I am thinking about putting an OS120 4 stroke (with pump) on a sport plane. Is SIG's four star 120 a good choice? If four star 120 is not a good choice, can somebody recommend a good sport plan for this engine?

Thanks in advance.

onewing:

It will work fine, but the 120 plane is usually meaning a two stroke 120, with the 4s you might be happier gettin a plane for a 2 stroke around 0.80 size, being more the equivalent of the 120 4s engine.

Bill.

Bill,

I agree with you. I have a hard time finding a good sport plane that I can use my OS 120 four stroke. Any suggestions?

I usually use these 120 size four stroke engines for my 60 size warbirds (Top Flight). I have a TF P40 ready for covering and it has a Saito 120 in it. Building and flying these warbirds is exciting. But I also need a sport airplane that I can fly every weekend without worrying about how much time and money that I have invested in it.

Thanks.

Onewing

I think that if you do a little research you will find that the 4* 120 was designed for a 4 stroke 120 size engine. I have one on mine and it has plenty of power.

Re-Kit

onewing:

If you don't mind a "Stick" plane, the "Joss" stick from Hobby people is nice, the Ultra Stick 60 would work well.

If you don't mind building there is the "Killer Stick" from Northeast Aerodynamics.

Engine Requirement: .61 to 1.08
Wing Span: 81”
Wing Area: 1303 sq. in..
Fuselage Length: 69.5"+ Engine
Weight Range: 8.0 lbs
Radio Functions: 4-8 channels

http://www.ne-aero.com/killerstick.html

Highly recommended, big, but light. Size of the UltraStick 120, but the weight of the US 60. Your 120 should hover it with no problem, and accellerate vertically from the hover.

Not the cheapest, $149.95 plus $15 S&H to your door, also far from the most expensive. And it's far nicer than any ARF.

Bill.

Re-Kit:

Thank you for telling me that 4*120 was originally designed for a 4s 120. You made me more comfortable about going this route.

Bill:

Thank you for the quick response on recommending sport airplanes. I already have a H9 Ultra Stick 40 and like it very much. However, I think one stick is enough for me. I do like Northeast Aerodynamic's kit. I had their Sport Air 40 and was really impressed with the quality of that airplane. At this time, I am looking for a sport kit to build.

Thanks.

Onewing

I installed a RCS 140 gas with 2 servos in the tail the plane balances out great weight is 12pounds and flys great, good vertical but not unlimited, and best of all sips gas and no glow fuel goo to clean.

Which one has more power/torque - RCS140 or OS120 with pump?

Thanks.

Onewing

I just finished a 4*120 with a pumped OS 120. It flys great! Does every thing I could want. The only problem I have with the plane is the size of the wing. Boy that sucker is long. I have to load it over the front seat of my Explorer and have it stickup in to the back. But I still love IT!

I'm in the finishing stages of my 4*120. It will be powered by an OS 160. I made many modifications to the kit. I totally rebuilt the wing to make it stiffer by sheeting the leading edge and adding cap strips. The wings were also clipped by one bay on each end and rounded wing tips were added. The tail feathers were stream-lined by rounding the squared off corners and all control surfaces were tapered. I also cowled in the nose to the shape of a 3" spinner along with adding wheel pants. Overall weight, 11 lbs. Just hope she flies as good as she looks. I Plan to find out in about a week..........RS

Redbear,

Great to know that you are successful with the OS120. I think I will just go ahead with this combination. 4*120 + OS120.

Russmall,

Can you post some pictures?

Thanks.

Onewing

Mine will be powered with a MVVS 160 gas engine. I just posted on it in the Giant forum:

http://www.rcuniverse.com/showthread...515&forumid=38

The wing fits on the back floor of my Suburban just fine . I still need to paint the checkerboard on the other half..

The fuselage with engine test fitted.

Would you let us know how the balance works out? That gasser would make a nice plane out of it.

I got it finished and flew it today. I put the servos in the tail and it came out tail heavy. So far I've added 5oz of lead to the nose and it still balances about 1" behind the back of the CG range.

I could tell flying it that it was tail heavy too. It was very pitch sensitive and not at all comfortable to fly like that. I'm gonna have to shift some things around a bit to get the CG correct. I hate adding dead weight for balance. Because of the gasser engine I'm leery of shifting the R/C gear forward due to the possibility of interference from the ignition. Will try it again tomorrow with a few changes.