Mountain Man

I'm scratch building a 1/4 scale Ryson Cloudster ST-100 motor-glider. !4.4 ' Span; 13.5 sq.ft. Area; Aspect Ratio = 15.5; HQ2513 root blended to HQ3015 at tip; all moment arms fall within ideal limits for sailplanes; both horizontal and vertical tail volume coefficients are within ideal limits. Firewall to prop distance is about 8.25" long and 8" wide inside the cheeks. Nose moment arm is 16.75" (1.52 x MAC).

Estimated weight of completed airframe, landing gear and entire radio system including linkages is 10.5 lbs. (168 oz.).
Without the power plant and fuel the estimated wing loading is about 12.5 lbs./sq.ft.

I want to be able to shut down and restart in the air, as would a full-scale ship,so part of the power plant, if I use an internal combustion engine, would be a starter and its battery.

I also want to be able to sustain a 30 to 40 degree climb angle up to about 600 ft. AGL and repeat climbs at least five times.

Electric power is an acceptable alternative for me.

How about a supercharged YS91 with a Hobby Lobby HLFE12 in-flight starter with a 14/10 prop?

How about a Hacker 50-11L with 5.2:1 gear reduction on 20 NiMH cells with a 20x11 prop?

I live and fly at 4700 ft. ASL in Montana. Air varies from cool and dry to colder than hell and dry! The alpine soaring is phenomenal and there is so little traffic I can take off and land on the state highway. I would use county roads but the're too rough. The Interstate works but I have to climb fences and a cars come by too often, about one every 20 minutes. Town is 75 miles away and both people there only recognizes RC as a soda pop.

Someone please talk to me!

Ollie

I would go with the YS91 and on board starter if it will fit. It will give you the best power to weight ratio. With no other people around, noise won't be a problem. Wear ear protection and leave off the muffler for a bit more power. You might want to put a 120 in if it will fit.

BTW, I calculate your wing loading to be 12.44 ounces per square foot, not pounds per square foot. With engine and fuel it will be upwards of one pound per square foot. I estimate your stalling speed at that altitude to be about 25 MPH.

Mountain Man

Ollie,

Thanks for the input. Others have said the same thing. They also said that the supercharged YS 91 has almost as much poop as the YS 120. (the supercharged 120 is currently not available) . Any input on other starting systems?

Thanks again,

J. J.