Robotech

My Feedback: (9)

I posted this in the Glow Engine forum and didn't get any responses so I'll try here. I have an older original H9 100" Cub that I used to run a Saito 150 in. With the 150 it had almost too much power ( if that's possible ). I had semi-retired the Cub and installed the Saito 150 in my Goldberg Monster Pitts which is a nice combo. Now I have decided to put the Cub back in the air and have a question. I have an OS 120S-E NIB. Will this be enough engine to handle the big Cub? It will be flown scale.

Robotech

My Feedback: (9)

No responses here either. Hmmmm. Guess I'll do it the old way. Stick that sucker on there and hope for the best.[sm=frown.gif]

Bob Laine

My Feedback: (91)

The OS 120 should provide all the power you need for the Hanger9 Cub. It will probably fly in a scale like manner. Bob

Yellowflier

I'm flying the H9 100" Supercub with the Saito 150 and I don't think it really needs this much power. To fly scale I don't need more than half throttle at any given time and 1/3 throttle is actually fine for most general flying. I don't know if a real Supercub can knife edge but mine will at about 2/3 throttle and I can fly it through a loop at half throttle with an 18x6 prop. Stall turns and wing overs are at half throttle as well. I don't know , it's a nice combo but I tell yah if you uncork that 150 the cub litterally flies like a pattern plane !!! I'm always pulling back on the throttle.

Ultimately, down the road, I have a home for the 150 ( have to finish my Midwest AT-6) and I'm thinking seriously about installing the new Saito 125 in the Supercub. It should be plenty powerful enough and be better on fuel as well. I think the top prop it will take is a 17x6 and that would be fine on the Supercub if the engine really pulls that prop well. I'd have to relocate the battery pack forward under the fuel tank or in to the cowl area I suppose, as the 125 is quite a lot lighter than the 150.

I've had a problem with the 150 and fuel delivery, the stock position for the tank I feel is too high ( first half of the tank is too rich then when the tank gets low the engine quits after touch down) and to lower the tank to the under side of the shelf supplied creates it's own trouble with the tank actually too low. Between breaking in the engine and tank position I've had some fun with quitting, stalling, too rich, too lean, sometimes maybe just right then it stumbles again). I'm thinking about cutting that shelf out and getting the tank more closely centered to the carb spray bar, FWIW. Right now it's running rich but good with no pressure tap and the tank lowered. I imagine it would be the same for the 125, plus I'd be starting all over again with a new engine to break in.

I think your Cub would fly fine on a 120, you wouldn't have as much reserve power obviously and you would need to keep it on the wing more than now. It should climb out fine at maybe less than a 45 deg angle, as the 150 can do at half throttle ( I climb out sharp and level off at maybe 20 ft. off the deck at half throttle all the time) !! You would have more throttle throw, that is to say you might hit it wide open now and then. I'm not sure what prop would be correct and I'm not familiar with your particular OS engine but it will fly.

David

Robotech

My Feedback: (9)

I finished up mounting the O.S. yesterday and took it out to the field. I moved the battery pack up front under the tank against the firewall and used a weighted hub and it balanced perfectly at 4.75".

Fired up the engine for break-in and it idles ( MUCH better idle than the Saito ) and transistioned perfectly. After a couple of break-in tanks I fueled it back up and taxied out. Beautiful power ( scale ) and it had plenty in reserve. Mind you not like the Saito 150 had but plenty none the less. It pulls it through a big loop just fine. I'm using a wooden 15X8 Zinger prop and 15% Cool Power.

Overall I am VERY impressed with the performance of the O.S. and it's allot easier on fuel.

Side note: I have the Saito 150 in a CG Pitts now and I fought that engine in the 97 deg. heat for an hour Saturday before I finally gave up on it. I may be a O.S. 4-stroke convert now.

Yellowflier

Sounds like it's going to work well for you !!

I changed my Saito 150 prop on the H9 100" cub from the Master Airscrew Classic 18x6 to a Dynathrust 18-6 and retuned with the pressure tap hooked back up running on CoolPower 10%. It flew a few flight ok and used less fuel than it ever has, but then the low end started flooding out on long approaches so I had to retune the low end. That picked up a bunch of low end RPM and I retrimmed for 2300-2400 RPM idle speed. Flew it last night , it seemed fine and sipped fuel compared to before. I'm going to fly it today and get a better grip on this combo. I think if I want a much lower idle I'm going to have to go inside and move the rod a bit as I'm closing in on full trim at the box.

Don't give up on your Saito just yet in a general way though. I know you are all set now on the H9 Cub with the OS 120, but for other palnes I can tell you first hand that 150 has an unbelievably long break in period and you really do need to readajust the valves after an hour or two of running time on break in. You can't even think about leaning it out for peak running till a few gallons of fuel has gone through it, you want a good 400- 500 RPM drop on the high end and just rich on the low end for break in reliability and it will suck fuel set up this way. I'm at 4+1/2 gals now and it's coming in but several folks have told me wait to ten gals before you expect too much from it.


David