 on it. I had the engine pushed way out on the mount to get the CG right. Even the 72 is out pretty far on the rails.

David

Thanks David.

Do you think the 46 will pull the wait?

Good luck with the "Something Extra". It is a great plane! I originally came out tail heavy. The first engine I mounted was a Magnum XLS.46. It was ok, but it didn't give me the verticals that I wanted. I switched it out to a Magnum Xl.53 with an APC 11 x 5 prop. I also tried to lighten up the tail. I ditched the support wires on the tail and I also moved the engine as far forward as I could on an engine mount. I have an OS .46LA I have tried to use it on several planes, I usually end up taking it off and mounting an engine with some guts. They are a good engine, just kind of so so on the power. I may make another "the Hots" and try the LA on that. it's total fly weight is only 3.5LBS.

It may be a good deal for you. Good luck with it.

Frank

Mine has a ST .51 with a MACS muffler and a Tru Turn Spiner and it was still tailheavy. I got a 6volt NiMh battery, It is a little heavier and pushed it as far forward as I could. I had it in the space under the fuel tank and that was a little too far forward, I ended up with it mounted vertical against the bulkhead between the fueltank and forward of the aluminum wing tube. it fits snug and velcroed it in and it balanced perfect. The 6 volt battery speeds up the servos and gives a little more torque and that makes the extra weight useful instead of dead weight like lead. About the OS LA series, I have heard stories that they are a weak engine, reliable but gutless, it is a bushing engine and it seems to me there is a lot of internal drag, I have always had, and will try to stick with ball bearing engines, a little heavier but they have more power, and a heavier engine will help with the CG problem

I also have a ST 51 in and I had put an extra 3/4" on the rudder when building plus Sullivan tail wheel; it was a little tail heavy but put the battery under the fuel tank and it balanced fine.

mine flies great with a ST 40 and an 11-5 apc

I fly mine with a GMS.47 . I have built the kit SSE , and mine came out very tailheavy . The ARF with the same engine balanced more closely . The ARF has tail feathers made up of stick balsa, where as the kit has stamped out balsa , I think this is why the tail is heavier on with the kits.

Rick, a 46LA will fly it fine for sport flying. I think you know you are on the lower end of the power scale with the LA. If you get where you want to hover and really pull it around, think about a good 4C or a OS50-55. The throttle linkage is a pain if you go 4C on this plane, but it can be done.

David

Rick
I too am just finishing the SSE and have found the same problem. I have a Saito 65 mounted with servos at the tail to balance the heavy Saito. I checked the balance before I mounted the servos which seemed to work fine but now covered it is far off. I took the tail braces off, attached a metal prop nut under the spinner, and pushed the 1500 mAh battery all the way forward over the tank. This balanced it fine but now I'm adding weight with the prop nut and whatever else has to go up front. I had my wife set the braces on the tail as I held the plane at CG and immediately it took a tail dive. Think I'll use the braces for show but fishing line for go.[sm=72_72.gif] Anyone out there have any ideas?
Steve

Mine has the .46 ax and I had to put my 1800mah 4.8v flat pack as far foward as it would go, but still right under the cockpit. It still balanced just slightly tail heavy, but this is the way I like it to fly. The .46ax runs great but barely has enough power to hover with a 12.25 X 3.75 prop. While it would probably be fine for relaxed sport flying, I don't think I would like this plane with a .46 La. The .55ax would probably be my first choice for this plane if staying with a two stroke.

OK. I spoke too soon. I had it balanced nice "on the table" but maidened this weekend and had the following observations:

1. Level flight when trimmed and at medium throttle. However, at full throttle, it REALLY wanted to climb at a high rate.
2. When landing on still air conditions, floated in nice. With 10-15 mph head wind, it really wanted to stay nose up and not come down.
3. When flying inverted, it took a lot more down elevator than I thought a mid-wing (no di-hedral and symetric foil) would take.

Suggestions at the field were:

* CG too tail heavy (Observation #1 and 2)
or
* Thrust line for engine is too high; add some washers to top to lower thrust line (Observation #1 and 3)

Suggestions based on above observations?

If it is balanced tail heavy, shouldn't inverted also climb?

I flew my SSE this weekend. Really likes the plane but the .46 LA is not powerful enough. I needed almost the whole runway to take off. Once I was in the air it was fine for my skill level now but won't be for to much longer as I fet used to the plane.

Can't give you the areodynamic explanation why, but mine is definitely tail heavy and still requires some elevator when inverted. But I would guess this is probably caused more by wing incidence or thrust angle than balance.

Hugger, where, relative to the main spar, is your CG (such that you say it is tail heavy? Mine balances right out to the plans and hence I am not convinced that is my issue.

l'll have to check the manual again to be sure but my memory says the Cg is supposed to be 3 1/2" from the leading edge of the wing and mine is set almost 3 3/4". I would agree your problem may not be a balance issue. But I doubt that the recommended Cg is designed to give a true "neutral" balance. Most likely it is designed to be just slightly foward of "neutral" for stability. Even though mine is set near the recommended limit of range for the Cg, it still requires a little elevator when inverted at less than 3/4 throttle or so.

Recommended CG is 3 1/2" back. Or better yet, at the main spar.

Rick,

What size prop were you using? I think the engine runs at it's best with an 11x5 or 11x6.
It's too bad, this engine is just so weak. When I bought mine I was a newbie and I got suckered in to buying this engine because everyone at the field had only good things to say about OS engines. And, it is a good engine just not as powerful as you would expect a .46 to be. I think it runs like a weak .40 myself. I still haven't gotten any real use out of it. 4 years later it is sitting on a shelf.
I mounted a Magnum XL.53 with an APC 11x5 prop on my SSE. This gives very good performance on this plane. I have plenty of vertical and speed.

Good luck
Frank

Frank,

I was using an 11x7 and just swithched to 11x6. I hoping it will be better.