I have a low wing 40 size plane that has 56in wing span and the plane weigh in at 5lbs and 8 oz that with everything but the engine and the receiver.Is a 46 ball bearing engine big enough to get good performance out of the plane

Yes a typical .46 is plenty for that size and type of Sport aerobatics aircraft. Truth be know for many of that type a .40 is plenty for a 40 size aircraft Hmmm what a concept.

If you want to get silly sure throw a .55AX in it, those types of airplanes can be fun to. Heck the other end of the spectrum can be educational also. I recently have be flying and training folks with an eighty inch Senior Kaydet that most folks use a sixty or bigger two stroke and I am using a .35AX.

What a surprise that is turning out to be and certainly not stiffled in the aerobatic department either, Everyone is wanting to fly that thing.

So yes a 46 will be fine and its your choice.

John

I guess it partly depends on your definition of good performance.
That is typical size and weight for a 40 size sport plane. If it is a sport plane a 46 should be plenty. If it is a 3D model you probably need something bigger.

Depends on what you want it to do. If you are looking for a simple sport flying then yeah a .46 would work. Best thing to do is look at the maufacturer's specs and start there. The OS 55AX is my favorite small engine in this size range. OS also offers the 65, 75, and 95AX sizes as well.

A plane that size with a good running .46 will be an outstanding performer.

I don't recall the weights of the small planes I have had but that sounds about right. I used a lot of .46 la engines in them and that was plenty of power for sport flying. I have never been a big fan of the .40 engine but like John said, that's why they are called 40 size planes.

5lb 12oz w/o engine & Rx sounds heavy. I have two SuperStar 40's that weigh 5lb 12oz ready to fly dry. My HobbiStar 60 is 7lb 14oz RTF dry.

One of the SuperStar's has a 46AX and flys GREAT. But your plane with a 46AX and Rx would come in at 6lb 9.5oz dry and w/ a 55AX 6lb 12oz, a lb heaver than my 40 size trainer. I would at least look at 55AX 1st, but the 46AX would fly it just fine to.

Its a fallacy that the 40 sizers need a 46 or 55ax. A colleague at the field is flying a 40 size 60" span trainer with a 35 size 2c and it can do all the aerobatics that a trainer can do and more. You just need to prepare a bit earlier (give throttle earlier) so you have airspeed to finish the move. Limited to just sports flying of course. If you want 3D, some will say even a 75 will not be enough (airplane being suitable ofcourse)

Ameyam

Read Johns post about his SK and the .35. I have seen several of these planes with a .46 and the .46 had gobs of extra power. I once flew a glassed and painted 40 size Supersportster with a .46la, it flew the plane but there was no OS factor at all in it. That was a very heavy plane I bought at auction. There is still a big difference between flying the plane and getting it off the ground. If I have to dive a plane to do a tight loop then it is under powered. The OP is looking for good performance. That is an opened term but a good .46 should do it in most cases. I look at good performance as being able to pull a plane from straight and level flight at half throttle and being able to roll power on as needed to perform a giant sky filling loop. I'm talking a big loop, not a tight little over the top loop after a dive.
This brings up the question for other pilots. How do you look at enough performance. I fly a very nice basic known pattern sequence with a 2 meter patterrn plane with a YS 1.20 engine. The plane should be running a bigger engine due to it's weight but it does everything I want and is really smooth. I feel it has very good performance.

For thr OP's airplane 46 is good enough is what I wanted to say. Think we are on the same page, just reading different lines. You dont have to dive a plane to do a loop if you are using a lower size engine, just add power a bit earlier so you have the airspeed at the start to finish the loop. Also, you cant do loop after loop (atleast I couldnt, but may be with more throttle management...) thats all

Ameyam

.46 will be fine. But don't let someone talk you out of overpowering a model. It's the most fun you can have. Personally, i'd throw a 55ax on that puppy and be done. I think you'll find that the 55ax will be a better long term investment too when you eventually want to try 3D flying.

well one of the guys at my club gave me a HB40 engine that is the engine that was on it when i seen it fly so i'm going with it if the weather is nice tuesday i'll take it up . let y'all know how it dose.

That engine will do just fine

John

Well I didn't to fly the plane tell Saturday Like i said i put the HB40 on it and that is what this plane needed it flew beautiful I didn't tell you what plane it was so here it is it's a 1970ALLEYCAT this is a beautiful plane and i just fell in love with it the first time i seen it .At half throttle you can loop it spin it and do just about anything you can think of. That HB40 has about the same power that a OS 60 has.

46 size engine would rock, Thunder Tiger, Magnum or ASP with 11X5 to 11X6 prop

Good Luck

Congratulations and enjoy

John

I had a Southernb RC Alley Cat in 1978-1979 and loved it. Had an OS 45 FSR in it. and it is a great flying airplane.

Bruce