Bob Mitchell

Based on the info on OS's website I started out with a 14X6, and wasn't real pleased. Based on a recommendation from here, I dropped back to a 13X6, and am still not pleased. Speed isn't all that great, and neither is vertical. I'm turning about 12K at WOT.

What difference would I see with the 15X4?

Thanks,

w8ye

My Feedback: (16)

The 15 X 4 should give good vertical and the speed wouldn't be good at all

If you like speed the 13 X 6 should have been pretty good for you?

A 12-7 or 8 might do something for you if you like speed?

I don't have any actual experience with the Os 75ax. My experience is with the Super Tiger and Tower 75's

wjcalhoun

Bob:
I used the OS website also to select my initial 13x6 and 14x6 props; i'm not complaining about the 14x6 performance. It just that I thought a 75 sized engine on a 60 sized plane would have given very strong vertical

armmentdog

I just finished building a 4 Star 60 kit. I installed a Saito 100 on it and the plane flew great. For quite some time now I've wanted to go gas. The Zenoah G20 was slightly too big to fit on the front of the plane. Once I heard of the Saito FG-20, I ordered it. Has anyone tried this combo on the Four Star yet? Time permitting I'm going to try installing the gas engine this weekend.

w8ye

My Feedback: (16)

A friend put a Homlite 25 on one. He cut the fuselage back 2". The plane flew fair but it ruined all the well known aspects of the plane. It made the plane too heavy.

armmentdog

The FG-20 only weighs 9 oz (including ignition and muffler) more than the FA-100. CG shouldn't be a factor as I mounted the rudder servo in the tail, and will move the battery aft. I'm powering both the receiver and ignition with one battery (2600mah). Given that the 4* has a very light wing loading, I hope 9 oz. won't effect the flight characteristics too bad. Good weather providing, I'll have a report this weekend.

wjcalhoun

I'll be interested in hearing about the FG-20 performance. I agree - the wing loading on the 4* is so low that if CG is appropriate, the plane ought to handle a few extra ounces from the gasser. What prop are you flying with it?

armmentdog

Currently I've got a 16-6 on the FG-20. I'll have RPM and thrust figures this weekend. Right now I'm out of town on a work related trip.

armmentdog

I misspoke when I said that I had a 16x6 prop on my FG-20. Instead I have a 16x8. This prop seems to be a bit much for the FG-20, well at least it is running 20:1 Gas/Oil mixture. With this prop the engine idles at 2700 rpm and tops out at 7300 rpm. My next step is to try a 16x6 prop or maybe even a 15x7 3 blade.

It took a little while to get the FG-20 tuned. Now that I have it dialed in, it seems like a good purchase. Hopefully I'll have time to put it in my Four Star 60 in the very near future!

wjcalhoun

Thanks
Let us know how the other props turn up. Are you getting thrust measurements with the RPMs?

armmentdog

No, I don't have any thrust measurements yet. My engine test, break in stand, is pretty rudimentary.

yearnin to Fly

My Feedback: (52)

Does anyone know the center of gravity or cg on the fourstar 60? Thanks

w8ye

My Feedback: (16)

The trailing edge of the main spar

Pit-Viper 1

My Feedback: (12)

Yeah its basically anywhere on the main wing spar. Rear most is where I prefer to set mine as well.

laptopguy888

Thanks To all. I am testinga 15cc engine I bought, it is broke in enough to fly it, But still needs ALOT more breaking in.

Pit-Viper 1

My Feedback: (12)

If it's gas don't waste a lot of time breaking in on the ground, tune it and go fly. Over rich setting don't do them any good either like nitro. Keep rpms low to mid with an occasional full throttle for a few seconds and you should be good after a gallon or so.

Can you get any video, love to see the four star in action.


Shane

w8ye

My Feedback: (16)

15cc and a gallon of gas - gonna be a few hours flying

Pit-Viper 1

My Feedback: (12)

Yep lol took many trips to the field for me too achieve this as well.

Shane